Contingency ranking for on-line voltage stability assessment

Voltage stability has become a challenging problem for many power systems. Contingency screening and ranking (CS&R) is one of the important components of on-line voltage stability assessment. The objective of CS&R is to quickly and accurately select a short list of critical contingencies from a large list of potential contingencies and rank them according to their severity. Suitable preventive control actions can be implemented considering contingencies that are likely to affect the power system performance. An effective method for contingency ranking is proposed in this paper. This method calculates the voltage stability margin considering branch outages. Test results based on the IEEE 300 bus power system, a 600 bus power system as well as two utility systems (197 bus and 1254 bus) are presented.