Aerodynamic physics of smart load control for wind turbine due to extreme wind shear

• Smart rotor control due to the extreme load and its flow physics were proposed.
• The extreme wind shear load on blades was effectively reduced.
• The control positively affected the loads on the drive-chain components.
• The essence of the synchronized flow-blade interaction was modified.

This paper presents a numerical investigation of the smart load control on an Upwind/NREL 5 MW reference wind turbine under the IEC extreme wind shear (EWS) condition utilizing newly developed aero-servo-elastic platform. The control action was implemented through the local perturbation of a deformable trailing edge flap (DTEF) per blade, which was driven by a smart rotor system, based on the FAST/Aerodyn and Matlab/Simulink codes. Results showed that, compared with the original collective pitch control method, the aerodynamic load in terms of blade flapwise root moment and tip deflection were effectively reduced. Furthermore, the smart rotor control also positively affected other components of the drive-chain as well as generator power and pitch system. It was found that the smart control effect altered the nature of the flow-blade interactions and changed the in-phased fluid-structure synchronization into much weaker couplings. As a result, the damping of the fluid-blade system was significantly enhanced, leading to great attenuation in the EWS load on both rotor and other drive-chain components.