Variable inertia virtual synchronous control strategy for cascaded H-bridge grid-connected inverter

A virtual synchronous control strategy based on variable inertia for the cascade H-Bridge grid-connected inverter control system is proposed in this paper, which is involved in the grid frequency regulation. Compared with the constant virtual inertia, the variable inertia can slow down the frequency sag or speed up the frequency recovery process when the frequency of the grid changes, thus increasing the damping of the system. In this paper, the variable inertia mechanism is introduced, and the control strategy of virtual synchronous machine grid-connection based on variable inertia is analyzed in detail. Finally, the MATLAB simulation model of the 3-phase 12-module cascade H-bridge virtual synchronous machine is built to verify the correctness of the proposed control strategy.