Contingency Ranking Based on a Voltage Stability Criteria Index

Reactive power management is an important issue especially in deregulated environment. It will be more crucial when power systems are heavily loaded and voltage collapse may occur. In this paper the objective is to assess the effects of each contingency on reactive power margin in order to rank the contingencies. In order to maintain security of power system in certain level, the impact of each contingency on power system should be estimated. This paper uses the WSCC VSC and base on that it defines a new index with less computational effort. The proposed method is successfully applied to the modified IEEE 39-bus system where significant results are attained.