Dynamic Inertia Modeling and Evaluation of MMC-HVDC with Virtual Inertia Control

The application of MMC-HVDC decouples the frequencies between AC systems, which further deteriorates the inertia of the system. Virtual inertia control has been proposed to alleviate this problem. However, because of the complex coupling among controllers and DC voltage dynamics, the inertial characteristics of the MMC applying this strategy are not clear yet. In this paper, the magnitude-phase motion model of the MMC with virtual inertia control is first established. By analogy with the swing equation of a synchronous generator, the equivalent dynamic inertia of MMC is derived. On this basis, the impacts of each controller and circuit components on the inertia are analyzed. Finally, the analytical results are verified by MATLAB/Simulink simulation.