Method Of Small Current Grounding Fault Location For Distribution AutomatiOn System

More than80percent of the fault in the distribution network is single-phase grounded fault, however, China's distribution automation system is seriously flawed in dealing with the small current fault's location due to the reason of technology which is a potential threat for the safe operation of power grids. This paper focuses on the problem of current fault section location in the neutral point non-effectively grounded system.The most important issue of current fault location for neutral point grounding system is the collection and processing of the weak and unstable fault current signal to capture the fault information. This paper presents with the method of distribution network wide-area zero-sequence-phasor measurement, which sets the zero sequence current measurement points on the distribution network line based on wide-area zero-sequence-phasor measurement, to overcome the differentiation of the fault current magnitude and phase in the line, when the single-phase grounded fault occurs in the distribution grid, fault path from the point of failure the most recent zero-sequence current measurement points can obtain the amplitude and accurate measurement of the fault current characteristics of information, providing support for fault location.In this paper, the idea that integration of arc and fault line selection and fault location is proposed. Changing can make the mutation of current on the fault path, the author imported the concept of equivalent to calculate the difference of the current when the arc suppression coil off Degree vary, and accomplished the phasor criterion to Identify the small current fault information based on mutation method and wide-area phasor measurement. This article makes full use of the function of the shunt reactor combined arc suppression coil, to realize the fast and effective regulation of the arc suppression coil off Degree, to provide a reliable technical basis for the identification of low current fault information.In this paper proposed a fault section location theory of the small current based on the distribution network wide area zero sequence phasor measurements. To divide the distribution line section adopted with the zero-sequence phase wide-area measurement point. The introduction of the measuring point adjacency matrix, marking vector of segment starting points and fault path to identify vector is to express the difference of the line fault path and the path of the non-fault circuit branch. For with the power grid line load asymmetry lead to asymmetry run, set the zero-sequence voltage fault thresholdâ–¡, as the basis to determine the neutral point non-effectively grounding system with or without a small current failure. Give an algorithm to strike the boundary nodes of the fault interval, to identify the distribution line fault path, calculate the line fault a collection of regional nodes and possible fault slip. The distribution network physical simulation experiments and the hanging net operating results prove the correctness and validity of section location based on the distribution grid wide area zero sequence phasor measurement.Proposed smart state diagnostic methods of small-current fault line selection device based on intelligent diagnostics and artificial intelligence theory, according to the experts'maintaining process of selecting device, fault recorder data and the fault line selection for the record information, to diagnosis error reasons of the selecting device line selection, to give an objective evaluation on-site selecting device quality, reliability and authenticity of the site data of the field devices, to provide technical support for technicians to use and maintain a small current fault line selection device.In this paper, a small current grounding fault type identification method based on the recognition principle of the phase plane theory and wavelet analysis is proposed. Extract the fault characteristics of the different types of small current grounding fault algorithm, to classify them based on the theory and method of pattern recognition, and identify stable Fault, Arc Fault, high resistance arc-type failure, high impedance discharge type failure and gap discharge fault effectively based on the experimental data for the fault recorder, to provide useful information support to find small current point of failure for the line patrol officersDesign and implement the mobile neutral non-effectively grounded grid current fault location system and the neutral non-effectively grounded grid current fault section location system, based on the proposed distribution network wide area zero sequence current phasor measurement fault section location theory in this paper, and the physical simulation results confirms the effectiveness of the proposed distribution network wide-area phasor measurement methods and fault section location system is reasonable. On this basis, the neutral point non-effectively grounded grid current fault section location system designed and achieved has been put into the power grid after review and acceptance with favorable results.