Sequence Impedance Model-Based Harmonic Current Suppression Method for VSG Connected to the Grid

When the virtual synchronous generator (VSG) control is connected to a weak grid with background harmonics, the voltage distortion of the grid will cause a large amount of harmonics in the output current of the VSG, and may lead to system oscillation. To enhance the stability of the grid-connected system, an optimization control strategy based on the sequential impedance model of virtual synchronous generator for grid connection was proposed. By improving the control strategy, the system is able to adapt to the changes in the grid state in real time. Compared with the traditional control method, the grid-forming system’s stability margin is greatly increased by the enhanced control technique, which also raises the phase in the low frequency range. The experimental findings demonstrate that the enhanced control approach can guarantee the system’s stable functioning and prevent unstable oscillations from occurring.