An Adaptive-Feedforward Power Decoupling for Grid-Forming Converters with Pre-Synchronization via Sliding-Mode Control

The grid-forming (GFM) converter is an effective solution for grid support. However, mode switching failures and power coupling challenges in weak grids pose significant safety risks. To address these challenges, an adaptive feedforward power decoupling method with pre-synchronization is proposed to achieve seamless switching and accurate power regulation without line impedance information. First, based on a small-signal model of the GFM converter, a power coupling coefficient considering the power control loop is presented to analyze the coupling mechanism. Second, a reactive power adaptive compensation channel is constructed, in which a sliding mode (SM) compensation controller is designed in the reactive power loop, to dynamically correct the voltage reference and achieve power decoupling. The proposed method achieves wide-range dynamic decoupling control without line impedance parameters, exhibiting strong grid adaptability. Third, an improved pre-synchronization strategy based on the SM controller is developed, which leads the virtual power to converge to zero, to ensure seamless switching between islanded and grid-connected modes. Finally, the effectiveness of the proposed method is validated through simulation and experimental results.