Completing the Circuit: Integration of Offshore Wind Farms into the Grid using High Voltage dc Technology

High-voltage (HV) dc transmission has been utilized since the 1950s to interconnect ac systems that are asynchronous or to provide additional transmission capacity within a synchronous zone. Much of this infrastructure is based on online commutated converter technology. Modern HVdc technology is moving toward voltage-sourced converter (VSC) technology, which provides additional functionality over the online commutated converter, including the independent control of active and reactive power as well as the capability of creating a sinusoidal voltage at its ac terminals when energized at its dc terminals, and is thereby able to provide electrical power to a dead ac system.