Www.windtest-nrw.de windtest grevenbroich gmbh Wang,Qi Power performance measurement techniques...

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windtest grevenbroich gmbh

Wang,Qi

Power performance measurement techniques 功率特性测量技术

2www.windtest-nrw.de

Table of contents

• Introduction.

• Physics of the wind.

• Instrumentation.

• How it works.

• Measurements and measurement procedures.

• Evaluation of the power performance.

• Small wind turbines.


Introduction

• The acoustic noise measurement technique is based on the IEC 61400-12-1.

• The purpose is to ensure consistency, reproducibility and accuracy in measurement and analysis of power performance by wind turbine generator system.

• The standard provides guidance in the measurement, analysis and reporting of power performance testing.

• The key element of power performance testing is the measurement of wind speedwind speed.


Introduction

• Procedural overview.

Power Performance Measurement

End Of Power Performance Measurement

Finial Analysis:

- Power Curve- AEP Calculation

- C Calculation- Uncertanty Assessment

P

Data Correction

Store Database

Reporting And

Documentation

Filter Data For:- Wind Speed- Wind Direction- Turbine Online- Failure Or Degration

Of Test Equipment

Data Collection

Setup Test Equipment

Site Calibration According To Annex C

Test Site If Fulfill Annex B

AssessmentNO YES


Power of the wind

dxAV

dxAVm

2

2

1vmEKin

2

2

1v

dt

dm

t

EP

32.1m

kg

V

m

vAdt

dxA

dt

dm

3

2

1vAP

Energy

Density

Mass

Volume

Power

Mass Flow

A

v

dx

V


Extracted mechanical power Pmech

3 31 3 1 1 3 3

1

2mechP P P A v A v

v1

F1

v2

F2

v3

F3

Pmech

1 1 2 2 3 3

13 1

3

2 21 1 1 3

1

2mech

v A v A v A

vA A

v

P A v v v

Constant mass flow

Maximum:

3110max 2

13

vAPPvmechmech


Power coefficient cp

231

2

vvv

v1

F1

v2

F2

v3

F3

Pmech

)(2

131222 vvAvA

23

2122

23

2111 2

1

2

1vvvAvvvAPmech

3123

2124

1vvvvAPmech

3120 2

13

vAPv

1

32 112

1

v

vaaa

P

Pc mechp


Maximum power coefficient cp

0da

dcp

v1

F1

v2

F2

v3

F3

Pmech%3,59593.0

27

16max

pc

Maximum)1()1(2

1 2 aacp

)1(2

1 32 aaacp

)321(2

1 2aada

dcp

0321 2 aa

3

1

1

3 v

va

Betz factor


Summary

%3,59593.0max

pc

Power of the wind

Betz Factor

3

2

1vAP

Extracted mechanical Power

3

2

1vAcP pmech

wind

tip

v

v

Tip Speed Ratio

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Power coefficient cp example

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Power coefficient cp example

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Instruments

• Electric power.

– Power transducer: shall fulfill IEC 60688 Class 0.5 or better.

– Not a power transducer: the accuracy should be equivalent to Class 0.5 power transducers.

– The full-scale range of measurement device should be set to -50% to +200% of the rated power.

• Anemometers.

– Should use the class better than 1.7A.

– Should use the class better than 2.5B or 1.7S if site calibration requiring.

– The difference between the regression lines of calibration and recalibration shall be within ±0.1 m/s in the range 6 m/s to 12 m/s.

– The cup anemometer shall be mounted at hub height of ±2.5%.

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Instruments

• Wind direction transducer.

– The combined calibration, operation, and orientation uncertainty shall be less than 5°.

• Air density.

– Shall be derived from the measurement of air temperature and pressure.

– At high temperature, it is recommended also that relative humidity be measured and corrected for.

– Thermometer.• Shall be mounted within 10 meter of hub height.

– Hygrometer.

– Barometer. • Shall be corrected to the hub height according to ISO 2533.

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Instruments

• Rotational speed and pitch angle.

– If specific need, i.e. measurements connection with acoustic noise tests.

• Blade condition.

– Particularly for stall regulated turbines.

– Precipitation, icing and bug etc.

• Data acquisition system (DAS).

– Sampling rate per channel of at least 1Hz shall be used.

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How it works

• Wind speed measurement.

– The shaft of an anemometer is coupled to an electrical transducer which produces an electrical output signal, typically a DC voltage proportional to shaft rotation rate and therefore to wind speed.

Wind SpeedCup

Shaft Rotation Electrical transducer

Frequency

faaVW 0

– The wind speed can be calculated from the frequency in online-famos using equation:

VW : Wind speeda0 : The regression coefficient [m/s]a : The regression coefficient [m/s/Hz].f : Frequency

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How it works

• Wind speed measurement.

Pulse signal transformation

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How it works

• Wind direction measurement.

– When the wind blows past the vane, the change of wind direction is measured by the sensor as the aerodynamics of the counter-weight and the tail try to keep aligned to the path of the wind. The motion of the wind vane is translated to the potentiometerpotentiometer shaft causing a change in the potentiometer's resistance, as a change in voltage.

Wind vane direction Potentiometer

2K Ohm

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How it works

• Temperature measurement.

– PT100 is a temperature-dependent resistance. It has 100 ohms with 0°C , the temperature coefficient amounts to depending upon platinum material +0.385 ohm/ °C. The voltage drop at the platinum sensor rise with increasing temperature and concomitantly the difference at the instrument amplifier.

• Humidity measurement.

– The capacitive sensors sense water by applying an AC signal between two plates and measuring the change in capacitance caused by the amount of water present. The resistive sensors use a polymer membrane which changes conductivity according to absorbed water.

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How it works

• Temperature and humidity measurement.

UV

mbarmbarP

5

260800

Meteorological box

• Pressure measurement.

– PTB100 barometers feature the silicon capacitive absolute pressure sensor. The sensor have 0-5 VDC output and 800-1060 mbar pressure range.

– The barometric pressure can be calculated from the measured output voltage using a simple equation:

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Measurements and measurement procedures

• Location of the meteorological mast and measurement sector.

– Shall be positioned at a distance from the wind turbine of between 2D and 4D of the wind turbine, 2.5D is recommended.

Distance of the meteorological mast and maximum allowed measurement sectors

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Table B.1 Test site requirements: topographical variations

• Assessment of terrain at the test site.

– If the terrain complies with the requirements of Table B.1, then no site calibration is required.

– If wind speed different between the anemometer position and the turbine’s hub less than 1% at 10 m/s for the measurement sectors, then no site calibration is required.

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• Measurement procedure.

– General• The measurement procedure shall be documented, as detailed in

Clause 9.

• Accuracy of the measurements shall be expressed as described in Annex D.

• During the measurement period, data should be periodically checked, and the test logs shall be maintained to document all important events.

– Wind turbine operation.• Shall be in normal operation and the machine configuration may not

be changed.

• Any special maintenance actions during the test shall be noted.

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– Data collection.• Selected data sets shall be base on 10-min periods derived from

contiguous measured data.

• Data shall be collected continuously at a sampling rate of 1 Hz or higher.

• Air temperature, pressure, wind turbine status and precipitation may be sampled at a slower rate, but at least once per minute.

• The data shall store either sampled data or statistics of data sets as:

» Mean value.» Standard deviation.» Maximum value.» Minimum value.

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– Data rejection.• To ensure that only data obtained during normal operation are used

in analysis and data are not corrupted. Data sets shall be excluded following circumstances:

» Wind speed are out of the operating range;» Turbine fault, manually shutdown, in test or maintenance

operating mode;» Failure or degradation of test equipment;» Wind directions outside valid sectors.

• To ensure that only data obtained during normal operation are used in analysis and data are not corrupted. Data sets shall be excluded following circumstances:

» Wind speed are out of the operating range;» Turbine fault, manually shutdown, in test or maintenance

operating mode;» Failure or degradation of test equipment;» Wind directions outside valid sectors.

• Two data sets shall be presented because the effect of hysteresis. One shall include all data points (Database A), the other shall exclude the turbine has stopped generating power due to cut-out at high wind speed (Database B).

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– Data correction.• Wind speed shall be corrected for flow distortion from site

calibration.

• Air pressure shall be corrected if measured at 10 meter difference that closed to hub height.

– Database.• Filtered database shall include a minimum of 180 h of sampled

data.

• Each bin shall include a minimum of 30 min of sampled data.

• The selected data sets shall at least cover a wind speed range extending from 1 m/s below cut-in to 1,5 times the wind speed at 85% of the rated power of the wind turbine.

• Alternatively, the wind speed range shall extend from 1m/s below cut-in to a wind speed at which "AEP-measured" is greater than or equal to 95% of "AEP-extrapolated"

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Evaluation of the power performance.

21

1 1iiN

i iih

PPVFVFNAEP

• AEP (annual energy production).

– AEP is estimated by applying the measured power curve to different reference wind speed frequency distributions.

– AEP shall be made for hub height annual average wind speed of 4, 5, 6, 7, 8, 9, 10 and 11 m/s according to :

2

4exp1

aveV

VVF

and

Nh: number of hours in one year ≈8760N: number of binsVi : normalized and averaged wind speed in bin iPi: normalized and averaged power output in bin iVave: annual average wind speed at hub heightV: wind speedF(V): the Rayleigh cumulative probability distribution

function for wind speed

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• AEP (annual energy production).

V_annual, hub height

(Rayleigh)AEP measured

AEP extrapolat

ed

AEP extra / AEP meas.

m/s kWh kWh %

4 12624 12624 100

5 24081 24099 100

6 37427 37715 101

7 50179 51705 103

8 60341 64800 107

9 67094 76246 114

10 70599 85610 121

11 71494 92697 130

Reference air density 1.225 kg/m³

Cut out wind speed 25 m/s

AEP calculation

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N

j jini

i VN

V1 ,,

1

• Measured power curve.

– Determined by “method of bins” for the normalized dataset.

– Using 0.5 m/s bins and calculation of the mean values of wind speed and power output for each bin according to:

and

Vi : normalized and averaged wind speed in bin iVn,i,j : normalized wind speed of dataset j in bin iPi: normalized and averaged power output in bin iPn,i,j : normalized power output of dataset j in bin iNi: number of 10 min datasets in bin i

N

j jini

i PN

P1 ,,

1

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• Power coefficient

– Ratio of the net electric power output of a wind turbine to the available power in the free stream wind over the rotor swept area.

– Shall be determined from the measured power curve according to:

and

0 : reference air density (1.225 kg/m³)A : swept area of the wind turbine rotor Pi: normalized and averaged power output in bin iVi : normalized and averaged wind speed in bin iCP,i: Power coefficient in bin i

3,0

,,

21

icorr

icorriP

vA

PC

4

2rotord

A

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• Power coefficient

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

0,45

0,50

0 2 4 6 8 10 12 14 16 18

Hub height wind speed [m/s]

Po

we

r [k

W]

Power coefficient CP

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• AEP and power curve.

q6_Calulation2ClassVW: PMeanBinMean_VwAuswertMeanBinMeanExistingq6_Calulation2ClassVW: PMeanBinMean_VwAuswertMeanBinMean85Prozq6_Calulation2ClassVW: PMeanBinMean_VwAuswertMeanBinMeanAepExtrq6_Calulation2ClassVW: AEP_VWMean1aMeasq6_Calulation2ClassVW: AEP_VWMean1aExtr

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.910 3̂ kW

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.510 6̂ kW h

5 10 15 20

m /s

AEP and power curve measured and extrapolated

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• Measured power curve and corrected to sea level.

Measured power curve and corrected to sea level 1.225 kg/m³

Bin

No.v P n cp

Unc

Cat. AI* I-std* α* α-std*

Bin

No.v P n cp

Unc

Cat. AI* I-std* α* α-std*

m/s kW kW % % m/s kW kW % % 1 0.533 -2.83 22 -6.061 0.2 0.562 0.212 0.061 0.120 25 12.512 1719.15 196 0.285 2.3 0.072 0.025 0.089 0.0792 1.030 -2.75 59 -0.816 0.2 0.354 0.107 0.073 0.047 26 13.012 1751.35 164 0.258 1.7 0.077 0.027 0.078 0.1083 1.516 -1.96 84 -0.182 0.3 0.261 0.083 0.081 0.072 27 13.510 1767.39 161 0.233 1.1 0.072 0.024 0.085 0.0794 2.014 -1.34 90 -0.053 0.4 0.230 0.102 0.086 0.097 28 13.999 1780.04 147 0.211 0.8 0.077 0.024 0.088 0.0975 2.511 1.44 131 0.030 0.5 0.171 0.082 0.070 0.130 29 14.497 1790.30 149 0.191 0.6 0.077 0.019 0.085 0.0996 2.994 13.62 130 0.165 1 0.164 0.073 0.076 0.069 30 14.989 1796.70 147 0.173 0.5 0.078 0.019 0.063 0.1587 3.493 37.95 165 0.289 1 0.137 0.064 0.082 0.093 31 15.469 1798.95 124 0.158 0.4 0.077 0.020 0.080 0.1058 4.015 67.44 142 0.339 1.3 0.129 0.078 0.073 0.088 32 15.986 1801.28 87 0.143 0.4 0.079 0.019 0.083 0.0879 4.505 106.40 131 0.378 1.7 0.116 0.047 0.091 0.080 33 16.480 1801.53 97 0.131 0.3 0.082 0.020 0.083 0.17210 4.995 145.73 139 0.380 2.1 0.100 0.039 0.089 0.147 34 17.001 1801.36 72 0.119 0.5 0.081 0.021 0.067 0.11211 5.477 199.10 145 0.394 2.3 0.101 0.043 0.085 0.117 35 17.486 1801.74 60 0.109 0.4 0.085 0.016 0.060 0.11912 5.993 268.00 156 0.404 2.6 0.093 0.041 0.081 0.102 36 17.991 1801.95 53 0.101 0.4 0.085 0.021 0.080 0.06813 6.506 349.64 158 0.412 3.4 0.095 0.044 0.070 0.082 37 18.504 1800.15 77 0.092 0.4 0.088 0.018 0.087 0.06814 7.006 437.23 203 0.413 3.5 0.088 0.048 0.067 0.096 38 19.000 1800.93 40 0.085 0.5 0.091 0.016 0.060 0.10015 7.509 545.88 218 0.419 3.9 0.082 0.041 0.074 0.092 39 19.487 1800.87 50 0.079 0.5 0.091 0.015 0.062 0.10316 8.001 654.89 204 0.415 3.7 0.083 0.043 0.064 0.064 40 20.004 1799.71 51 0.073 0.6 0.090 0.014 0.072 0.07117 8.499 784.75 210 0.415 4.6 0.076 0.035 0.088 0.097 41 20.528 1800.91 47 0.068 0.8 0.088 0.016 0.081 0.06918 8.986 918.89 201 0.411 4.9 0.076 0.033 0.060 0.088 42 21.036 1800.19 54 0.063 0.7 0.086 0.013 0.080 0.05719 9.499 1071.79 221 0.406 4.6 0.080 0.036 0.073 0.091 43 21.455 1799.85 50 0.059 0.7 0.087 0.012 0.087 0.06820 10.003 1205.82 200 0.391 3.5 0.078 0.034 0.072 0.091 44 21.962 1799.89 37 0.055 0.5 0.089 0.016 0.050 0.08921 10.512 1334.95 215 0.373 3.4 0.079 0.030 0.084 0.110 45 22.476 1799.54 27 0.051 0.7 0.085 0.013 0.058 0.06922 10.990 1447.86 201 0.354 3.4 0.082 0.028 0.075 0.096 46 22.975 1799.74 22 0.048 0.7 0.083 0.009 0.078 0.05223 11.488 1548.04 172 0.332 4 0.079 0.027 0.077 0.140 47 23.494 1797.76 8 0.045 0.5 0.083 0.011 0.062 0.04424 12.012 1656.06 153 0.310 3.1 0.074 0.031 0.077 0.066 48 23.898 1800.40 5 0.043 0.5 0.085 0.008 0.090 0.029

Measured Power Curve Measured Power Curve* : without air density correction * : without air density correction

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• Measured power curve and corrected to sea level.

Measured power curve and corrected to sea level

PMean_VwAuswertMeanPStDev_VwAuswertMean

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.910^3 kW

0

50

100

150

200

250

300

350

400

450

500

550

600

650kW

-5 0 5 10 15 20 25 30 35m/s

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Small wind turbines

• Small wind turbines require special provisions.

– When battery charging performance, the wind turbine generator system shall include the turbine, tower, controller (may incl. dump load), and wiring between the turbine and the load.

– When system output to a grid, shall be noted above if the charge controller and dump load are used.

– The wind turbine shall be connected to an electrical load that is representative of the load for which the turbine is designed.

– If no specific mounting system, the generator should be mounted at a hub height of at least 10 meter.

– The connection to the load shall be no closer than the base of the turbine tower and no farther than three times the tower height.

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Small wind turbines


– If more practical to mount the anemometer to the tower, a separate meteorological mast is not required, but all such components shall be located at least 3 meter away from any part of the rotor.

– The air temperature and pressure sensor shall be mounted at least 1.5 rotor diameter below hub height even if such mounting results less than 10 meter above ground level.

– All subsequent references to 10-min datasets in the standard shall apply to 1-min datasets, and the datasets has met the following criteria:

• Each wind speed bin between 1 m/s below cut-in and 14 m/s shall contain a minimum of 10 min of sampled data.

• The total database contain at least 60 hours of data within the wind speed range.

• In the case of furling turbines, the database should include completed wind speed bins characterizing performance when the turbine is furled.

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Small wind turbines


– In cases the turbine does not shut down in high winds, AEP measured and AEP projected shall be calculated as though cut-out wind speed were the highest, filled wind speed bin or 25 m/s, whichever is greater.

– It is recommended that additional performance data be obtained to quantify the effect that changes of battery bank voltage have on turbine performance. These additional power curves should be obtained by setting the battery bank voltage to the optional low and high settings, and at least 30 h of data using 1-min pre-averaging.

Battery bank voltage settings

Nominal voltage Required setting Optional low setting optional high setting

12 12.6 11.4 14.4

24 25.2 22.8 28.8

36 37.8 34.2 43.2

48 50.4 45.6 57.6

Other 2.1* 1.9* 2.4*

*volts per cell

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Thank You For Your Attention!

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