Research On Reliability Of Intelligent Substation Protection System

According to the requirements and related plans of China’s power companies to accelerate the construction of new intelligent substations,China will become the world’s greatest amount of intelligent substation,the richest country practice.In the process of development of intelligent substations,a large number of smart devices representing the latest technological concepts have emerged.Substation information gathering,diffusion and information processing methods are facing significant changes.The way of sharing information between devices has changed from stable and reliable cable transmission to network sharing.The internal structure of the protection system has changed from "two layers and one network" to "three layers and two networks".Digitization and networking bring many problems to the stable and reliable operation of the system.Compared with the traditional protection system,the reliability of the new protection system has been reduced.Therefore,the research and analysis of its reliability is necessary.According to the reliability block diagrams of various protections in intelligent substations under different sampling trip modes,this paper establishes fuzzy Markov models.The triangular membership function is used to express the variation range of equipment reliability parameters,which makes up for the shortcomings that only certain values can be used in traditional reliability analysis.Based on the fuzzy Markov model,the differences in the reliability of the protection system under different protection configurations and different picking methods are compared and analyzed,and the weak links are identified.Traditional substation reliability evaluation research pays more attention to the reliability of the secondary system,while ignoring its impact on the primary system.In view of the above-mentioned shortcomings,this article aims at several specific protection system failure scenarios such as protection device malfunction,refusal to act,and intelligent terminal refusal to act,using the minimum path set statutory to analyze the influence of the failure of the protection system on the scope of a power outage of the system equipment.It also quantitatively analyzes its impact on the real-time reliability of the primary system of the smart substation,and proposes measures and suggestions to reduce incorrect protection actionsThe analysis results show that the application of fuzzy Markov model for reliability analysis is more suitable for real working conditions and has stronger adaptability.The real-time power supply reliability of the primary system is highly related to the protection system,and the reliability analysis of the substation should be carried out in conjunction with the primary and secondary systems.