基于序阻抗的虚拟同步机同步频率谐振现象

As for the synchronous frequency resonance (SFR) phenomenon existing in virtual synchronous generator (VSG), considering the shortcomings of multi-input multi-output power coupling SFR analysis models, a sequence-admittance and sequence-impedance based SFR analysis method is proposed by modeling the single-input single-output sequence impedance model that can describe the wide-frequency dynamics of the VSG, and the SFR phenomena of single-loop and multi-loop VSG are comparatively studied. Based on the pole distribution map of sequence admittance, the relationships between SFR and the VSG power control loop parameters, virtual impedance, inner-loop control and grid impedance are effectively studied. Based on the Bode diagrams of sequence-impedance, the damping characteristics of SFR with and without the inner-loop control are compared, and then the resonance mechanism of SFR in single-loop and multi-loop VSG is revealed from the perspective of negative damping. By building the experimental platform based on the RT-Box, the SFR phenomena of VSG under different control schemes and grid impedances are verified, indicating the optimal design direction of VSG control.