Cepstrum-based operational modal analysis of wind turbines with and without external flaps

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Department of Civil, Environmental, and Geospatial Engineering


Operational modal analysis (OMA) cannot be directly applied on an operating wind turbine due to the presence of the harmonics in the output signals. This paper develops a modified cepstral notch lifter to remove harmonics. A combined cepstrum-based OMA is conducted on a wind turbine model taking into account the aero-servo-elastic characteristics to evaluate the applicability and performance of the modified cepstral notch lifter by comparing the modal parameters extracted from the OMA and the ones obtained from a direct linearization eigenvalue analysis. The results show that the modal frequencies can be reasonably estimated. At last, this method is applied on a wind turbine with external flaps to study the flap effects on the structural dynamics of the wind turbine.

Publisher's Statement

Copyright 2018 Published by AIP Publishing. Publisher’s version of record: https://doi.org/10.1063/1.5037782