Mechanism and Suppressing Method of Interface Charge Accumulation in HVDC Cable Accessory

HVDC cable has been widely used with the development of flexible HVDC transmission. Cable accessories are the weakest part of HVDC cables, while the most serious problem of DC cable joint is the uneven distribution of electric field caused by space charge accumulation, which may lead to the ageing and failure of joint insulation, especially at the interface between different materials. In this paper, the progress of the interface charge research of the HVDC cable accessories is discussed, the existing theoretical model and the suppression method of the interface charge are analyzed, and the research trend of the interface charge of the accessories in the future is prospected. The results show that space charges accumulate at the interface between different material are closely related to temperature, applied electric field and working conditions such as polarity reversal, etc.; the Maxwell-Wagners-Sillars theory and bipolar charge transport model are discussed in detail, and the method of using quantum chemical theory to calculate and analyze interface charges is introduced; the methods of interface charge suppression based on geometry design, surface modification, field grading materials and material selection are analyzed and compared.