The influence of atmospheric stability on wind turbine performance: A quantitative study using measurement from SCADA system and mast

Abstract

In the wind resource assessment, to estimate the energy potential of a site, engineers use the manufacturer power curve. This power curve is an ideal relationship between the wind speed of an ideal wind flow and the output power of the designed turbine. The industry standard IEC 61400-12-1 establishes some requirements to measure such power curves. In the real condition, with the same value of wind speed, a large range of output power could be obtained. This difference may be caused by atmospheric stability, which affects wind profiles across the turbine blades. This study focuses on the influence of atmospheric stability on wind turbine performance in real condition. It is shown that the atmospheric stability calculated using the standard wind measurements from a conventional weather mast could be applied for every turbine in a medium size wind farm (33 wind turbines). This influence is very sensitive to the shape factor k of the wind speed distribution. The loss of AEP between neutral/stable conditions could be neglected while the loss of AEP between unstable/stable conditions is significant and depends on the average wind speed. In practice, it is possible to consider this influence during the wind resource assessment study while knowing the percentage of each atmospheric stability condition and the distribution of wind speed on the site.