This paper investigates a novel perspective on blind filtering of vibration signals with the purpose of fault detection in rotating machinery. Instead of maximizing a property of the time-domain signal such as kurtosis to find an optimal filter, the sparsity of its envelope spectrum is maximized. The underlying assumption for this approach is that faults of rotating components such as bearings introduce second-order cyclostationary content into the signal. This cyclostationary content manifests itself as discrete peaks in the envelope spectrum (given the speed is stationary). These peaks thus increase the sparsity of the envelope spectrum as a consequence. Therefore this paper derives blind filter formulations that try to filter out a signal with the most sparse envelope spectrum. Blind filters are derived using three different sparsity measures, i.c. l 2 l 1 -norm, Hoyer Index, and spectral negentropy. Key in the iterative optimization procedure is the usage of the Rayleigh quotient to update the filter coefficients. One major advantage of this approach is that no prior information about characteristic fault frequencies of the mechanical components of interest needs to be known. Inspection of simulation and experimental results shows that the proposed approach is a simple yet effective way of tracking faults with a cyclostationary signature.

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Abstract. This paper presents the state-of-the-art technologies and development trends of wind turbine drivetrains – the system that converts kinetic energy of the wind to electrical energy – in different stages of their life cycle: design, manufacturing, installation, operation, lifetime extension, decommissioning and recycling. Offshore development and digitalization are also a focal point in this study. Drivetrain in this context includes the whole power conversion system: main bearing, shafts, gearbox, generator and power converter. The main aim of this article is to review the drivetrain technology development as well as to identify future challenges and research gaps. The main challenges in drivetrain research identified in this paper include drivetrain dynamic responses in large or floating turbines, aerodynamic and farm control effects, use of rare-earth material in generators, improving reliability through prognostics, and use of advances in digitalization. These challenges illustrate the multidisciplinary aspect of wind turbine drivetrains, which emphasizes the need for more interdisciplinary research and collaboration.

Review and comparison of tacholess instantaneous speed estimation methods on experimental vibration dataThe MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Peeters, Cédric et al. "Review and comparison of tacholess instantaneous speed estimation methods on experimental vibration data." Mechanical Systems and Signal Processing 129 (August 20190: 407-436.