Multi-Physics Field Simulation of 1100kV GIS SF6 Gas Insulated Composite Bushing

1100kV GIS SF6 gas insulated composite bushing as GIS and external overhead line connecting part plays key role in AC transmission projects. The design of shielding structure for GIS composite bushing is the key step. The determination of SF6 gas pressure in SF6 gas insulated composite bushing and the allowable field strength in shielding structure are discussed in the paper. Design of metal shielding and external insulation structure inside bushing is further determined. Based on this, the 3D finite element simulation model for 1100kV GIS bushing is established. The E-field distribution of the internal metal shielding and the insulation structure is simulated. Moreover, the mechanical stress distribution of bushing is calculated. The calculation results show that maximum electrical stress of metal shielding is about 10kV/mm, potential distribution of composite insulator is close to linear distribution. When loading direction is vertical to the direction of the GIS, the maximum mechanical stress is 11.2Mpa. Under the 1.1 times rated current 6030A, the maximum temperature is 80.1°C. SF6 gas insulated composite bushing has passed the type test. The calculation results in this paper can provide theoretical basis for the external insulation design of composite bushing for HVAC transmission project.