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Wind Energy Science The interactive open-access journal of the European Academy of Wind Energy
© Author(s) 2017. This work is distributed under
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Research articles
14 Jun 2017
Review status
This discussion paper is a preprint. A revision of this manuscript was accepted for the journal Wind Energy Science (WES) and is expected to appear here in due course.
Using wind speed from a blade-mounted flow sensor for power and load assessment on modern wind turbines
Mads M. Pedersen, Torben J. Larsen, Helge Aa. Madsen, and Gunner Chr. Larsen Wind Energy Department, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde, Denmark
Abstract. In this paper an alternative method to evaluate power performance and loads on wind turbines using a blade-mounted flow sensor is investigated. The hypothesis is that the wind speed measured at the blades has a high correlation with the power and loads such that a power or load assessment can be performed from a few hours or days of measurements.

In the present study a blade-mounted five-hole pitot tube is used as the flow sensor as alternative to the conventional approach, where the reference wind speed is either measured at a nearby met mast or on the nacelle using LiDAR technology or cup anemometers. From the flow sensor measurements, an accurate estimate of the wind speed at the rotor plane can be calculated. This wind speed is disturbed by the presence of the wind turbine, and it is therefore different from the free-flow wind speed. However, the recorded wind speed has a high correlation with the actual power production as well as the flap-wise loads as it is measured close to the blade where the aerodynamic forces are acting.

Conventional power curves are based on at least 180 hours of 10 minute mean values, but using the blade-mounted flow sensor both the observation average time and the overall assessment time can potentially be shortened. The basis for this hypothesis is that the sensor is able to provide more observations of with higher accuracy, as the sensor follows the orientation of the rotor and because of the high correlation between the flow at the blades and the power production. This is the research question addressed in this paper.

The method is first tested using aero-elastic simulations where also the dependence of radial position and effect of multiple blade-mounted flow sensors is investigated. Next the method is evaluated on basis of full-scale measurements of a pitch-regulated, variable-speed 3.6MW wind turbine.

It is concluded that the wind speed derived from the blade-mounted flow sensor is highly correlated with the power and flap-wise bending moment, and that the method has advantages over the traditional approach where the met mast wind speed is used as reference, e.g. the capability of measuring the shear, veer and turbulence. The aero-elastic simulations show that the assessment time can be reduced, but this reduction cannot be confirmed from the current measurement database due to practical issues and circumstances, i.a. sensor problems. Measuring the wind speed at the rotor plane also has a price as the wind speed is affected by the induction which may be sensitive to the changes you want to evaluate, e.g. different vortex generator configurations. Furthermore it is concluded that it requires a robust instrument and measurement system to obtain accurate and reliable wind speed recordings from pitot tube measurements.

Citation: Pedersen, M. M., Larsen, T. J., Madsen, H. Aa., and Larsen, G. Chr.: Using wind speed from a blade-mounted flow sensor for power and load assessment on modern wind turbines, Wind Energ. Sci. Discuss.,, in review, 2017.
Mads M. Pedersen et al.
Interactive discussionStatus: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version      Supplement - Supplement
RC1: 'Paper Review', Anonymous Referee #1, 21 Jul 2017 Printer-friendly Version 
AC1: 'Reply to “Paper review”', Mads Pedersen, 29 Aug 2017 Printer-friendly Version 
RC2: 'Comments by reviewer (see also supplement pdf)', V.A. Riziotis, 01 Aug 2017 Printer-friendly Version Supplement 
AC2: 'Reply to 'Comments by reviewer'', Mads Pedersen, 29 Aug 2017 Printer-friendly Version 
Mads M. Pedersen et al.
Mads M. Pedersen et al.


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