Predictive model of wind turbine rotor-blade deflection

Abstract

A simulation process has been developed to predict wind turbine rotor-blade deflection caused by gravity effects. The model is based on the rotor-blade segmentation in finite elements, each one considered as an independent structure. The simulation has been extended to n-elements to make a more precise approach to the real performance. The range of deformation has been determined for a wind turbine rotor-blade analysing the effects of forces that creates a bending moment and estimating the permanent deformation. Accelerated deformation tests have been run to evaluate the deflection and angular phase shift with time in ranges that can be compared to real situations. The accelerated deformation process has been achieved by a constant load equivalent to 22.5 times the rotor-blade weight. The results have been compared to those obtained from experimental tests in a prototype operating under similar conditions. The results of the comparison have demonstrated the validity of the theory, within 95% accuracy. The high accuracy of the results indicates the simulation process can be applied to bigger wind turbines within a minimum error. The predictive model estimates how the deflection at the blade tip of wind turbine rotors evolves with time; the prediction, for the lifespan of a wind turbine rotor-blade of 25 years, results in deflection from 0.115 m for small wind turbines of 14 m of diameter (50 kW) until 1.315 m for large wind turbines of 114 m of diameter (4.5 MW).