Major cable supplier Nexans reached three significant milestones in September – its cross-linked polyethylene (XPLE) insulated HVDC design has now fully qualified for 320 kV applications, while type testing at 525 kV has just been successfully completed. At the same time the company has qualified the first 600 kV mass impregnated cable with a paper-based insulation.
Nexans' focus on HVDC cables is driven by the growing interest in the world for HVDC power links.
Nexans has responded by developing three cable technologies ‘to provide TSOs with the most appropriate solutions for their HVDC links’ namely XLPE insulation, mass-impregnated paper insulation and superconductors.
Its XPLE cable qualified for land and submarine applications at 320 kV through the combination of type tests and long-term pre-qualification tests, all carried out according to international standards. The same technology principle was applied to achieve a step up in voltage, which led to the successful completion of a type test at 525 kV.
Mass impregnated HVDC cables are generally preferred for long-distance submarine transmission at the highest voltages. Recent examples include the 100 km subsea element of Canada's 900 MW interconnection being constructed between Labrador and Newfoundland. The same cable design is also being used for the Skagerrak 4 interconnector between Denmark and Norway.
This kind of cable has been used for a large number of power transmission links operating at voltages up to 525 kV and a power rating exceeding 800 MW per cable. Nexans has now qualified the first 600 kV mass impregnated cable with a paper-based insulation providing a power transmission capacity of 1900 MW in a bipole configuration. The company believes that such cables are highly competitive for the future realisation of high-power HVDC transmission systems.