Compliant Blades for Passive Power Control of Wind Turbines

Abstract

Recent advances in analysis capabilities for wind turbine blade aerodynamics and structural dynamics enables a thorough understanding of the connection between the aerodynamic excitation and structural response of blades. By designing the blades using fibre reinforced composite materials, coupling between bending and torsion, for example, can be built-in. In the present work the objective was to investigate the capability of a 50 kW constant speed wind turbine to automatically shed power in gusts by feathering the blades, i.e. twisting them towards the relative wind vector thus reducing the angle of attack, whilst bending away from the wind. This numerical study demonstrated that it is difficult to achieve constant power output with compliant blades for a fixed speed wind turbine because a large amount of twist is required. This paper details the investigation and results obtained in this aeroelastic study of compliant blades made from fibre reinforced composite materials.