Location Method For Single Phase-to-ground Fault In Closed-loop Medium Voltage Distribution Network

With the rapid development of society and economy,the society’s demand for electricity is more urgent,and the requirements for power quality are becoming higher and higher.At present,China’s power transmission grid has developed into a multi-power closed-loop network structure operation with high reliability,but the closed-loop network in distribution nerwork is still in its infancy,and the existing single-power closed-loop type such as "hand in hand" is mostly used.The research on distribution network faults is mainly focused on the section location and fault distance estimation of radial lines.The improvement of positioning in the closed-loop network operation mode will help to fundamentally improve the reliability of the distribution network.However,while promoting,it also brings some new problems,which are mainly reflected in:the uncertainty of the zero-sequence current flow direction of the small-current grounding steady-state fault under the operation mode of the network,and the problems applicable to the fault location method of radial lines.For this reason,this article mainly focuses on single phase-to-ground faults,including zero-sequence circuits of bolted and resistive grounding faults,in three neutral grounding situations of distribution networks:1.The segment positioning method based on the phase-to-amp ratio method is researched,and the existing fault indicators and other equipment of the distribution network line are used for local judgment.The instruction results are uploaded to the master station,which can be combined with the system topology.Realize the fast fault section location under the new ring network operation mode.2.Relying on the actual engineering project,comprehensively considering the configuration of the existing devices in the distribution network,a single phase-to-ground fault zone locating device for the distribution network based on the closed-loop network operation mode was developed,and the hardware was designed to meet the needs of the device in practical applications And software development to ensure the rapid positioning of the single phase-to-ground fault section of the distribution network,assist the construction and transformation of the distribution network,and serve economic and social development.