Simulation of Space Charge Distribution in the Insulation Layer of XLPE HVDC Cable under Different Temperatures

Different temperature distributions may occur in the cross-linked polyethylene (XLPE) high voltage direct current (HVDC) cable insulation layer under different laying methods, laying environments, and load currents, which can result in different space charge distributions. In order to investigate the effects of temperature distribution on the space charge behaviors, a pair of +/- 320 kV XLPE HVDC cables is taken as an example to establish the geometric model. Based on the bipolar charge transport model, the charge distributions in the insulation layer under different load currents are simulated. Results reveal that the accumulated charges arc homocharges and distributed near the injection electrode. The amount of charges near the conductor screen is always larger than that near the insulation screen. As the temperature increases, the amount of charges gradually increases, and the distribution range becomes wider. When the temperatures arc relatively low, the absolute value of the charge density peak close to the conductor screen monotonically increases with time. However, when the temperatures are relatively high, it shows an non-monotonic fluctuation with time. Besides, the charge accumulations are significantly different when the cables are under different voltage polarities.