Investigation of Wake Effects on the Energy Production of Small Wind Turbines

Abstract

This paper examines the impact of natural and man-made obstructions on local wind conditions and the performance of small wind turbines when impacted by wake effects. The rural site used for this research contains three Skystream 3.7 turbines in close proximity to each other and several buildings. A 13 m meteorological tower with wind speed and direction sensors was installed in a nearby open area. An empirical analysis was conducted to provide a comparison of turbine performance and measured wind speed for each turbine as a function of localized disturbances caused by turbine placement. Turbine proximity to nearby buildings was observed to cause an overall reduction in power production, although cases of apparent wind speed-up induced by the buildings, and increased relative power output, were also observed. A reduction in wind turbine power output due to the wake of an adjacent turbine was observed. Overall, the turbine closest to the buildings produced about 10% less energy during the measurement period than the most distant turbine. This study confirmed the importance of careful micrositing of small wind turbines, and the complexity of the flow field near buildings and wind turbines.