Nonlinear Backstepping Control Strategy for Direct-Drive Wind Turbine Based on PMSG

Wind energy is a renewable form of energy that uses the power of the wind to produce electricity. It is considered among the world’s fastest-growing energy sources. It is clean and environmentally friendly, producing no gas emissions that increase the global warming effect. Hence, it is essential to develop wind energy conversion system technologies and control strategies to achieve optimum performance, increase efficiency, and reduce environmental impact. This chapter presents a nonlinear control approach for a variable-speed wind turbine directly driven by a permanent magnet synchronous generator. In the first place, a method for tracking the maximum power point based on optimal torque control is presented. Additionally, a robust nonlinear controller is designed using a backstepping control strategy based on Lyapunov stability theory. Through this technique, system stability is ensured while maximizing wind power extraction. The main idea behind the backstepping control involves analyzing and decomposing a highly complex nonlinear system into a series of simple controllable subsystems. Furthermore, the whole system was implemented using MATLAB ® /Simulink ® software to prove the validity of this control strategy. Thus, simulation results show that despite high mathematical complexity constraints, backstepping control offers high efficiency and robustness, even in varying wind conditions.