Study on surface flashover characteristics of basin-type insulators under low-frequency transmission based on multiphysics coupling

To study the surface flashover characteristics of single-phase basin-type insulators in gas insulated metal-enclosed switchgear （GIS） under low-frequency transmission， an electro-thermal-fluid coupling simulation is employed. Considering the temperature rise due to the skin effect and the temperature-dependent properties of material parameters， this approach calculates the electromagnetic loss， temperature rise characteristics， and surface electric field distribution of the basin-type insulator at different operating frequencies. Based on the time volume theory， the paper comprehensively considers the impact of temperature on the electric field distribution at the gas-solid interface and the generation rate of effective carrier to determine the surface flashover probability of the basin-type insulator at various voltage amplitudes and frequencies. The simulation results indicate that low-frequency transmission can effectively mitigate electromagnetic losses and reduce the maximum temperature inside the GIS enclosure. Furthermore， it offers higher surface flashover voltage for the same insulation configuration. This study provides theoretical support for verifying the insulation levels of gas-insulated high-voltage electrical equipment at different operating frequencies.