Spatial-temporal analysis of coherent offshore wind field structures measured by scanning Doppler-lidar

The Science of Making Torque from Wind

Valldecabres, L.^1 ; Friedrichs, W.^1 ; Von Bremen, L.^1 ; Kühn, M.^1

University of Oldenburg, Institute of Physics, Ammerländer Heerstraße 136, Oldenburg

26129, Germany^1

关键词: Atmospheric conditions;    Coherent structure;    Different time scale;    Lidar measurements;    Mean-flow directions;    Power fluctuations;    Spatial temporal analysis;    Streamwise directions;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/753/7/072028/pdf
DOI  :  10.1088/1742-6596/753/7/072028

来源: IOP

【 摘 要 】

An analysis of the spatial and temporal power fluctuations of a simplified wind farm model is conducted on four offshore wind fields data sets, two from lidar measurements and two from LES under unstable and neutral atmospheric conditions. The integral length scales of the horizontal wind speed computed in the streamwise and the cross-stream direction revealed the elongation of the structures in the direction of the mean flow. To analyse the effect of the structures on the power output of a wind turbine, the aggregated equivalent power of two wind turbines with different turbine spacing in the streamwise and cross-stream direction is analysed at different time scales under 10 minutes. The fact of considering the summation of the power of two wind turbines smooths out the fluctuations of the power output of a single wind turbine. This effect, which is stronger with increasing spacing between turbines, can be seen in the aggregation of the power of two wind turbines in the streamwise direction. Due to the anti-correlation of the coherent structures in the cross-stream direction, this smoothing effect is stronger when the aggregated power is computed with two wind turbines aligned orthogonally to the mean flow direction.