Dynamics and Stability of Grid-Interfaced Converters: A Comparative Study of Grid- Following and Grid-Forming Technologies

Large-signal stability analysis of grid-interfaced converters is essential to understand their behavior under significant disturbances such as voltage sags during faults. The different synchronization control methods for converters complicate the large-signal stability analysis. Thus, the dynamic equations for different grid-forming (GFM) and grid-following (GFL) converters and the corresponding physical analogy are described. Then, a comparative large-signal stability analysis of converters is conducted based on geometric method, Lyapunov method and time-domain simulation, covering voltage-, power-, virtual oscillator-based synchronizations.