Extra high voltage DC extruded cable system qualification

A new 525 kV DC cable system with a power rating range up to powers above 2 GW has been developed for both subsea and underground applications. The 525 kV extruded DC cable system can transmit at least 50% more power over extreme distances than previous solutions (i.e. the 320 kV extruded DC system). The technology enables the lowest cable weight per installed megawatt (MW) of transmission capacity and the higher voltages provide reliable transmission and low energy losses. This system utilizes a new cross-linked polyethylene (XLPE) DC insulation material, an oil- and porcelain-free termination based on wall bushing technology as well as a land joint and a flexible sea joint. The paper describes the product development of the cable as well as the accessories, the extensive testing procedures and the capability of the new cable system.