±100-kV HVDC SF₆/N₂ Gas-Insulated Transmission Line

This paper introduces an HVDC SF6/N2 gas-insulated transmission line (GIL) prototype that operates under 100-kV DC application. In the first part, the development history of GIL products over the past 50 years is reviewed. After that, the design concept of the ±100-kV HVDC SF6/N2 GIL is introduced. A GIL prototype was prepared and the DC withstanding voltage test and DC superimposed lightning impulse voltage test were performed. The results show that this GIL prototype passed all the required tests, including hydrostatic test, gas tightness test, thermal cycling test, DC withstanding test, and DC superimposed impulse test, etc. The successful preparation of this product promoted a major step in researches of the DC GIL and the prototype laid a solid foundation for the development of subsequent industrial products.