It is of great significance to study the DC electric field of the cable joint to ensure the stable operation of AC cable in DC voltage. In this paper, the typical 10kV AC Cross linked polyethylene (XLPE) cable joint was selected and the thermo-electric coupling simulation model was built. The thermo-electric coupling simulation of the cable joint was carried out under the operating conditions of conductor temperature of 70 º C and DC voltage of 10 kV. When the insulation temperature difference of the cable joint is 20 ℃, the maximum electric field near the high voltage screen tubes of 1.5, 2, 3 and 4 mm thickness are 2.97 MV/m, 2.53 MV/m, 2.19 MV/m and 2.07 MV/m respectively. Moreover, the stress cone curve of the cable joint was optimized. The axial electric field of the stress cone is stable at about 0.04 MV/m after optimization. Therefore, increasing the thickness of the high voltage screen tube can effectively reduce the maximum electric field and the risk of space charge accumulation. Furthermore, the DC electric field distribution in the stress cone region is effectively improved by optimizing the stress cone curve of the cable joint.

DC cable;cable joint;electric field distribution;AC to DC;optimization analysis