Real time simulation of a current flow controller for HVDC grid applications

Interconnecting several offshore wind farms using High Voltage dc (HVDC) connections and forming multi terminal HVDC grid are some of the targets set by industry leaders to be achieved in the near future. Researchers have introduced a few methods of power flow control based on either the control of AC/DC converter stations or the connection of new power electronic equipment to the grid. In this paper, the operation and control of an extended three-port IGBT based current flow control (CFC) device suitable for multi terminal HVDC systems is presented. Features and functionalities of the proposed controller including the balancing of cable currents, limiting the magnitude of cable current and current nulling are demonstrated. The proposed three-port CFC is real time simulated using OP4510 real time simulator. Real time simulation studies explore fast dynamic response and the results show that the CFC studied may have a significant role to play in the control a of power flows in multi terminal high voltage DC systems.