US Patent 9422915 Customizing a wind turbine for site-specific conditions

After establishing a design environmental condition (26, S1) for a wind turbine blade, and engineering a coefficient of lift and a corresponding optimum blade tip speed ratio (TSR 21) that maximizes annual energy production of the wind turbine when operating under the design environmental condition, determining a site-specific condition (28, S2, S3) that changes a wind loading condition on the blade compared to the design environmental condition, and providing an add-on device (49, 50, 60) for the blade that maximizes annual energy production of the wind turbine under the site-specific condition by changing the coefficient of lift and optimum TSR of the blade. Site specific conditions may include reduced RPM (28) for noise curtailment and/or specific mean wind speeds (S2, S3). The add-on device may include a flap (49, 60) and/or vortex generators (50).