1. A method of controlling a power generating unit, the method comprising: receiving, at a computing device, a first load demand set point signal indicating a first desired output of the power generating unit; determining, via the computing device, a control signal to be used to drive the power generating unit to operate to generate power according to the first load demand set point; periodically performing a state estimation while the power generating unit is ramping to reach the first load demand set point to obtain a current state estimation of the power generating unit; receiving a second load demand set point signal indicating a second desired output of the power generating unit before the power generating unit has reached the first load demand set point; using the current state estimation to calculate, via the computing device, a modified control signal for a use in driving the power generating unit to operate to generate power according to the second load demand set point based on the second load demand set point signal; and using the modified control signal to operate the power generating unit to drive the power generating unit towards the second desired output specified by the second load demand set point signal.