Space Charge Behaviours in Cable Insulation under a DC-Superimposed Pulsed Electric Field

Dongxin He (1) , Zhang Tao , Meng Fansong , Qingquan Li , Wei Wang​ , Hongshun Liu , G. Teyssedre (2)

1 Shandong University
2 LAPLACE-DSF - Diélectriques Solides et Fiabilité

When HVDC cables are subjected to a DC-superimposed pulsed electric stress, the pulsed voltage applied facilitates electrical tree generation and breakdown; however, the mechanism involved remains unclear. To study the deterioration mechanism of cable insulation under a pulsed electric field, an experiment on the dynamic characteristics of space charge under a DC-superimposed pulsed electric field was conducted. For this experiment, a pulse time trigger control circuit was developed to accurately measure the change law of the space charge in cross-linked polyethylene samples at the rising and falling edges of the pulsed electric field. The experimental results showed an unusual change law: the space charge density increases with falling voltage amplitude and decreases with rising voltage amplitude. The sudden change in the electric field breaks the balance of the forces acting on the space charge, leading to injection, extraction, and migration. The energy released during these dynamic processes may destroy the microstructure of the insulation material and contributes to the growth of the electrical tree. This study provides an insight on the initiation mechanism of electrical tree in HVDC cables and proposes a strategy to suppress electrical tree initiation.

Domaines: Sciences de l'ingénieur [physics]

Dongxin He, Zhang Tao, Meng Fansong, Qingquan Li, Wei Wang​, et al.. Space Charge Behaviours in Cable Insulation under a DC-Superimposed Pulsed Electric Field. High Voltage, 2020. ⟨hal-03002410⟩