High Impedance Fault Identification And Analysis Of Distribution Lines

The smart grid is a revolution of the electric power industry and a comprehensivesolution to deal with energy, environment, climate, economy and sustainabledevelopment, which represent the future grid research and development direction.Distribution network power application is an important part of the smart grid and animportant breakthrough of the intelligent network. Power line is the lifeblood of the grid,which related to the normal life of the people and the safe operation of the powersystem. Distribution network lines have multi-branch lines, complex structure, andoperations are complex and variable, which have been more problems in this system,the line of single-phase ground fault in the distribution network is the most failureoccurs, To solve the electricity reliability problems, the fault must be quickly identifyand analyze and removal of the failure so rapid to improve the reliability of gridoperation.High impedance fault is one of the power single-phase ground faults, however,traditional relay protection measures can accurately detect and protect the generalsingle-phase ground fault, but which can not protect high impedance fault reliably,because high impedance fault can’t produce a large amount of mutation and traditionalprotection device can not detect the mutation. There are many hills and mountains andthe terrain is very complex in china, so distribution network lines must through themountain and canyon, which cause insulators, surge arresters and line discharge to thesurrounding branches that cause high impedance fault. Because of the concealment ofthe high impedance fault, it is very difficult to fount fault immediately, but if the faultcan not be found and handled, it can result in more serious power system failure.Therefore high impedance ground fault identification has become an urgent problem tosolve by power sector. At present, the literature on high-impedance fault is stillrelatively seldom, there is no mature theory applied to the analysis of high impedancefault identification. The focus of this project is to explore new methods and new ideasfor high impedance fault identification analysis of the distribution network lines.Collection of domestic and foreign literature, the paper draws on the research ideas ofgood literature, targeted for the power lines of high impedance fault features and faultidentification method. And using the computer simulation technology to verify theproposed method. Read a lot of literature to establish the arc fault of high-impedance model. In thethe model, Rp and Rn are grounding resistance, and DC power Vn and Vp is the voltagewhen the arc discharge. Analysis of the impact of different parameter values on the highimpedance characteristics, select the appropriate parameters for the high impedancefault simulation analysis.The distribution network simulation system based on PSCAD simulation platformis used to simulate different conditions of high impedance faults and normal switchingoperation. Through analysis of the simulation system, collecting the date of thezero-sequence voltage and zero-sequence current under fault conditions, and usingMatlab toolbox to analysis calculation. process date.By simulating the high-impedancefault occurs in different branch line, through simulation analysis and data processing,using the method to analyze the high impedance fault：High impedance fault analysismethod based on wavelet amount of spectrum value. The methods is able to identify andanalysis of high impedance faults under different circumstances correctly, and also candistinguish the capacitor switching and the normal running operation. Simulationthrough a large number of comparative analysis, to verify the validity and correctness ofthe proposed method.