Coordinated Control of GFL and GFM Hybrid Systems for Transient Synchronization Stability Enhancement

Against the backdrop of increasingly power-electronics-dominated power systems, renewable energy resources are interfaced with the grid through power converters, which are generally categorized as grid-following (GFL) and grid-forming (GFM) converters according to their control principles. The parallel integration of GFL and GFM converters provides a promising solution for balancing system stability, economic performance, and grid-support capability. This paper investigates the transient synchronization instability of hybrid GFL–GFM systems subjected to grid faults. First, the dominant factors affecting the transient synchronization stability of individual GFL and GFM converters are identified, and corresponding stability-enhancement control strategies are developed. Then, considering the dynamic interactions between GFL and GFM converters in the hybrid system, a coordinated control strategy is proposed to enhance the overall transient synchronization stability of the hybrid system. Finally, the effectiveness of the proposed strategy is validated through simulations.