主变差动微机保护TA接线方式探讨

对目前成都电业局110 kV内桥接线变电站中主变差动微机保护TA接线方式存在的问题进行了分析,建议进行差动保护电流接线方式设计时,将主变每一侧开关的TA电流分别引至主变保护屏,分别接至对应的屏内小TA,不能在端子上组合成和电流以后再接入屏内小TA,否则发生主变差动保护区外故障,在TA饱和的情况下,差动保护有误动的可能。

The existing problems in wiring schemes of current transformer（TA） used in micorocomputer-based differential protection for main transformer in 110kV substation with internal bridge connection operated by Chengdu Power Supply Bureau are analyzed. According to the analysis, suggestions are proposed that connection d secondary currant circuits of TA installed in the circuit breakers on each voltage side of tranformers should be made separately to the corresponding terminals of the small TA installed in the transformer protection screen, unlike the connection where cunent addition is made by joining the lines at the terminals before connected with the small TA. The mason for such a change is that incorrect protection actuation may occur if TA saturates at the time of external fault.