Doubly-Fed Induction Generator (DFIG)-based wind energy conversion systems are highly sensitive to grid voltage unbalances, which introduce negative-sequence components that can cause severe performance degradation, including stator and rotor current oscillations, electromagnetic torque ripples, increased thermal stress, and reduced system reliability. This paper presents a simple and effective compensation strategy for negative-sequence components in DFIG systems operating under unbalanced grid conditions.

A control architecture is developed to regulate the positive-sequence system and to compensate for the negative-sequence components, enabling effective suppression of oscillatory power components and mitigation of double-frequency torque pulsations. A dedicated compensation system is introduced to actively suppress the negative-sequence components by injecting counteracting signals through the rotor-side converter (RSC), thereby restoring balanced operating conditions and minimizing the impact of grid asymmetries on the generator performance. The effectiveness of the proposed method is further evaluated through a comparative analysis with state-of-the-art approaches reported in the literature.

The performance of the proposed control strategy is evaluated through detailed simulations under various unbalanced voltage scenarios. Furthermore, hardware-in-the-loop (HIL) simulations are conducted, also considering aspects specified in IEC TS 61400-21-4. Results demonstrate significant reduction of negative-sequence effects while maintaining optimal positive-sequence active and reactive power control.