Small disturbance oscillation suppression strategy for doubly-fed wind turbine based on joint control of LADRC and AQPR

To address the issue that small-signal oscillations on the rotor side of doubly fed wind turbines may propagate through multiple transmission paths and induce subsynchronous oscillations, this paper proposes a small-signal oscillation suppression strategy based on the combined control of linear active disturbance rejection control (LADRC) and adaptive quasi-proportional resonant (AQPR) control. LADRC is employed to replace the conventional PI controller in the inner current loop of the rotor-side converter, where real-time disturbance estimation and compensation effectively block the propagation of small-signal oscillations within the current loop. Meanwhile, by integrating the intrinsic time-scale decomposition (ITD)-based oscillation frequency identification algorithm with a frequency-locking update module, an AQPR suppressor is constructed to achieve frequency-selective suppression of time-varying small-signal oscillations embedded in cross-coupled current signals. Based on this framework, an LADRC–AQPR combined current-loop control system is established, and key parameters are optimally designed to mitigate subsynchronous control interactions. Simulation and experimental results further provide systematic comparisons between LADRC-, QPR-, and ITD-based methods and their conventional counterparts in terms of oscillation identification and suppression performance, demonstrating that the proposed method exhibits superior dynamic response and enhanced robustness. Moreover, comparative validations under three typical operating conditions confirm that the proposed combined control strategy significantly outperforms conventional approaches in suppressing small-signal oscillations and can effectively mitigate time-varying small-signal oscillations in grid-connected doubly fed wind turbine systems.