Effect of Radial Space Charge Distribution on Electric Field Distribution in HVDC XLPE Cables

High voltage DC (HVDC) cables accumulate space charge and distort the internal electric field distribution during operation. In this paper, the insulation layer of 400kV HVDC cables is taken as the research object. The space charge distribution characteristics of XLPE specimens with different radial positions are studied. The insulation layer is uniformly sliced into thin sheets and divided into three parts: inner, middle and outer. The space charge distribution of XLPE specimens at different radial positions is measured at 30 to 70°C and ±10 to ±30kV/mm electric field strength. The measurement results are taken into the simulation model to calculate the electric field distribution. The results show that the space charge of the inner and outer layers varies significantly with temperature and electric field. The space charge of the middle layer specimen changes with hysteresis. The electric field simulation results show that the electric field intensity is larger at the inner insulation position when no load is applied, and larger at the outer insulation position when full load is applied.