Measuring Audible Wind Turbine Noise Measuring Audible Wind Turbine - PowerPoint PPT Presentation

Measuring Audible Wind Turbine Noise Measuring Audible Wind Turbine Noise Consultation Session June 22, 2010

Introduction Our Mandate To develop an objective measurement protocol to determine the noise impact from wind turbines in the determine the noise impact from wind turbines in the audible frequency range. Session Goal To obtain comments/suggestions/concerns from participants for consideration in the development of participants for consideration in the development of the Measurement Protocol.

Agenda � Presentation of framework � Presentation of data analysis techniques � Open Forum discussion of 1 st half of framework p � Break � Open Forum discussion of 2 nd half of framework � Summary & Closing y g

Acoustic Audit vs. Complaint � Measurement protocol and methodology to remain the same for audit p gy and compliant � Initiation of process is different � Audit may require a certain sampling of turbines for a given plant � Complaint investigation may also require additional measurements Process Flow Process Flow Duty Officer to determine if Complaint Report No measurement is warranted Filed Y e s M Measurement t Audit conducted

Framework Framework Measurement Intervals (Section 4.2) ( ) LAeq will be the primary descriptor used. Additional statistical indices may be used to � complement the LAeq. � Interval time will be 1-2minutes (for both sound and wind) � � 1/3 1/3 octave band measurements are essential b d i l � Audio recordings for intervals to be used primarily for reference during post processing. Audio recordings may also be used for tonality assessment. � Total duration of measurement to be sufficient to provide at least 1 hour of data per p p integer wind speed (Section 4.4.)

Framework Framework Instrumentation Requirements (Section 4.3) q ( ) Requirements of appropriate standards and guidelines shall be satisfied (IEC, NPC) � Shall incorporate methods to reduce wind induced noise � Anemometer to have an accuracy of +/- 0.2m/s and resolution of 0.1m/s � � Anemometer to be calibrated and traceable to a test facility � Anemometer shall record in same interval as sound is captured Measurement Location (Section 4.5 & 4.6) � At receptor, located at least 5m from facade � Height to be either 4.5m or 1.5m depending on receptor � Anemometer to be located at receptor, at 10m height

Framework Framework Ambient Noise (Section 4.7) ( ) Measurements to be conducted only during nighttime hours � Ambient measurements are not required if it can be shown that sound level limits are � satisfied with background noise and turbines operational � � A Ambient noise levels to be measured over the same wind speed range bi i l l b d h i d d � Ambient noise levels are to also be measured at receptors with turbines in vicinity of receptor shut down Tonality (Section 4.8) Tonality should be assessed objectively, using the Joint Nordic Method, IEC 61400-11 or � ISO 1996-2 ISO 1996-2. � Tonal adjustment should be applied using a sliding scale as outlined in the standards.

Framework Framework Data Analysis (Section 4.9) y ( ) Only data from 19:01 until 04:59 will be used for the analysis. � Remove any intervals where rainfall occurred from one hour before and one hour after � 1-minute intervals where the max/min wind speed differs by more than 2m/s from the � average wind speed are considered “gusty events” and should not be included in data i d d id d “ ” d h ld b i l d d i d set. � Intervals with noise from insects shall be adjusted by filtering the 1/3octave bands which may be affected Up to 3 rd order polynomial regression line to be fit through the remaining data for both � “ON” and “OFF” periods The ambient curve can be logarithmically subtracted from the total sound level curve to � obtain the noise contribution from the wind plant at the receptor for integer wind speeds obtain the noise contribution from the wind plant at the receptor for integer wind speeds. � Standard deviation of data sets at integer wind speeds to be reported

Example Example Measurements with turbines operating p g

Example Example Measurements with turbines parked p

Example Example Results Wind Speed [m/s] 4 5 6 7 8 Total Sound Level [dB] 39.9 43.3 46.3 48.9 51.0 Standard Deviation [dB] 3.5 3.2 2.1 1.6 1.3 Ambient Sound level [dB] 37.4 42.0 45.5 48.1 NA Turbine Sound Level [dB] 36 38 38 41 NA

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