Method of Fault Area ＆ Section Location for Non-solidly Earthed Distribution System

Medium voltage distributions in China use overhead line mainly,and most of them are small current neutral grounding system,single-phase-to-earth faults account for over 80% of the total fault,but most of our country's distribution automation systems do not have the function of locating the small-current-to-earth faults,so that the distribution automation system's efficiency in improving the reliability of power-up has been reduced drastically.The new method of locating the small-current-to-earth faults was studied.First of all a lot of measurement nodes must be fixed on the line to get the feature information of small-current-to-earth fault.And then the algorithm to find fault area boundary nodes(AFFABN) was put forward based on the matrix of adjacent point,the vector of section-starting-point identification and the logo vector of fault path.The physical simulation and practical tests show that the theory of area section location can locate the fault to a section of the line,to narrow the range of lines' maintenance.The AFFABN can also be used to determine the related load switches in a fault zone,to provide information for the line-maintenance and feeder automation.