Wind turbine efficiency optimization. Comparative study of controllers based on second order sliding modes

This paper studies the applicability of second order sliding mode control strategies to a wind energy conversion system aiming to optimise its power conversion efficiency. Four different controllers are designed and analysed, based on the “sub-optimal”, “twisting”, “super-twisting” and “with a prescribed law of variation” algorithms, which present finite-time convergence, robustness, chattering and mechanical stress reduction, and are of quite simple online operation and implementation. Representative simulation results are shown, using a complete model of the system under realistic operating conditions, where the performance of the controlled system can be appreciated for each of the controllers and some comparisons can be made.