绝缘纸中空间电荷效应的模拟研究

Simulation of space charge effect in insulating paper

为明晰空间电荷对油纸绝缘纸板中电场强度的畸变效应、纸板老化状态与空间电荷的作用机制,采用双极性载流子输运模型,对不同老化状态的绝缘纸板中的空间电荷特性进行数值模拟。对于同一老化状态下的绝缘纸板施加直流电压时,纸板中会出现同极性电荷积聚现象,且正极性电荷的分布范围较负极性显著变窄;随着加压时间的增加,纸板中的电场畸变率呈增大趋势。当绝缘纸板老化程度加深时,其陷阱密度和深度均会增加,致使空间电荷在纸板的近电极侧大量积聚,进而削弱纸板和电极边界处的电场强度,加剧纸板内部的场强畸变;且绝缘纸板老化愈严重,空间电荷对电场的畸变作用愈突出,使得绝缘纸板加速老化,容易诱发绝缘击穿故障。研究结果可为变压器油纸绝缘设计提供参考。

In order to clarify the distortion effect of space charge on the electric field intensity of insulation paperboard and the effect mechanism of degradation degree of paperboard and space charge,the bipolar carrier transport model is adopted to simulate characteristics of space charge in insulation paperboard with different degradation degree. When DC voltage is applied in the insulation paperboard with the same aging condition,the mono-polar charge accumulates in the paperboard,and the distribution range of positive polarity charge is significantly narrower than negative polarity. When the applied voltage time increases,the electric field distortion rate in paperboard also increases. When the degradation degree of insulation paperboard deepened,both the trap density and trap depth increase,resulting in a large amount of space charge accumulate in the paperboard adjacent both electrode sides,which further weakens the electric field intensity at the boundary of the paperboard and the electrode,and intensifies the field intensity distortion inside the paperboard. Moreover,the more serious the deterioration of insulation paperboard,the more prominent the distortion effect of space charge on the electric field. The degradation of paperboard is accelerated. On the other hand,the breakdown fault of paperboard is prone to be induced. The conclusions provide reference for the design of oil-paper insulation.