Study on space charge accumulation characteristics of 320 kV cross-linked polyethylene cable joints

Abstract

High-Voltage Direct Current (HVDC) cable accessories are the key equipment to connect HVDC cables, and also the weak link in the cable system. In order to investigate the transport characteristics of space charge in cable joints, a two-dimensional axisymmetric cable joint model was established using the bipolar charge transport model, and its space charge and electric field distribution were analyzed through numerical simulation. Furthermore, the effects of the trap depth based on molecular chain displacement and temperature field on interface charge distribution of cable joint were compared with the basic model, respectively. The results show that the stress cone root and the top of the high-voltage shield are easy to accumulate space charges, which will lead to electric field distortion. The trap depth based on molecular chain displacement is larger than that of basic model at the insulation interface, which hinders the charge transport. The model without considering the effect of temperature field accumulates less charge, and the electric field and space charge at the stress cone root and the top of the high-voltage shield change gently with time. The above research results can provide a reference for the design and optimization of cable joints.