Impact of grid strength on grid-forming inverter performance: a comparative study of droop and virtual synchronous generator controls

Abstract This study investigates the performance of grid-forming inverters under both strong and weak grid conditions, focusing on two widely used control strategies: droop control and Virtual Synchronous Generator (VSG) control. The increasing integration of renewable energy sources has necessitated the development of advanced inverter control techniques that can ensure stable operation in grids with varying strengths. To address this challenge, the research aims to compare the dynamic responses of droop and VSG-controlled inverters, particularly under disturbances such as frequency deviations, phase jumps, and voltage sags. The methodology involves detailed simulation of power system models representing both robust and weak grids, with parameters adjusted to reflect realistic operating conditions. The simulation results indicate that while droop control exhibits faster convergence under certain disturbances in strong grids, VSG control consistently provides smoother transitions and improved stability, especially under weak grid conditions, due to its inherent virtual inertia and damping characteristics. These findings show the potential of VSG-based control in enhancing grid resilience and stability in modern power systems with high renewable penetration.