Fault Ride-Through Capability Enhancement of DFIG-Based Wind Power Plants Using BESS-STATCOM

The stochastic nature of wind speed and low inertia of Wind Energy Conversion Systems (WECSs) contribute to grid voltage instability, inadequate reactive power support, and increased susceptibility to grid faults. Particularly, Doubly Fed Induction Generator (DFIG)-based WECS is more perceptive to disturbances due to direct connection of its stator to grid and partially rated back-to-back converter (typically 25-30% of the generator rating). Therefore, the increasing penetration of WECSs in modern power grids necessitates robust Fault Ride-Through (FRT) capabilities to ensure stable operation during grid abnormalities. Static Synchronous Compensators (STATCOMs) offer superior FRT support through fast dynamic response and effective reactive power compensation; however, their performance degrades during deep or prolonged voltage dips due to dc-link voltage fluctuations and their inability to provide active power. To overcome these constraints, this paper proposes a coordinated control strategy for an integrated Battery Energy Storage System (BESS) and STATCOM, called BESS-STATCOM, aimed at improving the FRT capability of DFIG-based WECSs. The proposed control approach dynamically allocates reactive and active power support through coordinated operation where the STATCOM ensures rapid reactive current injection and the BESS stabilizes the dc-link voltage and provides sustained active power during extended faults. In addition, a decoupled positive and negative-sequence control scheme is developed to mitigate voltage unbalance and limit stator and rotor overcurrent during asymmetrical faults. Comprehensive simulations under diverse grid faults demonstrate that the proposed BESS–STATCOM strategy enhances system resilience, improves voltage stability, reduces generator overcurrent, and ensures grid code compliance.