On-Line Contingency Selection Algorithm for Voltage Security Analysis

Presented in this paper is a new concept in formulating a performance index for contingency selection concerning voltage security anlaysis. The performance index is defined as a second order vector norm in the voltage space. Two types of voltage limits, alarm limit, and security limit, are introduced. Each axis of the voltage space is normalized by the difference between these two limits. Contingency cases in which the performance indices are greater than 1.0 are selected as severe cases and can be ranked in order or severity. This type of normalization results in a clear definition of security. Rapid contingency simulation is performed using essentially noniterative linearized models. Test results indicated reasonable contingency selection and ranking for both a sample test sytsem and an actual power system.