A new fault ride-through control strategy for virtual synchronous generator based on virtual impedance

New energy grid-connected inverters based on virtual synchronous generator (VSG) control can provide inertia for the grid, damping, and frequency and voltage regulation support to the grid, but face the risk of overcurrent during grid voltage dips. A new fault ride-through control strategy for VSG based on virtual impedance is proposed to address the above problems. First, the fourth-order model of synchronous generator is introduced on the basis of the conventional VSG control strategy, and a new VSG control strategy is constructed, which effectively improves the reactive power support capability; then, considering the uneven distribution of reactive power caused by the voltage drop at the parallel grid point after a line fault, a virtual impedance link is introduced into the conventional VSG control, which effectively limits the fault current magnitude. Finally, a simulation model is built in PSCAD/EMTDC to compare the reactive power support capability under different control strategies, which verifies the effectiveness and superiority of the proposed method.