电压周期变化时表面电荷衰减对局部放电特性的影响

Effect of Surface Charge Decay on Partial Discharge Characteristics Under Variable Voltage Cycles

为了研究局部放电(PD)特性随电压周期的变化规律,搭建了表面电荷–局部放电联合测试系统,并测量了不同电压周期下局部放电序列中表面电荷动态分布以及对应的局部放电参数,随后提出了一种计算放电时延的近似方法。实验发现随着外加电压周期的增大,表面电荷衰减愈加明显,放电谱图中放电相位的分布范围会随之发生变化。当电压周期延长到1 s后,电压极性翻转后介质表面无残留电荷,电压过零点附近无反向放电发生,表明残余电荷对外加电场的影响可忽略不计,电压极性反转后的首次放电完全取决于外加电压。最后计算发现,放电时延随着电压周期的增大而增大,且随电压幅值的增大而减小。

In order to investigate the changing regularity of partial discharge（PD） characteristics with voltage cycle, a combined measurement system of surface charge and PD was constructed, and dynamic distribution of surface charge during a PD sequence, as well as the corresponding PD parameters, under variable voltage cycles was measured.Moreover, an approximate calculation method of discharge lag was proposed. It＇s found from the experiments that surface charge decay becomes obvious, and the distribution of discharge phase will change when voltage cycle increases. After voltage cycle extending to 1 s, no residual charges exist on dielectric surface after the polarity of voltage being reversed, and no back discharge near a voltage zero-crossing point can be obtained, indicating that the effect of residual charges on applied field can be ignored; meanwhile, the first discharge after voltage reversal is completely determined by applied voltage. At last, it is found from the calculation that the time lag increases with the voltage cycle, while it decreases with the increase of voltage amplitude.