Control and Optimization of a Wind Energy Conversion System Based on Doubly-Fed Induction Generator Using Nonlinear Control Strategies

Classical vector control schemes use proportional-integral (PI) controllers for wind energy conversion system (WECS) based on doubly-fed induction generator (DFIG) present many drawbacks and limitations, such as sensibility to DFIG's parameter variations, parameter adjustment difficulties and less robust against the external and internal disturbances. Therefore, and to overcome these inconveniences, nonlinear control strategies of the DFIG-model will be more appropriate to ensure better results than that of the PI controllers. In this paper, three control techniques: fuzzy-sliding mode (FSMC), second-order sliding mode (SOSMC) and integral backstepping (IBSC) for both the rotor side converter (RSC) and the grid side converter (GSC), using a pulse width modulation (PWM) with fixed switching frequency, of the whole WECS are presented and designed. The principal purpose of proposed control strategies is to extract the maximum power (MPPT) and keeping a stable operation of a DFIG and its converters during internal and external uncertainties. The overall results are afforded by simulation in the SIMULINK/MATLAB software. Simulation results exposed in this work demonstrate the robustness of each control strategy in spite of the different disturbances and uncertainties.