硅橡胶绝缘材料温度及场强依赖特性对XLPE绝缘直流电缆预制接头内电场分布的影响

Effects of temperature and field strength dependence characteristics of silicone rubber insulating material on electric field distribution in prefabricated joints of XLPE insulated DC cables

为选择合适的电缆接头绝缘材料,以改善电缆接头内的电场分布,探究了接头绝缘常用材料硅橡胶的电导温度及场强依赖特性对XLPE直流电缆预制接头中电场分布的影响。首先,针对10 kV电压等级XLPE绝缘直流电缆预制接头结构建立相应的仿真模型。然后,改变硅橡胶材料的电导非线性特征参数,得到对应接头在满载运行状态下的绝缘内电场分布。结果表明:随着硅橡胶材料电导活化能的增大或电导场强依赖系数的减小,接头绝缘交界面处的场强增大,且应力锥根部场强增幅明显;从经济性角度考虑给出硅橡胶与XLPE绝缘材料的电导活化能之比和电导场强依赖系数之比推荐值分别为不高于0.95和不低于0.50,可作为工程上选择确定合适接头绝缘材料的参考。

In order to select an appropriate cable joint insulating materials to improve the electric field distribution in joint,the effects of the conductance temperature and field strength dependence characteristics of silicone rubber of common joint insulating material on the electric field distribution in prefabricated joint of XLPE DC cable were studied.Firstly,a simulation model was constructed according to the prefabricated joint structure of 10 kV XLPE insulated DC cable.Secondly,through changing the conductance nonlinear characteristic parameters of silicone rubber,the electric field distribution in the joint insulation with full load condition was obtained.The results show that with the increase of the conductance activation energy or the decrease of the conductance field strength dependency coefficient of silicone rubber material,the field strength at the joint insulation interface increases,and the field strength at stress cone root increases obviously.From an economic point of view,the recommended values of the ratio of conductance activation energy of silicone rubber and XLPE insulating materials and the ratio of their conductance field strength dependency coefficient are not higher than 0.95 and not lower than 0.50,respectively,which can provide reference for the selection and determination of suitable joint insulating materials in engineering.