comparison of wind sensors - ultrasonic versus wind vane/anemometer
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October 2000 [NUMUG] Comparison of Wind Sensors 1 of 14
Comparison of Wind Sensors - Ultrasonic versus Wind
Vane/Anemometer
Kenneth G. Wastrack
Doyle E. Pittman
John E. Hatmaker
L. Wayne Hamberger
Tennessee Valley Authority
October 2000 [NUMUG] Comparison of Wind Sensors 2 of 14
Background
Problem - Obsolete Wind Sensors– Difficulty obtaining spare parts
(sensor, switch controller, etc)
– Routine bearing replacement– Occasional history of mechanical failures
Requirements - Sensor Specifications– Comply with RG 1.23 requirements.
» Wind direction +/-5 degrees.
» Wind speed +/-0.5 mph.
– Less maintenance than existing sensors.
October 2000 [NUMUG] Comparison of Wind Sensors 3 of 14
Vaisala 425AHUltrasonic 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
October 2000 [NUMUG] Comparison of Wind Sensors 4 of 14
System Performance
RG 1.23 Climet Vaisala
WindDirection
+/- 5 deg +/- 4.6 deg +/- 4.7 deg
WindSpeed
+/- 0.5 mph +/- 0.48 mph +/- 0.48 mph
October 2000 [NUMUG] Comparison of Wind Sensors 5 of 14
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
October 2000 [NUMUG] Comparison of Wind Sensors 6 of 14
-0.6-0.4-0.20
0.20.40.6
34 28 22 16 10 6 3 3 6 10 16 22 28 34 41
Nominal Test Speed (mph)
NIS
T C
up
Min
us
So
nic
(m
ph
)
Upper Limit
Lower Limit
-1.0
-0.5
0.0
0.5
1.0
000
020
040
060
080
100
120
140
160
180
200
220
240
260
280
300
320
340
360
Wind Direction (degrees)
Win
d S
pe
ed
Err
or
(mp
h)
Knoxville Speed Error (@10 mph) Oak Ridge Speed Error (@30 mph)
Wind Tunnel Tests
October 2000 [NUMUG] Comparison of Wind Sensors 7 of 14
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.
October 2000 [NUMUG] Comparison of Wind Sensors 8 of 14
Field Sampling Configuration
Anemometer mounted due North of wind vane.
~3 m
eter
s
~90
met
ers
~93
met
ers
w in d van e/an em om eter
u ltra son icw in d sen sor
~ 3 .4 m e te r s
To w e r w id th~ 1 .2 m e te r s(4 8 in c h e s)
u ltr as o n icw in d
se n so r
M e te or o lo g ic a lTow e r
October 2000 [NUMUG] Comparison of Wind Sensors 9 of 14
Comparison of Wind Roses
Climet Vaisala
October 2000 [NUMUG] Comparison of Wind Sensors 10 of 14
Statistical Results
Differences in 15-minute values(Climet minus Vaisala)
VWD VWS AWS ST(°) (mph) (mph) (°)
count (N) - nondimentional 7973 7833 7827 7976minimum difference -10 -3.8 -3.9 -9maximum difference 10 1.0 1.0 9systematic difference (d) 0 0.0 0.0 0est. standard deviation of difference (s) 2.4 0.37 0.37 0.9operational comparability (C) 2.4 0.37 0.37 0.9skewness (M) - nondimentional 0.2 -1.64 -1.62 -1.4kurtosis (K) - nondimentional -0.2 10.90 10.80 24.3correlation coefficient - nondimentional 1.000 0.998 0.998 0.975
Note: N, d, s, C, M, K are specified in ASTM D 4430-96, “Standard Practice forDetermining Operational Comparability of Meteorological Measurements”.
October 2000 [NUMUG] Comparison of Wind Sensors 11 of 14
Problems Encountered
Wind Tunnel Tests– Tunnel Configuration– Echo Effect
Software Changes Alignment Error Error Handling Tower Shadow Effect
October 2000 [NUMUG] Comparison of Wind Sensors 12 of 14
Results
Additional Benefits
Lower starting threshold Continued functioning during icing conditions
Vaisala Ultrasonic Wind Sensor isequivalent to the existing
Climet wind vane/anemometer system.
October 2000 [NUMUG] Comparison of Wind Sensors 13 of 14
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
October 2000 [NUMUG] Comparison of Wind Sensors 14 of 14
Conclusion
The Vaisala ultrasonic wind sensor meets theaccuracy requirements of RG 1.23 and can be
used as a replacement for the Climetwind speed/anemometer system.
TVA plans to install the ultrasonic wind sensorsat its nuclear plants as soon as EMI/RFI
testing is completed and applicable documentation(procedures, FSARs, etc.) are updated.
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