Active alleviation of fatigue stress on blades by adaptively maneuvered deformable trailing edge flaps (DTEF)

The concept of "smart rotor" is an evolving advancement in wind turbine which enables an intelligent active flow control in rotor. The deformable trailing edge flap (DTEF) is a part of smart rotor concept which implements a customized active load control. The trailing edge flap actuator effectively replaces the tedious blade pitch actuation and conserves the actuation energy required for pitching the entire blade. The DTEFs require a fast computing, anticipatory controller for optimally tuning the flap angle with minimal power compromise. This work analyzes the performance of advanced control strategies like model predictive control (MPC), adaptive MRAC control, and DQ controllers. The MRAC controller is found to reduce the fatigue stress by 40% and the MPC controller damps up to 70% more efficiently than the typical feedback controller. The control strategies are aided by the LiDAR-based preview wind data for the active manipulation of trailing edge flap angle (theta(flap)) control. The validation of proposed controller is done using power analysis curve and the component fatigue lifetime analysis using MLIFE software. The above analyses are done in NREL Onshore 5-MW FAST wind turbine model which could be interfaced with MATLAB with modified AeroDyn code for active flap deflection.