Research On Single-phase Grounding Fault Location In Distribution Network

With the development of new-type user distribution systems,the manual inspection of buried lines during the transmission process is not very maneuverable,which brings challenges to the fault diagnosis and location of the distribution network.Accurately and quickly locate the fault location and eliminate the fault,improving the safety of electricity consumption and the efficiency of inspection.Among the fault types of distribution network,single-phase-to-ground faults account for more than 80% of all faults.In order to accurately find the location of single-phase-to-ground faults,based on transmission line theory,this paper studies a new method of fault distance location based on standing wave method.The method uses two schemes of multiple frequency points and single frequency multiple measurement points to locate and calculate the fault location.First,this paper summarizes the typical distribution network fault type s and location methods,introduces the fault location device,uses the standing wave method in the transmission line theory to analyze the equivalent model of the fault line,and deduces the relevant formulas and parameter analysis.Secondly,the fault location algorithm based on standing wave is studied.Through the research algorithm,it is found that when a single-phase ground fault occurs,the load end is in a state of completely mismatched or partially matched impedance,and a standing wave will be generated on the transmission line.Therefore,it is necessary to limit the frequency of the signal source.The standing wave on the entire transmission line is monotonic.In this case,the fault distance can be accurately located.Therefore,two fault location schemes,multi-frequency single measurement point and single-frequency multi-measurement point,are designed.Simulink is used to build the fault circuit.Multiple acquisition points are used to simulate and analyze the variation trend of standing waves of the same cable with different signal source frequencies and different cables at the same frequency.Finally,the simulation results under the two schemes are firstly analyzed.After testing the simulation environment,scheme 1 selects two detection poi nts.The distance measurement error of the direct ground fault is within 20 m,and the relative error of the distance measurement is very small.The second scheme adopts the one-point detection method,and the error distance is within 40 m.Both schemes can accurately locate the fault distance;then the experimental environment is set and the parameters are configured,and the scheme one is experimentally verified.Two types of faults,direct grounding fault and grounding through fault resistance,are experimentally analyzed,which verifies the effectiveness of the method in this paper.In actual selection,scheme one and scheme two can be selected according to the needs.Finally,the positioning of the method in this paper is introduced.The process of multi-branch fault,the location accuracy of the method in the case of multi-branch is simulated and studied,which provides a theoretical basis for practical engineering applications.