负荷变压器差动速断保护区外故障误动原因分析及对策

摘要

Differential instantaneous protection sets for fast fault clearing when serious fault happens inside a transformer and the general percentage differential protection may be no longer in force.Differential instantaneous protection maloperation is a big problem in actual engineering application.This maloperation is caused by low-pressure side current transformer saturation which happens in a load transformer such as the high-voltage house service operating transformer.For a case of external fault maloperation of differential instantaneous protection for high-voltage house service operating transformer,it is based on an analysis of the saturation characteristics of the current transformer to research the causes of differential relay maloperation. Countermeasures have been proposed to solve maloperation of differential instantaneous protection by using differential instantaneous protection made up of power frequency differential relays.Moreover,this maloperation is caused by low-pressure side current transformer saturation with high-voltage house service operating transformer and load transformer of direct distribution line.%差动速断保护是为了在变压器内部发生严重故障，一般的比率差动保护可能误判为涌流而失效时能够快速切除故障而设置的，高压厂用变压器(简称高厂变)等负荷变压器因低压侧区外故障电流互感器(TA)深度饱和引起的差动速断保护误动问题一直是实际运行中的难题。针对一起高厂变差动速断保护区外故障误动的案例，通过对 TA 饱和特性的分析，找到了常规差动速断保护误动的原因，提出了用工频量差动速断保护来解决高厂变和直配线路负荷变压器因低压侧 TA 饱和引起的差动速断保护误动问题的对策。