Research On Comprehensive Evaluation Method Based On Relay Protection Of Distribution Network

With the rapid development of China’s economy,the growing economy and the rapid expansion of the scale of the power grid,distribution network as an important hub connecting users,generators and transmission network,its importance in the power system is increasing.Due to the long-term neglect of the construction and management of relay protection in distribution network in China,the lagging development of relay protection in distribution network is gradually exposing problems.Therefore,it is of great help to construct a reasonable index system for comprehensive evaluation of distribution network and to study a scientific evaluation method for finding the shortcomings and defects in the relay protection of distribution network.This paper focuses on the evaluation index system of comprehensive evaluation method of relay protection in distribution network.Its main work is as follows:(1)The principle of the evaluation system construction method and the general steps of comprehensive evaluation are elaborated,the basic structure of the evaluation index system used in this paper is introduced,and the typical comprehensive evaluation method used in this paper is introduced in detail.(2)The principle of establishing evaluation index of relay protection in distribution network is explained.Five first-level indexes with relative independence are obtained by combining protection data with fishbone analysis method,and the bottom indexes are selected.Finally,a set of five first-level indexes(reliability,maintenance level,safety and risk,guarantee level and impact of protection scheme)is constructed.The index system of relay protection evaluation for distribution network is presented,and the overall comprehensive evaluation process is given.(3)The horizontal comparison of the case analysis proves the rationality of the impact indicators of protection level and protection scheme,and the four bottom indicators can reflect the advantages and disadvantages of the relay protection scheme.(4)Combining with the actual data of power grid protection in a certain area,the appropriate underlying indicators are selected,and the evaluation index system is empowered by two-to-two comparison method and Delphi;combining with the fuzzy algorithm,the evaluation criteria of the indicators are given,and through the evaluation criteria,the actual data is converted into the score value;finally,the evaluation value and total score of each level index are calculated by the analytic hierarchy process,and the credibility is obtained.High comprehensive evaluation results of relay protection in distribution network verify the scientificity and reliability of evaluation index system.