Improved linear active disturbance rejection control for mitigating subsynchronous control interaction in DFIG systems.

Series-compensated transmission networks can induce subsynchronous control interaction (SSCI) in doubly fed induction generator (DFIG) wind farms due to interactions between converter control dynamics and series capacitors. These interactions can amplify subsynchronous oscillations and threaten system stability. To mitigate this issue, this paper proposes an improved linear active disturbance rejection control (I-LADRC) strategy for the rotor-side converter inner current loop. The proposed I-LADRC reconstructs the error-feedback law of conventional LADRC (C-LADRC) by incorporating integral action while retaining active disturbance estimation and compensation, thereby providing partial structural separation between the tracking dynamics and observer-bandwidth tuning. Frequency-domain and small-signal stability analyses demonstrate that the proposed method provides improved SSCI damping and disturbance suppression compared with PI and C-LADRC. Based on these characteristics, a constrained Pareto-based parameter-design procedure is developed, in which full-system stability is enforced while SSCI-band disturbance attenuation is balanced against high-frequency measurement-noise transmission. Hardware-in-the-loop (HIL) experiments validate the theoretical findings and confirm the effectiveness and practical applicability of the proposed controller for SSCI mitigation in DFIG-based wind energy systems.