Optimal VSG BESS Sizing for Improving Grid-Following Converter Stability Under Various Dispatch Scenarios and Grid Strengths

As renewable energy integration increases, ensuring stability of Inverter-Based Resources (IBRs) in weak grids is crucial, as grid-following (GFL) converters often become unstable under such conditions. Integrating virtual synchronous generator (VSG) batteries has shown potential to improve GFL stability, but determining the optimal size of the VSG required for stability remains an open question. Existing research typically relies on small-signal or impedance models for stability analysis, which are only valid at a single operating point and do not consider the full range of operating conditions, including various dispatch scenarios and grid strengths. This paper addresses this gap by proposing a novel methodology to visualize the system's stable operating region, offering insights into stability boundaries across various real power and grid impedance variations. Additionally, it introduces an optimal VSG battery sizing strategy that accounts for these variations, ensuring stability while minimizing VSG capacity. The strategy's effectiveness is validated through comprehensive PSCAD simulations, demonstrating its reliability across a wide range of real power and grid impedance operating points.