The influence of the wind speed profile on wind turbine performance measurements

Abstract

To identify the influence of wind shear and turbulence on wind turbine performance, flat terrain wind profiles are analysed up to a height of 160 m. The profiles' shapes are found to extend from no shear to high wind shear, and on many occasions, local maxima within the profiles are also observed. Assuming a certain turbine hub height, the profiles with hub-height wind speeds between 6 m s −1 and 8 m s −1 are normalized at 7 m s −1 and grouped to a number of mean shear profiles. The energy in the profiles varies considerably for the same hub-height wind speed. These profiles are then used as input to a Blade Element Momentum model that simulates the Siemens 3.6 MW wind turbine. The analysis is carried out as time series simulations where the electrical power is the primary characterization parameter. The results of the simulations indicate that wind speed measurements at different heights over the swept rotor area would allow the determination of the electrical power as a function of an 'equivalent wind speed' where wind shear and turbulence intensity are taken into account. Electrical power is found to correlate significantly better to the equivalent wind speed than to the single point hub-height wind speed. Figure 8. (a): Calculated power curves with fi xed and variable rotational speed. No shear; (b): Calculated power curves with fi xed and variable speed. Extreme shear specifi ed. 246 × 76 mm (500 × 500 DPI) 356 R. Wagner et al. ConclusionsLarge variations have been observed in the wind profi les over a fl at site. The results show that the profi les usually do not follow the logarithmic law; instead, their shape, in the case of fl at terrain, heavily depends upon the atmospheric conditions. These profi les were used as input to a sensitivity analysis concerning the power production as a function of a weighted ('equivalent') wind speed over the whole swept rotor area as compared with the results of the wind speed only at hub height. The results from the simulations indicate that measuring the wind speed at an increased number of points over the whole swept rotor area profi le, would improve the correlation between wind input and power output. These results support the necessity for the introduction of a new defi nition for power performance measurements using a distributed measurement of the wind over the swept rotor area instead of using only the hub-height wind speed.

Evaluation of the wind farm parameterization in the Weather Research and Forecasting model (version 3.8.1) with meteorological and turbine power data

“…Evaluating the performance of other wind-farm layouts in locations with complex terrain is also needed. Modifications in the inflow WS considered by the WFP, for example, considering the rotor equivalent wind speed (REWS) (Wagner et al, 2009), may bring promising improvements. More accurate power forecasts will help shape a more competitive wind-energy industry and further facilitate grid integration of wind energy (MacDonald et al, 2016).…”

Could Crop Height Affect the Wind Resource at Agriculturally Productive Wind Farm Sites?

“…The equivalent wind speed is used to quantify the wind-speed change (m s −1 ). Turbines are organized along the abscissa according to the median inflow hub-height wind speed (m s −1 ) experienced under simulated August 2013 conditions sizes utilizing the equivalent wind speed (U eq ), a metric that represents the wind-speed profile across the rotor-disk in a single number Wagner et al 2009). As a result, the equivalent wind speed is more representative of the momentum available to the wind turbine than the hub-height wind speed during conditions with significant rotor-layer shear.…”

“…The equivalent wind speed, first discussed in Antoniou et al (2009) and Wagner et al (2009), represents the whole rotor-layer wind-speed profile with one concise value. This approach has multiple advantages over using the hub-height wind speed and a separate shear metric.…”

Stokastik sınır analizi kullanarak rüzgâr türbinleri için etkinlik değerlendirmesi

“…[16] Rüzgârın karakteristik özellikleri ve diğer atmosferik veriler de literatürde sıklıkla rüzgâr enerji sistemlerinin performans değerlendirmeleri için kullanılmıştır. Rüzgâr hızının profili [29,30]; rüzgâr hızı, yönü, türbülans ve atmosferik durağanlık ile performans arasındaki ilişki [31]; rüzgâr profili ile ilgili çalışmalara örnek verilebilir. Bunların dışında, Pieralli vd.…”