Journal cover Journal topic
Wind Energy Science The interactive open-access journal of the European Academy of Wind Energy
https://doi.org/10.5194/wes-2017-49
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research articles
27 Nov 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Wind Energy Science (WES).
Establishing a robust testing approach for displacement measurement on a rotating horizontal axis wind turbine
Nadia Najafi and Allan Vesth Wind Energy Department, Technical University of Denmark, Denmark
Abstract. Health monitoring by conventional sensors like accelerometers or strain gauges becomes challenging for large rotating structures due to the feasibility, sensing and data transmission. In addition acceleration measurements have low capability in presenting very small frequencies which happen so often for large structures (For instance frequencies between 0.2 and 0.5 Hz in horizontal axis wind turbines). By contrast the displacement measurement using stereo vision is rapid, non-contacting and also distributed over the structure. The sensors are cheaper and easier to be applied in many places on the object to be measured. Horizontal axis wind turbines are one of the important large rotating structures which need to be measured and monitored in time to prevent damage and failure and the blade tip position is one of the key parameters to measure to prevent blade hitting the turbine tower.

This paper presents a well-defined procedure for measuring the displacement on the components of a rotating horizontal axis wind turbine (HAWT) with stereo photometry. Paper markers have been applied on the rotor and tower of a scaled down HAWT model in the workshop and the displacement measurement method has been demonstrated by measuring displacement during operation. The method is mainly developed in two parts: (1) the camera calibration and (2) tracking algorithm. We introduce an efficient camera calibration method for measurement in the large field of views that has always been a challenge. This method is easy and practical and offers better accuracy compared with 2D traditional camera calibration. The tracking algorithm also worked quite successfully and kept tracking the points during rotation within the measurement time.Finally the accuracy analysis has been conducted and has shown the better accuracy of the new calibration method compared with 2D traditional camera calibration.


Citation: Najafi, N. and Vesth, A.: Establishing a robust testing approach for displacement measurement on a rotating horizontal axis wind turbine, Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2017-49, in review, 2017.
Nadia Najafi and Allan Vesth
Nadia Najafi and Allan Vesth
Nadia Najafi and Allan Vesth

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Short summary
This paper presents a well-defined procedure for measuring the displacement on a HAWT via stereo photometry. The method is demonstrated by measuring displacement during operation of a scaled down turbine model. The method is developed in: (1) camera calibration and (2) tracking algorithm. We introduce an efficient, easy and practical calibration method for measurement in the large field of views that is always a challenge. Tracking algorithm also tracks the markers during rotation successfully.
This paper presents a well-defined procedure for measuring the displacement on a HAWT via stereo...
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