抄録
A correct and rapid inference is required for practical use of expert system for fault section estimation in power systems. This paper proposes a new model based expert system for fault section estimation using colored and timed Petri nets. The Petri nets simplifies the inference procedure very much because it can represent the causalities among faults of power system components, protective actions of relays and circuit breakers and can also represent the operating states of these protective devices explicitly, or more precisely whether a relay has been actuated correctly or falsely etc. In addition, time sequence information on actuated relays and tripped circuit breakers can be handled by using the colored and timed Petri nets. Therefore, the operating states of relays and circuit breakers can be inferred more correctly. Petri nets are suited for parallel processing so well that there is a possibility of reducing the inference time considerably. In the proposed system, the inference is executed by setting the initial states in the Petri nets using the information on the actuated relays and the tripped circuit breakers and then operating the Petri nets. Several test cases have been tested using a prototype system on Macintosh computer using Object Common Lisp and good results have been obtained.
