Research On Grounding Fault Location Of Distribution Network Based On Traveling Wave Theory

The distribution network has a more complex structure than the transmission network,and has short lines and many branch lines,making fault location more difficult.Since the transient traveling wave generated after a fault in the distribution network propagates along the transmission line,the catadioptric reflection process is complicated.Some fault location methods that are suitable for transmission grids are no longer suitable for distribution networks.The single-ended traveling wave method is difficult to be applied in the distribution network,so it is very necessary to find a simple and effective distribution network fault location method.In this paper,the fault traveling wave is used to locate the fault point.First of all,this paper summarizes the basic ideas and principles of existing distribution network fault location methods by analyzing domestic and foreign literature.Then,starting with the generation of transient traveling waves after a fault in the distribution network,the propagation process of folding and reflection phenomena when traveling waves propagate in the transmission lines is analyzed.The coupling characteristics of threephase in the transmission lines are explained,the basic principles of phase-mode conversion are analyzed,and the modulus characteristics of the upstream wave of the transmission line after a single-phase ground fault in the distribution network are analyzed.Then,the frequency-dependent characteristics of traveling waves are studied from two perspectives: frequency domain and time domain.The thesis analyzes the basic principle of S-transform and its application in identifying the arrival time of traveling wave.According to the difference between the energy and phase of the zero-mode current traveling wave of the fault line and the nonfault line after a single-phase ground fault occurs,define the characteristic energy and the phase coefficient of the fault line and the non-fault line as the criterion for fault line selection.The basic principle of the fuzzy C-means clustering algorithm is introduced,and the fault feature matrix composed of the normalized feature energy and feature phase coefficients is used as an input sample to perform cluster analysis to select the fault line,and do a good job for the next fault location ready.In the synchronous clock environment,the double-end traveling wave method is improved to make it suitable for the distribution network structure with multiple branches and to determine the fault branch and the calculation of the fault distance,and then discuss the fault when some measuring devices are missing positioning method.In the non-synchronized clock environment,the modular time difference method is improved to be suitable for the distribution network structure with multiple branches and the fault branch is judged.Then,the thesis has gave a method for online calculation of the fault distance without the speed of traveling wave.A 10 k V radial complex distribution network model was built by ATP-EMTP software,and simulation analysis was conducted under different fault types,different fault conditions,and different fault distances.The simulation results prove that the two algorithms proposed in this paper have good applicability.The paper has 37 figures,30 tables,and 82 references.