Posters

Abstract

Wind farm blockage effect has been a topic of interest in the wind industry over the last few years as a potential explanation for continued overestimate of energy production in pre-construction wind resource assessments. The physical explanation of this effect is still being researched, but there is a general agreement on relating the blockage effect to the two-way interaction that occurs between a large operating wind farm and the atmospheric boundary layer. Modelling of the effect indicates an upstream wind speed deficit, compared to freestream, in post-commercial operations of large wind farms. This can lead to lower energy production in comparison to expected production if the freestream were only perturbed by the usual per-turbine induction effect and wake-only wind turbine interaction. Several numerical methods have been developed recently to account for the blockage loss, but there is still a lack of experimental data to quantify and better understand this effect as well as validate the different theoretical models. To help address this data gap, Enel Green Power conducted measurements of the blockage effect at three large onshore wind farms, including installation of meteorological towers at locations selected specifically to measure any blockage upwind of the projects, speedup around the sides, and as nearby unaffected control locations. This work presents the results of the measurement campaigns, including quantification of the observed blockage effect and discussion of the uncertainty on the measurements.