Damping estimation of an offshore wind turbine on a monopile foundation

Devriendt, Christof; Jordaens, Pieter Jan; Sitter, Gert De; Guillaume, Patrick

doi:10.1049/iet-rpg.2012.0276

Cited by 71 publications

(69 citation statements)

References 16 publications

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“…In El-Kafafy et al 10 and Devriendt et al, 25 different numbers of time lags taken from the correlation functions have been evaluated and 512 points taken from the correlation functions were found to be a good choice. In Devriendt et al, 26 it was evaluated if 10 min for the length of the time segments used in the continuous monitoring of the offshore wind turbine would be sufficient to identify the modal parameters in a robust way. It is assumed that within a time segment of 10 min, the ambient conditions, for example, wind speeds, stay more or less constant, needed for the OMA time-invariant assumption.…”

Section: Description Of the Implemented Proceduresmentioning

confidence: 99%

Structural health monitoring of offshore wind turbines using automated operational modal analysis

Devriendt

Magalhães

Weijtjens

et al. 2014

Structural Health Monitoring

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143

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This article will present and discuss the approach and the first results of a long-term dynamic monitoring campaign on an offshore wind turbine in the Belgian North Sea. It focuses on the vibration levels and modal parameters of the fundamental modes of the support structure. These parameters are crucial to minimize the operation and maintenance costs and to extend the lifetime of offshore wind turbine structure and mechanical systems. In order to perform a proper continuous monitoring during operation, a fast and reliable solution, applicable on an industrial scale, has been developed. It will be shown that the use of appropriate vibration measurement equipment together with state-of-the art operational modal analysis techniques can provide accurate estimates of natural frequencies, damping ratios, and mode shapes of offshore wind turbines. The identification methods have been automated and their reliability has been improved, so that the system can track small changes in the dynamic behavior of offshore wind turbines. The advanced modal analysis tools used in this application include the poly-reference least squares complex frequency-domain estimator, commercially known as PolyMAX, and the covariance-driven stochastic subspace identification method. The implemented processing strategy will be demonstrated on data continuously collected during 2 weeks, while the wind turbine was idling or parked.

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Section: Description Of the Implemented Proceduresmentioning

confidence: 99%

Structural health monitoring of offshore wind turbines using automated operational modal analysis

Devriendt

Magalhães

Weijtjens

et al. 2014

Structural Health Monitoring

Self Cite

143

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“…The modes in this band are basically the dominant vibration modes of both the tower and the turbine's blades. According to the results of some previous intensive studies [7][8][9][10][11][12] on the identification of the physical vibration modes of the tower, foundation system, and the blades of the instrumented OWT, • The mode shapes together with the resonance frequency values of those modes are shown in Figure 2. Based on the work done in [8], some other modes related to the blades and the drivetrain can be detected in the frequency band 0-2 Hz.…”

Section: Data Validation: Low Frequency-band Analysismentioning

confidence: 99%

Automatic Tracking of the Modal Parameters of an Offshore Wind Turbine Drivetrain System

et al. 2017

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An offshore wind turbine (OWT) is a complex structure that consists of different parts (e.g., foundation, tower, drivetrain, blades, et al.). The last decade, there has been continuous trend towards larger machines with the goal of cost reduction. Modal behavior is an important design aspect. For tackling noise, vibration, and harshness (NVH) issues and validating complex simulation models, it is of high interest to continuously track the vibration levels and the evolution of the modal parameters (resonance frequencies, damping ratios, mode shapes) of the fundamental modes of the turbine. Wind turbines are multi-physical machines with significant interaction between their subcomponents. This paper will present the possibility of identifying and automatically tracking the structural vibration modes of the drivetrain system of an instrumented OWT by using signals (e.g., acceleration responses) measured on the drivetrain system. The experimental data has been obtained during a measurement campaign on an OWT in the Belgian North Sea where the OWT was in standstill condition. The drivetrain, more specifically the gearbox and generator, is instrumented with a dedicated measurement set-up consisting of 17 sensor channels with the aim to continuously track the vibration modes. The consistency of modal parameter estimates made at consequent 10-min intervals is validated, and the dominant drivetrain modal behavior is identified and automatically tracked.

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“…The damping ratio of the two modes is found to be approximately ζ = 0.0020 with soil damping representing approximately one‐fifth (0.0004), while the remaining amount (0.0016) comes from proportional damping in the numerical model. In order to increase this to a more realistic value, soil damping is simply calibrated to obtain a total damping ratio in both modes slightly larger than 0.01, which corresponds to experimentally predicted values in the literature . The resulting values for the natural frequencies and damping ratios are presented in Table .…”

Section: Damping Of Offshore Wind Turbine Tower Vibrationsmentioning

confidence: 99%

Active tuned mass damper for damping of offshore wind turbine vibrations

2016

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An active tuned mass damper (ATMD) is employed for damping of tower vibrations of fixed offshore wind turbines, where the additional actuator force is controlled using feedback from the tower displacement and the relative velocity of the damper mass. An optimum tuning procedure equivalent to the tuning procedure of the passive tuned mass damper combined with a simple procedure for minimizing the control force is employed for determination of optimum damper parameters and feedback gain values. By time domain simulations conducted in an aeroelastic code, it is demonstrated that the ATMD can be used to further reduce the structural response of the wind turbine compared with the passive tuned mass damper and this without an increase in damper mass. A limiting factor of the design of the ATMD is the displacement of the damper mass, which for the ATMD, increases to compensate for the reduction in mass. Copyright © 2016 John Wiley & Sons, Ltd.

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Damping estimation of an offshore wind turbine on a monopile foundation

Cited by 71 publications

References 16 publications

Structural health monitoring of offshore wind turbines using automated operational modal analysis

Structural health monitoring of offshore wind turbines using automated operational modal analysis

Automatic Tracking of the Modal Parameters of an Offshore Wind Turbine Drivetrain System

Active tuned mass damper for damping of offshore wind turbine vibrations

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