A model for substation reliability analysis including overload effects

Abstract Markov chains are used in the reliability modelling of substation diagrams. In the adopted approach five states are assigned to each system component, corresponding to normal operation, switching, repair, maintenance and overload conditions. Models are built which include emergencies up to second order. The overload influence on component failure rate and on substation reliability indices is examined. The components mainly studied are the power transformer and the cables insulated with extruded material. The solution is achieved by the minimal tie-and-cut-set method and equations are developed for the various types of contingency. Finally, an example is presented of a distribution substation and two load cycles.