Experimental study on wind speeds in a complex-terrain wind farm and analysis of wake effects

In this paper, wind speed deficits have been quantified based on the field observations from the hilly Shiren wind farm in China. Two lidars have been applied to measure wind speeds in the wind farm. Two clusters of wind turbines in different layout patterns were chosen for the experiments. One cluster was the upstream-and-downstream pattern, which was used to investigate the upstream turbine's wake impact on the downstream turbine. According to the experiment, the wake width of the downstream turbine widened and the largest wind speed deficit decreased gradually in the downstream direction. Meanwhile, the wake centerlines of upstream and downstream wind turbines were subjected to the wind direction and may not be in the same line. The other cluster was the side-by-side pattern, which was to investigate how the wakes and the wake interactions develop downwind of a row of wind turbines. It has been found that huge wind speed deficits existed behind the wind turbines. The wind speeds reduced mostly from 14.4 m/s to 8.0 m/s in the downwind direction and from 12.4 m/s to 4.2 m/s in the crosswind direction. Wind speeds were not stable in the far-wake zone. The wake boundary was not easy to determine as well. When wakes of two adjacent turbines encountering, the interaction effect became complicated. In these experiments, the complex terrain is one of the most important factors that complicates the wake distribution. Therefore, the influence of the terrain shape on wake distribution should be continuously investigated in the future.