刘青松 邓军 池明赫 陈庆国

摘 要：为研究水分对复合电场下油纸绝缘局部放电特性的影响，文章进行了不同含水率下的油纸绝缘结构典型电场下局放特性试验，得到了不同含水率下，油纸绝缘在针-板电极和平板电极中的复合电场局放特性。结果显示，直流分量对局放起始电压及局放量影响较大。不同含水率下局放量均随电压的升高而增大。极不均匀电场下，高含水率下的局放量始终大于或等于低含水率时;均匀电场下，高低含水率下的局放曲线随电压升高出现交叉。经分析得出结论，水分使变压器油电导率增大，易于油水界面空间电荷消散，导致放电量增加。液体介质中的局部放电除经典的介質中气泡缺陷模型外，还可能存在多水滴融合缺陷模型。该缺陷是导致平板电极下高低含水率的油纸绝缘放电曲线出现交叉的主要原因。

关键词：换流变压器，油纸绝缘，复合电场，水分，局部放电

DOI：10.15938/j.jhust.2018.06.015

中图分类号： TM85

文献标志码： A

文章编号： 1007-2683（2018）06-0082-06

Abstract：In order to study the effect of moisture on PD characteristics for oil-paper insulation in complex electric field PD tests with different moistures were carried out under the typical electric-field of oil-paper insulation. The PD characteristics under needle-plane electrodes and plane-plane electrodes were obtained sepratedly in complex electric field with different moistures. The result shows that DC content has a great effect on the inception voltage and PD volume. All the PD volume grow up with the voltage rises under different moisture. In severe non-uniform electric field PD volume in high moisture is always larger than the one in low moisture or equal to it. In uniform electric field the PD curve in high moisture crosses with the one in low moisture.Via analyzing it is concluded that the conductivity in oil is increased by moisture which makes the space charge disappeared easier from oil-water interface and then enhances the PD volume. There may be a bubble combination defects PD model in liquid dielectrics besides a classic bubble defects PD model. The bubble combination maybe the major reason which results in the PD curves in high and low moisture crossing over under plane-plane electrodes.

Keywords：converter transformer; oil-pressboard insulation; complex electric field; moisture; partial discharge

0 引 言

随着电网向远距离、高电压、大容量的趋势发展，直流输电（HVDC）的优越性愈发明显[1]。换流变压器是直流输电系统的核心设备，其可靠与否直接影响了电网的稳定性[2]。大量资料表明变压器事故以绝缘故障为主[3-4]。换流变压器内绝缘与普通电力变压器不同，其阀侧主绝缘除承受交流电压、雷电冲击电压和操作冲击电压外，还承受直流电压、交直流叠加电压以及极性反转电压的作用[5-8]。因此对复合电场下油纸绝缘特性进行研究显得十分必要。……