UHF discharge characteristics of foreign objects in GIS and multi-physics coupled reliability optimization strategies

To address the problems of insulation degradation and equipment failure in Gas Insulated Switchgear (GIS) caused by partial discharge induced by internal foreign objects, as well as the low positioning accuracy and delayed response of traditional operation and maintenance methods, this study investigates the mechanism of foreign object-induced failures and key technologies for multi-dimensional reliability enhancement. We systematically analyzed the UHF discharge characteristics of typical defects, revealing the regulatory laws of foreign object size, air gap parameters, and the SF6 medium on discharge spectra and energy distribution, and clarifying the flashover risk of 5–8 mm metal particles. A sound-electricity joint detection method and a two-level positioning system were proposed, with the foreign object discharge signal capture probability reaching 85%. Structural optimization schemes such as trapezoidal reconstruction of shielding rings were put forward, and related devices were developed; combined with insulation optimization measures, the surface flashover voltage increased by 23%. A multi-physics field coupled experimental platform was built, and a hybrid model integrating foreign object risk for dynamic insulation health index and life prediction was established, with the remaining life evaluation error of ≤±10%. This study forms a full-lifecycle reliability enhancement technology system, providing support for GIS “zero-leakage” operation and maintenance.