Voltage stability contingency screening and ranking

The objective of contingency screening and ranking function is to shortlist a specified number of critical contingencies from a large list of credible contingencies and rank them according to their severity. This paper summarizes the work conducted as part of the EPRI/BC Hydro on-line voltage stability project in developing a contingency screening and ranking (CS&R) module. The two methods of reactive support index (RSI) and iterative filtering are derived in this paper and tested on the large scale systems of BC Hydro and another major unnamed utility. The results obtained indicate that RSI on its own or in combination with the iterative filtering method can be used for CS&R depending on the acceptable level of misranking. The RSI method is a very fast and powerful CS&R method and is suggested for systems where some misclassification of contingencies can be tolerated. On the other hand, for systems where an exact list of critical contingencies is intended, then the iterative filtering method can be used for screening complemented with another method like RSI for ranking. The latter technique is being integrated in the EPRI/BC Hydro on-line voltage stability tool.