Wind Farm Characterization

Wind Farm Characterization using Coherent Doppler Lidar

Coherent Doppler lidar measurements are of increasing interest for the wind energy industry. Wind measurements are fundamental inputs for the evaluation of potential energy yield and performance of wind farms. Three-dimensional scanning Doppler lidar may provide a new basis for wind farm site selection, design, and optimization. 3-D coherent Doppler lidar is capable of calculating (Krishnamurthy et al. 2011)

Spatial variation of wind field

3DGM_avg_80m_highterr_foll_windmap_20070607_20070703_noaxis — Figure 1. Terrain-following wind speed at hub height (80 m).

Spatial power density estimates

3D_avg_80m_highterr_foll_powermap_20070607_20070703_noaxis — Figure 2. Terrain-following wind power at hub height (80 m).

Spatial wind speed distribution

Figure12_PDF_various_locations_refertextfile — Figure 3. Spatial Wind Distributions at various location on the domain.

Vertical Profiles of Wind speed

Diurnal_Vertprofile_tower_location — Figure 4: Two hour averaged vertical profiles from lidar, showing high shear observed within the rotor swept region.

Wind Turbine Siting

Figure15_GM_Optimal_75turb_loc — Figure 5. Optimal locations of wind turbines (75) overlaid over averaged wind map. The white circular dots represent locations of wind turbines based on the algorithm. The color bar shows wind speed in ms–1at 80 m hub height.

Tower Validation

Table 1: Tower – Lidar wind speed statistics over the period of observation

Instrument	Mean(ms-1)	Standard Deviation(ms-1)	10 minute RMS Difference(ms-1)
Tower @ 50 m	9.67	3.60	1.18
Lidar @ 50 m	9.61	3.61	1.18

Table 2: Wind Speed RMS difference statistics for various time averaging periods

Wind speed RMS difference	10 minute RMS difference(ms-1)	1 Hour RMS difference (ms-1)	24 hour RMS difference (ms-1)
@ 50 m	1.18	0.72	0.46

Please refer Krishnamurthy et al. 2011 for further details.