Subsynchronous Resonance in DFIG‐Based Wind Farms: Mechanisms, Mitigation, and Future Directions—A Review

The increasing penetration of doubly fed induction generator (DFIG)–based wind farms, combined with series‐compensated transmission and weak grid conditions, has significantly heightened the risk of subsynchronous resonance (SSR). In modern power systems, SSR is manifested as subsynchronous control interaction (SSCI), due to adverse interactions between converter control loops and grid impedance characteristics. This paper presents a review of SSR in DFIG‐based wind farms, synthesizing recent advances in mechanism identification, mitigation strategies, and detection techniques. Grid strength on SSCI susceptibility is critically examined. Mitigation approaches are comparatively analyzed across system‐level, device‐based, and control‐based categories. Field case studies and experimental validations are reviewed to highlight real‐world performance and limitations. In verified case studies, mitigation techniques such as resonant controllers, sliding mode control (SMC), and hybrid systems that combine static synchronous compensators (STATCOMs) with battery energy storage systems (BESSs) show effectiveness. Their broad implementation is hindered by enduring issues, including multimodal resonance in hybrid grids, the scalability of lab‐tested solutions, cybersecurity vulnerabilities, and a lack of data for AI models. The review also integrates recent advances in robust control frameworks for inverter‐fed systems, optimal energy storage sizing under wake effects, and coordinated multilayer mitigation architectures, addressing identified gaps in practical deployment. Finally, emerging trends and challenges related to adaptive control and coordinated mitigation are discussed. The review provides actionable insights for system planners and operators seeking robust SSR mitigation in renewable‐rich power systems.