Active structural control for load mitigation of wind turbines via adaptive sliding-mode approach

Abstract

This paper studies the load mitigation problem for wind turbines by using active tuned mass dampers. A state space model for the tower/nacelle system is established with the consideration of tower/blade interaction. The uncertainties that appear in the damping matrix and natural frequencies are also considered in the controller design. External loads acting on the tower including the drag force induced by winds and the absolute base shear induced by the rotating blades are involved, and shaping filters for online generating these loads are proposed which can be easily implemented in numerical simulations. An adaptive sliding-mode controller is proposed to handle the system uncertainties, external disturbances and hard constraint, and also to improve the overall performance of the wind turbine system. Numerical simulations are performed to demonstrate the effectiveness of the proposed control law.