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Wind Energy Science The interactive open-access journal of the European Academy of Wind Energy
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Discussion papers
https://doi.org/10.5194/wes-2018-72
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/wes-2018-72
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research articles 02 Jan 2019

Research articles | 02 Jan 2019

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Wind Energy Science (WES).

Lidar Estimation of Rotor-Effective Wind Speed – An Experimental Comparison

Dominique P. Held1,2 and Jakob Mann1 Dominique P. Held and Jakob Mann
  • 1Department of Wind Energy, Technical University of Denmark (DTU), Frederiksborgvej 399, 4000 Roskilde, Denmark
  • 2Windar Photonics A/S, Helgeshøj Alle 16–18, 2630 Taastrup, Denmark

Abstract. Lidar systems have the potential of alleviating structural loads on wind turbines by providing a preview of the incoming wind field to the control system. For a collective pitch controller the important quantity of interest is the rotor-effective wind speed (REWS). In this study, we present a model of the coherence between the REWS and its estimate from continuous-wave nacelle-mounted lidar systems. The model uses the spectral tensor definition of the Mann model. Model results were compared to field data gathered from a 2- and 4-beam nacelle lidar mounted on a wind turbine. The comparison shows close agreement for the coherence and the data fits better to the proposed model than to a model based on the Kaimal turbulence model, which underestimates the coherence. Inflow conditions with larger length scales led to a higher coherence between REWS and lidar estimates than inflow turbulence of smaller length scale. When comparing the two lidar systems, it was shown that the 4-beam lidar is able to resolve small turbulent structures with a higher degree of coherence. Further, the advection speed by which the turbulent structures are transported from measurement to rotor plane can be estimated by 10 minute averages of the lidar estimation of REWS. The presented model can be used as a computationally efficient tool to optimize the position of the lidar focus points in order to maximize the coherence.

Dominique P. Held and Jakob Mann
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Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Dominique P. Held and Jakob Mann
Dominique P. Held and Jakob Mann
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Latest update: 25 Mar 2019
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Short summary
In this study a model of the coherence between turbine and lidar estimated rotor-effective wind speed (REWS) is presented. The model is compared against experimental data from two field test using a 2- and 4-beam nacelle-mounted lidar system on a test turbine. The proposed model agrees better to the field data than previously used models. Also, it was shown that the advection speed can be estimated by the REWS measured by the lidar.
In this study a model of the coherence between turbine and lidar estimated rotor-effective wind...
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