500 kV电流互感器例行试验对二次电流回路的影响分析

Analysis of Influence of 500 kV Current Transformer Routine Tests on Secondary Current Circuit by

电流互感器例行试验是变电检修工作的重要内容,该工作对二次电流回路的影响长期缺乏系统性讨论。以500 kV油浸倒立式电流互感器为例,在二次电流回路未断开情况下,定性分析了电流互感器例行试验对二次电流回路的影响。结果表明二次电流回路未断开情况下,在CT根部短接接地将引起二次电流回路两点接地,易引起保护误动;在CT根部短接将引起和电流分流,导致保护误动;CT例行试验过程对二次电流回路几乎没有影响。

The routine test of current transformer is an important part of transformer maintenance in substations,and the effect of this work on secondary current circuit has long been lacking in systematic discussion.This paper takes as an example the 500 kV oil-immersed inverted current transformer,and makes a qualitative analysis of the influence of routine test of current transformer on the secondary current circuit under the condition that the secondary current circuit is not disconnected.The results show that when the secondary current circuit is not disconnected,the short grounding at the CT connection box will cause two-point grounding of the secondary current circuit,which is easy to bring about protection misoperation,that the short connection at the CT connection box will cause the diversion of vector plus current,and result in protection misoperation,and that the process of the CT routine tests has little influence on the secondary current circuit.