Research on Noise Characteristics and Control Schemes for 750kV High Voltage Substation
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The operating electrical devices, such as reactors and transformers, especially in ultrahigh voltage level of substations, are constantly emitting noise, which inevitably brings negative effect on the ambient environment and people. With an increasing number of high voltage substations are under construction, noise emission issues are grabbing the public attention in recent years. 750 kV substation, a very typical high voltage level of substation, is taken as the research object in this paper. The transformer, reactor and the corona noise of lines and metal fittings, as the main noise sources in substation, are measured and analyzed respectively. Sound signal processing array technique is adopted and applied to help positioning the corona noise and the noise characteristic is accordingly obtained by beam forming algorithm. On basis of the collected noise source data, the acoustic field model of the whole 750 kV substation could be established in SoundPLAN software and the noise distribution are predicted. To improve the sound environment quality around the substation, different noise control schemes are put forward and the effect of these approaches are verified and compared through the simulation in SoundPLAN. Several good suggestions are given and it could be very helpful for the early stages of planning and designing of substations in order to reduce the potential noise problems.Keywords:
Ambient noise level
High Voltage
The Marine Strategy Framework Directive imposes to European governments to monitor ambient noise. There are multiple ways of monitoring the ambient noise. Although certainly economical considerations have to be taken into considerations, there is a need to discuss the representativeness of ambient noise measurement by the only means of hydrophones. A hydrophone will only give a local and punctual knowledge. As long as the measurement is not contaminated with self-noise, mechanical noise from the mooring itself or the water flow around the sensor, measurement present the great advantage of providing a ground truth. However, for ambient noise being stochastic by essence, masking effects between numbers of anthropic sources are likely to occur for significant period of times. Hydrophones therefore measure the closest noise events. An ambient noise experiment done in the western part of the British Channel in 2010 has demonstrated such effects, and serves questioning the representativeness of noise monitoring exclusively based on measurement. The choice of the metric and the influence of the geographical configuration of the monitoring scheme on noise characterization will be discussed. Coupling measurement with modeling is foreseen as a solution to bring more representativeness to ocean noise assessment.
Ambient noise level
Environmental Noise
Hydrophone
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High Voltage
High tech
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Ambient noise interferometry is a passive acoustic technique for environment characterization. The technique uses coherent ambient sound to approximate the Green’s function between two sensors. It has previously been used in ocean acoustics to passively estimate water temperature, sound-speed structure, and mode shapes as well as for sensor localization. Since this technique utilizes the ambient noise field, whose characteristics are often unknown, understanding the effects of non-isotropic ambient sound is important for ambient noise interferometry. In this talk, an overview of the theoretical literature for noise interferometry will be presented with a specific emphasis on the effects of non-isotropic ocean noise source distributions. Additionally, simulations that explore the emergence of the Green’s function will be presented. Specifically, sound source distributions and environmental parameters such as sound speed profile will be explored. Lastly, the implications of these works on the possibilities and limitations of ambient noise interferometry will be discussed. [Work supported by the ONR.]
Ambient noise level
Seismic interferometry
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Cross-correlation of ambient noise is an effective approach to extract seismic responses between two stations using seismic interferometry. Since we frequently calculate the cross-correlation of the ambient noise assuming homogeneous distribution of ambient noise sources, heterogeneous distribution of the ambient noise sources would interfere in constructing seismic responses in the calculation of the cross-correlation. In this study, we identified the ambient noise sources recorded in a dense seismic array and utilized the information for better subsurface imaging. The seismic array was composed of 50 stations installed in a 480 m ×350 m area in the Itoshima Peninsula, Japan. By analyzing direction of incoming ambient noise, we found that most of ambient noise was generated by traffic from the nearby street. The traffic noise generated surface waves in lower frequencies (< ~10 Hz) and Pwaves in higher frequencies (> ~20 Hz). We also identified high frequency surface (or air) waves generated by a point source at ~60 Hz. This localized noise could be derived from the renovation work because the location of the source was estimated around the renovation site. We then estimated low- and high-frequency surface wave velocities between each station pair. Although we estimated the surface wave velocities in the limited azimuth between the stations due to the localized noise distribution, we estimated reliable surface wave velocities by considering the noise heterogeneity. High resolution maps of the surface wave velocities were tomographically constructed from the surface wave velocities between the station pairs. Thus, identifying the sources of the ambient noise acquired with dense seismic arrays is effective to improve the ability of ambient noise data to image subsurface structures. It also contributes to the design of seismic arrays in further ambient noise surveys.
Characterization
Ambient noise level
Peninsula
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An understanding of the characteristics and nature of the ambient noise is fundamental to the design of long-range submarine detection systems. During the summer of 1959 a series of deep-ocean ambient noise measurements were made with a 10-element vertical hydrophone array suspended to a depth of 500 fathoms in 2000-fathom water. Measurements were made over the frequency range of 5 to 25 cps. All data were recorded on magnetic tape and returned to the laboratory for analysis. The objectives of the measurements were to determine the spectral nature of the ambient noise and any special properties such as directionality that the ambient noise might have. By use of a magnet drum delay line, the array was steered in a vertical sense about the center of the array. The intensity and frequency spectrum of the beams was recorded. Broadband spectrum analysis was made, and both frequency and power spectrum plots were obtained of the ambient. A considerable amount of biological noise was recorded, and some classification of these signals was made. This paper describes the method and instrumentation used in recording the raw data and a description of the data analysis techniques. The results of the data analysis program are then discussed in detail.
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Hydrophone
Instrumentation
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Ambient noise tomography (ANT) has been widely used to image crust and upmost mantle structures. ANT assumes that sources of ambient noise are diffuse and evenly distributed in space and the energy of different modes is equipartitioned. At present, the sources of the primary and the secondary microseisms are well studied, but there are only a few on the studies of long-period ambient noise sources. In this study, we study the effects of large earthquake signals on the recovery of surface waves from seismic ambient noise data recorded by seismic stations from the US permanent networks and Global Seismographic Network (GSN). Our results show that large earthquake signals play an important role on the recovery of long-period surface waves from ambient noise cross-correlation functions. Our results are consistent with previous studies that suggest the contribution of earthquake signals to the recovery of surface waves from cross-correlations of ambient noise is dominant at periods larger than 20–40 s.
Ambient noise level
Seismic Noise
Microseism
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Measured sound pressure time series in shallow and deep-water ocean environments are used to investigate the character of wind-generated noise over a range of wind speed of 2–40 knots and a frequency band of 10–3,000 Hz. In 2006, acoustic data were collected during tropical storm Ernesto off the New Jersey continental shelf in shallow (70 m) water. Ambient noise from these data is compared to deep-water measurements at several locations in the Northwest and the Northeast Pacific. The results also are compared to previously reported measurements by [Kuperman and Ferla (1985)], [Wenz (1962)], and others. The analysis includes a technique for separating background shipping noise from the wind-induced component of ambient noise. The system electronic noise floor and other extraneous sources of noise are evaluated to assure that the ambient noise measurements are not corrupted. Physical mechanisms examined include a wind-saturation effect that limits the ability to acoustically monitor distant storms and the effect of shallow water propagation on the character of wind noise. The identification of the distant shipping part of the spectrum allows for inferences to be made on the low frequency part of the ambient noise spectrum. [Work supported by ONR.]
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Ambient noise level
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Abstract : Contents: PROCESSING TECHNIQUES--A method of estimating the influence of ship's noise on ambient noise measurements; Optimal detection and tracking of acoustical noise sources in a time-varying environment; Influence of background- noise spatial coherence on high-resolution passive method; Performance of three averaging methods for various distributions; Is power averaging the best estimator for undersea acoustic data? MODELLING: DEVELOPMENT AND USE--A parametric examination of some properties of the low-frequency ambient-noise field; Detection models and target-information processing; The prediction of temporal statistics of directional ambient shipping noise; Site and frequency dependence of ambient noise in the north eastern Pacific Ocean; ACOUSTIC PROPAGATION EFFECTS--Site dependence of wind-dominated ambient noise in shallow water; Effects of topographic blockage and ocean boundaries on low-frequency noise fields; The seamount as a noise barrier.
Ambient noise level
Underwater Acoustics
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