Tradeoffs in Active Control of Aerodynamic Power and Loads on a HAWT Rotor

This paper explores the trade that exists between energy capture and fatigue life resulting from the use of blade pitch to regulate flatwise bending moments. It is indicated that fatigue life improvements up to the order of lOi are feasible at a fixed blade weight, or reductions of a factor of 5 in blade weight may be possible for a fixed fatigue life. The loss of energy capture associated with these gains is indicated to be on the order of 4.8% at fixed rated power. The configuration considered is a variable-speed, 2-bladed upwind configuration with a nominal rating of 600kW. Rotor speed is assumed to be controlled with generator torque (an ideal control law is assumed). Results from both linear analyses and nonlinear simulations are presented and compared for a teetered rotor with rigid blades operating in a 16mph sea level Rayleigh wind with uniform 17% turblence intensity.