Application aspects of multiterminal DC power transmission

Four practical multiterminal DC systems are described. Two are already in commercial operation: Nelson River (double-bipole four-terminal), and Sardinia-Corsica-Italy (two-terminal monopolar tapped to become three-terminal). Two others are expansions of existing systems and are under construction: Pacific HVDC (high-voltage DC) Intertie (bipolar four-terminal) and Hydro-Quebec/New England (bipolar five-terminal). All of the systems are able to shift to a stable operating point following a disturbance (e.g., loss of a converter station). Application aspects of each system are presented, with emphasis on the attention required to make each system practical.>