Modal Identification of a Wind Turbine Via a Hybrid Operational Modal Analysis Scheme Considering Harmonic Interference

Operational Modal Analysis (OMA) is an essential tool for determining structural dynamic properties of wind turbines. However, the presence of harmonic excitation in wind turbines poses a significant challenge for the effective application of traditional white noise-based OMA techniques. When some harmonic frequencies are close to structural frequencies, harmonics may introduce bias in modal estimations or be misidentified as structural modes, thereby resulting in inaccurate determination of structural dynamic properties of wind turbines. To this end, a hybrid OMA scheme is developed in this paper to mitigate harmonic disturbances in vibration responses and thus enable performing precise modal estimation with uncertainty quantification for wind turbines. The noise robustness, stability, and accuracy of the hybrid OMA scheme are verified through a numerical simulation study. Furthermore, the hybrid OMA scheme is employed to evaluate the structural dynamic properties of a three-bladed 2.0 MW wind turbine for assessing its feasibility in practical applications. The primary objective of this study is to provide a hybrid OMA scheme that can accurately estimate modal parameters of wind turbines and other structures with rotating components.