Advanced contingency selection methodology

This paper describes the development and implementation of contingency ranking and selection algorithms, as part of a power system security assessment program. The work concentrates on performance-index-based algorithms and uses a contingency control variable for precise contingency representation. The ranking is based on the value of the sensitivity of the performance index with respect to the contingency control variable for each outage. The computation of the sensitivities is performed using the very efficient co-state method. Furthermore an approach for improving the accuracy of performance-index-based contingency ranking methods is introduced. This approach is based on state rather than performance index linearization with respect to the contingency variable and it provides more accurate results in contingency ranking and selection. The effectiveness of the proposed method in identifying critical contingencies is illustrated using some small test systems. The ultimate goal is to achieve fast and accurate contingency selection, without having to solve the full load-flow problem for each contingency (as is the current utility practice).