Novel HVDC Spacers by Adaptively Controlling Surface Charges – Part I: Charge Transport and Control Strategy

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A spacer is a challenging part of high voltage direct current (HVDC) gas-insulated substations and gas-insulated transmission lines. This paper proposes a novel design of HVDC spacers by self-adaptively controlling the surface charge. The paper briefly reviews dielectric modification methods that aim to limit surface charge accumulation. A novel design of HVDC spacer is introduced that is based on the concept of adaptively controlling surface charges using nonlinear materials, and its surface charge control and regulation abilities are investigated. The surface charge accumulation and decay properties of the novel spacer are compared to a downsized spacer. The results show that the proposed model spacer can restrict surface charge accumulation in the charge adaptive control region of the spacer. Doping the nonlinear material can facilitate surface charge decay in the charge adaptive control region when the electric field exceeds a threshold. These positive results represent a new idea of designing a suitable spacer to avoid surface flashover in HVDC SF6apparatus.