The first commercial high voltage direct current ( HVDC) installations date back to the 1950s. Nowadays, HVDC technologies are in widespread use worldwide and have long operational experience. ln fact, this technology exhibits characteristics that have already made it attractive over HVAC transmission for specific applications, such as very long distance power, transmission, long submarine cable links and interconnection of asynchronous systems, as well as bulk energy transport. The largest and most recent example of the latter is the installation of a ±800 kV, 7200 MW HVDC link in China.