Compact Systems for High Voltage Direct Current Transmission

In response to the changes in the market of transmission of electrical energy, especially by the generation of renewable energies, new solutions for the high power transmission over large distances by high voltage direct current (HVDC) technology are required. Todays underground laying solutions are limited in terms of the operating voltage and the maximum transmission power. Therefore, a new gas insulated Direct Current Compact Transmission Line (DC GIL) for laying underground is being developed. The DC GIL will be based on the technology of the existing AC Gas Insulated Transmission Line (GIL). Because of its significantly higher current carrying capacity of up to 5000 A, the DC variant of the GIL would not only be able to transmit the required amounts of electrical power more efficiently compared to cable in the future grid upgrade; it would also make power transmission routes more environmentally compatible as well as more economical. For the compact connection of HVDC power transmission system, the first +-320 kV Direct Current Compact Switchgear (DC CS) worldwide has been developed for application on DC offshore platforms and for onshore applications with limited space. This new type of switchgear allows a reduction of up to 95 % space for the switchgear, resulting in total HVDC platform size reduction of approximately 10 %.