Numerical Simulation Research for Space Charge Transport in Coaxial XLPE Cables

Space charge accumulation in cross-linked polyethylene (XLPE) cables can lead to a decrease in the electrical performance. The numerical simulation of space charge can explore the interaction and evolution processes between various microscopic particles. In this paper, a bipolar charge transport model used for coaxial cables was established. Then, the charge behaviors were investigated, and the influence of microscopic charge characteristic parameters was analyzed. The results indicate the coaxial structure and temperature gradient can exacerbate the hetero-charge accumulation in the cable's outer semiconductive layer. Meanwhile, the capture effect of the deep traps hinders the carrier transport, leading to an accumulation of homo-charge near the electrodes. The charge accumulation changes the carrier mobility at various positions and the coaxial structure causes the carrier mobility to decrease along the radial direction from the inner to outer conductors, giving rise to a mobility gradient. With increasing mobility, the charge distribution changes from homopolar to heteropolar.