一起主变压器差动保护误动事故的分析

针对一起区外故障引起主变压器差动保护误动的事故,通过对事故中差流成因和两套保护动作不一致开展深入分析,找出事故产生的原因并提出预防措施。分析结果表明:事故原因为区外故障短路电流的非周期分量引起主变压器低压侧 CT 暂态饱和产生差流,而基于波形对称原理的差动保护未能闭锁差流,导致差动误动。所述预防措施可为现场避免此类事故的发生提供可行的解决思路。

Analysis on an accident about main transformer differential protection device misaction

Aiming at an accident of outside regional fault leading to main transformer differentialprotection device misaction,deeply analyzes the causes of bringing differential current and the twosets of protection device action disagreement in the accident,finds out the causes of the accidentand puts forward precaution misaction. The analysis result shows that the cause of the accident isthat nonperiodic component of outside regional fault short-circuit current lead to low voltage sideCT transient saturation of main transformer to come into being differential current,but thedifferential protection device based on wave form symmetrical principle cannot shutting thedifferential current,so caused differential protection device misaction.The precaution misaction canprovide solution for avoiding such accident to happen.