Performance assessment and control of power system relaying

The author outlines various reliability assessment and performance monitoring methods for power system protection. Particular reference is made to the approach adopted for protection performance assessment and control in China Light & Power Company Ltd. because of the special `operation when needed´ nature of protection relaying, a probabilistic approach for reliability assessment is adopted with particular emphasis on dependability and security. Various statistical indices are utilized to illustrate the protection equipment performance from the power system and individual relay points of view. It is shown that the method of cause analysis for protection against incorrect operations can pinpoint problem areas for further managerial actions