Triple Converter Cooperative Control Strategy for Doubly Fed Induction Generator

Introduction: With the increase of large-scale wind power grid integration requirements on power system stability, the problem of insufficient high and low voltage ride-through performance of Doubly-Fed Induction Generator (DFIG) is becoming more prominent. Improving the high- and low-voltage ride-through performance of the DFIG by enhancing its control strategy has become a key technology path to enhance the grid adaptability of wind power systems. Therefore, this article proposes two novel control strategies for the Parallel Grid-Side Converter (PGSC), designed to enhance the high- and low-voltage ride-through capabilities of the DFIG. Method: This article establishes a mathematical model of PGSC, introduces model predictive control and direct current control theory, and proposes two predictive control strategies: one is a predictive control scheme based on PGSC topology, and the other is a predictive model based on direct current control principle. Results: Through MATLAB/Simulink simulation analysis, the above two control schemes were compared with conventional PI control for high and low voltage ride-through, and an effective predictive control scheme was derived. Discussion: During three-phase voltage sags, the PGSC topology-based predictive control scheme reduces DC bus voltage fluctuation by 81.8% and 86.2% compared to direct current control-based and conventional PI methods, respectively, while improving transient acceleration performance by 58.4% and 60.9% over the same counterparts. Conclusion: The prediction scheme based on the PGSC topology structure can effectively track the reference value, suppress the phenomenon of DC bus overvoltage, and accelerate the transient process of the grid-side voltage and current.