Abstract
In this paper voltage stability is analysed based not only on the voltage
deviations from the nominal values but also on the number of limit
violating buses and severity of voltage limit violations. The expression
of the actual state of the system as a numerical index like severity, aids
the system operator in taking better security related decisions at control
centres both during a period of contingency and also at a highly stressed
operating condition. In contrary to conventional N – 1 contingency
analysis, Northern Electric Reliability Council (NERC) recommends N – 2
line contingency analysis. The decision of the system operator to overcome
the present contingency state of the system must blend harmoniously with
the stability of the system. Hence the work presents a novel N – 2
contingency analysis based on the continuous severity function of the
system. The study is performed on 4005 possible combinations of N – 2
contingency states for the practical Indian Utility 62 bus system. Static
VAr Compensator is used to improve voltage profile during line
contingencies. A multi- objective optimization with the objective of
minimizing the voltage deviation and also the number of limit violating
bus with optimal location and optimal sizing of SVC is achieved by
Particle Swarm Optimization algorithm.
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