An Embedded DC Power Flow Controller Based on Full-Bridge Modular Multilevel Converter

Meshed dc grids help improve the current network's configuration, flexible power management, and reliable power supply. However, the existing power converters implemented in dc grids do not have enough controllability in adjusting each feeder's power, leading to transmission congestion, overloads, and high-power loss issues. The dc power flow controller (DCPFC) is prominent in addressing problems with a better system performance. This article proposes an embedded dc power flow controller (eDCPFC) with full-bridge modular multilevel converter (MMC) (FB-MMC) topology. The eDCPFC is directly integrated into a host MMC. The device's energy is balanced through the coordinated control of the eDCPFC and the host MMC without using isolation transformers or external power supplies. The working principle and the corresponding control strategies of the FB-MMC type eDCPFC and its host MMC are elaborated. Experimental results conducted in a scaled-down prototype validate the feasibility and effectiveness of the proposed topology and control schemes under typical working conditions.