The Influence of Physical Parameters on Space Charge Accumulation and Phase Characteristics in Cable Insulation under ac Electric Field
Résumé
The space charge dynamic behavior and accumulation are important contributions to electrical tree aging, as recognized for crosslinked polyethylene (XLPE) cable insulation under alternating current (ac) electric stress. In this paper, in order to investigate the reason for the charge accumulation phenomenon revealed by experiments under ac stress, a bipolar space charge transport model with symmetrical or asymmetrical parameters is resolved under ac stress. The charge accumulation mechanism is analyzed based on position and amount of charge function of voltage application time and voltage phase. The effects of each major physical parameter are simulated and analyzed separately. It is found that there is no obvious accumulation of space charges with symmetrical parameters. Asymmetrical parameters result in a difference of motion process between positive and negative charges, which greatly enhances charge accumulation. Each main parameter has an influence on charge accumulation from different angles and levels. The applicability of the simulation model with asymmetrical parameters is assessed by comparing experiments and simulation results on space charge. This study contributes to the understanding of space charge generation mechanism under ac conditions and helps improving the stability and operation properties of XLPE cables in power system.
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