In this chapter, a comparative analysis is made for doubly-fed induction-generator (DFIG) low-voltage ride-through (LVRT) solutions. It is supposed to improve the LVRT capability of DFIG under unbalanced grid voltage conditions by hardware or software solutions. Therefore, this chapter proposes a low-cost software LVRT solution based on an efficient control scheme of DFIG driven by a wind turbine. The proposed control scheme is based on dual-sequence decomposition technique and Lyapunov-based robust control (RC) theory. Under an unbalanced grid voltage conditions, the proposed control strategy not only eliminates effectively the oscillations of the active and reactive powers exchanged between the generator and the grid but also achieves the symmetrical and sinusoidal grid currents injection. Simulation analysis under MATLAB®/Simulink® has been carried out on a 1.5 MW DFIG-based wind-turbine-systems, and the results are presented and discussed to demonstrate the feasibility and the efficiency of the control strategy for a grid-connected application under unbalanced voltage supply. The proposed dual control scheme is shown to be able to successfully mitigate torque, stator power and currents pulsations as compared with the conventional vector control based on the single control scheme.
Part of the book: Stability Control and Reliable Performance of Wind Turbines