变压器分接头改变对区内单相高阻接地故障灵敏度的影响

评价变压器纵差保护性能优劣的指标之一是其反应高阻接地故障及匝间故障的灵敏度。目前广泛采用的带比率制动的差动保护,在不同工况下,其反应高阻接地故障与匝间故障的灵敏度是不同的。该文分析了变压器分接头调整引起的不平衡电流与区内高阻接地故障形成的差动电流之间的向量关系。指出了分接头升高与降低造成的不平衡电流对保护的灵敏度有不同的影响。最后通过数字仿真对此进行了验证。

Sensitivity shift of the transformer longitudinal differential protection due to adjusting the transformer on-load tap changer

Transformer longitudinal differential protection can discriminate the internal resistance ground fault and the turn-to-turn fault,but the protective sensitivity is low.This paper analyses the vector of the unbalanced differential current caused by adjusting the transformer on-load tap changer(OLTC) and the vector of differential current caused by internal resistance ground fault.It points out that moving up or down the OLTC will increase the unbalanced differential current,but they have different influence on the sensitivity.Finally,an example is given to show the different influence.