硅橡胶电导特性对XLPE绝缘高压直流电缆中间接头内电场分布的影响

Effect of Silicone Rubber's Electric Conductance Characteristics on Electric Field Distribution Inside XLPE Insulated HVDC Cable Joints

为改善交联聚乙烯(XLPE)绝缘高压直流电缆中间接头内的电场分布,通过添加纳米填料制备了用于制作电缆接头应力控制体的非线性硅橡胶复合材料。建立了高压直流电缆接头仿真模型,测试了各绝缘材料的电导特性,计算了电缆接头内的电场分布。研究结果表明,70℃时在各场强下未改性硅橡胶的电导率都小于高压直流电缆XLPE绝缘,故电缆接头内的最高场强点位于硅橡胶增强绝缘内,且最大场强远大于电缆本体绝缘的平均场强;以非线性硅橡胶做应力控制体增强绝缘时,超过一定场强后增强绝缘的电导率明显大于XLPE绝缘,保证了电缆接头内最高场强点永远位于XLPE绝缘内,且接近于平均场强。

To improve the electric field distribution inside the intermediate joint of the cross-linked polyethylene（ XLPE） insulated high voltage direct current（ HVDC） cable,nonlinear silicone rubber composite materials for cable joint stress control body are prepared by adding nano-fillers. Based on the tested conductivity characteristics of the composite materials,an HVDC cable joint simulation model is established to calculate the electric field distribution inside the joint. The results indicate that the conductivities of the unmodified silicone rubber under different electric field strength are all smaller than conventional HVDC cable XLPE insulation at 70℃. So the maximum field strength in the cable joint is located in the silicone rubber reinforced insulation and is much larger than the average electric field strength of the cable insulation. When silicone rubber with suitable non-linear conductivity characteristic is used as the reinforced insulation,its conductivity obviously exceeds the conductivity of cable XLPE insulation after the electric field strength exceeds a certain value,thus ensured the maximum field strength is always located in the cable XLPE insulation and close to the average electric field strength.