| Among different kinds of equipment in transformer substation, circuit breaker is one of the most essential equipment both from quantity and investment aspects. Circuit breaker plays a dual role in control and protection, so in the maintenance of transformer substation, if there are frequent switching heavy load and failure load cutting, it will increase circuit breaker’s aging process and then give rise to frequent breakdown. Once the breakdown happens, the safe operation of transformer substation even the whole power system will be effected and then lead to high maintenance cost. Therefore, it is very necessary to study circuit breaker’s optimal maintenance strategy to increase the economy and the reliability of circuit breaker’s operation.This paper introduces optimal maintenance strategy based on effective age.Effective age means equipment’s real age. This strategy points out that, after going through several maintenance, the age of circuit breaker will rollback and the increasing speed of failure rate will accelerate, which is more close to the real maintenance situation.In view of the above circumstances, this paper proposes the dynamic “age reduction factor” and “failure rate increasing factor” to describe hazard function’s real situation of circuit breaker after maintenance.First, this paper analyzes the circuit breaker’s reliability and maintenance theory based on the following respects: common fault, basic maintenance method, reliability index, maintainability index and availability indicator. Second, it represents the basic mechanisms of fault and maintenance of circuit breaker, analyzes the Weibull distribution, gets parameter’s solution by maximum likelihood estimation and probability paper method and then analyzes the optimal maintenance age based on minimum cost method and maximum availability method. Then, it proposes the definition of “correction factors” to describe the imperfect maintenance of circuit breaker and analyzes the definition of “age reduction factor” and “failure rate increase factor”. And then it discusses the distribution function of the both factors. Last, the the optimal maintenance model based on effective age can be obtained using the “correction factors” to correct hazard function after maintenance. It also analyze the model from objective function,constraint condition and solution method aspects. This paper verifies the validity of the strategy by simulation analysis. |
