Research On Fault Location Technology Of Distributed Small Current Ground Fault Based On Fault Passage Indicator

With the development of economy and technology,the scale of the distribution network is expanding year by year.As a hub for electrical energy from substations to power users,whether its power supply is reliable or not directly affects the satisfaction of power users.The neutral point of China's distribution network is widely operated by ungrounded or grounded by arc suppression coils.When a single-phase(small current)ground fault occurs on the line,the fault signal is weak and difficult to detect,and the ground fault accounts for a high proportion of distribution network faults;In addition,the randomness of the load distribution on the distribution network,the complexity of the topology,and the scale of data processing continue to expand,exacerbating the difficulty of troubleshooting.Therefore,the speed of single-phase grounding fault location and the reduction of the time of faults have become higher research hotspots.As an effective method for fault location,fault passage indicator is widely used in fault location of distribution network,but centralized fault location mode requires the reliable coordination and cooperation of fault indicator,communication system,sub-station or main station,with many participating links,the fault processing time is long,the master station is highly dependent,and in the field practical application,there are restrictions on software property rights,system management permissions,and so on.Aiming at the technical problems of current fault passage indicators in the application of small current ground fault location,a distributed small current ground fault passage location method based on fault indicators is proposed.The main research contents of this article are:(1)Two types of low-current grounding methods and characteristics are summarized,the structure and function of the fault passage indicator are introduced,and the basic principles and advantages and disadvantages of centralized and distributed fault location are compared and analyzed,which lays the foundation for the research of the subject.(2)Starting from a three-phase system with a small current ground fault,a transient zero-mode equivalent circuit is established,and the mechanism and specific algorithm for implementing fault location using different fault characteristics are analyzed.(3)Discussed the key technology of distributed fault location using fault passage indicator.A distributed small-current ground fault location system based on fault passage indicators was established,and the structure,startup,and working modes of the system were introduced in detail.The implementation process of distributed fault location was analyzed,and topology identification and modeling,and peer-to-peer communication networking were analyzed.And fault indicator signal acquisition and other key technologies;finally,the process of system segmentation by combining different fault location algorithms and distributed control methods is given.(4)A small current ground fault simulation model was built using the electromagnetic transient simulation software ATP,and the algorithm was verified with Matlab.The on-site discrimination of the fault location system and the fault indicator was tested through field ground tests can be accurately positioned.This article optimizes the fault location algorithm and mode from two aspects,comprehensively improving the practicability of the fault indicator in the location of the small current ground fault section.The research results are of great significance for improving the fault location efficiency of distribution network and improving the reliability of power supply.