An Advanced Control Law Combining Sliding Mode and Fractional Calculus for Wind Energy Conversion Systems

This paper presents an improved nonlinear control law that combines the sliding mode control and the fractional-order control. The utility of the sliding mode control returns to its power in terms of stability against parameter variation, robustness against modeling uncertainties, and ease of implementation. The utility of the fractional order returns to its better model of the dynamic behavior of a studied system to enhance the performance of various controllers. The main purpose of this advanced law applied to the mechanical part based on the two-mass model of the three-blade horizontal axis variable speed wind turbine is to minimize the effect of the chatter phenomenon (which is the major disadvantage of the controllers due to its high-frequency oscillations that damage the considered system) and reduce the value of the peak of the electromagnetic torque. The novel law conserves the same benefits of the other controllers such as accurate tracking and robust stability, as proved by Lyapunov's theory. The effectiveness of the developed control law is compared with other controllers and is shown by simulation results and numerical results using MATLAB.