Comparison of Wind Sensors Ultrasonic versus Wind Vane/Anemometer Kenneth G. Wastrack Doyle E.
Download ReportTranscript Comparison of Wind Sensors Ultrasonic versus Wind Vane/Anemometer Kenneth G. Wastrack Doyle E.
Comparison of Wind Sensors Ultrasonic versus Wind Vane/Anemometer
October 2000
Kenneth G. Wastrack Doyle E. Pittman John E. Hatmaker L. Wayne Hamberger Tennessee Valley Authority
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Background
Problem - Obsolete Wind Sensors
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Difficulty obtaining spare parts (sensor, switch controller, etc)
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Routine bearing replacement
–
Occasional history of mechanical failures
Requirements - Sensor Specifications
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Comply with RG 1.23 requirements.
»
Wind direction +/-5 degrees.
»
Wind speed +/-0.5 mph.
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Less maintenance than existing sensors.
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Vaisala 425AH Ultrasonic Wind Sensor
Sonic Wind Sensors
– –
All-electronic Minimal maintenance
Vaisala* (formerly Handar) 425AH ultrasonic wind sensor most suitable
– – –
Manufacturer specifications Capabilities for integration System meets RG 1.23
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System Performance
RG 1.23
Climet Vaisala Wind Direction Wind Speed +/- 5 deg +/- 4.6 deg +/- 4.7 deg +/- 0.5 mph +/- 0.48 mph +/- 0.48 mph
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Principle of Operation
Transmit signal along axis
Send in reverse direction
Calculate time differences
Convert to WS along axis
Repeat for other axes
Compute WD and WS
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1.0
0.5
0.0
-0.5
-1.0
Wind Tunnel Tests
0.6
0.4
0.2
0 -0.2
-0.4
-0.6
34 28 22
Upper Limit
16 10 6 3 3 6 10
Nominal Test Speed (mph)
16
Lower Limit
22 28 34 41 Knoxville Speed Error (@10 mph) Oak Ridge Speed Error (@30 mph)
Wind Direction (degrees)
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Field Tests
Establish that sensor works as expected.
Document that data are comparable to wind vane/anemometer data.
Verify software and hardware changes.
Provide maintenance experience.
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Field Sampling Configuration
wind vane/ anemometer ultrasonic wind sensor ultrasonic wind sensor
~3.4 meters Tower width ~ 1.2 meters (48 inches)
Meteorological Tower Anemometer mounted due North of wind vane.
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Comparison of Wind Roses
Climet Vaisala
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Statistical Results
count (N) - nondimentional minimum difference maximum difference systematic difference (d) est. standard deviation of difference (s) operational comparability (C) skewness (M) - nondimentional kurtosis (K) - nondimentional
correlation coefficient - nondimentional
Note:
VWD (°) 7973 -10 10 0 2.4
2.4
0.2
-0.2
1.000
Differences in 15-minute values (Climet minus Vaisala) VWS (mph) AWS (mph) 7833 -3.8
1.0
0.0
0.37
0.37
-1.64
10.90
0.998
7827 -3.9
1.0
0.0
0.37
0.37
-1.62
10.80
0.998
N, d, s, C, M, K are specified in ASTM D 4430-96, “Standard Practice for Determining Operational Comparability of Meteorological Measurements”.
ST (°) 7976 -9 9 0 0.9
0.9
-1.4
24.3
0.975
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Problems Encountered
Wind Tunnel Tests
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Tunnel Configuration
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Echo Effect
Software Changes
Alignment Error
Error Handling
Tower Shadow Effect
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Results
Vaisala Ultrasonic Wind Sensor is equivalent to the existing Climet wind vane/anemometer system.
Additional Benefits
Lower starting threshold
Continued functioning during icing conditions
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Pre-Operational Issues
EMI/RFI potential
Uniformity of sensors
Changes to operational practices and revision of procedures
System Changes
Removal of wind translators
Connection of ultrasonic sensors directly to data logger computer
Software changes
Discontinue strip-charts
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Conclusion
The Vaisala ultrasonic wind sensor meets the accuracy requirements of RG 1.23 and can be used as a replacement for the Climet wind speed/anemometer system.
TVA plans to install the ultrasonic wind sensors at its nuclear plants as soon as EMI/RFI testing is completed and applicable documentation (procedures, FSARs, etc.) are updated.
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