Palmer WTN2011 PresentationR

8/6/2019 Palmer WTN2011 PresentationR

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Evidence Based Study ofNoise Impacting Annoyance

Presented to

Fourth International Meeting on Wind

Turbine Noise

Rome Italy 11-14 April 2011

William K.G. Palmer B.A.Sc. P. Eng.

[email protected]


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Outline of Presentation

Complaints about noise and annoyancefrom wind turbines are increasing

Some medical professionals link noiseand annoyance to adverse health effects

Engineering problem solving says lookfor changes as the cause of problems

This presentation gives a procedure tocollect and evaluate evidence ofchanges in noise levels at sites meetingregulatory approval

Discussion of resulting recommended

regulatory changes follows


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Initial Sound Level ReadingsdBA dBC dBA -C Turbines

Control 28 42-44 14-16 5000m@24%

Home 1 39.5 60-65 20.5-25 620m

@32%

Home 2 40.5-42.5 58-70 17.5-27.5 560m@72%

Home 1 40.5-41.5 60-75 19.5-33.5 620m

@72%

Home 3 41.5 60-72 18.5-30.5 450m

@50%

Home 4 41.5-42.5 60-72 18.5-29.5 450m

@50%

Home 5 40-41 60-68 20-27 650m

@35%


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Knowles Microphone

Flat 20 Hz to 8000 Hz


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1000 Hz Calibrator on Audacity Recorder

Gives editing capability to expand scale.


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1000 Hz Calibrator expanded to

0.03 second trace


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Used Audacity to Perform

Frequency Analysis


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Typical Monitoring Setup


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Data Collection

Readings were taken at a series of locations

(10 km radius from centre) within a 2 hourperiod

Same terrain, same general proximity toforested areas, same weather, fundamentally

same wind speed Recorded time, wind speed, turbine output,

weather conditions (wind direction), dBA anddBC sound levels.

Performed a minimum 30 second to 5 minuterecording

Over 250 samples taken in all seasons, fromMarch 2010 to March 2011 (and continuing)


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Sound Levels at Test Homes

Turbines Not Operating


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Sound Levels at Test Homes

Turbines Synchronized at 0%


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Turbines at 25% Output


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Comparison of Sound Levels at Homes Near and Far From Turbines ~ 25%

-80.0

-60.0

-40.0

-20.0

0.0

20.0

40.0

60.0

80.0

16 Hz 32 Hz 63 Hz 125 Hz 250 Hz 500 Hz 1000Hz 2000Hz 4000Hz 8000Hz 10oc Leq

Frequency (Hz)

TLE Jun10@0205_22% CSK Jun10@0320_22% SCH Jun10@0358_29%

A Weighting Factor A-wt TLE Jun10@0205_22% A-wt CSK Jun10@0320_22%

A-wt SCH Jun10@0358_29%


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Turbines at High Power ~ 88%


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Sound Level at Homes at Varying Distance - Wind Turbines - High

Power (88%) - 10 m wind speed ~ 8 mps

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

16 Hz 32 Hz 63 Hz 125 Hz 250 Hz 500 Hz 1000Hz 2000Hz 4000Hz 8000Hz 10oc Leq

Frequency in Hertz (Hz)

SMI Nov20 0450 CSK Nov20 0526 SR10 Nov20 0552 TLE Nov20 0630


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Winter Storm - Turbines 88%


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Observations From Data

Sound levels in low frequency octaves (16, 32,64, 125 Hz) is ~ 20 dB higher at approvedhomes compared to control home in sameenvironment

Sound levels at approved homes for 0 power,with wind speeds 1 m/s is same as sound levelat control home when wind speed is > 8m/s (30km/hr fresh breeze Beaufort F. 5)

At low frequency octaves up to 125 Hz, as windspeed increases from 1 m/s to 8 m/s, controlhome increases by 10 dB from ~ 20 to 30 dBA,approved homes increase 30 dB to 50 dBA


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Impact of Cyclical Sound

What the figures do not show is theimpact of the cyclical sound

Also have data that shows that the sound

level is strongly correlated to the turbineoutput and very weakly correlated to the

ground level wind speeds at approved

homes near turbines


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Sound at SMI Site

Nov 20, 2010


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Sound at CSK Site - Nov 20, 2010


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Sound at SCH Site - Feb 15, 2011


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Regulatory Updates

Need to consider level weighting, notA-weighting of sound levels that neglects lowfrequency components

Need to consider cyclical sound and its

increased impact and perception Need to assess the under prediction of noise

levels by models, as most audits showexcesses

Excesses above background of 3 dB arereadily perceived, 20 dB excesses areunjustified by any criteria

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