Single-phase-to-ground fault protection based on zero-sequence current ratio coefficient for low-resistance grounding distribution network  

作　　者：Jianrui Li Yongli Li Yonghuan Wang Jinzhao Song 

机构地区：[1]Key Laboratory of Smart Grid(Tianjin University),Ministry of Education,Tianjin 300072,P.R.China

出　　处：《Global Energy Interconnection》2021年第6期564-575,共12页全球能源互联网（英文版）

基　　金：supported in part by National Key Research and Development Program of China(2016YFB0900603);Technology Projects of State Grid Corporation of China(52094017000W).

摘　　要：Definite-time zero-sequence over-current protection is presently used in systems whose neutral point is grounded by a low resistance(low-resistance grounding systems).These systems frequently malfunction owing to their high settings of the action value when a high-impedance grounding fault occurs.In this study,the relationship between the zero-sequence currents of each feeder and the neutral branch was analyzed.Then,a grounding protection method was proposed on the basis of the zero-sequence current ratio coefficient.It is defined as the ratio of the zero-sequence current of the feeder to that of the neutral branch.Nonetheless,both zero-sequence voltage and zero-sequence current are affected by the transition resistance,The influence of transition resistance can be eliminated by calculating this coefficient.Therefore,a method based on the zero-sequence current ratio coefficient was proposed considering the significant difference between the faulty feeder and healthy feeder.Furthermore,unbalanced current can be prevented by setting the starting current.PSCAD simulation results reveal that the proposed method shows high reliability and sensitivity when a high-resistance grounding fault occurs.

关 键 词：Low-resistance grounding system High-impedance grounding fault Grounding protection Zero-sequence current ratio coefficient 

分 类 号：TM862[电气工程—高电压与绝缘技术]