Analysis and Improvement of Synchronous Frequency Resonance Caused by Imbalance DC Components

Abstract

Virtual synchronous generator (VSG) control strategy of distributed power generation system (DPGS) is an attractive interfacing solution for high-penetration renewable generation systems. However, in the case of short micro network feeder conditions, DPGS exhibits synchronous frequency resonance (SFR) phenomenon in the face of imbalanced DC components in power gird. This paper uses small signal analysis method to deduce the SFR mechanism in detail, which has not been well-explored in the prior research. Then discusses the effect of line impedance on its dynamic stability and proposes to add the use of virtual resistance in the control link to reduce the resonance peak, so as to solve the SFR problem. Finally, simulation and experiment results verify the correctness of the mechanism and the effectiveness of the suppression method.