Wind inflow observation from load harmonics: initial steps towards a field validation

Abstract. A previously published wind sensing method is applied to an experimental dataset obtained on a 3.5 MW turbine and a nearby hub-tall met-mast. The method uses blade load harmonics to estimate rotor-equivalent shears and wind directions at the rotor disk. A second independent method is used to extend the met-mast-measured shear above hub height to cover the entire rotor disk. Although the experimental setup falls short of providing a real validation of the method, it still allows for a realistic practical demonstration of some of its main features. The method appears to be robust to turbulent fluctuations and air density changes. Results indicate a good quality of the estimated shear, both in terms of 10-min averages and of resolved time histories, and a reasonable accuracy in the estimation of the yaw misalignment.