Wind-farm layout optimisation using a hybrid Jensen–LES approach

Abstract. Given a wind farm with known dimensions and number of wind turbines, we try to find the optimum positioning of wind turbines that maximises wind-farm energy production. In practice, given that optimisation has to be performed for many wind directions, and taking into account the yearly wind distribution, such an optimisation is computationally only feasible using fast engineering wake models such as the Jensen model. These models are known to have accuracy issues, in particular since their representation of wake interaction is very simple. In the present work, we propose an optimisation approach that is based on a hybrid combination of large-eddy simulation (LES) and the Jensen model; in this approach, optimisation is mainly performed using the Jensen model, and LES is used at a few points only during optimisation for online tuning of the wake-expansion coefficient in the Jensen model, as well as for validation of the results. An optimisation case study is considered, in which the placement of 30 turbines in a 4 km by 3 km rectangular domain is optimised in a neutral atmospheric boundary layer. Optimisation for both a single wind direction and multiple wind directions is discussed.

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Wind-farm layout optimisation using a hybrid Jensen–LES approach

10.5194/wes-2016-15 ◽

2016 ◽

Cited By ~ 1

Author(s):

Vahid S. Bokharaie ◽

Pieter Bauweraerts ◽

Johan Meyers

Keyword(s):

Wind Turbines ◽

Energy Production ◽

Wind Farm ◽

Rectangular Domain ◽

Hybrid Combination ◽

Wake Interaction ◽

Large Eddy ◽

Wind Distribution ◽

Online Tuning

Abstract. Given a wind-farm with known dimensions and number of wind-turbines, we try to find the optimum positioning of wind-turbines that maximises wind-farm energy production. In practise, given that optimisation has to be performed for many wind directions and taking into account the yearly wind distribution, such an optimisation is computationally only feasible using fast engineering wake models such as, e.g., the Jensen model. These models are known to have accuracy issues, in particular since their representation of wake interaction is very simple. In the present work, we propose an optimisation approach that is based on a hybrid combination of Large-Eddy Simulations (LES) and the Jensen model, in which optimisation is mainly performed using the Jensen model, and LES is used at a few points only during optimisation for online tuning of the wake-expansion coefficient in the Jensen model, and for validation of the results. An optimisation case study is considered, in which the placement of 30 turbines in a 4 by 3 km rectangular domain is optimised in a neutral atmospheric boundary layer. Both optimisation for single wind direction, and multiple wind directions are discussed.

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Using field data–based large eddy simulation to understand role of atmospheric stability on energy production of wind turbines

Wind Engineering ◽

10.1177/0309524x18824540 ◽

2019 ◽

Vol 43 (6) ◽

pp. 625-638 ◽

Cited By ~ 1

Author(s):

Jordan Nielson ◽

Kiran Bhaganagar

Keyword(s):

Large Eddy Simulation ◽

Wind Turbines ◽

Surface Heat Flux ◽

Energy Production ◽

Surface Flux ◽

Surface Heat ◽

Net Energy ◽

Eddy Simulation ◽

Large Eddy

A novel and a robust high-fidelity numerical methodology has been developed to realistically estimate the net energy production of full-scale horizontal axis wind turbines in a convective atmospheric boundary layer, for both isolated and multiple wind turbine arrays by accounting for the wake effects between them. Large eddy simulation has been used to understand the role of atmospheric stability in net energy production (annual energy production) of full-scale horizontal axis wind turbines placed in the convective atmospheric boundary layer. The simulations are performed during the convective conditions corresponding to the National Renewable Energy Laboratory field campaign of July 2015. A mathematical framework was developed to incorporate the field-based measurements as boundary conditions for the large eddy simulation by averaging the surface flux over multiple diurnal cycles. The objective of the study is to quantify the role of surface flux in the calculation of energy production for an isolated, two and three wind turbine configuration. The study compares the mean value, +1 standard deviation, and −1 standard deviation from the measured surface flux to demonstrate the role of surface heat flux. The uniqueness of the study is that power deficits from large eddy simulation were used to determine wake losses and obtain a net energy production that accounts for the wake losses. The frequency of stability events, from field measurements, is input into the calculation of an ensemble energy production prediction with wake losses for different wind turbine arrays. The increased surface heat flux increases the atmospheric turbulence into the wind turbines. Higher turbulence results in faster wake recovery by a factor of two. The faster wake recovery rates result in lowering the power deficits from 46% to 28% for the two-turbine array. The difference in net energy production between the +1 and −1 standard deviation (with respect to surface heat flux) simulations was 10% for the two-turbine array and 8% for the three-turbine array. An ensemble net energy production by accounting for the wake losses indicated the overestimation of annual energy production from current practices could be corrected by accounting for variation of surface flux from the mean value.

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Research on the Power Capture and Wake Characteristics of a Wind Turbine Based on a Modified Actuator Line Model

Energies ◽

10.3390/en15010282 ◽

2022 ◽

Vol 15 (1) ◽

pp. 282

Author(s):

Feifei Xue ◽

Heping Duan ◽

Chang Xu ◽

Xingxing Han ◽

Yanqing Shangguan ◽

...

Keyword(s):

Wind Turbine ◽

Output Power ◽

Wind Turbines ◽

Wind Farm ◽

Three Dimensional ◽

Wind Farms ◽

Line Model ◽

Eddy Simulation ◽

Large Eddy ◽

Actuator Line Model

On a wind farm, the wake has an important impact on the performance of the wind turbines. For example, the wake of an upstream wind turbine affects the blade load and output power of the downstream wind turbine. In this paper, a modified actuator line model with blade tips, root loss, and an airfoil three-dimensional delayed stall was revised. This full-scale modified actuator line model with blades, nacelles, and towers, was combined with a Large Eddy Simulation, and then applied and validated based on an analysis of wind turbine wakes in wind farms. The modified actuator line model was verified using an experimental wind turbine. Subsequently, numerical simulations were conducted on two NREL 5 MW wind turbines with different staggered spacing to study the effect of the staggered spacing on the characteristics of wind turbines. The results show that the output power of the upstream turbine stabilized at 5.9 MW, and the output power of the downstream turbine increased. When the staggered spacing is R and 1.5R, both the power and thrust of the downstream turbine are severely reduced. However, the length of the peaks was significantly longer, which resulted in a long-term unstable power output. As the staggered spacing increased, the velocity in the central near wake of the downstream turbine also increased, and the recovery speed at the threshold of the wake slowed down. The modified actuator line model described herein can be used for the numerical simulation of wakes in wind farms.

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Numerical Simulation of Rotor-Tower Wake Interaction in Wind Farm

Volume 1D, Symposia: Transport Phenomena in Mixing; Turbulent Flows; Urban Fluid Mechanics; Fluid Dynamic Behavior of Complex Particles; Analysis of Elementary Processes in Dispersed Multiphase Flows; Multiphase Flow With Heat/Mass Transfer in Process Technology; Fluid Mechanics of Aircraft and Rocket Emissions and Their Environmental Impacts; High Performance CFD Computation; Performance of Multiphase Flow Systems; Wind Energy; Uncertainty Quantification in Flow Measurements and Simulations ◽

10.1115/fedsm2014-21953 ◽

2014 ◽

Author(s):

Xiangyu Gao ◽

Nina Zhou ◽

Jun Chen

Keyword(s):

Numerical Simulation ◽

Large Eddy Simulation ◽

Wind Farm ◽

Wind Farms ◽

Eddy Simulation ◽

Wake Interaction ◽

Large Eddy ◽

Wake Interactions ◽

Nrel Phase Vi ◽

Turbine Wake

This paper presents a numerical simulation of unsteady flow over wind turbine arrays to understand rotor-rotor and rotor-tower wake interaction in wind farms. The computations are carried out by incorporating Actuator Line method into a large eddy simulation. This methodology is validated by comparing the results to predictions of large eddy simulation using exact 3D blade geometries from a two-blade NREL Phase VI turbine. The method is then used to simulate the wake development in a two-turbine case. It is discovered that in the full wake setting the tower has a significant influence on the central part of the turbine wake. It is observed that the tower wake is twisted due to the rotation of the turbine wake. As a result, this tower wake is expected to have impact on the performance of downstream wind turbines, which cannot be overlooked. The present work also demonstrates the potential of combining AL method with LES to predict wake interactions in wind farms.

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Temperature and Wind Distribution Effects on Wind Energy Production in Adrar Region (Southern Algeria)

International Journal of Sustainable Development and Planning ◽

10.18280/ijsdp.160808 ◽

2021 ◽

Vol 16 (8) ◽

pp. 1473-1477

Author(s):

Miloud Benmedjahed ◽

Abdeldjalil Dahbi ◽

Abdelkader Hadidi ◽

Samir Mouhadjer

Keyword(s):

Wind Energy ◽

Wind Turbines ◽

Energy Production ◽

Wind Farm ◽

Electricity Consumption ◽

Electricity Production ◽

Effect Of Temperature ◽

Short Period ◽

Monthly Period ◽

Wind Distribution

The hottest transitions occur in the summer, as we notice during this period the peak of electricity consumption in Adrar, where the electricity network must use all kinds of energy, especially the wind energy produced by Cabertein wind farm. We evaluated the effect of temperature and wind distribution on the energy produced by one of Gamesa G52 wind turbines, and this was done by studying the wind distribution and determining the number of hours per year according to five cases. Finally, to estimate the monthly produced energy, we used a logical temperature equation, and then we determined the seasonal and annual energy. Low winds are the only reason why wind turbines are unable to produce electricity for a monthly period ranging from 152 An hour (May) to 274 hours (September), meaning that the seasonal production stop, for this reason, ranges between 590 hours (spring) and 779 hours (summer), with an average of 2736 hours per year, while temperatures did not constitute an obstacle to electricity production except. In three months for a short period of 2 hours (June and July) and 22 hours (August), affecting production in the summer season, with an estimated time of 26 hours.

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Computational Fluid Dynamics (CFD) Investigation of Wind Turbine Nacelle Separation Accident over Complex Terrain in Japan

10.20944/preprints201805.0290.v1 ◽

2018 ◽

Author(s):

Uchida Takanori

Keyword(s):

Wind Turbines ◽

Complex Terrain ◽

Wind Farm ◽

Turbulence Modeling ◽

Separated Flow ◽

Computational Prediction ◽

Scale Model ◽

Eddy Simulation ◽

Large Eddy ◽

Computational Fluid Dynamics Cfd

We have developed an unsteady and non-linear wind synopsis simulator called RIAM-COMPACT (Research Institute for Applied Mechanics, Kyushu University, COMputational Prediction of Airflow over Complex Terrain) in order to simulate the airflow on a microscale, i.e., a few tens of km or less. In RIAM-COMPACT, the large-eddy simulation (LES) has been adopted for turbulence modeling. LES is a technique in which the structures of relatively large eddies are directly simulated and smaller eddies are modeled using a sub-grid scale model. In the present study, we have conducted the numerical wind diagnoses for Taikoyama Wind Farm nacelle separation accident in Japan. The simulation results suggest that all six wind turbines at the Taikoyama Wind Farm are subject to significant influence from separated flow (terrain-induced turbulence) which is generated due to the topographic irregularities in the vicinity of the wind turbines. A proposal has been also made on reconstruction of the wind farm.

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Turbulence-Induced Anti-Stokes Flow and the Resulting Limitations of Large-Eddy Simulation

Journal of Physical Oceanography ◽

10.1175/jpo-d-17-0208.1 ◽

2018 ◽

Vol 48 (1) ◽

pp. 117-122 ◽

Cited By ~ 6

Author(s):

Brodie Pearson

Keyword(s):

Stokes Flow ◽

Energy Production ◽

Surface Wind ◽

Stokes Drift ◽

Near Surface ◽

Eddy Simulation ◽

Surface Wind Stress ◽

Planetary Rotation ◽

Large Eddy ◽

Anti Stokes

AbstractThis study shows that the presence of Stokes drift us in the turbulent upper ocean induces a near-surface Eulerian current that opposes the Stokes drift. This current is distinct from previously studied anti-Stokes currents because it does not rely on the presence of planetary rotation or mean lateral gradients. Instead, the anti-Stokes flow arises from an interaction between the Stokes drift and turbulence. The new anti-Stokes flow is antiparallel to us near the ocean surface, is parallel to us at depth, and integrates to zero over the depth of the boundary layer. The presence of Stokes drift in large-eddy simulations (LES) is shown to induce artificial energy production caused by a combination of the new anti-Stokes flow and LES numerics. As a result, care must be taken when designing and interpreting simulations of realistic wave forcing, particularly as rotation becomes weak and/or us becomes perpendicular to the surface wind stress. The mechanism of the artificial energy production is demonstrated for a generalized LES subgrid scheme.

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