国产±550 kV直流GIS研发:关键绝缘技术研究OA

Under a long-term unipolar DC voltage,insulation failures at the gas-solid interface remain a critical limiting factor for the development of high-voltage,large-capacity DC GIS.Focusing on the gas-solid interface insulation issues of±550 kV DC GIS basin spacers,we constructed a surface charge measurement platform for real-sized insulators and a charge-induced surface flashover experimental platform.The charge accumulation characteristics of gas-solid interface and the charge-induced surface discharge were investigated.The material modification and structural optimization studies of the insulator were conducted,followed by type test verification.The results reveal that adopting shielding structures,reducing the surface roughness of central conductor,or applying insulating paint can significantly decrease both density and quantity of accumulated charge spots.Homo-charges suppress the surface discharge,whereas Hetero-charges promote it,with a threshold for charge-induced surface discharge identified as 15 μC/m2.The resistivity of the epoxy formulation at 120℃ is 7.45× 1012 Ω·m,representing an 87％increase compared to that of conventional commercial epoxy resin.With refined design criteria for±550 kV DC GIS,the tangential electric field under DC superimposed lightning impulse voltage is ensured to be less than 11.1 kV/mm.