A fuzzy relation based fault section diagnosis method for power systems using operating sequences of protective devices

This paper proposes a novel fault section diagnosis method for power systems based on the fuzzy relation theory. Especially, the proposed method utilizes information on operating time sequences of the actuated relays and the tripped circuit breakers; therefore, the method has the capability of inferring the fault sections correctly even for the complicated multiple faults. The method proposed in this paper is intended to develop an expert system for fault section diagnosis of power systems focusing on utilizing operation sequences of protective devices. The inference is basically executed by sagittal diagrams representing the fuzzy relations. Using operating time sequences of protective devices involving the faults, the method enhances the performance of diagnosing the fault section. In the case studies for real power system, it provided less fault section candidates than without considering the time sequences. As a result, the method reduced the uncertainty and ambiguity for diagnosing the final fault section.