Quantifying the Impact of Wind Turbine Wakes on Power Output at Offshore Wind Farms

TLDR

Offshore wind farm design urgently requires improved tools, yet wake modeling remains highly uncertain. This study seeks to enhance wake modeling to produce more accurate power output predictions for large offshore wind farms. The authors analyze detailed power‑loss data from Nysted and Horns Rev and simulate ensemble averages with various wind‑farm and CFD models to compare against observed wake losses. They found that turbine spacing differences were not distinguishable in wake‑related power losses due to high variability, but models captured wake width and power decline, with better accuracy at higher wind speeds and along the row flow.

Abstract

Abstract There is an urgent need to develop and optimize tools for designing large wind farm arrays for deployment offshore. This research is focused on improving the understanding of, and modeling of, wind turbine wakes in order to make more accurate power output predictions for large offshore wind farms. Detailed data ensembles of power losses due to wakes at the large wind farms at Nysted and Horns Rev are presented and analyzed. Differences in turbine spacing (10.5 versus 7 rotor diameters) are not differentiable in wake-related power losses from the two wind farms. This is partly due to the high variability in the data despite careful data screening. A number of ensemble averages are simulated with a range of wind farm and computational fluid dynamics models and compared to observed wake losses. All models were able to capture wake width to some degree, and some models also captured the decrease of power output moving through the wind farm. Root-mean-square errors indicate a generally better model performance for higher wind speeds (10 rather than 6 m s−1) and for direct down the row flow than for oblique angles. Despite this progress, wake modeling of large wind farms is still subject to an unacceptably high degree of uncertainty.