The History of High Voltage Direct Current Transmission

Abstract Transmission of electricity by high voltage direct current (HVDC) has provided the electric power industry with a powerful tool to move large quantities of electricity over great distances and also to expand the capacity to transmit electricity by undersea cables. The first commercial HVDC scheme connected the island of Gotland to the Swedish mainland in 1954. During the subsequent 55 years, great advances in HVDC technology and the economic opportunities for HVDC have been achieved. Because of the rapid development of HVDC technology many of the early schemes have already been upgraded, modernised or decommissioned. Very little equipment from the early schemes has survived to illustrate the engineering heritage of HVDC. Conservation of the equipment remaining from the early projects is now an urgent priority, while the conservation of more recent projects, when they are retired, is a future challenge.