Single Phase Grounding Fault Location Technology For Distribution Network With Fast Fault Transfer Device

As a bridge between users and transmission networks,distribution network is closely related to the production and life of millions of people,and is an important part of public infrastructure.With the development of modern electronic technology,communication technology,computer and network technology,how to realize the effective protection and intelligent control of distribution network,so as to transmit electric energy safely,stably,economically and efficiently for users has become a hot research topic of scholars.In recent years,the scale of China’s distribution network continues to expand,arc suppression coil due to the inability to compensate for high frequency and active power components and capacity constraints,more and more are replaced by fast fault transfer devices.The basic principle of the fast fault transfer device is to quickly ground the faulty phase bus in the station to limit the voltage of the faulty phase when single-phase grounding fault occurs in the system,so as to realize arc extinguishing.At present,there are two problems to be solved in the distribution network with fast fault transfer device:1.Due to the fast action of fast fault transfer device,the fault information originally used for fault line selection and location on the line will be covered up after the fault phase bus is grounded,so the traditional method of line selection and location is easy to fail;2.The original fault point state cannot be identified after the action of fast fault transfer device,and there is a problems that the device could ground many times.The fast fault transfer device makes the fault phase bus grounded,so that the change of fault signal before and after the action can be used as the basis for line selection and fault point identification,and the fault information of all lines can be judged on the spot without centralized analysis.At present,with the increasing use of fast fault transfer device in China’s medium voltage distribution network with ungrounded neutral point,the research on comprehensive processing of single-phase grounding fault based on it has great development prospects and is very necessary.In this paper,based on the ungrounded distribution network with fast fault transfer device,the theoretical research and device development of fault line selection,location and original fault point state identification are carried out:1.The method of fault section location by using additional signal generated by fault phase bus grounding is studied.When single-phase ground fault occurs in distribution network with ungrounded neutral point,the fast fast transfer device is put into operation.There are results of successful and unsuccessful fault elimination and the transition resistance influences the result.Before and after the action of arc suppression device,the different changes of zero sequence current amplitude and phase in fault path and non-fault path are analyzed in depth.Combined with the feeder terminal equipment,the criterion of zero sequence current amplitude ratio and phase offset is proposed to identify whether this section belongs to the fault path and realize the local fast fault section location.The fault location process is designed..2.Based on the above line selection results,the amplitude differences of the current at the bus grounding point and the zero sequence current of the fault line are studied when the original fault point is eliminated successfully or not,and the original fault point state identification criterion is analyzed and designed.In the case of successful elimination of the original fault point,the fast fault transfer device is exited quickly.In the case of unsuccessful elimination of the original fault point,the fast fault transfer device is locked,so the action process of the device is improved.ATP/EMTP software is used to simulate the above fault location and fault state identification methods,and the results prove the accuracy and practicability of the proposed fault processing method..3.Considering the configuration of the existing devices in the distribution network,the fault processing system based on the fast transfer of faults is developed.According to the requirements of the devices in the practical application,the hardware and software are developed.The arc extinguishing,line selection and location integration for single-phase grounding fault in distribution network are realized to ensure the quick local location and rapid processing of single-phase ground fault.This will assist the construction and transformation of distribution network and serve the economic and social development.