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Fatigue reliability of wind turbine components.
National Technical Information Service (NTIS)
Fatigue life estimates for wind turbine components can be extremely variable due to both inherently random and uncertain parameters. A structural reliability analysis is used to qualify the probability that the fatigue life will fall short of a selected t...
P. S. Veers
A stochastic DEVS wind turbine component model for wind farm simulation
Microsoft Academic Search
Wind farms use several wind turbines to generate electricity and provide a renewable source of energy. However, due to large forces as a result of hourly and seasonal variations in wind speed and direction, wind turbines experience stochastic loading that often lead to failures of wind turbine components such as the gearbox and generator. Wind turbine failures result in costly
Eduardo Pķrez; Lewis Ntaimo; Eunshin Byon; Yu Ding
Fatigue reliability of wind turbine components
NASA Astrophysics Data System (ADS)
Fatigue life estimates for wind turbine components can be extremely variable due to both inherently random and uncertain parameters. A structural reliability analysis is used to qualify the probability that the fatigue life will fall short of a selected target. Reliability analysis also produces measures of the relative importance of the various sources of uncertainty and the sensitivity of the reliability to each input parameter. The process of obtaining reliability estimates is briefly outlined. An example fatigue reliability calculation for a blade joint is formulated; reliability estimates, importance factors, and sensitivities are produced. Guidance in selecting distribution functions for the random variables used to model the random and uncertain parameters is also provided.
Veers, P. S.
Wind Turbine
USGS Multimedia Gallery
The species of bats that are most susceptible to wind turbines all roost in trees throughout the year, leading some scientists to speculate that they may be visually mistaking wind turbines for trees in which to roost....
75 FR 2159 - In the Matter of Certain Variable Speed Wind Turbines and Components Thereof; Termination of...
Federal Register 2010, 2011, 2012, 2013
...337-TA-641] In the Matter of Certain Variable Speed Wind Turbines and Components Thereof; Termination of Investigation...United States after importation of certain variable speed wind turbines and components thereof that infringe claims...
Multi-component wind measurements of wind turbine wakes performed with three LiDARs
Field measurements of the wake flow produced from the interaction between atmospheric boundary layer and a wind turbine are performed with three wind LiDARs. The tested wind turbine is a 2 MW Enercon E-70 located in Collonges, Switzerland. First, accuracy of mean values and frequency resolution of the wind measurements are surveyed as a function of the number of laser rays emitted for each measurement. Indeed, measurements performed with one single ray allow maximizing sampling frequency, thus characterizing wake turbulence. On the other hand, if the number of emitted rays is increased accuracy of mean wind is increased due to the longer sampling period. Subsequently, two-dimensional measurements with a single LiDAR are carried out over vertical sections of the wind turbine wake and mean wake flow is obtained by averaging 2D measurements consecutively performed. The high spatial resolution of the used LiDAR allows characterizing in details velocity defect present in the central part of the wake and its downstream recovery. Single LiDAR measurements are also performed by staring the laser beam at fixed directions for a sampling period of about ten minutes and maximizing the sampling frequency in order to characterize wake turbulence. From these tests wind fluctuation peaks are detected in the wind turbine wake at blade top-tip height for different downstream locations. The magnitude of these turbulence peaks is generally reduced by moving downstream. This increased turbulence level at blade top-tip height observed for a real wind turbine has been already detected from previous wind tunnel tests and Large Eddy simulations, thus confirming the presence of a source of dangerous fatigue loads for following wind turbines within a wind farm. Furthermore, the proper characterization of wind fluctuations through LiDAR measurements is proved by the detection of the inertial subrange from spectral analysis of these velocity signals. Finally, simultaneous measurements with two LiDARs are performed over the mean vertical symmetry plane of the wind turbine wake, while a third LiDAR measures the incoming wind over a vertical plane parallel to the mean wind direction and lying outside of the wake. One LiDAR is placed in proximity of the wind turbine location and measures pointing downstream, whereas a second LiDAR is located along the mean wind direction at a downstream distance of 6.5 diameters and measures pointing upstream. For these measurements axial and vertical velocity components are retrieved only for measurement points where the two laser beams result to be roughly orthogonal. Statistics of the two velocity components show in the near wake at hub height strong flow fluctuations with magnitudes about 30% of the mean value, and a gradual reduction for downstream distances larger than three rotor diameters.
Iungo, G. V.; Wu, Y.-T.; Portķ-Agel, F.
Wind turbine apparatus
US Patent & Trademark Office Database
A wind turbine apparatus including a shaft, two wind turbines, and a two-piece alternator. The turbines and the alternator are mounted on the shaft. The alternator is located between the turbines. The alternator includes a circular permanent magnet component fixed to the first turbine, and a circular electrical winding component fixed to the second turbine so that, when an effective wind blows in a direction perpendicular to the longitudinal axis of the shaft, the first turbine and the circular magnet component will rotate around the shaft in a first direction and the second turbine and the circular winding component will rotate around the shaft in a second direction opposite the first direction, thereby generating electrical energy.
225-kW Dynamometer for Testing Small Wind Turbine Components: Preprint
SciTech Connect
This paper describes NREL's new 225-kW dynamometer facility that is suitable for testing a variety of components and subsystems for small wind turbines and discusses opportunities for industry partnerships with NREL for use of the facility.
Green, J.
Wind turbine
A wind turbine to convert wind energy into hydraulic energy by a positive displacement hydraulic pump driven by a wind mill. To the oil outlet of the hydraulic pump, a thermo-sensitive control element is attached, which functions when the oil temperature exceeds a certain limit. By the control element, the oil outlet is closed, suppressed, or opened to ensure safety
A wind turbine of the type having an airfoil blade (15) mounted on a flexible beam (20) and a pitch governor (55) which selectively, torsionally twists the flexible beam in response to wind turbine speed thereby setting blade pitch, is provided with a limiter (85) which restricts unwanted pitch change at operating speeds due to torsional creep of the flexible beam. The limiter allows twisting of the beam by the governor under excessive wind velocity conditions to orient the blades in stall pitch positions, thereby preventing overspeed operation of the turbine. In the preferred embodiment, the pitch governor comprises a pendulum (65,70) which responds to changing rotor speed by pivotal movement, the limiter comprising a resilient member (90) which engages an end of the pendulum to restrict further movement thereof, and in turn restrict beam creep and unwanted blade pitch misadjustment.
Cheney, Jr., Marvin C. (Glastonbury, CT)
The improvement in a wind turbine comprises providing a tower with a freely liftable mount and adapting a nacelle which is fitted with a propeller windwheel consisting of a plurality of rotor blades and provided therein with means for conversion of wind energy to be shifted onto said mount attached to the tower. In case of a violent wind storm, the nacelle can be lowered down to the ground to protect the rotor blades from breakage due to the force of the wind. Required maintenance and inspection of the nacelle and replacement of rotor blades can be safely carried out on the ground.
Abe, M.
An improved wind turbine is described in which the tip portions of the blades are variable in pitch and are cyclically varied in pitch to control the yaw of the rotor and to relieve bending moments on the blades and are collectively varied in pitch to relieve bending moments on the blades and to maximize the power output of the
R. E. Donham; R. L. Heimbold
Turbulence descriptors for scaling fatigue loading spectra of wind turbine structural components.
The challenge for the designer in developing a new wind turbine is to incorporate sufficient strength in its components to safely achieve a 20- or 30-year service life. To accomplish this, the designer must understand the load and stress distributions (in...
N. D. Kelley
LIFE Computer Code: Fatigue Life Prediction for Vertical Axis Wind Turbine Components.
The LIFE computer code was originally written by Veers to analyze the fatigue life of a vertical axis wind turbine (VAWT) blade. The basic assumptions built into this analysis tool are: the fatigue life of a blade component is independent of the mean stre...
H. J. Sutherland T. D. Ashwill N. Slack
The effects of variable speed and drive train component efficiencies on wind turbine energy capture
A wind turbine rotor achieves optimal aerodynamic efficiency at a single tip-speed ratio (TSR). To maintain that optimal TSR and maximize energy capture in the stochastic wind environment, it is necessary to employ variable-speed operation. Conventional constant-speed wind turbines have, in the past, been converted into variable-speed turbines by attaching power electronics to the conventional induction generator and gearbox drive train. Such turbines have shown marginal, if any, improvement in energy capture over their constant-speed counterparts. These discrepancies have been shown to be the result of drive train components that are not optimized for variable-speed operation. Traditional drive trains and power electronic converters are designed to achieve maximum efficiency at full load and speed. However, the main energy producing winds operate the turbine at light load for long periods of time. Because of this, significant losses to efficiency occur. This investigation employs a quasi-static model to demonstrate the dramatic effect that component efficiency curves can have on overall annual energy capture.
Fingersh, L.J.; Robinson, M.C.
Wind turbine acoustics
NASA Technical Reports Server (NTRS)
Available information on the physical characteristics of the noise generated by wind turbines is summarized, with example sound pressure time histories, narrow- and broadband frequency spectra, and noise radiation patterns. Reviewed are noise measurement standards, analysis technology, and a method of characterizing wind turbine noise. Prediction methods are given for both low-frequency rotational harmonics and broadband noise components. Also included are atmospheric propagation data showing the effects of distance and refraction by wind shear. Human perception thresholds, based on laboratory and field tests, are given. Building vibration analysis methods are summarized. The bibliography of this report lists technical publications on all aspects of wind turbine acoustics.
Hubbard, Harvey H.; Shepherd, Kevin P.
On the Fatigue Analysis of Wind Turbines
Modern wind turbines are fatigue critical machines that are typically used to produce electricalpower from the wind. Operational experiences with these large rotating machines indicated thattheir components (primarily blades and blade joints) were failing at unexpectedly high rates, whichled the wind turbine community to develop fatigue analysis capabilities for wind turbines. Ourability to analyze the fatigue behavior of wind turbine
Herbert J. Sutherland
A wind turbine assembly including a rotor body is described having mounted thereon a plurality of rotor blades, wherein each of the rotor blades is joined at an inner extremity the blade stem projection extending interiorly into the rotor body and secured there within to the rotor body by torsional- and axial-shock damping connection means, wherein each blade stem projection comprises a hollow cylindrical housing defining a central longitudinal axis therein, with a support member interiorly disposed in the housing at an intermediate position along its axis and fixedly secured to the housing, a shaft fixedly secured at one end thereof to the rotor body and coupled at its other end with the support member in a manner allowing limited axial and rotational movement of the housing relative to the rotor body, and a longitudinally outwardly biasing means between the support member and the rotor body, extending along the axis of the housing and outwardly abuttingly biased against the support member, whereby the biasing means provides torsional and axial shock damping to the rotor blade. The wind turbine assembly includes a nacelle to which the rotor body is coupled for rotation with respect to the nacelle, and a tower having an upper portion to which the nacelle is secured by coupling means, and a lower portion positionable on a support body, the tower upper portion including a cylindrical member at an upper end of the tower, an oarlock connector joined to the bottom stem portion; a pitch biasing and damping member interconnecting the nacelle and the oarlock connector, for pitch damping of the nacelle; and yaw biasing and damping means connecting the oarlock and upper portion of the tower, whereby the pitch damping/biasing member and the yaw biasing and damping means bias the rotor body and nacelle to a selected base position in relation to the tower, and dampen pitch and yaw displacements from said base position.
Lundquist, R.E.
225-kW Dynamometer for Testing Small Wind Turbine Components (Poster)
The National Wind Technology Center at NREL has commissioned a 225-kW dynamometer to facilitate the development of advanced generators, gearboxes, and power electronics to reduce the cost and improve the reliability of small wind turbines.
EEMD-based wind turbine bearing failure detection using the generator stator current homopolar component
Failure detection has always been a demanding task in the electrical machines community; it has become more challenging in wind energy conversion systems because sustainability and viability of wind farms are highly dependent on the reduction of the operational and maintenance costs. Indeed the most efficient way of reducing these costs would be to continuously monitor the condition of these systems. This allows for early detection of the generator health degeneration, facilitating a proactive response, minimizing downtime, and maximizing productivity. This paper provides then an assessment of a failure detection techniques based on the homopolar component of the generator stator current and attempts to highlight the use of the ensemble empirical mode decomposition as a tool for failure detection in wind turbine generators for stationary and non-stationary cases.
Amirat, Yassine; Choqueuse, Vincent; Benbouzid, Mohamed
Floating wind turbine system
A floating wind turbine system with a tower structure that includes at least one stability arm extending therefrom and that is anchored to the sea floor with a rotatable position retention device that facilitates deep water installations. Variable buoyancy for the wind turbine system is provided by buoyancy chambers that are integral to the tower itself as well as the stability arm. Pumps are included for adjusting the buoyancy as an aid in system transport, installation, repair and removal. The wind turbine rotor is located downwind of the tower structure to allow the wind turbine to follow the wind direction without an active yaw drive system. The support tower and stability arm structure is designed to balance tension in the tether with buoyancy, gravity and wind forces in such a way that the top of the support tower leans downwind, providing a large clearance between the support tower and the rotor blade tips. This large clearance facilitates the use of articulated rotor hubs to reduced damaging structural dynamic loads. Major components of the turbine can be assembled at the shore and transported to an offshore installation site.
Viterna, Larry A. (Inventor)
Airship-floated wind turbine
A wind turbine, by use of a tethered airship for support, may be designed for the economical recovery of power at heights of 2,000 feet or more above ground, at which height power density in the wind is typically three times the power density available to a conventionally supported wind turbine. Means can be added to such an airship-floated wind turbine which will permit its generators to be used to meet load demand even during periods of little or no wind. Described to this end is a wind turbine system which combines, among other novel features: a novel tether line system which provides access for men and materials to the supporting airship while in active service, a novel system for providing additional buoyant lift at the nose of the turbine-supporting airship to offset the vertical component of tension induced in the tether line by the downwind force exerted by the turbine blades, a novel bearing assembly at the nose of the supporting airship which permits the airship to rotate as a unit with the turbine it supports without causing a similar rotation of the tether line, a novel turbine airship structure which handles concentrated loads from the turbine efficiently and also permits the safe use of hydrogen for buoyancy, a novel ''space frame'' structure which supports the turbine blades and greatly reduces blade weight, a novel system for controlling turbine blade angle of incidence and for varying blade incidene in synchrony with blade angular position abut the turbine axis to provide greater control over airship movement, a novel system for locating propellor-driven generators out at the wind turbine perimeter and for using lightweight, high-RPM generators to produce electrical energy at a power line frequency, which greatly reduces the weight required to convert turbine blade torque into useful power, and a novel system for incorporating compressed air storage and combustion turbine components into the wind turbine's generator drive systems.
Watson, W. K.
Energy 101: Wind Turbines - 2014 Update
See how wind turbines generate clean electricity from the power of wind. The video highlights the basic principles at work in wind turbines, and illustrates how the various components work to capture and convert wind energy to electricity. This updated version also includes information on the Energy Department's efforts to advance offshore wind power. Offshore wind energy footage courtesy of Vestas.
Probabilistic Analysis of LIST Data for the Estimation of Extreme Design Loads for Wind Turbine Components
Robust estimation of wind turbine design loads for service lifetimes of 30 to 50 years that are based on field measurements of a few days is a challenging problem. Estimating the long-term load distribution involves the integration of conditional distributions of extreme loads over the mean wind speed and turbulence intensity distributions. However, the accuracy of the statistical extrapolation is
M. D. Pandey; H. J. Sutherland
Wind turbine wake aerodynamics
The aerodynamics of horizontal axis wind turbine wakes is studied. The contents is directed towards the physics of power extraction by wind turbines and reviews both the near and the far wake region. For the near wake, the survey is restricted to uniform, steady and parallel flow conditions, thereby excluding wind shear, wind speed and rotor setting changes and yawed
L. J. Vermeer; J. N. S°rensen; A. Crespo
Wind turbine system
A wind turbine system utilizes a bicycle wheel type turbine having airfoils mounted on various spoke pairs. The vertical yaw axis lies in the horizontal projection of the airfoils to offer better control of the system; for example, automatic stowage in the case of excessive wind is provided since the superstructure of the turbine provides a torque around the vertical
Wind Turbine Noise
Following an introduction to noise and noise regulation of wind turbines, the problem of adverse health effects of turbine noise is discussed. This is attributed to the characteristics of turbine noise and deficiencies in the regulation of this noise. Both onshore and offshore wind farms are discussed.
John P. Harrison
Wind Turbines Benefit Crops
Ames Laboratory associate scientist Gene Takle talks about research into the effect of wind turbines on nearby crops. Preliminary results show the turbines may have a positive effect by cooling and drying the crops and assisting with carbon dioxide uptake.
Takle, Gene
Wind Turbine Blade
This photo shows one of the three 135-ft blades of a turbine before installation. Although the blades of wind turbines appear to move quite slowly to the human eye, blade tips often move at speeds faster than 100 mph. ...
Method and apparatus for wind turbine braking
A method for braking a wind turbine including at least one rotor blade coupled to a rotor. The method includes selectively controlling an angle of pitch of the at least one rotor blade with respect to a wind direction based on a design parameter of a component of the wind turbine to facilitate reducing a force induced into the wind turbine component as a result of braking.
Barbu, Corneliu (Laguna Hills, CA) [Laguna Hills, CA; Teichmann, Ralph (Nishkayuna, NY) [Nishkayuna, NY; Avagliano, Aaron (Houston, TX) [Houston, TX; Kammer, Leonardo Cesar (Niskayuna, NY) [Niskayuna, NY; Pierce, Kirk Gee (Simpsonville, SC) [Simpsonville, SC; Pesetsky, David Samuel (Greenville, SC) [Greenville, SC; Gauchel, Peter (Muenster, DE) [Muenster, DE
Small Wind Turbine Testing and Applications Development
Small wind turbines offer a promising alternative for many remote electrical uses where there is a good wind resource. The National Wind Technology Center (NWTC) of the National Renewable Energy Laboratory helps further the role that small turbines can play in supplying remote power needs. The NWTC tests and develops new applications for small turbines. The NWTC also develops components used in conjunction with wind turbines for various applications. This paper describes wind energy research at the NWTC for applications including battery charging stations, water desalination/purification, and health clinics. Development of data acquisition systems and tests on small turbines are also described.
Corbus, D.; Baring-Gould, I.; Drouilhet, S.; Gevorgian, V.; Jimenez, T.; Newcomb, C.; Flowers, L.
Advanced wind turbine design
Garrad Hassan have a project in progress funded by the U.K. Department of Trade and Industry (DTI) to assess the prospects and cost benefits of advanced wind turbine design. In the course of this work, a new concept, the coned rotor design, has been developed. This enables a wind turbine system to operate in effect with variable rotor diameter augmenting
P. M. Jamieson; A. Jaffrey
Vertical axis wind turbine
A Darrieus-type vertical axis wind turbine is disclosed which includes a vertically extending rotor tube mounted on a support structure with two or three rotor blades of troposkein configuration on the rotor tube for rotating the tube in response to wind energy and thereby drive a generator to produce electrical power. The turbine includes an erection hinge which permits assembly
Wind turbines at work
This paper describes how multimegawatt wind-turbine generators are being integrated with electric power systems in oil-dependent, wind-rich areas. Details are given on the wind turbines designed for the US DOE and operated by Pacific Gas and Electric in California and by the Bonneville Power Administration near Goldendale, Washington. It is shown how the Public Utility Regulatory Policies Act of 1978, requiring utilities to purchase power at fair rates from independent generators of wind, will encourage small operations and accelerate the use of wind power. Environmental problems include electromagnetic interference and noise pollution. Presents an annotated bibliography.
Cadogan, J.B.; Ancona, D.F.
Foundations for offshore wind turbines.
An important engineering challenge of today, and a vital one for the future, is to develop and harvest alternative sources of energy. This is a firm priority in the UK, with the government setting a target of 10% of electricity from renewable sources by 2010. A component central to this commitment will be to harvest electrical power from the vast energy reserves offshore, through wind turbines or current or wave power generators. The most mature of these technologies is that of wind, as much technology transfer can be gained from onshore experience. Onshore wind farms, although supplying 'green energy', tend to provoke some objections on aesthetic grounds. These objections can be countered by locating the turbines offshore, where it will also be possible to install larger capacity turbines, thus maximizing the potential of each wind farm location. This paper explores some civil-engineering problems encountered for offshore wind turbines. A critical component is the connection of the structure to the ground, and in particular how the load applied to the structure is transferred safely to the surrounding soil. We review previous work on the design of offshore foundations, and then present some simple design calculations for sizing foundations and structures appropriate to the wind-turbine problem. We examine the deficiencies in the current design approaches, and the research currently under way to overcome these deficiencies. Designs must be improved so that these alternative energy sources can compete economically with traditional energy suppliers. PMID:14667305
Byrne, B W; Houlsby, G T
Build a Wind Turbine
NSDL National Science Digital Library
Learners build a wind turbine and test it to see how much energy is created. Learners can build a variety of wind blades, test a variety of wind speeds and see what effect these have on the energy created. Adult supervision recommended.
Museum Of Science And Industry, Chicago
Wind Turbine Blade Design
Students go through the design process and the scientific method to test the effect of blade design on power output. There is an optional extension to use the data to create an optimal set of wind turbine blades.
Project, Kidwind
Garrad Hassan have a project in progress funded by the U.K. Department of Trade and Industry (DTI) to assess the prospects and cost benefits of advanced wind turbine design. In the course of this work, a new concept, the coned rotor design, has been developed. This enables a wind turbine system to operate in effect with variable rotor diameter augmenting energy capture in light winds and shedding loads in storm conditions. Comparisons with conventional design suggest that a major benefit in reduced cost of wind-generated electricity may be possible.
Jamieson, P.M.; Jaffrey, A. [Garrad Hassan and Partners, Ltd., Glasgow (United Kingdom)
Vertical axis wind turbines
A vertical axis wind turbine is described. The wind turbine can include a top ring, a middle ring and a lower ring, wherein a plurality of vertical airfoils are disposed between the rings. For example, three vertical airfoils can be attached between the upper ring and the middle ring. In addition, three more vertical airfoils can be attached between the lower ring and the middle ring. When wind contacts the vertically arranged airfoils the rings begin to spin. By connecting the rings to a center pole which spins an alternator, electricity can be generated from wind.
Krivcov, Vladimir (Miass, RU) [Miass, RU; Krivospitski, Vladimir (Miass, RU) [Miass, RU; Maksimov, Vasili (Miass, RU) [Miass, RU; Halstead, Richard (Rohnert Park, CA) [Rohnert Park, CA; Grahov, Jurij (Miass, RU) [Miass, RU
In this activity, learners design, build and test wind turbines. Learners go through the design process and use the scientific method to test important blade variables. Learners then use this data to create an optimal set of wind turbine blades. Educators can do the basic lesson in 3-4 class periods (about 3-4 hours) or extend the activity with a larger challenge that takes 5-7 class periods in total (about 5-7 hours).
Tutorial of Wind Turbine Control for Supporting Grid Frequency through Active Power Control: Preprint
As wind energy becomes a larger portion of the world's energy portfolio and wind turbines become larger and more expensive, wind turbine control systems play an ever more prominent role in the design and deployment of wind turbines. The goals of traditional wind turbine control systems are maximizing energy production while protecting the wind turbine components. As more wind generation
J. Aho; A. Buckspan; J. Laks; P. Fleming; Y. Jeong; F. Dunne; M. Churchfield; L. Pao; K. Johnson
Alcoa wind turbines
An overview of Alcoa's wind energy program is given with emphasis on the the development of a low cost, reliable Darrieus Vertical Axis Wind Turbine System. The design layouts and drawings for fabrication are now complete, while fabrication and installation to utilize the design are expected to begin shortly.
Ai, D. K.
Wind turbine with governor
A wind turbine assembly is described which comprises a supporting framework including a rigid elevated platform, a turntable rotatably supported from the platform for swivelling movement about a substantially vertical axis, a horizontal shaft rotatably journalled from the turntable with the end portions of the shaft projecting diametrically therefrom, a plurality of wind wheels mounted on each end of the
Theory manual for FAROW version 1.1: A numerical analysis of the Fatigue And Reliability Of Wind turbine components
Because the fatigue lifetime of wind turbine components depends on several factors that are highly variable, a numerical analysis tool called FAROW has been created to cast the problem of component fatigue life in a probabilistic framework. The probabilistic analysis is accomplished using methods of structural reliability (FORM/SORM). While the workings of the FAROW software package are defined in the user's manual, this theory manual outlines the mathematical basis. A deterministic solution for the time to failure is made possible by assuming analytical forms for the basic inputs of wind speed, stress response, and material resistance. Each parameter of the assumed forms for the inputs can be defined to be a random variable. The analytical framework is described and the solution for time to failure is derived.
Air flow behind wind turbines
Wind turbine wakes have been studied by analysing a large set of atomospheric data, from a wind farm with four turbines sited on a flat coastal area. The results obtained have been generalized to allow tests against data from other full scale wind turbines as well as wind tunnel simulations. These comparisons are found to give very satisfactory results. Most
M. Magnusson; A.-S. Smedman
Design of wind turbine controller by using wind turbine codes
The wind turbine codes predict wind turbine loads and response in high accuracy and can be used in controller design with the development of the computer technologies. In this paper open source FAST code developed by NREL is studied. The wind turbine controller is designed in the Matlab\\/Simulink environment and the FAST code is modeled as an S-function. The simulation
Jianzhong Zhang; Ming Cheng; Zhe Chen
Wind turbine aerodynamics and loads control in wind shear flow
Wind turbine is subjected to some asymmetrical effects like wind shear, which will lead to unsteady blade airloads and performance. Fatigue loads can lead to damage of turbine components and eventually to failures. It is evident that the variation of the velocity over the rotor disc has an influence on the blade and introduces both flap-wise and edge-wise fatigue damage
Xin Shen; Xiaocheng Zhu; Zhaohui Du
Predicting Noise From Wind Turbines
Computer program WINDY predicts broadband noise spectra of horizontal-axis wind-turbine generators. Enables adequate assessment of impact of broadband wind-turbine noise. Effects of turbulence, trailing-edge wakes, and bluntness taken into account. Program has practical application in design and siting of wind-turbine machines acceptable to community. Written in GW-Basic.
Grosveld, Ferdinand W.
Lightning protection system for a wind turbine
In a wind turbine (104, 500, 704) having a plurality of blades (132, 404, 516, 744) and a blade rotor hub (120, 712), a lightning protection system (100, 504, 700) for conducting lightning strikes to any one of the blades and the region surrounding the blade hub along a path around the blade hub and critical components of the wind turbine, such as the generator (112, 716), gearbox (708) and main turbine bearings (176, 724).
Costin, Daniel P. (Chelsea, VT) [Chelsea, VT; Petter, Jeffrey K. (Williston, VT) [Williston, VT
Airborne Wind Turbine
Broad Funding Opportunity Announcement Project: Makani Power is developing an Airborne Wind Turbine (AWT) that eliminates 90% of the mass of a conventional wind turbine and accesses a stronger, more consistent wind at altitudes of near 1,000 feet. At these altitudes, 85% of the country can offer viable wind resources compared to only 15% accessible with current technology. Additionally, the Makani Power wing can be economically deployed in deep offshore waters, opening up a resource which is 4 times greater than the entire U.S. electrical generation capacity. Makani Power has demonstrated the core technology, including autonomous launch, land, and power generation with an 8 meter wingspan, 20 kW prototype. At commercial scale, Makani Power aims to develop a 600 kW, 28 meter wingspan product capable of delivering energy at an unsubsidized cost competitive with coal, the current benchmark for low-cost power.
Tornado type wind turbines
A tornado type wind turbine has a vertically disposed wind collecting tower with spaced apart inner and outer walls and a central bore. The upper end of the tower is open while the lower end of the structure is in communication with a wind intake chamber. An opening in the wind chamber is positioned over a turbine which is in driving communication with an electrical generator. An opening between the inner and outer walls at the lower end of the tower permits radially flowing air to enter the space between the inner and outer walls while a vertically disposed opening in the wind collecting tower permits tangentially flowing air to enter the central bore. A porous portion of the inner wall permits the radially flowing air to interact with the tangentially flowing air so as to create an intensified vortex flow which exits out of the top opening of the tower so as to create a low pressure core and thus draw air through the opening of the wind intake chamber so as to drive the turbine.
Hsu, Cheng-Ting (Ames, IA) [Ames, IA
Wind Turbine Fatigue Considerations.
Current methods of analyzing wind turbine fatigue life are reviewed and found to be inadequate. One reason for this inadequacy is that these methods treat material fatigue properties as well-defined values, when they are, in fact, more accurately describe...
D. Berg
Wind turbine spoiler
An aerodynamic spoiler system for a vertical axis wind turbine includes spoilers on the blades initially stored near the rotor axis to minimize drag. A solenoid latch adjacent the central support tower releases the spoilers and centrifugal force causes the spoilers to move up the turbine blades away from the rotor axis, thereby producing a braking effect and actual slowing of the associated wind turbine, if desired. The spoiler system can also be used as an infinitely variable power control by regulated movement of the spoilers on the blades over the range between the undeployed and fully deployed positions. This is done by the use of a suitable powered reel and cable located at the rotor tower to move the spoilers.
Sullivan, William N. (Albuquerque, NM) [Albuquerque, NM
Identification of inflow fluid dynamics parameters that can be used to scale fatigue loading spectra of wind turbine structural components.
We have recently shown that the alternating load fatigue distributions measured at several locations on a wind turbine operating in a turbulent flow can be described by a mixture of at least three parametric statistical models. The rainflow cycle counting...
A wind turbine, by use of a tethered airship for support, may be designed for the economical recovery of power at heights of 2,000 feet or more above ground, at which height power density in the wind is typically three times the power density available to a conventionally supported wind turbine. Means can be added to such an airship-floated wind
The identification of inflow fluid dynamics parameters that can be used to scale fatigue loading spectra of wind turbine structural components
We have recently shown that the alternating load fatigue distributions measured at several locations on a wind turbine operating in a turbulent flow can be described by a mixture of at least three parametric statistical models. The rainflow cycle counting of the horizontal and vertical inflow components results in a similar mixture describing the cyclic content of the wind. We believe such a description highlights the degree of non-Gaussian characteristics of the flow. We present evidence that the severity of the low-cycle, high-amplitude alternating stress loads seen by wind turbine components are a direct consequence of the degree of departure from normality in the inflow. We have examined the details of the turbulent inflow associated with series large loading events that took place on two adjacent wind turbines installed in a large wind park in San Gorgonio Pass, California. In this paper, we describe what we believe to be the agents in the flow that induced such events. We also discuss the atmospheric mechanisms that influence the low-cycle, high-amplitude range loading seen by a number of critical wind turbine components. We further present results that can be used to scale the specific distribution shape as functions of measured inflow fluid dynamics parameters.
Kelley, N. D.
Stability Simulation of Wind Turbine Systems
A simulation and digital computer modeling effort is described in which a wind turbine-generator system is adapted for stability evaluation using a large scale transient stability computer program. Component models of the MOD-2 wind generator system are described and their digital model equations are provided. A versatile wind velocity model is described, which provides the capability of simulating a wide
P. M. Anderson; Anjan Bose
This hands-on project provides step-by-step instructions for building a vertical axis wind turbine in secondary classrooms. The 17-page construction plans may be freely downloaded and are organized for first-time builders. Comprehensive background information on wind energy and renewable energy are provided. Registered teacher-users also have access to supporting lesson plans. All of the materials are readily available in hardware or grocery stores. This resource, which meets multiple national science standards, was developed to spark students' interest in learning more about renewable energy sources and the science and engineering principles that underlie the harnessing of renewable power. Editor's Note: Wind turbines work by using an internal generator to convert the mechanical energy of the spinning turbine shaft into electricity. This particular project is modeled after the Savonius rotor system, which uses uses drag -- not lift -- to capture energy for making electricity. Although it isn't as efficient as a conventional horizontal axis turbine, it is much easier to build.
A simulation model for wind turbine blade fatigue loads
The paper describes a horizontal axis wind turbine time domain simulation and fatigue estimation program written using the DelphiTM language. The program models the flapwise motion of a single rotor blade to determine the blade-root fatigue damage of a medium size wind turbine. The effects of turbulence intensity, mean wind speed, wind shear, vertical wind component, dynamic stall, stall hysteresis,
M. Noda; R. G. J. Flay
Wind Turbine With Concentric Ducts
Wind Turbine device is relatively compact and efficient. Converging inner and outer ducts increase pressure difference across blades of wind turbine. Turbine shaft drives alternator housed inside exit cone. Suitable for installation on such existing structures as water towers, barns, houses, and commercial buildings.
Muhonen, A. J.
Wind turbine acoustic standards
A program is being conducted to develop noise standards for wind turbines which minimize annoyance and which can be used to design specifications. The approach consists of presenting wind turbine noise stimuli to test subjects in a laboratory listening chamber. The responses of the subjects are recorded for a range of stimuli which encompass the designs, operating conditions, and ambient noise levels of current and future installations. Results to date have established the threshold of detectability for a range of impulsive stimuli of the type associated with blade/tower wake interactions. The status of the ongoing psychoacoustic tests, the subjective data, and the approach to the development of acoustic criteria/standards are described.
Stephens, D. G.; Shepherd, K. P.; Grosveld, F.
Optimum propeller wind turbines
The Prandtl-Betz-Theodorsen theory of heavily loaded airscrews has been adapted to the design of propeller windmills which are to be optimized for maximum power coefficient. It is shown that the simpler, light-loading, constant-area wake assumption can generate significantly different ''optimum'' performance and geometry, and that it is therefore not appropriate to the design of propeller wind turbines when operating in their normal range of high-tip-speed-to-wind-speed ratio. Design curves for optimum power coefficient are presented and an example of the design of a typical two-blade optimum rotor is given.
Sanderson, R.J.; Archer, R.D.
Airfoils for wind turbine
Airfoils for the blade of a wind turbine wherein each airfoil is characterized by a thickness in a range from 16%-24% and a maximum lift coefficient designed to be largely insensitive to roughness effects. The airfoils include a family of airfoils for a blade 15 to 25 meters in length, a family of airfoils for a blade 1 to 5 meters in length, and a family of airfoils for a blade 5 to 10 meters in length.
Tangler, James L. (Boulder, CO); Somers, Dan M. (State College, PA)
Airfoils are disclosed for the blade of a wind turbine wherein each airfoil is characterized by a thickness in a range from 16%-24% and a maximum lift coefficient designed to be largely insensitive to roughness effects. The airfoils include a family of airfoils for a blade 15 to 25 meters in length, a family of airfoils for a blade 1 to 5 meters in length, and a family of airfoils for a blade 5 to 10 meters in length. 10 figs.
Tangler, J.L.; Somers, D.M.
Smart structure for small wind turbine blade
Wind energy is seen as a viable alternative energy option for future energy demand. The blades of wind turbines are generally regarded as the most critical component of the wind turbine system. Ultimately, the blades act as the prime mover of the whole system which interacts with the wind flow during the production of energy. During wind turbine operation the wind loading cause the deflection of the wind turbine blade which can be significant and affect the turbine efficiency. Such a deflection in wind blade not only will result in lower performance in electrical power generation but also increase of material degradation due high fatigue life and can significantly shorten the longevity for the wind turbine material. In harnessing stiffness of the blade will contribute massive weight factor and consequently excessive bending moment. To overcome this excessive deflection due to wind loading on the blade, it is feasible to use shape memory alloy (SMA) wires which has ability take the blade back to its optimal operational shape. This paper details analytical and experimental work being carried out to minimize blade flapping deflection using SMA.
Supeni, E. E.; Epaarachchi, J. A.; Islam, M. M.; Lau, K. T.
Make Your Own Wind Turbine
In this activity, learners create a wind turbine model using a simple pattern, a thumbtack, and a pencil with an eraser. After constructing the model, learners blow on the wind turbine to simulate the wind. Use this activity to introduce alternative energy and electricity generation.
History, National M.
Small Wind Turbine Technology Assessment.
The result of the study carried out under the scope of the ATYCA project Test Plant of Wind Systems for Isolated Applications, about the state of art of the small wind turbine technology (wind turbines with swept area smaller than 40 m''2) is presented. T...
F. Avia Aranda I. Cruz Cruz
SERI advanced wind turbine blades
The primary goal of the Solar Energy Research Institute's (SERI) advanced wind turbine blades is to convert the kinetic energy in the wind into mechanical energy in an inexpensive and efficient manner. To accomplish this goal, advanced wind turbine blades have been developed by SERI that utilize unique airfoil technology. Performance characteristics of the advanced blades were verified through atmospheric
J. Tangler; B. Smith; D. Jager
Wind turbines power curve variability
A comprehensive measurement programme was carried through 300 kW Nordtank stall-regulated horizontal axis wind turbine. These turbines were erected at the test station for windmills by Hurghada Wind Energy Technology Centre. To the extent necessary to understand the measurement carried out, all experimental set up systems must be described. This paper describes the annual wind speed variability in Hurghada city
Mohammed G. Khalfallah; Aboelyazied M. Koliub
Aeroacoustics of large wind turbines
This paper reviews published information on aerodynamically generated noise from large horizontal axis wind turbines operated for electric power generation. Methods are presented for predicting both the discrete frequency rotational noise components and the broadband noise components, and results are compared with measurements. Refraction effects that result in the formation of high-frequency shadow zones in the upwind direction and channeling effects for the low frequencies in the downwind direction are illustrated. Special topics such as distributed source effects in prediction and the role of building dynamics in perception are also included.
Lightning protection of wind turbines
Possible damages to wind turbine components due to lightning strikes are discussed and means to prevent the damage are presented. A low resistance path to the ground is noted to be essential for any turbine system, including metal paths on nonmetal blades to conduct the strike. Surge arrestors are necessary to protect against overvoltages both from utility lines in normal operation and against lightning damage to control equipment and contactors in the generator. MOS structures are susceptible to static discharge injury, as are other semiconductor devices, and must be protected by the presence of static protection circuitry. It is recommended that the electronics be analyzed for the circuit transient response to a lightning waveform, to induced and dc current injection, that input/output leads be shielded, everything be grounded, and lightning-resistant components be chosen early in the design phase.
Dodd, C. W.
Large-scale wind turbine structures
The purpose of this presentation is to show how structural technology was applied in the design of modern wind turbines, which were recently brought to an advanced stage of development as sources of renewable power. Wind turbine structures present many difficult problems because they are relatively slender and flexible; subject to vibration and aeroelastic instabilities; acted upon by loads which are often nondeterministic; operated continuously with little maintenance in all weather; and dominated by life-cycle cost considerations. Progress in horizontal-axis wind turbines (HAWT) development was paced by progress in the understanding of structural loads, modeling of structural dynamic response, and designing of innovative structural response. During the past 15 years a series of large HAWTs was developed. This has culminated in the recent completion of the world's largest operating wind turbine, the 3.2 MW Mod-5B power plane installed on the island of Oahu, Hawaii. Some of the applications of structures technology to wind turbine will be illustrated by referring to the Mod-5B design. First, a video overview will be presented to provide familiarization with the Mod-5B project and the important components of the wind turbine system. Next, the structural requirements for large-scale wind turbines will be discussed, emphasizing the difficult fatigue-life requirements. Finally, the procedures used to design the structure will be presented, including the use of the fracture mechanics approach for determining allowable fatigue stresses.
Spera, David A.
Periodic pulsations from a three-bladed wind turbine
In this paper, periodic power pulsations from a three-bladed wind turbine are analyzed. The influence of wind shear, wind speed, turbulence intensity, rotor position and tower oscillation is investigated. No clear dependence between the periodic power components and the wind shear or turbulence intensity has been verified. The investigated turbine sometimes produces large power pulsations at the tower resonance frequency.
Torbj÷rn Thiringer; Jan-┼ke Dahlberg
Development of Wind Turbine Simulators Using PSCAD
In this paper, a wind turbine simulator is developed using PSCAD. The wind turbine static characteristics are modeled using the relation among the turbine power, the wind speed, and the blade pitch angle. Also, the dynamic characteristics of the wind turbine are modeled through a two-mass oscillating system, representing the turbine and the generator connected by elastic shaft. The system
A. G. Abo-Khalil
Superconducting wind turbine generators
We have examined the potential of 10 MW superconducting direct drive generators to enter the European offshore wind power market and estimated that the production of about 1200 superconducting turbines until 2030 would correspond to 10% of the EU offshore market. The expected properties of future offshore turbines of 8 and 10 MW have been determined from an up-scaling of an existing 5 MW turbine and the necessary properties of the superconducting drive train are discussed. We have found that the absence of the gear box is the main benefit and the reduced weight and size is secondary. However, the main challenge of the superconducting direct drive technology is to prove that the reliability is superior to the alternative drive trains based on gearboxes or permanent magnets. A strategy of successive testing of superconducting direct drive trains in real wind turbines of 10 kW, 100 kW, 1 MW and 10 MW is suggested to secure the accumulation of reliability experience. Finally, the quantities of high temperature superconducting tape needed for a 10 kW and an extreme high field 10 MW generator are found to be 7.5 km and 1500 km, respectively. A more realistic estimate is 200-300 km of tape per 10 MW generator and it is concluded that the present production capacity of coated conductors must be increased by a factor of 36 by 2020, resulting in a ten times lower price of the tape in order to reach a realistic price level for the superconducting drive train.
Abrahamsen, A. B.; Mijatovic, N.; Seiler, E.; Zirngibl, T.; Trµholt, C.; N°rgÕrd, P. B.; Pedersen, N. F.; Andersen, N. H.; žstergÕrd, J.
Towers for Offshore Wind Turbines
Increasing energy demand coupled with pollution free production of energy has found a viable solution in wind energy. Land based windmills have been utilized for power generation for more than two thousand years. In modern times wind generated power has become popular in many countries. Offshore wind turbines are being used in a number of countries to tap the energy from wind over the oceans and convert to electric energy. The advantages of offshore wind turbines as compared to land are that offshore winds flow at higher speed than onshore winds and the more available space. In some land based settings, for better efficiency, turbines are separated as much as 10 rotor diameters from each other. In offshore applications where only two wind directions are likely to predominate, the distances between the turbines arranged in a line can be shortened to as little as two or four rotor diameters. Today, more than a dozen offshore European wind facilities with turbine ratings of 450 kw to 3.6 MW exist offshore in very shallow waters of 5 to 12 m. Compared to onshore wind turbines, offshore wind turbines are bigger and the tower height in offshore are in the range of 60 to 80 m. The water depths in oceans where offshore turbines can be located are within 30 m. However as the distance from land increases, the costs of building and maintaining the turbines and transmitting the power back to shore also increase sharply. The objective of this paper is to review the parameters of design for the maximum efficiency of offshore wind turbines and to develop types offshore towers to support the wind turbines. The methodology of design of offshore towers to support the wind turbine would be given and the environmental loads for the design of the towers would be calculated for specific cases. The marine corrosion on the towers and the methods to control the corrosion also would be briefly presented. As the wind speeds tend to increase with distance from the shore, turbines build father offshore will be able to capture more wind energy. Currently two types of towers are considered. Cylindrical tubular structures and truss type structures. But truss type structures have less weight and flexibility in design. The construction of the offshore towers to harness the wind energy is also presented. The results will include the calculation of wind and wave forces on the tower and the design details for the tower.
Kurian, V. J.; Narayanan, S. P.; Ganapathy, C.
Strength and Reliability of Wood for the Components of Low-cost Wind Turbines: Computational and Experimental Analysis and Applications
This paper reports the latest results of the comprehensive program of experimental and computational analysis of strength and reliability of wooden parts of low cost wind turbines. The possibilities of prediction of strength and reliability of different types of wood are studied in the series of experiments and computational investigations. Low cost testing machines have been designed, and employed for
Leon Mishnaevsky Jr; Ranjan Sharma; Hai Qing; Jakob I. Bech; Rakesh Sinha; Robert Evans; Bhatti Danda; Parash Acharya
Wind tunnel investigation on wind turbine wakes and wind farms
The interaction between atmospheric boundary layer and wind farms leads to flow modifications, which need to be deeply characterized in order to relate them to wind farm performance. The wake flow produced from a wind farm is the result of a strong interaction between multiple turbine wakes, so that the wind farm configuration turns out to be one of the dominant features to enhance power production. For the present work a wind tunnel investigation was carried out with hot-wire anemometry and velocity measurements performed with multi-hole pressure probes. The tested wind farms consist of miniature three-bladed wind turbine models. Preliminarily, the wake flow generated from a single wind turbine is surveyed, which is characterized by a strong velocity defect lying in proximity of the wind turbine hub height. The wake gradually recovers by moving downstream; the characteristics of the incoming boundary layer and wind turbulence intensity can strongly affect the wake recovery, and thus performance of following wind turbines. An increased turbulence level is typically detected downstream of each wind turbine for heights comparable to the wind turbine blade top-tip. These wake flow fluctuations produce increased fatigue loads on the following wind turbines within a wind farm, which could represent a significant hazard for real wind turbines. Dynamics of vorticity structures present in wind turbine wakes are also investigated; particular attention is paid to the downstream evolution of the tip helicoidal vortices and to oscillations of the hub vortex. The effect of wind farm layout on power production is deeply investigated. Particular emphasis is placed on studying how the flow adjusts as it moves inside the wind farm and can affect the power production. Aligned and staggered wind farm configurations are analysed, also with varying separation distances in the streamwise and spanwise directions. The present experimental results are being used to test and guide the development of improved parameterizations of wind turbines in high-resolution numerical models, such as large-eddy simulations (LES).
Iungo, G. V.; Coļffķ, J.; Portķ-Agel, F.
Modal analysis of wind turbine tower
As the support structure of wind turbine, the tower bears alternating loads of wind when the wind turbine runs. To ensure the reliability of the wind turbine, it's necessary to carry out modal analysis on the tower, and this would prevent the natural frequency of the tower close to the rated speed of wind turbine. In this paper, finite element
Jie Chen; Dongxiang Jiang
Chapter 14: Wind Turbine Control Systems
Wind turbines are complex, nonlinear, dynamic systems forced by gravity, stochastic wind disturbances, and gravitational, centrifugal, and gyroscopic loads. The aerodynamic behavior of wind turbines is nonlinear, unsteady, and complex. Turbine rotors are subjected to a complicated three-dimensional turbulent wind inflow field that drives fatigue loading. Wind turbine modeling is also complex and challenging. Accurate models must contain many degrees
A Review of Modern Wind Turbine Technology
This article deals with a review of modern wind turbine technology. Wind energy for electricity production today is a mature, competitive, and virtually pollution-free technology widely used in many areas of the world. Wind technology converts the energy available in wind to electricity or mechanical power through the use of wind turbines. A wind turbine is a machine for converting
M. Balat
PowerJet Wind Turbine Project
PROJECT OBJECTIVE The PowerJet wind turbine overcomes problems characteristic of the small wind turbines that are on the market today by providing reliable output at a wide range of wind speeds, durability, silent operation at all wind speeds, and bird-safe operation. Prime Energy├ó┬?┬?s objective for this project was to design and integrate a generator with an electrical controller and mechanical controls to maximize the generation of electricity by its wind turbine. The scope of this project was to design, construct and test a mechanical back plate to control rotational speed in high winds, and an electronic controller to maximize power output and to assist the base plate in controlling rotational speed in high winds. The test model will continue to operate beyond the time frame of the project, with the ultimate goal of manufacturing and marketing the PowerJet worldwide. Increased Understanding of Electronic & Mechanical Controls Integrated With Electricity Generator The PowerJet back plate begins to open as wind speed exceeds 13.5 mps. The pressure inside the turbine and the turbine rotational speed are held constant. Once the back plate has fully opened at approximately 29 mps, the controller begins pulsing back to the generator to limit the rotational speed of the turbine. At a wind speed in excess of 29 mps, the controller shorts the generator and brings the turbine to a complete stop. As the wind speed subsides, the controller releases the turbine and it resumes producing electricity. Data collection and instrumentation problems prevented identification of the exact speeds at which these events occur. However, the turbine, controller and generator survived winds in excess of 36 mps, confirming that the two over-speed controls accomplished their purpose. Technical Effectiveness & Economic Feasibility Maximum Electrical Output The output of electricity is maximized by the integration of an electronic controller and mechanical over-speed controls designed and tested during the course of this project. The output exceeds that of the PowerJet├ó┬?┬?s 3-bladed counterparts (see Appendix). Durability All components of the PowerJet turbine assembly├ó┬?┬?including the electronic and mechanical controls designed, manufactured and field tested during the course of this project├ó┬?┬?proved to be durable through severe weather conditions, with constant operation and no interruption in energy production. Low Cost Materials for the turbine, generator, tower, charge controllers and ancillary parts are available at reasonable prices. Fabrication of these parts is also readily available worldwide. The cost of assembling and installing the turbine is reduced because it has fewer parts and requires less labor to manufacture and assemble, making it competitively priced compared with turbines of similar output manufactured in the U.S. and Europe. The electronic controller is the unique part to be included in the turbine package. The controllers can be manufactured in reasonably-sized production runs to keep the cost below $250 each. The data logger and 24 sensors are for research only and will be unnecessary for the commercial product. Benefit To Public The PowerJet wind-electric system is designed for distributed wind generation in 3 and 4 class winds. This wind turbine meets DOE├ó┬?┬?s requirements for a quiet, durable, bird-safe turbine that eventually can be deployed as a grid-connected generator in urban and suburban settings. Results As described more fully below and illustrated in the Appendices, the goals and objectives outlined in 2060 SOPO were fully met. Electronic and mechanical controls were successfully designed, manufactured and integrated with the generator. The turbine, tower, controllers and generators operated without incident throughout the test period, surviving severe winter and summer weather conditions such as extreme temperatures, ice and sustained high winds. The electronic controls were contained in weather-proof electrical boxes and the elec
Bartlett, Raymond J
Augmented adaptive control of a wind turbine in the presence of structural modes
Wind turbines operate in highly turbulent environments resulting in aerodynamic loads that can easily excite turbine structural modes, potentially causing component fatigue and failure. Two key technology drivers for turbine manufacturers are increasing turbine up time and reducing maintenance costs. Since the trend in wind turbine design is towards larger, more flexible turbines with lower frequency structural modes, manufacturers will
Susan A. Frost; Mark J. Balas; Alan D. Wright
Effective Lightning Protection For Wind Turbine Generators
A wind turbine generator is the most exposed of all types of generators connected to electric utility systems. Wind turbines are most often erected in hostile lightning environments. Lightning damage to wind turbines is costly in terms of repair and replacement of equipment. Lightning damage is the single largest cause of unplanned downtime in wind turbines, and that downtime is
Bruce Glushakow
Wind turbine rotor aileron
A wind turbine has a rotor with at least one blade which has an aileron which is adjusted by an actuator. A hinge has two portions, one for mounting a stationary hinge arm to the blade, the other for coupling to the aileron actuator. Several types of hinges can be used, along with different actuators. The aileron is designed so that it has a constant chord with a number of identical sub-assemblies. The leading edge of the aileron has at least one curved portion so that the aileron does not vent over a certain range of angles, but vents if the position is outside the range. A cyclic actuator can be mounted to the aileron to adjust the position periodically. Generally, the aileron will be adjusted over a range related to the rotational position of the blade. A method for operating the cyclic assembly is also described.
Coleman, Clint (Warren, VT) [Warren, VT; Kurth, William T. (Warren, VT) [Warren, VT
Wind and solar powered turbine
A power generating station having a generator driven by solar heat assisted ambient wind is described. A first plurality of radially extendng air passages direct ambient wind to a radial flow wind turbine disposed in a centrally located opening in a substantially disc-shaped structure. A solar radiation collecting surface having black bodies is disposed above the fist plurality of air
I. D. Wells; J. L. Koh; M. Holmes
Analysis of the Environmental Impact on Remanufacturing Wind Turbines
To deliver clean energy the use of wind turbines is essential. In June 2011 there was an installed wind capacity equivalent to 211,000MW world-wide (WWEA, 2011). By the end of the year 2009 the U.S. had 35,100MW of wind energy installed capacity to generate electricity (AWEA, 2010). This industry has grown in recent years and is expected to grow even more in the future. The environmental impacts that will arise from the increased number of wind turbines and their end-of-life should be addressed, as large amounts of resources will be required to satisfy the current and future market demands for wind turbines. Since future 10MW wind turbines are expected to be as heavy as 1000 tons each, the study of the environmental response of profitable retirement strategies, such as remanufacturing for these machines, must be considered. Because of the increased number of wind turbines and the materials used, this study provides a comparison between the environmental impacts from remanufacturing the components installed inside the nacelle of multi-megawatt wind turbines and wind turbines manufactured using new components. The study methodology is the following: Ģ Describe the life-cycle and the materials and processes employed for the manufacture and remanufacturing for components inside the nacelle. Ģ Identify remanufacturing alternatives for the components inside the nacelle at the end of the expected life-time service of wind turbines. Ģ Evaluate the environmental impacts from the remanufactured components and compare the results with the impacts of the manufacturing of new components using SimaPro. Ģ Conduct sensitivity analysis over the critical parameters of the life cycle assessment Ģ Propose the most environmentally friendly options for the retirement of each major component of wind turbines. After an analysis of the scenarios the goal of the study is to evaluate remanufacturing as an end-of-life option from an environmental perspective for commercial multi-megawatt wind turbines targeted for secondary wind turbine markets.
Sosa Skrainka, Manuel R.
Wind Turbine Drivetrain Condition Monitoring-An Overview.
High operation and maintenance costs still hamper the development of the wind industry despite its quick growth worldwide. To reduce unscheduled downtime and avoid catastrophic failures of wind turbines and their components have been and will be crucial t...
S. Sheng W. Yang
Sprayed skin turbine component
Fabricating a turbine component (50) by casting a core structure (30), forming an array of pits (24) in an outer surface (32) of the core structure, depositing a transient liquid phase (TLP) material (40) on the outer surface of the core structure, the TLP containing a melting-point depressant, depositing a skin (42) on the outer surface of the core structure over the TLP material, and heating the assembly, thus forming both a diffusion bond and a mechanical interlock between the skin and the core structure. The heating diffuses the melting-point depressant away from the interface. Subsurface cooling channels (35) may be formed by forming grooves (34) in the outer surface of the core structure, filling the grooves with a fugitive filler (36), depositing and bonding the skin (42), then removing the fugitive material.
Allen, David B
Siting technologies for large wind turbine clusters
Site selection for large wind turbine clusters requires thorough documentation of the wind characteristics at the site, because of the influence these characteristics will have on the economics, operations, and service life of the wind turbines. The wind prospecting strategy can be used by a utility to determine specific locations for each wind turbine in a cluster of 10 to
T. R. Hiester; W. T. Pennell
Airfoil characteristics for wind turbines.
Airfoil characteristics for use in the Blade Element Momentum (BEM) method calculating the forces on Horizontal Axis Wind Turbines (HAWT) are derived by use of systematic methods. The investigation and derivation of the airfoil characteristics are based o...
C. Bak P. Fuglsang N. N. Soerensen H. Aagaard Madsen Wen Zhong Shen
Wind Turbine Manufacturing Process Monitoring.
To develop a practical inline inspection that could be used in combination with automated composite material placement equipment to economically manufacture high performance and reliable carbon composite wind turbine blade spar caps. The approach technica...
C. Nafis C. Yerramalli J. Gangloff P. Simacek S. Advani S. Sinha W. Faidi
Twin Turbine Vortex Wind Mill.
The twin turbine vortex wind mill consists of a pair of multibladed rotors placed at the ends of a hollow cylindrical cage which is specially designed to produce vortex motion. Both the turbines are coupled to a single vertical shaft from which rotary mec...
M. A. B. Narayanan
Wind Turbine Certification and Type Certification Guideline for the Certification of Wind Turbines, Edition 2003 with Supplement 2004
Certification of wind turbines or components is state-of-the-art and a must in most places around the world. Furthermore certification to harmonised requirements is an active support of export. Therefore it is important for manufacturers, banks and insurances of wind turbines and components to know the different certification processes as well as guidelines. The procedures to obtain Type and Project Certificates
Mike Woebbeking; Christian Nath; Germanischer Lloyd
A power generating station having a generator driven by solar heat assisted ambient wind is described. A first plurality of radially extendng air passages direct ambient wind to a radial flow wind turbine disposed in a centrally located opening in a substantially disc-shaped structure. A solar radiation collecting surface having black bodies is disposed above the fist plurality of air passages and in communication with a second plurality of radial air passages. A cover plate enclosing the second plurality of radial air passages is transparent so as to permit solar radiation to effectively reach the black bodies. The second plurality of air passages direct ambient wind and thermal updrafts generated by the black bodies to an axial flow turbine. The rotating shaft of the turbines drive the generator. The solar and wind drien power generating system operates in electrical cogeneration mode with a fuel powered prime mover.
Wells, I. D.; Koh, J. L.; Holmes, M. (inventors)
Unavailability of wind turbines due to wind-induced accelerations
The malfunctioning of acceleration-sensitive equipment in wind turbines has the potential to affect their annual failure rates during normal operating conditions. Current protective measures for wind turbines are triggered by wind speed. However, this option neglects the structural response of the wind turbines, and limits the possibility of effectively controlling accelerations at the top of the wind towers. In this
Leonardo Due±as-Osorio; Biswajit Basu
Airfoils for the tip and mid-span regions of a wind turbine blade have upper surface and lower surface shapes and contours between a leading edge and a trailing edge that minimize roughness effects of the airfoil and provide maximum lift coefficients that are largely insensitive to roughness effects. The airfoil in one embodiment is shaped and contoured to have a thickness in a range of about fourteen to seventeen percent, a Reynolds number in a range of about 1,500,000 to 2,000,000, and a maximum lift coefficient in a range of about 1.4 to 1.5. In another embodiment, the airfoil is shaped and contoured to have a thickness in a range of about fourteen percent to sixteen percent, a Reynolds number in a range of about 1,500,000 to 3,000,000, and a maximum lift coefficient in a range of about 0.7 to 1.5. Another embodiment of the airfoil is shaped and contoured to have a Reynolds in a range of about 1,500,000 to 4,000,000, and a maximum lift coefficient in a range of about 1.0 to 1.5.
Tangler, James L. (Boulder, CO) [Boulder, CO; Somers, Dan M. (State College, PA) [State College, PA
RCS measurement of wind turbines
A set of measurements has recently been undertaken in the UK with the aim of determining the RCS (Radar Cross Section) of typical wind turbines, both in an isolated location, and within a wind farm. The measurements made use of a triband channel sounder, employing 10 MChip\\/s PN sequence with off-line correlation. The results from this campaign are presented, with
Richard Rudd; Bal Rhandawa
Improving Wind Turbine Gearbox Reliability
+1 207 326 7148 Summary This paper describes a new research and development initiative to improve gearbox reliability in wind turbines begun at the National Renewable Energy Laboratory (NREL) in Golden, Colorado, USA. The approach involves a collaboration of NREL staff, expert consultants, and partners from the wind energy industry who have an interest in improving gearbox reliability. The membership
W. Musial; S. Butterfield; B. McNiff
Dynamics and stability of wind turbine generators
Synchronous and induction generators are considered. A comparison is made between wind turbines, steam, and hydro units. The unusual phenomena associated with wind turbines are emphasized. The general control requirements are discussed, as well as various schemes for torsional damping such as speed sensitive stabilizer and blade pitch control. Integration between adjacent wind turbines in a wind farm is also considered.
Hinrichsen, E. N.; Nolan, P. J.
Sandia Wind Turbine Loads Database
DOE Data Explorer
The Sandia Wind Turbine Loads Database is divided into six files, each corresponding to approximately 16 years of simulation. The files are text files with data in columnar format. The 424MB zipped file containing six data files can be downloaded by the public. The files simulate 10-minute maximum loads for the NREL 5MW wind turbine. The details of the loads simulations can be found in the paper: ōDecades of Wind Turbine Loads Simulationsö, M. Barone, J. Paquette, B. Resor, and L. Manuel, AIAA2012-1288 (3.69MB PDF). Note that the site-average wind speed is 10 m/s (class I-B), not the 8.5 m/s reported in the paper.
Wind Turbines and Human Health
PubMed Central
The association between wind turbines and health effects is highly debated. Some argue that reported health effects are related to wind turbine operation [electromagnetic fields (EMF), shadow flicker, audible noise, low-frequency noise, infrasound]. Others suggest that when turbines are sited correctly, effects are more likely attributable to a number of subjective variables that result in an annoyed/stressed state. In this review, we provide a bibliographic-like summary and analysis of the science around this issue specifically in terms of noise (including audible, low-frequency noise, and infrasound), EMF, and shadow flicker. Now there are roughly 60 scientific peer-reviewed articles on this issue. The available scientific evidence suggests that EMF, shadow flicker, low-frequency noise, and infrasound from wind turbines are not likely to affect human health; some studies have found that audible noise from wind turbines can be annoying to some. Annoyance may be associated with some self-reported health effects (e.g., sleep disturbance) especially at sound pressure levels >40?dB(A). Because environmental noise above certain levels is a recognized factor in a number of health issues, siting restrictions have been implemented in many jurisdictions to limit noise exposure. These setbacks should help alleviate annoyance from noise. Subjective variables (attitudes and expectations) are also linked to annoyance and have the potential to facilitate other health complaints via the nocebo effect. Therefore, it is possible that a segment of the population may remain annoyed (or report other health impacts) even when noise limits are enforced. Based on the findings and scientific merit of the available studies, the weight of evidence suggests that when sited properly, wind turbines are not related to adverse health. Stemming from this review, we provide a number of recommended best practices for wind turbine development in the context of human health.
Knopper, Loren D.; Ollson, Christopher A.; McCallum, Lindsay C.; Whitfield Aslund, Melissa L.; Berger, Robert G.; Souweine, Kathleen; McDaniel, Mary
Wind turbines and human health.
The association between wind turbines and health effects is highly debated. Some argue that reported health effects are related to wind turbine operation [electromagnetic fields (EMF), shadow flicker, audible noise, low-frequency noise, infrasound]. Others suggest that when turbines are sited correctly, effects are more likely attributable to a number of subjective variables that result in an annoyed/stressed state. In this review, we provide a bibliographic-like summary and analysis of the science around this issue specifically in terms of noise (including audible, low-frequency noise, and infrasound), EMF, and shadow flicker. Now there are roughly 60 scientific peer-reviewed articles on this issue. The available scientific evidence suggests that EMF, shadow flicker, low-frequency noise, and infrasound from wind turbines are not likely to affect human health; some studies have found that audible noise from wind turbines can be annoying to some. Annoyance may be associated with some self-reported health effects (e.g., sleep disturbance) especially at sound pressure levels >40?dB(A). Because environmental noise above certain levels is a recognized factor in a number of health issues, siting restrictions have been implemented in many jurisdictions to limit noise exposure. These setbacks should help alleviate annoyance from noise. Subjective variables (attitudes and expectations) are also linked to annoyance and have the potential to facilitate other health complaints via the nocebo effect. Therefore, it is possible that a segment of the population may remain annoyed (or report other health impacts) even when noise limits are enforced. Based on the findings and scientific merit of the available studies, the weight of evidence suggests that when sited properly, wind turbines are not related to adverse health. Stemming from this review, we provide a number of recommended best practices for wind turbine development in the context of human health. PMID:24995266
Knopper, Loren D; Ollson, Christopher A; McCallum, Lindsay C; Whitfield Aslund, Melissa L; Berger, Robert G; Souweine, Kathleen; McDaniel, Mary
Towards Data-Driven Control for Modern Wind Turbines
Further developments in data-driven control techniques for the load reduction of modern wind turbines can achieve an increased lifetime of components and make the scaling to larger rotor diameters possible, and therefore improve the cost effectiveness of modern wind turbines. Also the success of future rotor designs will heavily depend for their operation on new developments in active control technologies.
I. Houtzager
PLC Based Test Platform for Wind Turbine Gearbox
Wind turbine gearbox is one of the most important and most expensive components of wind turbine. Once installed, it is difficult to repair. Therefore, it needs effective experiments during its design and production to meet the strict quality requirements. The test platform adopts Closure Design, which enables it to experiment two gearbox products at the same time. And thanks to
Zou Xinyu
Effect of Precipitation on Wind Turbine Performance.
The effects of precipitation on wind turbine power output was analyzed. The tests were conducted on the two bladed Mod-0 horizontal axis wind turbine with three different rotor configurations. Experimental data from these tests are presented which clearly...
R. D. Corrigan R. D. Demiglio
Statistical variation of wind turbine fatigue loads.
The objective of this investigations is to quantify the statistical variation associated with fatigue loads for wind turbines. Based on aeroelastic calculations for a 1.5 MW stall regulated wind turbine, the variation is quantified, and parameters of impo...
K. Thomsen
Vertical axis wind turbine airfoil
A vertical axis wind turbine airfoil is described. The wind turbine airfoil can include a leading edge, a trailing edge, an upper curved surface, a lower curved surface, and a centerline running between the upper surface and the lower surface and from the leading edge to the trailing edge. The airfoil can be configured so that the distance between the centerline and the upper surface is the same as the distance between the centerline and the lower surface at all points along the length of the airfoil. A plurality of such airfoils can be included in a vertical axis wind turbine. These airfoils can be vertically disposed and can rotate about a vertical axis.
Krivcov, Vladimir; Krivospitski, Vladimir; Maksimov, Vasili; Halstead, Richard; Grahov, Jurij Vasiljevich
Wind turbine emulator using wind turbine model based on blade element momentum theory
This paper presents the wind turbine emulator using the wind turbine model based on blade element momentum theory. The lift coefficient cl and drag coefficient cd of designed blade shape are calculated with the fluid analysis. Therefore the proposed wind turbine emulator can emulate the new designed windmill without manufacturing. Also the wind turbine model considers the mechanical model and
K. Ohyama; T. Nakashima
Large band simulation of the wind speed for real time wind turbine simulators
In this paper, the authors propose two modeling procedures for wind speed simulation. These procedures could be implemented on the structure of a wind turbine simulator during studies concerning stand-alone or hybrid wind systems. The evolution of a horizontal wind speed has been synthesized taking into account two components. The medium- and long-term component is described by a power spectrum
Cristian Nichita; Dragos Luca; Brayima Dakyo; Emil Ceanga
The Lebost Wind Turbine experimental program
The Lebost Wind Turbine is unique in two respects: it consists of a vertical axis turbine which is encased in a perforated hemispherical shroud which acts to focus or concentrate ambient wind energy onto the turbine blades; and the turbine's shaft is directly coupled to a water twister\\/heat brake assembly which heats water via direct mechanical agitation; in other words,
G. Miller; M. Hoffert; B. Rugg; D. Corren
The application of pulsed thermography in the inspection of wind turbine blades
Wind power is a very promising source of environmentally safe, renewable, and the fast-growing energy source over the past several years. The blades of a wind turbine are considered to be an important component in wind turbine generator. Currently, bigger and more powerful wind blades are being built to increase the swept area of the turbine and extract more energy
Ning Tao; Zhi Zeng; Lichun Feng; Xiaoli Li; Yeshu Li; Cunlin Zhang
Placement of wind turbines using genetic algorithms
A genetic algorithm approach is employed to obtain optimal placement of wind turbines for maximum production capacity while limiting the number of turbines installed and the acreage of land occupied by each wind farm. Specifically, three cases are consideredŚ(a) unidirectional uniform wind, (b) uniform wind with variable direction, and (c) non-uniform wind with variable direction. In Case (a), 600 individuals
S. A. Grady; M. Y. Hussaini; M. M. Abdullah
Dynamics and Stability of Wind Turbine Generators
This paper describes the dynamic and stability properties of wind turbine generators connected to power systems. Both synchronous and induction generators are considered. A comparison is made between wind turbines, steam, and hydro units. The unusual phenomena associated with wind turbines are emphasized. The general control requirements are discussed, as well as various schemes for torsional damping such as speed
E. N. Hinrichsen; P. J. Nolan
Suggestions for improving wind turbines power curves
The question is usually not whether a wind turbine can be designed to optimise the power production at the site, but rather whether an existing wind turbines with a certain rotor can be modified in order to improve the power production. In this paper the various methods for improving the wind turbines power output were investigated experimentally and theoretically. The
Full-scale modal wind turbine tests: comparing shaker excitation with wind excitation
\\u000a The test facilities at the National Wind Technology Center (NWTC) of the National Renewable Energy Laboratory (NREL) include\\u000a a three-bladed Controls Advanced Research Turbine (CART3). The CART3 is used to test new control schemes and equipment for\\u000a reducing loads on wind turbine components. As wind turbines become lighter and more flexible to reduce costs, novel control\\u000a mechanisms are necessary to
Richard Osgood; Gunjit Bir; Heena Mutha; Bart Peeters; Marcin Luczak; Gert Sablon
Economics of Small Wind Turbines
This presentation from the Advanced Technology Environmental and Energy Center (ATEEC) includes instructional materials related to small wind turbines as well as lab activities. The overall learning objective is for students to understand the value of economic incentives with regard to residential wind systems. Users must download this resource for viewing, which requires a free log-in. There is no cost to download the item.
Wind turbine testing. Final report
Los Alamos National Laboratory (LANL) is investigating concepts for removing heat from nuclear material storage units. One method which has been suggested is the use of wind turbine ventilators on the roofs of the units. An advantage of these devices is that it would require no power to operate them, and in this sense the system would be fail safe. The internal heat in the storage units would naturally cause air to rise through the ventilators and the usually prevailing winds which average about 5 mph would combine with the buoyancy to exhaust the air from the units. However, it was not known whether these type of ventilators can deliver a sufficient air flow through the High Efficiency Particulate Air (HEPA) filters which must be an integral part of the ventilation system in a nuclear storage facility. Therefore, this study was undertaken to answer that question. In this report we will discuss the experiments which were run on two wind turbine ventilators, one with a one foot diameter inlet duct and one with a two foot diameter inlet duct. The wind turbines were supplied by LANL and tested in the New Mexico State University/LANL wind binnel housed in the Mechanical Engineering Department on the Las Cruces Campus of NMSU. The experiments were run at a nominal wind speed of 5 mph, with and without heating below the ventilator inlet and with and without resistance elements at the ventilator inlet.
Smith, P.R.
Preview Control for Wind Turbines
The success of wind power as a renewable energy source depends on its cost of energy. Wind turbine control has attracted much attention in the controls community due to its potential impact on the cost of wind power. However, novel methods in the literature have not transitioned well to industry. This is because the potential cost benefits of these methods are not well understood. There is a need for basic research to address this issue. This thesis is one step toward transitioning of advanced control methods in literature to the industry. Particularly, we aim to understand the limits of performance. The potential performance improvements of the advanced methods should be large enough to justify their cost and complexity. We investigate the optimal trade-offs between multiple turbine performance goals. We also explore the use of a novel wind preview sensor in closed-loop control laws. The impact of this novel sensor on the optimal turbine performance is investigated. The specific contributions of this thesis can be grouped in three categories. First, we present a preliminary, nonlinear optimization based controller design and analysis framework. This framework can simplify the design of the advanced multivariable controllers for nonlinear systems. It can also be used to investigate the optimal design trade-offs between nonlinear performance constraints and objectives. Second, engineering insight is provided into turbine design trade-offs. Third, we provide mathematical tools that quantify the limits of turbine performance in presence of preview wind measurements. Optimization tools that can analyze the trade-off between preview time and operating condition dependent turbine performance objectives are presented. In low wind speeds, our results show that simultaneous power capture improvements and structural load reductions can be obtained. In high wind speeds, a short amount of preview wind information can be used to overcome the fundamental performance limitations imposed by actuator rate constraints. We provide analytical formulas that quantify these preview time requirements and performance limitations. A convex optimization framework is also presented for the analysis of extreme operating conditions that are defined by deterministic wind disturbance trajectories.
Ozdemir, Ahmet Arda
Wind Turbine Siting: Wildlife Concerns
The Advanced Technology Environmental and Energy Center (ATEEC) provides this document on wildlife concerns in relation to the siting of wind turbines. The material includes individual student activities and a list of web resources intended to help teachers. Users must download this resource for viewing, which requires a free log-in. There is no cost to download the item.
Everhart, Roger; Lawton, Wendy
Wind farm control: Addressing the aerodynamic interaction among wind turbines
Wind farms help reduce the average wind cost of energy due to many economies of scale compared to individual turbines located far from each other. However, these groupings introduce the problem of aerodynamic interaction among turbines, which can decrease the total energy converted to electricity compared to the same number of isolated turbines operating under the same wind inflow conditions.
Kathryn E. Johnson; Naveen Thomas
The Selection of a Suitable Maintenance Strategy for Wind Turbines
Common maintenance strategies applied to wind turbines include 'Time-Based' which involves carrying out maintenance tasks at predetermined regular-intervals and 'Failure- Based' which entails using a wind turbine until it fails. However, the consequence of failure of critical components limits the adequacy of these strategies to support the current commercial drivers of the wind industry. Reliability-Centred Maintenance (RCM) is a technique
Jesse A. Andrawus; Mohammed Kishk; Allan Adam
3 MW class offshore wind turbine development
This paper introduces the design and development of a 3MW class offshore wind turbine (WinDS3000). The design has been carried out by considering high reliability, availability, maintainability and serviceability (RAMS) for the wind class TC Ia. An integrated drive train design, which has an innovative three stage gearbox, has been introduced to minimize nacelle weight of the wind turbine and
Jiwoong Park; Jeongil Kim; Youngho Shin; Jeonghoon Lee
Innovatory designs for ducted wind turbines
Designs for conventional ducted wind turbines usually include a large inlet for more absorption of the airflow. However, the most efficient solution should be increasing the speed of wind. In this paper, a bucket-shape ducted wind turbine is proposed and studies show that a sucking effect can be produced according to the Bernoulli's principle, and this significantly increases the wind
Ssu-Yuan Hua; Jung-Ho Cheng
Comparison of field and wind tunnel Darrieus wind turbine data
A 2-m-dia Darrieus Vertical Axis Wind Turbine with NACA-0012 blades was extensively tested in the Vought Corporation Low Speed Wind Tunnel. This same turbine was installed in the field at the Sandia National Laboratories Wind Turbine Test Site and operated to determine if field data corresponded to data obtained in the wind tunnel. It is believed that the accuracy of the wind tunnel test data was verified and thus the credibility of that data base was further established.
Sheldahl, R.E.
Optimization of wind turbine vane manufacture based on queuing theory
Wind turbine vane is the key components of wind power generators effectively capture the wind. RTM is a manufacture technology of advanced composite materials, low cost, medium batch blade. Some random factors often lead to the production schedule can not be predetermined program normally. It can help reduce production costs that with the start-up costs were study of production scheduling
Qing-hui Dai; Sha Li
Wind Turbine Drivetrain Test Facility Data Acquisition System.
The Wind Turbine Drivetrain Test Facility (WTDTF) is a stateof-the-art industrial facility used for testing wind turbine drivetrains and generators. Large power output wind turbines are primarily installed for off-shore wind power generation. The facility...
J. B. McIntosh
Aerodynamics of Horizontal Axis Wind Turbines
\\u000a This chapter reviews the aerodynamic characteristics of horizontal axis wind turbines (HAWTs). While the aerodynamics of wind\\u000a turbine are relatively complicated in detail, the fundamental operational principle of a HAWT is that the action of the blowing\\u000a wind produces aerodynamic forces on the turbine blades to rotate them, thereby capturing the kinetic energy contained in the\\u000a wind and converting this
J. Gordon Leishman
Nonlinear control with wind estimation of a DFIG variable speed wind turbine for power capture optimization
A cascaded nonlinear controller is designed for a variable speed wind turbine equipped with a Doubly Fed Induction Generator (DFIG). The main objective of the controller is wind energy capture optimization while avoiding strong transients in the turbine components and specially in the drive train. The inner loop controller ensures an efficient tracking of both generator torque and stator flux,
B. Boukhezzar; H. Siguerdidjane
Fatigue loads on a pitch regulated wind turbine operating in a coastal wind turbine array.
The objective of this analysis is to improve the foundations for designing wind turbines in wind turbine arrays and wind farms. The analysis is carried out using load measurements on a Vestas/DWT Windane 34 turbine operating in the Kappel wind farm in the...
K. Thomsen H. Bindner T. Friis Pedersen
A Dynamic Wind Turbine Simulator of the Wind Turbine Generator System
To study dynamic performances of wind turbine generator system (WTGS), and to determine the control structures in laboratory. The dynamic torque generated by wind turbine (WT) must be simulated. In there paper, a dynamic wind turbine emulator (WTE) is designed, which consider wind shear and tower shadow effect, and a dynamic torque compensation scheme is also developed to compensate the
Lei Lu; Zhen Xie; Xing Zhang; Shuying Yang; Renxian Cao
Wind turbines are complex, nonlinear, dynamic systems forced by gravity, stochastic wind disturbances, and gravitational, centrifugal, and gyroscopic loads. The aerodynamic behavior of wind turbines is nonlinear, unsteady, and complex. Turbine rotors are subjected to a complicated three-dimensional turbulent wind inflow field that drives fatigue loading. Wind turbine modeling is also complex and challenging. Accurate models must contain many degrees of freedom (DOF) to capture the most important dynamic effects. The rotation of the rotor adds complexity to the dynamics modeling. Designs of control algorithms for wind turbines must account for these complexities. Algorithms must capture the most important turbine dynamics without being too complex and unwieldy. Off-the-shelf commercial soft ware is seldom adequate for wind turbine dynamics modeling. Instead, specialized dynamic simulation codes are usually required to model all the important nonlinear effects. As illustrated in Figure 14-1, a wind turbine control system consists of sensors, actuators and a system that ties these elements together. A hardware or software system processes input signals from the sensors and generates output signals for actuators. The main goal of the controller is to modify the operating states of the turbine to maintain safe turbine operation, maximize power, mitigate damaging fatigue loads, and detect fault conditions. A supervisory control system starts and stops the machine, yaws the turbine when there is a significant yaw misalignment, detects fault conditions, and performs emergency shut-downs. Other parts of the controller are intended to maximize power and reduce loads during normal turbine operation.
Wright, A. D.
Modern control design for flexible wind turbines
Control can improve energy capture and reduce dynamic loads in wind turbines. In the 1970s and 1980s wind turbines used classical control designs to regulate power and speed. The methods used, however, were not always successful. These systems often had bandwidths large enough to destabilize low-damped flexible modes leading to high dynamic load fatigue failures. Modern turbines are larger, mounted
Alan Duane Wright
A variable speed wind turbine power control
To optimize the power in a wind turbine, the speed of the turbine should be able to vary with the wind speed. A simple control scheme is proposed that will allow an induction motor to run a turbine at its maximum power coefficient. The control uses a standard V\\/Hz converter and controls the frequency to achieve the desired power at
Andrew Miller; Edward Muljadi; Donald S. Zinger
Wind turbine reliability : a database and analysis approach.
The US wind Industry has experienced remarkable growth since the turn of the century. At the same time, the physical size and electrical generation capabilities of wind turbines has also experienced remarkable growth. As the market continues to expand, and as wind generation continues to gain a significant share of the generation portfolio, the reliability of wind turbine technology becomes increasingly important. This report addresses how operations and maintenance costs are related to unreliability - that is the failures experienced by systems and components. Reliability tools are demonstrated, data needed to understand and catalog failure events is described, and practical wind turbine reliability models are illustrated, including preliminary results. This report also presents a continuing process of how to proceed with controlling industry requirements, needs, and expectations related to Reliability, Availability, Maintainability, and Safety. A simply stated goal of this process is to better understand and to improve the operable reliability of wind turbine installations.
Linsday, James (ARES Corporation); Briand, Daniel; Hill, Roger Ray; Stinebaugh, Jennifer A.; Benjamin, Allan S. (ARES Corporation)
Studies on the Variable Speed Wind Turbine Control System Based on PSCAD\\/EMTDC
A variable speed wind turbine (VSWT) based on Doubly Fed Induction Generator (DFIG) has some advantages and better integration characteristics comparing with fixed speed wind turbine. On the basis of existing models of main components of wind turbine in the model library of PSCAD\\/EMTDC, the control system of VSWT is established in this paper. Furthermore, taking a kind of prevailing
Feng Shuang-lei; Zhao Hai-xiang; Wang Wei-sheng
Investigation of fatigue life for a medium scale composite wind turbine blade
In order to satisfy fatigue requirements in designing a cost effective wind turbine, the wind turbine blade, which is an expensive key component of the wind turbine system, must achieve very long operating life of 20¢30 years. In this study, the fatigue life of a medium scale (750kW) horizontal axis wind turbine system (HAWIS), which has been developed by the
Changduk Kong; Taekhyun Kim; Dongju Han; Yoshihiko Sugiyama
Review of wind turbine control
The literature on the design of control sysems for medium- and large-scale wind turbine generators is reviewed. The vast majority of relevant literature is concerned with the control of horizontal-axis machines. Emphasis is given to public-utility service machines with power outputs in the range hundreds to thousands of kilowatts. This work was prompted by the need to determine specific objectives
S. A. DE LA SALLE; D. REARDON; W. E. LEITHEAD; M. J. GRlMBLE
WindFloat: A floating foundation for offshore wind turbines
This manuscript summarizes the feasibility study conducted for the WindFloat technology. The WindFloat is a three-legged floating foundation for multimegawatt offshore wind turbines. It is designed to accommodate a wind turbine, 5 MW or larger, on one of the columns of the hull with minimal modifications to the nacelle and rotor. Potential redesign of the tower and of the turbine
Dominique Roddier; Christian Cermelli; Alexia Aubault; Alla Weinstein
Reduced model of DFIGs wind farms using aggregation of wind turbines and equivalent wind
In this paper, a new reduced model of wind farms with doubly-fed induction generators wind turbines is proposed for representing all the wind turbines of a wind farm by one single equivalent wind turbine. The simulation results demonstrate the effectiveness of the proposed reduced model to represent the collective response of a wind farm in the point of common coupling
L. M. Fernandez; C. A. Garcia; J. R. Saenz; F. Jurado
Frequency control and wind turbine technologies
Increasing levels of wind generation has resulted in an urgent need for the assessment of their impact on frequency control of power systems. Whereas increased system inertia is intrinsically linked to the addition of synchronous generation to power systems, due to differing electromechanical characteristics, this inherent link is not present in wind turbine generators. Regardless of wind turbine technology, the
Gillian Lalor; Alan Mullane; Mark O'Malley
Wind turbine performance under icing conditions
The effects of rime ice on horizontal axis wind turbine performance were estimated. For typical supercooled fog conditions found in cold northern regions, four rime ice accretions on the S809 wind turbine airfoil were predicted using the NASA LEWICE code. The resulting airfoil\\/ice profile combinations were wind tunnel tested to obtain the lift, drag, and pitching moment characteristics over the
W. J. Jasinski; S. C. Noe; M. S. Selig; M. B. Bragg
Dynamic models of wind farms with fixed speed wind turbines
The increasing wind power penetration on power systems requires the development of adequate wind farms models for representing the dynamic behaviour of wind farms on power systems. The behaviour of a wind farm can be represented by a detailed model including the modelling of all wind turbines and the wind farm electrical network. But this detailed model presents a high
Luis M. Fernßndez; Josķ Ram¾n Saenz; Francisco Jurado
Horizontal Axis Wind Turbine Blade Aerodynamics in Experiments and Modeling
Turbine aerodynamics remains a challenging and crucial research area for wind energy. Blade aerodynamic forces responsible for power production must be augmented to maximize energy capture. At the same time, adverse aerodynamic loads that fatigue turbine components need to be mitigated to extend machine service life. Successful resolution of these conflicting demands and continued cost of energy reduction require accurate
Scott J. Schreck; Michael C. Robinson
Turbine efficiency remains a critical component of the overall economic justification for a potential wind farm. There is therefore a requirement for prediction methodologies that are capable of addressing the in-situ performance of multiple turbine installations within a specific local environment and operating in a range of conditions. The work presented here is the first stage in a programme of
David Hartwanger; Andrej Horvat
Impedance-based structural health monitoring of wind turbine blades
Wind power is a fast-growing source of non-polluting, renewable energy with vast potential. However, current wind turbine technology must be improved before the potential of wind power can be fully realized. Wind turbine blades are one of the key components in improving this technology. Blade failure is very costly because it can damage other blades, the wind turbine itself, and possibly other wind turbines. A successful damage detection system incorporated into wind turbines could extend blade life and allow for less conservative designs. A damage detection method which has shown promise on a wide variety of structures is impedance-based structural health monitoring. The technique utilizes small piezoceramic (PZT) patches attached to a structure as self-sensing actuators to both excite the structure with high-frequency excitations, and monitor any changes in structural mechanical impedance. By monitoring the electrical impedance of the PZT, assessments can be made about the integrity of the mechanical structure. Recently, advances in hardware systems with onboard computing, including actuation and sensing, computational algorithms, and wireless telemetry, have improved the accessibility of the impedance method for in-field measurements. This paper investigates the feasibility of implementing such an onboard system inside of turbine blades as an in-field method of damage detection. Viability of onboard detection is accomplished by running a series of tests to verify the capability of the method on an actual wind turbine blade section from an experimental carbon/glass/balsa composite blade developed at Sandia National Laboratories.
Pitchford, Corey; Grisso, Benjamin L.; Inman, Daniel J.
Comparison of variable geometry vertical axis wind turbines with horizontal axis wind turbines.
This study is a technical and economic comparison of variable geometry vertical axis wind turbines (VGVAWTs) with horizontal axis wind turbines (HAWTs). Major technical advantages claimed for VAWTs are that they are omnidirectional, i.e. they do not need ...
R. A. W. Shock
LES of wind turbine wakes: Evaluation of turbine parameterizations
Large-eddy simulation (LES), coupled with a wind-turbine model, is used to investigate the characteristics of wind turbine wakes in turbulent boundary layers under different thermal stratification conditions. The subgrid-scale (SGS) stress and SGS heat flux are parameterized using scale-dependent Lagrangian dynamic models (Stoll and Porte-Agel, 2006). The turbine-induced lift and drag forces are parameterized using two models: an actuator disk
Fernando Porte-Agel; Yu-Ting Wu; Leonardo Chamorro
The use of wind power to generate electricity continues to grow, especially given commitments by various countries throughout the world to ensure that a significant percentage of energy comes from renewable sources. In order to meet such objectives, increasingly larger turbines with higher capacity are being developed. The engineering aspects of larger turbine development tend to focus on design and materials for blades and towers. However, foundations are also a critical component of large wind turbines and represent a significant cost of wind energy projects. Ongoing wind research at BNL is examining two areas: (a) structural response analysis of wind turbine-tower-foundation systems and (b) materials engineering of foundations. This work is investigating the dynamic interactions in wind turbine systems, which in turn assists the wind industry in achieving improved reliability and more cost efficient foundation designs. The results reported herein cover initial studies of concrete mix designs for large wind turbine foundations and how these may be tailored to reduce cost and incorporate sustainability and life cycle concepts. The approach taken was to investigate material substitutions so that the environmental, energy and CO{sub 2}-impact of concrete could be reduced. The use of high volumes of ''waste'' materials in concrete was examined. These materials included fly ash, blast furnace slag and recycled concrete aggregate. In addition, the use of steel fiber reinforcement as a means to improve mechanical properties and potentially reduce the amount of bar reinforcement in concrete foundations was studied. Four basic mixes were considered. These were: (1) conventional mix with no material substitutions, (2) 50% replacement of cement with fly ash, (3) 50% replacement of cement with blast furnace slag and (4) 25% replacement of cement with fly ash and 25% replacement with blast furnace slag. Variations on these mixes included the addition of 1% by volume steel fibers. The use of recycled concrete aggregate in the conventional and 50% slag mixes was also studied. Properties investigated included compressive and tensile strengths, elastic modulus, coefficient of permeability, thermal conductivity and durability in seawater and sulfate solutions. It was determined that the mixes containing 50% slag gave the best overall performance. Slag was particularly beneficial for concrete that used recycled aggregate and could reduce strength losses. Initial durability results indicated that corrosion of fibers in the different concrete mixes when exposed to seawater was minimal. Future research needs to include more detailed studies of mix design and properties of concrete for wind turbine foundations. Emphasis on slag-modified mixes with natural and recycled concrete aggregate is recommended. The proportion of slag that can be incorporated in the concrete needs to be optimized, as does the grading of recycled aggregate. The potential for using silica fume in conjunction with slag is worth exploring as this may further enhance strength and durability. Longer-term durability studies are necessary and other pertinent properties of concrete that require investigation include damping characteristics, pullout strength, fatigue strength and risk of thermal cracking. The properties of sustainable concrete mixes need to be integrated with studies on the structural behavior of wind turbine foundations in order to determine the optimal mix design and to examine means of reducing conservatism and cost of foundations.
Modeling Smart Structure of Wind Turbine Blade
With the increasing size of wind turbine blades, the need for more sophisticated load control techniques has induced the interest for aerodynamic control systems with build-in intelligence on the blades. The paper aims to provide a way for modeling the adaptive wind turbine blades and analyze its ability for vibration suppress. It consists of the modeling of the adaptive wind turbine blades with the wire of piezoelectric material embedded in blade matrix, and smart sandwich structure of wind turbine blade. By using this model, an active vibration method which effectively suppresses the vibrations of the smart blade is designed.
Qiao, Yin-hu; Han, Jiang; Zhang, Chun-yan; Chen, Jie-ping
Wind Turbine Generator System Safety and Function Test Report for the Ventera VT10 Wind Turbine
This report summarizes the results of a safety and function test that NREL conducted on the Ventera VT10 wind turbine. This test was conducted in accordance with the International Electrotechnical Commissions' (IEC) standard, Wind Turbine Generator System Part 2: Design requirements for small wind turbines, IEC 61400-2 Ed.2.0, 2006-03.
Smith, J.; Huskey, A.; Jager, D.; Hur, J.
Wind Turbine Generator System Safety and Function Test Report for the Entegrity EW50 Wind Turbine
This report summarizes the results of a safety and function test that NREL conducted on the Entegrity EW50 wind turbine. This test was conducted in accordance with the International Electrotechnical Commissions' (IEC) standard, Wind Turbine Generator System Part 2: Design requirements for small wind turbines, IEC 61400-2 Ed.2.0, 2006-03.
Wind turbine blade tip comparison using CFD
The effect of wind turbine blade tip geometry is numerically analysed using Computational Fluid Dynamics (CFD). Three different rotating blade tips are compared for attached flow conditions and the flow physics around the geometries are analysed. To this end, the pressure coefficient (Cp) is defined based on the stagnation pressure rather than on the inflow dynamic pressure. The tip geometry locally modifies the angles of attack (AOA) and the inflow dynamic pressure at each of the studied sections. However not all 3D effects could be reduced to a change of these two variables. An increase in loadings (particularly the normal force) towards the tip seem to be associated to a spanwise flow component present for the swept-back analysed tip. Integrated loads are ranked to asses wind turbine tip overall performance. It results from the comparison that a better tip shape that produced better torque to thrust ratios in both forces and moments is a geometry that has the end tip at the pitch axis. The work here presented shows that CFD may prove to be useful to complement 2D based methods on the design of new wind turbine blade tips.
Ferrer, E.; Munduate, X.
Designing Drive Trains for the Next Generation of Wind Turbines (FloDesign Wind Turbine Corporation)
Today's wind turbines have nearly reached their maximum possible efficiency and are limited to sites with a narrow profile of wind patterns. The patent-pending Mixer Ejector Wind Turbine (MEWT) concept proposed by FloDesign promises to outperform existing wind turbines by a factor of three or more in a much wider range of wind resources. Olin CollegeÆs FloDesign SCOPE team was
Mateen Abdul; Kelcy Adamec; Gavin Boggs; Matthew Crawford; Kevin Sihlanick; Russell Torres
Coated superalloy gas turbine components
A gas turbine component is described consisting of a non-symmetrical body made of material selected from the group consisting of nickel-base superalloy, cobalt-base superalloy and iron-base superalloy and an alloy coating metallurgically bonded by an interdiffusion zone and providing the outer surface for the coated body. The composition of the coating consists essentially of (in weight percent) about 43% chromium;
Dynamic Wind Loads and Vortex Structures in the Wake of a Wind Turbine
We report an experimental study to characterize the dynamic wind loads and evolution of wake vortex flow structures downstream of a horizontal axis wind turbine (HAWT). The experiments were conducted in a wind tunnel with a wind turbine model placed in a boundary layer flow developed over rough and smooth surfaces in order to study the effects of roughness and the resulting velocity and turbulence fields on the wake characteristics and fatigue loads acting on the wind turbine. In addition to measuring dynamic wind loads (both aerodynamic forces and moments) acting on the wind turbine model using a six-component load cell, a high-resolution Particle Image Velocimetry (PIV) system was used to make phase-locked flow field measurements to quantify the time-evolution of the wake vortex and turbulence flow structures shedding from wind turbine blades. The detailed flow field measurements were correlated with the wind load measurements to elucidate the underlying physics associated with turbine power generation and fatigue loads acting on wind turbines.
Hu, Hui; Yang, Zifeng; Sarkar, Partha
Wind Turbine Generator System Power Performance Test Report for the ARE442 Wind Turbine
This report summarizes the results of a power performance test that NREL conducted on the ARE 442 wind turbine. This test was conducted in accordance with the International Electrotechnical Commission's (IEC) standard, Wind Turbine Generator Systems Part 12: Power Performance Measurements of Electricity Producing Wind Turbines, IEC 61400-12-1 Ed.1.0, 2005-12. However, because the ARE 442 is a small turbine as defined by IEC, NREL also followed Annex H that applies to small wind turbines. In these summary results, wind speed is normalized to sea-level air density.
van Dam, J.; Jager, D.
Mixer-Ejector Wind Turbine: Breakthrough High Efficiency Shrouded Wind Turbine
Broad Funding Opportunity Announcement Project: FloDesign Wind TurbineÆs innovative wind turbine, inspired by the design of jet engines, could deliver 300% more power than existing wind turbines of the same rotor diameter by extracting more energy over a larger area. FloDesign Wind TurbineÆs unique shrouded design expands the wind capture area, and the mixing vortex downstream allows more energy to flow through the rotor without stalling the turbine. The unique rotor and shrouded design also provide significant opportunity for mass production and simplified assembly, enabling mid-scale turbines (approximately 100 kW) to produce power at a cost that is comparable to larger-scale conventional turbines.
Towards Quantification of Condition Monitoring Benefit for Wind Turbine Generators
Condition monitoring systems are increasingly installed in wind turbine generators with the goal of providing component-specific information to the wind farm operator and hence increase equipment availability through maintenance and operating actions based on this information. In some cases, however, the economic benefits of such systems are unclear. A quantitative measure of these benefits may therefore be of value to
David McMillan; Graham Ault
Microprocessor control of a wind turbine generator
A microprocessor based system was used to control the unattended operation of a wind turbine generator. The turbine and its microcomputer system are fully described with special emphasis on the wide variety of tasks performed by the microprocessor for the safe and efficient operation of the turbine. The flexibility, cost and reliability of the microprocessor were major factors in its selection.
Gnecco, A. J.; Whitehead, G. T.
This paper describes a microprocessor based system used to control the unattended operation of a wind turbine generator. The turbine and its microcomputer system are fully described with special emphasis on the wide variety of tasks performed by the microprocessor for the safe and efficient operation of the turbine. The flexibility, cost and reliability of the microprocessor were major factors in its selection.
Wind Turbine Certification and Type Certification IEC WT 01: IEC System for Conformity Testing and Certification of Wind Turbines, 2001-04
Mike Woebbeking; Axel Andreõ; Axel Dombrowski; Germanischer Lloyd
Superconductivity for Large Scale Wind Turbines
A conceptual design has been completed for a 10MW superconducting direct drive wind turbine generator employing low temperature superconductors for the field winding. Key technology building blocks from the GE Wind and GE Healthcare businesses have been transferred across to the design of this concept machine. Wherever possible, conventional technology and production techniques have been used in order to support the case for commercialization of such a machine. Appendices A and B provide further details of the layout of the machine and the complete specification table for the concept design. Phase 1 of the program has allowed us to understand the trade-offs between the various sub-systems of such a generator and its integration with a wind turbine. A Failure Modes and Effects Analysis (FMEA) and a Technology Readiness Level (TRL) analysis have been completed resulting in the identification of high risk components within the design. The design has been analyzed from a commercial and economic point of view and Cost of Energy (COE) calculations have been carried out with the potential to reduce COE by up to 18% when compared with a permanent magnet direct drive 5MW baseline machine, resulting in a potential COE of 0.075 $/kWh. Finally, a top-level commercialization plan has been proposed to enable this technology to be transitioned to full volume production. The main body of this report will present the design processes employed and the main findings and conclusions.
R. Fair; W. Stautner; M. Douglass; R. Rajput-Ghoshal; M. Moscinski; P. Riley; D. Wagner; J. Kim; S. Hou; F. Lopez; K. Haran; J. Bray; T. Laskaris; J. Rochford; R. Duckworth
Sensorless active yaw control for wind turbines
An active yaw control scheme for a horizontal axis wind turbine is proposed. The control strategy is based on measurement of the generated output power, without any wind intensity and\\/or wind direction sensors. Special attention is given to some control parameters to make the yaw driver less sensitive to wind turbulence. Results obtained in the laboratory implementation are presented and
Felix A. Farret; L. L. Pfitscher; Daniel P. Bernardon
Condition monitoring and fault diagnostics of wind turbines
Condition monitoring and fault diagnostics is important for wind turbines to ensure safety and reliability. However, the application in wind turbine is still in initial stage. This paper analyses the frequent faults in wind turbines and determines the sensor configuration of a wind turbine. Architecture of condition monitoring and fault diagnostics system is built to monitor a wind farm. Methodology
Wenxiu Lu; Fulei Chu
Laboratory-scale experiments on wind turbine nacelle movement estimation
The effect of nacelle motion should be considered when calculating the wind speed relative to the wind turbine structure, which is essential in wind turbine control and performance testing. A Kalman filter approach is applied to estimate the nacelle motion of a wind turbine. Information from several accelerometers and strain gauges which are installed on the wind turbine tower is
Yoonsu Nam; Tai Jun Yoon
This paper describes the methodology to obtain the power curve of Small Wind Turbine Generators (SWTG) in field and in the laboratory. A system includes a wind turbine, data logger and transducers with capacity of measuring the instantaneous power of the wind turbine for different wind speed. Three wind turbines was tested in laboratory with the blades using fluid flow
Pontifical Catholic; Jorge Antonio
This paper describes computational aeroacoustic methods that are being applied to predict the noise radiated by wind turbines. Since the wind turbine noise problem is very challenging, only some of the important noise sources and mechanisms are being considered. These are airfoil self-noise, the effects of blade rotation, and the propagation of sound over large distances. Two aspects of airfoil
Philip J. Morris; Lyle N. Long; Kenneth S. Brentner
Dynamic stall on wind turbine blades
Dynamic loads must be predicted accurately in order to estimate the fatigue life of wind turbines operating in turbulent environments. Dynamic stall contributes to increased dynamic loads during normal operation of all types of horizontal-axis wind turbine (HAWTs). This report illustrates how dynamic stall varies throughout the blade span of a 10 m HAWT during yawed and unyawed operating conditions.
C. P. Butterfield; D. Simms; G. Scott; A. C. Hansen
An integrated modeling method for wind turbines
To study the interaction of the electrical, mechanical, and aerodynamic aspects of a wind turbine, a detailed model that considers all these aspects must be used. A drawback of many studies in the area of wind turbine simulation is that either a very simple mechanical model is used with a detailed electrical model, or vice versa. Hence the interactions between
Roohollah Fadaeinedjad
Wind turbine value analysis for electric utilities
A methodology for the analysis of the value of large-scale wind turbines to electric utilities, and its application to utility, socioeconomic and meteorological data in two case studies is described. The value analysis was carried out for the year of reference 1985 and included different levels of wind turbine penetration. Results of the value analysis are given. The utility planning
W. Dub
Multimode control system for wind turbines
A multi-mode electronic wind turbine control system establishes a reference blade angle for a two-bladed, horizontal axis, variable pitch wind turbine rotor, the blade angle being regulated by a hydraulic pitch change mechanism. The rotor, via appropriate shafts and a gearbox, is coupled to a synchronous generator to produce electrical energy which is fed to a power utility grid. The
K. I. Harner; J. M. Kos; J. P. Patrick
Design evolution of large wind turbine generators
During the past five years, the goals of economy and reliability have led to a significant evolution in the basic design--both external and internal--of large wind turbine systems. To show the scope and nature of recent changes in wind turbine designs, development of three types are described: (1) system configuration developments; (2) computer code developments; and (3) blade technology developments.
Spera, D. A.
SUMMARY This paper reports the first findings of an ongoing research programme on wind turbine computational aerodynamics at the University of Glasgow. Several modeling aspects of wind turbine airfoil aerodynamics based on the solution of the Reynolds- averaged Navier-Stokes (RANS) equations are addressed. One of these is the effect of an a priori method for structured grid adaptation aimed at
M. S. Campobasso; A. Zanon; M. Foerster; F. Fraysse; A. Bonfiglioli
Multifunctional nanocomposite coating for wind turbine blades
In this study, multifunctional carbon nanofiber (CNF) paper-based nanocomposite coating was developed for wind turbine blades. The importance of vibration damping in relation to structural stability, dynamic response, position control, and durability of wind turbine blades cannot be underestimated. The vibration damping properties of the nanocomposite blades were significantly improved and the damping ratio of the nanocomposite increased by 300%
Fei Liang; Jihua Gou; Jay Kapat; Haichang Gu; Gangbing Song
Optical Motion Analysis of Wind Turbines.
The study reported in this paper is aimed at discovering the pros and cons of optical motion analysis of large wind turbines. A state of the art optical motion analysis technique was applied for the first time to a wind turbine of 10(m) diameter. Two vide...
G. P. Corten J. C. Sabel
Wind turbine modeling using the bond graph
This paper addresses the problem of bond graph methodology as a graphical approach for modeling wind turbine systems. In this case, we consider the modeling of a wind turbine system with individual pitch control scheme and the interaction with tower motions. Two different bond graph models are presented, one complex and one simplified. Furthermore, the purpose of this paper is
Tore Bakka; Hamid Reza Karimi
Simulation investigation of wind turbine imbalance faults
This paper investigates the use of simulations to study wind turbine imbalance faults. The dynamics of a model wind turbine generator (WTG) are simulated in a combined environment of TurbSim, FAST (Fatigue, Aerodynamics, Structures, Turbulence), and Simulink in three different scenarios, i.e., normal operating conditions, blade imbalance, and aerodynamic asymmetry. The blade imbalance is simulated by scaling the mass density
Xiang Gong; Wei Qiao
Certification testing for small wind turbines
This paper describes the testing procedures for obtaining type certification for a small wind turbine. Southwest Windpower (SWWP) is seeking type certification from Underwriters Laboratory (UL) for the AIR 403 wind turbine. UL is the certification body and the National Renewable Energy Laboratory (NREL) is providing technical assistance including conducting the certification testing. This is the first small turbine to be certified in the US, therefore standards must be interpreted and test procedures developed.
Corbus, D.; Link, H.; Butterfield, S.; Stork, C.; Newcomb, C.
Model 0A wind turbine generator FMEA
The results of Failure Modes and Effects Analysis (FMEA) conducted for the Wind Turbine Generators are presented. The FMEA was performed for the functional modes of each system, subsystem, or component. The single-point failures were eliminated for most of the systems. The blade system was the only exception. The qualitative probability of a blade separating was estimated at level D-remote. Many changes were made to the hardware as a result of this analysis. The most significant change was the addition of the safety system. Operational experience and need to improve machine availability have resulted in subsequent changes to the various systems which are also reflected in this FMEA.
Klein, William E.; Lalli, Vincent R.
Atmospheric and Wake Turbulence Impacts on Wind Turbine Fatigue Loadings
Large-eddy simulations of atmospheric boundary layers under various stability and surface roughness conditions are performed to investigate the turbulence impact on wind turbines. In particular, the aeroelastic responses of the turbines are studied to characterize the fatigue loading of the turbulence present in the boundary layer and in the wake of the turbines. Two utility-scale 5-MW turbines that are separated by seven rotor diameters are placed in a 3 km by 3 km by 1 km domain. They are subjected to atmospheric turbulent boundary layer flow and data is collected on the structural response of the turbine components. The surface roughness was found to increase the fatigue loads while the atmospheric instability had a small influence. Furthermore, the downstream turbines yielded higher fatigue loads indicating that the turbulent wakes generated from the upstream turbines have significant impact.
Lee, S.; Churchfield, M.; Moriarty, P.; Jonkman, J.; Michalakes, J.
Economics of large wind turbine generators
This study demonstrates that established utility system planning methods are applicable to studying wind turbine generators, with minor modifications. A total utility cost approach was used to evaluate the economics of wind turbine generators. The limitations of the busbar energy cost method rule out its use. Three analytic models are studied: the wind plant performance model, the generation system reliability model, and the generation system production cost model. The results of generation, transmission, and distribution studies are interpreted. The results are then integrated to give a single measure of the value of distributed wind turbines. These results demonstrate that the value of distributed wind turbines is dominated by the generation energy and capacity value. The quality and availability of the wind resource far outweighs credits achievable from an optimal electrical location.
Oplinger, J.L.
Streamwise development of the wind turbine boundary layer over a model wind turbine array
The streamwise development of turbulence statistics and mean kinetic energy in a model wind farm consisting of 3 ū 5 wind turbines is studied experimentally in a wind tunnel. The analysis uses planar Particle Image Velocimetry data obtained at the centerline plane of the wind farm, covering the inflow as well as four planes in between five downstream wind turbines. The data analysis is organized by dividing these measurement planes into three regions: the above-rotor, rotor-swept, and below-rotor regions. For each field, flow development is quantified using a properly defined relative difference norm based on an integration over each of the regions. Using this norm, it is found that the mean streamwise velocity approaches a fully developed state most rapidly, whereas the flow development is more gradual for the second-order statistics. The vertical entrainment flux of the mean kinetic energy by the Reynolds shear stress, , is observed to develop at a rate similar to that of the Reynolds shear stress rather than the mean streamwise velocity component. Its development is slowest in the layer nearest to the ground. Analysis of various terms in the mean kinetic energy equation shows that the wind turbine boundary layer has not yet reached fully developed conditions by the fifth turbine but that it is approaching such conditions. By comparing the vertical entrainment flux with the horizontal flux due to the mean flow, it is found that the former increases, whereas the latter decreases, as function of downstream distance, but that the former is already an important contributor in the developing region.
Newman, Jensen; Lebron, Jose; Meneveau, Charles; Castillo, Luciano
With the increasing size of wind turbine blades, the need for more sophisticated load control techniques has induced the interest\\u000a for aerodynamic control systems with build-in intelligence on the blades. The paper aims to provide a way for modeling the\\u000a adaptive wind turbine blades and analyze its ability for vibration suppress. It consists of the modeling of the adaptive wind
Yin-Hu Qiao; Jiang Han; Chun-Yan Zhang; Jie-Ping Chen
Development of the Ris° wind turbine airfoils
This paper presents the wind turbine airfoil development at Ris°. The design method is described together with our target characteristics for wind turbine airfoils. The use of the CFD code Ellipsys2D for prediction of final target characteristics is described together with the VELUX wind tunnel testing setup. Three airfoil families were developed; Ris°-A1, Ris°-P and Ris°-B1. The Ris°-A1 airfoil family
Peter Fuglsang; Christian Bak
Wind Turbine Performance Under Icing Conditions
The effects of rime ice on horizontal axis wind turbine performance were estimated. For typical supercooled fog conditions found in cold northern regions, four rime ice accretions on the S809 wind turbine airfoil were predicted using the NASA LEWICE code. The resulting airfoil\\/ice profile combinations were wind-tunnel tested to obtain the lift, drag, and pitching moment characteristics over the Reynolds
William J. Jasinski; Urbana Shawn; C. Noe
Aerodynamic response analysis of wind turbines
Wind energy has received increasing attention in the same way as energy crisis and environmental deterioration. The aerodynamic\\u000a response of wind turbines is the major problem in wind turbine design. Blade element momentum theory was used to study the\\u000a aerodynamic thrusts of the blades on the tower. Iterative solutions were used to calculate the axial flow induction factor\\u000a for each
Jing Li; Jianyun Chen; Xiaobo Chen
Wind turbine control system modeling capabilities
At the National Renewable Energy Laboratory`s (NREL`s) National Wind Technology Center the authors are continuing to make progress in their ability to model complete wind turbine systems. An ADAMS{reg_sign} model of the NREL variable speed test bed turbine was developed to determine whether wind turbine control systems could be simulated and to investigate other control strategies for this turbine. Model simulations are compared with data from the operating turbine using the current mode of operation. In general, the simulations show good agreement with test data. Having established confidence in their ability to model the physical machine, the authors evaluated two other control methods. The methods studied are a generalized predictive control method and a bias estimation method. Simulation results using these methods are compared to simulation results of the current mode of operation of the turbine.
Pierce, K.; Fingersh, L.J.
Assessment of wind characteristics and wind turbine characteristics in Taiwan
Wind characteristics and wind turbine characteristics in Taiwan have been thoughtfully analyzed based on a long-term measured data source (1961¢1999) of hourly mean wind speed at 25 meteorological stations across Taiwan. A two-stage procedure for estimating wind resource is proposed. The yearly wind speed distribution and wind power density for the entire Taiwan is firstly evaluated to provide annually spatial
Tsang-Jung Chang; Yu-Ting Wu; Hua-Yi Hsu; Chia-Ren Chu; Chun-Min Liao
Preform spar cap for a wind turbine rotor blade
A spar cap for a wind turbine rotor blade. The spar cap may include multiple preform components. The multiple preform components may be planar sheets having a swept shape with a first end and a second end. The multiple preform components may be joined by mating the first end of a first preform component to the second end of a next preform component, forming the spar cap.
Livingston, Jamie T. (Simpsonville, SC); Driver, Howard D. (Greer, SC); van Breugel, Sjef (Enschede, NL); Jenkins, Thomas B. (Cantonment, FL); Bakhuis, Jan Willem (Nijverdal, NL); Billen, Andrew J. (Daarlerveen, NL); Riahi, Amir (Pensacola, FL)
Development of wind turbine towers using fiber reinforced polymers
With an ongoing trend in the wind turbine market, the size of wind turbines has been increasing continuously. Larger wind turbines imply an increase in size, weight, and loads acting on the wind turbine tower. This requires towers to be stronger and stiffer, and consequently leads to bigger tower diameters. Because of their size and weight, transportation and erection require
Nibong Ungkurapinan
Wind turbine reliability :understanding and minimizing wind turbine operation and maintenance costs
Wind turbine system reliability is a critical factor in the success of a wind energy project. Poor reliability directly affects both the project's revenue stream through increased operation and maintenance (O&M) costs and reduced availability to generate power due to turbine downtime. Indirectly, the acceptance of wind-generated power by the financial and developer communities as a viable enterprise is influenced
Walford; Christopher A
Effect of precipitation on wind turbine performance
The effects of precipitation on wind turbine power output was analyzed. The tests were conducted on the two bladed Mod-0 horizontal axis wind turbine with three different rotor configurations. Experimental data from these tests are presented which clearly indicate that the performance of the Mod-0 wind turbine is affected by rain. Light rainfall degraded performance by as much as 20 percent while heavy rainfall degraded performance by as much as 30 percent. Snow mixed with drizzle degraded performance by as much as 36 percent at low windspeeds. Also presented are the results of an analysis to predict the effect of rain on wind turbine performance. This analysis used a blade element/momentum code with modified airfoil characteristics to account for the effect of rain and predicted a loss in performance of 31 percent in high winds with moderate rainfall rates. These predicted results agreed well with experimental data.
Corrigan, R. D.; Demiglio, R. D.
Active load control techniques for wind turbines.
This report provides an overview on the current state of wind turbine control and introduces a number of active techniques that could be potentially used for control of wind turbine blades. The focus is on research regarding active flow control (AFC) as it applies to wind turbine performance and loads. The techniques and concepts described here are often described as 'smart structures' or 'smart rotor control'. This field is rapidly growing and there are numerous concepts currently being investigated around the world; some concepts already are focused on the wind energy industry and others are intended for use in other fields, but have the potential for wind turbine control. An AFC system can be broken into three categories: controls and sensors, actuators and devices, and the flow phenomena. This report focuses on the research involved with the actuators and devices and the generated flow phenomena caused by each device.
van Dam, C.P. (University of California, Davis, CA); Berg, Dale E.; Johnson, Scott J. (University of California, Davis, CA)
A Copula Model of Wind Turbine Performance
The conventional means of assessing the perfor- mance of a wind turbine is through consideration of its power curve which provides the relationship between power output and measured wind speed. In this letter, it is shown how the joint probability distribution of power and wind speed can be learned from data, rather than from examination of the implied function of
Bruce Stephen; Stuart J. Galloway; David McMillan; David C. Hill; David G. Infield
Stochastic wind turbine control in multiblade coordinates
In this paper we consider wind turbine load attenuation through model based control. Asymmetric loads caused by the wind field can be reduced by pitching the blades individually. To this end we investigate the use of stochastic models of the wind which can be included in a model based individual pitch controller design. In this way the variability of the
Sven Creutz Thomsen; Henrik Niemann; Niels Kj°lstad Poulsen
Horizontal axis wind turbine systems: optimization using genetic algorithms
A method for the optimization of a grid-connected wind turbine system is presented. The behaviour of the system components is coupled in a non-linear way, and optimization must take into account technical and economical aspects of the complete system design. The annual electrical energy cost is estimated using a cost model for the wind turbine rotor, nacelle and tower and an energy output model based on the performance envelopes of the power coefficient of the rotor, CP, on the Weibull parameters k and c and on the power law coefficient of the wind profile. In this study the site is defined with these three parameters and the extreme wind speed Vmax. The model parameters vary within a range of possible values. Other elements of the project (foundation, grid connection, financing cost, etc.) are taken into account through coefficients. The optimal values of the parameters are determined using genetic algorithms, which appear to be efficient for such a problem. These optimal values were found to be very different for a Mediterranean site and a northern European site using our numerical model. Optimal wind turbines at the Mediterranean sites considered in this article have an excellent profitability compared with reference northern European wind turbines. Most of the existing wind turbines appear to be well designed for northern European sites but not for Mediterranean sites.
Diveux, T.; Sebastian, P.; Bernard, D.; Puiggali, J. R.; Grandidier, J. Y.
Wake measurements around operating wind turbines
Researchers at Oregon State University have conducted wind measurement programs to describe the wake behind large horizontal axis turbines at Goodnoe Hills, Washington, (MOD-2), and behind the FloWind vertical axis wind turbine near Ellenburg, Washington. Wake measurements were taken using portable kite anemometers as well as fixed place anemometers under several atmospheric stability conditions and turbine operating conditions. Centerline hub height (midrotor) measurements were taken downwind and crosswind from 3-9 diameters. These wake programs are discussed and the velocity deficits measured are compared to the estimated deficits calculated from wake models.
Baker, R.W.; Katen, P.C.; Walker, S.N.
WindPACT Turbine Design Scaling Studies Technical Area 2: Turbine, Rotor and Blade Logistics
Through the National Renewable Energy Laboratory (NREL), the United States Department of Energy (DOE) implemented the Wind Partnership for Advanced Component Technologies (WindPACT) program. This program will explore advanced technologies that may reduce the cost of energy (COE) from wind turbines. The initial step in the WindPACT program is a series of preliminary scaling studies intended to determine the optimum sizes for future turbines, help define sizing limits for certain critical technologies, and explore the potential for advanced technologies to contribute to reduced COE as turbine scales increase. This report documents the results of Technical Area 2-Turbine Rotor and Blade Logistics. For this report, we investigated the transportation, assembly, and crane logistics and costs associated with installation of a range of multi-megawatt-scale wind turbines. We focused on using currently available equipment, assembly techniques, and transportation system capabilities and limitations to hypothetically transport and install 50 wind turbines at a facility in south-central South Dakota.
Smith, K.
Measurements on a wind turbine wake: 3D effects and bluff body vortex shedding
The velocity field in the wake of a two-bladed wind turbine model (diameter 180 mm) has been studied under different conditions using a two-component hot wire. All three velocity components were measured both for the turbine rotor normal to the oncoming flow as well as with the turbine inclined to the freestream direction (the yaw angle was varied from 0░
D. Medici; P. H. Alfredsson
Wind technology development: Large and small turbines
Wind technology has developed rapidly over the last decade with the design and development of advanced systems with improved performance, higher reliability, and lower costs. During the past several years, substantial gains have been made in wind turbine designs, lowering costs to an average of $0.05/kWh while further technology development is expected to allow the cost to drop below $0.04/kWh by 2000. As a result, wind is expected to be one of the least expensive forms of new electric generation in the next century. This paper will present the technology developments for both utility-scale wind turbines and remote, small-village wind turbines that are currently available or in development. Technology innovations are being adapted for remote and stand-alone power applications with smaller wind turbines. Hybrid power systems using smaller 1 to 50 (kW) wind turbines are being developed for non-grid-connected electrical generation applications. These village power systems typically use wind energy, photovoltaics, battery storage, and conventional diesel generators to power remote communities. Smaller turbines are being explored for application as distributed generation sources on utility grids to supply power during periods of peak demand, avoiding costly upgrades in distribution equipment. New turbine designs now account for turbulence-induced loads, unsteady aerodynamic stall effects, and complex fatigue loads, making use of new technology developments such as advanced airfoils. The new airfoils increase the energy capture, improve the operating efficiency, and reduce the sensitivity of the airfoils to operation roughness. Electronic controls are allowing variable rotor speed operation; while aerodynamic control devices, such as ailerons and flaps, are used to modulate power or stop the rotor in high-speed conditions. These technology trends and future turbine configurations are being sponsored and explored by the U.S. Department of Energy's Wind Energy Program.
Thresher, R. W.; Hock, S. M.; Loose, R. R.; Goldman, P.
Nonlinear control of variable speed wind turbines for power regulation
A nonlinear controller has been designed for variable speed wind turbines electric power regulation. The efficiency and reliability of wind power is shown to be depending on the applied control strategy of the wind turbine. Up to now, classical regulation is implemented only. However, under sudden wind profile variations, the wind turbine performance decrease which may cause troubles in the
Boubekeur Boukhezzar; Houria Siguerdidjane
A gas turbine component is described consisting of a non-symmetrical body made of material selected from the group consisting of nickel-base superalloy, cobalt-base superalloy and iron-base superalloy and an alloy coating metallurgically bonded by an interdiffusion zone and providing the outer surface for the coated body. The composition of the coating consists essentially of (in weight percent) about 43% chromium; about 0.1% yttrium, and oxides; up to 15% silicon; less than the percentage of aluminum which would be required to form a continuous film of aluminum oxide over the outer surface, and the balance essentially cobalt. The concentration of chromium is uniform on a macroscopic scale across the thickness of the coating.
Luthra, K.L.
Diffuser for augmenting a wind turbine
A diffuser for augmenting a wind turbine having means for energizing the boundary layer at several locations along the diffuser walls is improved by the addition of a short collar extending radially outward from the outlet of the diffuser.
Foreman, Kenneth M. (North Bellmore, NY) [North Bellmore, NY; Gilbert, Barry L. (Westbury, NY) [Westbury, NY
Wind Turbine Test Micon 55 KW.
The report describes standard measurements performed on a Micon 55 kW wind turbine. The measurements carried out and reported here comprises the power output, system efficiency, energy production, transmission efficiency, rotor power, rotor efficiency, st...
T. Friis Pedersen
Wind Turbine Test Danwin 23 Prototype.
The report describes standard measurements performed on a Danwin 23 180 kW prototype wind turbine. The measurements carried out and reported here comprises the power output, system efficiency, energy production, transmission efficiency, rotor power, rotor...
T. Friis Pedersen S. Markkilde Petersen U. Schmidt Paulsen P. Voelund
Darrieus Wind-Turbine Airfoil Configurations.
The purpose of this study was to determine what aerodynamic performance improvement, if any, could be achieved by judiciously choosing the airfoil sections for Darrieus wind turbine blades. Analysis was limited to machines using two blades of infinite asp...
P. G. Migliore J. R. Fritschen
Vertical Axis Wind Turbine Foundation parameter study
The dynamic failure criterion governing the dimensions of prototype Vertical Axis Wind Turbine Foundations is treated as a variable parameter. The resulting change in foundation dimensions and costs is examined.
Lodde, P.F.
Dynamically Reconfigurable Wind Turbine Blade Assembly.
A dynamically reconfigurable wind turbine blade assembly includes a plurality of reconfigurable blades mounted on a hub, an actuator fixed to each of the blades and adapted to effect the reconfiguration thereof, and an actuator power regulator for regulat...
C. H. Beauchamp S. A. Huyer S. J. Plunkett
New Method for Dual-Axis Fatigue Testing of Large Wind Turbine Blades Using Resonance Exicitation and Spectral Loading.
The blades of a wind turbine are generally considered to be the most critical component of the wind turbine system. The fundamental purpose of performing fatigue tests on wind turbine blades is to demonstrate that a blade, when manufactured to a certain s...
D. White
New Method for Dual-Axis Fatigue Testing of Large Wind Turbine Blades Using Resonance Excitation and Spectral Loading
The blades of a wind turbine are generally considered to be the most critical component of the wind turbine system. The fundamental purpose of performing fatigue tests on wind turbine blades is to demonstrate that a blade, when manufactured to a certain set of specifications, has the prescribed reliability and service life. The purpose of the research conducted for this
Wind Turbine Safety and Function Test Report for the Gaia-Wind 11-kW Wind Turbine
This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers to wind energy expansion by providing independent testing results for small wind turbines (SWT). In total, four turbines were tested at the National Wind Technology Center (NWTC) as a part of this project. Safety and function testing is one of up to five tests performed on the turbines, including power performance, duration, noise, and power-quality tests. The results of the testing provide the manufacturers with reports that can be used for small wind turbine certification. The test equipment includes a Gaia-Wind 11-kW wind turbine mounted on an 18-m monopole tower. Gaia-Wind Ltd. manufactured the turbine in Denmark. The system was installed by the NWTC site operations group with guidance and assistance from Gaia-Wind.
Huskey, A.; Bowen, A.; Jager, D.
Coupled Dynamic Modeling of Floating Wind Turbine Systems: Preprint
This article presents a collaborative research program that the Massachusetts Institute of Technology (MIT) and the National Renewable Energy Laboratory (NREL) have undertaken to develop innovative and cost-effective floating and mooring systems for offshore wind turbines in water depths of 10-200 m. Methods for the coupled structural, hydrodynamic, and aerodynamic analysis of floating wind turbine systems are presented in the frequency domain. This analysis was conducted by coupling the aerodynamics and structural dynamics code FAST [4] developed at NREL with the wave load and response simulation code WAMIT (Wave Analysis at MIT) [15] developed at MIT. Analysis tools were developed to consider coupled interactions between the wind turbine and the floating system. These include the gyroscopic loads of the wind turbine rotor on the tower and floater, the aerodynamic damping introduced by the wind turbine rotor, the hydrodynamic damping introduced by wave-body interactions, and the hydrodynamic forces caused by wave excitation. Analyses were conducted for two floater concepts coupled with the NREL 5-MW Offshore Baseline wind turbine in water depths of 10-200 m: the MIT/NREL Shallow Drafted Barge (SDB) and the MIT/NREL Tension Leg Platform (TLP). These concepts were chosen to represent two different methods of achieving stability to identify differences in performance and cost of the different stability methods. The static and dynamic analyses of these structures evaluate the systems' responses to wave excitation at a range of frequencies, the systems' natural frequencies, and the standard deviations of the systems' motions in each degree of freedom in various wind and wave environments. This article in various wind and wave environments. This article explores the effects of coupling the wind turbine with the floating platform, the effects of water depth, and the effects of wind speed on the systems' performance. An economic feasibility analysis of the two concepts was also performed. Key cost components included the material and construction costs of the buoy; material and installation costs of the tethers, mooring lines, and anchor technologies; costs of transporting and installing the system at the chosen site; and the cost of mounting the wind turbine to the platform. The two systems were evaluated based on their static and dynamic performance and the total system installed cost. Both systems demonstrated acceptable motions, and have estimated costs of $1.4-$1.8 million, not including the cost of the wind turbine, the power electronics, or the electrical transmission.
Wayman, E. N.; Sclavounos, P. D.; Butterfield, S.; Jonkman, J.; Musial, W.
Wind direction change criteria for wind turbine design
A method is presented for estimating the root mean square (rms) value of the wind direction change, Delta Theta (tau) = theta (tau + tau) - Theta (tau), that occurs over the swept area of wind turbine rotor systems. An equation is also given for the rms value of the wind direction change that occurs at a single point in
W. C. Cliff
Mars Technologies Spawn Durable Wind Turbines.
To develop and test wind power technology for use on Mars, Ames Research Center turned to Northern Power Systems (NPS), based in Barre, Vermont. Ames awarded NPS an SBIR contract so the company could enhance their turbine.s function. Today, over 200 NASA-...
Computational studies of horizontal axis wind turbines
A numerical technique has been developed for efficiently simulating fully three-dimensional viscous fluid flow around horizontal axis wind turbines (HAWT) using a zonal approach. The flow field is viewed as a combination of viscous regions, inviscid regions and vortices. The method solves the costly unsteady Reynolds averaged Navier-Stokes (RANS) equations only in the viscous region around the turbine blades. It
Guanpeng Xu
Modeling stochastic wind loads on vertical axis wind turbines
The Vertical Axis Wind Turbine (VAWT) is a machine which extracts energy from the wind. Since random turbulence is always present, the effect of this turbulence on the wind turbine fatigue life must be evaluated. This problem is approached by numerically simulating the turbulence and calculating, in the time domain, the aerodynamic loads on the turbine blades. These loads are reduced to the form of power and cross spectral densities which can be used in standard linear structural analysis codes. The relative importance of the turbulence on blade loads is determined.
Passively cooled direct drive wind turbine
A wind turbine is provided that passively cools an electrical generator. The wind turbine includes a plurality of fins arranged peripherally around a generator house. Each of the fins being oriented at an angle greater than zero degrees to allow parallel flow of air over the fin. The fin is further tapered to allow a constant portion of the fin to extend beyond the air stream boundary layer. Turbulence initiators on the nose cone further enhance heat transfer at the fins.
Costin, Daniel P. (Chelsea, VT)
Mod2 wind turbine field operations experience
The Mod-2 wind turbine is now in a 2-year research\\/experimental operations phase which offers a unique opportunity to study the effects of single and multiple wind turbines interacting with each other, the power grid, and the environment. This paper addresses the field operations and research testing experienced at the Mod-2 Cluster Goodnoe Hills Research Test Site near Goldendale, WA. Field
L. H. Gordon
Wind Turbine Reliability: Understanding and Minimizing Wind Turbine Operation and Maintenance Costs.
Wind turbine system reliability is a critical factor in the success of a wind energy project. Poor reliability directly affects both the project's revenue stream through increased operation and maintenance (O&M) costs and reduced availability to generate ...
C. A. Walford
Site calibration for the wind turbine performance evaluation
The accurate wind speed information at the hub height of a wind turbine is very essential to the exact estimation of the wind\\u000a turbine power performance testing. Several methods on the site calibration, which is a technique to estimate the wind speed\\u000a at the wind turbineÆs hub height based on the measured wind data using a reference meteorological mast, are
Yoonsu Nam; Neungsoo Yoo; Jungwan Lee
The blades of a wind turbine are generally considered to be the most critical component of the wind turbine system. The fundamental purpose of performing fatigue tests on wind turbine blades is to demonstrate that a blade, when manufactured to a certain set of specifications, has the prescribed reliability and service life. The purpose of the research conducted for this project is the advancement of knowledge and capabilities in the area of wind turbine blade fatigue testing.
White, D.
Modified Adaptive Control for Region 3 Operation in the Presence of Wind Turbine Structural Modes
Many challenges exist for the operation of wind turbines in an efficient manner that is reliable and avoids component fatigue and failure. Turbines operate in highly turbulent environments resulting in aerodynamic loads that can easily excite turbine structural modes, possibly causing component fatigue and failure. Wind turbine manufacturers are highly motivated to reduce component fatigue and failure that can lead to loss of revenue due to turbine down time and maintenance costs. The trend in wind turbine design is toward larger, more flexible turbines that are ideally suited to adaptive control methods due to the complexity and expense required to create accurate models of their dynamic characteristics. In this paper, we design an adaptive collective pitch controller for a high-fidelity simulation of a utility-scale, variable-speed horizontal axis wind turbine operating in Region 3. The objective of the adaptive pitch controller is to regulate generator speed, accommodate wind gusts, and reduce the excitation of structural modes in the wind turbine. The control objective is accomplished by collectively pitching the turbine blades. The adaptive collective pitch controller for Region 3 was compared in simulations with a baseline classical Proportional Integrator (PI) collective pitch controller. The adaptive controller will demonstrate the ability to regulate generator speed in Region 3, while accommodating gusts, and reducing the excitation of certain structural modes in the wind turbine.
Frost, Susan Alane; Balas, Mark J.; Wright, Alan D.
Reliability-Centered Maintenance for Wind Turbines Based on Statistical Analysis and Practical Experience
The concept of reliability-centered maintenance (RCM) is applied to the two wind-turbine models Vestas V44-600 kW and V90-2MW. The executing RCM workgroup includes an owner and operator of the analyzed wind turbines, a maintenance service provider, a provider of condition-monitoring services, and wind-turbine component supplier as well as researchers at academia. Combining the results of failure statistics and assessment of
Katharina Fischer; Francois Besnard; Lina Bertling
Detection of nocturnal coherent turbulence in the US Great Plains and effects on wind turbine fatigue
Strong low-level jet winds that develop in the nocturnal stable boundary layer (SBL) create some of the most energetic wind energy resources in Great Plains of North America. These stratified flows, however, can cause strong wind shear and veer across wind turbine rotors. Additionally, turbulent bursting events triggered by strong vertical wind shear can lead to fatigue and damage of wind turbine blades and components, increasing maintenance costs and reducing wind turbine power production. Coherent structures which are the signature of turbulent bursting events can be observed in heavily instrumented wind farms and in high-resolution simulations. Large-scale adoption of wind energy will benefit from the ability to predict these turbulence events with limited in-situ data. By identifying signatures of these bursting events, new turbine control technologies could be used to reduce wind turbine damage and increase overall wind farm energy yield (for example using algorithms with the ability to proactively and independently pitch blades). This research analyzes SBL turbulence in the Great Plains to develop methods to identify these structures at wind farms. Nested large-eddy simulations down to about 20m horizontal resolution are performed and compared to high-resolution Doppler wind LIDAR data (1 Hz) to determine if the model is able to create similar wind and turbulence conditions. Wavelet analysis of the LIDAR and model wind fields is used to detect coherent turbulent structures at frequencies that could be potentially damaging for wind turbines and provide guidance for design of turbine control technologies.
Dvorak, M. J.; Wiersema, D. J.; Zhou, B.; Chow, F. K.
Wind tunnel study on wind and turbulence intensity profiles in wind turbine wake
In recent years, there has been a rapid development of the wind farms in Japan. It becomes very important to investigate the\\u000a wind turbine arrangement in wind farm, in order that the wake of one wind turbine does not to interfere with the flow in other\\u000a wind turbines. In such a case, in order to achieve the highest possible efficiency
Takao Maeda; Yasunari Kamada; Junsuke Murata; Sayaka Yonekura; Takafumi Ito; Atsushi Okawa; Tetsuya Kogaki
Control of wind turbines: Past, present, and future
We review the objectives and techniques used in the control of horizontal axis wind turbines at the individual turbine level, where controls are applied to the turbine blade pitch and generator. The turbine system is modeled as a flexible structure operating in the presence of turbulent wind disturbances. Some overview of the various stages of turbine operation and control strategies
Jason H. Laks; Lucy Y. Pao; Alan D. Wright
As wind energy becomes a larger portion of the world's energy portfolio and wind turbines become larger and more expensive, wind turbine control systems play an ever more prominent role in the design and deployment of wind turbines. The goals of traditional wind turbine control systems are maximizing energy production while protecting the wind turbine components. As more wind generation is installed there is an increasing interest in wind turbines actively controlling their power output in order to meet power setpoints and to participate in frequency regulation for the utility grid. This capability will be beneficial for grid operators, as it seems possible that wind turbines can be more effective at providing some of these services than traditional power plants. Furthermore, establishing an ancillary market for such regulation can be beneficial for wind plant owner/operators and manufacturers that provide such services. In this tutorial paper we provide an overview of basic wind turbine control systems and highlight recent industry trends and research in wind turbine control systems for grid integration and frequency stability.
Aho, J.; Buckspan, A.; Laks, J.; Fleming, P.; Jeong, Y.; Dunne, F.; Churchfield, M.; Pao, L.; Johnson, K.
Tribological advancements for reliable wind turbine performance.
Wind turbines have had various limitations to their mechanical system reliability owing to tribological problems over the past few decades. While several studies show that turbines are becoming more reliable, it is still not at an overall acceptable level to the operators based on their current business models. Data show that the electrical components are the most problematic; however, the parts are small, thus easy and inexpensive to replace in the nacelle, on top of the tower. It is the tribological issues that receive the most attention as they have higher costs associated with repair or replacement. These include the blade pitch systems, nacelle yaw systems, main shaft bearings, gearboxes and generator bearings, which are the focus of this review paper. The major tribological issues in wind turbines and the technological developments to understand and solve them are discussed within. The study starts with an overview of fretting corrosion, rolling contact fatigue, and frictional torque of the blade pitch and nacelle yaw bearings, and references to some of the recent design approaches applied to solve them. Also included is a brief overview into lubricant contamination issues in the gearbox and electric current discharge or arcing damage of the generator bearings. The primary focus of this review is the detailed examination of main shaft spherical roller bearing micropitting and gearbox bearing scuffing, micropitting and the newer phenomenon of white-etch area flaking. The main shaft and gearbox are integrally related and are the most commonly referred to items involving expensive repair costs and downtime. As such, the latest research and developments related to the cause of the wear and damage modes and the technologies used or proposed to solve them are presented. PMID:20855322
Kotzalas, Michael N; Doll, Gary L
Vertical axis wind turbine designed aerodynamically at Tokai University
The advantages of the vertical axis wind turbine over conventional propeller-type wind turbines are listed, among them the fact that the turbine is free from the gyroscopic loading accompanied by wind direction tracking. Special attention is given to the straight-wing type vertical axis turbine, which is thought to be particularly advantageous. Also discussed are the characteristics of the blade. It
Y. Kato; K. Seki; Y. Shimizu
Nation's tallest VAWT (Vertical Axis Wind Turbine) turning out the watts. [Vertical Axis Wind Turbine
This article describes the development of the tallest and most powerful windmill of its kind in the U.S. Known as a Vertical Axis Wind Turbine (VAWT), the machine is meant for testing new concepts in vertical axis turbine design. As part of its overall testing program, the turbine will supply electricity to automated water pumps used in irrigation research at
Infrasound emission generated by wind turbines
Aerodynamic noise emissions from the continuously growing number of wind turbines in Germany are creating increasing problems for infrasound recording systems. Such systems are equipped with highly sensitive micro pressure sensors, which are accurately measuring acoustic signals in a frequency range inaudible to humans. At infrasound station IGADE, north of Bremen, a constantly increasing background noise has been observed throughout the years since its installation in 2005. The spectral peaks are reflecting well the blade passing harmonics, which vary with prevailing wind speeds. Overall, a decrease is noted for the infrasound array's detection capability. This aspect is particularly important for the other two sites of the German infrasound stations I26DE in the Bavarian Forest and I27DE in Antarctica, because plans for installing wind turbines near these locations are being under discussion. These stations are part of the International Monitoring System (IMS) verifying compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), and have to meet stringent specifications with respect to infrasonic background noise. Therefore data obtained during a field experiment with mobile micro-barometer stations for measuring the infrasonic pressure level of a single horizontal-axis wind turbine have been revisited. The results of this experiment successfully validate a theoretical model which estimates the generated sound pressure level of wind turbines and makes it possible to specify the minimum allowable distance between wind turbines and infrasound stations for undisturbed recording. Since the theoretical model also takes wind turbine design parameters into account, suitable locations for planned infrasound stations outside the determined disturbance range can be found, which will be presented; and vice versa, the model calculations' results for fixing the minimum distance for wind turbines planned for installation in the vicinity of an existing infrasound array.
Ceranna, Lars; Pilger, Christoph
Jet spoiler arrangement for wind turbine
An air jet spoiler arrangement is provided for a Darrieus-type vertical axis wind-powered turbine. Air is drawn into hollow turbine blades through air inlets at the end thereof and is ejected in the form of air jets through small holes or openings provided along the lengths of the blades. The air jets create flow separation at the surfaces of the turbine blades, thereby including stall conditions and reducing the output power. A feedback control unit senses the power output of the turbine and controls the amount of air drawn into the air inlets accordingly.
Cyrus, J.D.; Kadlec, E.G.; Klimas, P.C.
An air jet spoiler arrangement is provided for a Darrieus-type vertical axis wind-powered turbine. Air is drawn into hollow turbine blades through air inlets at the ends thereof and is ejected in the form of air jets through small holes or openings provided along the lengths of the blades. The air jets create flow separation at the surfaces of the turbine blades, thereby inducing stall conditions and reducing the output power. A feedback control unit senses the power output of the turbine and controls the amount of air drawn into the air inlets accordingly.
Cyrus, Jack D. (Corrales, NM) [Corrales, NM; Kadlec, Emil G. (Albuquerque, NM) [Albuquerque, NM; Klimas, Paul C. (Albuquerque, NM) [Albuquerque, NM
Vertical axis wind turbine control strategy
Early expensive in automatic operation of the Sandia 17-m vertical axis research wind turbine (VAWT) has demonstrated the need for a systematic study of control algorithms. To this end, a computer model has been developed that uses actual wind time series and turbine performance data to calculate the power produced by the Sandia 17-m VAWT operating in automatic control. The model has been used to investigate the influence of starting algorithms on annual energy production. The results indicate that, depending on turbine and local wind characteristics, a bad choice of a control algorithm can significantly reduce overall energy production. The model can be used to select control algorithms and threshold parameters that maximize long-term energy production. An attempt has been made to generalize these results from local site and turbine characteristics to obtain general guidelines for control algorithm design.
McNerney, G.M.
On the power regulation of small wind turbines based on experience with small Danish wind turbines
The state of development of the small wind turbines on the Danish market covering a range of 10 to 55 kW, of which approximately 500 are in operation is discussed. A typical feature of Danish small wind turbines is the regulation of the power output by stalling of the rotor blades. The merits of the stall regulation are discussed with
P. Lundsager
Innovative wind turbines. Circulation controlled vertical axis wind turbine. Progress report, March 1December 31, 1976
Theoretical and experimental research efforts in evaluating an innovative concept for vertical axis wind turbines (VAWT) are described. The concept is that of using straight blades composed of circulation controlled airfoil sections. The theoretical analysis has been developed to determine the unsteady lift and moment characteristics of multiple-blade cross-flow wind turbines. To determine the drag data needed as input to
R. E. Walters; J. B. Fanucci; P. W. Hill; P. G. Migliore; W. Squire; T. L. Waltz
Fault-Tolerant Control of Wind Turbine Systems - A Review
Wind turbine systems are complex and remotely- installed structures which are subject to many possible faults in the existed components. Early fault detection, isolation and successful controller reconfiguration can considerably increase the performance in faulty conditions and prevent abysmal failures in the system. This paper gives an overview of recent progress in theory and methods to analyze and design fault-
Sajjad Pourmohammad; Afef Fekih
How to protect a wind turbine from lightning
This book discusses techniques for reducing the chances of lightning damage to wind turbines. The methods of providing a ground for a lightning strike are discussed. Then details are given on ways to protect electronic systems, generating and power equipment, blades, and mechanical components from direct and nearby lightning strikes.
Dodd, C.W.; McCalla, T. Jr.; Smith, J.G.
Evaluation of RCAS Inflow Models for Wind Turbine Analysis
The finite element structural modeling in the Rotorcraft Comprehensive Analysis System (RCAS) provides a state-of-the-art approach to aeroelastic analysis. This, coupled with its ability to model all turbine components, results in a methodology that can simulate complex system interactions characteristic of large wind. In addition, RCAS is uniquely capable of modeling advanced control algorithms and the resulting dynamic responses.
J. Tangler; G. Bir
Power electronics converters for wind turbine systems
The steady growth of installed wind power which reached 200 GW capacity in 2010, together with the up-scaling of the single wind turbine power capability - 7 MW's has been announced by manufacturers - has pushed the research and development of power converters towards full scale power conversion, lowered cost pr kW, and increased power density and the need for
F. Blaabjerg; M. Liserre; K. Ma
Wear Analysis of Wind Turbine Gearbox Bearings
The objective of this effort was to investigate and characterize the nature of surface damage and wear to wind turbine gearbox bearings returned from service in the field. Bearings were supplied for examination by S. Butterfield and J. Johnson of the National Wind Technology Center (NREL), Boulder, Colorado. Studies consisted of visual examination, optical and electron microscopy, dimensional measurements of
Peter Julian Blau; Larry R Walker; Hanbing Xu; Randy J Parten; Jun Qu; Tom Geer
Multilevel converters for 10 MW Wind Turbines
Several promising multi-level converter configurations for 10 MW Wind Turbines both with direct drive and one-stage gear box drive using Permanent Magnet Synchronous Generator (PMSG) are proposed, designed and compared. Reliability is a crucial indicator for large scale wind power converters, therefore the evaluations are mainly focused on the power device thermal performances, which are closely related to the life
Ke Ma; Frede Blaabjerg
A review of large wind turbine systems
Research areas in the design and operation of large wind turbines in the U.S. and Europe are detailed, with attention given to current and completed programs. Theoretical work in the U.S. is focused on aerodynamics of blades, structural dynamics, control systems, and safety through safe life design, redundancy, and quality assurance. Work is continuing on wind characteristics over the rotor
H. Selzer; J. I. Lerner
The Wind Energy Technology Department at Sandia National Laboratories (SNL) focuses on producing innovations in wind turbine blade technology to enable the development of longer blades that are lighter, more structurally and aerodynamically efficient, and impart reduced loads to the system. A large part of the effort is to characterize the properties of relevant composite materials built with typical manufacturing
Thomas D. Ashwill; Joshua A. Paquette
Radar signature control of wind turbine generators
Many of the prime locations for wind farms in the UK are on exposed landscapes close to regional airports. However, planning permission for such installations is often being denied because the moving blades of the wind turbines interfere with the operation of airport radar systems. Airport surveillance radars track the position and speed of aircraft in their surrounding airspace using
A. Tennant; B. Chambers
A sensorless control for wind turbine
This paper presents a sensorless control for a stall regulated variable speed wind turbine, where the speed reference is obtained from the estimated aerodynamic torque. The LQG\\/LTR methodology is applied to the design of an optimal discrete-time feedback controller for a Wind Energy Conversion System, aiming to maximize the efficiency on energy conversion and to minimize the detrimental dynamic loads
Ronilson Rocha
Dynamic Characterization Testing of Wind Turbines.
The U.S. Department of Energy (DOE), in conjunction with the U.S. wind industry, is supporting the development and commercialization of utility-grade wind turbines. Under the Certification Program, the DOE, through the National Renewable Energy Laboratory...
R. Osgood
Practical aspects for small wind turbine applications
SUMMARY Low power wind turbines (WTs) are less widely applied compared to medium and high power systems. These WTs are suitable for decentralized applications and can provide electricity to residential buildings, hotels, greenhouses, etc. These WTs can be of horizontal or vertical rotor axis, must be of low cut-in wind speed and flexible in installation and operation, considering their limits
Y. Tripanagnostopoulos; A. Christodoulou; S. Tselepis; M. Souliotis; J. K. Tonui
Technical Description of the NIBE Wind Turbines.
As part of the wind power programme of the Danish Ministry of Energy and the electric utilities two wind turbines have been constructed and placed at Nibe Bredning in North Jutland. This technical description has been made to give a total survey of the co...
Research and development for shrouded wind turbines
A special shroud, designed for enclosing a wind turbine in order to exploit wind power as economically as possible, is presented. Several geometries, including the short diffuser shroud and the circular wing shroud, are discussed, and it is shown that a significant power augmentation can be achieved with a fairly compact shroud. Up to an 80% improvement in the shroud
O. Igra
Tailored Airfoils for Vertical Axis Wind Turbines.
The evolution of a family of airfoil sections designed to be used as blade elements of a vertical axis wind turbine (VAWT) is described. This evolution consists of extensive computer simulation, wind tunnel testing and field testing. The process reveals t...
P. C. Klimas
Subhourly wind forecasting techniques for wind turbine operations
Three models for making automated forecasts of subhourly wind and wind power fluctuations were examined to determine the models' appropriateness, accuracy, and reliability in wind forecasting for wind turbine operation. Such automated forecasts appear to have value not only in wind turbine control and operating strategies, but also in improving individual wind turbine control and operating strategies, but also in improving individual wind turbine operating strategies (such as determining when to attempt startup). A simple persistence model, an autoregressive model, and a generalized equivalent Markhov (GEM) model were developed and tested using spring season data from the WKY television tower located near Oklahoma City, Oklahoma. The three models represent a pure measurement approach, a pure statistical method and a statistical-dynamical model, respectively. Forecasting models of wind speed means and measures of deviations about the mean were developed and tested for all three forecasting techniques for the 45-meter level and for the 10-, 30- and 60-minute time intervals. The results of this exploratory study indicate that a persistence-based approach, using onsite measurements, will probably be superior in the 10-minute time frame. The GEM model appears to have the most potential in 30-minute and longer time frames, particularly when forecasting wind speed fluctuations. However, several improvements to the GEM model are suggested. In comparison to the other models, the autoregressive model performed poorly at all time frames; but, it is recommended that this model be upgraded to an autoregressive moving average (ARMA or ARIMA) model. The primary constraint in adapting the forecasting models to the production of wind turbine cluster power output forecasts is the lack of either actual data, or suitable models, for simulating wind turbine cluster performance.
Wegley, H.L.; Kosorok, M.R.; Formica, W.J.
Evaluation of micro-wind turbine aerodynamics, wind speed sampling interval and its spatial variation
Large wind turbines are usually installed in areas where wind speed distributions have been observed long enough to make sure of their high efficiency. However, micro-wind turbines are mostly used in areas where wind conditions are not necessarily favourable for efficient power production. Therefore, micro-wind turbines require specific designs to work effectively in low and turbulent wind resource areas. However,
A. Makkawi; AN Celik; T. Muneer
Integrating Systems Health Management with Adaptive Controls for a Utility-Scale Wind Turbine
Increasing turbine up-time and reducing maintenance costs are key technology drivers for wind turbine operators. Components within wind turbines are subject to considerable stresses due to unpredictable environmental conditions resulting from rapidly changing local dynamics. Systems health management has the aim to assess the state-of-health of components within a wind turbine, to estimate remaining life, and to aid in autonomous decision-making to minimize damage. Advanced adaptive controls can provide the mechanism to enable optimized operations that also provide the enabling technology for Systems Health Management goals. The work reported herein explores the integration of condition monitoring of wind turbine blades with contingency management and adaptive controls. Results are demonstrated using a high fidelity simulator of a utility-scale wind turbine.
Frost, Susan A.; Goebel, Kai; Trinh, Khanh V.; Balas, Mark J.; Frost, Alan M.
Voltage grid support of DFIG wind turbines during grid faults
The fault ride-through and grid support capabilities of the doubly fed induction generator (DFIG) wind turbines address primarily the design of DFIG wind turbine control with special focus on power converters protection and on voltage control issues. This paper presents the design of a voltage control strategy for DFIG wind turbines, which enhances the fault ride-through capability of DFIG wind
Anca D. Hansen; Gabriele Michalke
Modeling the effects of wind turbines on radar returns
Wind turbines located near radar installations can significantly interfere with a radar's ability to detect its intended targets. In order to better understand and mitigate the adverse effects of wind turbines on radar, the government and wind farm community need tools that can be used to analyze the radar returns from wind turbines. Remcom's XGtd« software is a high frequency
R. Ryan Ohs; Gregory J. Skidmore; Gary Bedrosian
Grid integration impacts on wind turbine design and development
This paper presents an overall perspective on contemporary issues like wind power plants and grid integration. The purpose is to present and discuss the impacts of emerging new grid connection requirements on modern wind turbines. The grid integration issue has caused several new challenges to the wind turbine design and development. The survival of different wind turbine concepts and controls
A. D. Hansen; N. A. Cutululis; P. Sorensen; F. Iov
Optimization of Wind Turbine Performance With Data-Driven Models
This paper presents a multiobjective optimization model of wind turbine performance. Three different objectives, wind power output, vibration of drive train, and vibration of tower, are used to evaluate the wind turbine performance. Neural network models are developed to capture dynamic equations modeling wind turbine performance. Due to the complexity and nonlinearity of these models, an evolutionary strategy algorithm is
Andrew Kusiak; Zijun Zhang; Mingyang Li
Large-eddy simulation (LES), coupled with a wind-turbine model, is used to investigate the characteristics of wind turbine wakes in turbulent boundary layers under different thermal stratification conditions. The subgrid-scale (SGS) stress and SGS heat flux are parameterized using scale-dependent Lagrangian dynamic models (Stoll and Porte-Agel, 2006). The turbine-induced lift and drag forces are parameterized using two models: an actuator disk model (ADM) that distributes the force loading on the rotor disk; and an actuator line model (ALM) that distributes the forces on lines that follow the position of the blades. Simulation results are compared to wind-tunnel measurements collected with hot-wire and cold-wire anemometry in the wake of a miniature 3-blade wind turbine at the St. Anthony Falls Laboratory atmospheric boundary layer wind tunnel. In general, the characteristics of the wakes simulated with the proposed LES framework are in good agreement with the measurements. The ALM is better able to capture vortical structures induced by the blades in the near-wake region. Our results also show that the scale-dependent Lagrangian dynamic SGS models are able to account, without tuning, for the effects of local shear and flow anisotropy on the distribution of the SGS model coefficients.
Porte-Agel, Fernando; Wu, Yu-Ting; Chamorro, Leonardo
Load attenuating passively adaptive wind turbine blade
A method and apparatus for improving wind turbine performance by alleviating loads and controlling the rotor. The invention employs the use of a passively adaptive blade that senses the wind velocity or rotational speed, and accordingly modifies its aerodynamic configuration. The invention exploits the load mitigation prospects of a blade that twists toward feather as it bends. The invention includes passively adaptive wind turbine rotors or blades with currently preferred power control features. The apparatus is a composite fiber horizontal axis wind-turbine blade, in which a substantial majority of fibers in the blade skin are inclined at angles of between 15 and 30 degrees to the axis of the blade, to produces passive adaptive aeroelastic tailoring (bend-twist coupling) to alleviate loading without unduly jeopardizing performance.
Veers, Paul S. (Albuquerque, NM); Lobitz, Donald W. (Albuquerque, NM)
Active robust control of wind turbines
The research work conducted in this thesis focuses on robustness of wind energy conversion system with respect to faults in pitch actuator in order to prevent unnecessary emergency shutdown, and keep the turbine operational without significant inefficiency in its overall performance. The objective is to investigate the feasibility of using a fault estimator and a light detection and ranging (LIDAR) system as additional sensors to design a suitable control system for wind turbines. Robust control technique is used to address these issues. Three controllers are proposed in this work that try to address sources of inaccuracy in wind turbine operation: An active fault tolerant controller is first designed using a fault estimator. It is shown that a set of locally robust controllers with respect to the fault, together with a suitable smooth mixing approach, manages to overcome the problem of faults in the pitch actuator. To address the wind-dependent behavior of turbines, a second controller is designed using the LIDAR sensor. In this configuration, LIDAR provides the look ahead wind information and generates a smooth scheduling signal to provide active robustness with respect to the changes in wind speed. Lastly, utilizing both the fault estimator and LIDAR, a 2-dimensional wind-dependent active fault tolerant controller is developed to control the wind turbine in region 3 of operation. The feasibility of the proposed ideas is verified in simulation. For this purpose, the US National Renewable Energy Laboratory's FAST code is used to model the 3-balded controls advanced research turbine. A discussion on practical considerations and ideas for future work are also presented.
Rezaei, Vahid
Innovative wind turbines. The circulation control vertical axis wind turbine. Final report, May 1, 1978December 31, 1979
An indoor facility was developed for use in the aerodynamic testing of Darrieus wind turbine blades. A three-component internal strain gage balance was used to deduce lift, drag and moment coefficients of blades whose angle of attack, chord to radius ratio and Reynolds number can be systematically varied. The unusual flow field of this test environment necessitates unique downwash corrections
R. E. Walters; P. G. Migliore; W. P. Wolfe
Control of wind turbines with 'Smart' rotors: proof of concept & LPV subspace identification
Active control is becoming more and more important for the wind energy community. If we compare the 'old' stall regulated turbines with today's individual pitch controlled turbines we see that the loads can be considerably reduced, leading to lighter or larger turbines. However, limited actuator bandwidth and component fatigue impose significant constraints on the pitch system. Furthermore, with the trend
J. W. Van Wingerden
Blade System Design Studies Volume I: Composite Technologies for Large Wind Turbine Blades
As part of the U.S. Department of Energy's Wind Partnerships for Advanced Component Technologies (WindPACT) program, Global Energy Concepts LLC (GEC) is performing a study concerning innovations in materials, processes and structural configurations for application to wind turbine blades in the multi-megawatt range. The project team for this work includes experts in all areas of wind turbine blade design, analysis,
In recent years, there has been a rapid development of the wind farms in Japan. It becomes very important to investigate the wind turbine arrangement in wind farm, in order that the wake of one wind turbine does not to interfere with the flow in other wind turbines. In such a case, in order to achieve the highest possible efficiency from the wind, and to install as many as possible wind turbines within a limited area, it becomes a necessity to study the mutual interference of the wake developed by wind turbines. However, there is no report related to the effect of the turbulence intensity of the external flow on the wake behind a wind turbine generated in the wind tunnel. In this paper, the measurement results of the averaged wind profile and turbulence intensity profile in the wake in the wind tunnel are shown when the turbulence intensity of the external wind was changed. The wind tunnel experiment is performed with 500mm-diameter two-bladed horizontal axis wind turbine and the wind velocity in wake is measured by an I-type hot wire probe. As a result, it is clarified that high turbulence intensities enable to the entrainment of the main flow and the wake and to recover quickly the velocity in the wake.
Maeda, Takao; Kamada, Yasunari; Murata, Junsuke; Yonekura, Sayaka; Ito, Takafumi; Okawa, Atsushi; Kogaki, Tetsuya
Wind Turbine Test. Wind Matic WM 17S.
The report describes standard measurements performed on a Wind-Matic WM 17S, 75 kW wind turbine. The measurements carried out and reported here comprises the power output, system efficiency, energy production, transmission efficiency, rotor power, rotor e...
Research of CMC Application to Turbine Components
Ceramics Matrix Composite (CMC) is an advanced material that has low density and high temperature capability. Application of CMC to turbine components is expected to reduce the weight and the fuel consumption of aircraft jet engine. Research and development was conducted to apply this material to the turbine shroud and vane. Coating technology was developed to protect the CMC shroud
ARAKI Takahito
DDDAS - SMTP: A Framework for the Dynamic Data Driven Fault Diagnosis of Wind Turbine Systems
The overall goal of this NSF research is to develop a dynamic data driven fault diagnosis framework for wind turbine systems. An important component of the research is the development of wireless sensor nodes that will be deployed inside a wind turbine to collect vibration and acoustic signals. To enhance the research and education, an IREE program has been added
An Experimental and Theoretical Investigation of Micropiiting in Wind Turbine Gears and Bearings
In this research study, the micro-pitting related contact failures of wind turbine gearbox components were investigated both experimentally and theoretically. On the experimental side, a twin-disk type test machine was used to simulate wind turbine transmission contacts in terms of their kinematic (rolling and sliding speeds), surface roughnesses, material parameters and lubricant conditions. A test matrix that represents the ranges
Kahraman; Ahmet
Analysis of the mast contribution to the scattering pattern of wind turbines in the UHF band
The existing models to characterize signal scattering from wind turbines in the UHF band are based on the characteristics of the blades and do not consider the potential contribution from the mast. This paper aims to estimate the Radar Cross Section of a wind turbine and its components in order to determine the relative significance of the mast for the
I. Angulo; D. de la Vega; O. Rodriguez; O. Grande; D. Guerra; P. Angueira
A fatigue approach to wind turbine control
Conventional design of wind turbine controllers is focused on speed and produced electric power. As fatigue loads is an important design consideration, the resulting design is evaluated also with respect to the fatigue loads inflicted on the turbine structure. This is normally done by performing simulations using tools like FLEX, HAWC or FAST, followed by rainflow counting in the resulting time series. This procedure constitutes an iterative design procedure involving realisations of the stress processes in order to obtain the time series needed for fatigue estimates. The focus of this paper is the elimination of the need for process realisation. To this end, known techniques for approximative fatigue load assesment based on the spectral moments of the inflicted stress histories are applied. Assuming a linearised system model, we present a novel scheme for efficient computation of these spectral moments. The scheme is applied to obtain rapid evaluation of cost functions including fatigue loads, hereby allowing efficient numerical optimisation of the controller. Three different controller design examples are given, all defined directly in terms of component life times.
Hammerum, K.; Brath, P.; Poulsen, N. K.
Wind Turbine Safety and Function Test Report for the ARE 442 Wind Turbine
This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers of wind energy expansion by providing independent testing results for small turbines. In total, four turbines were tested at the National Wind Technology Center (NWTC) as a part of this project. Safety and function testing is one of up to five tests that were performed on the turbines, including power performance, duration, noise, and power quality tests. Test results provide manufacturers with reports that can be used for small wind turbine certification. The test equipment includes an ARE 442 wind turbine mounted on a 100-ft free-standing lattice tower. The system was installed by the NWTC Site Operations group with guidance and assistance from Abundant Renewable Energy.
van Dam, J.; Baker, D.; Jager, D.
Research areas in the design and operation of large wind turbines in the U.S. and Europe are detailed, with attention given to current and completed programs. Theoretical work in the U.S. is focused on aerodynamics of blades, structural dynamics, control systems, and safety through safe life design, redundancy, and quality assurance. Work is continuing on wind characteristics over the rotor disk and design criteria with regard to cost/benefits and tradeoffs involving various configurations and materials for the rotor blades, placement, pitch control, blade articulation, the tower, the drive train, the gear box, a quill shaft, generator type, and reliability and maintenance. Costing models are being developed. Test experience has been gained through the manufacture and operation of the five Mod 0A, one Mod-1, four Mod-2, and one WTS-4 wind turbines. The European work on blade loading, wind turbine dimensioning, materials, wind structure, environmental impacts, and economics are reviewed, together with the operational experience with the Gedser, two Nibe, the Tvind, and Growian machines. Several countries are also testing smaller wind turbines manufactured indigenously or imported.
Selzer, H.; Lerner, J. I.
Wind tunnel simulations of wind turbine wake interactions in neutral and stratified wind flow.
A second programme of work is about to commence as part of a further four years of funding for the UK-EPSRC SUPERGEN-Wind large-wind-farm consortium. The first part of the initial programme at Surrey was to establish and set up appropriate techniques for both on- and off-shore boundary layers (though with an emphasis on the latter) at a suitable scale, and to build suitable rotating model wind turbines. The EnFlo wind tunnel, a UK-NCAS special facility, is capable of creating scaled neutral, stable and unstable boundary layers in its 20m long working section. The model turbines are 1/300-scale of 5MW-size, speed controlled with phase-lock measurement capability, and the blade design takes into account low Reynolds-number effects. Velocity measurements are primarily made using two-component LDA, combined with a æcold-wire' probe in order to measure the local turbulent heat flux. Simulation of off-shore wakes is particularly constrained because i) at wind tunnel scale the inherently low surface roughness can be below that for fully rough conditions, ii) the power required to stratify the flow varies as the square of the flow speed, and could easily be impractically large, iii) low blade Reynolds number. The boundary layer simulations, set up to give near-equilibrium conditions in terms of streamwise development, and the model turbines have been designed against these constraints, but not all constraints can be always met simultaneously in practice. Most measurements so far have been made behind just one or two turbines in neutral off- and on-shore boundary layers, at stations up to 12 disk diameters downstream. These show how, for example, the wake of a turbine affects the development of the wake of a downwind turbine that is laterally off-set by say half or one diameter, and how the unaffected part from the first turbine merges with the affected wake of the second. As expected a lower level of atmospheric turbulence causes the wakes to develop and fill-in more slowly compared with the on-shore case. A turbine can also suppress the level of atmospheric turbulence below hub height. In neutral flow, the wakes grow in width and height. However, even in mild stable stratification the vertical development of the wake deficit can be completely inhibited; at least some reduction would be expected arising from the stabilizing influence on vertical fluctuations. The width in contrast develops at about the same rate. As anticipated, the wake development is slower still in the stable case because of the lower level ambient turbulence. The maximum deficit is at a lower height than it is for neutral flow. Various aspects of the turbulence in the wake have been investigated. Second-phase work will examine a larger number of wake-turbine and wake-wake interactions, make a more detailed study of how turbines alter the atmospheric turbulence, and examine more cases of stratification. Work is also in hand related to turbines in or near forested regions, and it is expected that aspects of the physics will have links with the effect a large wind farm will have on the ABL and on the wind resource for a downwind farm. The work will produce a series of test cases to assist in the development of better wake and wind resource prediction models as well as a better understanding of wake physics.
Hancock, P. E.; Pascheke, F.
Mod2 wind turbine field operations experiment
The three-machine, 7.5 MW Goodnoe Hills located near Goldendale, Washington and is now in a research\\/experimental operations phase that offers a unique opportunity to study the effects of single and multiple wind turbines interacting with each other, the power grid; and the environment. Following a brief description of the turbine and project history, this paper addresses major problem areas and
The three-machine, 7.5 MW Goodnoe Hills cluster, located near Goldendale, Washington, is now in a research\\/experimental operations phase that offers a unique opportunity to study the effects of single and multiple wind turbines interacting with each other, the power grid; and the environment. Following a brief description of the turbine and project history, this paper addresses major problem areas and
Mars Technologies Spawn Durable Wind Turbines
To develop and test wind power technology for use on Mars, Ames Research Center turned to Northern Power Systems (NPS), based in Barre, Vermont. Ames awarded NPS an SBIR contract so the company could enhance their turbineÆs function. Today, over 200 NASA-derived Northern Power 100s are in operation on Earth and have reduced carbon emissions by 50,000 tons annually.
Numerical Simulations of a Roof-Top Wind Turbine
Unsteady numerical simulations of a high efficiency roof-top wind turbine have been performed. The wind turbine cross section design was based on geometrical optimization study of Rahai and Hefazi for increasing contributions of the lift force to the torque, resulting in significant improvements in the performance of a vertical axis wind turbine. The wind turbine was 30 cm in diameter and 75 cm length, with 45 cm diameter end-plates, placed in the spanwise direction above a 26 degree slanted roof at 20 percent from the roof's highest elevation and one turbine diameter away from the roof surface. The approaching wind velocity was 30 m/sec and the wind turbine RPM was 233. Results indicate nearly 20 percent improvements in the power output, when compared with the corresponding results for a free standing wind turbine. However, the wind turbine operation imposes oscillatory stress on the roof, which could results in structural vibration and damage and noise generation.
Moayedian, Shahab; Rahai, Hamid
Effects of Wind Turbine Farms on Air Defence Radars.
The UK Government supports the introduction of wind turbine farms as part of its alternative energy strategy but existing Ministry of Defense (MoD) Guidelines restrict planning consent for wind turbine farms within 60% of maximum instrumented range (inter...
Power Performance Test Report for the SWIFT Wind Turbine.
This report summarizes the results of a power performance test that NREL conducted on the SWIFT wind turbine. This test was conducted in accordance with the International Electrotechnical Commission's (IEC) standard, Wind Turbine Generator Systems Part 12...
I. Mendoza J. Hur
Magnus wind turbines as an alternative to the blade ones
Experimental and calculated data on a wind turbine equipped with rotating cylinders instead of traditional blades are reported. Optimal parameters and the corresponding operational characteristics of the windwheel are given in comparison with those of the blade wind turbines.
Bychkov, N. M.; Dovgal, A. V.; Kozlov, V. V.
Safety, reliability and condition monitoring of wind turbines. Proceedings.
During recent years the number of wind turbines installed in the UK has grown rapidly. Operators of wind turbines require a reliable performance with minimum outage times in order to ensure commercial viability. Safety and reliability are clearly of param...
G. M. Smith B. R. Clayton
Methods of making wind turbine rotor blades
A method of manufacturing a root portion of a wind turbine blade includes, in an exemplary embodiment, providing an outer layer of reinforcing fibers including at least two woven mats of reinforcing fibers, providing an inner layer of reinforcing fibers including at least two woven mats of reinforcing fibers, and positioning at least two bands of reinforcing fibers between the inner and outer layers, with each band of reinforcing fibers including at least two woven mats of reinforcing fibers. The method further includes positioning a mat of randomly arranged reinforcing fibers between each pair of adjacent bands of reinforcing fibers, introducing a polymeric resin into the root potion of the wind turbine blade, infusing the resin through the outer layer, the inner layer, each band of reinforcing fibers, and each mat of random reinforcing fibers, and curing the resin to form the root portion of the wind turbine blade.
Livingston, Jamie T. (Pensacola, FL); Burke, Arthur H. E. (Gulf Breeze, FL); Bakhuis, Jan Willem (Nijverdal, NL); Van Breugel, Sjef (Enschede, NL); Billen, Andrew (Daarlerveen, NL)
The NASA Lewis large wind turbine program
The program is directed toward development of the technology for safe, reliable, environmentally acceptable large wind turbines that have the potential to generate a significant amount of electricity at costs competitive with conventional electric generation systems. In addition, these large wind turbines must be fully compatible with electric utility operations and interface requirements. Advances are made by gaining a better understanding of the system design drivers, improvements in the analytical design tools, verification of design methods with operating field data, and the incorporation of new technology and innovative designs. An overview of the program activities is presented and includes results from the first and second generation field machines (Mod-OA, -1, and -2), the design phase of the third generation wind turbine (Mod-5) and the advanced technology projects. Also included is the status of the Department of Interior WTS-4 machine.
Thomas, R. L.; Baldwin, D. H.
Wind Speed Estimation Based Sensorless Output Maximization Control for a Wind Turbine Driving a DFIG
This paper proposes a wind speed estimation based sensorless maximum wind power tracking control for variable-speed wind turbine generators (WTGs). A specific design of the proposed control algorithm for a wind turbine equipped with a doubly fed induction generator (DFIG) is presented. The aerodynamic characteristics of the wind turbine are approximated by a Gaussian radial basis function network based nonlinear
Wei Qiao; Wei Zhou; Jos╔ M. Aller; Ronald G. Harley
Advanced wind turbine design studies: Advanced conceptual study
In conjunction with the US Department of Energy and the National Renewable Energy Laboratory's Advanced Wind Turbine Program, the Atlantic Orient Corporation developed preliminary designs for the next generation of wind turbines. These 50 kW and 350 kW turbines are based upon the concept of simplicity. By adhering to a design philosophy that emphasizes simplicity, we project that these turbines
P. Hughes; R. Sherwin
TurbSim: Reliability-based wind turbine simulator
Wind turbine farms are an effective generator of electricity in windy parts of the world, with prices progressing to levels competitive with other sources. Choosing the correct turbine for a given installation requires significant engineering and the current trend leads towards groups of large horizontal axis turbines. Unfortunately, large wind turbines have to contend with large forces and other sources
Joseph T. Foley; Timothy G. Gutowski
Battery Voltage Stability Effects on Small Wind Turbine Energy Capture.
Previous papers on small wind turbines have shown that the ratio of battery capacity to wind capacity (known as battery-wind capacity ratio) for small wind systems with battery storage has an important effect on wind turbine energy output. Data analysis f...
D. Corbus C. Newcomb E. I. Baring-Gould S. Friedly
Shear and Turbulence Estimates for Calculation of Wind Turbine Loads and Responses Under Hurricane Strength Winds
Schwartz et al. (2010) recently reported that the total gross energy-generating offshore wind resource in the United States in waters less than 30m deep is approximately 1000 GW. Estimated offshore generating capacity is thus equivalent to the current generating capacity in the United States. Offshore wind power can therefore play important role in electricity production in the United States. However, most of this resource is located along the East Coast of the United States and in the Gulf of Mexico, areas frequently affected by tropical cyclones including hurricanes. Hurricane strength winds, associated shear and turbulence can affect performance and structural integrity of wind turbines. In a recent study Rose et al. (2012) attempted to estimate the risk to offshore wind turbines from hurricane strength winds over a lifetime of a wind farm (i.e. 20 years). According to Rose et al. turbine tower buckling has been observed in typhoons. They concluded that there is "substantial risk that Category 3 and higher hurricanes can destroy half or more of the turbines at some locations." More robust designs including appropriate controls can mitigate the risk of wind turbine damage. To develop such designs good estimates of turbine loads under hurricane strength winds are essential. We use output from a large-eddy simulation of a hurricane to estimate shear and turbulence intensity over first couple of hundred meters above sea surface. We compute power spectra of three velocity components at several distances from the eye of the hurricane. Based on these spectra analytical spectral forms are developed and included in TurbSim, a stochastic inflow turbulence code developed by the National Renewable Energy Laboratory (NREL, http://wind.nrel.gov/designcodes/preprocessors/turbsim/). TurbSim provides a numerical simulation including bursts of coherent turbulence associated with organized turbulent structures. It can generate realistic flow conditions that an operating turbine would encounter under hurricane strength winds. These flow fields can be used to estimate wind turbine loads and responses with AeroDyn (http://wind.nrel.gov/designcodes/simulators/aerodyn/) and FAST (http://wind.nrel.gov/designcodes/simulators/fast/) codes also developed by NREL.
Kosovic, B.; Bryan, G. H.; Haupt, S. E.
Structural dynamic analysis of wind turbine systems
The paper presents an overview of the dynamic analysis of horizontal axis wind turbines. The major emphasis of the paper is the review of current analysis methods and the comparison of results with experimental data. The current capabilities for predicting turbine system natural frequencies are discussed and the design implications of frequency placement are reviewed. The prediction of cyclic loads, using the dynamic analysis computer codes, is examined and comparisons are made between the code predictions and field test data. Finally, the dynamic analysis needs for advanced turbine systems are considered.
Thresher, R. W.
Investigation on wind turbine wakes: wind tunnel tests and field experiments with LIDARs
An investigation on the interaction between atmospheric boundary layer flow and wind turbines is carried out with wind tunnel and LIDAR measurements. The former were carried out using hot-wire anemometry and multi-hole pressure probes in the wake of a three-bladed miniature wind turbine. The wind turbine wake is characterized by a strong velocity defect in the proximity of the rotor, and its recovery is found to depend on the characteristics of the incoming atmospheric boundary layer (mean velocity and turbulence intensity profiles). Field experiments were performed using three wind LIDARs. Bi-dimensional scans are performed in order to analyse the wake wind field with different atmospheric boundary layer conditions. Furthermore, simultaneous measurements with two or three LIDARs allow the reconstruction of multi-component velocity fields. Both LIDAR and wind tunnel measurements highlight an increased turbulence level at the wake boundary for heights comparable to the top-tip of the blades; this flow feature can produce dangerous fatigue loads on following wind turbines.
Valerio Iungo, Giacomo; Wu, Ting; C÷effķ, Juliette; Portķ-Agel, Fernando
The Wind Turbine Drivetrain Test Facility (WTDTF) is a state-of-the-art industrial facility used for testing wind turbine drivetrains and generators. Large power output wind turbines are primarily installed for off-shore wind power generation. The facility includes two test bays: one to accommodate turbine nacelles up to 7.5 MW and one for nacelles up to 15 MW. For each test bay,
Wind shear climatology for large wind turbine generators
Climatological wind shear analyses relevant to the design and operation of multimegawatt wind turbines are provided. Insight is provided for relating the wind experienced by a rotating blade in a shear flow to the analysis results. A simple analysis of the wind experienced by a rotating blade for three types of wind shear profiles under steady-state conditions is presented in graphical form. Comparisons of the magnitude and frequency of the variations in 1) the wind sensed by a single blade element, 2) the sum, and 3) the difference of the winds sensed by opposite blade elements show strong sensitivity to profile shape. These three items represent forcing functions that can be related to 1) flatwise bending moment, 2) torque on the shaft, and 3) teeter angle. A computer model was constructed to simulate rotational sampling of 10-s sampled winds from a tall tower for three different types of large wind turbines. Time series produced by the model indicated that the forcing functions on a rotating blade vary according to the shear profile encountered during each revolution as opposed to a profile derived from average wind conditions, e.g., hourly average winds. An analysis scheme was developed to establish a climatology of wind shear profiles derived from 10-s sampled winds and hourly average winds measured over a one-year period at several levels on a tall tower. Because of the sensitivity of the forcing function variability to profile shape, the analyses performed and presented are in the form of joint frequency distributions of velocity differences of the the top-to-hub versus the hub-to-bottom portion of disks of rotation for the three turbine configurations.
Elliott, D.L.; Wendell, L.L.; Heflick, S.K.
Aileron controls for wind turbine applications
Horizontal axis wind turbines which utilize partial or full variable blade pitch to regulate rotor speed were examined. The weight and costs of these systems indicated a need for alternate methods of rotor control. Aileron control is an alternative which has potential to meet this need. Aileron control rotors were tested on the Mod-O wind turbine to determine their power regulation and shutdown characteristics. Test results for a 20 and 38% chord aileron control rotor are presented. Test is shown that aileron control is a viable method for safety for safely controlling rotor speed, following a loss of general load.
Miller, D. R.; Putoff, R. L.
Linearized model for wind turbines in yaw
The analysis of rigid hut, three bladed horizontal axis, axisymmetric wind turbines in yaw is made using a linearized, four degree of freedom model. The linearized equations of motion of rotor and nacelle are developed using quasi-steady blade element theory and Lagrange's equations. The yaw behavior of the system is studied from coefficients of the equations of motion. Analytical results for two wind turbines are presented and studied. Sensitivity study of the terms in the yaw stiffness coefficient is made. Two FORTRAN computer programs are developed to compute the numerical values of coefficients of the equations of motion.
Chaiyapinunt, S.
Aeroelastic simulation of wind turbine blades
\\u000a The aim of this chapter is to compute dynamic stresses acting on wind turbine blades. These stresses are essential in predicting\\u000a fatigue of the rotor.\\u000a \\u000a \\u000a The turbine rotor is exposed to wind loading of a cyclic nature, making it vulnerable to cumulative fatigue damage.\\u000a \\u000a \\u000a The approach used in this chapter is based on the analysis of the blade movement, by
Z. L. Mahri; M. S. Rouabah; Z. Said
Mod-2 wind turbine field operations experience
The Mod-2 wind turbine is now in a 2-year research/experimental operations phase which offers a unique opportunity to study the effects of single and multiple wind turbines interacting with each other, the power grid, and the environment. This paper addresses the field operations and research testing experienced at the Mod-2 Cluster Goodnoe Hills Research Test Site near Goldendale, WA. Field operation, both routine and nonroutine, are discussed as well as the role of the participating utility. Technical areas discussed pertain to system performance and loads. Specific research tests relating to acoustics, TV interference, and wake effects are also discussed.
Gordon, L. H.
Dynamic loads must be predicted accurately in order to estimate the fatigue life of wind turbines operating in turbulent environments. Dynamic stall contributes to increased dynamic loads during normal operation of all types of horizontal-axis wind turbine (HAWTs). This report illustrates how dynamic stall varies throughout the blade span of a 10 m HAWT during yawed and unyawed operating conditions. Lift, drag, and pitching moment coefficients during dynamics stall are discussed. Resulting dynamic loads are presented, and the effects of dynamic stall on yaw loads are demonstrated using a yaw loads dynamic analysis (YAWDYN). 12 refs., 22 figs., 1 tab.
Butterfield, C.P.; Simms, D.; Scott, G. (National Renewable Energy Lab., Golden, CO (United States)); Hansen, A.C. (Utah Univ., Salt Lake City, UT (United States))
Experimental and Theoretical Investigation of Micro-pitting in Wind Turbine Gears and Bearings. Covering Period January 1, 2010 to December 31, 2011.
In this research study, the micro-pitting related contact failures of wind turbine gearbox components were investigated both experimentally and theoretically. On the experimental side, a twin-disk type test machine was used to simulate wind turbine transm...
A. Kahraman
Assessment of fatigue life for small composite wind turbine blades
The present design and assessment of fatigue life for the small composite wind turbine blades (SCWTBs) can be certified by IEC 61400-2 ōWind Turbines - Part2: Design requirements of small wind turbinesö. The paper will establish an analytical method on the fatigue life analysis of SCWTBs. Using the Microsoft Office EXCEL to calculate the maximum stress, minimum stress and stress
Jia-Hroung Wu
Study on Lightning Protection Methods for Wind Turbine Blades
Lightning protection measures for wind turbines are becoming important as the use of wind turbines is increasing rapidly along with its capacity and height. In order to understand the manner of lightning attachment to wind turbine blades, experiments with various types of blade samples were conducted. Experimental studies revealed following issues. Regarding a non-conductive blade sample, the 50% flashover voltage
Takehiro Naka; Nilesh J. Vasa; Shigeru Yokoyama; Atsushi Wada; Akira Asakawa; Hideki Honda; Kazuhisa Tsutsumi; Shinji Arinaga
Transient grounding characteristics of wind turbine with counterpoise
Installations of wind turbine generator systems are noteworthy examples of eco-friendly energy generation. Because larger-scale facilities and increased electrical capacity can be realized by increasing the number of turbines, wind energy can be utilized more efficiently than other clean energy sources. However, the number of lightning strikes has increased with the popularization of wind turbine generator systems because of their
Junichi Niihara; Akihiro Ametani; Kazuo Yamamoto
Initialization of wind turbine models in power system dynamics simulations
As a result of increasing environmental concern, increasing amounts of electricity are generated from renewable sources. One way of generating electricity from renewable sources is to use wind turbines. A tendency to erect more wind turbines can be observed. As a result of this, in the near future wind turbines may start to influence the behavior of electrical power systems.
J. G. Slootweg; H. Polinder; W. L. Kling
Flicker emission of wind turbines during continuous operation
This paper presents an analysis and the modeling of the flicker emission of wind turbines. Measurements compared with international standards are discussed. The paper concentrates on the theoretical aspects of the flicker algorithm, wind turbine characteristics and the generation of flicker during continuous operation of wind turbines
┼ke Larsson
Modeling of wind turbines for power system studies
In this paper, the modeling of wind turbines for power system studies is investigated. Complexities of various parts of a wind turbine model, such as aerodynamic conversion, drive train, and generator representation, are analyzed. The results are verified by field measurements made on a stall-regulated fixed-speed wind turbine. The modeling focuses on deriving a representation that is suitable for use
Tomas Petru; Torbj÷rn Thiringer
Voltage Sag Impact on Wind Turbine Tower Vibration
In order to study the voltage sag impact on mechanical vibration of wind turbine structure a detailed model that considers all three electrical, mechanical and aerodynamic aspects of the wind turbine must be considered. A drawback of many works in the area of wind turbine simulation is that either a very simple mechanical model is used with a detailed electrical
Roohollah Fadaeinedjad; Gerry Moschopoulos; Mehrdad Moallem
Radar-cross-section reduction of wind turbines. part 1
In recent years, increasing deployment of large wind-turbine farms has become an issue of growing concern for the radar community. The large radar cross section (RCS) presented by wind turbines interferes with radar operation, and the Doppler shift caused by blade rotation causes problems identifying and tracking moving targets. Each new wind-turbine farm installation must be carefully evaluated for potential
Billy C. Brock; Hung Loui; Jacob J. McDonald; Joshua A. Paquette; David A. Calkins; William K. Miller; Steven E. Allen; Paul Gilbert Clem; Ward E. Patitz
Control system of a MW-class wind turbine
This dissertation is on control system for MW-class wind turbine. The basic control structure is on the performance of wind turbine and is a control system tracked power curve. To track the power curve, we discuss the control method for variable speed variable pitch that is used for torque control and pitch control. Furthermore, the MW-class wind turbine is a
Jeonggi Kim; Janghwan Cho; Hansoon Choi; Yoonsu Nam
Interaction between Electrical Grid Phenomena and the Wind Turbine's Behaviour
The paper gives an overview of fundamental electrical aspects that are relevant for wind turbine designers or users. The notions 'three phase systems', 'active and reactive power', 'short-circuit power', 'ancillary services' and 'power quality' are briefly reviewed. The three most important generator types for wind turbines are reviewed. The block model approach for simulating wind turbines in power systems is
J. Soens; J. Driesen; R. Belmans
Wind Turbine Generator System Power Quality Test Report for the Gaia Wind 11-kW Wind Turbine
This report details the power quality test on the Gaia Wind 11-kW Wind Turbine as part of the U.S. Department of Energy's Independent Testing Project. In total five turbines are being tested as part of the project. Power quality testing is one of up to five test that may be performed on the turbines including power performance, safety and function, noise, and duration tests. The results of the testing provide manufacturers with reports that may be used for small wind turbine certification.
Curtis, A.; Gevorgian, V.
Wind Turbine Generator System Duration Test Report for the ARE 442 Wind Turbine
This test is being conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers of wind energy expansion by providing independent testing results for small turbines. In total, four turbines are being tested at the NWTC as a part of this project. Duration testing is one of up to 5 tests that may be performed on the turbines, including power performance, safety and function, noise, and power quality tests. The results of the testing provide manufacturers with reports that may be used for small wind turbine certification. The test equipment includes a grid connected ARE 442 wind turbine mounted on a 30.5 meter (100 ft) lattice tower manufactured by Abundant Renewable Energy. The system was installed by the NWTC Site Operations group with guidance and assistance from Abundant Renewable Energy.
Flow separation on wind turbines blades
In the year 2000, 15GW of wind power was installed throughout the world, producing 100PJ\\u000aof energy annually. This contributes to the total electricity demand by only 0.2%. Both the\\u000ainstalled power and the generated energy are increasing by 30% per year world-wide. If the\\u000aairflow over wind turbine blades could be controlled fully, the generation efficiency and thus\\u000athe
G. P. Corten
This article describes the development of the tallest and most powerful windmill of its kind in the U.S. Known as a Vertical Axis Wind Turbine (VAWT), the machine is meant for testing new concepts in vertical axis turbine design. As part of its overall testing program, the turbine will supply electricity to automated water pumps used in irrigation research at the Research Laboratory in Bushland, Texas. Excess power will go to the Southwestern Public Service Company for the area power system.
Miller, S.
Root region airfoil for wind turbine
A thick airfoil for the root region of the blade of a wind turbine. The airfoil has a thickness in a range from 24%-26% and a Reynolds number in a range from 1,000,000 to 1,800,000. The airfoil has a maximum lift coefficient of 1.4-1.6 that has minimum sensitivity to roughness effects.
Structural health monitoring of wind turbine blades
As electric utility wind turbines increase in size, and correspondingly, increase in initial capital investment cost, there is an increasing need to monitor the health of the structure. Acquiring an early indication of structural or mechanical problems allows operators to better plan for maintenance, possibly operate the machine in a de-rated condition rather than taking the unit off-line, or in
Mark A. Rumsey; Joshua A. Paquette
Fatigue of fiberglass wind turbine blade materials
Fatigue behavior for a variety of generic materials used in wind turbine blades was explored. Coupon testing was carried out under constant amplitude tensile fatigue loading to beyond 10(exp 7) cycles for most materials. Unidirectional materials performed close to expectations despite fiber misalignment. Materials with triaxial (0\\/plus or minus 45) reinforcement showed greater fatigue sensitivity than expected, but lifetime trends
J. F. Mandell; R. M. Reed; D. D. Samborsky
Panel resonant behavior of wind turbine blades
The principal design drivers in the certification of wind turbine blades are ultimate strength, fatigue resistance, adequate tip-tower clearance, and buckling resistance. Buckling resistance is typically strongly correlated to both ultimate strength and fatigue resistance. A composite shell with spar caps forms the airfoil shape of a blade and reinforcing shear webs are placed inside the blade to stiffen the
Joshua A. Paquette; Daniel Todd Griffith
Wind turbine generator with improved operating subassemblies
A wind turbine includes a yaw spring return assembly to return the nacelle from a position to which it has been rotated by yawing forces, thus preventing excessive twisting of the power cables and control cables. It also includes negative coning restrainers to limit the bending of the flexible arms of the rotor towards the tower, and stop means on
Cheney Jr
Wind turbine speed control by automatic yawing
A yaw dynamics analysis was developed for a two-bladed horizontal axis wind turbine with passive cyclic pitch variation achieved by letting the blade pair freely oscillate about a common axis with which the blades formed a small prelag angle. This type of rotor was found capable of high yaw rates without imposing vibratory hub moments and without producing noticeable flapping
Kurt H. Hohenemser; Andrew H. P. Swift
Full Life Wind Turbine Gearbox Lubricating Fluids
Industrial gear box lubricants typically are hydrocarbon based mineral oils with considerable amounts of additives to overcome the lack of base fluid properties like wear protection, oxidation stability, load carrying capacity, low temperature solidification and drop of viscosity at higher temperatures. For today's wind turbine gearboxes, the requirements are more severe and synthetic hydrocarbon oils are used to improve on
Glenn A. Lutz; Manfred Jungk; Jonathan J. Bryant; Rebecca S. Lauer; Anthony Chobot; Tyler Mayer; Shane Palmer; Robert E. Kauffman
Power converter for wind turbine application
Variable speed wind turbines are known to provide more effective power capture than their fixed-speed counterparts. To generate electrical power over a wide range of speeds, induction generators have been shown to be superior in many ways to DC generators: efficiency, maintainability, power density, etc. Unfortunately, loads are typically fixed-frequency. A power electronic converter enables efficient conversion of the variable
Herbert L. Hess; Noor A. Abdul Melek; E. Muljadi
Self-regulating composite bearingless wind turbine
The Composite Bearingless Rotor (CBR) concept has been shown to have characteristics ideally suited for wind turbine applications. Originally developed for helicopters to reduce weight, costs, and complexity, the CBR eliminates blade bearings and hinges through the utilization of the unique structural characteristics of uniaxial composite materials. This rotor concept was further developed under an ERDA contract to provide a
M. C. Cheney; P. A. M. Spierings
Latest wind turbine designs bolster industry confidence
This article describes a new generation of turbine designs, along with government incentives and support, that are prompting windpower projects with projected performance and economics that seem to satisfy the financiers. Wind-energy powerplants have been struggling to enter that promised land of commercially acceptable electric generation options for almost a decade. Ironically, some environmental groups, once ardent supporters of the
A Gust Model for Wind Turbine Design
A new method, so called constrained stochastic simulation, has been developed in order to generate extreme gust time series, to be used to calculate the extreme loading of wind turbines. A constrained simulation corresponds to the addition, in a special manner, of turbulence and a deterministic part (which resembles the auto correlation function of turbulence). The stochastic gusts produced in
Wim Bierbooms
Optimization of wind turbine design for SWECS
Current research to optimize wind turbine designs centers on the most important parameter, the useful lifetime of the rotor assembly. A rotor design which promises to extend the lifetime of the full rotor assembly is discussed. That design improvement includes the integration of a teetered rotor hub and a delta-3 angle. This design concept was proven in helicopter and rotor
P. J. Bryant
Wooden wind turbine blade manufacturing process
A wooden wind turbine blade is formed by laminating wood veneer in a compression mold having the exact curvature needed for one side of the blade, following which the other side of the blade is ground flat along its length but twisted with respect to the blade axis.
Coleman, Clint (Warren, VT)
Structural Health Monitoring of Wind Turbine Blades
Dynamic stall model for wind turbine airfoils
A model is presented for aerodynamic lift of wind turbine profiles under dynamic stall. The model combines memory delay effects under attached flow with reduced lift due to flow separation under dynamic stall conditions. The model is based on a backbone curve in the form of the static lift as a function of the angle of attack. The static lift
J. W. Larsen; S. R. K. Nielsen; S. Krenk
Infrasound from Wind Turbines Could Affect Humans
ERIC Educational Resources Information Center
Wind turbines generate low-frequency sounds that affect the ear. The ear is superficially similar to a microphone, converting mechanical sound waves into electrical signals, but does this by complex physiologic processes. Serious misconceptions about low-frequency sound and the ear have resulted from a failure to consider in detail how the earģ
Salt, Alec N.; Kaltenbach, James A.
Wind Turbine Tribology Seminar - A Recap
Tribology is the science and engineering of interacting surfaces in relative motion. It includes the study and application of the principles of friction, lubrication, and wear. It is an important phenomenon that not only impacts the design and operation of wind turbine gearboxes, but also their subsequent maintenance requirements and overall reliability. With the major growth and increasing dependency on
R. Errichello; S. Sheng; J. Keller; A. Greco
Suction caisson foundations are being investigated for oshore wind turbine applications. The research programme includes laboratory testing, larger scale field testing and theoretical modelling. This paper concentrates on the experi- mental results obtained in combined loading tests on monopod caissons. Results obtained from monotonic and cyclic tests on caissons installed either by pushing or by suction are presented and interpreted.
Felipe A. Villalobos; Guy T. Houlsby; Byron W. Byrne
This paper presents the wind turbine airfoil development at Ris°. The design method is described together with our target characteristics for wind turbine airfoils. The use of the CFD code Ellipsys2D for prediction of final target characteristics is described together with the VELUX wind tunnel testing setup. Three airfoil families were developed; Ris°-A1, Ris°-P and Ris°-B1. The Ris°-A1 airfoil family was developed for rotors of 600 kW and larger. Wind tunnel testing and field testing showed that this airfoil family is well suited for stall and active stall control. However, sensitivity to roughness was higher than expected. Field tests of a 600 kW active stall wind turbine showed an estimated reduction in blade fatigue loading of up to 15% at the same annual energy yield and at the same time reduced blade weight and blade solidity. The Ris°-P airfoils were developed to replace the Ris°-A1 airfoils for use on pitch controlled wind turbines. Improved design objectives should reduce the sensitivity to roughness, but measurements are not yet available. The Ris°-B1 airfoil family was developed for variable speed operation with pitch control of large megawatt sized rotors. Wind tunnel testing verified the high maximum lift for these airfoils, and the airfoils were found to be very insensitive to leading edge roughness. Performance with vortex generators and Gurney flaps in combination was found to be attractive for the blade root part. Field testing of a 1.5 MW rotor is in progress. Copyright
Fuglsang, Peter; Bak, Christian
Stationary turbine component with laminated skin
A stationary turbine engine component, such as a turbine vane, includes a internal spar and an external skin. The internal spar is made of a plurality of spar laminates, and the external skin is made of a plurality of skin laminates. The plurality of skin laminates interlockingly engage the plurality of spar laminates such that the external skin is located and held in place. This arrangement allows alternative high temperature materials to be used on turbine engine components in areas where their properties are needed without having to make the entire component out of such material. Thus, the manufacturing difficulties associated with making an entire component of such a material and the attendant high costs are avoided. The skin laminates can be made of advanced generation single crystal superalloys, intermetallics and refractory alloys.
James, Allister W. (Orlando, FL)
Aggregation of doubly fed induction generators wind turbines under different incoming wind speeds
The increasing wind power penetration in power systems requires the development of adequate wind farms models to be included in power system simulation software in order to represent the behavior of wind farms in power systems. The modeling of wind farms with high number of wind turbines requires the development of a high order model if all the wind turbines
L. M. Fernandez; C. A. Garcia; F. Jurado; J. R. Saenz
The UAE wind turbine performance prediction using wind tunnel airfoil data
It's vitally important for wind turbine aerodynamic performance predictions to design and optimize wind turbines. In view of the BEM method's fast speed and widespread use, this paper applies WT_Perf software of NREL to predict the performance on a NREL Phase VI upwind wind turbine. Measurements from the Phase VI of the NREL\\/NASA Ames wind tunnel test were used for
Chenkai Zhang; Jun Hu
The effect of wind shear and pitch control delaying on wind turbine blade loading
The loading analysis model of wind turbine blade is established according to strip theory of rotor aerodynamics. For a 1.5MW wind turbine, the force distribution on blade at rated wind speed and the moments of the blade root in various work case are dealt with by this model. The Effect of pitch control delaying on the loads of wind turbine
Jie Fu; Hui-ling Zhang; Bin He; Qin-shan Fan
Review of offshore wind turbine failures and fault prognostic methods
Wind electricity is a highly promoted energy source all around the world. The number of offshore wind farms, increases gradually because of the high capability of power generation. However, the cost of manufacturing, logistics, installation, grid control and maintenance of offshore wind turbine is high. According to the Condition Monitoring of Offshore Wind Turbine (CONMOW) report of Energy Research Centre
Bill Chun Piu Lau; Eden Wai Man Ma; Michael Pecht
Electrical generation using a vertical-axis wind turbine
Traditionally, windmills have been of the propeller or multiblade types, both of which have their rotational axis parallel to the flow of the wind. A vertical-axis wind turbine has its rotational axis perpendicular to the flow of wind and requires no orientation to keep the rotor in the windstream. The vertical-axis wind turbine operates on the same principle as an
Performance characteristics of aerodynamically optimum turbines for wind energy generators
This paper presents a brief discussion of the aerodynamic methodology for wind energy generator turbines, an approach to the design of aerodynamically optimum wind turbines covering a broad range of design parameters, some insight on the effect on performance of nonoptimum blade shapes which may represent lower fabrication costs, the annual wind turbine energy for a family of optimum wind turbines, and areas of needed research. On the basis of the investigation, it is concluded that optimum wind turbines show high performance over a wide range of design velocity ratios; that structural requirements impose constraints on blade geometry; that variable pitch wind turbines provide excellent power regulation and that annual energy output is insensitive to design rpm and solidity of optimum wind turbines.
Rohrbach, C.; Worobel, R.
Duration Test Report for the Viryd CS8 Wind Turbine
This report summarizes the results of a duration noise test that the National Renewable Energy Laboratory (NREL) conducted on the Viryd CS8 wind turbine. This test was conducted in accordance with Clause 9.4 of the International Electrotechnical Commission's (IEC) standard, Wind turbines - Part 2: Design requirements for small wind turbines, IEC 61400-2 Ed. 2.0:2006-03. NREL researchers evaluated the turbine based on structural integrity and material degradation, quality of environmental protection, and dynamic behavior.
Roadman, J.; Murphy, M.; van Dam, J.
Selected wind tunnel test results for the Darrieus wind turbine
Five blade configurations of a 2-m-diam Darrieus wind turbine have been tested in the Vought Corporation 4.6- x 6.1-m (15- x 20-ft) Low-Speed Wind Tunnel. Rotor solidity, Reynolds number, and freestream velocities tested were in the following ranges: solidity, 13 to 30%; Reynolds number, 1 to 3 x 10ŌüĄ; freestream velocity, 7 to 11 m\\/s. The airfoil selection for all
B. F. Blackwell; R. E. Sheldahl
Five blade configurations of a 2-m-diam Darrieus wind turbine have been tested in a low-speed wind tunnel. Rotor solidity, Reynolds number, and free-stream velocities tested were in the following ranges: solidity, 13-30%; Reynolds number, 100,000-300,000; free-stream velocity, 7-11 m\\/s. The airfoil selection for all configurations was NACA 0012. The parameters measured were rotor torque, rotor rotational speed, and tunnel conditions.
Augmented Adaptive Control of a Wind Turbine in the Presence of Structural Modes
Wind turbines operate in highly turbulent environments resulting in aerodynamic loads that can easily excite turbine structural modes, potentially causing component fatigue and failure. Two key technology drivers for turbine manufacturers are increasing turbine up time and reducing maintenance costs. Since the trend in wind turbine design is towards larger, more flexible turbines with lower frequency structural modes, manufacturers will want to develop methods to operate in the presence of these modes. Accurate models of the dynamic characteristics of new wind turbines are often not available due to the complexity and expense of the modeling task, making wind turbines ideally suited to adaptive control. In this paper, we develop theory for adaptive control with rejection of disturbances in the presence of modes that inhibit the controller. We use this method to design an adaptive collective pitch controller for a high-fidelity simulation of a utility-scale, variable-speed wind turbine operating in Region 3. The objective of the adaptive pitch controller is to regulate generator speed, accommodate wind gusts, and reduce the interference of certain structural modes in feedback. The control objective is accomplished by collectively pitching the turbine blades. The adaptive pitch controller for Region 3 is compared in simulations with a baseline classical Proportional Integrator (PI) collective pitch controller.
Frost, Susan A.; Balas, Mark J.; Wright, Alan D.
Fatigue life variability and reliability analysis of a wind turbine blade.
Wind turbines must withstand harsh environments that induce many stress cycles into their components. A numerical analysis package is used to illustrate the sobering variability in predicted fatigue life with relatively small changes in inputs. The variab...
P. S. Veers H. J. Sutherland T. D. Ashwill
Control can improve energy capture and reduce dynamic loads in wind turbines. In the 1970s and 1980s wind turbines used classical control designs to regulate power and speed. The methods used, however, were not always successful. These systems often had bandwidths large enough to destabilize low-damped flexible modes leading to high dynamic load fatigue failures. Modern turbines are larger, mounted on taller towers, and are more dynamically active than their predecessors. Control systems to regulate turbine power and maintain stable closed-loop behavior in the presence of turbulent wind inflow will be critical for these designs. New advanced control approaches and paradigms must account for low-damped flexible modes in order to reduce structural dynamic loading and achieve the 20--25 year operational life required of today's machines. This thesis applies modern state-space control design methods to a two-bladed teetering hub upwind machine located at the National Wind Technology Center. The design objective is to regulate turbine speed and enhance damping in several low-damped flexible modes of the turbine. Starting with simple control algorithms based on linear models, complexity is added incrementally until the desired performance is firmly established. The controls approach is based on the Disturbance Accommodating Control (DAC) method and provides accountability for wind-speed fluctuations. First, controls are designed using the single control input rotor collective pitch to stabilize the 1st drive-train torsion as well as the tower 1st fore-aft bending modes. Generator torque is then incorporated as an additional control input. This reduces some of the demand placed on the rotor collective pitch control system and enhances 1st drive train torsion mode damping. Individual blade pitch control is then used to attenuate wind disturbances having spatial variation over the rotor and effectively reduces blade flap deflections due to wind shear. Finally, results from these modern controls are compared to results from simpler classical controls in order to assess modern controller performance. These modern controls are shown to more effectively mitigate tower fore-aft motion, drive-train shaft torsion moments, and blade root flap bending moments when compared to the classical control approaches.
Wright, Alan Duane
Dynamic behavior of variable speed wind turbines under stochastic wind
It is recognized that the most important advantage of the variable speed wind turbines (VS WTs) over the conventional constant speed (CS) machines are the improved dynamic characteristics, resulting in the reduction of the drive train mechanical stresses and output power fluctuations. In this paper alternative configurations of the electrical part of a VS WT are considered, using a squirrel
S. A. Papathanassiou; M. P. Papadopoulos
NREL Small Wind Turbine Test Project: Mariah Power's Windspire Wind Turbine Test Chronology.
To help industry offer consumers more small wind turbine systems that are certified for safety and performance, the National Renewable Energy Laboratory (NREL) and the U.S. Department of Energy (DOE) launched a Small Wind Independent Testing project in 20...
A. Huskey T. Forsyth
A simple method of estimating wind turbine blade fatigue at potential wind turbine sites
This paper presents a technique of estimating blade fatigue damage at potential wind turbine sites. The cornerstone of this technique is a simple model for the blade's root flap bending moment. The model requires as input a simple set of wind measurements which may be obtained as part of a routine site characterization study. By using the model to simulate
J. C. Barnard; L. L. Wendell
This paper presents a technique of estimating blade fatigue damage at potential wind turbine sites. The cornerstone of this technique is a simple model for the blade`s root flap bending moment. The model requires as input a simple set of wind measurements that may be obtained as part of a routine site characterization study. By using the model to simulate
Lightning discharges produced by wind turbines
observations with a 3-D Lightning Mapping Array and high-speed video are presented and discussed. The first set of observations shows that under certain thunderstorm conditions, wind turbine blades can produce electric discharges at regular intervals of ~3 s in relation to its rotation, over periods of time that range from a few minutes up to hours. This periodic effect has not been observed in static towers indicating that the effect of rotation is playing a critical role. The repeated discharges can occur tens of kilometers away from electrically active thunderstorm areas and may or may not precede a fully developed upward lightning discharge from the turbine. Similar to rockets used for triggering lightning, the fast movement of the blade tip plays an important role on the initiation of the discharge. The movement of the rotor blades allows the tip to "runaway" from the generated corona charge. The second observation is an uncommon upward/downward flash triggered by a wind turbine. In that flash, a negative upward leader was initiated from a wind turbine without preceding lightning activity. The flash produced a negative cloud-to-ground stroke several kilometers from the initiation point. The third observation corresponds to a high-speed video record showing simultaneous upward positive leaders from a group of wind turbines triggered by a preceding intracloud flash. The fact that multiple leaders develop simultaneously indicates a poor shielding effect among them. All these observations provide some special features on the initiation of lightning by nonstatic and complex tall structures.
MontanyÓ, Joan; Velde, Oscar; Williams, Earle R.
Wind Forces and Peak Wind Pressure Distributions on Wind Turbine Nacelle
ABSRRACT In this paper, wind forces acting on a nacelle of wind turbine were measured in the wind tunnel experiments. In order to investigate the validity of application of surface mounted structure data on nacelle enclosure, two kinds of experiments, i.e. model set up on wind tunnel floor and the one apart from floor are carried out. Based on the
Hiroshi Nod; Kenji Shimada; Takeshi Ishihara
Wind power is a very promising source of environmentally safe, renewable, and the fast-growing energy source over the past several years. The blades of a wind turbine are considered to be an important component in wind turbine generator. Currently, bigger and more powerful wind blades are being built to increase the swept area of the turbine and extract more energy from the wind. Correspondingly, more capital cost is invested in manufacture and service. In order to reduce damage possibility and extend the wind turbine blades life, there are increasing demands for the inspection of wind turbine blades in the manufacturing factory and on site inspection. The regular inspections of wind turbine blades are done normally by using visual inspection and tapping test. To improve the safety of wind turbine blades, nondestructive testing technique using pulsed thermography is being investigated in this study. This technique utilized an active pulsed heating source that is applied on the outer surface of wind turbine blades, and an infrared camera to monitor the surface temperature distribution controlled by a computer. Reflective pulsed thermography was directly applied on several full scale wind blades, surface and subsurface defects, such as air bubbles, pin holes, edge bonding, etc. were clearly detected. Several specimens were intentionally manufactured to simulate the glue faults between supporting spars and glass fiber reinforced plastic (GFRP) shells with different thickness. Afterwards they were inspected by using pulsed thermography in laboratory. The current test results indicated that pulsed thermography has the potential for the detection of glue faults at least about 15mm thickness GFRP shell. It is shown that pulsed thermography maybe provide a powerful non-contacting technique for the inspection of wind turbine blades as well in the workshop just after the production or in the field that before and after installation of the wind blades and during reparation.
Tao, Ning; Zeng, Zhi; Feng, Lichun; Li, Xiaoli; Li, Yeshu; Zhang, Cunlin
Yaw dynamics of horizontal axis wind turbines
Numerous problems associated with yaw exist on free-yaw and yaw-driven wind turbines. Yaw-driven machines experience failures in the yaw drive mechanism due to excessive loads, while free-yaw machines experience high yaw rates and yaw misalignment problems. This report describes validation of a model for prediction of wind turbine yaw behavior. The model accounts for the coupled yaw and blade flapping motion of wind machines. The results from the model are compared to results from other analysis methods and to test data. Wind tunnel tests of a rigid-hub, two-bladed rotor, as well as full scale field test data from a rigid-hub, three-bladed turbine are used as the comparison cases in this report. The model predictions show good qualitative agreement with test data, but the magnitudes of predicted yaw moments are in error for some comparison cases. Future work will involve a more in-depth comparison of model results to comprehensive machine test data. Refinements will be made to the analytical model in order to improve correlations between theory and experiment.
Hansen, A.; Xudong, C.
Control of large wind turbine generators connected to utility networks
This is an investigation of the control requirements for variable pitch wind turbine generators connected to electric power systems. The requirements include operation in very small as well as very large power systems. Control systems are developed for wind turbines with synchronous, induction, and doubly fed generators. Simulation results are presented. It is shown how wind turbines and power system controls can be integrated. A clear distinction is made between fast control of turbine torque, which is a peculiarity of wind turbines, and slow control of electric power, which is a traditional power system requirement.
Hinrichsen, E. N.
Site matching of wind turbine generators: a case study
Site matching of wind turbine generators is investigated based on the appropriate selection of statistical models and means of wind speed data. The wind speed means are computed using arithmetic mean, root mean square and cubic mean cuberoot. Wind speed frequency distributions are modelled using Weibull and Rayleigh probability density functions. Wind speed data of an existing wind power station,
S. H. Jangamshetti; V. G. Rau
Wind and turbine characteristics needed for integration of wind turbine arrays into a utility system
Wind data and wind turbine generator (WTG) performance characteristics are often available in a form inconvenient for use by utility planners and engineers. The steps used by utility planners are summarized and the type of wind and WTG data needed for integration of WTG arrays suggested. These included long term yearly velocity averages for preliminary site feasibility, hourly velocities on a 'wind season' basis for more detailed economic analysis and for reliability studies, worst-case velocity profiles for gusts, and various minute-to-hourly velocity profiles for estimating the effect of longer-term wind fluctuations on utility operations. wind turbine data needed includes electrical properties of the generator, startup and shutdown characteristics, protection characteristics, pitch control response and control strategy, and electro-mechanical model for stability analysis.
Park, G. L.
The EPRI\\/DOE Utility Wind Turbine Performance Verification Program
In 1992, the Electric Power Research Institute (EPRI) and the US Department of Energy (DOE) initiated the Utility Wind Turbine Performance Verification Program (TVP). This paper provides an overview of the TVP, its purpose and goals, and the participating utility projects. Improved technology has significantly reduced the cost of energy from wind turbines since the early 1980s. In 1992, turbines
S. Calvert; P. Goldman; E. DeMeo; C. McGowin; B. Smith; K. Tromly
The Design of closed loop controllers for wind turbines
This article reviews the design of algorithms for wind turbine pitch control and also for generator torque control in the case of variable speed turbines. Some recent and possible future developments are discussed. Although pitch control is used primarily to limit power in high winds, it also has a significant effect on various loads. Particularly as turbines become larger, there
E. A. Bossanyi
Gearing ratios of a magnetic gear for wind turbines
The wind turbine industry is growing at an incredible rate as numerous governments demand an increase in renewable energy generation capacity. The great multitude of turbines on windfarms throughout the world range from ones which are controlled mechanically with gears to ones which are controlled with power electronics and no gears. A drivetrain for a wind turbine which eliminates the
Nicolas W. Frank; Hamid A. Toliyat
Wind shear for large wind turbine generators at selected tall tower sites
The objective of the study described in this report is to examine the nature of wind shear profiles and their variability over the height of large horizontal-axis wind turbines and to provide information on wind shear relevant to the design and opertion of large wind turbines. Wind turbine fatigue life and power quality are related through the forcing functions on the blade to the shapes of the wind shear profiles and their fluctuations over the disk of rotation.
Elliott, D.L.
Investigation on wind power potential on Hong Kong islandsŚan analysis of wind power and wind turbine characteristics
This paper discusses the potential for electricity generation on Hong Kong islands through an analysis of the local weather data and typical wind turbine characteristics. An optimum wind speed, uop, is proposed to choose an optimal type of wind turbine for different weather conditions. A simulation model has been established to describe the characteristics of a particular wind turbine. A
Lin Lu; Hongxing Yang; John Burnett
Braking System for Wind Turbines
Operating turbine stopped smoothly by fail-safe mechanism. Windturbine braking systems improved by system consisting of two large steel-alloy disks mounted on high-speed shaft of gear box, and brakepad assembly mounted on bracket fastened to top of gear box. Lever arms (with brake pads) actuated by spring-powered, pneumatic cylinders connected to these arms. Springs give specific spring-loading constant and exert predetermined load onto brake pads through lever arms. Pneumatic cylinders actuated positively to compress springs and disengage brake pads from disks. During power failure, brakes automatically lock onto disks, producing highly reliable, fail-safe stops. System doubles as stopping brake and "parking" brake.
Krysiak, J. E.; Webb, F. E.
Flicker Contribution of a Wind Power Plant with Single and Multiple Turbine Representations
In order to study the impact of a wind power plant on network power quality all electrical, mechanical and aerodynamic aspects of wind turbines must be studied. Moreover, the contribution of every wind turbine on the wind power plant should be considered. Representing a large wind power plant by a single wind turbine (WT) or a few wind turbines results
Roohollah Fadaeinedjad; Mehrdad Moallem; G. Moschopoulos; S. Bassan
Post Stall Airfoil Data for Wind Turbines: Wind Tunnel Test Results.
Wind turbine blades operate over a wide angle of attack range. Unlike aircraft, a wind turbine's angle of attack range extends deep into stall where the three dimensional performance characteristics of airfoils are not generally known. Peak power predicti...
C. Ostowari D. Naik
Survey of modelling methods for wind turbine wakes and wind farms
This article provides an overview and analysis of different wake-modelling methods which may be used as prediction and design tools for both wind turbines and wind farms. We also survey the available data concerning the measurement of wind magnitudes in both single wakes and wind farms, and of loading effects on wind turbines under single- and multiple-wake conditions. The relative
A. Crespo; J. Hernßndez; S. Frandsen
Wind Turbine Generator System Duration Test Report for the Gaia-Wind 11 kW Wind Turbine
This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers of wind energy expansion by providing independent testing results for small turbines. In total, five turbines are being tested at the National Renewable Energy Laboratory's (NRELs) National Wind Technology Center (NWTC) as a part of this project. Duration testing is one of up to five tests that may be performed on the turbines, including power performance, safety and function, noise, and power quality tests. The results of the testing will provide the manufacturers with reports that may be used for small wind turbine certification. The test equipment includes a Gaia-Wind 11 kW wind turbine mounted on an 18 m monopole tower. Gaia-Wind Ltd. manufactured the turbine in Denmark, although the company is based in Scotland. The system was installed by the NWTC Site Operations group with guidance and assistance from Gaia-Wind.
Estimation of turbulence level and scale for wind turbine applications
A simplified method is presented for estimating onsite turbulence variance within the wind turbine layer for horizontal wind speed. The method is based principally on estimating the probability distribution of wind speed and assigning a variance to each mean wind speed based on surface roughness estimates. The model is not proposed as an alternative to onsite measurement and analysis, but rather as an adjunct to such a program. A revision of the Kaimal neutral u-component spectrum is suggested to apply to the mix of the stabilities occurring during operational winds. Values of integral length scale calculated from data analysis are shown to contradict the length scale model implicit in turbulence power spectra. Also, these calculated values are shown to be extremely sensitive to the length of the time series and the detrending method used. The analysis and modeling are extended to the rotational frame of reference for a horizontal-axis wind turbine by modeling the ratios of harmonic spike variances (1P, 2P, etc.) in the rotational spectrum to the Eulerian turbulence variance. 15 refs., 11 figs., 3 tabs.
Powell, D.C.
Composite Materials for Wind Power Turbine Blades
Renewable energy resources, of which wind energy is prominent, are part of the solution to the global energy problem. Wind turbine and the rotorblade concepts are reviewed, and loadings by wind and gravity as important factors for the fatigue performance of the materials are considered. Wood and composites are discussed as candidates for rotorblades. The fibers and matrices for composites are described, and their high stiffness, low density, and good fatigue performance are emphasized. Manufacturing technologies for composites are presented and evaluated with respect to advantages, problems, and industrial potential. The important technologies of today are prepreg (pre-impregnated) technology and resin infusion technology. The mechanical properties of fiber composite materials are discussed, with a focus on fatigue performance. Damage and materials degradation during fatigue are described. Testing procedures for documentation of properties are reviewed, and fatigue loading histories are discussed, together with methods for data handling and statistical analysis of (large) amounts of test data. Future challenges for materials in the field of wind turbines are presented, with a focus on thermoplastic composites, new structural materials concepts, new structural design aspects, structural health monitoring, and the coming trends and markets for wind energy.
Br°ndsted, Povl; Lilholt, Hans; Lystrup, Aage
Effects of precipitation on wind turbine performance
This report examines the effects of precipitation on the performance of a wind turbine, with an airfoil section similar to that of the MOD-O (23000 series), at an operating wind farm. Earlier NASA research noted a performance degradation of up to 24 percent for the MOD-OA when precipitation occurred. The objective of this study was to collect sufficient data at a wind farm where rainfall occurs frequently so that the effect of precipitation could be discriminated from the effects of the turbulence that may be associated with rain. The rainfall rates were considerably lower than the rates of rainfall considered in the previous NASA study. The rainfall rates experienced at the wind farm are generally below 8mm/h and would usually fall under the light rain classification of the previous NASA study. For light rain conditions, the NASA report showed as high as an 18 percent decrease in machine performance. The study described here did not show a decrease in performance from light rain; rather an increase of approximately 3 percent was indicated. The 3 percent increase may be attributable to a reduction of blade roughness, rain effects on the anemometer, or a combination of the two. The general conclusion is drawn for this study: for the ESI-54 wind turbine studied, for rainfall rates generally less than 8mm/h, the rain has a beneficial effect on performance by slightly improving the aerodynamic properties (maintaining clean blades).
Walker, S. N.; Wade, J. E.
The Federal Advanced Wind Turbine Program
The development of technologically advanced, higher efficiency wind turbines has been identified as a high priority activity by the US wind industry. The Department of Energy's Wind Energy Program has begun a multi-year development program aimed at assisting the wind industry with the design, development, and testing of advanced wind turbine systems that can compete with conventional electric generation for $0.05/kWh at 13 mph sites by the mid-1990s and with fossil-fuel-based generators for $0.04/kWh at 13 mph sites by the year 2000. The development plan consists of four phases: (1) Conceptual Design Studies; (2) Near-Term Product Development; (3) Next Generation Technology Integration and Design, and (4) Next- Generation Technology Development and Testing. The Conceptual Design Studies were begun in late 1990, and are scheduled for completion in the Spring of 1992. Preliminary results from these analyses are very promising and indicate that the goals stated above are technically feasible. This paper includes a brief summary of the Conceptual Design Studies and presents initial plans for the follow-on activities. 3 refs., 4 figs.
Hock, S M; Thresher, R W [National Renewable Energy Lab., Golden, CO (United States); Goldman, P R [USDOE, Washington, DC (United States)
The development of technologically advanced, higher efficiency wind turbines has been identified as a high priority activity by the US wind industry. The Department of Energy`s Wind Energy Program has begun a multi-year development program aimed at assisting the wind industry with the design, development, and testing of advanced wind turbine systems that can compete with conventional electric generation for $0.05/kWh at 13 mph sites by the mid-1990s and with fossil-fuel-based generators for $0.04/kWh at 13 mph sites by the year 2000. The development plan consists of four phases: (1) Conceptual Design Studies; (2) Near-Term Product Development; (3) Next Generation Technology Integration and Design, and (4) Next- Generation Technology Development and Testing. The Conceptual Design Studies were begun in late 1990, and are scheduled for completion in the Spring of 1992. Preliminary results from these analyses are very promising and indicate that the goals stated above are technically feasible. This paper includes a brief summary of the Conceptual Design Studies and presents initial plans for the follow-on activities. 3 refs., 4 figs.
Hock, S.M.; Thresher, R.W. [National Renewable Energy Lab., Golden, CO (United States); Goldman, P.R. [USDOE, Washington, DC (United States)
A thick airfoil is described for the root region of the blade of a wind turbine. The airfoil has a thickness in a range from 24%--26% and a Reynolds number in a range from 1,000,000 to 1,800,000. The airfoil has a maximum lift coefficient of 1.4--1.6 that has minimum sensitivity to roughness effects. 3 Figs.
This article describes a new generation of turbine designs, along with government incentives and support, that are prompting windpower projects with projected performance and economics that seem to satisfy the financiers. Wind-energy powerplants have been struggling to enter that promised land of commercially acceptable electric generation options for almost a decade. Ironically, some environmental groups, once ardent supporters of the technology, are now expressing reservations.
Makansi, J.
Case Study #8: Wind Turbine Control Design
\\u000a In Chap.Ā13, HSSPFC is used to develop a new nonlinear\\/adaptive power flow control strategy for below-rated power control\\u000a of variable speed wind turbines. Fundamentally, the new controller is designed to optimize both stability and performance\\u000a criteria. Numerical results demonstrate that the nonlinear\\/adaptive power flow control increases efficiency, extracting more\\u000a power when compared to a conventional control strategy. In addition, the
Rush Robinett; David Wilson
In the year 2000, 15GW of wind power was installed throughout the world, producing 100PJ of energy annually. This contributes to the total electricity demand by only 0.2%. Both the installed power and the generated energy are increasing by 30% per year world-wide. If the airflow over wind turbine blades could be controlled fully, the generation efficiency and thus the energy production would increase by 9%. Power Control To avoid damage to wind turbines, they are cut out above 10 Beaufort (25 m/s) on the wind speed scale. A turbine could be designed in such a way that it converts as much power as possible in all wind speeds, but then it would have to be to heavy. The high costs of such a design would not be compensated by the extra production in high winds, since such winds are rare. Therefore turbines usually reach maximum power at a much lower wind speed: the rated wind speed, which occurs at about 6 Beaufort (12.5 m/s). Above this rated speed, the power intake is kept constant by a control mechanism. Two different mechanisms are commonly used. Active pitch control, where the blades pitch to vane if the turbine maximum is exceeded or, passive stall control, where the power control is an implicit property of the rotor. Stall Control The flow over airfoils is called "attached" when it flows over the surface from the leading edge to the trailing edge. However, when the angle of attack of the flow exceeds a certain critical angle, the flow does not reach the trailing edge, but leaves the surface at the separation line. Beyond this line the flow direction is reversed, i.e. it flows from the trailing edge backward to the separation line. A blade section extracts much less energy from the flow when it separates. This property is used for stall control. Stall controlled rotors always operate at a constant rotation speed. The angle of attack of the flow incident to the blades is determined by the blade speed and the wind speed. Since the latter is variable, it determines the angle of attack. The art of designing stall rotors is to make the separated area on the blades extend in such a way, that the extracted power remains precisely constant, independent of the wind speed, while the power in the wind at cut-out exceeds the maximum power of the turbine by a factor of 8. Since the stall behaviour is influenced by many parameters, this demand cannot be easily met. However, if it can be met, the advantage of stall control is its passive operation, which is reliable and cheap. Problem Definition In practical application, stall control is not very accurate and many stall-controlled turbines do not meet their specifications. Deviations of the design-power in the order of tens of percent are regular. In the nineties, the aerodynamic research on these deviations focussed on: profile aerodynamics, computational fluid dynamics, rotational effects on separation and pressure measurements on test turbines. However, this did not adequately solve the actual problems with stall turbines. In this thesis, we therefore formulated the following as the essential question: "Does the separated blade area really extend with the wind speed, as we predict?" To find the answer a measurement technique was required, which 1) was applicable on large commercial wind turbines, 2) could follow the dynamic changes of the stall pattern, 3) was not influenced by the centrifugal force and 4) did not disturb the flow. Such a technique was not available, therefore we decided to develop it. Stall Flag Method For this method, a few hundred indicators are fixed to the rotor blades in a special pattern. These indicators, called "stall flags" are patented by the Netherlands Energy Research Foundation (ECN). They have a retro-reflective area which, depending on the flow direction, is or is not covered. A powerful light source in the field up to 500m behind the turbine illuminates the swept rotor area. The uncovered reflectors reflect the light to the source, where a digital video camera records the dynamic stall patterns. The images are analyse
Corten, G. P.
CFD-based design load analysis of 5MW offshore wind turbine
The structure and aerodynamic loads acting on NREL 5MW reference wind turbine blade are calculated and analyzed based on advanced Computational Fluid Dynamics (CFD) and unsteady Blade Element Momentum (BEM). A detailed examination of the six force components has been carried out (three force components and three moment components). Structure load (gravity and inertia load) and aerodynamic load have been obtained by additional structural calculations (CFD or BEM, respectively,). In CFD method, the Reynolds Average Navier-Stokes approach was applied to solve the continuity equation of mass conservation and momentum balance so that the complex flow around wind turbines was modeled. Written in C programming language, a User Defined Function (UDF) code which defines transient velocity profile according to the Extreme Operating Gust condition was compiled into commercial FLUENT package. Furthermore, the unsteady BEM with 3D stall model has also adopted to investigate load components on wind turbine rotor. The present study introduces a comparison between advanced CFD and unsteady BEM for determining load on wind turbine rotor. Results indicate that there are good agreements between both present methods. It is importantly shown that six load components on wind turbine rotor is significant effect under Extreme Operating Gust (EOG) condition. Using advanced CFD and additional structural calculations, this study has succeeded to construct accuracy numerical methodology to estimate total load of wind turbine that compose of aerodynamic load and structure load.
Tran, T. T.; Ryu, G. J.; Kim, Y. H.; Kim, D. H.
International collaborative research in wind turbine rotor aerodynamics.
Five organizations from four countries are collaborating to conduct detailed wind turbine aerodynamic test programs. Fullscale atmospheric testing will be conducted on turbines configured to measure aerodynamic forces on rotating airfoils. The purpose of ...
D. A. Simms C. P. Butterfield
Disturbance Accommodating Adaptive Control with Application to Wind Turbines
Adaptive control techniques are well suited to applications that have unknown modeling parameters and poorly known operating conditions. Many physical systems experience external disturbances that are persistent or continually recurring. Flexible structures and systems with compliance between components often form a class of systems that fail to meet standard requirements for adaptive control. For these classes of systems, a residual mode filter can restore the ability of the adaptive controller to perform in a stable manner. New theory will be presented that enables adaptive control with accommodation of persistent disturbances using residual mode filters. After a short introduction to some of the control challenges of large utility-scale wind turbines, this theory will be applied to a high-fidelity simulation of a wind turbine.
Frost, Susan
The analysis of rigid hub, three-bladed horizontal-axis, axisymmetric wind turbines in yaw is made using a linearized, four-degree-of-freedom model. The linearized equations of motion of rotor and nacelle are developed using quasi-steady blade element theory and Lagrange's equations. The yaw behavior of the system is studied from coefficients of the equations of motion. Analytical results for two wind turbines are presented and studied. The study shows that yaw tracking error is primarily caused by tower shadow. The contribution of the nacelle to the yaw stability is proved to be a destabilizing one. The yaw stability of a wind turbine in a reverse position is investigated and used for verification of the analysis. The characteristics of yaw static stability are determined primarily by the characteristics of the in-plane force coefficient and the location of the yaw axis relative to the rotor plane. A sensitivity study of the terms in the yaw stiffness coefficient is made. The yaw static stability is strongly affected by a change in the coning angle. Two Fortran computer programs are developed to compute the numerical values of coefficients of the equations of motion. Program listings and sample outputs are included.
Numerous problems associated with yaw exists on free-yaw and yaw-driven wind turbines. Yaw-driven machines experience failures in the yaw drive due to excessive loads, while free-yaw machines experience high yaw rates and frequent misalignment problems. This report describes a theoretical investigation of the yaw behavior of wind turbines, which was carried out by the University of Utah. The basic approach to this analysis was to develop a series of analytical and computer models such that each successive model added complexity and increased accuracy. These models are described and compared to results from other models and also to test data. Comments are made on the models' ability to predict yaw moments and response. Also, useful insight is presented regarding the free-yaw behavior of wind turbines as observed using these models. The most complex of these models is used to predict the coupled free-yaw and flap motions of a rotor. This model, YawDyn, is operational; however, experience with it is limited. Future plans, for further enhancing and validating this model, are also discussed.
Xudong, C.; Hansen, A.; Siedschlag, N.
Simulation Model of Wind Turbine 3p Torque Oscillations due to Wind Shear and Tower Shadow
To determine control structures and possible power quality issues, the dynamic torque generated by the blades of a wind turbine must be represented. This paper presents an analytical formulation of the generated aerodynamic torque of a three bladed wind turbine including effects of wind shear and tower shadow. The comprehensive model includes turbine specific parameters such as radius, height, and
Dale S. L. Dolan; P. W. Lehn
Probabilistic identification of turbines facing high and low wind speeds in a wind farm
Due to growing number of wind turbines (WT) within a wind farm (WF) scheduling of maintenance of turbines within the WF becomes challenging issue. Also, in instances when wind energy curtailments are required it can be difficult to decide which turbines should be shut down first. In this paper, a probabilistic methodology is presented to identify WT in the WF
M. Ali; J. V. Milanovic?; I.-S. Ilie; G. Chicco
Pitch control of wind turbine blades in noisy and unstable wind conditions
In this paper, a new approach for control of the pitch angle of the wind turbine is represented in an unstable and noisy circumstance. Moreover, it is demonstrated that output power of the wind turbine can be efficiently controlled by the proposed control system. This method enhances (amends) the stability of the wind turbine. Besides, it improves the regulation of
Mohsen Faridi; Roghaiyeh Ansari; Seyed Ali Mousavi; Mahsa Dodman
International collaborative research in wind turbine rotor aerodynamics
Five organizations from four countries are collaborating to conduct detailed wind turbine aerodynamic test programs. Fullscale atmospheric testing will be conducted on turbines configured to measure aerodynamic forces on rotating airfoils. The purpose of these test programs is to come to a better understanding of the steady and unsteady aerodynamic behavior of wind turbine rotors, and provide information needed to build accurate aerodynamic models for design codes. Stall, dynamic inflow, yaw conditions, and tower effects all contribute to unknown aerodynamic responses. These unknown responses make it extremely difficult to produce cost-effective wind turbine designs. Turbines behave unexpectedly, experiencing power surges and higher fatigue loads than predicted. In order to evolve state-of-the-art wind turbine designs, these aerodynamic effects must be quantified and understood. This paper describes a coordinated international research effort that is underway to accelerate this key research area, and help develop a more thorough understanding of wind turbine aerodynamics.
Simms, D. A.; Butterfield, C. P.
Innovative design approaches for large wind turbine blades
A preliminary design study of an advanced 50 m blade for utility wind turbines is presented and discussed. The effort was part of the Department of Energy WindPACT Blade System Design Study with the goal to investigate and evaluate design and manufacturing issues for wind turbine blades in the 1-10 MW size range. Two different blade designs are considered and
K. J. Jackson; M. D. Zuteck; C. P. van Dam; K. J. Standish; D. Berry
Response analysis of spar platform with wind turbine
Floating wind turbine platforms are the most economical means for deploying offshore wind turbines in deep waters. The merit of spar platform is the large range of topside payloads, favourable motions compared with other floating structures and minimum hull\\/deck interface. The main objective of this paper is to present the response analysis of the spar platform supporting a 5MW wind
Seebai T; Sundaravadivelu R
Active yaw control of MW class wind turbine
While the yaw system of the wind turbine operates depending on the wind direction, it makes us acquire the maximum energy and its own mechanical load decreased. Hence, the optimal design of yaw system is extremely important in the design process of the wind turbine. In this study, yaw system is introduced and its efficiency is analyzed by the result
Han-Soon Choi; Jeong-Gi Kim; Jang-Hwan Cho; Yoon-su Nam
Review of failures and condition monitoring in wind turbine generators
Increasing wind power generation quantity in power systems needs obviously reliable operation. Therefore, accurate condition monitoring and fault diagnosis are almost mandatory. This paper aims to report recent works on condition monitoring and fault diagnosis for wind turbine generators. Wind turbines are subjected to different sort of failures, thus before stating condition monitoring and fault diagnosis methods it is necessary
Z. Daneshi-Far; G. A. Capolino; H. Henao
Multi-speed electrical generator application to wind turbines
A cost-effective method to achieve increased energy conversion from wind turbine generators is presented. Most large wind turbines designed to supply electricity to a power have been optimized at a single rotor speed to maintain synchronism with the grid. Suboptimal performance results from spatial and temporal variation in actual wind speeds. Use of mechanical or electrical devices to allow variable
T. S. Andersen; H. S. Kirschbaum
Using neural networks to estimate wind turbine power generation
This paper uses data collected at Central and South West Services Fort Davis wind farm (USA) to develop a neural network based prediction of power produced by each turbine. The power generated by electric wind turbines changes rapidly because of the continuous fluctuation of wind speed and direction. It is important for the power industry to have the capability to
Shuhui Li; Donald C. Wunsch; Edgar A. O'Hair; Michael G. Giesselmann
Power curve control in micro wind turbine design
In this work, a micro wind turbine will be designed and built for a series of wind tunnel tests (rotor dynamics and Wind Turbine (WT) start-up velocity). Its design stems from an original numerical code, developed by the authors, based on the Blade Element Momentum (BEM) Theory.From classic design criteria, having evaluated all the geometric characteristics, an innovative methodology will
R. Lanzafame; M. Messina
Wind turbine design codes: A comparison of the structural response
The National Wind Technology Center (NWTC) of the National Renewable Energy Laboratory is continuing a comparison of several computer codes used in the design and analysis of wind turbines. The second part of this comparison determined how well the programs predict the structural response of wind turbines. In this paper, the authors compare the structural response for four programs: ADAMS,
M. L. Jr. Buhl; A. D. Wright; K. G. Pierce
Demonstration project: wind turbines for municipal water pumping
In 1979, personnel from Alternative Energy Institute (AEI) studied the feasibility of using wind power in the operation of the municipal water system for the City of Canyon, Texas (1). Predicted energy outputs from six different wind turbines were calculated from power curves and long term National Weather Service (NWS) data. The conclusions were that the cheaper wind turbines should
Depolarization effect in signals scattered by wind turbines
Introduction: Th e increase in the number of wind farms as well as their larger sizes lead to an increase in the possibility of interference with nearby radiocommunication systems. As possible disturbances scattering as well as diffraction from the wind turbine structure are considered. The wind turbines that are being installed nowadays are composed of towers with a height of
I. Etayo; A. Satrustegui; M. Yabar; F. Falcone
Support for spinning reserve from DFIG based wind turbines
With the increased penetration of wind power, wind turbines are now expected to provide ancillary services presently performed by large synchronous generators. Among the ancillary services, frequency duties are vital and a number of papers are available in the literature to demonstrate the possibility of using DFIG based wind turbine for inertia, primary and secondary frequency support. This paper describes
G. Ramtharan; J. B. Ekanayake; N. Jenkins
Electric power from vertical-axis wind turbines
Significant advancements have occurred in vertical axis wind turbine (VAWT) technology for electrical power generation over the last decade; in particular, well-proven aerodynamic and structural analysis codes have been developed for Darrieus-principle wind turbines. Machines of this type have been built by at least three companies, and about 550 units of various designs are currently in service in California wind
K. J. Touryan; J. H. Strickland; D. E. Berg
Short circuit signatures from different wind turbine generator types
Modern wind power plants are required and designed to ride through faults in the network, subjected to the fault clearance and following grid code demands. Beside voltage support during faults, the wind turbine fault current contribution is important to establish the correct settings for the relay of the protections. The following wind turbine generator during faults have been studied: (i)
Jorge Martinez; Philip C. Kjar; Pedro Rodriguez; Remus Teodorescu
Advanced wind turbine design studies: Advanced conceptual study. Final report
In conjunction with the US Department of Energy and the National Renewable Energy Laboratory`s Advanced Wind Turbine Program, the Atlantic Orient Corporation developed preliminary designs for the next generation of wind turbines. These 50 kW and 350 kW turbines are based upon the concept of simplicity. By adhering to a design philosophy that emphasizes simplicity, we project that these turbines
Recent results from data analysis of dynamic stall on wind turbine blades
Wind turbines are subjected to dynamic loading from a variety of different sources. Wind shear and turbulence cause time-varying inflow that results in unsteady airloads. Tower shadow, upwind turbine wakes, and yaw angles also introduce unsteady inflow to wind turbine rotors. Wind turbine designers must predict these loads accurately in order to adequately design blades, hubs, and the remaining support structure to achieve a 30-year life. Structural analysts have not been able to predict mean or dynamic loads accurately enough to predict the fatigue life of major wind turbine components with confidence. Part of the problem is due to uncertainty in the stochastic wind environments as mentioned earlier. Another important part of the problem is the lack of basic knowledge of rotary wing airfoil stall performance. There is mounting evidence that dynamic stall may be related to dynamic loads that are greater than predictions. This paper describes some results of investigations of unsteady aerodynamic loads measured on a wind turbine blade. The objective of the investigation is to understand the steady and unsteady stall behavior of wind turbine blades. 13 refs.
Butterfield, C P; Simms, D [National Renewable Energy Lab., Golden, CO (United States); Huyer, S [Colorado Univ., Boulder, CO (United States)
Safety considerations in the design and operation of large wind turbines
The engineering and safety techniques used to assure the reliable and safe operation of large wind turbine generators utilizing the Mod 2 Wind Turbine System Program as an example is described. The techniques involve a careful definition of the wind turbine's natural and operating environments, use of proven structural design criteria and analysis techniques, an evaluation of potential failure modes and hazards, and use of a fail safe and redundant component engineering philosophy. The role of an effective quality assurance program, tailored to specific hardware criticality, and the checkout and validation program developed to assure system integrity are described.
Reilly, D. H.
Radar-cross-section reduction of wind turbines. part 1.
In recent years, increasing deployment of large wind-turbine farms has become an issue of growing concern for the radar community. The large radar cross section (RCS) presented by wind turbines interferes with radar operation, and the Doppler shift caused by blade rotation causes problems identifying and tracking moving targets. Each new wind-turbine farm installation must be carefully evaluated for potential disruption of radar operation for air defense, air traffic control, weather sensing, and other applications. Several approaches currently exist to minimize conflict between wind-turbine farms and radar installations, including procedural adjustments, radar upgrades, and proper choice of low-impact wind-farm sites, but each has problems with limited effectiveness or prohibitive cost. An alternative approach, heretofore not technically feasible, is to reduce the RCS of wind turbines to the extent that they can be installed near existing radar installations. This report summarizes efforts to reduce wind-turbine RCS, with a particular emphasis on the blades. The report begins with a survey of the wind-turbine RCS-reduction literature to establish a baseline for comparison. The following topics are then addressed: electromagnetic model development and validation, novel material development, integration into wind-turbine fabrication processes, integrated-absorber design, and wind-turbine RCS modeling. Related topics of interest, including alternative mitigation techniques (procedural, at-the-radar, etc.), an introduction to RCS and electromagnetic scattering, and RCS-reduction modeling techniques, can be found in a previous report.
Brock, Billy C.; Loui, Hung; McDonald, Jacob J.; Paquette, Joshua A.; Calkins, David A.; Miller, William K.; Allen, Steven E.; Clem, Paul Gilbert; Patitz, Ward E.
Remote monitoring and nondestructive evaluation of wind turbine towers
Wind turbine towers are in need of condition monitoring so as to lower the cost of unexpected maintenance. Wind loading from turbulence and gusts can cause damage in horizontal axis wind turbines even the supporting towers. Monitoring of wind turbines in service using embedded data sensor arrays usually is not targeted at the turbine-tower interaction from the perspective of structural dynamics. In this study the remote monitoring of the tower supporting a horizontal-axis wind turbine was attempted using a microwave interferometer. The dominant frequency of one tower was found to be decreased by more than 20% in 16 months. Numerical modeling using spectral finite elements is in progress and should provide further information regarding frequency shift due to stiffness variation and added mass. Expected outcome will contribute to remote monitoring procedures and nondestructive evaluation techniques for local wind turbine structures during operation.
Chiang, Chih-Hung; Yu, Chih-Peng; Hsu, Keng-Tsang; Cheng, Chia-Chi; Ke, Ying-Tzu; Shih, Yi-Ru
Response of the Mod-OA wind-turbine rotor to turbulent atmospheric wind
The fluctuating loads caused by the atmospheric turbulence are described. The wind turbulence inputs are determined in three basic modeling steps: (1) the turbulent velocity field is characterized by a model which provides the correlation between velocity components at different spatial positions and at different times; (2) the velocity field is approximated in the rotor disk plane using a series expansion which includes terms that are uniform across the rotor disk, gradient terms which vary linearly across the disk, and terms which vary quadratically across the disk, all of these terms are time dependent; (3) simple rational spectral representations are determined which approximate the derived correlation model for these turbulence components. The correlation between velocities at spatially separated points is characterized by the Von Karman model. Quasisteady linear aerodynamic theory is used to compute the forces on the rotor blades of the Mod-OA wind turbine operating in a turbulent flow. The blade used for these computations is the fiberglass blade in place on the Mod-OA turbine. The turbulence and aerodynamic model are combined and the following rotor responses are computed: thurst, torque, pitch and yaw moments, and blade root bending moments. These computations were made for the case of fixed pitch operation and incorporate the influence of a linear mean wind shear. Results presented include power spectral density plots of the wind and turbine outputs for three different mean wind conditions. The various responses are compared to determine the relative importance of the turbulence inputs on rotor blade loads.
Thresher, R. W.; Holley, W. E.; Hershberg, E. L.; Lin, S. R.
Wind Resource Estimation: From Trades to Turbines
Ris° DTU has been involved in wind resource estimation for many years. Initially, we used observed winds and microscale modeling within the WAsP (the Wind Atlas Analysis and Application Program) software. This method has proven very accurate in places such as Denmark where the landscape is relatively flat, the wind climatology is mainly driven by synoptic-scale weather patterns, and where a dense observational network is available. For regions with a sparse observation network or with more complex terrain, large-scale geostrophic winds derived from global reanalysis are brought down to the mesoscale by using a statistical- dynamical downscaling method. The method uses a classification of the large-scale wind patterns which is then adjusted to the higher resolutions by the use of idealized mesoscale model simulations. Once mesoscale-corrected winds classes are calculated, they are linked to microscale models to take into account the true characteristics of the landscape. In both methods the common goal is to create generalized wind climates, from which location-specific wind climates can be calculated. The generalized (or regional) wind climate gives the frequency distributions of wind speed and direction for standardized and idealized terrain conditions. It serves to link mesoscale to microscale and vice-verse. Without this link, it is not possible to make a proper verification of wind climates derived from modeling against measured winds or apply the mesoscale results for wind farm studies. The results of the statistical-dynamical approach are not as accurate in regions where topographically forced and thermally induced effects dominate the boundary layer wind climatology. For this reason, we are currently developing enhancements to the system by exploring the use of stronger dynamical components to the statistical-dynamical method including comparison to a purely dynamical downscaling simulation for the area of interest. In this presentation we will discuss the range of methods and give examples of recent applications to wind atlas generation.
Hahmann, A. N.; Badger, J.; Mortensen, N. G.; J°rgensen, H. E.
Dynamic modeling of doubly fed induction generator wind turbines
It is now recognized that many large wind farms will employ doubly fed induction generator (DFIG) variable speed wind turbines. A number of such wind farms are already in operation and more are planned or under construction. With the rising penetration of wind power into electricity networks, increasingly comprehensive studies are required to identify the interaction between the wind farm(s)
Janaka B. Ekanayake; Lee Holdsworth; XueGuang Wu; Nicholas Jenkins
Wind turbine inspection tests at UCSD
The wind energy industry is rapidly growing in order to meet the increasing world energy demands as well as the need for clean and renewable energy sources. With the goal to explore new technologies and innovations which could help potentially improve the efficiency and effectiveness of wind energy, the NDE/SHM laboratory at UCSD acquired a unique wind turbine blade that will be used for performing several research projects related to wind turbine blade technology and non-destructive inspection techniques. The blade was built using the CX-100 design developed by TPI Composites, Inc. and Sandia National Laboratory (SNL). The 9-m blade was constructed with several embedded defects that represent the most common manufacturing defects typically found, such as out-of-plane waviness, composite delamination, and adhesive disbond. The defects were embedded during the manufacturing process by using similar methods developed by both TPI and SNL for simulating actual defect characteristics. Though the blade is small in comparison to the average utility sized blade of around 40 meters, the blade features similar materials and manufacturing methods, allowing for several inspections techniques to be studied on a representative platform. The inspection techniques include advanced infrared thermography and other guided wave techniques.
Tippmann, Jeffery D.; Manohar, Arun; Lanza di Scalea, Francesco
NREL Establishes a 1.5-MW Wind Turbine Test Platform for Research Partnerships (Fact Sheet)
Research turbine supports sustained technology development. For more than three decades, engineers at the National Renewable Energy Laboratory's (NREL) National Wind Technology Center (NWTC) have worked with the U.S. Department of Energy (DOE) Wind Program and industry partners to advance wind energy technology, improve wind turbine performance, and reduce the cost of energy. Although there have been dramatic increases in performance and drops in the cost of wind energy-from $0.80 per kilowatt-hour to between $0.06 and $0.08 per kilowatt-hour-the goal of the DOE Wind Program is to further increase performance and reduce the cost of energy for land-based systems so that wind energy can compete with natural gas by 2020. In support of the program's research and development (R and D) efforts, NREL has constructed state-of-the-art facilities at the NWTC where industry partners, universities, and other DOE laboratories can conduct tests and experiments to further advance wind technology. The latest facility to come online is the DOE-GE 1.5-MW wind turbine test platform. Working with DOE, NREL purchased and installed a GE 1.5-MW wind turbine at the NWTC in 2009. Since then, NREL engineers have extensively instrumented the machine, conducted power performance and full-system modal tests, and collected structural loads measurements to obtain baseline characterization of the turbine's power curve, vibration characteristics, and fatigue loads in the uniquely challenging NWTC inflow environment. By successfully completing a baseline for the turbine's performance and structural response, NREL engineers have established a test platform that can be used by industry, university, and DOE laboratory researchers to test wind turbine control systems and components. The new test platform will also enable researchers to acquire the measurements needed to develop and validate wind turbine models and improve design codes.
Not Available
Development of methodology for horizontal axis wind turbine dynamic analysis
Horizontal axis wind turbine dynamics were studied. The following findings are summarized: (1) review of the MOSTAS computer programs for dynamic analysis of horizontal axis wind turbines; (2) review of various analysis methods for rotating systems with periodic coefficients; (3) review of structural dynamics analysis tools for large wind turbine; (4) experiments for yaw characteristics of a rotating rotor; (5) development of a finite element model for rotors; (6) development of simple models for aeroelastics; and (7) development of simple models for stability and response of wind turbines on flexible towers.
Dugundji, J.
Probabilistic characterization of wind turbine blades via aeroelasticity and spinning finite element formulation
Wind energy is an increasingly important component of this nation's renewable energy portfolio, however safe and economical wind turbine operation is a critical need to ensure continued adoption. Safe operation of wind turbine structures requires not only information regarding their condition, but their operational environment. Given the difficulty inherent in SHM processes for wind turbines (damage detection, location, and characterization), some uncertainty in conditional assessment is expected. Furthermore, given the stochastic nature of the loading on turbine structures, a probabilistic framework is appropriate to characterize their risk of failure at a given time. Such information will be invaluable to turbine controllers, allowing them to operate the structures within acceptable risk profiles. This study explores the characterization of the turbine loading and response envelopes for critical failure modes of the turbine blade structures. A framework is presented to develop an analytical estimation of the loading environment (including loading effects) based on the dynamic behavior of the blades. This is influenced by behaviors including along and across-wind aero-elastic effects, wind shear gradient, tower shadow effects, and centrifugal stiffening effects. The proposed solution includes methods that are based on modal decomposition of the blades and require frequent updates to the estimated modal properties to account for the time-varying nature of the turbine and its environment. The estimated demand statistics are compared to a code-based resistance curve to determine a probabilistic estimate of the risk of blade failure given the loading environment.
Velazquez, Antonio; Swartz, R. Andrew
An examination of loads and responses of a wind turbine undergoing variable-speed operation
The National Renewable Energy Laboratory has recently developed the ability to predict turbine loads and responses for machines undergoing variable-speed operation. The wind industry has debated the potential benefits of operating wind turbine sat variable speeds for some time. Turbine system dynamic responses (structural response, resonance, and component interactions) are an important consideration for variable-speed operation of wind turbines. The authors have implemented simple, variable-speed control algorithms for both the FAST and ADAMS dynamics codes. The control algorithm is a simple one, allowing the turbine to track the optimum power coefficient (C{sub p}). The objective of this paper is to show turbine loads and responses for a particular two-bladed, teetering-hub, downwind turbine undergoing variable-speed operation. The authors examined the response of the machine to various turbulent wind inflow conditions. In addition, they compare the structural responses under fixed-speed and variable-speed operation. For this paper, they restrict their comparisons to those wind-speed ranges for which limiting power by some additional control strategy (blade pitch or aileron control, for example) is not necessary. The objective here is to develop a basic understanding of the differences in loads and responses between the fixed-speed and variable-speed operation of this wind turbine configuration.
Wright, A.D.; Buhl, M.L. Jr.; Bir, G.S.
Matching wind turbine rotors and loads: Computational methods for designers
A comprehensive method for matching wind energy conversion system (WECS) rotors with the load characteristics of common electrical and mechanical applications was reported. A method was developed to convert the data into useful results: (1) from turbine efficiency and load torque characteristics, turbine power is predicted as a function of windspeed; (2) it is decided how turbine power is to be governed to insure safety of all components; (3) mechanical conversion efficiency comes into play to predict how useful delivered power varies with windspeed; (4) wind statistics are used to predict longterm energy output. Most systems are approximated by a graph and calculator approach. The method leads to energy predictions, and to insight into modeled processes. A computer program provides more sophisticated calculations where a highly unusual system is to be modeled, where accuracy is at a premium, or where error analysis is required. The analysis is fleshed out with in depth case studies for induction generator and inverter utility systems; battery chargers; resistance heaters; positive displacement pumps; including three different load compensation strategies; and centrifugal pumps with unregulated electric power transmission from turbine to pump.
Seale, J. B.
Spatial mapping and attribution of Wyoming wind turbines, 2012
USGS Publications Warehouse
These data represent locations of wind turbines found within Wyoming as of August 2012. We assigned each wind turbine to a wind farm and, in these data, provide information about each turbineÆs potential megawatt output, rotor diameter, hub height, rotor height, the status of the land ownership where the turbine exists, the county each turbine is located in, wind farm power capacity, the number of units currently associated with each wind farm, the wind turbine manufacturer and model, the wind farm developer, the owner of the wind farm, the current purchaser of power from the wind farm, the year the wind farm went online, and the status of its operation. Some of the attributes are estimates based on the information we found via the American Wind Energy Association and other on-line reports. The locations are derived from National Agriculture Imagery Program (2009 and 2012) true color aerial photographs and have a positional accuracy of approximately +/-5 meters. These data will provide a planning tool for wildlife- and habitat-related projects underway at the U.S. Geological SurveyÆs Fort Collins Science Center and other government and non-government organizations. Specifically, we will use these data to support quantifying disturbances of the landscape as related to wind energy as well as to quantify indirect disturbances to flora and fauna. This data set represents an update to a previous version by OÆDonnell and Fancher (2010).
O'Donnell, Michael S.; Fancher, Tammy S.
Actuator control of edgewise vibrations in wind turbine blades
Edgewise vibrations with low aerodynamic damping are of particular concern in modern multi-megawatt wind turbines, as large amplitude cyclic oscillations may significantly shorten the life-time of wind turbine components, and even lead to structural damages or failures. In this paper, a new blade design with active controllers is proposed for controlling edgewise vibrations. The control is based on a pair of actuators/active tendons mounted inside each blade, allowing a variable control force to be applied in the edgewise direction. The control forces are appropriately manipulated according to a prescribed control law. A mathematical model of the wind turbine equipped with active controllers has been formulated using an Euler-Lagrangian approach. The model describes the dynamics of edgewise vibrations considering the aerodynamic properties of the blade, variable mass and stiffness per unit length and taking into account the effect of centrifugal stiffening, gravity and the interaction between the blades and the tower. Aerodynamic loads corresponding to a combination of steady wind including the wind shear and the effect of turbulence are computed by applying the modified Blade Element Momentum (BEM) theory. Multi-Blade Coordinate (MBC) transformation is applied to an edgewise reduced order model, leading to a linear time-invariant (LTI) representation of the dynamic model. The LTI description obtained is used for the design of the active control algorithm. Linear Quadratic (LQ) regulator designed for the MBC transformed system is compared with the control synthesis performed directly on an assumed nominal representation of the time-varying system. The LQ regulator is also compared against vibration control performance using Direct Velocity Feedback (DVF). Numerical simulations have been carried out using data from a 5-MW three-bladed Horizontal-Axis Wind Turbine (HAWT) model in order to study the effectiveness of the proposed active controlled blade design in reducing edgewise vibrations. Results show that the use of the proposed control scheme significantly improves the response of the blade and promising performances can be achieved. Furthermore, under the conditions considered in this study quantitative comparisons of the LQ-based control strategies reveal that there is a marginal improvement in the performances obtained by applying the MBC transformation on the time-varying edgewise vibration model of the wind turbine.
Staino, A.; Basu, B.; Nielsen, S. R. K.
Analysis of wind turbines in yaw
The yaw problems of a three-bladed, downwind, horizontal axis wind turbine are examined in this report. A four-degree-of-freedom system was chosen to model the turbine. Linearized equations of rotor and nacelle motion were developed using the energy method and Lagrange's equations. Quasi-steady blade element and momentum theories were used in developing the axial induction factor and aerodynamic loads. A computer code was developed to obtain the numerical values of coefficients of the equations of motion, thus allowing the cause of yaw instability to be studied. The study indicated that yaw tracking error is primarily caused by tower shadow. However, the wind turbine studied - besides being unstable in yaw under normal operating conditions - has an additional problem in that the nacelle shape contributes to additional instability. Blade coning, in the present design, is inadequate to overcome this instability. The sensitivity of the system stiffness coefficients to the selected input parameters was studied, and results indicate that the system stiffness coefficient is highly sensitive to the coning angle. Increasing the coning angle could significantly increase the stiffness coefficient and lead to improvement of system stability.
Wilson, R.E.; Chaiyapinunt, S.
Structural Dynamic Behavior of Wind Turbines
The structural dynamicist s areas of responsibility require interaction with most other members of the wind turbine project team. These responsibilities are to predict structural loads and deflections that will occur over the lifetime of the machine, ensure favorable dynamic responses through appropriate design and operational procedures, evaluate potential design improvements for their impact on dynamic loads and stability, and correlate load and control test data with design predictions. Load prediction has been a major concern in wind turbine designs to date, and it is perhaps the single most important task faced by the structural dynamics engineer. However, even if we were able to predict all loads perfectly, this in itself would not lead to an economic system. Reduction of dynamic loads, not merely a "design to loads" policy, is required to achieve a cost-effective design. The two processes of load prediction and structural design are highly interactive: loads and deflections must be known before designers and stress analysts can perform structural sizing, which in turn influences the loads through changes in stiffness and mass. Structural design identifies "hot spots" (local areas of high stress) that would benefit most from dynamic load alleviation. Convergence of this cycle leads to a turbine structure that is neither under-designed (which may result in structural failure), nor over-designed (which will lead to excessive weight and cost).
Thresher, Robert W.; Mirandy, Louis P.; Carne, Thomas G.; Lobitz, Donald W.; James, George H. III
The yaw problems of a three-bladed, downwind, horizontal axis wind turbine are examined. A four-degree-of-freedom system was chosen to model the turbine. Linearized equations of rotor and nacelle motion were developed using the energy method and Lagrange's equations. Quasi-steady blade element and momentum theories were used in developing the axial induction factor and aerodynamic loads. A computer code was developed to obtain the numerical values of coefficients of the equations of motion, thus allowing the cause of yaw instability to be studied. The study indicated that yaw tracking error is primarily caused by tower shadow. However, the wind turbine studied, besides being unstable in yaw under normal operating conditions, has an additional problem in that the nacelle shape contributes to additional instability. Blade coming, in the present design, is inadequate to overcome this instability. The sensitivity of the system stiffness coefficients to the selected input parameters was studied, and results indicate that the system stiffness coefficient is highly sensitive to the coning angle. Increasing the coning angle could significantly increase the stiffness coefficient and lead to improvement of system stability.
Wilson, R. E.; Chaiyapinunt, S.
76 FR 18238 - Wind Turbine Guidelines Advisory Committee; Announcement of Public Meeting
...FWS-R9-FHC-2011-N061; 94300-1122-0000-Z2] Wind Turbine Guidelines Advisory Committee...Service (Service), will host a Wind Turbine Guidelines Advisory Committee...Alternate Designated Federal Officer, Wind Turbine Guidelines Advisory...
77 FR 32497 - Grant of Authority for Subzone Status; Mitsubishi Power Systems Americas, Inc. (Wind Turbine...
...Power Systems Americas, Inc. (Wind Turbine Nacelles and Generating Sets...special-purpose subzone at the wind turbine nacelle and generating set manufacturing...related to the manufacturing of wind turbine nacelles and generating sets...
76 FR 54481 - Wind Turbine Guidelines Advisory Committee; Announcement of Public Meeting and Webcast
...94300-1122-0000-Z2] RIN 1018-AX45 Wind Turbine Guidelines Advisory Committee...Service (Service), will host a Wind Turbine Guidelines Advisory Committee...Alternate Designated Federal Officer, Wind Turbine Guidelines Advisory...
76 FR 38677 - Wind Turbine Guidelines Advisory Committee; Announcement of Public Meeting and Webcast
...FWS-R9-FHC-2011-N137; 94300-1122-0000-Z2] Wind Turbine Guidelines Advisory Committee...Service (Service), will host a Wind Turbine Guidelines Advisory Committee...Alternate Designated Federal Officer, Wind Turbine Guidelines Advisory...
76 FR 20006 - Wind Turbine Guidelines Advisory Committee; Teleconference Line Available for Public Meeting
A shape adaptive airfoil for a wind turbine blade
The loads on wind turbine components are primarily from the blades. It is important to control these blade loads in order to avoid damaging the wind turbine. Rotor control technology is currently limited to controlling the rotor speed and the pitch of the blades. As blades increase in length it becomes less desirable to pitch the entire blade as a single rigid body, but instead there is a requirement to control loads more precisely along the length of the blade. This can be achieved with aerodynamic control devices such as flaps. Morphing technologies are good candidates for wind turbine flaps because they have the potential to create structures that have the conflicting abilities of being load carrying, light-weight and shape adaptive. A morphing flap design with a highly anisotropic cellular structure is presented which is able to undergo large deflections and high strains without a large actuation penalty. An aeroelastic analysis couples the work done by aerodynamic loads on the flap, the flap strain energy and the required actuation work to change shape. The morphing flap is experimentally validated with a manufactured demonstrator and shown to have reduced actuation requirements compared to a conventional hinged flap.
Daynes, Stephen; Weaver, Paul M.
We report an experimental study to characterize the dynamic wind loads and evolution of wake vortex flow structures downstream of a horizontal axis wind turbine (HAWT). The experiments were conducted in a wind tunnel with a wind turbine model placed in a boundary layer flow developed over rough and smooth surfaces in order to study the effects of roughness and
Hui Hu; Zifeng Yang; Partha Sarkar
Chances in wind energy: a probalistic approach to wind turbine fatigue design
Wind is becoming an ever more important source of renewable energy: installed wind turbine power now stands at 60,000 MW worldwide, providing 0.6% of world electricity demand. Still it is important that the cost of wind energy is brought down further, which means that wind turbines must be designed to be exactly as strong as necessary, but no stronger. Hence
Herman Frederik Veldkamp
Wind tunnel investigation of the wake structure within small wind turbine farms.
The primary aim of the work reported here was to obtain comprehensive data on the mean and turbulent flow within wind farms of horizontal axis wind turbines. Wakes within wind farms of 15 wind turbine models have been investigated in some detail in the la...
U. Hassan
Rotationally sampled wind characteristics and correlations with MOD-OA wind turbine response
This report presents results of a comprehensive wind and wind turbine measurement program: the Clayton, New Mexico, vertical plane array/MOD-OA project. In this experiment, the turbulent wind was measured for a large array of fixed anemometers located two blade diameters upwind of a 200-kW horizontal-axis wind turbine (HAWT). Simultaneously, key wind turbine response parameters were also measured. The first of two major objectives of this experiment was to determine the turbulent wind, rotationally sampled to emulate the motion of the wind turbine blade, for the range of different wind speeds and stability classes actually experienced by the wind turbine. The second major objective was to correlate this rotationally sampled wind with the wind turbine blade stress and power, in order to assess the usefulness of the wind measurements for wind turbine loads testing a prediction. Time series of rotationally sampled winds and wind turbine blade bending moments and power were converted to frequency spectra using Fourier transform techniques. These spectra were used as the basis for both qualitative and quantitative comparisons among the various cases. A quantitative comparison between the rotationally sampled wind input and blade bending response was made, using the Fourier spectra to estimate the blade transfer function. These transfer functions were then used to calculate an approximate damping coefficient for the MOD-OA fiberglass blade.
George, R.L.; Connell, J.R.
Wind Turbine Generator System Power Performance Test Report for the Gaia-Wind 11-kW Wind Turbine
This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. It is a power performance test that the National Renewable Energy Laboratory (NREL) conducted on the Gaia-Wind 11-kW small wind turbine.
Wind turbines in icing conditions: performance and prediction
Wind farms in cold climate regions have an estimated installed capacity of 3 GW which constantly increases, e.g., in Scandinavia, the Alpine region, and North America. One significant problem in cold climate regions is icing. Icing on wind turbines causes a variety of problems: reduction of power production, overloading due to delayed stall, increased fatigue of components and risk of ice throw. Thus, power forecasts considering icing are important to optimize performance and to minimize risks. The present study aims at investigating how well the effect of icing can be included in power predictions. Studies concentrate on in-cloud icing - the most frequent reason for atmospheric icing on structures in most countries. Wind power production is predicted using the weather forecast model WRF coupled with a Kalman filter and an icing algorithm. The icing algorithm calculates ice load based on temperature, wind, cloud and rain water content from the WRF results. In previous studies, the model system demonstrated the ability to predict icing events. Forecasts will be simulated for a test site in complex terrain in Switzerland. It consists of two wind turbines equipped with wind, temperature, humidity and longwave radiation sensors. Additional equipment with regard to icing are two webcams monitoring icing on blades and anemometers and an icing sensor. LIDAR measurements were carried out in January 2010 to measure an undisturbed vertical wind profile. During winter 2009/2010 longer icing periods of a total length of 9 days and several shorter icing periods were observed. These icing events are used to evaluate the wind power forecasts under icing conditions.
Dierer, S.; Oechslin, R.; Cattin, R.
Certification for Small Wind Turbine Installers: What's the Hang Up.
Several programs have been implemented to support the advancement of a professional, mature small wind industry and to ensure that this industry moves forward in a sustainable direction. The development of a standard for small wind turbine systems and the...
F. Oteri K. Sinclair
Fatigue Evaluation of Wind Turbines. Part 1: Theoretical Background.
The theoretical background for the computation of fatigue damage in horizontal axis wind turbines is described. Input data are meteorological statistics of mean wind velocities, autospectra, two point coherence- and phase spectra of turbulence, together w...
A. Raab B. Winzell U. Hjorth
Fatigue case study and reliability analyses for wind turbines.
Modern wind turbines are fatigue critical machines used to produce electrical power. To insure long term, reliable operation, their structure must be optimized if they are to be economically viable. The fatigue and reliability projects in Sandia's Wind En...
H. J. Sutherland, P. S. Veers
Large-eddy simulation of wind-turbine wakes: Evaluation of turbine parameterizations
Large-eddy simulation (LES) offers a great potential to study the effects of turbulent atmospheric boundary layer flow on the performance of wind turbines and wind farms. The accuracy of the simulations, however, hinges on our ability to parameterize subgrid-scale (SGS) turbulent fluxes as well as turbine-induced forces. In this study, we investigate the performance of LES in simulations of wind-turbine
Fernando Porte-Agel; Yu-Tin Wu; Hao Lu; Leonardo Chamorro
Darrieus wind-turbine airfoil configurations
The purpose was to determine what aerodynamic performance improvement, if any, could be achieved by judiciously choosing the airfoil sections for Darrieus wind turbine blades. Ten different airfoils, having thickness to chord ratios of twelve, fifteen and eighteen percent, were investigated. Performance calculations indicated that the NACA 6-series airfoils yield peak power coefficients at least as great as the NACA. Furthermore, the power coefficient-tip speed ratio curves were broader and flatter for the 6-series airfoils. Sample calculations for an NACA 63 sub 2-015 airfoil showed an annual energy output increase of 17 to 27% depending upon rotor solidity, compared to an NACA 0015 airfoil. An attempt was made to account for the flow curvature effects associated with Darrieus turbines by transforming the NACA 63 sub 2-015 airfoil to an appropriate shape.
Migliore, P. G.; Fritschen, J. R.
Preliminary results of the large experimental wind turbine phase of the national wind energy program
The preliminary results of two projects in the development phase of reliable wind turbines designed to supply cost-competitive electrical energy were discussed. An experimental 100 kW wind turbine design and its status are first reviewed. The results of two parallel design studies for determining the configurations and power levels for wind turbines with minimum energy costs are also discussed. These studies predict wind energy costs of 1.5 to 7 cents per kW-h for wind turbines produced in quantities of 100 to 1000 per year and located at sites having average winds of 12 to 18 mph.
Thomas, R. L.; Sholes, T.; Sholes, J. E.
Current research to optimize wind turbine designs centers on the most important parameter, the useful lifetime of the rotor assembly. A rotor design which promises to extend the lifetime of the full rotor assembly is discussed. That design improvement includes the integration of a teetered rotor hub and a delta-3 angle. This design concept was proven in helicopter and rotor craft applications. The adaptation to wind turbines was the primary task of this appropriate technology utilization project. Test rotors, incorporating the teetering hub, delta-3 angle design, were constructed and tested. The research model provides a full range of settings for a complete evaluation of the relevant parameters; e.g., the delta-3 angle is variable from +70 to -70(0), the rotor position may be varied fore and aft of the teeter axis, the teeter spring rate is continuously variable, also the teeter and yaw stops are adjustable. The use of a dc generator permits the rotor to change angular speed with wind speed. The lack of a yaw drive allows the rotor to display its own passive yawing rates and accommodation factors as a function of delta-3 angle, rotor axis position, and teeter spring rate settings.
Bryant, P. J.
The effect of nacelle motion should be considered when calculating the wind speed relative to the wind turbine structure, which is essential in wind turbine control and performance testing. A Kalman filter approach is applied to estimate the nacelle motion of a wind turbine. Information from several accelerometers and strain gauges which are installed on the wind turbine tower is combined with the Kalman filter. An optimization algorithm is used to choose the optimal locations for strain gauge and accelerometer installation. A laboratory-scale experimental rig which mimics the tower and nacelle of the wind turbine is constructed to evaluate the performance of the proposed estimator algorithm. The usefulness of the proposed algorithm is validated by these laboratory-scale experimental results.
Nam, Yoonsu; Yoon, Tai Jun
In-field use of laser Doppler vibrometer on a wind turbine blade
One of our primary goals was to determine how well a laser Doppler vibrometer (LDV) could measure the structural dynamic response of a wind turbine that was parked in the field. We performed a series of preliminary tests in the lab to determine the basic limitations of the LDV for this application. We then instrumented an installed parked horizontal axis wind turbine with accelerometers to determine the natural frequencies, damping, and mode shapes of the wind turbine and rotor as a baseline for the LDV and our other tests. We also wanted to determine if LDV modal information could be obtained from a naturally (wind) excited wind turbine. We compared concurrently obtained accelerometer and LDV data in an attempt to assess the quality of the LDV data. Our test results indicate the LDV can be successfully used in the field environment of an installed wind turbine, but with a few restrictions. We were successful in obtaining modal information from a naturally (wind) excited wind turbine in the field, but the data analysis requires a large number of averaged data sets to obtain reasonable results. An ultimate goal of this continuing project is to develop a technique that will monitor the health of a structure, detect damage, and hopefully predict an impending component failure.
Rumsey, M.; Hurtado, J.; Hansche, B. [and others
Multi-piece wind turbine rotor blades and wind turbines incorporating same
A multisection blade for a wind turbine includes a hub extender having a pitch bearing at one end, a skirt or fairing having a hole therethrough and configured to mount over the hub extender, and an outboard section configured to couple to the pitch bearing.
Moroz; Emilian Mieczyslaw (San Diego, CA) [San Diego, CA
Wind Turbines Make Waves: Why Some Residents near Wind Turbines Become Ill
People who live near wind turbines complain of symptoms that include some combination of the following: difficulty sleeping, fatigue, depression, irritability, aggressiveness, cognitive dysfunction, chest pain/pressure, headaches, joint pain, skin irritations, nausea, dizziness, tinnitus, and stress. These symptoms have been attributed to theģ
Havas, Magda; Colling, David
Reference Wind Speed Distributions and Height Profiles for Wind Turbine Design and Performance Evaluation Applications.
The purpose of this report is to provide a set of reference or standard values of wind profiles, wind speed distributions and their effects on wind turbine performance for engineering design applications. Based on measured Weibull distribution parameters,...
A. Mikhail C. G. Justus W. R. Hargraves
Controlled Velocity Testing of an 8-kW Wind Turbine
This paper describes a case study of the controlled-velocity test of an 8-kW wind turbine. The turbine was developed in response to the U.S. Department of Energy's small wind turbine program. As background, the prototype development is discussed. The turbine mechanical and electrical components are described. The turbine was tested on a flatbed truck and driven down an airfield runway at constant relative wind speed. Horizontal furling was used to control over-speed. Various parameters were changed to determine their effects on furling. The testing showed that the machine had insufficient rotor offset for adequate furling. Also, a rotor resonance problem was discovered and remedied. Problems associated with taking the measurements made it difficult to determine if the truck test was a suitable method for code validation. However, qualitative observations gleaned from the testing justified the effort.
Larwood, S.; Sencenbaugh, J.; Acker, B.
MOD-0 wind turbine dynamics test correlations
The behavior of the teetered, downwind, free yaw, MOD-0 wind turbine, as represented by NASA dynamic test data, was used to support confidence in the Hamilton Standard computer code simulations. Trim position, performance at trim, and teeter response as predicted by the computer codes were compared to test results. Using the computer codes, other possible configurations for MOD-0 were investigated. Several new test configurations are recommended for exploring free yaw behavior. It is shown that eliminating rotor tilt and optimizing cooling and blade twist can contribute to good free yaw behavior and stability. The effects of rotor teeter, teeter gravity balance, inflow and other physical and operating parameters were also investigated.
Brooks, B. M.
Fatigue behavior for a variety of generic materials used in wind turbine blades was explored. Coupon testing was carried out under constant amplitude tensile fatigue loading to beyond 10(exp 7) cycles for most materials. Unidirectional materials performed close to expectations despite fiber misalignment. Materials with triaxial (0/plus or minus 45) reinforcement showed greater fatigue sensitivity than expected, but lifetime trends flattened at high cycles. The uniaxial and triaxial materials could be normalized to a single S-N lifetime trend for each case. Results include the effects of differing matrix materials, manufacturing methods, reinforcement structure, and ply terminations.
Mandell, J. F.; Reed, R. M.; Samborsky, D. D.
PSCAD\\/EMTDC based dynamic modeling and analysis of a variable speed wind turbine
The paper presents dynamic modeling and simulation of a grid connected variable speed wind turbine (VSWT) using PSCAD\\/EMTDC, a widely used power system transient analysis tool. A variable speed wind generator with power electronics interface is modeled for dynamic simulation analysis. Component models and equations are addressed and their incorporations into the EMTDC are provided. Controllable power inverter strategies are
Seul-Ki Kim; Eung-Sang Kim; Jae-Young Yoon; Ho-Yong Kim
Fluid-Structure Interaction Analysis of Wind Turbines
Countries around the world are putting substantial effort into the development of wind energy technologies. The urgent need of renewable energy puts pressure on the wind energy industry research and development to enhance the current wind generation capabilities and decrease the associated costs. Currently most wind turbine aerodynamics and aeroelasticity simulations are performed using low-fidelity methods. These methods are simple to implement and fast to execute; however, the cases involving important features, such as unsteady flow, turbulence, and details of the wind turbine geometry, are beyond their range of applicability. In this dissertation, we introduce a paradigm shift in wind turbine analysis by developing 3D, complex geometry, time-dependent, multi-physics modeling procedures for wind turbine fluid-structure interaction (FSI). The proposed framework consists of a collection of numerical methods combined into a single framework for FSI modeling and simulation of wind turbines at full scale. The use of the Navier-Stokes equations of incompressible flows for wind turbine aerodynamics is validated against experimental data. The structural modeling of the composite blades is based on the Kirchhoff-Love thin shell theory discretized using isogeometric analysis. The coupled FSI formulation is derived using the augmented Lagrangian approach and accommodates non-matching fluid-structure interface discretizations. The challenges of fluid-structural coupling and the handling of computational domains in relative motion are discussed, and the FSI computations of a 5 MW offshore baseline wind turbine are shown.
Hsu, Ming-Chen
Applications of an improved equivalent wind method for the aggregation of DFIG wind turbines
Recently wind energy has developed at a fast pace, and it is necessary to develop equivalent models to represent dynamic behaviors of wind farms on power system. The equivalent wind method has been investigated for the aggregation of DFIG wind turbines. The detailed procedure for the calculation of equivalent wind has been analyzed. The necessity of classifying incoming winds has
Z. J. Meng; F. Xue; Kang Chang; Maosheng Ding; Jun Zhang; Li Xiang; Jiafeng Shi; Xiaoyu Li
Improving the performance of the equivalent wind method for the aggregation of DFIG wind turbines
Z. J. Meng; F. Xue
An Investigation of the Equivalent Wind Method for the Aggregation of DFIG Wind Turbines
Using Dynamically Coupled Turbine\\/Wind Simulations to Investigate the Influence of Atmospheric Turbulence in Turbine Wake Recovery
In order to increase our efficiency of energy capture in wind farms, optimize turbine arrangements, and adapt wind-turbine technology to optimal performance in common atmospheric conditions such as low level jets (LLJ), it is critical to understand the dynamic interactions between turbulence and multiple wind turbines. Ambient atmospheric turbulence interacts with spinning turbines producing the critical mechanism for the recovery
R. Linn; E. Koo; N. D. Kelley; B. Jonkman; J. K. Lundquist; J. Canfield
Control of Wind Turbines: Past, Present, and Future
We review the objectives and techniques used in the control of horizontal axis wind turbines at the individual turbine level, where controls are applied to the turbine blade pitch and generator. The turbine system is modeled as a flexible structure operating in the presence of turbulent wind disturbances. Some overview of the various stages of turbine operation and control strategies used to maximize energy capture in below rated wind speeds is given, but emphasis is on control to alleviate loads when the turbine is operating at maximum power. After reviewing basic turbine control objectives, we provide an overview of the common basic linear control approaches and then describe more advanced control architectures and why they may provide significant advantages.
Laks, J. H.; Pao, L. Y.; Wright, A. D.
(Construction of a wind turbine). Final report
A wind powered electrical generator was built by industrial arts students working in electricity, woodworking, and metal technology facilities. The blades were originally aluminum frames covered with sailcloth. These were replaced with hand-carved laminated basswood blades. Original plans called for a bullet and downwind propeller, but this was replaced with an upwind propeller and an aft-mounted tailfin. A V-belt and pulley drive transmits power from the turbine and a motorcycle brake stops the machine during high winds and/or for safe servicing. The original 13 volt, 105 amp alternator was replaced by a 12 volt, 100 amp dc generator. Publicity and dissemination events are listed as well as expenditures. (LEW)
Devine, L.E.
A wind turbine includes a yaw spring return assembly to return the nacelle from a position to which it has been rotated by yawing forces, thus preventing excessive twisting of the power cables and control cables. It also includes negative coning restrainers to limit the bending of the flexible arms of the rotor towards the tower, and stop means on the rotor shaft to orient the blades in a vertical position during periods when the unit is upwind when the wind commences. A pendulum pitch control mechanism is improved by orienting the pivot axis for the pendulum arm at an angle to the longitudinal axis of its support arm, and excessive creep is of the synthetic resin flexible beam support for the blades is prevented by a restraining cable which limits the extent of pivoting of the pendulum during normal operation but which will permit further pivoting under abnormal conditions to cause the rotor to stall.
Cheney, Jr., Marvin C. (24 Stonepost Rd., Glastonbury, CT 06033)
Wind turbine trailing edge aerodynamic brakes
Five trailing-edge devices were investigated to determine their potential as wind-turbine aerodynamic brakes, and for power modulation and load alleviation. Several promising configurations were identified. A new device, called the spoiler-flap, appears to be the best alternative. It is a simple device that is effective at all angles of attack. It is not structurally intrusive, and it has the potential for small actuating loads. It is shown that simultaneous achievement of a low lift/drag ratio and high drag is the determinant of device effectiveness, and that these attributes must persist up to an angle of attack of 45{degree}. It is also argued that aerodynamic brakes must be designed for a wind speed of at least 45 m/s (100 mph).
Migliore, P G [National Renewable Energy Lab., Golden, CO (United States); Miller, L S [Wichita State Univ., KS (United States). Dept. of Aerospace Engineering; Quandt, G A
Combination wind turbine generator and solar hot water system
This demonstration combined two renewable sources of energy, wind and solar, to meet the needs for a hot water system and electrical generation. A new and unique wind blade design called a Helical Wind Turbine was used. The solar hot water system used was commercially produced. The project has demonstrated that wind generators are feasible in Harford County, Maryland.
J. L. Jr
Individual pitch control of wind turbine based on loads estimation
The use of wind energy for generating electricity has been constantly and rapidly increasing over last few decades and this growth is expected to continue. In order to enable even greater role of wind energy in power production wind turbinespsila sizes and rated powers must increase. As wind turbines grow in size they are subjected to extreme loads and fatigue
M. Jelavic; V. Petrovic; N. Peric
Identification of wind turbine model for individual pitch controller design
The use of wind power has been increasing rapidly over last few decades and according to all predictions this trend is likely to continue. At the same time need for better cost effectiveness of wind power plants has stimulated growth in wind turbinespsila size and rated power. As wind turbines grow in size they are subject to extreme structural loads
V. Petrovic; M. Jelavic; N. Peric
Real-time simulation of BLDC-based wind turbine emulator using RT-LAB
A novel wind turbine emulator (WTE) based on a torque controlled Brushless DC (BLDC) motor is presented, which can emulate the steady-state and dynamic characteristics of an actual wind turbine. Variable wind speeds, turbine inertia and torque oscillation caused by tower shadow and wind shear are all considered in the construction of the actual wind turbine model and the torque
Honghao Guo; Bo Zhou; Jichen Li; Fangshun Cheng; Le Zhang
Maximum power extraction from a small wind turbine using 4-phase interleaved boost converter
This paper describes a 4-phase interleaved boost converter in a small wind turbine application. The boost converter is placed between the wind turbine and the load and is controlled to extract the maximum power from wind turbine. The boost converter duty ratio adjusted, based on the wind speed and rotor speed values, so that the wind turbine would be operated
Liqin Ni; D. J. Patterson; J. L. Hudgins
How I Home-Built an Electricity Producing Wind Turbine
This site has step-by-step instructions on how to build a wind turbine with parts you can purchase from the hardware store and e-bay. The website includes photographs and text which illustrate how to build the wind turbine.
Davis, Michael
Impact of wind turbine controller strategy on deloaded operation
In the past, wind turbines were only required to provide limited ancillary services and they could inject as much power as they wanted in the grid. Nowadays the impact of wind turbines is no longer negligible. Therefore, many system operators have put in place grid codes which require renewable energy sources support the power system and provide ancillary services. These
P. Venne; X. Guillaud
Experimental demonstration of the Diffuser Augmented Wind Turbine concept
The Diffuser Augmented Wind Turbine (DAWT) is one of the advanced concepts being investigated to improve the economics of wind energy conversion systems (WECS). Very compact diffusers using boundary layer control have been examined experimentally. Small scale model testing with screens and centerbodies to simulate a real turbine was used to choose a baseline diffuser configuration. This design is a
B. L. Gilbert; K. M. Foreman
Stochastic Models for Strength of Wind Turbine Blades using Tests
The structural cost of wind turbine blades is dependent on the values of the partial safety factors which re- flect the uncertainties in the design values, including statistical uncertainty from a limited number of tests. This paper presents a probabilistic model for ultimate and fatigue strength of wind turbine blades especially considering the influence of prior knowledge and test results
Henrik Stensgaard Toft; John Dalsgaard S°rensen
Wind turbine load reduction by rejecting the periodic load disturbances
For the cost per kilowatt hour to be decreased, the trend in offshore wind turbines is to increase the rotor diameter as much as possible. The increasing dimensions have led to a relative increase of the loads on the wind turbine structure; thus, it is necessary to react to disturbances in a more detailed way, e.g. each blade separately. The
I. Houtzager; Jan-Willem van Wingerden; Michel Verhaegen
Lightning protection for wind turbine blades and bearings
The protection of wind turbines from lightning damage is increasingly important as they increase in size and are placed in locations where access to carry out repairs may be difficult. As blades are the most common attachment point of lightning, they must be adequately protected. In addition, the passage of lightning current through wind turbine bearings introduces a risk of
Ian Cotton; Nick Jenkins; Krishnan Pandiaraj
Effects of Wind Turbine Farms on ATC Radar.
The UK Government supports the introduction of wind turbine farms as part of its alternative energy strategy. However, Ministry of Defense (MoD) guidelines restrict planning consent for wind turbine farms within line of sight (LoS) from Primary Surveillan...
Radar-Cross-Section Reduction of Wind Turbines. Part 1.
In recent years, increasing deployment of large wind-turbine farms has become an issue of growing concern for the radar community. The large radar cross section (RCS) presented by wind turbines interferes with radar operation, and the Doppler shift caused...
B. C. Brock J. A. Paquette J. J. McDonald P. G. Clem S. E. Allen W. E. Patitz
Wind turbine electromagnetic scatter modelling using physical optics techniques
A software programme has been developed at EMRAD to model the Radar Cross Section (RCS) of complex objects such as wind turbines. The model is based on Physical Optics simplifying the computational complexity of the model. Initial validation experiments show encouraging results. The model predictions can then be used to compute the effects of wind turbines on nearby radio systems.
H. S. Dabis; R. J. Chignell
Failure Modes and Effects Analysis (FMEA) for wind turbines
The Failure Modes and Effects Analysis (FMEA) method has been used to study the reliability of many different power generation systems. This paper now applies that method to a wind turbine (WT) system using a proprietary software reliability analysis tool. Comparison is made between the quantitative results of an FMEA and reliability field data from real wind turbine systems and
H. Arabian-Hoseynabadi; H. Oraee; P. J. Tavner
Assessment of lightning stroke incidence to modern wind turbines
An assessment of lightning stroke incidence to modern wind turbines will be presented in this paper. Wind turbines present tall isolated objects, often located in regions with high thunderstorm activity. This leads to their high lightning incidence, which means that they tend to get struck by lightning very often, compared to other structures. This fact, combined with the intense grow
Petar Sarajcev
Control of wind turbine generators connected to power systems
A unique simulation model based on a Mode-O wind turbine is developed for simulating both speed and power control. An analytical representation for a wind turbine that employs blade pitch angle feedback control is presented, and a mathematical model is formulated. For Mode-O serving as a practical case study, results of a computer simulation of the model as applied to
H. H. Hwang; H. V. Mozeico; L. J. Gilbert
General review of the MOSTAS computer code for wind turbines
The MOSTAS computer code for wind turbine analysis is reviewed, and techniques and methods used in its analyses are described. Impressions of its strengths and weakness, and recommendations for its application, modification, and further development are made. Basic techniques used in wind turbine stability and response analyses for systems with constant and periodic coefficients are reviewed.
Dungundji, J.; Wendell, J. H.
Wind turbines emulating inertia and supporting primary frequency control
The increasing penetration of variable-speed wind turbines in the electricity grid will result in a reduction of the number of connected conventional power plants. This will require changes in the way the grid frequency is controlled. In this letter, a method is proposed to let variable-speed wind turbines emulate inertia and support primary frequency control. The required power is obtained
Johan Morren; Sjoerd W. H. de Haan; Wil L. Kling; J. A. Ferreira
Fault ride-through capability of DFIG wind turbines
This paper concentrates on the fault ride-through capability of doubly fed induction generator (DFIG) wind turbines. The main attention in the paper is, therefore, drawn to the control of the DFIG wind turbine and of its power converter and to the ability to protect itself without disconnection during grid faults. The paper provides also an overview on the interaction between
Understanding the unbalanced-voltage problem in wind turbine generation
Most wind turbines are equipped with line-connected induction generators. Induction generators are very attractive as wind turbine generators due to their low cost, ruggedness, and the need for little or no maintenance. At constant frequency, the induction generator operates in a small range of speeds and, therefore, it operates with a small range of slips with respect to synchronous speed.
E. Muljadi; D. Yildirim; T. Batan; C. P. Butterfield
Representing wind turbine electrical generating systems in fundamental frequency simulations
Increasing numbers of wind turbines are being erected. In the near future, they may start to influence the dynamics of electrical power systems by interacting with conventional generation equipment and with loads. The impact of wind turbines on the dynamics of electrical power systems therefore becomes an important subject, studied by means of power system dynamics simulations. Various types of
The paper presents the design procedure of a permanent magnet generator for a 20 kW wind turbine prototype. This work has been developed in the frame of a research project funded by the General Secretariat for Research and Technology of Greece concerning the design and construction of a gear-less wind turbine for both autonomous and interconnected operation with the electrical
S. A. Papathanassiou; A. G. Kladas; M. P. Papadopoulos
Using partial safety factors in wind turbine design and testing
This paper describes the relationship between wind turbine design and testing in terms of the certification process. An overview of the current status of international certification is given along with a description of limit-state design basics. Wind turbine rotor blades are used to illustrate the principles discussed. These concepts are related to both International Electrotechnical Commission and Germanischer Lloyd design
W. D. Musial; C. Butterfield
DOE/NASA Lewis large wind turbine program
An overview of the large wind turbine activities managed by NASA is given. These activities include resuls from the first and second generation field machines (Mod-0A, -1, and -2), the status of the Department of Interior WTS-4 machine for which NASA is responsible for technical management, and the design phase of the third generation wind turbines (Mod-5).
Thomas, R. L.