A DC Current Flow Controller for Meshed HVDC Grids

This paper proposes a modular and scalable current flow controller (CFC) for meshed High Voltage Direct Current (HVDC) grids. The exchange of active power is performed directly between two DC branches and the circuit can be installed directly at a DC node without any additional AC grid. The CFC is especially suitable for medium CFC voltage ratings and neither an insulation to ground nor a transformer is needed. The basic design as well as the functional principle is presented and a control and balancing method is described, which allows a cell capacitor balancing and switching frequency control. Finally, full-scale simulation results validate the functionality of the proposed CFC.