Closed-Loop Control Wind Tunnel Tests on an Adaptive Wind Turbine Blade for Load Reduction

Wind tunnel tests on a non-rotating, dynamically scaled wind turbine blade equipped with variable trailing edge geometry were carried out. The effectiveness of the system for active load reduction purposes, with the interaction between structural dynamics, aerodynamics and control was tested. The actuation of the adaptive trailing edge was based on a piezoelectric bender actuator. The full aeroservoelastic system was identified based on input and output measurement signals. A feedback controller, using strain signals on the blade root, was designed, tuned and applied on the system in order to minimize root bending moments. The results show remarkable performance in reduction of blade root strains for both open-loop and closed-loop tests. The sensitivity of various design and control parameters are analyzed both in the prescribed cases and in the feedback-controlled system.