Study on Thermal–Fluid Coupling Simulation of GIS Disconnect Switch Considering External Environmental Factors

To address the difficulty of directly measuring the internal conductor temperature and the complex influence of external environmental factors on gas-insulated switchgear (GIS), a three-dimensional thermal–fluid multiphysics coupling model was developed for a 110 kV three-phase common-enclosure GIS disconnect switch. The model incorporates contact resistance heating, natural convection of SF6 gas, wind speed, and solar radiation. The effects of contact resistance and environmental factors on the temperature field distribution were systematically investigated. The results show that an increase in contact resistance significantly raises the conductor temperature, while higher wind speeds effectively reduce the temperature rise of the equipment. Solar radiation substantially increases the enclosure temperature, whereas ambient temperature has little influence on temperature rise. Based on the enclosure temperature rise, a conductor temperature-rise prediction model and a multi-factor correction model were established. Validation results indicate that all models achieved coefficients of determination greater than 0.98, with prediction errors controlled within ±2 °C. The proposed method enables the accurate prediction of conductor temperature under complex environmental conditions and provides technical support for condition monitoring and overheating fault diagnosis of GIS equipment.