TY - JOUR
T1 - Modelling and measurements of power losses and turbulence intensity in wind turbine wakes at Middelgrunden offshore wind farm
AU - Barthelmie, Rebecca Jane
AU - Frandsen, Sten Tronæs
AU - Nielsen, Niels Morten
AU - Pryor, S.C.
AU - Rethore, Pierre-Elouan Mikael
AU - Ejsing Jørgensen, Hans
PY - 2007
Y1 - 2007
N2 - Understanding of power losses and turbulence increase due to wind turbine wake interactions in large offshore wind forms is crucial to optimizing wind farm design. Power losses and turbulence increase due to wakes are quantified based on observations from Middel-grunden and state-of-the-art models. Observed power losses due solely to wakes are approximately 10% on average. These are relatively high for a single line of wind turbines due in part to the close spacing of the wind farm. The wind form model Wind Analysis and Application Program (WAsP) is shown to capture wake losses despite operating beyond its specifications for turbine spacing. The paper describes two methods of estimating turbulence intensity. one based on the mean and standard deviation (SD) of wind speed from the nacelle anemometer, the other from mean power output and its SD. Observations from the nacelle anemometer indicate turbulence intensity which is around 9% higher in absolute terms than those derived from the power measurements. For comparison, turbulence intensity is also derived from wind speed and SD from a meteorological mast at the some site prior to wind form construction. Despite differences in the measurement height and period, overall agreement is better between the turbulence intensity derived from power measurements and the meteorological mast than with those derived from data from the nacelle anemometers. The turbulence in wind form model indicates turbulence increase of the order 20% in absolute terms for flow directly along the row which is in good agreement with the observations. Copyright C 2007 John Wiley & Sons, Ltd.
AB - Understanding of power losses and turbulence increase due to wind turbine wake interactions in large offshore wind forms is crucial to optimizing wind farm design. Power losses and turbulence increase due to wakes are quantified based on observations from Middel-grunden and state-of-the-art models. Observed power losses due solely to wakes are approximately 10% on average. These are relatively high for a single line of wind turbines due in part to the close spacing of the wind farm. The wind form model Wind Analysis and Application Program (WAsP) is shown to capture wake losses despite operating beyond its specifications for turbine spacing. The paper describes two methods of estimating turbulence intensity. one based on the mean and standard deviation (SD) of wind speed from the nacelle anemometer, the other from mean power output and its SD. Observations from the nacelle anemometer indicate turbulence intensity which is around 9% higher in absolute terms than those derived from the power measurements. For comparison, turbulence intensity is also derived from wind speed and SD from a meteorological mast at the some site prior to wind form construction. Despite differences in the measurement height and period, overall agreement is better between the turbulence intensity derived from power measurements and the meteorological mast than with those derived from data from the nacelle anemometers. The turbulence in wind form model indicates turbulence increase of the order 20% in absolute terms for flow directly along the row which is in good agreement with the observations. Copyright C 2007 John Wiley & Sons, Ltd.
KW - Vindenergi
U2 - 10.1002/we.238
DO - 10.1002/we.238
M3 - Journal article
SN - 1095-4244
VL - 10
SP - 517
EP - 528
JO - Wind Energy
JF - Wind Energy
IS - 6
ER -