Research on long-horizon model predictive control and seamless switching of grid-forming converters in hybrid systems

With the increasing penetration of renewable energy, the inertia and voltage support capability of power systems have significantly declined, making the secure and stable operation of hybrid systems composed of grid-forming (GFM) and grid-following (GFL) converters a research hotspot. To address the limited dynamic response and insufficient harmonic suppression capability of the conventional current PI inner loop in virtual synchronous generator (VSG), this paper proposes a VSG control strategy based on long-horizon model predictive control (MPC). While preserving the outer-loop structure of VSGs, the proposed method improves current tracking accuracy and dynamic performance through a two-step prediction mechanism, thereby effectively enhancing frequency stability and reducing grid-injected current total harmonic distortion (THD). Furthermore, to mitigate the voltage and current transients induced by GFM/GFL mode transitions in hybrid systems, a seamless switching control method is developed, enabling smooth operation under both strong and weak grid conditions. Simulation results demonstrate that the proposed strategy significantly enhances system dynamic performance and power quality, while improving the operational flexibility and stability of renewable-dominated power systems.