一起由母线单相接地引发的母差保护异常动作分析

Analysis on an exceptional operation of bus-bar differential protection owing to single-phase grounding on bus-bar

对一起由母线单相接地引发的母差保护异常动作进行了深入研究。在35kV中性点不接地的系统中,母线发生单相接地,母差保护动作,母联开关跳闸,母线其它开关未动。通过对故障录波器的录波数据和系统短路电流流向的分析,得出是异地两相接地短路造成了母差保护动作,由于电压闭锁的设计使母差保护发生了异常动作。

This paper researched an exceptional operation of bus-bar differential protection to find the result was owing to single-phase grounding on the bus-bar. In the 35 kV system of neutral point ungrounded, there was a single-phase grounding on the bus-bar. It caused the operation of bus-bar differential protection, so the bus coupler switch tripped, and other switches on the bus didn＇t operate. Through analyzing wave data and routes of short circuit, it found that it was the different site two-phase grounding that led to the operation of bus-bar differential protection, and the exceptional operation was due to the design of voltage lockout.