DC line power flow coordinated control of MMC-MTDC with virtual synchronous generator

• A virtual synchronous generator (VSG) control strategy with DC line power flow regulation. • Integrates the inertia-support capability of VSG control for the AC grid with the stabilizing function of DC line power flow control. • A small-signal model of a four-terminal MTDC system considering DC grid coupling. The coordinated regulation and control of DC line power flow is a critical factor in ensuring the stable and safe operation of the multi-terminal DC (MTDC) system. In this paper, a virtual synchronous generator (VSG) with a DC power flow controller (DPFC) is proposed for MTDC. A DC line power flow coordinated control of MMC-MTDC is achieved by adjusting the DC voltages integrated with active power regulation of VSG. The basic and the modified VSG control are appropriately assigned to the MMC stations of the MTDC system. Moreover, the impacts of control parameters on system performance are analyzed based on the small-signal model, and corresponding guidelines for parameter design are provided. The performance of the proposed control method is validated through a four-terminal MMC-MTDC simulation under various conditions, including power flow step and reversal tests. The effectiveness and robustness of the control are further demonstrated in the CIGRE benchmark model with 11 terminals under multiple complex scenarios. The simulation results demonstrate the effectiveness of DC line power flow control as well as the stability and sufficient inertia of the system.