直流接地引起涌流抑制器误动原因分析及改进

Analysis of surge suppressors malfunction by DC system grounding fault and improvement

结合某换流站的500kV站用电变压器进线开关3次误动作实例,介绍了事故的概况,叙述了事故原因的查找过程:检查回路、测试绝缘、更换操作箱插件等方法均未发现异常;通过数字示波器成功地监测到第3次开关跳闸时,各跳闸回路的电压、电流波形,分析波形和涌流抑制器的动作特性后,确定3次事故是由于220V直流系统接地引起的变压器涌流抑制器开入回路误动作而导致开关误跳闸。针对查找出的原因,从提高装置的抗干扰和改进外部设计回路2个方面采取了相应措施,其效果良好。

The improper trips of the transformer inlet feeder breaker in a 500 kV converter station are described and the causes are discussed. No abnormality was found during circuit check, insulation test and operating box module replacement. The current and voltage waveforms during the third trip were recorded by the digital oscilloscope and analyzed combined with the operating characteristics of the surge suppressor. The conclusion is that,the improper trips were caused by the binary input circuit malfunction of surge suppressor during the grounding fault of 220 V DC system. Countermeasures are taken in two aspects：enhancement of device anti-interference capability and improvement of external circuit design.