Identification and location method of asymmetric faults in coal mine power network
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摘要: 针对煤矿电网单相接地、单相断线和铁磁谐振这3类不对称故障极易发生误判,现有方法无法准确辨识这3类故障等问题,分析了单相接地、单相断线、工频铁磁谐振故障序特性,得出了序电流在煤矿电网中的分布规律:负序电流只在故障线路和上级电网中流过,非故障线路负序电流为零;发生铁磁谐振故障时电网中不产生负序电流,只有微弱的零序电流。在此基础上提出了一种煤矿电网不对称故障辨识与定位方法:根据负序电流判定铁磁谐振故障、零序电流区分单相接地与单相断线故障,根据负序电流分布系数进行故障定位。仿真结果表明,该方法可准确、可靠地实现煤矿电网单相接地、单相断线和铁磁谐振3种不对称故障的辨识与定位。Abstract: Three asymmetrical faults of singe-phase grounding, singe-phase line breakage and ferroresonance in coal mine power network are easily misjudged, and existing methods hardly identify the three faults correctly. In order to solve above problems, fault sequence characteristics of singe-phase grounding, singe-phase line breakage and power-frequency ferroresonance were analyzed, and distribution laws of sequence current in coal mine power network were obtained, which showed that negative-sequence current only flowed through fault line and preceding power network, while negative-sequence current in non-fault lines was zero , and there was no negative-sequence current and only weak zero-sequence current in power network under the condition of ferroresonance fault. On this basis, an identification and location method of asymmetrical faults in coal mine power network was proposed. The method uses negative-sequence current to judge ferroresonance fault, zero-sequence current to identify singe-phase grounding or singe-phase line breakage fault, and distribution coefficient of negative-sequence current to locate fault line. The simulation results show that the method can identify and locate the three asymmetrical faults in coal mine power network correctly and reliably.
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