摘要
Abstract
To meet the requirements of large capacity and long distance transmissions, in recent years, the process of UHV DC transmission projects accelerates in China, the demand for gas-insulated metal-enclosed transmission line (GIL) becomes urgent. But one of the key barriers is the insulator surface charge accumulation may reduce the surface flashover voltage, so it is necessary to study the surface charge accumulation effect on UHV DC GIL insulator. Therefore, based on the positive and negative ions transport equations in SF6 gas, a simulation model is established to investigate the surface charge accumulation characteristics of insulator in UHV DC GIL test unit of Chinese EPRI. From the simulation results, both positive and negative charges accumulate on the inner surface and the outer surface of the cone-type spacer, but the charge distribution of each surface is different. And the surface charge density is closely related to the magnitude of the applied voltage, when the-800 kV voltage is applied, the maximum positive charge density +19. 64 μC·m-2 and the maximum negative charge density-22. 93 μC·m-2 are on the outer surface and inner surface of the insulator, respectively. Results also show that the negative withstand voltage of the insulator is lower.关键词
特高压直流/GIL/表面电荷/盆式绝缘子/积聚Key words
ultra-high voltage DC/gas-insulated metal-enclosed transmission line (GIL)/surface charge/basin insulators/accumulation
