A enhanced contingency selection method with respect to multiple contingencies for on-line voltage stability assessment

An enhanced sensitivity based contingency selection method for voltage stability assessment is proposed for handling multiple compound contingencies. The original sensitivity based load margin estimation method will lead to missing unstable or severe contingencies. The reasons for inaccurate load margin estimation are analyzed and the handling schemes are given. The proposed method can select correctly the top N (say 100) severe contingencies from a huge number of contingencies, say more than several thousands. It can resolve the difficulty associated with the missing alarm problem. The enhanced method is developed with an on-line VSA tool in a practical 3081-bus power system. Top 100 severe contingencies are selected from more than 2000 multiple compound contingencies which shows the method is very efficient.