Sizing and control of trailing edge flaps on a smart rotor for maximum power generation in low fatigue wind regimes

Abstract

In this paper an extension of the spectrum of applicability of rotors with active aerodynamic devices is presented. Besides the classical purpose of load alleviation, a secondary objective is established: power capture optimization. As a first step, wind speed regions that contribute little to fatigue damage have been identified. For these regions the turbine energy output can be increased by deflecting the trailing edge (TE) flap as a function of local, instantaneous speed ratios. For this purpose, sizing of TE flap configuration for maximum power generation is established using blade element momentum theory. The investigation then focuses on operation in non-uniform wind field conditions. Firstly, the deterministic fluctuation in local tip speed ratio due to wind shear was evaluated. The second effect is associated with delays in adapting the rotor speed to time varying inflow. The increase of power generation due to wind shear has been demonstrated with an increase of energy yield of 1%. Finally a control logic based on inflow wind speeds has been devised.