A DC power flow controller and its control strategy in the DC grid

The operation principle of the dc power flow controller in the dc grid is presented, the impacts of the dc voltage and line equivalent resistance on dc power flow are analyzed. Based on these studies, a new dc power flow controller based on dual active bridge (DAB) topology is proposed accordingly in this paper. Compared with existing literatures, the proposed dc power flow controller is able to control the bi-directional power flow of the dc transmission line without requiring any external power supplies. PSCAD/EMTDC software simulations are carried out on a two-terminal double-line voltage source converter (VSC) based dc grid including with the proposed dc power flow controller. Furthermore, the corresponding experimental verification is undertaken using a scale-down prototype of the proposed dc power flow controller. The simulation and experimental results under various operation conditions show that the proposed dc power flow controller can effectively control the dc power flow as defined.