An oscillation damping method for frequency-detector-less virtual synchronous generators

Abstract

This paper presents an active power oscillation damping method for frequency-detector-less virtual synchronous generator (VSG) to enhance its transient stability and to avoid the ill effect of frequency detector. In the paper, first, the mechanism and the low-frequency oscillation model of a conventional VSG is derived and reduced to a second-order model. Then, a new way to obtain the damping power without using frequency detector is proposed in order to simplify the conventional one, which includes frequency detector. The new approach presents an equivalent third-order model, and based on small-signal state-space analysis, the dominant poles are assigned to the same place as the original one, so that we can fairly compare their dynamic performances. Finally, experimental results are performed to compare the proposed approach with some other VSG control methods. The experimental results show that the proposed approach does better in transient stability and power-sharing ability than other conventional VSG control methods.