Surface Flashover Phenomena and Contributory Parameters in Oil‐Pressboard Composite Insulation System Under DC Voltage

ABSTRACT During the operation of HVDC transmission systems, the oil‐pressboard insulation of converter transformers is constantly subjected to combined AC and DC voltages. The DC voltage component can easily lead to charge accumulation and induce surface flashover. To investigate the development process of surface flashover in oil–pressboard insulation under DC voltage and its influencing factors, this paper establishes a two‐dimensional simulation model using finite element simulation software to study the electric field and charge distribution characteristics of oil–pressboard composite insulation systems. Using the established model, the paper analyses the influence of voltage, gap distance and electron mobility on the surface flashover development process.