A hybrid algorithm of on-line fault diagnosis

This paper proposes a hybrid algorithm of on-line fault diagnosis, which calls the data of breakers, protections and digital recorders by layer for diagnosis. Breaker tripping information is used first to determine the power failure area that contains fault components. Where after, protection actions information is used to determine the exact fault elements. At last, digital recorder information is used to evaluate protection actions. The analysis on protection information is the main task and character of this paper. There are two steps in processing of protection information. First we find the intersection of regions of acted protections to locate the exact fault elements with rule-based reasoning technique. And then for each element in the suspicious fault components list, the posterior fault probability is calculated as its fault credence degree. Then the elements in the suspicious fault components list can be sequenced by fault credence degree. Theory of evidence is used for calculating the fault credence degree of the suspicious fault components. It is stricter and more reasonable than before. Simulation analyses of the actual systems verify the effectiveness of the algorithm.