电树枝起树后电压幅值对生长形貌和局部放电特性的影响

Effect of voltage amplitude on growth morphology and partial discharge characteristics of electrical tree

电树枝在XLPE电缆故障中是一种常见现象,在电缆运行过程中可能会存在电压的波动,然而鲜有报道电树枝起树后电压幅值对其生长形貌和局部放电特性的影响。本文研究了电树枝起树后不同电压幅值下电树枝生长形貌和局部放电特性的差异。结果表明:施加电压越高,电树枝的形貌趋向发展为丛状电树枝,施加电压越低,电树枝的形貌趋向发展为枝状电树枝或单枝状电树枝;在较高电压下的最大局部放电强度试验可用于预测击穿故障,而在较低电压下很难通过局部放电强度预测电树枝的生长;电树枝的放电间隔Δt最大值随着加压时间的增加而变长,放电的间歇性也更加明显,电树枝放电间隔与电树枝的生长联系紧密,当电树枝生长停滞时才有概率出现局部放电的间歇性,电树枝处于生长时局部放电几乎不会停滞。

Electrical tree is a common phenomenon in XLPE cable fault, and there may be voltage fluctuation during cable operation. However, there are few reports on the influence of voltage amplitude on the growth morphology and partial discharge characteristics after electrical tree is initiated. In this paper, the difference of growth morphology and partial discharge characteristics under different voltage amplitudes after electrical tree initiated was studied. The experimental results show that when the applied voltage is higher, the electrical tree morphology tends to develop into a cluster tree, and when the applied voltage is lower, the electrical tree morphology tends to develop into a dendritic tree or a single branched tree. The maximum partial discharge intensity test at higher voltage can be used to predict breakdown fault, but it is difficult to predict the growth of electrical tree at lower voltage through partial discharge intensity. The maximum discharge interval of electric tree becomes longer with the increase of voltage applied time, and the intermittent discharge is more obvious. The discharge interval of electric tree is closely related to the growth of electrical tree. The intermittent partial discharge occurs only when the growth of electrical tree is stagnant, and the partial discharge hardly stagnates when the electrical tree is growing.