Abstract: By analysis of a generator unit tripping accident caused by main transformer gap protection action as lightning struck on a power transmission line, it was found that the main transformer gap zero sequence protection action was easily caused by lightning strike on transmission lines as power plant connecting to power grid by long single transmission line or on same-tower double-circuit transmission lines. Two methods were proposed to solve this problem: the first was to increase the time setting of main transformer gap zero sequence protection, the other was to take the direct grounding mode of the transformer neutral-point.

摘要： 通过对一起电力线路受雷击造成主变间隙保护动作跳闸停机事件进行分析，阐述了单回出线或同杆架设的双回出线路径经过强雷区且离负荷中心较远的末端电站，单回线或双回线相同时遭雷击引起主变间隙零序保护动作，造成跳闸停机事故，可采用延长主变间隙零序保护动作时限或每台主变高压侧中性点均直接接地方式运行避免。