Research On Networked Protection Technology Of Neutral Non-Effective Grounding System Based On Smart Substation

Single-phase grounding fault is the most common fault type in neutral non-effective grounding system and the fault identification and discrimination is a problem.And bus protection in distribution network is often realized by backup overcurrent protection of adjacent element with low speed.Therefore in this paper,a smart substation technology is adopted,in which single-phase grounding protection and bus protection method of multi criteria is constructed by interactive information and cooperation through the network.This paper discusses the standardization of smart substation information transmission technology and uses GOOSE communication mechanism to realize network protection.After the analysis of functional advantages of networked protection,networked protection scheme of single-phase grounding and bus fault is designed for neutral non-effective grounding system.According to grounding characteristics of neutral non-effective grounding system,the fault identification can be realized by zero sequence full current group power direction.In order to improve the accuracy of fault identification and selection,networked multi-criteria algorithm for single-phase grounding protection is adopted based on steady state parameters,fault identification matrix and fault tolerant algorithm.Protection module of single-phase grounding is built by MATLAB/Simulink to show the accurate identification and strong fault tolerance of networked protection.Based on principle of directional power bus protection,the start-up criterion of bus phase-to-phase short-circuit and the logic of power direction identification are realized.And fault identification and fault tolerant scheme of networked bus protection is constructed,in which power direction information of each interval and the results of pre judgment are shared via GOOSE network.Networked bus protection module is built by MATLAB/Simulink to show the accurate identification,strong fault tolerance and high speed of networked protection.In order to verify the network communication real-time performance of networked protection under fault conditions,a network communication model of smart substation is built by OPNET network simulation software.The different factors which affect the real-time communication are analyzed.And the simulation results show that under the condition of optimal allocation of communication network,the real-time performance of networked protection is good.