TABLE OF CONTENTS High voltage direct current (HVDC) transmission [1 3] is a major user of power electronics technology. The HVDC technology first made its mark in the early undersea cable interconnections of Gotland (1954) and Sardinia (1967), and then in long distance transmission with the Pacific Intertie (1970) and Nelson River (1973) schemes using mercury arc valves. A significant milestone development occurred in 1972 with the first back-to-back (BB) asynchronous interconnection at Eel River between Quebec and New Brunswick; this installation also marked the introduction of thyristor valves to the technology and replaced the earlier mercury arc valves.
Until 2005, a total transmission capacity of 70,000 MW HVDC is installed in some 95 projects all over the world. To understand the rapid growth of dc transmission (Table 30.1) [4] in the past 50 years, it is first necessary to compare it to conventional ac transmission.
| HVDC link | Supplier | Year | Power (MW) | DC voltage (kV) | Length (km) | Location |
|---|---|---|---|---|---|---|
| Gotland I [#] | A | 1954 | 20 | 100 | 96 | Sweden |
| English channel | A | 1961 | 160 | 100 | 64 | England France |
| Volgograd Donbass [*] | Unknown Russian manufacturer | 1965 | 720 | 400 | 470 | Russia |
| Inter-island | A | 1965 | 600 | 250 | 609 | New Zealand |
| Konti-Skan I | A | 1965 | 250 | 250 | 180 | Denmark Sweden |
| Sakuma | A | 1965 | 300 | 2 125 | B-B [***] | Japan |
| Sardinia | I | 1967 | 200 | 200 | 413 | Italy |
| Vancouver I | A | 1968 | 312 | 260 | 69 | Canada |
| Pacific intertie | JV | 1970 | 1440 | 400 | 1362 | U.S.A. |
