Research On Reliability Evaluation Method Of Protective Equipment And Software Design

Protective equipment is the first line of defense to ensure the security and stability of the power system.Thus,to evaluate the reliability of protective equipment accurately and display corresponding maintenance suggestions is of great significance to increasing the reliability of protective equipment and ensuring the safety of power grid.In the paper,the reliability evaluation method of protective equipment is studied in the perspective of the failure characteristics of relays.Moreover,on the basis of the protective equipment operation status data,condition evaluation index set for protective equipment is established,and the status of protective equipment is evaluated to provide a reference basis for condition maintenance.Firstly,based on the analysis of the basic data source and distribution characteristics of relay protection reliability,a protection data collection scheme for protective equipment is designed.Moreover,the collected data is deduplicated and supplemented,and the effective information can be extracted and saved,which provide data base for the subsequent reliability evaluation of protective equipment.Secondly,Aiming at improving the accuracy of the model in the reliability evaluation of protective equipment,a new approach to estimate the parameters of the Weibull distribution model with integrated mean-rank method and the least square method is presented.It overcomes the shortcoming that the mean-rank method only considers the position of each data truncation point,and does not take into account the impact of the length of each failure interval on the analysis result.Based on pretreatment of fault data and defective data of protective equipment,the shape and scale parameters of the Weibull distribution are estimated with the mean-rank method and an improved mean-rank method respectively,and the reliability function and the failure-rate function are obtained and analyzed.Thirdly,to improve the condition evaluation accuracy of protective equipment,a method based on the variable weight-ridge distribution function is proposed.Firstly,the main influencing factors of the protective equipment operation level are analyzed.A new index is supplemented,and the condition-evaluation index set for protective equipment is further improved.Secondly,the extremum processing method is utilized to standardize the indices.Subsequently,the fuzzy analytic hierarchy process and entropy weight method are employed to determine the combination weight coefficient,and then the variable weight principle is introduced to adjust the weight coefficient of each index.Meanwhile,the semi-ladder and semi-ridge membership function distribution model is selected and compared with the triangle distribution model.Finally,the weighted average operator is selected to evaluate the state of protective equipment,which can provide a scientific and reasonable reference for condition maintenanceFinally,based on Access database,the relay protection reliability evaluation and state maintenance system is developed by C# language.The system mainly evaluates the reliability of protective equipment from two angles of data statistics and data dynamic analysis,and realizes the condition-based maintenance of protective equipment.It is with friendly and simple interface,good compatibility and expansibility.