Condition Assessment For High Voltage Circuit Breakers Based On Credibility Theory

The security of electric power system is becoming more and more importantwith the continuous expansion of grid scale. Circuit breakers are important protective devices of electric power system,so we demand a higher working condition of them.The evaluation and analysis on high-voltage circuit breakers become necessary. In order to replace the regular maintenance of high-voltage circuit breakers in the past and to guarantee the safe operation of power grid, it is the key to obtain the current working condition of circuit breakers accurately through a variety of methods, which plays an important role in the scientific management of power grid and the growth of economic benefits.In this paper, present evaluation methods about the working condition of high-voltage circuit breakers are introduced based on the analysis of current condition based maintenance of high-voltage circuit breakers. Besides, credibility theory is introduced to evaluate the working condition of high-voltage circuit breakers.Firstly, parameters about the condition evaluation of high-voltage circuit breakers are analyzed, including five parameters of mechanical testing, electrical testing, breaking wear, leakage testing and another factor respectively.The influencing factors of high-voltage circuit breaker condition evaluation are determined in consideration of the actual operation of high-voltage circuit breakers and the effects of various factors. These influencing factors are used as the evaluation factors of high-voltage circuit breaker condition evaluation model.After the multi-level target decomposition of evaluation factors, the comprehensive condition evaluation model of high-voltage circuit breakers is established on the basis of credibility theory and circuit breaker inner mechanism.Different evaluation factors will affect the assessment of high-voltage circuit breaker condition evaluation. So the weight of each evaluation factor was calculated through the improved AHP method ignoring the consistency test.The subordinate function of evaluation factors is established based on fuzzy mathematics. Finally the credibility condition evaluation of high-voltage circuit breakers is conducted by calculating the credibility evaluation vector.The evaluation method of high-voltage circuit breaker condition based on credibility theory has established an evaluation software, which has a higher accuracy and good application prospect. Through the analysis of the example, it is proved that we can correctly evaluate the operation condition of high-voltage circuit breakers according to the evaluation parameters combined by comprehensive credibility theory evaluation method. Then we can achieve the current working condition of high-voltage circuit breakers so as to judge whether the maintenance of high-voltage circuit breakers is needed and avoid wasting. The method based on credibility theory provides a new thinking for condition based maintenance.