High Voltage Direct Current (HVDC) offers a range of technical, environmental and economic advantages over High Voltage Alternating Current (HVAC). Over long distances HVDC is a more attractive technology as it is more efficient and has lower electrical losses compared to AC. HVDC is the only viable technology for long distance subsea cable routes due to technical limitations of AC cable technology.
The inherent controllability of a HVDC line, due to fast and accurate power electronic control, is a major advantage of HVDC. With the ability to provide constant power as well as a range of other control functions, HVDC has become a very important technology in improving the stability, reliability and transmission capacity of power systems.
Demand for long distance transmission is increasing, as sources of renewable energy are generally located far from populous areas were electricity demand is high. All over the world, HVDC is enabling the connection of more renewable energy sources to the grid, replacing conventional power plants and leading to reductions in carbon emissions.