一起110kV变电站双绕组变压器差流越限异常分析

Analysis of an Abnormal Differential Current Exceeding Limit of Dual-winding Transformer in a 110 kV Substation

变压器正常运行时若变压器差流越限,将引起变压器差动保护差流越限告警,严重时会引起变压器差动保护动作,变压器各侧开关跳闸。本文针对一起110 kV变电站双绕组变电压器差流越限异常情况进行分析,在不考虑电流互感器变比误差、由于电流互感器变比未完全匹配产生误差及变压器励磁电流影响,通过变压器差流计算公式推导,得出双绕组变压器变调档对变压器保护差流影响的结论,并通过变压器不同负荷、不同档位因变压器调档引起差流变化进行算例验证,验证变压器调档对变压器差流的影响的正确性。

If the transformer differential current exceeds the limit during normal operation,it will trigger the exceeding limit warning of the transformer differential protection.In severe cases,it may trigger the operation of the transformer differential protection and the tripping of the switches on all sides of the transformer.An abnormal situation of differential current exceeding limit of a dual-winding transformer in a 110 kV substation is analyzed in this paper.Neglecting the ratio error of the current transformer,the error caused by incomplete matching of the current transformer ratio,and the influence of transformer excitation current,the conclusion of the impact of transformer differential current on transformer protection can be drew through the derivation of the formula of transformer differential current.Through examples of transformer differential current changes caused by transformer gear adjustment at different loads and gears,the impact of transformer gear adjustment on transformer differential current is verified.