Research On Single-phase Grounding Fault Section Location Method Based On AGM Curve Energy

At present,China’s distribution network is mostly low-current grounding systems,including systems that are not grounded at neutral points or grounded through arc suppression coils.Single-phase grounding faults have a high probability of occurrence in the distribution network,accounting for about 80%of the total number of faults.If the failure is not dealt with in time,the faults may expand into more serious situations such as inter-phase short circuits,affecting the safety and stability of the distribution network.In this paper,a single-phase grounding fault section location method based on Adaptive Global Mean(AGM)energy is proposed for the fault characteristics of significant difference in the trend of transient zero sequence current waveform on the opposite side of the fault point,and it is verified through simulation and experiment that the method can accurately identify the fault segment under different system operation modes and fault conditions.The specific research work has the following points.(1)Based on the single-phase ground fault zero sequence equivalent network,the transient zero sequence currents on the same side and different side of the fault point are studied theoretically and simulatively,and the characteristics of large differences in transient zero sequence current trends on the different side of the fault point are obtained.Through simulation analysis,it is obtained that under different operating states and fault conditions of the system,the trend of transient zero sequence current on the opposite side of the fault point varies significantly,and this fault characteristic is not affected by the fault conditions and always exists.(2)A fault segment location method based on the energy of the AGM curve of the transient zero sequence current is proposed.The method firstly uses the pole-symmetric mode decomposition to obtain an adaptive global mean line reflecting the post-fault transient zero sequence current waveform trend,and then uses its energy difference to describe the difference degree of the post-fault transient zero sequence current waveform trend,and constructs a criterion to determine the fault zone according to the magnitude of the energy difference between adjacent detection points.The method does not require uploading the sampling data of the whole period to the master station,which reduces the communication requirements,and the constructed criterion does not require setting a threshold value,which is simple and easy to implement.(3)Simulation and experimental validation of the proposed method are performed using a distribution network simulation model established by Matlab/Simulink and an experimental model established by using a laboratory distribution network physical simulation platform.The results show that the proposed method can accurately identify the fault zones under different system operation modes and fault conditions,and has certain anti-interference property.