发电机机端电压互感器匝间短路导致定子接地保护动作分析

近年来,发生了多起发电机机端电压互感器(TV)一次绕组匝间短路导致定子接地保护动作的事故,增加了故障排查的工作量。文中推导了TV一次绕组匝间短路时,对地相电压和线电压的计算公式,得出故障发生时定子对地零序电压升高,对地电压最高相(比正常时有所升高)的下一相即为故障相,以及线电压没有明显变化的结论,并通过现场录波数据验证了理论分析的正确性。文中还提出了利用注入式定子接地保护的电阻判据区分TV一次绕组匝间短路和定子接地故障的思路,为快速排查故障提供参考。

Operation Analysis of Stator Earth Protection Due to Voltage Transformer Inter-turn Short-circuit at Generator Terminal

A number of accidents of stator earth protection action due to inter-turn short circuit fault of voltage transformer''s primary winding at generator terminal have happened in recent years, increasing the workload of troubleshooting. The formulas for phase voltages and line voltages relative to ground are deduced during inter-turn fault of voltage transformer''s primary winding. The corresponding conclusions are obtained that, during the fault, the phase next to that of the zero-sequence voltage of the stator rising and being highest(relative to normal time)to the ground is the fault phase, and that the line voltage is constant. The correctness of theoretical analysis is verified by field recorded data. This paper also puts forward the thought of using the criteria for resistance of stator ground fault protection with injection voltage to distinguish between inter-turn short circuit fault of voltage transformer''s primary winding and stator ground fault, providing a reference for rapid trouble shooting.