Maintenance strategy optimization of metro circuit breaker based on a mixed failure rate

The reliability of the power supply system is critical for the safe operation of metro equipment. How to make a reasonable maintenance strategy in terms of cost and performance control has become an important issue in operation and maintenance practice. At present, metro high-voltage circuit breakers mainly borrow from the equal period preventive maintenance strategy of the railway system. The lack of theoretical basis in setting maintenance periods may happen insufficient maintenance or excessive maintenance, resulting in the problems such as high maintenance costs and long maintenance time. To solve the above problems, an optimized maintenance strategy with unequal periods of the metro circuit breaker is proposed in this paper. Firstly, based on the maintenance data, a mixed failure rate function containing the age reduction factor and the failure rate increase factor is constructed. And a cost function model of metro circuit breakers under reliability constraints is established in a limited time. After that, the optimal preventive maintenance times and unequal maintenance intervals are determined with the minimum maintenance cost rate in the renewal cycle as the optimization goal. Finally, a case study is carried out for the high-voltage circuit breaker of a metro company. The results show that the maintenance cost rate is decreased by about 9.42%, and the maintenance time is reduced by approximately 34.73%, which verify the effectiveness of the proposed maintenance strategy.