The optimal configuration method of the capacity of the grid-forming converter for supporting the grid strength

This paper investigates the challenges of grid strength and stability arising from the large-scale integration of renewable energy, with a focus on the dynamic response characteristics of grid-following (GFL) and grid-forming (GFM) converters. Utilizing an electromagnetic transient model and equilibrium point linearization, voltage response equations at the point of interconnection under grid voltage disturbances are derived, highlighting the distinct behaviors of the two converter types during voltage sags. This paper analyzes the relationship between internal impedance and controller parameters, and proposes an extended equivalent model for multi-converter parallel integration scenarios. The short-circuit ratio (SCR) is adopted as a quantitative metric to assess grid strength, and an optimal converter configuration strategy is proposed to satisfy critical short-circuit ratio (CSCR) requirements. Finally, single-converter and multi-converter simulation models are constructed in Simulink to compare the voltage response characteristics of both converter types, and to validate the effectiveness of the proposed strategy in enhancing grid strength.