OUTLINE

An Experimental Study on the Effects of Wake An Experimental Study on the Effects of Wake

Interference on the Performance of Wind Turbines Interference on the Performance of Wind Turbines

over Flat and Complex Terrainsover Flat and Complex TerrainsAdvanced Flow Diagnostics and Experimental Aerodynamics LaboratoryAdvanced Flow Diagnostics and Experimental Aerodynamics Laboratory

Department of Aerospace EngineeringDepartment of Aerospace Engineering

Ahmet Ozbay, Wei Tian and Hui HuAhmet Ozbay, Wei Tian and Hui Hu

Iowa State UniversityIowa State University2242 Howe Hall, Ames, Iowa 50011-22712242 Howe Hall, Ames, Iowa 50011-2271

Email: [email protected]: [email protected]

OUTLINEOUTLINE

1.1. Motivation/ObjectivesMotivation/Objectives

2.2. IntroductionIntroduction

3.3. Experimental set-up and procedureExperimental set-up and procedure

4.4. Investigation of wake interference effects Investigation of wake interference effects

A.A. Wake interference of wind turbines with different spacingWake interference of wind turbines with different spacing

B.B. Wake interference within an array of turbines in a lineWake interference within an array of turbines in a line

C.C. Multiple wake interactions in wind farms with different layoutsMultiple wake interactions in wind farms with different layouts

D.D. Upstream turbine operating(yaw) conditionsUpstream turbine operating(yaw) conditions

E.E. Terrain (2D-Ridge) effects on the wake interferences among multiple wind Terrain (2D-Ridge) effects on the wake interferences among multiple wind

turbinesturbines5.5. SummarySummary

Velocity deficit: Velocity deficit:

Enhancement of turbulence intensity: Enhancement of turbulence intensity:

The power output could lose up to 40% when the wind The power output could lose up to 40% when the wind turbine placed in the wake.turbine placed in the wake.

The velocity deficit is linked to the amount of power The velocity deficit is linked to the amount of power can be extracted from the flow.can be extracted from the flow.

Enhanced turbulence intensity in the wake is Enhanced turbulence intensity in the wake is associated directly with the fatigue loads and failure of associated directly with the fatigue loads and failure of the wind turbine components.the wind turbine components.

The most important aerodynamic aspects in the design of wind farms:The most important aerodynamic aspects in the design of wind farms:

Objectives of the Present StudyObjectives of the Present Study

(1) Investigating the effects (1) Investigating the effects of the array spacing and wind turbines layout of the array spacing and wind turbines layout on the wake interference and on the wake interference and performance of multiple wind turbines sited in a wind farm for higher total power yield and better durability.performance of multiple wind turbines sited in a wind farm for higher total power yield and better durability.(2) Investigating the (2) Investigating the effects of topography effects of topography (complex terrains -2D Ridge) on the wind turbine performance as well (complex terrains -2D Ridge) on the wind turbine performance as well as on the wake interactionas on the wake interaction(3) Investigating the effects of (3) Investigating the effects of upstream turbine operating (yaw, pitch) conditions upstream turbine operating (yaw, pitch) conditions on the efficiency of wind farmon the efficiency of wind farm

((Barthelmie et al., 2007)Barthelmie et al., 2007)

How to reduce the wake induced effects over flat and complex terrains?How to reduce the wake induced effects over flat and complex terrains?

Offshore wind farms:Offshore wind farms: Wind turbines sitting on flat ocean surfaceWind turbines sitting on flat ocean surface Near neutral atmospheric boundary layer windsNear neutral atmospheric boundary layer winds High wind speed with relatively High wind speed with relatively low ambient low ambient

turbulence levelturbulence level Suffers from ‘Suffers from ‘deep array effectdeep array effect’’

Onshore wind farms:Onshore wind farms: Wind turbines sitting over complex terrains.Wind turbines sitting over complex terrains. Atmospheric stability is rarely close to near-Atmospheric stability is rarely close to near-

neutral (highly convective – unstable during the neutral (highly convective – unstable during the day time and highly stable nocturnal conditions day time and highly stable nocturnal conditions with high shear at night time) with high shear at night time)

Much higher ambient turbulence levelMuch higher ambient turbulence level

(4) (4) Different characteristics of atmospheric boundary Different characteristics of atmospheric boundary layer winds layer winds were simulated to compare the performances were simulated to compare the performances of wind turbines sited in onshore and offshore wind farms. of wind turbines sited in onshore and offshore wind farms.

Objectives of the Present StudyObjectives of the Present Study

Comparison of onshore and offshore winds:Comparison of onshore and offshore winds:

LOG-WIND PROFILELOG-WIND PROFILE

POWER LAW PROFILEPOWER LAW PROFILE

INTRODUCTION – BOUNDARY LAYERINTRODUCTION – BOUNDARY LAYER

INTRODUCTION – WIND POWERINTRODUCTION – WIND POWER

POWER AVAILABLE IN THE WINDPOWER AVAILABLE IN THE WIND

WIND POWER DENSITY (WPD)(watts/mWIND POWER DENSITY (WPD)(watts/m22) is used to classify the winds) is used to classify the winds

Wind speedWind speed plays a crucial role in the wind power plays a crucial role in the wind power

10% increase in the wind speed leads to 33% 10% increase in the wind speed leads to 33% increase in the wind power densityincrease in the wind power density

Wind resource assessment Wind resource assessment is important for wind is important for wind turbine sitingturbine siting

INTRODUCTION – WIND RESOURCE ASSESSMENTINTRODUCTION – WIND RESOURCE ASSESSMENT

WIND MEASUREMENT TOOLSWIND MEASUREMENT TOOLS

•METEOROLOGICAL TOWERSMETEOROLOGICAL TOWERS

•ANEMOMETERS ( WIND SPEED)ANEMOMETERS ( WIND SPEED)

•WIND VANES ( WIND DIRECTION)WIND VANES ( WIND DIRECTION)

•SENSORS (TEMPERATURE, PRESSURE)SENSORS (TEMPERATURE, PRESSURE)

Weibull /Rayleigh probability functionWeibull /Rayleigh probability function

•Using probability density function over a wide range of wind speed Using probability density function over a wide range of wind speed to estimate the mean power from a turbine to estimate the mean power from a turbine

INTRODUCTION – WIND RESOURCE ASSESSMENT (2)INTRODUCTION – WIND RESOURCE ASSESSMENT (2)

Weibull /Rayleigh probability functionWeibull /Rayleigh probability function

Shape factor , k , shape of the curve Shape factor , k , shape of the curve depending on the standard deviation of depending on the standard deviation of the wind speed (the wind speed (σσuu) )

As k increases, mean velocity tends to As k increases, mean velocity tends to increase and wind speed variations (increase and wind speed variations (σσuu) )

fall downfall down

http://www.wind-power-program.com/wind_statistics.htm

INTRODUCTION – WIND TURBINE POWERINTRODUCTION – WIND TURBINE POWER

Limitations for wind turbine powerLimitations for wind turbine power

Betz limit – theoretical limit (CBetz limit – theoretical limit (Cpp=0.59)=0.59)

Cut in and cut out speedsCut in and cut out speeds

Power losses (wake, environmental, electrical, etc.)Power losses (wake, environmental, electrical, etc.)Optimum rangeOptimum range

(0.2 - 0.35)(0.2 - 0.35)

INTRODUCTION – WIND ENERGY IN U.S. INTRODUCTION – WIND ENERGY IN U.S.

• One of the One of the fastestfastest growth in terms of electric resource capacity, in GW, every year since 2005 growth in terms of electric resource capacity, in GW, every year since 2005

• US policy suggest that wind energy will continue to play US policy suggest that wind energy will continue to play dominant roledominant role in needs of in needs of new electric resources new electric resources in the world, US, Midwest, & Iowain the world, US, Midwest, & Iowa

• Wind turbine technology is in its infancy – needs to Wind turbine technology is in its infancy – needs to developdevelop along multiple dimensions over the next 40 along multiple dimensions over the next 40 yearsyears

• According to Department of Energy (DOE) recent report, US wind power can reach According to Department of Energy (DOE) recent report, US wind power can reach 300GW by 2030300GW by 2030, , with with on-shore (land-based) on-shore (land-based) wind capacity being a major contributorwind capacity being a major contributor

• Other predictions suggest as much as 600 GW by 2035Other predictions suggest as much as 600 GW by 2035

• A target of A target of 20% of US electricity 20% of US electricity from wind energy by 2030 has been set from wind energy by 2030 has been set up by the U.S. Department of Energy (DOE).up by the U.S. Department of Energy (DOE).

• Iowa is Iowa is secondsecond in the nation in installed wind energy capacity and it has in the nation in installed wind energy capacity and it has the the highest highest density of wind power generation capacity with density of wind power generation capacity with 29.9 kW/km29.9 kW/km22

• According to the Energy Information Administration (EIA), Iowa has According to the Energy Information Administration (EIA), Iowa has reached the milestone of 20% of the state’s electricity, supplying the reached the milestone of 20% of the state’s electricity, supplying the state with a full one fifth of its energy needs.state with a full one fifth of its energy needs.

Top Wind Energy Production States:Top Wind Energy Production States:•Texas: Texas: 10,377 MW10,377 MW•Iowa: Iowa: 4,322 MW4,322 MW•California:California: 3,927 MW3,927 MW•Illinois: Illinois: 2,743 MW2,743 MW•Minnesota:Minnesota: 2,733 MW2,733 MW•Washington: Washington: 2,573 MW2,573 MW•Oregon:Oregon: 2,513 MW2,513 MW

(The data as of Feb 28, 2012)(The data as of Feb 28, 2012)

INTRODUCTION – WIND ENERGY IN U.S. INTRODUCTION – WIND ENERGY IN U.S.

EXPERIMENTAL SET-UP AND PROCEDUREEXPERIMENTAL SET-UP AND PROCEDURE

ParameterParameterRR

(mm)(mm)H H

(mm)(mm)d d polepole

(mm)(mm)

d d nacellenacelle

(mm)(mm)

(deg.)(deg.)

aa(mm)(mm)

a1a1(mm)(mm)

a2a2(mm)(mm)

DimensionDimension 127127 225225 1818 1818 55oo 7878 1515 5050

1:350 1:350 scaled mscaled modelodel to simulate to simulate a 2MW wind turbine with 90m a 2MW wind turbine with 90m

rotor bladesrotor blades

Measured parameters:Measured parameters:• Dynamic wind loadsDynamic wind loads• Power output and rotational frequency Power output and rotational frequency

of wind turbine modelsof wind turbine models• Detailed flow field (mean velocity and Detailed flow field (mean velocity and

turbulence) measurements with cobra turbulence) measurements with cobra probeprobe

JR3 Force/Moment TransducerJR3 Force/Moment Transducer

Cobra probeCobra probe

Optical tachometerOptical tachometer

EXPERIMENTAL SET-UP AND PROCEDUREEXPERIMENTAL SET-UP AND PROCEDURE

127 mm

ERS-100 prototype of wind turbine blade developed by TPI

Simulation of Incoming Flow with Different Simulation of Incoming Flow with Different Turbulence LevelsTurbulence Levels

High turbulence intensity caseHigh turbulence intensity case (18% at hub height)(18% at hub height)

Low turbulence intensity caseLow turbulence intensity case (10% at hub height)(10% at hub height)

0

0.5

1.0

1.5

2.0

2.5

3.0

0.3 0.6 0.9 1.2

Power law (=0.15)

Experimental data

U(z)/Uhub

z/H

0

0.5

1.0

1.5

2.0

2.5

3.0

0 5 10 15 20 25

Turbulence intesity (%)

Z/H

• Wind speed profile of in Wind speed profile of in atmospheric boundary layer atmospheric boundary layer (ABL): (ABL):

Terrain Terrain CategoryCategory

Terrain descriptionTerrain description Gradient Gradient height, Zheight, Z

GG

(m)(m)

Roughness Roughness length, Zlength, Z

OO (m) (m)Wind Speed Wind Speed exponent, exponent,

11 Open sea, ice, tundra desertOpen sea, ice, tundra desert 250250 0.0010.001 0.110.11

22 Open country with low scrub Open country with low scrub or scattered treesor scattered trees

300300 0.030.03 0.150.15

33 Suburban area, small towns, Suburban area, small towns, well wooded areas well wooded areas

400400 0.30.3 0.250.25

44 Tall buildings, city centers, Tall buildings, city centers, well developed industrial well developed industrial areas areas

500500 3.03.0 0.360.36

GZ Z

ZUzU

G)(

0

0.5

1.0

1.5

2.0

2.5

3.0

0.3 0.6 0.9 1.2

Power law (=0.11)Experimental data

U(z)/Uhub

z/H

0

0.5

1.0

1.5

2.0

2.5

3.0

0 5 10 15 20 25

Turbulence intesity (%)

Z/H

Offshore wind farmOffshore wind farm =0.11=0.11

Onshore wind farmOnshore wind farm =0.15=0.15

POWER LAW POWER LAW PROFILEPROFILE


Open Open Terrain Terrain

CategoryCategory

Terrain Terrain descriptiondescription

Wind Speed Wind Speed exponent, exponent,

Mean wind Mean wind speed at the hub speed at the hub

height, Uheight, Umm

Standard Standard deviation at the deviation at the hub height wind hub height wind

speed, speed, σσ

Variance at the Variance at the hub height wind hub height wind

speed, speed, σσ22

IuuIuuTurbulence Turbulence

Intensity (%)Intensity (%)((σσ/U/Umm))

11 Open sea, ice, Open sea, ice, tundra deserttundra desert

0.110.11 5.35 m/s5.35 m/s 0.560.56 0.320.32 1010

22 Open country Open country with low scrub with low scrub or scattered treesor scattered trees

0.150.15 4.86 m/s4.86 m/s 0.880.88 0.780.78 1818




Weibull dimensionless shape factor (k) – breadth of the wind speed distributionWeibull dimensionless shape factor (k) – breadth of the wind speed distribution

The variation of the shape parameter with the incoming flow turbulence (The variation of the shape parameter with the incoming flow turbulence (σσ/U/Umm))

• As the incoming flow turbulence level decreases, the shape of the distribution tends As the incoming flow turbulence level decreases, the shape of the distribution tends to be tight – less variation in the wind speed (offshore)to be tight – less variation in the wind speed (offshore)

Wind speed distribution at the hub heightWind speed distribution at the hub height

Investigation of wake interference effects – AInvestigation of wake interference effects – AEffect of spacingEffect of spacing

Investigation of wake interference effects – AInvestigation of wake interference effects – AWake effects – PIV resultsWake effects – PIV results

Ensemble averaged (free-run)PIV resultsEnsemble averaged (free-run)PIV results

Phase locked PIV resultsPhase locked PIV results

Investigation of wake interference effects – AInvestigation of wake interference effects – AWake effects – PIV resultsWake effects – PIV results

Low turbulenceLow turbulenceHigh turbulenceHigh turbulence

The evolution of the wake vortex structure (phase-locked measurements)The evolution of the wake vortex structure (phase-locked measurements)

Power spectrum of the velocity fluctuations (u’) at the top-tip height (x/D=0.5)Power spectrum of the velocity fluctuations (u’) at the top-tip height (x/D=0.5)

Investigation of wake interference effects – BInvestigation of wake interference effects – B5 Turbines in a line5 Turbines in a line

6D6D 6D6D 6D6D 6D6D



pos 1pos 1 pos 2pos 2 pos 3pos 3 pos 4pos 4 pos 5pos 5

((Barthelmie et al., 2007)Barthelmie et al., 2007)

Investigation of wake interference effects – CInvestigation of wake interference effects – CMultiple wake interactions in wind farms with Multiple wake interactions in wind farms with

different layoutsdifferent layouts

(a) aligned wind farm with stream-wise spacing 3D (b) staggered wind farm with stream-wise spacing 3D

(c) aligned wind farm with stream-wise spacing 6D











Normalized power output(P/Palone )

Alone Aligned 3D-spacing Staggered 3D-spacing Aligned 6D-spacing

Low turbulence inflow 1.00 0.42 0.73 0.71

High turbulence inflow 1.00 0.57 0.85 0.78



Wind turbine position Alone Aligned 3D-spacing Staggered 3D-spacing Aligned 6D-spacing

Low Turbulence

Inflow

Thrust Coefficient CT

0.405 0.233 0.321 0.320

Bending moment

Coefficient CMy

0.467 0.255 0.364 0.356

High Turbulence

Inflow

Thrust Coefficient CT

0.404 0.312 0.388 0.382

Bending moment

Coefficient CMy

0.469 0.348 0.433 0.427





Aligned 3D-spacing Aligned 6D-spacingStaggered 3D-spacing

0.222

Standard Deviation of Thrust Force

0.145 0.145





Aligned 3D-spacing Aligned 6D-spacingStaggered 3D-spacing

0.277

Standard Deviation of Thrust Force

0.201 0.190



CP total : The total power output of wind farm

CP alone : Power output of single wind turbine under incoming flow

n : The number of wind turbine in the wind farm

Wind farm efficiency :


different layoutsdifferent layouts• In staggered wind farm, the velocity deficit and

added turbulence is much lower compared with the aligned wind farm.

• Staggered wind farm is much more efficient than the aligned wind farm with similar stream-wise and span-wise turbine spacing.

• The turbulence level of atmospheric boundary layer wind is effective on the wind farm efficiency.

• The improvement in the wind farm efficiency due to the incoming flow turbulence is more pronounced in the staggered wind farm.

3D Aligned wind farm

3D Staggered wind farm

Investigation of wake interference effects – DInvestigation of wake interference effects – DUpstream Turbine operating (yaw) conditionsUpstream Turbine operating (yaw) conditions

Two turbines in tandem arrangement with 2D spacing

Upstream turbine is installed on a turn table and yawed up to 50˚ with an increment of 10˚

Test cases: Flow measurements in the wake of the

upstream turbine with yaw angle from 0˚ to 50˚

The power output and dynamics forces for both upstream and downstream turbine

Flow field measurements in the near wake of the downstream turbine with the yaw angle of upstream turbine changing from 0˚ to 50˚

2D

U∞

Experimental set-up for wind Experimental set-up for wind tunneltunnel testing testing


Previous studies on upstream turbine operating (yaw) conditionsPrevious studies on upstream turbine operating (yaw) conditions

Effect of upstream turbine yaw angle on the Effect of upstream turbine yaw angle on the downstream turbine performancedownstream turbine performance

Effect of yaw angle on the performance of Effect of yaw angle on the performance of upstream turbineupstream turbine

Adaramola & Krogstad (2011)Adaramola & Krogstad (2011)


Previous studies on upstream turbine operating (yaw) conditionsPrevious studies on upstream turbine operating (yaw) conditions

Pri Mamidipudi (2011) Yaw control: The forgotten controls problemPri Mamidipudi (2011) Yaw control: The forgotten controls problem

• It was found that there is a cosIt was found that there is a cos3 3 dependency between loss of power and yaw dependency between loss of power and yaw angle especially between -20angle especially between -20ᵒ ᵒ and +20and +20 ᵒo for a scaled wind turbine model. for a scaled wind turbine model.

Effect of yaw angle on the wind turbine performanceEffect of yaw angle on the wind turbine performance


0 10 20 30 40 50 600.0

0.2

0.4

0.6

0.8

1.0

1.2

R

elat

ive

pow

er P

/P0-

yaw

low turbulence inflow high turbulence inflow

cos

2D

U∞

0 10 20 30 40 50 600.0

0.2

0.4

0.6

0.8

1.0

1.2

Rel

ativ

e T

hrus

t For

ce F

/F0-

yaw


cos

P () ≈ 0.5Cp AU⍴ eff3

P () ≈ 0.5Cp AU⍴ ∞3cos3()

P () ≈ cos3()P0_yaw

F() ≈ 0.5Cp AU⍴ eff2

F() ≈ 0.5Cp AU⍴ ∞2cos2()

F() ≈ cos2() F0_yaw

Uhub = 5.1 m/s – high turbulence inflowUhub = 6.1 m/s – low turbulence inflow


0 10 20 30 40 50 600

1

2

3

4

Tip

Spe

ed R

atio

()


2D

U∞


Vertical velocity profile at x/D =2 downstream:Vertical velocity profile at x/D =2 downstream:

2D

U∞

Wake is deflected sideways by yawing the Wake is deflected sideways by yawing the upstream turbine which results in reduced upstream turbine which results in reduced velocity deficit in the wake.velocity deficit in the wake.

Effect of yawing the upstream turbine is less Effect of yawing the upstream turbine is less pronounced in the wake for the high pronounced in the wake for the high turbulence flow due to the highly turbulent turbulence flow due to the highly turbulent nature of the flow – turbulent mixing.nature of the flow – turbulent mixing.

Low turbulenceLow turbulence

High turbulenceHigh turbulence


The overall efficiency of the wind farm (2 turbines):The overall efficiency of the wind farm (2 turbines):

Effects of upstream turbine yaw angleEffects of upstream turbine yaw angle

Decrease the upstream wind turbine power Decrease the upstream wind turbine power output with a cosoutput with a cos33 dependency between loss of dependency between loss of power and yaw angle power and yaw angle

Increase the power output of downstream Increase the power output of downstream wind turbinewind turbine

For the low turbulence inflowFor the low turbulence inflow,, the increase the increase of overall power output is up to 6% at an of overall power output is up to 6% at an appropriate upstream turbine (appropriate upstream turbine (αα=10˚) yaw =10˚) yaw angle angle

For the high turbulent inflowFor the high turbulent inflow,, yawing the yawing the upstream turbine does not make any upstream turbine does not make any improvement on the overall wind farm power improvement on the overall wind farm power outputoutput

Low turbulenceLow turbulence

High turbulenceHigh turbulence

Investigation of wake interference effects – EInvestigation of wake interference effects – EComplex terrain (2D-Ridge) effectsComplex terrain (2D-Ridge) effects

CASE 1 – Moderate slope (H/L = 0.22), slope = 12˚CASE 1 – Moderate slope (H/L = 0.22), slope = 12˚

CASE 2 – High slope (H/L = 0.41), slope = 22˚CASE 2 – High slope (H/L = 0.41), slope = 22˚

• Separation on the lee side (effect of the slope)Separation on the lee side (effect of the slope)

(reduced mean speed and higher turbulence levels)(reduced mean speed and higher turbulence levels)

• Speed-up effectsSpeed-up effects

(Higher wind speeds, great potential for energy production)(Higher wind speeds, great potential for energy production)

According to Arya (1988), the largest speed-According to Arya (1988), the largest speed-ups are observed over three-dimensional hills ups are observed over three-dimensional hills of moderate slope.of moderate slope.

3D Hills are found to produce lower wind 3D Hills are found to produce lower wind speed increases than 2D Ridgesspeed increases than 2D Ridges


3D3D3D3D 3D3D 3D3D

Moderate slope 2D-RidgeModerate slope 2D-RidgeSlope =12° Slope =12°

h/2h

Gaussian curve:Gaussian curve:2

exp 0.5 , 1.1774x

z h L

3D3D3D3D 3D3D 3D3D

High slope 2D-RidgeHigh slope 2D-Ridge Slope =22° Slope =22°

h/2h

DD

pos1 pos2 pos3 pos4 pos5

3D3D3D3D 3D3D 3D3D

Flat surfaceFlat surface


Mean velocity and turbulence intensity profileMean velocity and turbulence intensity profile

Wind turbine positionWind turbine position pos1pos1 pos2pos2 pos3pos3 pos4pos4 pos5pos5 TotalTotal

Power output Power output flat surfaceflat surface

(normalized with power output of single (normalized with power output of single

wind turbine sited on flat surface )wind turbine sited on flat surface )

1.001.00 0.830.83 0.760.76 0.75 0.75 0.740.74 4.084.08

Power output Power output moderate slope 2D-Ridgemoderate slope 2D-Ridge



0.910.91 0.820.82 1.691.69 1.02 1.02 0.730.73 5.175.17

(~26% more)(~26% more)

Power output Power output high slope 2D-Ridgehigh slope 2D-Ridge



0.920.92 0.630.63 1.331.33 0.04 0.04 0.190.19 3.113.11

(~24% less)(~24% less)


6D6D 6D6D 6D6D 6D6D

Moderate slope 2D-RidgesModerate slope 2D-Ridges

• Measuring the characteristics of surface winds over complex terrains (hill and valley )Measuring the characteristics of surface winds over complex terrains (hill and valley )

• The performances of single wind turbine sited over different locations over complex terrainsThe performances of single wind turbine sited over different locations over complex terrains


6D6D 6D6D 6D6D 6D6D

Moderate slope 2D-RidgesModerate slope 2D-Ridges

Wind turbine positionWind turbine position pos1pos1 pos2pos2 pos3pos3 pos4pos4 pos5pos5

Two hillTwo hill

Thrust Coefficient CThrust Coefficient CTT 0.1170.117 0.2820.282 0.0930.093 0.2980.298 0.1310.131

Bending moment Bending moment Coefficient CCoefficient CMZMZ

0.1240.124 0.2580.258 0.0960.096 0.2840.284 0.1300.130

Wind turbine positionWind turbine position pos1pos1 pos2pos2 pos3pos3 pos4pos4 pos5pos5

Power outputPower output



0.900.90 1.911.91 0.670.67

2.132.13 0.910.91

SUMMARYSUMMARY

• Factors affecting the complex dynamics of the wind farms Factors affecting the complex dynamics of the wind farms were investigated in detail; were investigated in detail;

Turbine spacingTurbine spacing

Wind farm layout (aligned and staggered)Wind farm layout (aligned and staggered)

Upstream turbine operating (yaw) conditionsUpstream turbine operating (yaw) conditions

Terrain effects (flat and complex terrain)Terrain effects (flat and complex terrain)

Incoming flow character and its interaction with different wind Incoming flow character and its interaction with different wind

farm layoutsfarm layouts

Thank you!Thank you!

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OUTLINE