Abstract
Wind turbine wake effects in wind farms not only reduce the wind farm power production but also influence the wind farm power dependency on wind direction. In this paper, the wake effects in wind farm layouts consisting of curved and straight wind turbine rows are studied using engineering wake models and a Reynolds-averaged Navier-Stokes model. These models predict a similar annual energy production for both wind farm layouts, but show stronger wake losses in the aligned wind directions for a rectangular wind farm layout, while the wake losses for a curved wind farm layout are more spread out over a larger wind direction sector. An energy system level simulation predicts that the enhanced spreading of wake losses over wind directions results in less hourly variability in energy generation on a Danish energy system level. Thus, our results show that a curved wind farm layout is more favorable compared to a wind farm layout with straight rows.
Highlights
The global cumulative offshore wind energy capacity has increased exponentially over the last decade and is expected to further increase in order to reduce the need of CO2 producing energy sources [1]
All results obtained with the engineering wake models and Reynolds-averaged Navier-Stokes (RANS) model are post processed with a Gaussian filter using a standard deviation of σ = 5◦ to represent the effect of wind direction uncertainty, as discussed by Gaumond et al [26]
On plant-level, for both the Horns Rev II wind farm and single wind turbine row, engineering wake models and RANS simulations predict that the power generation of the pseudo-straightened layouts are more dependent on wind direction compared to the actual curved layouts, while the difference in annual energy production (AEP) between the wind farm layouts is negligible
Summary
The global cumulative offshore wind energy capacity has increased exponentially over the last decade and is expected to further increase in order to reduce the need of CO2 producing energy sources [1]. The energy output of a wind farm mainly depends on the wind speed, but energy losses due to wake effects [3], which depend on wind speed, wind direction and wind farm layout, affect the energy output. These factors are contributing to a fluctuating energy supply to the electricity grid. The wake losses in wind turbine layouts with curved and straight rows are investigated. We show that the energy production of wind farm layouts with straight rows is more dependent on wind direction than the production of wind farms with curved layouts. We observe the effect of wind direction dependency on an energy system level
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