An approach for explicitly modeling the protective relaying systemin substation reliability evaluation studies

The authors present an approach for evaluating the reliability of a power system substation taking into account its associated protective relaying system. The method employs the technique of minimum cutsets to compute the frequency and duration of a fault with respect to the criterion of continuity of electric service. The protective relaying system is accounted for by explicitly incorporating its elements into a new functional model developed for their associated circuit breakers. The approach was implemented in the form of a computer program and used to compare the reliability of several substation arrangements. These comparisons as well as some details on the practical implementation of the approach are also presented