Stability analysis of frequency small signal of grid-connected VSG based on passivity-based control

Abstract

To achieve better frequency stability, the voltage and current inner loop control strategy based on Euler-Lagrange passivity-based control (EL-PBC) is used to replace the traditional PI control of microgrids under complex power grid conditions. To analyze the frequency stability of the grid-connected Virtual Synchronous Generators (VSG) system under disturbance conditions, a general small-signal model for a VSG system under EL-PBC is established. All characteristic roots of the system are obtained, and participation factors are calculated to identify the dominant state variables corresponding to these characteristic roots. A comparative analysis of the characteristic roots of the EL-PBC system versus traditional control systems is conducted. It shows that the frequency stability is better under passivity-based control under disturbance, and the influence of passivity-based control parameters on the characteristic roots is analyzed. Finally, the correctness of the theoretical analysis is verified by simulation.