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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Serie: Wiley Series in Acoustics Noise and Vibration
- Sprache: Englisch
A comprehensive guide to wind farm noise prediction, measurement, assessment, control and effects on people
Wind Farm Noise covers all aspects associated with the generation, measurement, propagation, regulation and adverse health effects of noise produced by large horizontal-axis wind turbines of the type used in wind farms.
The book begins with a brief history of wind turbine development and the regulation of their noise at sensitive receivers. Also included is an introductory chapter on the fundamentals of acoustics relevant to wind turbine noise so that readers are well prepared for understanding later chapters on noise measurements, noise generation mechanisms, noise propagation modelling and the assessment of the noise at surrounding residences.
Key features:
- Potential adverse health effects of wind farm noise are discussed in an objective way.
- Means for calculating the noise at residences due to a wind farm prior to construction are covered in detail along with uncertainty estimates.
- The effects of meteorological conditions and other influences, such as obstacles, ground cover and atmospheric absorption, on noise levels at residences are explained.
- Quantities that should be measured as well as how to best measure them in order to properly characterise wind farm noise are discussed in detail.
- Noise generation mechanisms and possible means for their control are discussed as well as aspects of wind farm noise that still require further research to be properly understood.
The book provides comprehensive coverage of the topic, containing both introductory and advanced level material.
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Veröffentlichungsjahr: 2017
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Table of Contents
Cover
Title Page
Copyright
Dedication
Wiley Series in Acoustics, Noise and Vibration
Preface
Chapter 1: Wind Energy and Noise
1.1 Introduction
1.2 Development of the Wind Energy Industry
1.3 History of Wind Turbine Noise Studies
1.4 Current Wind Farm Noise Guidelines and Assessment Procedures
1.5 Wind Farm Noise Standards
1.6 Regulations
1.7 Inquiries and Government Investigations
1.8 Current Consensus on Wind Farm Noise
References
Chapter 2: Fundamentals of Acoustics and Frequency Analysis
2.1 Introduction
2.2 Basic Acoustics Concepts
2.3 Basic Frequency Analysis
2.4 Advanced Frequency Analysis
2.5 Summary
References
Chapter 3: Noise Generation
3.1 Introduction
3.2 Aeroacoustics
3.3 Aerodynamic Noise Generation on Wind Turbines
3.4 Aero-elasticity and Noise
3.5 Other Noise Sources
3.6 Summary and Outlook
References
Chapter 4: Wind Turbine Sound Power Estimation
4.1 Introduction
4.2 Aerodynamic Noise Prediction
4.3 Simple Models
4.4 Semi-empirical Methods (Class II Models)
4.5 Computational Methods (Class III Models)
4.6 Estimations of Sound Power From Measurements
4.7 Summary
References
Chapter 5: Propagation of Noise and Vibration
5.1 Introduction
5.2 Principles Underpinning Noise Propagation Modelling
5.3 Simplest Noise Propagation Models
5.4 Danish Low-frequency Propagation Model
5.5 CONCAWE (1981)
5.6 ISO9613-2 (1996) Noise Propagation Model
5.7 NMPB-2008 Noise Propagation Model
5.8 Nord2000 Noise Propagation Model
5.9 Harmonoise (2002) Noise Propagation Engineering Model
5.10 Required Input Data for the Various Propagation Models
5.11 Offshore Wind Farm Propagation Models
5.12 Propagation Model Prediction Uncertainty
5.13 Outside versus Inside Noise at Residences
5.14 Vibration Propagation
5.15 Summary
References
Chapter 6: Measurement
6.1 Introduction
6.2 Measurement of Environmental Noise Near Wind Farms
6.3 Vibration
6.4 Wind, Wind Shear and Turbulence
6.5 Reporting on Noise, Vibration and Meteorological Conditions
6.6 Wind Tunnel Testing
6.7 Conclusions
References
Chapter 7: Effects of Wind Farm Noise and Vibration on People
7.1 Introduction
7.2 Annoyance and Adverse Health Effects
7.3 Hearing Mechanism
7.4 Reproduction of Wind Farm Noise for Adverse Effects Studies
7.5 Vibration Effects
7.6 Nocebo Effect
7.7 Summary and Conclusion
References
Chapter 8: Wind Farm Noise Control
8.1 Introduction
8.2 Noise Control by Turbine Design Modification
8.3 Optimisation of Turbine Layout
8.4 Options for Noise Control at the Residences
8.5 Administrative Controls
8.6 Summary
References
Chapter 9: Recommendations for Future Research
9.1 Introduction
9.2 Further Investigation of the Effects of Wind Farm Noise on People
9.3 Improvements to Regulations and Guidelines
9.4 Propagation Model Improvements
9.5 Identification and Amelioration of the Problem Noise Sources on Wind Turbines
9.6 Reducing Low-frequency Noise Levels in Residences
References
Appendix A: Basic Mathematics
A.1 Introduction
A.2 Logarithms
A.3 Complex Numbers
A.4 Exponential Function
Appendix B: The BPM model
B.1 Boundary-layer Parameters
B.2 Turbulent Trailing-edge Noise Model
B.3 Blunt Trailing-edge Noise Model
Reference
Appendix C: Ground Reflection Coefficient Calculations
C.1 Introduction
C.2 Flow Resistivity
C.3 Characteristic Impedance
C.4 Plane-wave Reflection Coefficient
C.5 Spherical-wave Reflection Coefficient
C.6 Incoherent Reflection Coefficient
References
Appendix D: Calculation of Ray Path Distances and Propagation Times for the Nord2000 Model
D.1 Introduction
D.2 Equivalent Linear Atmospheric Vertical Sound-speed Profile
D.3 Calculation of Ray Path Lengths and Propagation Times
References
Appendix E: Calculation of Terrain Parameters for the Nord2000 Sound Propagation Model
E.1 Introduction
E.2 Terrain Effects
E.3 Approximating Terrain Profiles by Straight-line Segments
E.4 Calculation of the Excess Attenuation due to the Ground Effect for Relatively Flat Terrain with no Diffraction Edges
E.5 Calculation of the Excess Attenuation due to the Ground Effect for Relatively Flat Terrain with a Variable Impedance Surface and no Diffraction Edges
E.6 Calculation of the Excess Attenuation due to the Ground Effect for Valley-shaped Terrain
E.7 Identification of the Two Most Efficient Diffraction Edges
E.8 Calculation of the Sound Pressure at the Receiver for each Diffracted Path in Hilly Terrain
E.9 Calculation of the Combined Ground and Barrier Excess-attenuation Effects
References
Appendix F: Calculation of Fresnel Zone Sizes and Weights
F.1 Introduction
F.2 Fresnel Zone for Reflection from Flat Ground
F.3 Fresnel Weights for Reflection from a Concave or Transition Ground Segment
F.4 Fresnel Weights for Reflection from a Convex Ground Segment
Reference
Appendix G: Calculation of Diffraction and Ground Effects for the Harmonoise Model
G.1 Introduction
G.2 Diffraction Effect,
G.3 Ground Effect
G.4 Fresnel Zone for Reflection from a Ground Segment
References
Appendix H: Active Noise-control System Algorithms
H.1 Introduction
H.2 Single-input, Single-output (SISO) Weight Update Algorithm
H.3 Multiple-input, Multiple-output Weight Update Algorithm
References
Index
End User License Agreement
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Guide
cover
Table of Contents
Preface
Begin Reading
List of Illustrations
Chapter 1: Wind Energy and Noise
Figure 1.1 Schematic of typical wind turbine: LE, leading edge; TE, trailing edge.
Figure 1.2 Schematic of rotor showing ability to teeter.
Figure 1.3 Global annual energy output (TWh).
Figure 1.4 Installed capacity of wind power (2000–2014).
Figure 1.6 Annual capacity factor (2000–2014).
Figure 1.7 Wind turbine 1/3-octave band A-weighted sound power level (dB) normalised to the total A-weighted sound power level, for turbines with a power rating greater than 2 MW. The error bars show the 95% confidence interval around the mean. Data from Søndergaard (2013).
Figure 1.8 Valley between source and receiver
Chapter 2: Fundamentals of Acoustics and Frequency Analysis
Figure 2.1 Representation of a sound wave: (a) compressions and rarefactions caused in air by the sound wave; (b) graphic representation of pressure variations above and below atmospheric pressure.
Figure 2.2 Wavelength in air versus frequency at 20
C.
Figure 2.3 Threshold of hearing and equal loudness contours (data from ISO226 (2003)).
Figure 2.4 Illustration of beating with different relative amplitudes and frequency differences for a primary signal at 100 Hz.
Figure 2.5 Examples illustrating the difference between beating, AM and random amplitude variation: (a) beating; (b) pure AM; (c) typical AM signal from a wind turbine; (d) random amplitude variation.
Figure 2.6 Various weighting curves used in the assessment of noise.
Figure 2.7 Sound level in the corner of a rectangular room as function of frequency, generated by a sound source with an output that is the same at all frequencies: (a) rectangular room of dimensions 6.84 5.56 4.72 m with a loudspeaker in the corner; (b) room response from 20–80 Hz, with mode orders in the , and directions indicated on the Figure (e.g. 010); (c) room response from 80–315 Hz.
Figure 2.8 Sound generation illustrated: (a) the piston moves right, compressing air as in (b); (c) the piston stops and reverses direction, moving left and decompressing air in front of the piston, as in (d); (e) the piston moves cyclically back and forth, producing alternating compressions and rarefactions, as in (f). In all cases disturbances move to the right with the speed of sound.
Figure 2.9 Spectral analysis illustrated: (a) disturbance varies sinusoidally with time at a single frequency , as in (b); (c) disturbance varies cyclically with time as a combination of three sinusoidal disturbances of fixed relative amplitudes and phases; the associated spectrum has three single-frequency components , and , as in (d); (e) disturbance varies erratically with time , with a frequency band spectrum as in (f).
Figure 2.10 Finite impulse response (FIR) filter structure.
Figure 2.11 Infinite impulse response (IIR) filter structure.
Figure 2.12 A-weighted sound pressure levels (SPL) measured at 3:30am outside a residence 3.3 km from a 37 3.3 MW turbine wind farm, with the turbines on (black) and off (grey), for a wind speed of 10.4 m/s at the hub of the nearest turbine and 0 m/s at the measurement point. (a) A-weighted level outdoors (10-s period, 125-ms averaging or ‘fast’ response, dBA, dBA; (b) the same, but with 10-ms averaging; (c) A-weighted level outdoors (5-min period, 125-ms averaging, dBA, dBA); (d) the same but with 10-ms averaging.
Figure 2.13 C-weighted sound pressure levels (SPL) measured at 3:30am outside an unoccupied residence 3.3 km from a 37 3.3 MW turbine wind farm with the turbines on (black) and with them of (grey) for a wind speed of 10.4 m/s at the hub of the nearest turbine and 0 m/s at the measurement point. (a) C-weighted level outdoors (10-s period, 125-ms averaging or ‘fast’ response, dBC, dBC); (b) the same but with 10-ms averaging; (c) C-weighted level outdoors (5-min period, 125–ms averaging, dBC; dBC); (d) the same but with 10-ms averaging.
Figure 2.14 An example of Fourier analysis of a square wave: (a) periodic square wave in the time domain; (b) the first four harmonic components of the square wave in (a).
Figure 2.15 Various Fourier transform pairs (after Randall (1987)). The dashed lines indicate a periodically repeating sequence:
Figure 2.16 Comparison of the filter characteristics of the rectangular and Hanning time-weighting functions for a power spectrum (after Randall (1987).
Figure 2.17 Illustration of aliasing: (a) zero-frequency or DC component; (b) spectrum component at sampling frequency interpreted as DC; (c) spectrum component at ; (d) spectrum component at interpreted as . After Randall (1987).
Figure 2.18 Envelope analysis with the Hilbert transform.
Figure 2.19 Schematic arrangement for the measurement of a system transfer function (such as outside-to-inside noise levels in a house) using an MLS signal.
Figure 2.20 The next value for register bit is the modulo-2 sum of and , indicated by the symbol.
Chapter 3: Noise Generation
Figure 3.1 Two types of quadrupole: (a) the four monopoles in a lateral quadrupole; (b) the orientation of four monopoles in a longitudinal quadrupole. Each monopole is described as a circle, with its relative phase indicated by a plus or minus sign, as shown.
Figure 3.2 The turbulent energy cascade.
Figure 3.3 Phenomenological model of turbulent sound production. Adapted from Ribner (1981).
Figure 3.4 A moving, rigid body with surface , surrounded by a fluid volume . The velocity normal to a small element of the surface is illustrated.
Figure 3.5 The aerodynamic environment of a wind turbine.
Figure 3.6 The aerodynamic environment around the tower: the Figure shows a horizontal sectional view through the tower and rotor plane, illustrating the motion of the blade through the streamlines about the tower.
Figure 3.7 The aerodynamic environment of a blade tip.
Figure 3.8 Directivity patterns of trailing-edge noise using the theory of Amiet (1976). The origin is at the trailing edge location and the flow is assumed from left to right; is chord, is wavelength.
Figure 3.9 Typical 1/3-octave turbulent trailing noise spectrum, . SPL: sound pressure level. Source: Herr (2007).
Figure 3.10 Peak radiating frequency vs blade Reynolds number () for a fixed tip Mach number of .
Figure 3.11 The aeroacoustic feedback loop responsible for airfoil tonal noise generation at low Reynolds numbers.
Figure 3.12 Typical spectrum for airfoil instability noise, assuming tones are created by selective amplification by a feedback loop.
Figure 3.13 Blunt airfoil with vortex shedding.
Figure 3.14 Flow field that develops over an airfoil just prior to stall.
Figure 3.15 Time variation of BTI noise source strength over one revolution of an upwind wind turbine.
Chapter 4: Wind Turbine Sound Power Estimation
Figure 4.1 Overall framework for semi-empirical modelling of wind turbine noise.
Figure 4.2 Wind turbine blade element model.
Figure 4.3 Placement of microphone for determining the sound power level of a wind turbine according to IEC 61400-11 (2012).
Figure 4.4 Typical 1/3-octave power plot obtained using the measurement procedure outlined in IEC 61400-11 (2012). Data from Kaiser-Wilhelm-Koog GmbH (2005).
Figure 4.5 Placement of microphones for determining the sound power level of a wind turbine without having to measure backgound noise.
Chapter 5: Propagation of Noise and Vibration
Figure 5.1 Geometry for a line of point sources.
Figure 5.2 Geometry illustrating reflection of a wave incident on the ground surface.
Figure 5.3 Estimates of the wind shear coefficient for wind speed as a function of surface roughness, based on averaged measurements between 10 and 100 m above the ground (after Irwin (1979)). The exponent is a function of Pasquill stability categories, A–F, (see Table 5.3) and surface roughness.
Figure 5.4 Geometry for a sound ray originating at source, S and arriving at receiver, R.
Figure 5.5 Geometry for calculating the radius of curvature of a sound ray originating at source, S, and arriving at receiver, R, for a source higher than the receiver and for the maximum ray height between the source and receiver.
Figure 5.6 Geometry for calculating the radius of curvature of a sound ray originating at source, S and arriving at receiver, R, for a receiver higher than the source and for the maximum ray height between the source and receiver.
Figure 5.8 Geometry for calculating the radius of curvature of a sound ray originating at source, S and arriving at receiver, R, for a receiver higher than the source and for the maximum ray height
not
between the source and receiver.
Figure 5.9 Geometry illustrating the arrangement for determining and when the source–receiver distance is comparable to the source height.
Figure 5.10 Geometrical parameters for calculating the height and centre of curvature of a curved sound ray beginning at point S and ending at point R.
Figure 5.11 Geometrical parameters for a direct ray from source to receiver, leaving the source at an angle below the horizontal.
Figure 5.12 Excess attenuation due to the ground. The octave band centre frequency (Hz) corresponding to each curve is indicated on the figure.
Figure 5.13 CONCAWE meteorological curves for various octave bands. Categories 1 and 2 correspond to upwind propagation whereas categories 5 and 6 correspond to downwind propagation. (a) 63 Hz, (b) 125 Hz, (c) 250 Hz, (d) 500 Hz, (e) 1000 Hz, (f) 2000 Hz, (g) 4000 Hz.
Figure 5.14 Geometry for sound propagation over a single edge barrier.
Figure 5.15 Diffraction paths (labelled 1 to 4) over a long barrier.
Figure 5.16 Sound attenuation of a semi-infinite screen in free space. If there is a direct line of sight between the source and receiver, is set negative.
Figure 5.17 Parameters used for calculation of the Fresnel number for propagation over a hill or across a valley. In the lower Figure the Fresnel number is negative and the barrier effect does not include the contribution of reflected paths.
Figure 5.18 Geometry for sound propagation over a double edge (or thick) barrier.
Figure 5.19 Path lengths for sound propagation through foliage.
Figure 5.20 Source and receiver heights above the ground and the mean ground plane.
Figure 5.21 Various geometries for determining the path length differences between direct and diffracted rays for a homogeneous atmosphere. In part (e), .
Figure 5.22 Various geometries for determining the path length differences between direct and diffracted rays for a downward-refracting atmosphere. In part (f), is the sum of the curved path lengths, .
Figure 5.23 Geometry for diffraction over single and multiple diffracting edges. For more than one diffracting edge, the ground effect between two adjacent diffracting edges is ignored, as shown in part (b), where only diffraction edge and diffraction edge , are shown.
Figure 5.24 Excess attenuation in 1/3-octave bands due to the ground, for propagation over flat ground, from a source at height 100 m to a receiver at height 2 m downwind (wind speed 8 m/s at 10 m) for various horizontal propagation distances, : (a) grass covered ground; (b) hard ground (water) and for grass-covered ground. Data taken from Søndergaard et al. (2007).
Figure 5.25 Ray path for reflection from a vertical surface: (a) plan view; (b) elevation view.
Figure 5.26 Typical ground profile divided into segments using the method described in Section E.3.
Figure 5.27 Definition of source and receiver heights for the CONCAWE model.
Figure 5.28 Noise reduction measurements for two residences in the vicinity of the Waterloo wind farm. SPL = sound pressure level.
Figure 5.29 Noise reduction measurements for five residences (total of 9 rooms) in Denmark (data from Møller and Pedersen (2011)) and from a number of separate surveys reported by Stephens et al. (1982).
Figure 5.30 Vibration perception threshold in the most sensitive direction.
Chapter 6: Measurement
Figure 6.1 Sound measurement with two-microphone array: (top) cross power spectral density; (bottom) coherence (see Section 2.4.12). SPL, sound pressure level.
Figure 6.2 Regression analysis of against wind speed at hub height, derived using Eq. (5.17) from the measurements at 10-m height, showing acceptable data (left) and an issue with instrumentation noise floor (right). The linear regression fit is to all data in both figures.
Figure 6.3 Regression analysis of against (left) hub-height wind speed derived from measurements at 10 m; (right) measured wind speed at 1.5 m (right). There are currently no wind turbines within 100 km of this location. The regression fit is to all data in both figures.
Figure 6.4 Arithmetic averaging (left) and linear regression analysis in bins of width 1 m/s (right) for against wind speed at hub height, derived from the measurements at 10 m height, are shown as possible alternatives to a standard regression fit. The analyses have been carried out on all data. Data were measured at the same location as for Figure 6.3.
Figure 6.5 Effect of limiting the velocity range (left) and removing outliers (right) on the regression analysis for against wind speed at hub height, derived from the measurements at 10 m height. There is no discernable difference between the regression fits obtained by including and excluding outliers from the analysis. Data were measured at the same location as for Figure 6.3.
Figure 6.6 function in the frequency domain (right) used to approximate typical amplitudes of the blade-pass frequency (1 Hz) and harmonics up to 80 Hz. The time-domain equivalent (left) is obtained by adding the various harmonics in a phase-correlated way (black curve with peaks represented by solid black circles) or in a random way (grey curve with peaks represented by open circles). is the maximum difference between any two vertically aligned solid and open circles.
Figure 6.7
function (right figure) used to approximate typical amplitudes of the blade-pass frequency (1 Hz) and the first twelve harmonics. The time-domain equivalent (left) is obtained by adding the various harmonics in a phase-correlated way (black curve with peaks represented by solid black circles) or in a random way (grey curves with peaks represented by open circles).
is the maximum difference between any two vertically aligned solid and open circles.
Figure 6.8 Measured levels used to approximate typical amplitudes of the blade-pass frequency 0.8 Hz and harmonics in the frequency domain (right) for frequencies up to 80 Hz. The time-domain equivalent (left) is obtained by adding the various harmonics in a phase-correlated way (black curve with peaks represented by solid black circles) or in a random way (grey curve with peaks represented by open circles).
is the maximum difference between any two vertically aligned solid and open circles.
Figure 6.9 Measured levels used to approximate typical amplitudes of the blade-pass frequency and harmonics in the time-domain for the first twelve harmonics. The time-domain equivalent (left) is obtained by adding the various harmonics in a phase-correlated way (black curve with peaks represented by solid black circles) or in a random way (grey curve with peaks represented by open circles). is the maximum difference between any two vertically aligned solid and open circles.
Figure 6.10 Outdoor-to-indoor 1/3-octave band differences between a ground-mounted outdoor microphone and indoor microphone(s), showing the range from measured maximum to minimum as a shaded area and the mean as the data points joined by a solid line. SPL, sound pressure level.
Figure 6.11 method of amplitude modulation and amplitude variation detection.
Figure 6.12 An example of a 3-dB variation in peak-to-trough level occurring in a 2-s period that would be identified as amplitude variation according to the Den Brook condition.
Figure 6.13 Signal envelope obtained by calculating the Hilbert transform.
Figure 6.14 FFT of signal envelope showing a peak at the blade-pass frequency.
Figure 6.15 (a) Sonogram and (b) FFT of the 45-Hz line in the sonogram, representing the variation in in the frequency range, 42.5–47.5 Hz.
Figure 6.16 Raw spectra and integrated spectra obtained using the RES method of AM detection, showing the level of AM, , for A-weighted spectra (left) and unweighted spectra (right).
Figure 6.17 Signals obtained by band-pass filtering: (a) output from the narrowband filter with centre frequency equal to the blade-pass frequency; (b) output from the narrowband filter with centre frequency equal to the first harmonic of the blade-pass frequency; (c) output from the narrowband filter with centre frequency equal to the second harmonic of the blade-pass frequency; (d) sum of curves (a)–(c) compared to the unfiltered signal. Sample rate is 10 samples/s.
Figure 6.18 Definition of onset rate and level difference used in the Nordtest method. OR, onset rate; SPL, sound pressure level.
Figure 6.19 Comparison between the modulation depth obtained using three different metrics and applying the Salford and Fukushima methods described below. Numbering of AM metrics is consistent with Table 6.3, where Metric 1 is represented by the method, Metric 2 is represented by the RES/RUK methods and Metric 3 is represented by the AMWG method.
Figure 6.20 Definition of and used to define modulation depth according to Fukushima et al. (2013)
Figure 6.21 Comparison of the relative values of modulation depth obtained from the three different metrics using data from the Salford and Fukushima design methods as well as field data with extraneous noise filtered out of the analysis. Numbering of AM metrics is consistent with Table 6.3, where Metric 1 is represented by the method, Metric 2 is represented by the RES/RUK methods and Metric 3 is represented by the AMWG method. Each plotted curve represents data of the same type (i.e. the first curve shows a comparison between field data analysed using Metric 1 and 2).
Figure 6.22 Flow chart illustrating tonality assessment process according to IEC 61400-11 (adapted from IEC 61400-11 (2012)).
Figure 6.23 Critical bandwidths proposed in the IEC 61400-11 (2012), ISO1996-2 (2007) and DIN 45681 (2005) standards.
Figure 6.24 Criteria levels used for classification of spectral lines (frequency resolution: 1 Hz). SPL, sound pressure level.
Figure 6.25 Definition of tones, noise pause and noise, where is the tone seek criterion, usually set to 1 dB. In this figure, the local maximum is shown in white and the 6 dB point is shown to illustrate which spectral lines would be considered as tones. Spectral lines corresponding to the boundaries of the noise pause, and , are shaded in grey. SPL, sound pressure level.
Figure 6.26 Narrowband plots corresponding to noise measured 3.3 km from the nearest wind turbine in the Waterloo wind farm during shut-down and operational conditions between 12 midnight and 5am. Frequency resolution is 0.1 Hz. Blade-pass frequency of 0.8 Hz is clearly evident in the plot representing operational conditions. The lower plot is zoomed in with respect to frequency to show tonal peaks with side-bands spaced at the blade-pass frequency, which indicates the presence of AM. SPL, sound pressure level.
Figure 6.27 Sonogram plot using the same data as for Figure 6.26 where shut-down conditions are shown in the upper plot and operational conditions shown in the lower plot. The frequency resolution is = 0.8 Hz and the time resolution is = 0.625 s.
Figure 6.28 Variation over 3 days and 4 nights of , and wind speed/direction (hub height and 1.5 m) for a residence located 3.1 km from the nearest turbine of the Hallett stage 5 wind farm. SPL, sound pressure level.
Figure 6.29 Regression analysis of (top) and (bottom) against wind speed measured at the approximate hub height. Data were measured at a residence located 3.1 km from the nearest turbine of the Hallett stage 5 wind farm during operational conditions. The regression fit is to all data in both figures, but excludes data where the wind speed at 1.5 m is greater than 5 m/s. The regression fit is also shown as a dashed line in the upper Figure for comparison with the line.
Figure 6.30 Regression analysis of (top) and (bottom) against wind speed measured at the approximate hub height during nighttime (in this case 12am–5am). Data were measured at a residence located 3.1 km from the nearest turbine of the Hallett stage 5 wind farm during operational conditions. The regression fit is to all data in both figures, but excludes data where the wind speed at 1.5 m is greater than 5 m/s. The regression fit is also shown as a dashed line in the upper Figure for comparison with the line.
Figure 6.31 Regression analysis of
for daytime and nighttime (12am–5am) against wind speed at the approximate hub height. Data were measured at a residence located 3.1 km from the nearest turbine of the Hallett stage 5 wind farm during operational conditions. The regression fit is to daytime data and nighttime data in the upper and lower figures, respectively.
Figure 6.32 Regression analysis for data divided into four directions, 90 apart. Data were measured at a residence located 3.1 km from the nearest turbine of the Hallett stage 5 wind farm during operational conditions.
Figure 6.33 Arithmetic averaging and linear regression analysis in bins of width 1 m/s for against wind speed measured at the approximate hub height are shown as possible alternatives to a standard regression fit. Data were measured at a residence located 3.1 km from the nearest turbine of the Hallett stage 5 wind farm during operational conditions. The analyses have been carried out on all data.
Figure 6.34 Effect of limiting the hub-height wind speed range (left figure) and removing outliers on the regression analysis (right figure) for against wind speed measured at the approximate hub height. There is no discernible difference between the regression fits obtained by including and excluding outliers from the analysis. Data were measured at a residence located 3.1 km from the nearest turbine of the Hallett stage 5 wind farm during operational conditions.
Figure 6.35 Comparison between 1/3-octave unweighted (circles) and A-weighted (squares) spectra for operational and shut-down conditions when measured approximately 3.3 km from the Waterloo wind farm.
Figure 6.36 Probability density function for overall A-weighted sound pressure levels for turbine-on and off conditions. SPL, sound pressure level.
Figure 6.37 Comparison between hub-height wind speed measurements using data from an ultrasonic anemometer located on the wind turbine generator (WTG) and SODAR data.
Figure 6.38 Waterloo wind farm layout showing the position of the SODAR, which is located on the ridge-top.
Figure 6.39 Velocity profiles for night (12am–5pm) and day, determined using data from cup anemometers (1.5 m and 10 m), nacelle ultrasonic anemometer (161 m) and SODAR (210–310 m). Note that all heights are expressed relative to the elevation of the residence at which the 1.5 m and 10 m measurements were made. The logarithmic curves were determined by adjusting in Eq. (5.30) to obtain the best least squares curve fit when substituted into Eq. (5.17). for daytime and 1.24 for nighttime.
Figure 6.40 Comparison of measured wind speed data with wind speed profiles for nighttime (12 am–5 pm) and daytime, calculated using two different methods with the wind speed at 10 m as the input: Eq. (5.17); and Eq. (5.16), with adjusted to obtain the best fit to the measured data. Note that all heights are expressed relative to the elevation of the residence at which the 1.5 m and 10 m measurements were made.
Figure 6.41 Typical measured wind velocity profiles at nighttime and daytime across the rotor plane, and calculated logarithmic profile according to Eq. (5.17), with . The parameter, , is the number of wind speed profiles used to calculate the average wind speed profile (adapted from Zajamšek et al. (2016)). All heights are relative to the SODAR height.
Figure 6.42 Variation of atmospheric stability over four seasons in 2013.The parameter indicates the total number of samples included in the analysis for each season (Zajamšek et al. 2016).
Figure 6.43 Schematic of open-return wind tunnel.
Figure 6.44 Schematic of closed-return type wind tunnel.
Figure 6.45 Schematic of an open-jet anechoic wind tunnel.
Figure 6.46 Illustration of acoustic refraction through shear layers in an open-jet anechoic wind tunnel.
Figure 6.47 Underbrink array design with , , , rad, and . Each open circle represents a microphone location. Source Prime and Doolan (2013).
Chapter 7: Effects of Wind Farm Noise and Vibration on People
Figure 7.1 Dose–response functions for severe annoyance for wind turbine noise compared to transportation noise. Transportation noise curves from Miedema and Oudshoorn (2001) and wind farm curve from Janssen et al. (2008).
Figure 7.2 Dose response functions for high annoyance in communities found as part of the Health Canada study (Michaud et al., 2016)
Figure 7.3 Illustration of the hearing mechanism.
Figure 7.4 Schematic model of the cochlea (unrolled).
Figure 7.5 (a) Cross-section of the cochlea. (b) Cross section of the cochlear duct.
Figure 7.6 Hearing thresholds and equal loudness contours.
Figure 7.7 Inner and outer hair cell responses, hearing thresholds, environmental infrasound and wind farm infrasound.
Chapter 8: Wind Farm Noise Control
Figure 8.1 Illustration of the construction of an owl wing.
Figure 8.2 Plan view of two wind turbines with possible zones of noise reinforcement.
Figure 8.3 Depiction of a line of turbines as an acoustic line array. Noise from each turbine may reinforce (or not) at specific locations about the wind farm if the phasing between each turbine allows it.
Figure 8.4 Theoretical directivity patterns about the line array of turbines depicted in Figure 8.3, for different separation distances and for each turbine emitting sound at Hz with identical phase.
Figure 8.5 Schematic of a typical single-channel active noise-control system, where represents the variable value at the th time sample and is the estimate of the cancellation-path impulse response.
Figure 8.6 Schematic of a multi-channel active noise-control system, where represents the variable value at the th time sample and is the estimate of the cancellation-path impulse response between the input to source, and the output of error sensor, . LMS=least mean square.
Figure 8.7 Schematic of a finite impulse response filter (tapped delay line) used in an active noise-control (ANC) controller.
Chapter 9: Recommendations for Future Research
Figure 9.1 Error in sound pressure level for an instrument with an electronic noise floor of 18 dBA. The sound pressure level indicated by the instrument is the actual sound pressure level plus the error.
Appendix D: Calculation of Ray Path Distances and Propagation Times for the Nord2000 Model
Figure D.1 Geometrical parameters for a reflected ray from a source to a receiver: (a) source higher than the receiver and the maximum height of the ray path lying between the source and receiver; (b) source higher than the receiver with the maximum height of the ray path lying on the opposite side of the source from the receiver; (c) receiver higher than the source with the maximum height of the ray path lying between the source and receiver; (d) receiver higher than the source with the maximum height of the ray path lying on the opposite side of the receiver from the source.
Figure D.2 Geometrical parameters for a reflected ray from a source to a receiver, with the source higher than the receiver: (a) maximum height of the ray path, both prior to and after reflection, lying between the source and receiver; (b) maximum height of the ray path prior to reflection lying on the opposite side of the source from the receiver and after reflection lying between the source and receiver; (c) maximum height of the ray path prior to reflection lying between the source and receiver and after reflection, lying on the opposite side of the receiver to the source; (d) maximum height of the ray path before reflection lying on the opposite side of the source from the receiver and after reflection, lying on the opposite side of the receiver to the source.
Appendix E: Calculation of Terrain Parameters for the Nord2000 Sound Propagation Model
Figure E.1 Geometrical parameters for a reflected ray from source to receiver
Figure E.2 Typical valley-shaped ground profile, where the individual ground segments are numbered 1–6
Figure E.3 Various types of line segment: (a) concave, where and ; (b) convex, where and ; (c) transition, (neither concave nor convex). The line segments are taken from Figure E.2 and the identifying numbers correspond in each figure.
Figure E.4 Construction for the calculation of (a) and (b) .
Figure E.5 Examples of segmented terrain profiles: (a) approximately flat terrain; (b) valley-shaped terrain; (c) hilly terrain, where the start and end points of each segment are indicated by open circles.
Figure E.6 Ground profile cross section used for the segmentation example
Figure E.7 Illustration of the two most efficient diffraction edges ( and ): (a) terrain with a single diffraction edge above the line of sight between the source and receiver; (b) terrain with multiple diffraction edges, which are all part of the same terrain feature, above the line of sight between the source and receiver; (c) terrain with multiple diffraction edges above the line of sight between the source and receiver, including a double diffraction edge, and ; (d) terrain with diffraction edges below the line of sight between the source and receiver.
Figure E.8 Simplification of a segmented hill with multiple diffraction edges to a hill with two diffraction edges.
Figure E.9 Definition of variables used to calculate the sound pressure at the receiver due to diffraction by a finite-impedance wedge in free space.
Figure E.10 Primary and secondary diffraction edges for a thick barrier with two diffraction edges: (a) diffraction over primary diffraction edge, ; (b) diffraction over secondary diffraction edge, ; (c) diffraction over primary edge, , for a receiver with a direct line of sight to the source.
Figure E.11 Definition of variables used to calculate the sound pressure at the receiver due to diffraction by a thick barrier, in free space, with two diffraction edges, with the primary diffraction edge closest to the receiver: (a) diffraction over the first edge, ; (b) diffraction over the second edge, .
Figure E.12 Definition of variables used to calculate the sound pressure at the receiver due to diffraction over two finite-impedance wedges, in free space, with the primary diffraction edge closest to the receiver: (a) diffraction over the primary wedge; (b) diffraction over the secondary wedge.
Figure E.13 Diffraction over a finite-impedance wedge including the effect of the ground: (a) flat ground; (b) segmented ground profile.
Figure E.14 Diffraction paths (eight) for a double wedge.
Appendix F: Calculation of Fresnel Zone Sizes and Weights
Figure F.1 Definition of the 1-D Fresnel zone for reflection of a ray travelling from the source to the receiver , showing the image source as far below the ground segment (or its extension) as the actual source is above the ground.
Figure F.2 Definition of Fresnel variables for curved rays resulting from a downward-refracting atmosphere.
Figure F.3 Definition of distances and for a specified ground segment under a non-diffracting atmosphere.
Figure F.4 Definition of distances, and for a specified ground segment under a diffracting atmosphere
Figure F.5 Definition of equivalent segment size and orientation to replace a convex terrain segment, showing that the equivalent segment is the projection of the concave segment on the terrain base line or on a line parallel to it: (a) top of equivalent wedge above the terrain base line; (b) top of equivalent wedge below the terrain base line.
Appendix G: Calculation of Diffraction and Ground Effects for the Harmonoise Model
Figure G.1 Double diffraction for the purpose of illustrating the calculation of the diffraction effect: (a) diffraction over the most efficient diffraction edge; (b) diffraction over the second most efficient diffraction edge.
Figure G.2 Definition of parameters used in diffraction effect calculations: (a) screen blocks the line-of-sight between the source and receiver; (b) screen does not block the line-of-sight between the source and receiver.
Figure G.3 Construction of a convex hull for the ground profile between the source, and receiver, . The convex hull is defined by the dotted line passing through and a hull ground segment is that between points and .
Figure G.4 Ground profile with diffraction edges: (a) aegmentation example with a number of diffraction edges, , , and ; (b) illustration of local () coordinate system for segment to .
Figure G.5 (a) Geometry for the transition model example showing secondary source and receiver positions at the top of diffraction edges between which the ground effect is to be calculated; (b) location of the specular reflection point, , for segment 16.
Figure G.6 Intersection with a ground segment of the Fresnel ellipsoid with foci at the image source, , and receiver, : (a) 2-D Fresnel length used for terrain modelling is shown as the intersection of the Fresnel ellipse with the line representing the ground segment (or its extension), shown in the Figure as the thick line; (b) Fresnel ellipse in the plane of the ground segment is shown, with centre at O, major axis length and minor axis length . The ground segment is shown as a thick line extending from to .
List of Tables
Chapter 1: Wind Energy and Noise
Table 1.1 EROI and energy payback times for various energy generation facilities
Table 1.2 Action to be taken for different levels of noise
Table 1.3 1/3-octave band unweighted noise limits () recommended by DEFRA to avoid annoyance
Table 1.4 NPI values for a range of receiver sites
Table 1.5 Community perception of noise and community response as a function of the NPI value of the noise
Table 1.6 Recommendations for community noise limits according to ISO1996-1971
Table 1.7 ISO1996-1971 recommendations for allowable community noise limits
Table 1.8 Noise metrics and threshold limits for Western USA
Table 1.9 Noise metrics and threshold limits for Eastern USA
Table 1.10 Noise metrics and threshold limits for countries outside the USA. is the total height of the turbine (hub height plus blade length) and is the blade length. Wind speeds are at 10 m height
Table 1.11 Octave band noise limits in Illinois () and Oregon ()
Table 1.12 1/3-octave band noise limits in Shawano County (WI) (
). The 70 dB in bands 2–12.5 Hz is for each band in that range
Table 1.13 Allowed wind farm noise levels in three Canadian provinces
Chapter 2: Fundamentals of Acoustics and Frequency Analysis
Table 2.1 Table for combining decibel levels
Table 2.2 Weighting corrections (dB) at 1/3-octave band centre frequencies to be added to unweighted signal
Table 2.3 Preferred octave and 1/3-octave frequency bands
Table 2.4 1/3-octave filter rise times for a 1-dB error.
a
Table 2.5 Properties of the various time weighting functions
Chapter 3: Noise Generation
Table 3.1 Turbulent eddies and their relationship to a typical wind turbine blade
Table 3.2 Typical wind turbine gearbox gear mesh frequencies
Chapter 4: Wind Turbine Sound Power Estimation
Table 4.1 Constants for use in Eq. (4.5)
Chapter 5: Propagation of Noise and Vibration
Table 5.1 Variability in sound level predictions due to meteorological influences, (dB), including both upwind and downwind conditions
Table 5.2 Values of the empirical constant for a neutral (adiabatic) atmosphere (Pasquill stability category D)
Table 5.3 Estimates of roughness length for various ground surface types (Davenport 1960; Wieringa 1980, 1992)
Table 5.4 Alternative estimates of roughness length for various ground surface types
Table 5.5 Source–receiver distance at which more than one reflected ray arrives at the receiver. Receiver height of 1.5 m
Table 5.6 Constants used in the Danish low-frequency noise regulation (2012)
Table 5.7 Daytime incoming solar radiation
Table 5.8 CONCAWE determination of Pasquill stability category from meteorological information
Table 5.9 CONCAWE determination of meteorological category
Table 5.10 95% confidence limits of the CONCAWE model, which is representative of the expected reliability of a single calculation
Table 5.11 Octave-band ground attenuation contributions, and
Table 5.12 Octave band attenuation, due to dense foliage (after ISO9613-2 (1996))
Table 5.13 Estimates of sound absorption coefficient
Table 5.14 Values for the parameter, (not to be confused with -weighting)
Table 5.15 Estimates of the coefficient,
Table 5.16 Estimates of the coefficient,
Table 5.17 Values for the parameter,
Table 5.18 Values for the parameter,
Table 5.19 Interior noise level measurement requirements
Table 5.20 Weighting values to be applied to measured 1/3-octave band vibration levels to calculate the overall vibration level using Eq. (226)
Chapter 6: Measurement
Table 6.1 Critical frequency bands corresponding to integer and half-integer Bark values
Table 6.2 Metrics used for detection of amplitude modulation, amplitude variation and impulsiveness
Table 6.3 Advantages and disadvantages of time-series, frequency domain and hybrid methods (mainly from AMWG (2015))
Table 6.4 Logarithmic subtraction of turbine-off levels from turbine-on levels to obtain turbine-only sound pressure levels in 1 dBA bins
Table 6.5 Turbine on probabilities for overall A-weighted sound pressure levels between 34 and 41 dB
Table 6.6 Turbine off probabilities for overall A-weighted sound pressure levels between 14 and 40 dB
Table 6.7 Probability of turbine-only overall A-weighted sound pressure levels for various combinations of turbine ON/OFF levels
Table 6.8 Tolerance limits including maximum expanded uncertainties of measurement for sound level meters with A-, C- or Z-weighted filters for nominal frequencies from 10 to 160 Hz
Table 6.9 Summary of some of the relevant sources of error for noise measured at frequencies 1000 Hz
Chapter 7: Effects of Wind Farm Noise and Vibration on People
Table 7.1 Corrected weightings at 1/3-octave band centre frequencies to include the effect of transmission from outside to inside a residence (after Kelley (1987))
Table 7.2 Interior annoyance level criteria as a function of noise type
Chapter 8: Wind Farm Noise Control
Table 8.1 Recommended 1/3-octave white-noise masking spectra for an A-weighted level of 30 dBA
Chapter 9: Recommendations for Future Research
Table 9.1 Japan Ministry of Environment criteria for low-frequency noise (JMEF 2004)
Appendix C: Ground Reflection Coefficient Calculations
Table C.1 Flow resistivities measured for some common ground surfaces
Table C.2 Flow resistivities for some common ground surface types (to be used with the ISO9613-2, NMPB-2008, NORD2000 and Harmonoise propagation models)
Appendix E: Calculation of Terrain Parameters for the Nord2000 Sound Propagation Model
Table E.1 Coefficients and as a function of , to be used in Eqs (E.40) and (E.41)
Wiley Series in Acoustics, Noise and Vibration:
Wind Farm Noise
Hansen
February 2017
The Effects of Sound on People
Cowan
May 2016
Engineering Vibroacoustic Analysis: Methods and Applications
Hambric et al
April 2016
Formulas for Dynamics, Vibration and Acoustics
Blevins
November 2015
Wind Farm Noise: Measurement, Assessment and Control
Colin H. Hansen
School of Mechanical Engineering University of Adelaide Australia
Con J. Doolan
School of Mechanical and Manufacturing Engineering University of New South Wales Australia
Kristy L. Hansen
School of Computer Science, Engineering and Mathematics Flinders University Australia
This edition first published 2017
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Library of Congress Cataloging-in-Publication Data
Names: Hansen, Colin H., 1951- author. | Doolan, Con J., author. | Hansen, Kristy L., author.
Title: Wind farm noise : measurement, assessment and control / Colin H. Hansen, Con J. Doolan, Kristy L. Hansen.
Description: Hoboken : John Wiley & Sons Inc., [2017] | Includes bibliographical references and index.
Identifiers: LCCN 2016036077| ISBN 9781118826065 (cloth) | ISBN 9781118826126 (epub) | ISBN 9781118826119 (Adobe PDF)
Subjects: LCSH: Wind power plants–Noise.
Classification: LCC TK1541 .H26 2017 | DDC 621.31/2136–dc23 LC record available at https://lccn.loc.gov/2016036077
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If we knew what it was we were doing, it wouldn't be called research, would it?
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Wiley Series in Acoustics, Noise and Vibration
This book series will embrace a wide spectrum of acoustics, noise and vibration topics from theoretical foundations to real world applications. Individual volumes will range from specialist works of science to advanced undergraduate and graduate student texts. Books in the series will review scientific principles of acoustics, describe special research studies and discuss solutions for noise and vibration problems in communities, industry and transportation.
The first books in the series include those on Biomedical Ultrasound; Effects of Sound on People, Engineering Acoustics, Noise and Vibration Control, Environmental Noise Management; Sound Intensity and Windfarm Noise. Books on a wide variety of related topics.
The books I edited for Wiley, the Encyclopedia of Acoustics (1997), the Handbook of Acoustics (1998) and the Handbook of Noise and Vibration Control (2007) included over 400 chapters written by different authors. Each author had to restrict their chapter length on their special topics to no more than about 10 pages. The books in the current series will allow authors to provide much more in-depth coverage of their topic.
The series will be of interest to senior undergraduate and graduate students, consultants, and researchers in acoustics, noise and vibration and in particular those involved in engineering and scientific fields, including, aerospace, automotive, biomedical, civil/structural, electrical, environmental, industrial, materials, naval architecture and mechanical systems. In addition the books will be of interest to practitioners and researchers in fields such as audiology, architecture, the environment, physics, signal processing and speech.
Malcolm J. CrockerSeries Editor
Preface
Wind farm noise has polarised communities and is featured on numerous web sites that either dismiss its effects on people as a nocebo effect or as something in their imagination. There are just as many other web sites that claim wind farm noise has led to serious medical problems in some people and that infrasound generated by wind farms can have far-reaching consequences for the health of people who are exposed. These web sites can be found easily by typing ‘wind farm noise’ into any internet search engine.
Our intention when writing this book has been to cover all aspects of wind farm noise, including how it is generated, how it propagates, how it is assessed, how it is regulated and what effects it has on people living in the vicinity of wind turbines. Where aspects of wind farm noise are controversial, we have presented what we believe to be an unbiased assessment of the facts. None of the three authors have ever worked for the wind farm industry nor have they been members of any anti-wind-farm organisation. Only the first author has appeared as an expert witness, in a 2010 court proceedings concerned with a wind farm development. This was his only involvement in court proceedings and it was in the capacity of being asked to critique a report prepared by an acoustical consultant for a wind farm operator.
The first two authors have been chief investigators on a number of research projects, funded by the Australian Research Council, on aerodynamic noise generation and the impact of wind farm noise on rural communities. The first author has also spent over 40 years teaching, researching and consulting in acoustics and noise control. The second author has spent nearly 20 years working in the area of aerospace engineering, with a strong focus on aeroacoustics: the science of how objects like rotor blades create sound. Following completion of a PhD in fluid mechanics, the third author has spend the past four years measuring and analysing wind farm noise.
