Current Harmonic Suppression for Grid-Connected VSG Based on Virtual Harmonic Impedance

摘要

When the inverter controlled as a virtual synchronous generator (VSG)is connected to the non-ideal grid, the grid current will be severely distorted, especially when the line impedance is relatively small. However, the commonly used voltage-type VSG at present cannot directly control the output current of the VSG. Thus, this paper presented a method of harmonic suppression based on the virtual harmonic impedance (VHI). By introducing the VHI to the voltage-current dual loop, the equivalent virtual resistor and inductor of each harmonic can be configured independently according to the actual situation. Accordingly, the attenuation ratio of each harmonic current can be adjusted equivalently. The effectiveness of the VHI are verified by simulation.