Multiple-time-scales parameters stability domain construction for grid-connected direct-drive wind power generation system

The interaction between wind power generation systems and weak power grids can easily lead to system instability, characterized by multiple-time-scales dynamics. To investigate the stable operation mechanism and control parameters of the interaction system under multiple-time-scales, a simplified interaction model of direct-drive wind power generation systems and weak grids is developed. This model establishes a single-input single-output transfer function incorporating operating point variables. On this basis, the multi-time-scales stable operating characteristics of the interaction system, both in series and parallel configurations, are thoroughly analyzed. The stable operating range of control parameters for each time scale is innovatively constructed. By integrating frequency-domain stability indicators with the system's dynamic response performance, the stability domain is further refined. The study explores the variation range of stable operating parameters across the entire wind speed range and under different short-circuit ratios. Additionally, the dominant control loops responsible for stabilization are identified, and an effective parameter design process for each control loop is proposed. With the proposed parameter design, the system can maintain stable operation across the entire wind speed range, even with a short-circuit ratio as low as 2.9. Finally, simulation model of the system is implemented in MATLAB/Simulink, and a small-scale wind power experimental platform is established. Both simulation and experimental results validate the effectiveness of the proposed stable parameter domain construction strategy.