Noncontrolled fault current limiter with reactive power support for transient stability improvement of DFIG-based variable speed wind generator during grid faults

According to the recent grid codes, wind turbine systems (WTSs) are required to stay connected to the grid during grid faults and provide reactive power to support the grid. Therefore, this paper proposes a noncontrolled fault current limiter (NCFCL) with reactive power support for transient stability improvement of DFIG-based WTSs under grid faults. The proposed NCFCL is based on a nonsuperconducting reactor located in the rotor side. The NCFCL considerably limits the rotor and stator overcurrents and improves the transient stability of the doubly fed induction generator (DIFG). In addition, the proposed strategy reduces DC-link overvoltage and electromagnetic torque oscillations and also provides reactive power to the grid to support the grid voltage recovery. In this way, the fault ride-through (FRT) requirements of the latest grid codes can be fulfilled without affecting the DFIG stability in normal operation. Simulation studies using MATLAB/Simulink-2019a are performed on a 2-MW DFIG-based WTS to confirm the effectiveness and feasibility of the proposed FRT strategy. Simulation results reveal that the proposed strategy provides better performance compared to the crowbar protection to improve the FRT capability. © 2021 John Wiley & Sons Ltd.