Health Assessment Of SF₆ High-voltage Circuit Breaker Based On Improved Fuzzy Analytic Hierarchy Process

SF6 circuit breaker is a very important primary equipment in 500kV extra-high voltage(EHV)substation,which plays an important role in isolating power supply,switching load current and clearing faults to avoid accident enlargement,etc.During the operation of SF6 high-voltage(HV)circuit breakers,the equipment not only has to withstand the electric heating test caused by internal arc striking and extinguishing,but also faces the challenges of external thunderstorm,high temperature,freezing and other environmental factors.As a result,the performance of SF6 HV circuit breakers will gradually decrease with time.When an abnormal operation or failure occurs,it will bring bad influences such as load loss and equipment damage to the power system,which will seriously affect the safe and stable operation of the power system.Therefore,it is necessary to evaluate the health status of SF6 HV circuit breakers,perceive its abnormal state and defects in advance,and provide decision-making basis for operation and maintenance.In this paper,based on the actual operation parameters of SF6 HV circuit breakers in 500kV EHV substation,a health state evaluation method for SF6 high-voltage circuit breakers based on fuzzy analytic hierarchy process is proposed by analyzing various factors affecting the operation state of SF6 high-voltage circuit breaker and the shortcomings of the existing state evaluation methods.The effectiveness is verified by an actual engineering case.This paper mainly completes the following contents:Firstly,the structure and operation principles of SF6 HV circuit breakers are introduced,and the typical faults of SF6 HV circuit breakers and their corresponding fault manifestations are summarized.On this basis,the causes of various faults are deeply analyzed A key state index selection scheme is further put forward,which comprehensively considers the data of on-line monitoring parameters,mechanical test data and operation and maintenance patrol records,where 16 typical evaluation indexes are set for state evaluation of SF6 HV circuit breakers.In addition,aiming at the lack of some key monitoring data in the actual projects of 500kV substations,the corresponding data monitoring methods are put forward to compensate the impact of insufficient data for the state evaluation of circuit breakers.Based on the installation of micro-water,temperature and humidity sensors in the gas chamber and control cabinet of 500kV SF6 circuit breakers in a 500kV substation,the background data uploading setting is improved to solve the problem of online monitoring data lacking.Secondly,aiming at the complex parameters of SF6 HV circuit breakers,a state evaluation method for SF6 HV circuit breakers based on fuzzy analytic hierarchy process is adopted,and the hierarchical state evaluation model of circuit breakers is established.According to the operation parameters,test data and patrol records of SF6 HV circuit breakers in 500kV substation,the state evaluation system is divided into three parts:target layer,factor layer and index layer,and the normalization processing method of index layer data is proposed.Aiming at the problem that the traditional fuzzy hierarchy method doesn’t consider the aging of equipments,the health index is used to optimize the membership function.Its feasibility is verified by an practical example.Finally,on the basis of optimized membership function,considering the complexity and subjectivity of SF6 HV circuit breaker evaluation system,where the consistency test conditions of discriminant matrix are hard to meet and correct,the whale optimization algorithm is applied to solve the state weight.Compared with the particle swarm optimization,it is proved to be more feasible.Based on the penalty-incentive function of the equilibrium function,the weight obtained by the whale optimization algorithm is further optimized,which solves the problem that the single low-weight factor affects the evaluation results.Combining the state evaluation method of comprehensive optimization of membership degree and weight with the engineering practice,the advantages of the proposed method is validated.