Fault Section Location For Hybrid Feeders Of Distribution Network Based On Information Fusion

Distribution systems in our country are almost neutral un-effectual grounded system (NUGS).This system can reduce ground-fault current, but at the same time it makes it difficult to detect andlocate the fault. So far，although many location methods have been proposed，any single criterionis difficult to satisfy the practical need because of the characteristics of the fault signals and thelimit of technique and the complex running environment. This paper analyzes the drawback to theexisting location methods, studies new algorithms on the basis of predecessors’ researchs, anddeals with the fusion of various criteria to locate the fault section exactly.Based on the analysis of the distribution law of zero sequence current on the lines in NUGSafter single-phase ground fault, a new method for FSL (fault section locating) in small currentpower system called ‘section zero sequence current RMS ratioing method’ is put forward.Steady-state phase method and parallel medium resistance method are improved according to therunning characteristics of isolated neutral system and neutral earthing via arc extinguishing coilsystem to make them adapt to various operating ways and tapyes of line including hybrid feedersconsisting of power cables and overhead lines. The simulation model of10kV distributionnetwork is builded by Matlab toolbox to simulate the fault under different situations and verifythe reliability and feasibility of these improved algorithms.According to the reliability problem of single criterion, a FSL method for NUGS based onfuzzy information fusion using the fuzzy theory and information fusion is proposed. Based ontopology analysis, the section zero sequence current RMS and section phase are calculated, themembership functions of fault measures of every algorithms, their corresponding weightfunction are constructed according to effective domain, and the fuzzy decision reliability ofevery section is calculated to judge the possible fault section. This algorithm enhances theaccuracy of FSL and has more strong adaptability and fault tolerant capability. At last, a singlephase grounding FSL software is designed and developed with Delphi based on object orientedtechnology (OOT) to print the color of the fault section and give an alarm.