Single Output and Algebraic Modal Parameters Identification of a Wind Turbine Blade: Experimental Results

This paper describes the evaluation of a single output, online, and time domain modal parameters identification technique based on differential algebra and operational calculus. In addition, an analysis of the frequency response function (FRF) of the system is conducted in a specific set up, emulating its nominal or operational conditions to determine the influence of the non-linearities over the dynamic behavior of the system in those particular magnitudes of deformations; thus, this influence is quantified by a numerical index. This methodology is applied to a wind turbine blade submitted to wind tunnel experiments. The natural frequencies and modal damping ratios of six bending modes associated with the blade are estimated using real-time velocity measurements from one single point of the blade. A comparison with the usual impact hammer modal testing is performed to evaluate and establish the proposed approach’s main contributions. The developed modal parameter identification algorithms are implemented to run into a standard personal computer (PC) where the data acquisition system’s measurements are conditioned and processed. The results show the performance and the fast parametric estimation of the proposed algebraic identification approach.

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A Method of Modal Parameter Identification for Wind Turbine Blade Based on Binocular Dynamic Photogrammetry

Shock and Vibration ◽

10.1155/2019/7610930 ◽

2019 ◽

Vol 2019 ◽

pp. 1-10

Author(s):

Wenyun Wang ◽

Xuejun Li ◽

Anhua Chen

Keyword(s):

Wind Turbine ◽

Turbine Blade ◽

Wind Turbine Blade ◽

Modal Identification ◽

Image Feature ◽

Vibration Measurement ◽

Modal Parameters ◽

Target Point ◽

Identification Algorithm ◽

Modal Parameter

The identification of operational modal parameters of a wind turbine blade is fundamental for online damage detection. In this paper, we use binocular photogrammetry technology instead of traditional contact sensors to measure the vibration of blade and apply the advanced stochastic system identification technique to identify the blade modal frequencies automatically when only output data are available. Image feature extraction and target point tracking (PT) are carried out to acquire the displacement of labeled targets on the wind turbine blade. The vibration responses of the target points are obtained. The data-driven stochastic subspace identification (SSI-Data) method based on the Kalman filter prediction sequence is explored to extract modal parameters from vibration response under unknown excitation. Hankel matrixes are reconstructed with different dimensions, so different modal parameters are produced. Similarity of these modal parameters is compared and used to cluster modes into groups. Under appropriate tolerance thresholds, spurious modes can be eliminated. Experiment results show that good effects and stable accuracy can also be achieved with the presented photogrammetry vibration measurement and automatic modal identification algorithm.

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Modal Parameters Identification Based on Noise Cancellation from Measured Vibration Response Signals

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.50-51.828 ◽

2011 ◽

Vol 50-51 ◽

pp. 828-832

Author(s):

Xing Xian Bao ◽

Cui Lin Li

Keyword(s):

Numerical Study ◽

Noise Cancellation ◽

Vibration Response ◽

Parameters Identification ◽

Low Rank ◽

Modal Parameters ◽

Beam Model ◽

Modal Parameter ◽

Low Rank Approximation ◽

Modal Parameters Identification

Measured vibration response signals are inevitably contaminated with noise when a data acquisition system is used for an experimental measurement. This situation often leads to serious difficulties in identifying the modal parameters with proper accuracy. This paper presents a noise cancellation method for measured impulsive response functions (IRFs) based on structured low rank approximation (SLRA) so as to improve the accuracy of the modal parameters identification. Numerical study of a cantilever beam model is carried out to demonstrate the performance of the proposed method. The results show that this method can remove noise from measured IRFs efficiently, and the modal parameter identifications based on the filtered IRFs are very good.

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Structural Design, Analysis, and Testing of a 10 kW Fabric-Covered Wind Turbine Blade

Energies ◽

10.3390/en13123276 ◽

2020 ◽

Vol 13 (12) ◽

pp. 3276

Author(s):

Dong-Kuk Choi ◽

Bong-Do Pyeon ◽

Soo-Yong Lee ◽

Hak-Gu Lee ◽

Jae-Sung Bae

Keyword(s):

Wind Turbine ◽

Turbine Blade ◽

Wind Turbine Blade ◽

Structural Testing ◽

Modal Testing ◽

Mode Shapes ◽

Variational Asymptotic ◽

Design Loads ◽

Sectional Analysis ◽

Sufficient Strength

Reducing the weight of a wind turbine blade is a major issue. Wind turbines have become larger in size to increase power generating efficiency. The blade has also grown in length to take more wind energy. A fabric-based wind turbine blade, introduced by General Electric Co., reduced the blade weight. In this study, a small fabric-covered blade for a 10 kW wind turbine was developed to verify structural ability. The blade was designed on the cross-section using variational asymptotic beam sectional analysis (VABS), structural analysis was carried out using MSC.Nastran for the design loads. A modal analysis was performed to compare the modal frequency and mode shapes. Static structural testing and modal testing were fulfilled. The analysis results were compared with the testing results. The fabric-covered structure was confirmed to reduce the blade mass with sufficient strength.

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