Steady

Lillgrund Direction

Submitted by Matthew Churchfield on May 4, 2015 - 3:54pm

Scope

This document outlines three separate components of this benchmark.  It is the hope that the participant will simulate all three components, but the participant is free to simulate any or all of the components.

This benchmark is open to participants of the Wakebench project using wake and, possibly, atmospheric boundary layer models. This is based on the actual operational Lillgrund wind farm in which there are multiple turbines interacting within an array.  The benchmark aims to test a wake/atmospheric model to reproduce the power production observed at Lillgrund when wind is from a southwesterly, southeasterly, and northwesterly sector. 

For the Southwest case, the sector is centered upon 222° aligned with rows A-H in which there is 4.3 rotor diameter (D) spacing.  For the Southeast case, the sector is centered upon 120° aligned with rows 1-8 in which there is a 3.3 D spacing.  For the Northwest case, the sector is centered upon the 300° direction aligned again with rows 1-8, with flow coming from the opposite direction of the Southeast case, with a 3.3 D spacing.

Lillgrund 360 Efficiency

Submitted by Matthew Churchfield on May 4, 2015 - 3:12pm

Scope

The benchmark is open to participants of the Wakebench project using wake and, possibly, atmospheric boundary layer models. This is a case based on the actual operational Lillgrund wind farm in which there are multiple turbines interacting within an array.  This benchmark aims to test a wake/atmospheric model to reproduce the wind plant efficiency observed at Lillgrund over the full wind rose.

Objectives

Demonstrate how wake models perform and capture the wake formation and merging process in the presence of atmospheric shear and turbulence within a large modern wind farm composed of modern multimegawatt turbines. 

Data Accessibility

Brief description about the accessibility of the data

Input data

The conditions for simulating the Lillgrund_360_Efficiency case are:

Lillgrund TI Spacing

Submitted by Matthew Churchfield on May 4, 2015 - 3:09pm

Scope

The benchmark is open to participants of the Wakebench project using wake and, possibly, atmospheric boundary layer models. This is a case based on the actual operational Lillgrund wind farm in which there are multiple turbines interacting within an array.  This benchmark aims to test a wake/atmospheric model to reproduce the maximum power deficit of the second turbine in a row as a function of spacing and turbulence intensity.

Objectives

Demonstrate how wake models perform and capture the wake formation and merging process in the presence of atmospheric shear and turbulence within a large modern wind farm composed of modern multimegawatt turbines. 

Data Accessibility

The benchmark is offered to participants of the IEA Task 31 Wakebench.

Input data

The conditions for simulating the LillgrundTISpacing case are:

Leipzig Neutral

Javier Sanz Rodrigo's picture
Submitted by Javier Sanz Rodrigo on May 4, 2015 - 3:04pm

Scope

The benchmark is open to participants of the Wakebench project using atmospheric boundary layer models. This is the first element of the building-block approach in this range, so it should be mandatory if you intend to participate with this model in other test cases down the line.

Objectives

Demonstrate how ABL models reproduce the characteristic Ekman spiral in neutral conditions represented by prescribed Leipzig profile conditions.

Data Accessibility

The benchmark is offered to participants of the IEA Task 31 Wakebench. In the future it will be open for public access.

Input data

The conditions for simulating the Leipzig wind profile in neutral conditions are:

  • Geostrophic wind: Ug = 17.5 m/s, Vg=0
  • Coriolis parameter: fc = 1.13e-4 s-1
  • Roughness length: z0 = 0.3 m
  • Obukhov length: L = ∞
  • Use dry air with a density ρ = 1.225 kg/m3 and dynamic viscosity μ = 1.73e-5 kg/ms

Validation data

The validation data consists on vertical profiles of velocity components and eddy viscosity as estimated by Lettau (1950).

Model runs

A 3 km high domain should be used, sufficient to fit the boundary layer height with some margin.

Leipzig Stratified

Javier Sanz Rodrigo's picture
Submitted by Javier Sanz Rodrigo on May 4, 2015 - 3:03pm

Scope

The benchmark is open to participants of the Wakebench project using atmospheric boundary layer models that include thermal stratification.

Objectives

Parameterize the ABL to obtain the best fit to the Leipzig profile and report on the resulting boundary layer characteristics.

Data Accessibility

The benchmark is offered to participants of the IEA Task 31 Wakebench. In the future it will be open for public access.

Input data

The conditions for simulating the Leipzig wind profile in stable conditions are:

  • Inlet profiles of velocity components and turbulent viscosity
  • Coriolis parameter: fc =1.3e-4 s-1
  • Use dry air with a density ρ = 1.225 kg/m3 and dynamic viscosity μ = 1.73e-5 kg/ms

Validation data

The validation profiles are the same as the inlet profiles, as obtained from Lettau (1950). The participant is asked to provide the best fit of the ABL model to these input data profiles.

Model runs

A 3 km high domain should be used, sufficient to fit the boundary layer height with some margin.

Horns Rev Neutral

Submitted by Kurt Schaldemos... on May 4, 2015 - 2:40pm

Scope

The benchmark is open to participants of both Wakebench and EERA-DTOC for wake model validation on wind farms with regular layout under neutral atmospheric conditions.

Objectives

Determine the power deficit along a single row of 10 turbines, with an internal spacing of 7D, inside a wind farm of regular layout. Evaluate the sensitivity of the model performance to the wind direction sector size.

Data Accessibility

The benchmark is offered to participants of the IEA Task 31 Wakebench and EU project EERA-DTOC Work Package 1.

Input data

The conditions for simulating the wind farm flow are:

Horns Rev Stratified

Submitted by Kurt Schaldemos... on May 4, 2015 - 2:38pm

Scope

The benchmark is open to participants of both Wakebench and EERA-DTOC for wake model validation on wind farms with regular layout under neutral atmospheric conditions.

Objectives

Determine the power deficit along a single row of 10 turbines, with an internal spacing of 7D, inside a wind farm of regular layout. Evaluate the sensitivity of the model performance for three atmospheric stratifications, which can be categorized as stable, neutral or unstable.

Data Accessibility

The benchmark is offered to participants of the IEA Task 31 Wakebench and EU project EERA-DTOC Work Package 1.

Input data

The conditions for simulating the wind farm flow are:

Horns Rev Turbulence

Submitted by Kurt Schaldemos... on May 4, 2015 - 2:37pm

Scope

The benchmark is open to participants of both Wakebench and EERA-DTOC for wake model validation on wind farms with regular layout under neutral atmospheric conditions.

Objectives

Evaluate park models on a wind farm with well defined boundary conditions to determine the power deficit. The power deficit is determined between two nearby turbines. The power deficit is determined for 8 m/s hub height wind speed as function of turbulence intensity.

Data Accessibility

The benchmark is offered to participants of the IEA Task 31 Wakebench and EU project EERA-DTOC Work Package 1.

Input data

The conditions for simulating the wind farm flow are:

  • Wind farm layout and coordinates of the wind turbine positions (1);
  • V80-2MW turbine specifications (1);
  • Roughness length: z0 = 0.0001 m;
  • Inflow mean velocity at hub height (70 m): 8 m/s.

Validation data

a) The power deficit has been extracted from the SCADA dataset and averaged for wt17 and wt07 with reference to the operational conditions of wind turbine wt07.

Horns Rev Spacing

Submitted by Kurt Schaldemos... on May 4, 2015 - 2:35pm

Scope

The benchmark is open to participants of both Wakebench and EERA-DTOC for wake model validation on wind farms with regular layout under neutral atmospheric conditions.

Objectives

Determine the power deficit along single rows consisting of 6 or 10 turbines, with an varying internal spacing, inside a wind farm of regular layout. Evaluate the sensitivity of the model performance to the spacing.

Data Accessibility

The benchmark is offered to participants of the IEA Task 31 Wakebench and EU project EERA-DTOC Work Package 1.

Input data

The conditions for simulating the wind farm flow are:

Furry Hill Neutral

Javier Sanz Rodrigo's picture
Submitted by Javier Sanz Rodrigo on May 4, 2015 - 2:33pm

Scope

The benchmark is open to participants of the Wakebench project using canopy models. The benchmark will evaluate the ability of the models at reproducing the interaction of canopy and hill flows in idealized conditions.

Objectives

Demonstrate the performance of the models at reproducing mean flow and turbulent quantities on a hill-induced heterogeneous canopy. Test model fine-tuning strategies in a controlled environment when boundary conditions are well defined.

Data Accessibility

The benchmark is offered to participants of the IEA Task 31 Wakebench who agree with the terms and conditions described below.

Input data

The conditions for simulating the Furry Hill experiment in neutral conditions are:

  • Inlet profile: measurements at X = -2.125 m (X/L = -5.06)
  • Hill profile: Zh(X)=h/(1+(X/L)2), with X = 0 at the crest of the ridge, truncated at X = ±925 mm where it smoothly meets the flat floor. Ridge height h = 150 mm, half-length L = 420 mm.
  • Canopy height: hc = 0.047 m
  • Canopy drag coefficient: Cd = 0.68
  • Canopy-area-density: A = 0.1 m-1
  • Obukhov length: L0 = ∞
  • Use dry air with a density ρ = 1.225 kg/m3 and dynamic viscosity μ = 1.73e-5 kg/ms