Development of High Voltage Direct Current Extruded Cables

High voltage direct current (HVDC) extruded cable is one of the key power devices for realizing the flexible interconnection of large power grids, the power transmission with long distance and large capacity, and large-scale utilization of renewable energy. We review the progress of HVDC extruded cables from aspects including the development of insulating materials, accessory technologies, testing methodologies, cable measuring and detecting techniques as well as main projects worldwide. In particular, we analyze recent studies on DC conductivity and space charge properties of various insulation materials for DC cables, type and prequalification tests of DC cable systems as well as measurement methods of space charge and DC partial discharge on full-size cables. Moreover, we put forward urgent questions need to be solved in HVDC extruded cable technology, for instance, studying DC conductivity and space charge characteristics as well as long-term aging behavior and mechanism of existing insulation, developing new materials for higher voltage DC cables and accessories, optimizing the structural design of cable accessories, improving the space charge measurement and DC partial discharge detection technologies for full-size cables, and revising corresponding standards and regulations for HVDC extruded cable systems. Hopefully, the research will provide a reference for designing, manufacturing, testing, operating, and maintaining of HVDC extruded cables in China.