一起220kV变压器差动保护动作行为分析

Analysis of an Action of a 220 kV Transformer Differential Protection

针对一起220kV变压器发生接地故障情况进行了介绍及诊断,分析了变压器差动保护动作特性和故障情况下正序、负序、零序电流情况,分析结果与保护动作报告完全吻合。指出在电动机负荷距离故障点较近时故障后会向故障点返送电流。同时由于△绕组的存在,在单相接地时,装置采集电流中的正序和零序并不相等。

The short circuit fault of a complex 220 kV transformer and its diagnosis is introduced in the paper. The current of positive,negative and zero phase sequence （PS）,and the act characteristic of transformer deferential protection under fault condition are analyzed. Fault types were identified according to recording waveforms at site. And the problems that should be paid attention to that when the fault spot is near the generator. Under single phase grounded the acquired current of positive PS is not equal to current of zero PS because of delta winding.