A Multiport Power Flow Controller for Meshed High Voltage DC Grids

In multiterminal or meshed high voltage direct current (HVDC) grids, the power flow of each line cannot be accurately controlled by the voltage source converter (VSC) controllers. It may lead to unnecessary power losses and even damage the entire power transmission system. To solve this problem, the dc power flow controller (DCPFC) is introduced. This article proposes a novel multiport DCPFC topology which consists of three parts: series tapping block, energy transfer block and parallel tapping block. The proposed DCPFC topology can regulate one or more line currents in the dc grid. The line currents can be regulated independently. It is suitable for medium voltage (MV) or high voltage (HV) de systems due to its modular structure. Since the DCPFC only contains one stack, the costs and power losses can be reduced. Meanwhile, this article also elaborates on the topology structure, operation principle, and control strategy of the proposed topology. The theoretical analysis is verified by simulation results conducted in MATLAB/Simulink.