The Influence of Physical Parameters on Space Charge Characteristics in Cable Insulation Under AC Electric Field

The space charge dynamic behavior and accumulation are important contributions to the formation of electrical trees, as recognized by cross-linked polyethylene (XLPE) cable insulation under alternating current electric stress. In this article, in order to investigate the reasons for the charge accumulation phenomenon revealed by experiments under ac stress, a bipolar space charge transport model with symmetrical and asymmetrical parameters is built under ac stress. The charge accumulation mechanism is analyzed based on the variation of space charge density with different voltage application time and voltage phase. The effects of each major physical parameter are simulated and analyzed, respectively. The results show that there is no obvious space charge accumulation with the transport model under symmetrical physical parameters. However, asymmetrical parameters in the transport model result in different motions between positive and negative charges, which greatly enhances the charge accumulation. Each main parameter has an influence on charge accumulation in different perspectives and extents. The applicability of the simulation model with asymmetrical parameters is evaluated by comparing experiment and simulation results. This study contributes to the understanding of space charge generation mechanism under ac voltage and serves as a basis for improving the stability of XLPE electric power cables.