Fuzzy Approach to Critical Bus Ranking under Normal and Line Outage
  Contingencies
  Identification of critical or weak buses for a given operating condition is
an important task in the load dispatch centre. It has become more vital in view
of the threat of voltage instability leading to voltage collapse. This paper
presents a fuzzy approach for ranking critical buses in a power system under
normal and network contingencies based on Line Flow index and voltage profiles
at load buses. The Line Flow index determines the maximum load that is possible
to be connected to a bus in order to maintain stability before the system
reaches its bifurcation point. Line Flow index (LF index) along with voltage
profiles at the load buses are represented in Fuzzy Set notation. Further they
are evaluated using fuzzy rules to compute Criticality Index. Based on this
index, critical buses are ranked. The bus with highest rank is the weakest bus
as it can withstand a small amount of load before causing voltage collapse. The
proposed method is tested on Five Bus Test System.
