Compact High Voltage Direct Current Gas-insulated Systems

The technology of high-voltage direct current transmission (HVDC) for long-distance transportation of huge energy amounts has made its way also for grid access of offshore windfarms and interconnectors between different countries. A gas-insulated design of HVDC systems for converter and transition stations can give advantages compared to air-insulated systems. The technology of HVDC GIS helps to decrease the footprint of converter stations of onshore and even more driven by cost saving aspects of offshore installations. Using insulating gas under pressure, space requirements of HVDC switchgears can be reduced by (70 ... 95) %. Since both, overhead lines and underground transmission by HVDC power cables or HVDC gas-insulated lines are expected in the upcoming HVDC links and overlay networks, HVDC GIS may also be applied at transition stations between different transmission media to minimize the footprint of these stations, while integrating all relevant functionalities in gas-insulated technology. Beside the space saving aspect, the HVDC gas-insulated switchgear assemblies provide high reliability and availability, since there is no direct impact of ambient conditions like dust, salty air, ice or rain to the high-voltage parts. Today it is possible to provide gas insulated HVDC systems. The manufacturer of HVDC GIS systems has already successfully concluded the component tests and a prototype installation test.