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Title. Comparison of the ZephIR Wind-LiDAR to Classical Cup Measurements On- and Offshore Detlef Kindler WINDTEST Kaiser-Wilhelm-Koog GmbH Andy Oldroyd Oldbaum Services Ltd. EWEC 2007, Milan, Italy “ Advances in measuring methods ” Technical Track - Session DT2, 10 Mai 2007

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  1. Title Comparison of the ZephIR Wind-LiDAR to Classical Cup MeasurementsOn- and OffshoreDetlef KindlerWINDTEST Kaiser-Wilhelm-Koog GmbHAndy OldroydOldbaum Services Ltd. EWEC 2007, Milan, Italy “Advances in measuring methods” Technical Track - Session DT2, 10 Mai 2007 supported by: EU-Project DOWNVInD - Partners

  2. Motivation • Onshore and Offshore Assesment Campaign 5M met.mast site, Brunsbüttel Offshore platform FINO-1, Germany • Assessment Results Availability Data quality • Wind Speed Profiles • Turbulence Comparisons • Summary Outline

  3. 5M Offshore Remote Sensing (LiDAR) asprimary wind resource monitoring method for Beatrice Windfarm Demonstrator Project • Assessment of capabilities of the ZephIR Wind LiDAR • Suitability for offshore purposes Motivation

  4. Acceptance criteria for the ZephIR being used as the primary wind monitioring method on the Beatrice Alpha platform:  Availability: > 95 % (system & data) Data quality: wind speed relative to cups (4 to 16 m/s) linear regression through origin Y = mx + b (i.e. with b==0) 0.97 < m < 1 R2 > 0.95 Acceptance Criteria

  5. 120 m 70 m 90 m 60 m • 3 month campaign: 30 Sep 2005 until 5 Jan 2006 • Fairly large distance to met.mast • Complex surrounding: industrial plants, wind turbines 5M Onshore Test

  6. ZephIR 103 m 81 m 61 m • North Sea, 45 km North of German island Borkum • Annual mean wind speed on 100 m: ~ 10 m/s • Prevailing wind dir.: SW • Mast top height: 103 m • ZephIR height: 25 m • 5 Month campaignMarch to July 2006 • ZephIR close to mast ( ~ 10 m) • No disturbanceby met.mast on LiDAR FINO-1 Offshore Test

  7. Onshore – 5M Met.-Mast Site Overall System Availability:99.6 % Overall Data Availability (10-Min.-Avg.):95.2 % Offshore – FINO 1 Platform Overall System Availability:100.0 % Overall Data Availability (10-Min.-Avg.):99.6 % Availability

  8. 120m Slope: m = 0.95 Regr. coefficient: R2 = 0.96 90m Slope: m = 0.97 Regr. coefficient: R2 = 0.97 WS Regressions Onshore

  9. LiDAR Cup Height: 103 (78) m WS range: 2 to 23 m/s Regression: m = 0.97 R2 = 0.99 WS Comparison Offshore

  10. 81 (56) m 61 (36) m Slope: m = 0.97 Regr. coefficient: R2 = 0.99 Slope: m = 0.98 Regr. coefficient: R2 = 1.00 WS Regressions Offshore

  11. WS Regression Results

  12. Cup LiDAR WS Weibull Distribution

  13. Good performance onshore despite terrain complexity ZephIR passed acceptance • Offshore test FINO-1, similar environment as on Beatrice better correlation offshore than onshore • Main result WS deviation from Cups < 3% Availability close to 100% (NO weather dependence) good handling, easy to install • System passed acceptance onshore and offshore installation on Beatrice in Nov. 2006 stand-alone operation for wind monitoring, good performance since Note: 1st Beatrice 5M wind turbine connected since last Tue, 8th May 2007 Assessment Summary

  14. Wind Speed Profiles – Vertical Sampling: Cup: point measurement LiDAR: “average” over vertical range change of probing length with height Source: RISOE WS Profiles

  15. WS Profiles Offshore

  16. Wind Speed Turbulence (10 minute averaging) TRB = WS-STD / WS-Mean [%] Sampling Cup: 1 Hz  600 values Sampling LiDAR: 3 sec for individual height scan 5 consecutive heights  max. 40 values WS Turbulence

  17. Onshore Offshore WS Standard Deviation

  18. Onshore Offshore Turbulence vs. WS

  19. Onshore Offshore Turbulence WS Binned

  20. Differences in mast measurements • Cup type Thies-1st-Class (On-),Vector (Offshore) • STD calculation1Hz, 600 values, 10 Min.-STD1Hz, 60 values, 1 Min.STD  10 Min.STD (according to IEC) Other differences onshore vs. offshore • Terrain, obstacles • Surface roughness • Atmospheric stability  impact on dominant turbulence length scales Character of volume measuring technique more pronounced onshore … Turbulence

  21. Assessment campaign: good availability and data quality onshore & offshore Absolute wind speed accuracy is close to that of cups (with high quality calibrations) WS profiles: good resemblance to cup / met.mast results ZephIR turbulence measures compare to cup turbulence measures onshore and offshore, differently …? Outlook • More operational experiences are needede.g. complex terrain applications • Reproducibility device to device needs to be proven • Best practice application procedures – testing / calibration • Work towards standard acceptance / incorporation (e.g. IEC) Overall Summary / Outlook

  22. Thanks

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