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.