The objective of contingency screening and ranking function is to shortlist
a specified number of critical contingencies from a large fist of credible
contingencies and rank them according to their severity. This paper summar
izes the work conducted as part of the EPRI/B.C. Hydro on-line voltage stab
ility project in developing a Contingency Screening and Ranking (CS&R) modu
le. The two methods of Reactive Support Index (RSI) and Iterative Filtering
are derived in this paper and tested on the large scale systems of B.C. Hy
dro and another Major Unnamed Utility. The results obtained indicate that R
SI 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 meth
od is a very fast and powerful CS&R method and is suggested for systems whe
re some misclassification of contingencies can be tolerated. On the other h
and, 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 in
tegrated in the EPRI/B.C. Hydro On-line Voltage Stability tool.