AUTOMATED MODAL TRACKING IN A 2 MW ONSHORE WIND TURBINE

This paper presents the strategy adopted to automatically track the variation of the modal parameters of an onshore wind turbine equipped with a dynamic monitoring system in operation for more than one year. The processing is based on state-of-the art parametric operational modal analysis algorithms, such as SSI-COV, SSI-DATA and p-LSCF, that are combined with a cluster analysis that permits an automated interpretation of stabilization diagrams. The continuous tracking of natural frequencies and modal damping ratios of the wind turbine main vibration modes under distinct operating conditions permitted an accurate characterization of the influence of the wind velocity, yaw angle and rotor rotation speed on the dynamic behavior of the instrumented structure.