Combined Use of Fuzzy Set-Covering Theory and Mode Identification Technique for Fault Diagnosis in Power Systems

After a fault occurs in a power system, generally some operating information of protective relays and circuit breakers could be obtained. Because protective relays and circuit breakers might improperly operate or fail to operate, and some errors and distortion may exist in data acquisition and communication, as a result uncertainties could be involved in the received information. A fault diagnosis model based on fuzzy set- covering theory and mode identification technique is proposed in this paper. With the fuzzy technology, the above mentioned uncertainties could be dealt with very well. Meanwhile, as the protective relays and circuit breakers may fail to operate in some cases, there are several different operating modes in protective relays and circuit breakers even for a same electrical device failure. Based on the received information, the proposed model could identify the most possible operating mode, and then the information corresponding to a fault hypothesis could be obtained. In the proposed model, the proposed fault diagnosis problem is described as a 0-1 integer programming one, and thus could be solved by the widely employed search technology, i.e., the well-known Tabu search method. The feasibility and efficiency of the proposed model is demonstrated by a sample power system.