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Modelling the impact of wakes on power output at Nysted and Horns Rev R.J. Barthelmie, Indiana University USA/Risoe DTU DK K. Hansen, DTU Denmark S.T. Frandsen, O. Rathmann, RISOE DTU Denmark G. Schepers ECN, Netherlands K. Rados, NTUA, Greece W. Schlez, A. Neubert, GH, Germany L.E. Jensen, DONG Energy, Denmark S. Neckelmann, Vattenfall, Denmark Funding: NSF CBET-0828655, EU UPWIND # SES6 019945 EU POWWOW #SES6 019898 Data: DONG Energy A/S & Vattenfall AB (Horns Rev), Vattenfall and E. On Sweden (Nysted) Modelling wakes in the UpWind project Problems Solutions 1. Preliminary analysis of wake power losses in large offshore wind farms larger than expected. Amended but high uncertainty 2. First v. large wind farms on land 3. Resources and wakes difficult to model in complex terrain 4. Multiple wind farms developed in same area 1. New parameters and/or next generation of wake models able to account for ‘deep array’ effect 2. (Assess the magnitude of the issue onshore) 3. Develop, apply and evaluate CFD 4. Assess, develop and evaluate models for whole wind farm modelling Data In agreement with data owners some wind farm data have been made available Access is open and free (registration necessary) Offshore wake data from • • • • Vindeby Middelgrunden Horns Rev Nysted (in proc) Data processed into case studies for Horns Rev, Nysted (performance remains confidential) Access /registration details: http://mypage.iu.edu/~rbarthel/wakeslab.html Wake models used in this project Name Company Type Commercial/ Research WAsP Risø DTU Engineering C Windfarmer GH Ainslie C Risø Flow Risø DTU Under development R Wakefarm ECN Parabolised CFD C/R CENER Fluent CENER CFD R NS FLow CRES CFD R NTUA NTUA CFD R Offshore wind farms Wind farm Nysted Horns Rev Owner DONG Energy (80%) E.On Sweden (20%) DONG Energy (40%) Vattenfall (60%) Turbine number 72 80 Turbine Siemens 2.3 MW Vestas 2 MW 57.5 Turbine type Active stall, 2-speed Latitude(° N) 57.0 56.5 56.0 Pitch, variable speed 55.5 Rotor diam (D) 82.4 m Horns Rev 80 m 55.0 Hub-height 69 m Nysted 70 m 54.5 Array 8 (E-W) x 9 (N-S) 10 (E-W) x 8 (N-S) Dist. between turbines 10.3 D (E-W) & 5.8 D (N-S) 7 D (E-W & N-S) Rated capacity 165.6 MW 160 MW Annual prod. 595 GWh 600 GWh Year comm. 2003 2002 Water depth 6-10 m 6-14 m Distance land 10 km (closest) 14-20 km 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 13.0 Longitude (° E) http://earthobservatory.nasa.gov/IOTD/view.php?id=3389 Horns Rev and Nysted layouts Horns Rev 7D x 7D Nysted 10.5D x 5.8D Data comparison Data from 2004-2006 Nysted, 2005 Horns Rev Selection on: • • • • wind speed ±0.5 ms-1 direction ±2.5º all turbines working in row all turbines working in neighbouring rows • two subsequent observations for stationarity Gives relatively few observations in each category Data differences mainly due to spacing? 1 0.8 0.8 0.6 0.6 0.4 0.2 Normalised power 1 2 3 4 5 6 7 8 9 10 1 1 0.8 0.6 0.6 0.4 0.2 0.4 26525o 0.2 Normalised power 1 2 3 4 5 6 7 8 9 10 1 0.8 0.8 0.6 0.6 0.2 27525o Normalised power 1 2 3 4 5 6 7 8 9 10 270±2.5o 0.4 0.2 280±2.5o 0.6 0.4 0.2 285±2.5o 1 2 3 4 5 6 7 8 9 10 Turbine 0.8 0.8 0.6 0.6 0.4 Observations WAsP Windfarmer ECN NTUA 0.4 263±2.5o 0.2 268±2.5o 0.2 1 2 3 4 5 6 7 8 1 1 1 0.8 0.8 0.6 0.6 0.4 2 3 4 5 6 7 8 4 5 6 7 8 5 6 7 8 0.4 2732.5o 0.2 1 2 3 4 5 6 7 8 1 1 0.8 0.8 0.6 0.6 0.4 1 2 3 2 3 0.4 2832.5o 0.2 278±2.5o 0.2 1 1 2 3 4 5 6 7 8 9 10 1 0.8 1 1 2 3 4 5 6 7 8 9 10 1 0.4 1 1 2 3 4 5 6 7 8 9 10 1.2 0.8 260±2.5o Normalised power 0.2 255±2.5o Normalised power 0.4 Normalised power 1 Normalised power Normalised power Model comparison at Horns Rev and Nysted 0.2 4 5 6 7 8 288±2.5o 1 2 3 4 1 0.8 Observations WAsP Windfarmer ECN 0.6 0.4 0.2 293±2.5o 1 2 3 4 5 Turbine 6 7 8 Model comparison at Horns Rev and Nysted Exact row, narrow directions • • • Seems to be a special case Agreement on wake behaviour at Horns Rev and Nysted Model agreement within ±10% Cross row angles • • Asymmetry in obs. and models Larger uncertainty ER ER+10º Model comparison at Horns Rev and Nysted Consistency improved in model results High degree of uncertainty • Differences between models • Data issues • Lower wind speeds Ongoing issues • Asymmetry around central row • Developing quantitative methods of evaluation e.g. efficiency • Stability Stability at Nysted 1.2 All Stable Unstable Neutral 1 1 0.9 Normalised power at 2nd turbine Normalised power output (kW) . 0.8 0.6 0.4 0.8 0.7 Neutral Stable Unstable 0.6 8<U<10 m/s Turbines in row 5 operating0.5 s.d. 0.2 0.5 0 2 4 6 8 Turbine number Results from Barthelmie et al. 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Offshore Wind 2007 -9 -6 -3 0 3 Distance from wake centre in deg 6 9 Summary and future work • Objective Reducing uncertainty in predicting power losses from wakes • UpWind project Provides platform for undertaking model evaluation & data sharing • Progress made Data analysis and modelling Wakes can be modelled with appropriate parameters • Future Physical understanding of wake processes within and downwind wind farms Other UpWind wake presentations and posters WIND TURBINE WAKE VIRTUAL LABORATORY: PROPOSAL FOR A NEW COLLABORATION Rebecca Barthelmie, Indiana University, United States & Risø DTU, Denmark PO.155 APPLYING FLOW MODELS OF DIFFERENT COMPLEXITY FOR ESTIMATION OF WIND TURBINE WAKES Søren Ott, Risø DTU, Denmark PO.156 A FAST PARAMETERIZED WAKE-MODEL FOR LARGE WIND FARMS Ole Steen Rathmann, Risø DTU, Denmark PO.161 CFD MODELING ISSUES OF WIND TURBINE WAKES UNDER STABLE ATMOSPHERIC CONDITIONS Evangelos Politis, Centre for Renewable Energy Sources (CRES), Greece PO.163 NEW DEVELOPMENTS IN LARGE WIND FARM MODELLING Wolfgang Schlez, Garrad Hassan Deutschland GmbH, Germany CFD MODELLING OF THE INTERACTION BETWEEN THE SURFACE BOUNDARY LAYER AND ROTOR WAKE Daniel Cabezón, CENER, Spain PO.167