Abstract
An operational modal analysis study has been carried out on a 1- kW, vertical-axis wind turbine rotor
blade, using a stereo vision technique. Numerical simulation has also been carried out and results
were compared to classical modal analysis and OMA results. The displacement time series used in the
analysis are very short because of limitations in the image acquisition system. Short time series are
not fully qualified for OMA and analyzing the data needs a proper method. Covariance driven
Stochastic Subspace Identification method (SSI-cov) has been used for short time series like
earthquakes. In the SSI-cov method, a block Toeplitz matrix is formed which contains output
correlation functions. 10 displacement time series have been recorded with 187 Hz sampling rate, and
about 3 time series were chosen to be analyzed. The block Toeplitz matrix of 3 time series are
averaged out and the procedure how to analyse short time series is described in this paper. For OMA
validation, a classical modal analysis is done with signals from accelerometers mounted on the blade.
The blade is exited with a hammer. The natural frequencies are estimated by picking the peaks from
the FRFs (Frequency Response Function) obtained at different points. Finally the natural frequencies
and mode shapes obtained from classical modal analysis and OMA results are compared to numerical
simulations of the blade with COMSOL.
Original language | English |
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Title of host publication | Proceedings of IOMAC'15 |
Publication date | 2015 |
Pages | 645-656 |
ISBN (Print) | 978-84-617-3880-9 |
Publication status | Published - 2015 |
Event | 2015 International Operational Modal Analysis Conference - Gijón, Spain Duration: 10 May 2015 → 14 May 2015 |
Conference
Conference | 2015 International Operational Modal Analysis Conference |
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Country/Territory | Spain |
City | Gijón |
Period | 10/05/2015 → 14/05/2015 |
Keywords
- Stereo vision
- Operational Modal Analysis
- Covariance driven SSI