Active frequency support control strategy for grid-forming inverters

High-penetration wind power generation utilizes significant power electronics for grid integration. Unlike conventional synchronous generators, these systems lack inherent inertial response, making it challenging to maintain system frequency stability during external disturbances. Grid-forming wind turbines employing virtual synchronous control can provide frequency support without relying on phase-locked loops. To address the issue of significant frequency and power fluctuations in grid-forming wind turbines under virtual synchronous control during external disturbances, this paper proposes an active frequency support control strategy based on adaptive inertia and damping. Using a direct-drive PMSG-based system as a representative case, we first establish mathematical and small-signal models of the wind turbine system. Secondly, eigenvalue analysis (root locus) is employed to investigate the influence of key grid-side control parameters on system frequency response characteristics. Based on this analysis, a parameter-adaptive frequency support control strategy is developed. Finally, the accuracy of the small-signal model and the effectiveness of the proposed control strategy are validated through MATLAB/Simulink simulations. Results demonstrate that the designed control strategy effectively reduces both frequency deviations and power fluctuations under disturbance conditions.