Research On The Electric Field Distribution Of Accessories Of HVDC Cable Based On Finite Element Analysis

Compared with AC transmission,HVDC transmission has a lot of advantages such as long transmission distance,large transmission capacity and low loss etc.HVDC accessories is an important part of HVDC system,its design and development is extremely important.Under the condition of HVDC steady state operation,the electric field distribution is inversely proportional to the electrical conductivity in the insulation structure of cable accessories.In order to improve near the stress cone structure,the nonlinear conductivity electrical conductivity of the reinforced insulation material silicone rubber composites are used to improve the electric field distortion,so that the maximum electric field appears at XLPE.In this paper,modified silicone rubber and pure silicone rubber produced by cable factory are used as reinforced insulation of cable joints.The DC conductivity of two materials at different temperatures and electric fields is tested.The dielectric constant and dielectric loss tangent of silicone rubber are measured by high voltage capacitor Cilin bridge.The conductivity and dielectric constant of modified silicone rubber are higher than those of pure silicone rubber.COMSOL multiphysics simulation software is used to simulate the electric field of the cable joint.The influence of the insulating material,the angle and length of the stress cone and the thickness of the high-voltage shielding tube on the electric field distribution of the high-voltage cable joint is analyzed.The results show that the change of the length of stress cone and the thickness of high-voltage shielding tube has little effect on the electric field distribution inside the cable joint.With the increase of the angle of stress cone,the tangential electric field between the main insulation and the reinforced insulation interface of the cable increases gradually.The modified silicone rubber can make the electric field insidethe cable joint uniformly distributed,and the cable joint structure can be optimized by adjusting the elevation angle and length of the stress cone and the thickness of the high voltage shielding tube.It can provide data reference for the future flexible DC transmission project of State Grid Corporation of China.