The fault vibration signals of wind turbine are non-linear and non-stationary, thus it is difficult to obtain the obvious fault features. In this study, a multifractal method based on the wavelet transform modulus maxima (WTMM) method is used to investigate the main bearing incipient fault of large scale wind turbine. The real vibration signals are analyzed using the multifractal spectrum. The spectrum of the vibration signals is quantified by spectral characteristics including its range and the Hölder exponent corresponding to the maximum dimension. We find that the range of Hölder exponent of normal bearing is narrower than that of the bearing with incipient fault. And the results also indicate that the fault features are different at various wind turbine rotational frequencies. The results demonstrate that the multifractal spectrum obtained from WTMM method is effective to extract the incipient fault features of main bearing of large scale wind turbine.
Received 01 December 2011Accepted 14 December 2012Published online 07 January 2013
This work was financially supported by National Natural Science Foundation of China (Grant Nos. 50975180 and 51005159), Scientific Research Fund of Liaoning Provincial Education Department (Grant No. L2010401). This work was also supported by Liaoning Engineering Research Center for Vibration and Noise Control.
Article outline: I. INTRODUCTION II. THEORY III. RESULTS AND DISCUSSION IV. CONCLUSION
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