Dynamic monitoring of wind turbines: case studies onand off-shore

Oliveira, Gustavo; Weijtjens, Wout; Sitter, Gert De; Magalhães, Filipe; Cunha, Álvaro; Caetano, Elsa; Devriendt, Christof

doi:10.1201/b18973-137

Cited by 3 publications

(5 citation statements)

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“…This paper focuses on the development of a vibration‐based monitoring system intended to be installed in the tower of onshore and offshore wind turbines, capable of detecting structural anomalies not only in the tower but also in the foundation and blades. This system, based on the identification of the modal properties of the most important vibration modes of the wind turbine, is considered one of the most reliable techniques to be implemented in a wind turbine and is, in fact, required under certain situations .…”

Section: Introductionmentioning

confidence: 99%

Vibration-based damage detection in a wind turbine using 1 year of data

Oliveira

Magalhães

Cunha

et al. 2018

Struct Control Health Monit

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Summary In the current state of development, it is very hard to remotely evaluate the actual condition of wind turbines structures. This makes it impossible for a wind farm owner to correctly deliberate about the need of retrofitting the current wind turbine structure, as well as to decide about the possible extension of its operating lifetime. Taking into account this problem, this paper introduces the main aspects in the development of a vibration‐based monitoring system for an onshore 2.0‐MW wind turbine based on the identification of the modal properties of the most important vibration modes. Initially, the wind turbine is introduced, as well as the implemented monitoring system. Then, the main steps of the monitoring system are briefly described. A detailed attention is given to the statistical procedure based on regression models used to minimize the influence of operational and environmental effects over the features used to detect structural changes in the wind turbine. Lastly, the suitability of the system to detect damages is thus assessed, through the analysis of three common damage scenarios: onshore foundation damage; damage by scour on an offshore foundation; and blade damage. It is concluded that the system is capable of detecting damage in onshore and offshore foundations, as well as in rotor blades. The most important contribution of the paper is the definition of monitoring framework for damage detection, its implementation, and validation with monitoring data collected during more than 1 year in a utility‐scale wind turbine.

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Section: Introductionmentioning

confidence: 99%

Vibration-based damage detection in a wind turbine using 1 year of data

Oliveira

Magalhães

Cunha

et al. 2018

Struct Control Health Monit

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Section: Introductionmentioning

confidence: 99%

“…The system is based on the continuous tracking of modal properties of the structure (frequency values, modal damping ratios and mode shapes), identified during the different operating conditions of a wind turbine. The strategy adopted for the monitoring system has already proved to be suitable to be installed both in onshore and offshore wind turbines [3].The modal identification of large structures excited by operational conditions, an approach usually named as Operational Modal Analysis (OMA), is a technique widely used in several applications [4]. Some examples of implementation of monitoring systems based on OMA in wind turbines are presented in [5,6].…”

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confidence: 99%

One Year of Continuous Dynamic Monitoring of a Wind Turbine. Structural Integrity and Fatigue Assessment

Cunha¹,

Oliveira²,

Magalhães³

et al. 2015

Proceedings of the 5th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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Abstract. The paper presents recent results from a research project based on a continuous dynamic monitoring of a wind turbine. The monitoring system was developed with the capacity to detect structural abnormalities based on the continuous tracking of the modal properties of wind turbines (natural frequencies, modal damping ratios and mode shapes INTRODUCTIONWind power exploitation has shown a consistent growth both in onshore [1] and offshore installations [2], with increasingly competitive costs. This growth has been reflected in the installation of wind turbines composed by very flexible support structures and with large rotors. Due to these characteristics, wind turbines became very susceptible to vibration problems and, consequently, to fatigue damage problems.This paper presents a continuous dynamic monitoring system, under development by the Laboratory of Vibrations and Structural Monitoring (ViBest, www.fe.up.pt/vibest) of FEUP, with the purpose of identifying structural changes (i.e. damage) and estimating the fatigue damage condition of a wind turbine. The system is based on the continuous tracking of modal properties of the structure (frequency values, modal damping ratios and mode shapes), identified during the different operating conditions of a wind turbine. The strategy adopted for the monitoring system has already proved to be suitable to be installed both in onshore and offshore wind turbines [3].The modal identification of large structures excited by operational conditions, an approach usually named as Operational Modal Analysis (OMA), is a technique widely used in several applications [4]. Some examples of implementation of monitoring systems based on OMA in wind turbines are presented in [5,6].The assessment of fatigue condition through acceleration data records was already investigated by some researchers [7,8]. However, in these works, the authors used the results from modal identification tests to tune a finite element model in order to estimate the stress condition of the structure. This paper presents some results already achieved with the developed dynamic monitoring. Initially, the results obtained with the continuous tracking of the modal properties of the wind turbine during one year are presented. In the second part, an improved methodology to estimate the stress time history of the tower structure is presented, where only the acceleration data, alongside with a simple stiffness matrix of the tower, is used. This methodology is applied to a numerical example using the HAWC2 aeroelastic code [9].

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“…Anyhow, the highest accelerations at the intermediate level are certainly due to the excitation introduced by the blade passage in front of the tower (shadow effect), since the sensor at level +48.392 m is located in a position where the second bending mode of the tower presents its maximum ordinate. The dynamic monitoring system is designed to identify the modal properties of the most important vibration modes of the wind turbine in an automated way [3].…”

Section: Description Of the Wind Turbine And Monitoring Systemmentioning

confidence: 99%

“…The monitoring system is based on Operational Modal Analysis (OMA) techniques [1], in which the modal properties of the structure (natural frequencies, modal damping ratios and mode shapes) are continuously tracked over the different operating conditions of the wind turbine. This strategy has already proven to be suitable to be installed both in onshore and offshore [2].…”

Section: Introductionmentioning

confidence: 99%

Automated modal tracking and fatigue assessment of a wind turbine based on continuous dynamic monitoring

Oliveira

Magalhães

Cunha

et al. 2015

MATEC Web of Conferences

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Abstract. The paper describes the implementation of a dynamic monitoring system at a 2.0 MW onshore wind turbine. The system is composed by two components aiming at the structural integrity and fatigue assessment. The first component enables the continuous tracking of modal characteristics of the wind turbine (natural frequency values, modal damping ratios and mode shapes) in order to detect abnormal deviations of these properties, which may be caused by the occurrence of structural damage. On the other hand, the second component allows the estimation of the remaining fatigue lifetime of the structure based on the analysis of the measured cycles of structural vibration.

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Dynamic monitoring of wind turbines: case studies onand off-shore

Cited by 3 publications

References 1 publication

Vibration-based damage detection in a wind turbine using 1 year of data

Vibration-based damage detection in a wind turbine using 1 year of data

One Year of Continuous Dynamic Monitoring of a Wind Turbine. Structural Integrity and Fatigue Assessment

Automated modal tracking and fatigue assessment of a wind turbine based on continuous dynamic monitoring

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