The performance of arrays of wind turbines

Abstract To assess the amount of power available in the wind, interactions between wind turbines in an array, or cluster, have been studied using a number of experimental techniques, and methods of mathematical analysis. These studies have included wake measurements behind wind turbine rotors and wind tunnel tests of model clusters, together with analyses using wake mixing and boundary-layer theories. The results from these studies are reviewed and compared and it is shown that there is reasonable agreement between the estimates for the power loss due to interactive effects in a cluster generating 1000 MW (about 25% is lost, if the rotors are spaced 10 diameters apart). Estimates of the output from larger arrays show some variation and there are conflicting views on the effects of certain parameters — such as rotor height. Other topics requiring further study — such as the influence of machine design — are also identified and discussed.