Power Oscillation Suppression in Multi-VSG Grid by Adaptive Virtual Impedance Control

When multiple virtual synchronous generators (VSGs) operate in parallel, severe power oscillation may be suffered. To deal with this issue, this article offers an adaptive virtual impedance method applied to a multi-VSG grid. The core idea is to change the output active power by adaptive virtual impedance. When the angular frequency of the local controller is greater than the angular frequency of the neighbors’ controllers, the output active power of local VSG falls, and thus dω_i/dt rises. Then, as the angular frequency is lower than neighbors’, the output active power rises, and dω_i/dt falls. As a result of this, the method facilitates the consistency of response curves of all angular frequencies. Besides, the stability of the offered algorithm is demonstrated. A final proof of the efficacy of the proposed control method is shown by simulation and hardware-in-loop results.