雷电冲击电压下油纸绝缘气隙局部放电特性

Partial Discharge Characteristics of Gap Model in Oil-Paper Insulation under Lightning Impulse Voltage

针对变压器在雷电冲击试验中出现局部放电却无法有效诊断分析的现状,构建油纸绝缘多尺度气隙缺陷模型,探究冲击电压条件下局部放电特征。基于油纸绝缘气隙缺陷在雷电冲击电压下的放电特点,将雷电冲击电压作用时间划分为波前时间、半峰值时间、延迟时间和去电荷时间四个阶段,详细阐述了去电荷阶段局部放电驱动机制。结果表明,半峰值时间和去电荷时间内局部放电脉冲极性相反,且在去电荷阶段内脉冲放电无过冲振荡现象,随着气隙高度的增大,延时放电时间延长,平均放电量增加,累积放电量减小,且放电重复率减小。

Aiming at the diagnosis analysis of transformer partial discharge under lightning impulse voltage test, the multi-scale oil-paper insulation gap model is established to study partial discharge characteristics under impulse voltage. Based on the mechanism of partial discharge under lightning impulse voltage, the time of lightning impulse voltage is divided into T1 , T2, T3 and T4. Driving mechanism of partial discharge in the stage of T4 is presented in detail. The results indicate that it is opposite polarity of partial discharge pulse in T2 and T4, but no overshoot oscillation phenomenon in T4 ; it extends the time of T3, the average discharge increases, cumulative discharge decreases and discharge repetition rate decreases with the increase of gap size.