Adaptive Control of Non-affine and Uncertain Variable-Speed Variable-Pitch Wind Turbines Subject to Input Saturation through Nussbaum-Type Functions for Multi-input Systems with Unknown Directions

Using Nussbaum-type Functions for Multi-Input Systems with Unknown Directions, adaptive controllers are proposed and developed for a class of wind turbines with uncertainties, unknown disturbance, and subjected to input saturation. RBF neural networks are used to approximate the bounds of uncertainties and unknown disturbances sources, while Nussbaum-type Functions are employed to address the unknown input directions. Moreover, to improve the design's practicality, generic n-order dynamics are considered where there are $n$ non-affine control inputs as opposed to widely used dynamics considering 1 non-affine input. Further, auxiliary saturation surfaces are adopted to guarantee the closed-loop system's stability in the presence of input saturation. In the end, the closed-loop system's stability is proven analytically, and simulations are rendered to visualize the analytical proof.