Impedance-Based Harmonic Current Suppression Method for VSG Connected to Distorted Grid

摘要

For the virtual synchronous generator (VSG) connected to the distorted grid, it is difficult to address the distorted grid current issue by the conventional harmonic suppression methods. To address this issue, in this article, we propose an impedance-based harmonic current distortion suppression method without closed-loop control to improve the adaptability of VSG connected to the distorted grid, mainly consisting of the passive and active approaches. The passive branch separated from the decentralized filter inductor is installed between the point of comment connection (PCC) and grid to introduce an additional voltage variable, which will not add the system power consumption and cost. Meanwhile, through the proper feed-forward of the PCC voltage and the additional voltage variable, the active branch can increase the harmonic impedance viewed from the grid side to the VSG, and also reduce the output impedance viewed from the PCC to the VSG, which effectively solves the grid current distortion. Moreover, with a proper parameters design, the proposed method can adapt to a wide range of grid impedance variation. Finally, experiment results validate the proposed control method.