Electric Field Simulation Analysis of $\pm 525 \text{kV}$ HVDC Cable GIS Termination Under Different Temperatures

The electric field distribution is determined for the structural design, material characteristics and operating conditions of the HVDC cable GIS termination yet gets complicated when coupled with temperature due to highly temperature-dependent conductivity of insulation. A simulation model of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm 525 \text{kV}$</tex> termination is established based on COMSOL software, and the electric field distribution characteristics inside the termination were systematically analyzed at ambient temperatures of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-40^{\circ} \mathrm{C},-20^{\circ} \mathrm{C}, 0^{\circ} \mathrm{C}, 20^{\circ} \mathrm{C}$</tex> and 40° C. The effect of temperature on the electric field distribution at the gas-solid interface between SF6 and epoxy resin, and the solid interface between epoxy resin and silicone rubber was investigated, and the related mechanism was analyzed, considering the different current. The dynamic transfer process of electric field distribution with temperature change is observed. It is indicated that the electric field intensity is significantly dependent on temperature. At the gas-solid interface, the electric field intensity gradually decreases along the axial direction, and presents an evident decreasing trend with the increase of temperature. When the temperature rises to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$40{ }^{\circ} \mathrm{C}$</tex>, the maximum electric field intensity of the gas-solid interface is only <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2.8 \text{kV} / \text{mm}$</tex>. At the solid interface, the electric field intensity also shows a decreasing trend with the increase of temperature, while it gradually increases along the axis at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-40{ }^{\circ} \mathrm{C}$</tex>, and decreases along the axis at other temperature conditions. For DC applications, the research results show that the design and operation of termination ought to pay more attention to the effect of temperature on electric field distribution to ensure the reliability and long-term stability.