XLPE绝缘高压直流电缆终端内缺陷对电场分布的影响

Effect of the defects inside XLPE insulated HVDC cable termination on the electric field distribution

为了研究以非线性硅橡胶作为增强绝缘的交联聚乙烯(XLPE)绝缘高压直流电缆终端内部存在缺陷时对其电场分布特性的影响,利用多物理场耦合软件仿真研究了无缺陷和含有典型缺陷直流电缆终端内的电场分布规律。研究结果表明:非线性硅橡胶作为增强绝缘具有较强的均化电场分布的能力,使无缺陷直流电缆终端内最大电场分布于电缆主绝缘内;当应力锥安装错位时,电场畸变程度随电缆外屏蔽超出应力锥根部距离增加而增大;当增强绝缘内有气孔时,电场主要集中在气孔附近,且最大电场强度超过空气的击穿场强;应力锥表面微小突起会使其附近处局部电场明显增强。

In order to study the effect of defects inside the crosslinked polyetliylene(XLPE)insulated DC cable termination with nonlinear silicone rubber as reinforced insulation on the electrical field distribu-tion,the electric field distrilDution inside the DC cable termination witli and witliout typical defects is studied by finite element software in this paper.The results shows that tlie nonlinear silicone rubber used as reinforced insulation has a strong capacity to homogenize the electric field and keeps the maximum electric field inside the DC cable termination with no defects located in the major insulation of the cable.When the stress cone is under incorrect installation,the distortion degree of the electric field increases witli the distance that tlie cable external screen extends beyond the root of tlie stress cone.When gas gap exists in the reinforced insulation,the electric field mainly concentrates around the gas gap and the maximum electric field strengtli exceeds the breakdown strengtli of air.The small bulge on the surface of the stress cone obviously enhances the local electric field near the bulge.