Analysis and improvement of the analytic model for fault diagnosis of power systems

After analyzing the inherent defects of the current analytical model of fault diagnosis reviewed in the paper, an improved model that can fully analyze principles of fault diagnosis is presented. In the improved analytical model, a fault hypothesis — normal or abnormal state of the suspected fault elements, along with the malfunction of protective relays and circuit breakers, is regarded as logic variables, and the principles of relay protection configuration and the rules of circuit breaker operation are absolutely analyzed into a set of logic equations. This is the so-called absolute analytical model, an improved version of the current model. Each solution of the improved model is represented as a mode of fault information (living states of the equipments + action and malfunction of the protective relays and circuit breakers). The optimal solution can be obtained by the optimization technique with a priori knowledge and current information from the alarms received. The improved analytical model has been tested by several examples.