C.: ”Verification of an efficiency model for very large wind turbine clusters

In the paper an analytical model for very large arrays of wind turbines is verified against measurements. Contrary to existing engineering tools the model accounts for the wind farm’s interaction with the atmospheric boundary layer. As it is often the need for offshore wind farms, the model handles a regular array-geometry with straight rows of wind turbines and equidistant spacing between units in each row and equidistant spacing between rows. The case with the flow direction being parallel to rows in a rectangular geometry is considered by defining three flow regimes. In this paper the case of the direct wake with flow within ±2.5 ° of the direction of the rows is considered. Data used here are from the measurements presently being conducted at the Danish demonstration offshore wind farm at Horns Rev. The data encompass power from the wind turbine units and other relevant parameters, and flow characteristics measured by means of a number of meteorological masts situated in the vicinity of the wind farms. Results from the smaller offshore wind farm at Middelgrunden are used to provide a second case study. There are no meteorological measurements to provide the freestream but the power output from each turbine in the wind farm is available. The model is not in a “closed form ” and therefore experimental information is needed to determine model parameters. The geometries of the two wind farms are different, thus offering a range of flow conditions, which is useful in terms of model verification. Therefore, results from measurements will serve both model calibration and verification of the principles applied