Space Charge Distribution in Submarine Cable Factory Joint Insulation

This passage discusses the high voltage direct current (HVDC) cable employed in submarine power transmission and its weaknesses, specifically the submarine cable factory joint. The recovered process of insulation when manufacturing the joint involves reheating the cable bulk insulation near them, which can cause changes in the dielectric properties and crystalline morphology of cross-linked polyethylene (XLPE). This can result in accumulated space charge and distorted electric field at the interface between the cable bulk insulation and factory joint recovery insulation due to a mismatch of dielectric parameters. The paper discusses the use of both experimental and simulation research to observe the distribution of space charge in submarine cable factory joint insulation. The results show that homo-polarity space charge accumulates more significantly with increasing polarization voltage, and space charge accumulation decreases gradually with temperature rising. Factory joint recovery insulation shows more severe charge accumulation compared to cable bulk insulation, especially at $50^{\circ}\mathrm{C}$ and $70^{\circ}\mathrm{C}$. The maximum amount of space charge accumulation occurs when approaching the interface between the two insulations as far as possible, resulting in severe uneven electric field.