东莞220 kV立新站和跃立站主变压器跳闸分析

介绍了东莞220kV立新站和跃立站3台主变压器跳闸的情况，对同杆双回线路雷击、故障录波、主变压器中性点保护方式和间隙动作原因进行了详细分析，指出：系统单相接地瞬间产生的暂态过电压作用于主变压器中性点，造成间隙放电，导致过流保护动作，主变压器跳闸。针对主变压器在线路重合前跳闸可能造成停电损失，建议延长间隙过流保护动作时限以躲开线路重合闸，避免主变压器不必要的停止运行。

Analysis of main transformer trip-out in 220 kV Lixin Substation and Yueli Substation of Dongguan

Based on the introduction to the trip faults of three main transformers in 220 kV Lixin and Yueli substations in Dongguan,Guangdong,this paper detailedly analyzes lightning stroke process on the same-pole two-circuit transmission lines,fault wave records,protection methods and action cause of gaps at the transformer neutral point. It is indicated that because of the transient overvoltage produced at the moment of single-phase grounding,the gaps discharged and the ensuing action of overcurrent protection resulted in the main transformer trip-out.Then the paper suggests that the action time limit of the gap overcurrent protection be prolonged behind auto-reclosing time of transmission lines to avoid unnecessary trip-out of transformers.