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煤矿配电网变压器中性点一般对地绝缘,一旦发生雷击事故,将在中性点产很高的过电压而损坏变压器。因此对雷击下变压器中性点过电压表现特性及引入过电压保护设备后的限压效果研究具有非常大的实际意义。笔者针对山西煤矿集团万家庄煤业35 kV变电站主变中性点对地放电和母线短路故障,调研煤矿配电网防雷现状,结合雷电波过电压传播理论及35kV变压器中性点绝缘性能,分析中性点对地放电事故的原因。并提出线路绝缘子与可调保护间隙的绝缘匹配和、变压器中性点经氧化锌避雷器接地等改造措施。并利用电磁暂态分析程序ATP-EMTP对雷电波过电压侵入变电站情况下变压器中性点经过避雷器接地进行仿真,验证在变压器中性点增设避雷器来限制中性点雷电波过电压的措施是可行的。
Mine distribution network transformer neutral to ground insulation in the event of a lightning accident, will produce high in the neutral over-voltage damage to the transformer. Therefore, it is of great practical significance to study the characteristics of over-voltage of neutral point of transformer and the effect of limiting voltage after introducing overvoltage protection equipment. Aiming at the neutral point discharge and the busbar short circuit fault in the main transformer of 35kV substation of Shanxi Coal Mine Group Wanjiazhuang Coal Mine, the author studies the lightning protection status of the coal mine distribution network, and combines the lightning wave overvoltage propagation theory and the insulation performance of 35kV transformer neutral point , Analyze the reason of the neutral point to ground discharge accident. And the line insulator and adjustable insulation gap insulation matching and transformer neutral point grounding through the zinc oxide arrester and other transformation measures. And the use of electromagnetic transient analysis program ATP-EMTP lightning surge into the substation case of transformer neutral point through the arrester grounding simulation to verify the addition of arresters in the neutral point of the transformer to limit neutral lightning surge voltage is feasible of.