Overall adequacy assessment of an electric power system

Abstract

Reliability evaluation of a complete electric power system, including generation, transmission and distribution facilities, is normally not conducted because of the enormity of the problem. Instead, reliability evaluations of generating facilities, of composite generation and transmission systems, and of distribution system segments alone are conducted independently and the reliability indices obtained for each segment are used to make decisions. These assessments, however, often assume the other parts of the system to be fully reliable and capable of performing their intended function. This kind of analysis therefore gives an optimistic appraisal of the system performance. The paper considers the influence of outages of elements in all parts of an electric power system to obtain a more comprehensive appraisal of the overall system. Some of the factors that affect the overall system performance are highlighted. The relative contributions to overall system indices from composite generation and transmission failures and distribution zone failures are also illustrated. The concepts involved in the reliability evaluation of a complete power network are presented using an educational test system developed at the University of Saskatchewan.