Development and experimental verification of a 5 kW small wind turbine aeroelastic model

Aeroelastic modelling is regularly used in the design and analysis of commercial scale wind turbines, but has seen comparatively little use in the development of small wind turbines. Fewer studies still have considered experimental validation of model performance with field measurements. This study details the development of an aeroelastic model of a 5 kW horizontal-axis Aerogenesis turbine within FAST. The model includes rotor aerodynamics, blade and tower structural freedom, free-yaw tail fin dynamics, and a self-excited induction generator incorporating maximum power point tracking variable speed control. This model was compared to measured operating data to assess aerodynamic and structural performance. Blade loadings and deflections were simulated within 8% and 10% respectively at design conditions in the azimuthal domain. Simulated rotor speed control and tail fin motions were bounded by measured field data. The simulated control system model was found to act aggressively, with a mean over-prediction in tip speed ratio of 11%. Areas for future model improvement are discussed in this paper. The resulting aeroelastic model and methodologies presented here are expected to further the use of aeroelastic modelling in the small wind turbine field. Particular applications may include the verification of performance and design loads specified in IEC 61400.2.