Quantifying the Impact of Wind Turbine Wakes on Power Output at Offshore Wind Farms

R. J. Barthelmie Atmospheric Science Program, College of Arts and Sciences, Indiana University, Bloomington, Indiana
Risoe DTU Laboratory for Sustainable Energy, Roskilde, Denmark

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S. C. Pryor Atmospheric Science Program, College of Arts and Sciences, Indiana University, Bloomington, Indiana
Risoe DTU Laboratory for Sustainable Energy, Roskilde, Denmark

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S. T. Frandsen Risoe DTU Laboratory for Sustainable Energy, Roskilde, Denmark

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K. S. Hansen Mechanical Engineering, Danish Technical University, Kongens, Lyngby, Denmark

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J. G. Schepers Energy Research Centre of the Netherlands, Petten, Netherlands

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K. Rados National Technical University of Athens, Zografou, Athens, Greece

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W. Schlez * Garrad Hassan Deutschland GmbH, Oldenburg, Germany

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A. Neubert * Garrad Hassan Deutschland GmbH, Oldenburg, Germany

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L. E. Jensen DONG Energy, Fredericia, Denmark

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S. Neckelmann Vattenfall, Fredericia, Denmark

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Abstract

There is an urgent need to develop and optimize tools for designing large wind farm arrays for deployment offshore. This research is focused on improving the understanding of, and modeling of, wind turbine wakes in order to make more accurate power output predictions for large offshore wind farms. Detailed data ensembles of power losses due to wakes at the large wind farms at Nysted and Horns Rev are presented and analyzed. Differences in turbine spacing (10.5 versus 7 rotor diameters) are not differentiable in wake-related power losses from the two wind farms. This is partly due to the high variability in the data despite careful data screening. A number of ensemble averages are simulated with a range of wind farm and computational fluid dynamics models and compared to observed wake losses. All models were able to capture wake width to some degree, and some models also captured the decrease of power output moving through the wind farm. Root-mean-square errors indicate a generally better model performance for higher wind speeds (10 rather than 6 m s−1) and for direct down the row flow than for oblique angles. Despite this progress, wake modeling of large wind farms is still subject to an unacceptably high degree of uncertainty.

Corresponding author address: R. J. Barthelmie, Multidisciplinary Science Building II, 702 North Walnut Grove, Indiana University, Bloomington, IN 47405. Email: rbarthel@indiana.edu

Abstract

There is an urgent need to develop and optimize tools for designing large wind farm arrays for deployment offshore. This research is focused on improving the understanding of, and modeling of, wind turbine wakes in order to make more accurate power output predictions for large offshore wind farms. Detailed data ensembles of power losses due to wakes at the large wind farms at Nysted and Horns Rev are presented and analyzed. Differences in turbine spacing (10.5 versus 7 rotor diameters) are not differentiable in wake-related power losses from the two wind farms. This is partly due to the high variability in the data despite careful data screening. A number of ensemble averages are simulated with a range of wind farm and computational fluid dynamics models and compared to observed wake losses. All models were able to capture wake width to some degree, and some models also captured the decrease of power output moving through the wind farm. Root-mean-square errors indicate a generally better model performance for higher wind speeds (10 rather than 6 m s−1) and for direct down the row flow than for oblique angles. Despite this progress, wake modeling of large wind farms is still subject to an unacceptably high degree of uncertainty.

Corresponding author address: R. J. Barthelmie, Multidisciplinary Science Building II, 702 North Walnut Grove, Indiana University, Bloomington, IN 47405. Email: rbarthel@indiana.edu

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  • Ainslie, J. F., 1988: Calculating the flow field in the wake of wind turbines. J. Wind Eng. Ind. Aerodyn., 27 , 213224.

  • Barthelmie, R. J., and Coauthors, 2004: Efficient development of offshore windfarms (ENDOW): Modelling wake and boundary layer interactions. Wind Energy, 7 , 225245.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Barthelmie, R. J., Folkerts L. , Rados K. , Larsen G. C. , Pryor S. C. , Frandsen S. , Lange B. , and Schepers G. , 2006: Comparison of wake model simulations with offshore wind turbine wake profiles measured by sodar. J. Atmos. Oceanic Technol., 23 , 888901.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Barthelmie, R. J., Badger J. , Pryor S. C. , Hasager C. B. , Christiansen M. B. , and Jørgensen B. H. , 2007a: Wind speed gradients in the coastal offshore environment: Issues pertaining to design and development of large offshore wind farms. Wind Eng., 31 , 369382.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Barthelmie, R. J., Frandsen S. T. , Nielsen N. M. , Pryor S. C. , Rethore P. E. , and Jørgensen H. E. , 2007b: Modelling and measurements of power losses and turbulence intensity in wind turbine wakes at Middelgrunden offshore wind farm. Wind Energy, 10 , 217228.

    • Search Google Scholar
    • Export Citation
  • Barthelmie, R. J., Frandsen S. T. , Rethore P. E. , and Jensen L. , 2007c: Analysis of atmospheric impacts on the development of wind turbine wakes at the Nysted wind farm. Proc. European Offshore Wind Conf., Berlin, Germany, European Wind Energy Association, PO.36. [Available online at http://www.eow2007proceedings.info/allfiles2/132_Eow2007fullpaper.pdf].

    • Search Google Scholar
    • Export Citation
  • Barthelmie, R. J., and Coauthors, 2007d: Flow and wakes in complex terrain and offshore: Model development and verification in UpWind. Proc. European Wind Energy Conf., Milan, Italy, European Wind Energy Association, Bl3.200. [Available online at http://www.ewec2007proceedings.info/allfiles2/108_Ewec2007fullpaper.pdf].

    • Search Google Scholar
    • Export Citation
  • Barthelmie, R. J., and Coauthors, 2009: Modelling and measuring flow and wind turbine wakes in large wind farms offshore. Wind Energy, 12 , 431444. doi:10.1002/we.348.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Cleve, J., Grenier M. , Enevoldsen P. , Birkemose B. , and Jensen L. , 2009: Model-based analysis of wake-flow data in the Nysted offshore wind farm. Wind Energy, 12 , 125135. doi:10.1002/we.314.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Crespo, A., Hernandez J. , and Frandsen S. , 1999: Survey of modelling methods for wind turbine wakes and wind farms. Wind Energy, 2 , 124.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Dahlberg, , and Thor S-E. , 2009: Power performance and wake effects in the closely spaced Lillgrund offshore wind farm. Extended Abstracts, European Offshore Wind Conf., Stockholm, Sweden, European Wind Energy Association, AT4.4. [Available online at http://www.eow2009proceedings.info/programme_test/ewec.php?id2=106&id=&ordre=4].

    • Search Google Scholar
    • Export Citation
  • Frandsen, S. T., and Thøgersen M. L. , 1999: Integrated fatigue loading for wind turbines in wind farms by combining ambient turbulence and wakes. Wind Eng., 23 , 327339.

    • Search Google Scholar
    • Export Citation
  • Frandsen, S. T., Barthelmie R. , Pryor S. , Rathmann O. , Larsen S. , Højstrup J. , and Thøgersen M. , 2006: Analytical modelling of wind speed deficit in large offshore wind farms. Wind Energy, 9 , 3953.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Frandsen, S. T., and Coauthors, 2007: Summary report: The shadow effect of large wind farms: Measurements, data analysis and modeling. Risø Rep. Risø-R-1615(EN), 34 pp.

    • Search Google Scholar
    • Export Citation
  • Frandsen, S. T., and Coauthors, 2009: The making of a second-generation wind farm efficiency model-complex. Wind Energy, 12 , 445458.

  • International Energy Agency, cited. 2008: IEA wind energy annual report 2007. 286 pp. [Available online at http://www.ieawind.org/AnnualReports_PDF/2007/2007%20IEA%20Wind%20AR.pdf].

    • Search Google Scholar
    • Export Citation
  • Jensen, L., 2004: Wake measurements from the Horns Rev wind farm. Proc. European Wind Energy Conf., London, United Kingdom, European Wind Energy Association.

    • Search Google Scholar
    • Export Citation
  • Jensen, N. O., 1983: A note on wind turbine interaction. Risø Rep. Risø-M-2411, 16 pp.

  • Katic, I., Højstrup J. , and Jensen N. O. , 1986: A simple model for cluster efficiency. Proc. European Wind Energy Association Conf. and Exhibition, Rome, Italy, European Wind Energy Association, 407–409.

    • Search Google Scholar
    • Export Citation
  • Magnusson, M., Rados K. G. , and Voutsinas S. G. , 1996: A study of the flow down stream of a wind turbine using measurements and simulations. Wind Eng., 20 , 389403.

    • Search Google Scholar
    • Export Citation
  • Manwell, J. F., McGowan J. , and Rogers A. L. , 2002: Wind Energy Explained: Theory, Design and Application. John Wiley and Sons, 590 pp.

  • Mortensen, N. G., Heathfield D. N. , Myllerup L. , Landberg L. , and Rathmann O. , 2005: Wind atlas analysis and application program: WAsP 8 help facility. Risø National Laboratory, Roskilde, Denmark.

    • Search Google Scholar
    • Export Citation
  • Politis, E. S., Rados K. , Prospathopoulos J. M. , Chaviaropoulos P. K. , and Zervos A. , 2009: CFD modeling issues of wind turbine wakes under stable atmospheric conditions. Proc. European Wind Energy Conf., Marseille, France, European Wind Energy Association, PO.163. [Available online at http://www.ewec2009proceedings.info/allfiles2/564_EWEC2009presentation.pdf].

    • Search Google Scholar
    • Export Citation
  • Quarton, D., and Ainslie J. , 1990: Turbulence in wind turbine wakes. Wind Eng., 14 , 1523.

  • Rathmann, O., Barthelmie R. J. , and Frandsen S. T. , 2006: Turbine wake model for wind resource software. Proc. European Wind Energy Conf., Athens, Greece, European Wind Energy Association, BL3.313. [Available online at http://130.226.56.153/rispubl/art/2007_179_paper.pdf].

    • Search Google Scholar
    • Export Citation
  • Schepers, J. G., 2003: ENDOW: Validation and improvement of ECN’s wake model. Energy Research Center for the Netherlands Rep. ECN-C–03-034, 113 pp.

    • Search Google Scholar
    • Export Citation
  • Schlez, W., and Neubert A. , 2009: New developments in large wind farm modelling. Proc. European Wind Energy Conf., Marseilles, France, European Wind Energy Association, PO.167. [Available online at http://www.ewec2009proceedings.info/allfiles2/686_EWEC2009presentation.pdf].

    • Search Google Scholar
    • Export Citation
  • Sørensen, T., Nielsen P. , and Thøgersen M. T. , 2006: Recalibrating wind turbine wake model parameters—Validating the wake model performance for large offshore wind farms. Proc. European Wind Energy Conf. and Exhibition, Athens, Greece, European Wind Energy Association, BL3.114. [Available online at http://www.ewec2006proceedings.info/allfiles2/0693_Ewec2006fullpaper.pdf].

    • Search Google Scholar
    • Export Citation
  • Wagner, A., 2009: Offshore wind energy developments and future prospects new opportunities for the maritime industry. Maritime Clusters in Landlocked Countries Conf. and Workshop, Prague, Czech Republic, European Commission. [Available online at http://www.eu2009.cz/event/1/3312/].

    • Search Google Scholar
    • Export Citation
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