母线差动保护传动引起的220 kV线路误跳闸事故的分析与防范

Analysis and Prevention of a 220 kV Line Mistrip Accident Caused by Bus Differential Protection Transmission

某220 kV变电站内第二套220 kV母线差动保护某次更换后,断路器传动试验过程中发生了某220 kV线路误跳闸事故。首先,通过分析故障录波得出事故的直接原因为对侧误接收远方跳闸信号而误跳线路。其次对事故发生前所有的安全措施进行了复盘。最后,通过检查两套保护装置和操作箱的远方跳闸回路接线情况,并对电流变化量进行计算,得到事故的根本原因是在对第二套母差保护进行校验时未退出第一套线路保护的远方跳闸压板,导致远方跳闸信号通过第一套线路保护误发至对侧。针对该事故开展的分析具有一定参考价值。

This paper reports an in-depth study and cause analysis focused on the accidental trip of an actual 220 kV line during the circuit breaker transmission test after replacement of the secondary 220 kV busbar differential protection in a 220 kV substation.First it gives the direct cause of the accident by analyzing the fault recording,which was determined as an undesired trip due to opposite side mistakenly receiving far trip signal.Then it performs a re-check over the safety measures before accident occurrence.Finally by examining the remote trip circuit wiring of the two sets of protection devices and operation boxes,and calculating the current variation,it concludes that the accident originated from failure in disconnecting the remote tripping platen of the first line protection when verifying the second set of bus differential protection,which resulted in remote trip signal being mistakenly sent to the opposite side through the first set of line protection.The analysis for this accident can provide useful information for coping with relevant cases in future.