scholarly journals Prediction of noise from wind turbines: theoretical and experimental study

2018 ◽  
pp. 34-41 ◽  
Author(s):  
Carlos Alberto Echeverri-Londoño ◽  
Alice Elizabeth González Fernández
Keyword(s):  
Wind Turbines ◽  
Wind Farm ◽  
Sound Pressure ◽  
Prediction Method ◽  
Wide Band ◽  
Propagation Models ◽  
Low Frequencies ◽  
High Frequencies ◽  
Wind Speeds ◽  
Sound Pressure Levels

Several noise propagation models used to calculate the noise produced by wind turbines have been reported. However, these models do not accurately predict sound pressure levels. Most of them have been developed to estimate the noise produced by industries, in which wind speeds are less than 5 m/s, and conditions favor its spread. To date, very few models can be applied to evaluate the propagation of sound from wind turbines and most of these yield inaccurate results. This study presents a comparison between noise levels that were estimated using the prediction method established in ISO 9613 Part 2 and measured levels of noise from wind turbines that are part of a wind farm currently in operation. Differences of up to 56.5 dBZ, with a median of 29.6 dBZ, were found between the estimated sound pressure levels and measured levels. The residual sound pressure levels given by standard ISO 9613 Part 2 for the wind turbines is larger for high frequencies than those for low frequencies. When the wide band equivalent continuous sound pressure level is expressed in dBA, the residual varies between −4.4 dBA and 37.7 dBA, with a median of 20.5 dBA.

Directional sound processing and interaural sound transmission in a small and a large grasshopper

1995 ◽  
Vol 198 (9) ◽  
pp. 1817-1827 ◽  
Author(s):  
A Michelsen ◽  
K Rohrseitz
Keyword(s):  
Outer Surface ◽  
Sound Pressure ◽  
Schistocerca Gregaria ◽  
Sound Transmission ◽  
Directional Hearing ◽  
Sound Processing ◽  
Low Frequencies ◽  
High Frequencies ◽  
Physical Mechanisms ◽  
Chorthippus Biguttulus

Physical mechanisms involved in directional hearing are investigated in two species of short-horned grasshoppers that differ in body length by a factor of 3­4. The directional cues (the effects of the direction of sound incidence on the amplitude and phase angle of the sounds at the ears) are more pronounced in the larger animal, but the scaling is not simple. At high frequencies (10­20 kHz), the sound pressures at the ears of the larger species (Schistocerca gregaria) differ sufficiently to provide a useful directionality. In contrast, at low frequencies (3­5 kHz), the ears must be acoustically coupled and work as pressure difference receivers. At 3­5 kHz, the interaural sound transmission is approximately 0.5 (that is, when a tympanum is driven by a sound pressure of unit amplitude at its outer surface, the tympanum of the opposite ear receives a sound pressure with an amplitude of 0.5 through the interaural pathway). The interaural transmission decreases with frequency, and above 10 kHz it is only 0.1­0.2. It still has a significant effect on the directionality, however, because the directional cues are large. In the smaller species (Chorthippus biguttulus), the interaural sound transmission is also around 0.5 at 5 kHz, but the directionality is poor. The reason for this is not the modest directional cues, but rather the fact that the transmitted sound is not sufficiently delayed for the ear to exploit the directional cues. Above 7 kHz, the transmission increases to approximately 0.8 and the transmission delay increases; this allows the ear to become more directional, despite the still modest directional cues.

Environmental noise-induced cardiovascular responses during sleep

SLEEP ◽  
2021 ◽  
Author(s):  
Bastien Lechat ◽  
Hannah Scott ◽  
Felix Decup ◽  
Kristy L Hansen ◽  
Gorica Micic ◽  
...  
Keyword(s):  
Wind Farm ◽  
Wave Amplitude ◽  
Sound Pressure ◽  
Noise Exposure ◽  
Pulse Wave ◽  
Traffic Noise ◽  
Cardiovascular Responses ◽  
Environmental Noise ◽  
Pulse Wave Amplitude ◽  
Sound Pressure Levels

Abstract Study Objectives This study was designed to test the utility of cardiovascular responses as markers of potentially different environmental noise disruption effects of wind farm compared to traffic noise exposure during sleep. Methods Twenty participants underwent polysomnography. In random order, and at six sound pressure levels from 33 dBA to 48 dBA in 3 dB increments, three types of wind farm and two types of road traffic noise recordings of 20-sec duration were played during established N2 or deeper sleep, each separated by 20 seconds without noise. Each noise sequence also included a no-noise control. Electrocardiogram and finger pulse oximeter recorded pulse wave amplitude changes from the pre-noise onset baseline following each noise exposure and were assessed algorithmically to quantify the magnitude of heart rate and finger vasoconstriction responses to noise exposure. Results Higher sound pressure levels were more likely to induce drops in pulse wave amplitude. Sound pressure levels as low as 39 dBA evoked a pulse wave amplitude response (Odds ratio [95% confidence interval]; 1.52 [1.15, 2.02]). Wind farm noise with amplitude modulation was less likely to evoke a pulse wave amplitude response than the other noise types, but warrants cautious interpretation given low numbers of replications within each noise type. Conclusion These preliminary data support that drops in pulse wave amplitude are a particularly sensitive marker of noise-induced cardiovascular responses during. Larger trials are clearly warranted to further assess relationships between recurrent cardiovascular activation responses to environmental noise and potential long-term health effects.

ALL-DC Offshore Wind Farm With Series-Connected Wind Turbines to Overcome Unequal Wind Speeds

2019 ◽  
Vol 34 (2) ◽  
pp. 1370-1381 ◽  
Author(s):  
Fei Rong ◽  
Gongping Wu ◽  
Xing Li ◽  
Shoudao Huang ◽  
Bin Zhou
Keyword(s):  
Wind Turbines ◽  
Wind Farm ◽  
Offshore Wind ◽  
Offshore Wind Farm ◽  
Wind Speeds

scholarly journals Results from a wake-steering experiment at a commercial wind plant: investigating the wind speed dependence of wake-steering performance

2021 ◽  
Vol 6 (6) ◽  
pp. 1427-1453
Author(s):  
Eric Simley ◽  
Paul Fleming ◽  
Nicolas Girard ◽  
Lucas Alloin ◽  
Emma Godefroy ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Direction ◽  
Wind Farm ◽  
Poor Performance ◽  
Power Production ◽  
Wind Rose ◽  
Wind Speeds ◽  
Variability Model

Abstract. Wake steering is a wind farm control strategy in which upstream wind turbines are misaligned with the wind to redirect their wakes away from downstream turbines, thereby increasing the net wind plant power production and reducing fatigue loads generated by wake turbulence. In this paper, we present results from a wake-steering experiment at a commercial wind plant involving two wind turbines spaced 3.7 rotor diameters apart. During the 3-month experiment period, we estimate that wake steering reduced wake losses by 5.6 % for the wind direction sector investigated. After applying a long-term correction based on the site wind rose, the reduction in wake losses increases to 9.3 %. As a function of wind speed, we find large energy improvements near cut-in wind speed, where wake steering can prevent the downstream wind turbine from shutting down. Yet for wind speeds between 6–8 m/s, we observe little change in performance with wake steering. However, wake steering was found to improve energy production significantly for below-rated wind speeds from 8–12 m/s. By measuring the relationship between yaw misalignment and power production using a nacelle lidar, we attribute much of the improvement in wake-steering performance at higher wind speeds to a significant reduction in the power loss of the upstream turbine as wind speed increases. Additionally, we find higher wind direction variability at lower wind speeds, which contributes to poor performance in the 6–8 m/s wind speed bin because of slow yaw controller dynamics. Further, we compare the measured performance of wake steering to predictions using the FLORIS (FLOw Redirection and Induction in Steady State) wind farm control tool coupled with a wind direction variability model. Although the achieved yaw offsets at the upstream wind turbine fall short of the intended yaw offsets, we find that they are predicted well by the wind direction variability model. When incorporating the expected yaw offsets, estimates of the energy improvement from wake steering using FLORIS closely match the experimental results.

scholarly journals Results from a Wake Steering Experiment at a Commercial Wind Plant: Investigating the Wind Speed Dependence of Wake Steering Performance

2021 ◽  
Author(s):  
Eric Simley ◽  
Paul Fleming ◽  
Nicolas Girard ◽  
Lucas Alloin ◽  
Emma Godefroy ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Direction ◽  
Wind Farm ◽  
Poor Performance ◽  
Power Production ◽  
Wind Rose ◽  
Wind Speeds ◽  
Variability Model

Abstract. Wake steering is a wind farm control strategy in which upstream wind turbines are misaligned with the wind to redirect their wakes away from downstream turbines, thereby increasing the net wind plant power production and reducing fatigue loads generated by wake turbulence. In this paper, we present results from a wake steering experiment at a commercial wind plant involving two wind turbines spaced 3.7 rotor diameters apart. During the three-month experiment period, we estimate that wake steering reduced wake losses by 5.7 % for the wind direction sector investigated. After applying a long-term correction based on the site wind rose, the reduction in wake losses increases to 9.8 %. As a function of wind speed, we find large energy improvements near cut-in wind speed, where wake steering can prevent the downstream wind turbine from shutting down. Yet for wind speeds between 6–8 m/s, we observe little change in performance with wake steering. However, wake steering was found to improve energy production significantly for below-rated wind speeds from 8–12 m/s. By measuring the relationship between yaw misalignment and power production using a nacelle lidar, we attribute much of the improvement in wake steering performance at higher wind speeds to a significant reduction in the power loss of the upstream turbine as wind speed increases. Additionally, we find higher wind direction variability at lower wind speeds, which contributes to poor performance in the 6–8 m/s wind speed bin because of slow yaw controller dynamics. Further, we compare the measured performance of wake steering to predictions using the FLORIS (FLOw Redirection and Induction in Steady State) wind farm control tool coupled with a wind direction variability model. Although the achieved yaw offsets at the upstream wind turbine fall short of the intended yaw offsets, we find that they are predicted well by the wind direction variability model. When incorporating the predicted achieved yaw offsets, estimates of the energy improvement from wake steering using FLORIS closely match the experimental results.

The Response of the Swim Bladder of the Goldfish (Carassius Auratus) to Acoustic Stimuli

1974 ◽  
Vol 60 (2) ◽  
pp. 295-304
Author(s):  
ARTHUR N. POPPER
Keyword(s):  
Sound Pressure ◽  
Sound Production ◽  
Broad Band ◽  
Coupled System ◽  
Wide Band ◽  
Limiting Factor ◽  
Swim Bladder ◽  
Phase Measurements ◽  
Goldfish Carassius Auratus ◽  
Sound Pressure Levels

1. Sound-pressure levels were measured in the swim bladder of the goldfish using a probe microphone. Measurements of pressure and phase were made relative to the sounds immediately outside of the fish. 2. Results showed that the response of the swim bladder is flat from 50 to 2000 Hz with sound-pressure levels within the swim bladder about 4 or 5 dB below the sound pressure outside of the fish. 3. Phase measurements in the swim bladder were not significantly different from those made outside of the fish. 4. The data indicate that there is little loss between the water and the inside of the fish, indicating that the swim bladder acts to closely couple the fish to the water. This has significant implications since a poorly coupled system would severely limit detection capabilities for sounds and greatly increase the energy needed to get sound into the water during sound production. 5. The fact that there is a flat response over the major portion of the range of auditory sensitivity in goldfish indicates that the swim bladder is most probably not a limiting factor in acoustic sensitivity, at least below 2000 Hz. In addition, the swim bladder, as a poorly tuned or untuned system, does not selectively affect signals around what would be the resonance frequency in a more sharply tuned system. 6. The poor tuning of the swim bladder is important for communication since a portion of the communicatively significant sounds for fishes are broad-band, rapidly repeating pulses. A sharply tuned system cannot respond to these signals while a poorly tuned system is suitable for wide-band and time-locked reception.

Installation Vessel and Method for Offshore Wind Turbine in Ultra-Shallow Water

2010 ◽  
Author(s):  
Huiqu Fan ◽  
Jinbao Lin ◽  
Qingsong Shi
Keyword(s):  
Wind Turbine ◽  
Shallow Water ◽  
Wind Turbines ◽  
Wind Farm ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wind Speeds ◽  
Total Investment ◽  
Key Issues ◽  
Turbine Installation

Compared to onshore wind turbines, offshore wind turbines take advantage of wind speeds which are more constant and stronger than those on land. Since many large electricity load centers are located near coastline in China, larger wind turbines can be installed closer to these areas to supply energy in a more economical way. Wind turbine transportation and installation are key issues for offshore wind farm construction, especially for large size turbine installation in ultra-shallow water like intertidal zone with water depth less than 5m. The traditional installation vessels with large design drafts are likely to be trapped in shallow water zones. It is usually impossible to carry out turbine installation in shallow water. This paper presents a set of innovative installation vessel concept and corresponding methods for ultra-shallow water zone include ultra-shallow draft crane vessel and ultra-shallow draft barge. The main purpose is to simplify the installation procedures and reduce total investment.

scholarly journals Frequencies Rotation at High Sound Pressure Levels Toward Low Frequencies

2020 ◽  
Vol 54 (4) ◽  
pp. 237-246
Author(s):  
Hadi Negahdari ◽  
Sirus Javadpour ◽  
Faramarz Moattar
Keyword(s):  
Sound Pressure ◽  
Low Frequencies ◽  
Sound Pressure Levels ◽  
High Sound

scholarly journals An Analysis of Wind Power Generation on the Electric Transmission System of Southern Vietnam

2021 ◽  
Vol 16 ◽  
pp. 204-212
Author(s):  
Minh-Hoa Nguyen ◽  
Van-Tan Tran ◽  
Tan-Hung Pham ◽  
Thanh-Luu Cao
Keyword(s):  
Power Generation ◽  
Power Systems ◽  
Power System ◽  
Wind Energy ◽  
Wind Turbines ◽  
Wind Farm ◽  
Wind Farms ◽  
Wind Speeds ◽  
Southern Vietnam ◽  
Three Phase

Renewable energy is an emerging candidate in power generation for the compensation of the exhausted fossil fuel, in which wind energy plays an important role. However, how wind farms impact existing power systems has still been a subject on which many researchers are studying. This study has analyzed and evaluated the four wind farms consisting of Ca-Mau (300 MW), Bac-Lieu (99 MW), Soc-Trang (100 MW) and Tra-Vinh (33 MW) located in Southern Vietnam via using the commercial package, WAsP software. Ca-Mau wind farm has the highest planned rated capacity with 51.7% among the wind farms. Each wind farm is built from three different types of wind turbines (1 MW, 2 MW and 3 MW). The estimation has shown that all of the wind farms could produce 2,265 GWh annually, and the 3-MW wind turbines are the most efficient and give the smallest losses for producing wind energy. The wind farms, with respect to environmentally friendly aspects, could avoid 978,544 tCO2 emitted to the environment annually. Additionally, the ETAP program has also been applied to simulate the effects of the proposed wind farms on the national power system including the disturbances from wind speeds, three-phase bus faults, tripping off wind farms and three-phase line faults on the power system. The results show that the wind farms are only slightly impacted.

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