电压互感器二次回路接地点的分析

Analysis of grounding point for voltage transformer secondary circuit

对一起电压互感器二次回路多点接地导致继电保护装置误动作情况进行分析,验证了电压互感器多点接地造成的危害性。建立了电压互感器二次回路一点接地和多点接地等值电路模型,结合反措要求对现场电压互感器二次回路接地点的检查方法进行总结。提出利用电阻法判断存在多点接地的可能、电流法确定接地点的支路、电压法确定具体的接地点。通过实例验证了检查方法的正确性,同时针对电压互感器二次回路接地点的实际运行情况提出了相应的运行管理要求。

An improper trip of protection caused by the multi-point grounding of voltage transformer secondary circuit is analyzed. The equivalent circuits are established for single- and multi-point grounded voltage transformer secondary circuit and the methods of grounding point cheek are summarized with the anti-accident measures. It is proposed to apply the resistance method to judge the possible existence of multi-point grounding,the current method to determine the branch with grounding point and the voltage method to locate the specific grounding point. Its correctness is proved by practices and corresponding requirements for operational management are presented.