Impact of Virtual Synchronous Generators on Inter-Area Low Frequency Oscillation

With the rapid development of Virtual Synchronous Generators (VSG) technology, the influence mechanism of VSG on the low frequency oscillation characteristics of power system has become an issue that needs urgent research. In this paper, small-signal models of synchronous generators (SG) and VSG were established. Eigenvalue analysis were conducted to identify how frequency regulation ability and inertia of SG and VSG effect on low frequency oscillation. The comparison between both SG and VSG are implemented to clarify why their low frequency oscillation characteristics are different. Finally, the results revealed that the virtual impedance control of VSG is the key reason to make the oscillation characteristic of VSG different from SG. If the virtual impedance is small enough, the influence of VSG on low frequency oscillation will be similar to SG.