某500 kV变电站换流变阀侧电压互感器故障机理分析

Analysis of PT Failure Mechanism at Transformer Valve Side of Certain 500 kV Substation

某500 k V变电站融冰兼静止无功补偿装置(SVC)用换流变阀侧电压互感器(PT)发生故障,基于故障PT的解剖试验及系统运行情况的仿真数据,对PT的故障机理进行了分析,产生原因是由于大量的谐波及直流偏置分量,导致PT二次绕组绝缘损坏过热故障。提出通过加装滤波及直流偏置装置或改变PT的接线方式以及提高PT自身的绝缘水平、局部放电水平等措施来抑制故障的发生。

The PT at transformer valve side of certain 500 kV substation used in melting ice and static var compensator was out of order.Based on the simulation data of fault PT dissection test and system operation situation, this paper analyzed the PT failure mechanism. Almost all of the PT failures were caused by a good deal of harmonics and DC bias components, which led to the PT secondary winding insulation damage overheating. This paper proposes that the smoothing and DC bias device should be added to suppress those faults, or else change the PT connection mode, improve the PT self insulation level and partial discharge level etc measures.