直流电压下XLPE电树枝化过程中的局部放电特性  

Characteristics of Partial Discharge During Electrical Treeing in XLPE Under DC Voltage

作　　者：祝曦 林国海 张洪亮[1] 王亚林 吴建东[1] 尹毅 ZHU Xi;LIN Guohai;ZHANG Hongliang;WANG Yalin;WU Jiandong;YIN Yi(Key Laboratory of Control of Power Transmission and Conversion,Ministry of Education(Shanghai Jiao Tong University),Minhang District,Shanghai 200240,China)

机构地区：[1]电力传输与功率变换控制教育部重点实验室(上海交通大学),上海市闵行区200240

出　　处：《中国电机工程学报》2022年第6期2416-2426,共11页Proceedings of the CSEE

基　　金：国家重点研发计划项目(2016YFB0900701)。

摘　　要：为揭示XLPE直流电缆绝缘中电树枝生长与局部放电之间的相关性,该文基于针–板电极结构建立直流电树枝生长与局部放电实验,并通过油浴循环研究温度对直流电树生长与局部放电特性的影响。此外,借助电树枝放电的气–固两相电荷仿真模型,探讨空间电荷与温度对直流电树枝放电的影响机制,揭示直流电压下局部放电驱动的电树枝生长机理。研究表明,当直流电树枝发展至地电极附近时,会因在地电极附近形成的介质阻挡层而“转向”沿水平方向生长。同时,当电树枝沿电场方向生长时,放电强度会增大,而沿垂直电场即水平方向生长时,放电量保持稳定,甚至会出现因新旧电树枝通道的产生与自愈造成放电强度波动。根据气–固两相电荷仿真,表明温度是影响直流电树枝生长的一个关键因素。一方面,温度升高使固体绝缘中电荷的迁移扩散速度加快,针尖处电场增强,增幅达45%;另一方面,高温下电树枝气体通道内电子碰撞电离加剧,带电粒子浓度与放电电流增加,提升了直流电树枝放电强度,加快了直流电树枝发展。In order to reveal the correlation between tree growth and DC partial discharge(PD)in XLPE DC cable insulation,the DC tree growth and PD experiments were established based on the needle-plate electrode structure,and the effect of temperature on the DC tree growth and PD characteristics was studied through oil bath.Besides,a gas-solid two-phase charge simulation model for PD in tree channel was developed to discuss the effect of space charge and temperature on PD during tree growth and reveal the mechanism of electrical tree growth driven by PD under DC voltage.The results showed that DC tree would“turned”and grew along the horizontal direction near the ground electrode,which was related to the dielectric barrier layer formed near the ground electrode.Meanwhile,the growth of tree along the electric field enlarged the PD amplitude,while the extension of tree along the vertical electric field,that was,in the horizontal direction,stabilized the PD,and there were even discharge fluctuations caused by the generation and self-healing of new and old tree channels.According to the charge simulation,it was found that temperature was a key factor affecting the DC electrical tree growth.For one thing,with the increased temperature,the charge migration and diffusion in the solid insulation was accelerated,and the electric field at the needle tip was strengthened by 45%.For another,the electron impact ionization in the gas tree channel was promoted at high temperatures,and the charge density and discharge current were increased,thereby enhancing the PD intensity and speeding up the DC tree growth.

关 键 词：交联聚乙烯 直流电树枝 局部放电 电荷仿真 

分 类 号：TM247[一般工业技术—材料科学与工程]