A three-port power flow controller for HVDC grids

This work proposes a three-port converter structure for high-voltage dc (HVDC) applications to facilitate power flow routing between a controlled dc bus and two independent dc networks. Control of line power flows is achieved via the series injection of incremental dc voltages between the networks, thus the converter structure is only rated for a fraction of the rated power and voltage of the connecting dc networks. Unlike previously proposed dc power flow devices, a significant advantage of the presented structure is that the incremental dc voltages are generated without requiring power exchange with an external ac network. As a result, the proposed converter structure offers a highly cost-effective means of routing and controlling dc power flows within emerging HVDC grids.