大型水电机组保护若干问题探讨

Discussion on some problems of large hydroelectric unit protection

对大型水电机组保护的若干实际应用问题进行了探讨,包括中性点多分支不完全引入对发电机后备保护的影响、大型水电机组的转子接地保护方案、高灵敏横差保护与转子接地保护的配合问题、机端断路器开关失灵保护与TPY级CT的配合问题、失磁保护转子电压接入方式等。通过具体分析和现场的运用实践,针对上述问题给出了具体的建议:宜将中性点分支电流全部引入保护装置;失磁保护用转子电压宜采用4～20mA变送器传变或者经分压器降压后接入保护装置。

This paper discusses some practical problems of large hydroelectric unit protection,including the influence of neutral point multi-branch current incomplete lead-in on generator backup protection,the problem of generator rotor grounding protection scheme,the cooperation between generator highly sensitive transverse differential protection and rotor grounding protection,the cooperation between generator circuit breaker failure protection and TPY class current transformer,and the lead-in mode of generator loss-of-excitation protection rotor voltage.By the detailed analysis and real application,some advices are put forward to solve the above problems.Neutral branch current should be completely injected into the protection device;rotor voltage should be switched into the protection device by 4～20 mA transmitter or voltage divider.