An expert system for transmission line back-up protection

Abstract

The paper describes an expert system that provides back-up protection for power transmission lines. The expert system evaluates the best possible protection response if the main-protection andor its associated circuit breaker failed to clear the fault. The decision is based on the expert system's knowledge of the topology of the transmission network and the operating response of the distance relays and directional relays protecting the network. The information required from a three zone distance relay is the zones that detected the fault. The information required from a directional relay is whether it operated, this indicates that the fault is in a forward direction. The paper includes results illustrating how the protection behaved when tested using the UMlSTlPSA Power System Simulator.