500kV变压器局部放电异常的分析及处理

Analysis and Treatment of Abnormal Partial Discharge in 500kV Transformer

针对某台500kV主变在交接试验中进行局部放电试验时出现异常现象,异常信号分布在椭圆基线的第二、四象限的情况,首先通过紫外成像检测排除试验线电晕及外部悬浮干扰,但异常信号仍存在,随后对变压器进行剩磁检测,发现变压器铁芯中存有较多剩磁,然后对变压器进行消磁,铁芯中剩磁明显减少,再次进行变压器局部放电试验,未检测到异常信号,试验合格。此次事件处理过程表明,变压器直流电阻试验后,必须对变压器进行消磁,并检测变压器铁芯剩磁。

Abnormal phenomenon occurred in the partial discharge test of a 500 kV main transformer in the handover test.The abnormal signals are distributed in the second and the fourth quadrants of the elliptic baseline.Inview of this,first by UV imaging detection,the test line corona and external suspension interference are excluded,but the abnormal signal still exists.Then the residual magnetism of the transformer is detected.It′s found that more remanence is stored in transformer cores,and then the transformer is demagnetized.The remanence significantly reduced in the core.The partial discharge test of the transformer is performed again.No abnormal signal is detected.The test is qualified.The treatment process of this event shows that after the transformer DC resistance test,the transformer must be demagnetized and the transformer core remanence must be detected.