一起特高压直流保护预告警事故的分析和对策

Analysis and Countermeasures for a DC Protection Pre-warning Accident in Extra-high Voltage Project

基于发生在普洱换流站的一起由于测量总线故障而导致的跳闸,深入分析西门子直流保护预告警导致测量总线切换的逻辑和时序。西门子直流保护预告警会在保护出口前3 ms发出并切换测量总线,此时如果仅一路测量总线有故障,在切换以后将避免跳闸。但此次跳闸之前总线已经完成切换,本不应该发生跳闸。由于该保护功能中的特殊取平均值的模块,在总线切换后测量值仍然高于门槛值,导致跳闸出口。针对此设计缺陷,提出对保护软件的修改意见以及实际修改措施。

The logic and timing of how Siemens DC protection pre-warning makes TDM bus switchover is deeply analyzed based on a trip caused by TDM bus fault in Puer converter station. Siemens DC protection pre-warning will be sent out 3 ms before protection output and TDM bus switchover is also carried out; if there is just one bus fault, the trip will be avoided after TDM bus switchover. However, the TDM bus has been switched over before the trip which should not have happened. Trip happens because the measured value of the module that takes an average in this protection function is still higher than the threshold value after TDM switchover. For this design defect, modification suggestion about the protection software and actual modification measures are given.