Research On Fault Location Method Of Distribution Network Based On ?PMU

With China's social and economic development and industrial structure optimization and advancement,higher requirements are placed on grid power supply reliability and power quality.The distribution network is the end of the power grid,directly connected to the power users.Its reliable and stable operation will directly affect the users' satisfaction in terms of power supply security and power quality.The fast and accurate fault location during the fault can effectively reduce the power outage area and shorten the power outage time of the users,thereby improving the power supply quality and power supply reliability of the power grid.With the rise of Phasor Measurement Units(PMU)technology,the developed distribution network ?PMUs provide high-precision,time-scaled voltage and current phasor signals for fault location methods.With these advantages,this paper mainly conducts the following research.First,based on the fault observable ?PMU configuration,a fault location algorithm based on the dichotomy search method is proposed.The ?PMUs are only installed at the source nodes and load nodes.The fault current component at the fault point is calculated by measuring the current before and during the fault of each ?PMU.In the fault component network,the fault point search is performed on each line based on the dichotomy algorithm.The admittance matrix and the fault current positive sequence component are used to calculate the positive sequence voltage of each ?PMU configuration node.The actual fault point is obtained by minimizing the deviation norm between the actual voltage measurement value from ?PMUs and the calculated value.The proposed fault location method is verified on the IEEE 34 node distribution system in Matlab/Simulink.Under the influence of noise interference and transition resistance,the proposed algorithm can effectively and accurately determine the exact location of the fault.Second,the inaccuracy of individual line parameters will have a certa:in impact on the fault location accuracy.In order to ensure the practicability of the proposed fault location method,an inaccurate parameter circuit identification and a parameter correction method are proposed.Through the measurement of voltage and current at different ?PMU measurement points combined with the topology and line parameters,the voltage of the unmeasured node(without ?PMU)is calculated from at least three[PMUs.From the inconsistent deviation of the obtained voltage values,the inaccurate line is identified.Then,the node voltage equation with parameter deviation is solved to obtain the accurate line parameters.The simulation results show that under the ?PMU fault observability configuration,the proposed method can effectively identify and correct the line parameters error and improve the accuracy of the fault location algorithm.Finally,for the large-scale distribution network,the fault location algorithm's computation time is relatively large.In order to improve the efficiency of the fault location algorithm and reduce the computational scale,an improved fault location algorithm based on the distribution network partition is proposed.First,the topological sort method is used to determine the longest path of the distribution network.Under the condition of meeting the configuration requirements and system scale requirements of the partition ?PMU,the distribution network is divided into several sub-areas,starting from one area,other sub-areas are modeled as equivalent admittance,connected to that area.Then,by injecting the fault current component successively into each node of that area,the voltages at all nodes are obtained.Among all sub-areas,the node with the smallest voltage deviation from actual values,is determined as the end node of the faulty line.Then,the fault location is realized by the dichotomy search for the determined end-point associated branch to reduce the size of the network admittance to the faulty area admittance and reduce the number of search lines,and improve the fault location speed.According to the analysis of IEEE34 node case study,the improved fault location algorithm based on the equivalence of the distribution network partition can accurately locate the fault,and the positioning efficiency is significantly improved compared with the fault location of the original fault location algorithm.