Research On Fault Location And Distance Measurement Of Distribution Network With Distributed Generation

The Global Energy Internet is to build a large number of distributed power generation and energy storage equipment to enhance the flexibility and self-healing capacity of the power system,and aims to achieve an energy sharing network based on "renewable energy + Internet".With the continuous development of the global energy Internet,distributed power generation with clean energy as the main source has been rapidly developed due to its low pollution and low energy consumption.However,after the distributed generation(DG)is connected on a large scale,it will have a great impact on the power flow direction,topology,and operation mode of the distribution network,making traditional distribution network fault location methods unable to meet the positioning requirements.Therefore,researching the fault location method of distribution network with DG access is of great significance for improving the safety and reliability of distribution network and promoting the development of DG.This article analyzes the research status of traditional passive distribution network fault location methods and DG access distribution network fault location methods from two aspects: fault section location and distance measurement.The influence of DG grid connection on the distribution network and fault location is analyzed.It discusses how to reform the switch overcurrent threshold so that the switch can distinguish the different fault currents provided by the system power and DG.The new coping methods adopted after the DG grid-connected capacity and quantity are further improved.This paper analyzes the applicability of the currently studied method from different penetration intervals of DG grid-connected,and proposes a fault-locating method based on multi-terminal fault current matching based on the poor adaptability of the fault location method to high-penetration DG access.With the help of DG access,it presents the form of multi-terminal power supply.The contribution of the multi-terminal power supply to the fault point current is analyzed.Through the principle and characteristics of the multi-terminal impedance positioning method,a feature matching function is established to traverse each node in turn.Then,according to the smallest eigenvalue two adjacent nodes realize the identification of the faulty section.At the same time,considering the problem of weak fault signal in the distribution network,it is proposed to establish two indexes of relative distance credibility weight and relative capacity credibility weight to improve the matching function.For the case where the lengths of adjacent lines of the distribution network differ greatly,a section fusion rule is proposed,which can more accurately and quickly locate the section.The simulation results verify that the method can adapt to fault location of distribution network under high penetration DG access.After the section positioning is implemented,it is always hoped that specific fault occurrence points can be found in order to reduce line inspection time and quickly restore power supply.Therefore,starting from the impact of DG access on the voltage sag information of the distribution network,based on the power quality monitoring system,an improved strategy for the optimal configuration of voltage sag monitoring points under DG access is proposed,so that the monitoring point configuration results are not affected.The impact of DG access establishes a basis for fault location with the help of voltage sag information.Then,the function relationship between the positive sequence node voltage and the fault distance is established by the fault distance distribution function.A fault location method based on successive binary search is proposed,and the ranging evaluation function is established by using the ratio of the positive sequence voltage change between the monitoring points.The method can automatically perform successive binary search in the segment,and determine the best number of searches through the evaluation function,avoiding the error caused by setting the convergence threshold,and finally expressing the ranging result by the distance scale value.The simulation proves that the optimized configuration and improvement strategy of the voltage sag monitoring points can effectively avoid the influence of DG on the voltage,so that the ranging results of the successive binary search method are not affected by the DG access and the error is small.