Full-State Feedback Power Decoupling Control for Grid Forming Converter With Improved Stability and Inertia Response

Virtual synchronous generator (VSG) control strategies have been widely researched and applied in grid-forming converters for utility grid inertia support under high level penetrations of renewable energies. Traditional VSG control encounters coupling issues between active and reactive power loops, especially in low voltage resistive feeder line conditions. This power coupling effect degrades not only the effectiveness of inertia support during transients, but also the system stability. In this article, the coupling mechanism between active and reactive power loops is analyzed and a full-state feedback control method is proposed to release the coupling issue in traditional VSG control. In the proposed control, the state feedback matrix is designed to eliminate the power coupling between active and reactive power control loops, and fully retain the capability for active and reactive inertia response. Disturbance injection is applied to avoid dependence on line parameters. Root locus analysis shows that the decoupled power control endows system with better stability and damping performance. Hardware experimental results indicate that the power decoupling VSG significantly releases the coupling between active and reactive power, contributing to better system stability and providing improved transient power inertia response to power grid.