Cluster wakes impact on a far distant offshore wind farm's power

Schneemann, Jörge; Rott, Andreas; Dörenkämper, Martin; Steinfeld, Gerald; Kühn, Martin

doi:10.5194/wes-2019-39

Cited by 10 publications

(26 citation statements)

References 32 publications

(51 reference statements)

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“…In the wind directions we chose for the analysis of global blockage, no distinct wind speed gradients are present in the inflow. Schneemann et al (2020) did not find signatures of the wakes of single wind turbines in the inflow of GT I. Nygaard and Newcombe (2018) showed dual-Doppler radar measurements of a wind farm wake with the signatures of single wind turbines disappearing less than 10 km behind the farm.…”

Section: Global Blockage Dependent On Atmospheric and Operational Conditionsmentioning

confidence: 90%

“…2.4. Schneemann et al (2020) give further information about the measurements, and Schneemann et al (2019) provide some exemplary lidar scans from this campaign.…”

Section: Lidar Measurementsmentioning

confidence: 99%

“…Information regarding stability further allows us to analyse the effect of atmospheric conditions on global blockage. We used a similar methodology to derive atmospheric stratification as in Theuer et al (2020b) and Schneemann et al (2020), which is described here for completeness. To characterize atmospheric stability (Emeis, 2018), we used local measurements as well as reanalysis data.…”

Section: Atmospheric-stability Characterization and Meteorological Measurementsmentioning

confidence: 99%

“…Influences of cluster wakes. Schneemann et al (2020) show the existence of cluster wakes in the inflow of GT I using data from the same measurement campaign as used here.…”

Section: Global Blockage Dependent On Atmospheric and Operational Conditionsmentioning

confidence: 99%

“…Commercial scanning lidar systems allow for measuring the line-of-sight (LOS) component of the wind vector on several hundred positions along the emitted laser beam and for orientating the beam in any direction. Scanning lidars have enabled many new insights into different fields of wind energy research, like wind turbine wakes (Käsler et al, 2010;Trabucchi et al, 2014), wind farm cluster wakes (Schneemann et al, 2020), resource assessment in complex terrain (Menke et al, 2020) and minutescale wind power forecasts (Theuer et al, 2020b).…”

Section: Introductionmentioning

confidence: 99%

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Offshore wind farm global blockage measured with scanning lidar

et al. 2021

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Abstract. The objective of this paper was the experimental investigation of the accumulated induction effect of a large offshore wind farm as a whole, i.e. the global-blockage effect, in relation to atmospheric-stability estimates and wind farm operational states. We measured the inflow of a 400 MW offshore wind farm in the German North Sea with a scanning long-range Doppler wind lidar. A methodology to reduce the statistical variability of different lidar scans at comparable measurement conditions was introduced, and an extensive uncertainty assessment of the averaged wind fields was performed to be able to identify the global-blockage effect, which is small compared to e.g. wind turbine wake effects and ambient variations in the inflow. Our results showed a 4 % decrease in wind speed (accuracy range of 2 % to 6 %) at transition piece height (24.6 m) upwind of the wind farm with the turbines operating at high thrust coefficients above 0.8 in a stably stratified atmosphere, which we interpreted as global blockage. In contrast, at unstable stratification and similar operating conditions and for situations with low thrust coefficients (i.e. approx. 0 for not operating turbines and ≤ 0.3 for turbines operating far above rated wind speed) we identified no wind speed deficit. We discussed the significance of our measurements and possible sources of error in long-range scanning lidar campaigns and give recommendations on how to measure small flow effects like global blockage with scanning Doppler lidar. In conclusion, we provide strong evidence for the existence of global blockage in large offshore wind farms in stable stratification and the turbines operating at a high thrust coefficient by planar lidar wind field measurements. We further conclude that global blockage is dependent on atmospheric stratification.

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Section: Global Blockage Dependent On Atmospheric and Operational Conditionsmentioning

confidence: 90%

“…2.4. Schneemann et al (2020) give further information about the measurements, and Schneemann et al (2019) provide some exemplary lidar scans from this campaign.…”

Section: Lidar Measurementsmentioning

confidence: 99%

Section: Atmospheric-stability Characterization and Meteorological Measurementsmentioning

confidence: 99%

“…Influences of cluster wakes. Schneemann et al (2020) show the existence of cluster wakes in the inflow of GT I using data from the same measurement campaign as used here.…”

Section: Global Blockage Dependent On Atmospheric and Operational Conditionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Offshore wind farm global blockage measured with scanning lidar

et al. 2021

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Wind farm flow control oriented to electricity markets and grid integration: Initial perspective analysis

et al. 2021

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Wind farm control (WFC) allows coordinated operation of the wind turbines within a wind power plant (WPP). However, its development has traditionally been split into the distinct disciplines of power plant control and farm flow control. As variable renewable energies, in particular wind energy, increase their penetration into the power system, grid code requirements become stricter for WPPs and electricity markets necessarily evolve. In such a context, crossfertilization between the two categories of WFC, targeting an integrated approach where applicable, becomes a priority. An initial overview on how to further align wind farm flow control (WFFC) to grid and electricity markets participation is provided, including an analysis of capabilities and prospects. In addition, greater detail is given about an open‐access dataset serving as market showcases for value demonstration of price‐driven operation of WPPs by means of WFFC.

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Impact of wind farm wakes on flow structures in and around downstream wind farms

Stieren

Stevens

2022

Flow

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We performed large-eddy simulations in a neutral atmospheric boundary layer to study the interaction between two identical wind farms with 72 turbines each. We demonstrate that the wind farm wake created by the upstream farm affects the entire flow in and around the downstream farm. The vertical entrainment fluxes above the downstream wind farm are strengthened, resulting in a faster wind farm wake recovery behind the downstream farm. These findings illustrate that interaction between extended wind farms affects flow structures beyond the wind farm scale. Furthermore, we demonstrate that wind farm wakes can reduce the power production of turbines throughout the downstream wind farms. We additionally observe that a staggered wind farm extracts more energy from the flow and thus creates a stronger wind farm wake than an aligned wind farm.

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Cluster wakes impact on a far distant offshore wind farm's power

Cited by 10 publications

References 32 publications

Offshore wind farm global blockage measured with scanning lidar

Offshore wind farm global blockage measured with scanning lidar

Wind farm flow control oriented to electricity markets and grid integration: Initial perspective analysis

Impact of wind farm wakes on flow structures in and around downstream wind farms

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