Analysis on the Growth Mechanism of Electrical Treeing in Transmission Cables

Electrical treeing is a defect of cable aging. Partial discharges within the insulation cause local electrical field anomalies and minor distortions, which act as initiation points for the formation of an electrical tree. As the electrical tree grows, it can eventually lead to insulation breakdown. Therefore, it is of practical importance to study the growth mechanisms of electrical treeing in cable insulation. The growth mechanism of electrical treeing in cross-linked polyethylene (XLPE) is analyzed from the perspective of its aggregation structure. Based on the growth morphology and the rate of electrical tree growth, the development process is divided into three stages: initial stage, rapid growth stage, and stagnant growth stage. The rapid growth stage is further categorized into the early and late stages. COMSOL finite element simulation software is used to model the entire to analyze the electric field distribution at each stage. In addition, the influence of carbon particles, varying in positions, sizes, and densities, on electrical treeing is studied to better understand its growth characteristics. The results showed that the electric field distortion is more serious when carbon particles are close to the tip of the needle and the tip of the electric treeing. At the same growth stage, the electric field intensity was negatively correlated with carbon particle size and positively correlated with density. When size and density are the same, the intensity of electric field increases gradually with the development of the growth stage. The effect of carbon particles on the insulation breakdown characteristics is further revealed.