500kV变电站35kV母差保护电流极性测试探讨

Smart test on current polarity of the transformer for 35kV bus differential protection in 500kV substation

随着电力系统的不断发展和电网结构不断完善，在越来越多新建的500kV变电站中，35kV母线上都开始配置母差保护。但是由于一般情况下35kV站用变间隔高、低压侧CT变比太大，站用负荷很小，因此造成站用变在投运过程中，无法通过实际带负荷测试站用变在35kV母差保护中的电流极性是否正确，这样给变电站今后的安全运行留下了大大的隐患。本文介绍一种简单的方法解决这个问题。

With the continuous development of power system and improvement of grid structure, in an in- creasing number of new 500kV substations, bus differential protection is going to be installed at 35kV bus. However, because 35kV station interval is high, transformation ratio of CT in low pressure side is too large, station load is too small, as a result, when the substation transformers put into operation, whether current polarity of actually test substation type transformers with load is correct or not, it can not through, so that it left the huge risks to the future safe operation of the substation. This paper describes a simple way to solve this problem.