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Numerical Site Calibration on a Complex Terrain and Numerical Site Calibration on a Complex Terrain and its Application for Wind Turbine Performance Measurementsits Application for Wind Turbine Performance Measurements
Toshiyuki SANADA Toshiyuki SANADA (Mechanical Engineering Science, Kyushu University, Japan) (Mechanical Engineering Science, Kyushu University, Japan)
EWEC06 (2006.2.28, Athens)
Masatoshi FUJINOMasatoshi FUJINO
Daisuke MATSUSHITADaisuke MATSUSHITA
Takanori UCHIDATakanori UCHIDA
Hikaru MATSUMIYAHikaru MATSUMIYA
Masao WATANABEMasao WATANABE
Yoshinori HARAYoshinori HARA
Minori SHIROTAMinori SHIROTA
Supported by NEDO (New Energy Development Organization)Standardization research of wind turbine in Japan
Fluid Dynamics Lab, Kyushu University
Outline 1Outline 1
Numerical Site CalibrationNumerical Site Calibration
Reference meteorological mast
Wind Speed at a wind turbine
Wind speed Meteorological mast
CFD (Computational Fluid Dynamics)
EWEC06 (2006.2.28, Athens)
A pair of masts
Outline 2Outline 2
Flow Correction Factor due to Complex TerrainFlow Correction Factor due to Complex Terrain
LES
GIS
Prediction of wind speedPrediction of wind speed
Wind Turbine Performance Wind Turbine Performance MeasurementsMeasurements
EWEC06 (2006.2.28, Athens)
0 1000 2000 3000
4
6
8
10
time [s]
win
d sp
eed
[m/s
]
measured prediction
0
100
200
300
400
500
600
700
0 5 10 15 20
measured designed
P (
kW)
UWT
(m/s)
Meteorological mast
IntroductionIntroduction
~ Wind Turbine in Japan ~~ Wind Turbine in Japan ~
Ratification of Kyoto Protocol
Renewable Portfolio Standard (RPS) Law
Renewable energy
1.35% of total electricity supply(2010)
Wind powerWind power
March, 2004 926 MW
2010 3,000 MW (the official government target)
2030 11,800 MW (the new target of JWPA)
Complex terrainComplex terrain, Typhoon, Turbulence, Gust, Thunder storm …
almost 1/10 of Germany’s !!almost 1/10 of Germany’s !!
Challenges for Japanese wind turbine developmentChallenges for Japanese wind turbine development
Prediction of wind power generation
Wind Turbines in JapanWind Turbines in Japan
Complex TerrainComplex Terrain
mountain area 73% planes 14%
50% of the people live in plains.
Wind Turbine Performance Wind Turbine Performance MeasurementsMeasurements at Complex Terrain at Complex Terrain
for Japanese wind turbine developmentfor Japanese wind turbine development
for next step…for next step…
IntroductionIntroduction
~ Wind Turbine in Japan ~~ Wind Turbine in Japan ~
Performance MeasurementsPerformance Measurements
たかしま D
H2 H1
H1=H2
V1V2
L=2~4D (with in the measurement sector)
V1=V2
wind speed at reference
mast = wind speed at wind turbine
wind speed not influenced by wind turbine
Example
requirement of high accuracy in measuring wind speed
IEC61400-12-1
IntroductionIntroduction
Site Calibration Complex Terrain
Flow correction factor Flow correction factor (=the wind speed at the wind turbine location divided by the wind speed at the meteorology mast)
H2
H1H1=H2
V1V2
L=2~4D (with in the measurement sector)
たかしま
V1= f (V2)
the posi tion where WTGS i s scheduled to be set up.
Test site requirementsTest site requirements (topographical variations)
・Maximum slope <5% ( between 2L and 4L)
・ Eliminate the direction > 0.02 in between neighboring sector
・ Each wind direction bin, no larger than 10°IEC61400-12-1
IntroductionIntroduction
V1=V2
Wind Turbine Performance MeasurementsWind Turbine Performance Measurements
Imamura et al. (EWEC01)
• Complex terrain that fails to satisfy the IEC standard
• Two points correlation analysis (before WT is constructed)
• Correlation equation using 10miniuts average.
• Direction with high correlation
(eliminate the direction with high turbulent intensity)
After measurements….,After measurements….,
If there is no direction with high correlation?If there is no direction with high correlation?
COSTCOST
RISKRISK
IntroductionIntroduction
Site Calibration Japan
ObjectiveObjective
• To propose a numerical site numerical site calibrationcalibration, which employs CFD for wind field simulation over a complex terrain to evaluate flow flow correction factorcorrection factor.
MethodsMethodsMeasurements
Numerical Analysis
H2
H1H1 = H2
V1
V2
L=2~4D (with in the measurement sector)
たかしま
V1= f (V2)
1
3
• To measure the wind speed at reference mast
• To calculate the flow correction factor using CFD
• To correct the wind speed using • To evaluate the wind turbine performance
V1=V2V2
たかしま
(x2, y2, z2)
(x1, y1, z1)V1
CFD(Computational Fluid Mechanics)
2
V1=V2
Numerical AnalysisNumerical Analysis
RIAM-COMPACT (Uchida & Ohya, 1999, 2003)
LES (Large Eddy Simulation)Grid scale vortex : Navier-Stokes Eq.
Sub-grid scale vortex : model
Nonlinear, Unsteady simulation ! Nonlinear, Unsteady simulation !
time series analysistime series analysis
• correlation
• turbulent intensity
etc…
coordinate system generalized curvilinear coordinate
variable arrangement collocated arrangement
discretization method finite-difference method
coupling algorithm fractional step method
time advancement method Euler explicit method
poisson equation for pressure
SOR method
convective terms3rd-order upwind scheme based on an interpolation
method (=0.5)
other spatial derivative term 2nd-order central scheme
SGS model Smagorinsky model + wall damping function
boundary condition
inflow 1/7 power low
top and side free-slip
outflow convective outflow
ground no-slip
Numerical AnalysisNumerical Analysis
Digital MapDigital Map
GIS (Geographic Information System) techniqueGIS (Geographic Information System) technique
aero-photograph
aero-photograph
Wind turbine performance measurements
Numerical simulation of wind turbine scale
Digital map of wind turbine scalec.f. GSI map (50m, most commonly used)
Printed atlas
CAD data
Computational GridComputational Grid 160 x 160 x 60
Test Site Test Site ~takashima~~takashima~
Point DistanceHeight
differenceMean slope
O-A 50m 25m 50%
O-B 75m 25m 33%
O-C 62.5m 25m 40%
Distance Maximum slope
<2L <3%
≥2L and <4L <5%
≥4L and <8L <10%
N
fails to satisfy the IEC standard : fails to satisfy the IEC standard : test site requirement site calibrationtest site requirement site calibration
topographical variations
Measurements Measurements
mast1: reference mast
mast2: for validity check
N
L=5.13D
Spatial configuration of WT & mast
Wind Characteristics Wind Characteristics
0
0.05
0.1
0.15N
NNE
NE
ENE
E
ESE
SE
SSE
S
SSW
SW
WSW
W
WNW
NW
NNW
0
2
4
6
8
10N
NNE
NE
ENE
E
ESE
SE
SSES
SSW
SW
WSW
W
WNW
NW
NNW
0
0.1
0.2
0.3
0.4N
NNE
NE
ENE
E
ESE
SE
SSE
S
SSW
SW
WSW
W
WNW
NW
NNW
mast1 mast2
Wind RoseWind Rose Average Wind Speed Average Turbulent Intensity Average Wind Speed Average Turbulent Intensity
[%] [m/s] [%]
NW, N, SNW, N, S
N
1st, April, 05 ~ 30th, November, 2005
How to define the flow correction factor ?
• time series of wind speed of each points
ExampleExample, North windWTM1
N
mast 1
WT
z=M1
Condition: 5m/s, 10m/s, 15m/s, 10minuts
Correction FactorCorrection Factor
• 10 minutes averaged value (corresponding to 10 minute data set)
Uncertainly analysis
1 β MWT UU
22.1
22.1 1
MWT UU
regression line (minimum mean square method)
0
5
10
15
20
0 5 10 15 20
N
UWT(m
/s)
UM1
(m/s)
correlation coefficient : high
However …
How to define the flow correction factor ?
Correction FactorCorrection Factor
2 4 6 8 10 12 14 16 180
0.2
0.4
0.6
0.8
UM1
(m/s)
(a)
2 4 6 8 10 12 14 16 180
2
4
6
UWT
(m/s)
(b)
uU
U
M
WT βi,1
i,
mast 1 WT
u=N(0, 2): component of variation from average wind speed
0
5
10
15
20
0 5 10 15 20
N
UWT(m
/s)
UM1
(m/s)
Uncertainly analysis
Assumption: bivariate normal distribution Assumption: bivariate normal distribution
Correction FactorCorrection Factor
• confidence interval 95% (±1.97)
evaluation of correction factor
β2α
error of UWT
0
5
10
15
20
0 5 10 15 20
N
UWT(m
/s)
UM1
(m/s)
=1.2241=0.1585
In this case,
=21%
High accuracy in measuring wind speed is required.
How to define the flow correction factor ?
Correction FactorCorrection Factor
The power is approximately proportional to wind speed to the third power.
Results ~Results ~ NNORTHORTH W WESTEST ~~ N
NWFlow FieldFlow Field
y=WT
y=M2
M1 WTM2
mast2: large Uz components
Mast1 & WT: flow smooth
y z
N
NW
regression analysis
=0.6%
Good direction for WT performance measurements
0
5
10
15
20
0 5 10 15 20
NW
UWT(m
/s)
UM1
(m/s)
=1.0590=0.0032
Results ~Results ~ NNORTHORTH W WESTEST ~~
Flow Correction FactorFlow Correction Factor
=1.059
N
NW
validity check : mast 1 & mast 2
Measurements (10min data-set) Calculation
12 078.1 mastmast UU
cup vs. cup
over estimation?
0
5
10
15
20
0 5 10 15 20
NW
UM2(m
/s)
UM1
(m/s)
=1.0477=0.0030
Results ~Results ~ NNORTHORTH W WESTEST ~~
Validity CheckValidity Check
y=M2
NNResults ~Results ~ NNORTHORTH ~~
Flow Field
z=mast1 z=mast1
Flow FieldFlow Field
M1 WTM1 WT
NN
regression analysis
0
5
10
15
20
0 5 10 15 20
N
UWT(m
/s)
UM1
(m/s)
=1.2241=0.1585
=21%
Poor direction for WT performance measurements
=1.2241
Results ~Results ~ NNORTHORTH ~~
Flow Correction FactorFlow Correction Factor
Results ~Results ~ SSOUTHOUTH ~~ N
SFlow Field
M1
WT
z=WT y=WT
Flow FieldFlow Field
WT
N
S
regression analysis
0
5
10
15
20
0 5 10 15 20
S
UWT(m
/s)
UM1
(m/s)
=1.0844=0.0053 =1.0%
Good direction for WT performance measurements
Results ~Results ~ SSOUTHOUTH ~~
Flow Correction FactorFlow Correction Factor
=1.0844
0
5
10
15
20
0 5 10 15 20
S
UM2(m
/s)
UM1
(m/s)
=0.4056=0.1070
What happen at the Mast 2 ?
M2WT
Siting of Meteorological mast
0
0.1
0.2
0.3
0.4N
NNE
NE
ENE
E
ESE
SE
SSE
S
SSW
SW
WSW
W
WNW
NW
NNWResults ~Results ~ SSOUTHOUTH ~~
Validity CheckValidity Check
Turbulent Intensity
=53.0% !!
Power PerformancePower Performance ~ NORTH WEST ~~ NORTH WEST ~
N
NW
0
5
10
15
20
0 5 10 15 20
NW
UWT(m
/s)
UM1
(m/s)
=1.0590=0.0032
0
100
200
300
400
500
600
700
0 5 10 15 20
North West
design
UM1
UWT
Pow
er [k
W]
Wind Speed [m/s]
Power PerformancePower Performance ~ NORTH ~~ NORTH ~
0
5
10
15
20
0 5 10 15 20
N
UWT(m
/s)
UM1
(m/s)
=1.2241=0.1585
NN
0
100
200
300
400
500
600
700
0 5 10 15 20
North
design
UM1
UWT
Pow
er [k
W]
Wind Speed [m/s]
Power PerformancePower Performance ~ SOUTH ~~ SOUTH ~
N
S
0
5
10
15
20
0 5 10 15 20
S
UWT(m
/s)
UM1
(m/s)
=1.0844=0.0053
0
100
200
300
400
500
600
700
0 5 10 15 20
South
design
UM1
UWT
Pow
er [k
W]
Wind Speed [m/s]
ConclusionConclusion
• A site calibration by employing CFD (LES and detail digital map obtaineA site calibration by employing CFD (LES and detail digital map obtained from GIS) is proposed.d from GIS) is proposed.
• A numerical site calibration can evaluate A numerical site calibration can evaluate directionaldirectional flow correction flow correction factor.factor.
• A numerical site calibration can be applied to the wind turbine performA numerical site calibration can be applied to the wind turbine performance measurements if terrain condition and flow direction are carefully chance measurements if terrain condition and flow direction are carefully chosen.osen.
• Using numerical simulation, the appropriate direction and position of mUsing numerical simulation, the appropriate direction and position of meteorological mast for site calibration where fluctuation of wind speed is eteorological mast for site calibration where fluctuation of wind speed is small, can be chosen.small, can be chosen.
• Numerical site calibration at other sites. Numerical site calibration at other sites. (validity check) (validity check)
• Measurements of wind turbine performance at Measurements of wind turbine performance at complex terraincomplex terrain (effects of flow distortion, turbulent intensity) (effects of flow distortion, turbulent intensity)
(For Japanese wind turbine development, a performance testing of WT at complex terrain is required for prediction of electric power generation)
For FutureFor Future
NN
validity check : mast 1 & mast 2
Calculation
0
5
10
15
20
0 5 10 15 20
N
UM2(m
/s)
UM1
(m/s)
=1.1120=0.1498
Measurements: north wind at mast1 = Calculation : north wind into island
Results ~Results ~ NNORTHORTH ~~
Validity CheckValidity Check
Measurements (10min data-set)
N
S
validity check : mast 1 & mast 2
0
5
10
15
20
0 5 10 15 20
S
UM2(m
/s)
UM1
(m/s)
=0.4056=0.1070
Calculation
Qualitatively good agreement
Results ~Results ~ SSOUTHOUTH ~~
Validity CheckValidity Check
Measurements (10min data-set)