An Output Current Harmonic Suppression Method of VSG by Designing Harmonic Current Control Loop With I‐SOGI Under Distorted Grid

ABSTRACT The output current becomes severely distorted when virtual synchronous generator (VSG) is connected to distorted grid. Traditional current harmonic suppression methods are highly sensitive to grid impedance and carry the risk of system destabilization due to overmodulation. To solve these issues, an output current harmonic suppression method of VSG by designing a harmonic current control loop with integrated second order generalized integrator (I‐SOGI) is proposed in this paper. Specifically, a harmonic current control loop is designed and integrated into the voltage and current dual closed loop to directly suppress the output current harmonic. Meanwhile, an I‐SOGI with the harmonic gain factor is designed to accurately track the harmonic references. This significantly enhance the harmonic output impedance of VSG, which substantially improves the quality of the output current. Compared with existing methods, the proposed method not only drastically reduces the sensitivity to the grid impedance but also considerably reduces the risk of system instability caused by overmodulation. Finally, the comparative experiments in the hardware‐in‐the‐loop (HIL) experimental platform verify the effectiveness and advantages of the proposed method.