Active stall control for large offshore horizontal axis wind turbines; a conceptual study considering different actuation methods

• Published in: Journal of physics. Conference series 2014-01, Vol.555 (1), p.12082-21
• Main Authors: Pereira, R, Bussel, G J W van, Timmer, W A
• Format: Article
• Language: English
• Subjects: Active control; Actuation; Actuators; Aerodynamic coefficients; Boundary layers; Coefficients; Dielectric barrier discharge; Feasibility studies; Horizontal Axis Wind Turbines; Lift; Offshore; Physics; Robust design; Stall; Transpiration; Turbines; Wind power
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/555/1/012082

The increasing size of Horizontal Axis Wind Turbines and the trend to install wind farms further offshore demand more robust design options. If the pitch system could be eliminated, the availability of Horizontal Axis Wind Turbines should increase. This research investigates the use of active stall control to regulate power production in replacement of the pitch system. A feasibility study is conducted using a blade element momentum code and taking the National Renewable Energy Laboratory 5 MW turbine as baseline case. Considering half of the blade span is equipped with actuators, the required change in the lift coefficient to regulate power was estimated in ΔCl 0.7. Three actuation technologies are investigated, namely Boundary Layer Transpiration, Trailing Edge Jets and Dielectric Barrier Discharge actuators. Results indicate the authority of the actuators considered is not sufficient to regulate power, since the change in the lift coefficient is not large enough. Active stall control of Horizontal Axis Wind Turbines appears feasible only if the rotor is re-designed from the start to incorporate active-stall devices.