Effect Of Silicone Rubber Electrical Conductivity Characteristic On The Electric Field Distribution In XLPE Insulated HVDC Cable Accesories

As an important component of direct current transmission system, cross-linked polyethylene(XLPE) insulated HVDC cables are more widely used. Due to the uneven electric field distribution in cable joint and terminal, the production of cable joint and terminal become the weakest link in DC cable system. This restricts the construction and development of XLPE insulated high-voltage DC cable lines to some degree. Therefore, to research specific material formulation used for the reinforce insulation in DC cable joint and terminal which provides the material the ability to improve the electric field distribution is of great application value.Nonlinear silicone rubber composite materials used for stress control body in HVDC cable joint and terminal are prepared by adding nonlinear nano-fillers and conductive nano-fillers. Based on the tested conductivity characteristics of the composite materials, simulation models are established to calculate the electric field distribution in HVDC cable joint and terminal. 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 accessories 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.