Simulation of Influence of DC Pre-Stress on Space-Charge Characteristics of Cross-Linked Polyethylene in Inhomogeneous Field

Space charge is one of the main causes of electrical tree initiation in high-voltage cable insulation. To investigate the influence of DC pre-stress on the space-charge distribution of cross-linked polyethylene (XLPE), a two-dimensional needle-plate electrode model is established in this study. Based on the bipolar charge-transport model, the space-charge distribution characteristics of the needle-plate electrode model under DC pre-stress are simulated and analyzed. The space-charge distribution characteristics are compared with that of the grounded DC electrical tree initiation properties. The work in this study illustrates that the pre-stress time and value affect the space-charge distribution characteristics. There is a certain relationship between space-charge distribution characteristics and electrical tree initiation characteristics. The distribution range of the DC grounded electrical tree is very similar to that of space charge. Both have a similar distribution shape and increased trend under different pre-stress times, and both have an obvious polarity effect.