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COMPARISON OF EXTREME LOAD EXTRAPOLATIONS USING MEASURED AND CALCULATED LOADS

COMPARISON OF EXTREME LOAD EXTRAPOLATIONS USING MEASURED AND CALCULATED LOADS. Johan Peeringa and Erik Korterink EWEC 2009, 18 March 2009, Marseille. Content. We@Sea project on extreme load extrapolation ECN Wind turbine Test site Wieringermeer (EWTW) Extreme load statistics

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COMPARISON OF EXTREME LOAD EXTRAPOLATIONS USING MEASURED AND CALCULATED LOADS

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  1. COMPARISON OF EXTREME LOAD EXTRAPOLATIONS USING MEASURED AND CALCULATED LOADS Johan Peeringa and Erik Korterink EWEC 2009, 18 March 2009, Marseille

  2. Content • We@Sea project on extreme load extrapolation • ECN Wind turbine Test site Wieringermeer (EWTW) • Extreme load statistics • Results of measured free stream extreme loads • Calculation of loads in wake conditions • Comparison of measured and calculated extreme loads • Conclusions

  3. Project • Aim is validation of extreme value models by comparing extreme loads based on measurements and calculations.

  4. Research turbines numbered from 5 (most Westerly) to 9 (most Easterly) Wind farm line: 95-275 degrees MM3 at 3.5 D and 315 degrees from turbine 5 MM3 at 2.5D and 31 degrees from turbine 6 2000 Meteo mast 3 1000 0 - 2000 - 1000 0 1000 2000 Meteo mast 1 Meteo mast 2 - 1000 Research turb NM52 Meteo mast Proto types Single WEC - 2000 1 km

  5. Statistical model The long-term response distribution is the integration of the short-term response distribution, conditional on the wind speed (and turbulence), over all wind speeds.

  6. Method and distributions • L-moment http://www.research.ibm.com/people/h/hosking/lmoments.html • Generalized Extreme Value (GEV) • Gumbel • Lognormal • Weibull

  7. Free stream measured loads u= 15.5 m/s & t =1.75 m/s

  8. Free stream loads for different number of measurements used

  9. Calculation of wake conditions • ECNWakeFarm • SWIFTwake • PHATAS

  10. Comparison of empirical load distributions

  11. Free stream condition

  12. Partial wake condition

  13. Full stream condition

  14. Conclusions • For free stream measured loads the GEV, lognormal and Weibull distribution show good agreement with the empirical distribution. • For the free stream measured loads 50 measurements are sufficient for the estimation of the distribution parameters. • Calculated extreme flat blade root bending moments are smaller than the measured ones for all conditions at 15.5 m/s. • Calculation methods for wake conditions should be improved.

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