Research on Power Voltage Characteristics of MMC-HVDC grid based on MMC Control

In this paper, DC power and voltage characteristics in MMC-HVDC grid are analyzed. Coupling between DC voltage and power in MMC grid under power imbalance is proposed based on MMC converter response, and time-varying curve of DC voltage is analyzed. A simplified model of four-terminal MMC-HVDC grid is built, and simulations of DC voltage change under power imbalance is done. Analyses and simulation results show that, under fixed control response; a positive proportional relationship exists between power variation and DC voltage variation. Time-varying curve of DC voltage can be calculated by a first order differential equation.