Novel HVDC Spacers in GIS/GIL by Adaptively Controlling Surface Charges - Insulation Compounding Scheme

The spacer is a challenging part of high voltage direct current (HVDC) gas-insulated switchgear (GIS) and gas- insulated transmission lines (GILs). Based on the charge adaptively controlling strategy verified by our previously published papers, this paper serves as an important step towards further industrialization of charge adaptively controlling spacers. The insulation compounding scheme based on previous researches is focused in this paper. Spacers composed of insulating regions and charge adaptive control regions with different mass fractions of nonlinear materials were prepared. The mechanical properties, as well as the DC and AC surface flashover performance of these spacers were investigated. The results show that the DC surface flashover voltage is greatly reduced using spacers with a pure insulating region and with a doped charge adaptive region. As the doping ratio of the nonlinear material in the insulating region increases, the surface flashover voltage increases remarkably. However, the mechanical stress decreases dramatically when the mass ratio of nonlinear material is beyond 35%. The different doping ratios of nonlinear materials does not make a difference in AC surface flashover voltage. However, these surface flashover values obtained by bowl shaped spacers are much more stable and higher than that of the values measured from traditional cone type spacers at AC. The results in this paper can be a key step and are helpful in further determining the preferred option of the industrial spacer that can be potentially used in HVDC GIS/GILs. Meanwhile, based on the advanced performance, the idea of the novel bowl shape has potentially possibility in the application field of AC GIS/GILs.