Capacity Planning for Virtual Synchronous Generator Batteries to Enhance Small-Signal Stability of Grid-Following Converters

The transition to renewable energy sources has presented significant challenges to power system stability, particularly with the increased deployment of inverterbased resources (IBRs). Grid-following (GFL) converters are effective in maintaining stability under strong grid conditions but become unstable in weaker grids. Conversely, grid-forming (GFM) controls, such as virtual synchronous generators (VSGs), enhance stability through voltage support and frequency regulation but may become unstable under high system strength. This paper investigates the combined application of GFL and GFM control strategies to improve overall system stability. A small-signal model is developed for a multi-converter system integrating both GFL and VSG converters connected to an infinite bus. The study examines the impact of varying VSG/GFL capacity ratios on system stability. The proposed methodology demonstrates effective stabilization across different grid conditions, with PSCAD simulations validating that incorporating 20% VSG converters into GFL systems enhances stability under diverse grid strengths. This research provides an analytical framework for assessing stability in multi-converter systems and offers practical guidelines for integrating VSG batteries with existing IBR infrastructure.