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A distribuição generalizada de valores extremos no estudo da velocidade máxima do vento em Piracicaba, SP.; The generalized extreme value distribution to study maximum wind speed in Piracicaba, SP.

Bautista, Ezequiel Abraham López
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 29/05/2002 PT
Relevância na Pesquisa
36.21%
A teoria dos valores extremos desempenha um papel fundamental na modelagem de eventos associados a probabilidades muito pequenas ou eventos raros. Os modelos probabilísticos baseados nesta teoria visam predizer, a partir de um conjunto de valores máximos de um processo ambiental registrado num período relativamente curto (30 anos, por exemplo), os valores máximos esperados num período maior de tempo (50, 100 ou mais anos), que para o caso específico dos ventos, são de grande utilidade no planejamento de estruturas civis. Este trabalho consistiu no ajuste da distribuição generalizada de valores extremos (GVE), que inclui como casos particulares, as distribuições Gumbel, Fréchet e de Weibull (definidas na teoria dos valores extremos), aos dados de velocidade máxima mensal de ventos registrados durante um período de 43 anos (1956 a 1971 e 1974 a 2000) na estação agrometeorológica da Escola Superior de Agricultura "Luiz de Queiroz" em Piracicaba, Estado de São Paulo. Para a estimação dos parâmetros dessa distribuição, foi utilizado o método da máxima verossimilhança. O ajuste aos dados foi avaliado através dos gráficos quantil-quantil e do teste de Kolmogorov-Smirnov. A partir do ajuste inicial da distribuição GVE...

A distribuição generalizada de Pareto e mistura de distribuições de Gumbel no estudo da vazão e da velocidade máxima do vento em Piracicaba, SP; The generalized Pareto distribution and Gumbel mixture to study flow and maximum wind speed in Piracicaba, SP

Silva, Renato Rodrigues
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 10/10/2008 PT
Relevância na Pesquisa
36.21%
A teoria dos valores extremos é um tópico da probabilidade que descreve a distribuição assintótica das estatísticas de ordem, tais como máximos ou mínimos, de uma seqüência de variáveis aleatórias que seguem uma função de distribuição F normalmente desconhecida. Descreve, ainda, a distribuição assintótica dos excessos acima de um valor limiar de um ou mais termos dessa seqüência. Dessa forma, as metodologias padrões utilizada neste contexto consistem no ajuste da distribuição generalizada dos valores extremos a uma série de máximos anuais ou no ajuste da distribuição generalizada de Pareto a uma série de dados compostas somente de observações excedentes de um valor limiar. No entanto, segundo Coles et al. (2003), há uma crescente insatisfação com o desempenho destes modelos padrões para predição de eventos extremos causada, possivelmente, por pressuposições não atendidas como a de independência das observações ou pelo fato de que os mesmos não sejam recomendados para serem utilizados em algumas situações específicas como por exemplo e quando observações de máximos anuais compostas por duas ou mais populações independentes de eventos extremos sendo que a primeira descreve eventos menos freqüentes e de maior magnitude e a segunda descreve eventos mais freqüentes e de menor magnitude. Então...

Estudo dos efeitos de variações do vento no sistema de ressurgência ao longo da costa peruana através da análise de dados e modelagem numérica; Study of the wind variation effects in the upwelling system along the Peruvian Coast through data analysis and numerical modeling

Aguirre, Enrique Eduardo Lizardo Huaringa
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 06/07/2007 PT
Relevância na Pesquisa
36.27%
O presente trabalho teve como finalidade estudar os efeitos das variações do vento resultantes de ocorrências do fenômeno El Niño-Southern Oscillation (ENSO) nos padrões da circulação superficial ao longo da costa peruana, através da análise de dados observados e de modelagem numérica. É enfocado o período 1991-2000, quando ocorreram fortes eventos La Niña (1996-97, 1998-2000) e El Niño (1997- 98). Esses eventos tiveram fortes impactos em escala global mas muito pouco se sabe sobre os impactos locais na estrutura da termoclina e no ciclo da dinâmica de Ekman ao longo da costa peruana. Os dados analisados no presente estudo foram dados coletados em duas radiais ao longo das latitudes 5 S e 15 S. O modelo oceânico utilizado foi o Modelo da Universidade de Princeton (Princeton Ocean Model-POM). As simulações numéricas foram forçadas com produtos de vento relativos ao período 1991-2000. Essas simulações reproduziram satisfatoriamente os padrões médios da circulação na região de estudo, confirmando que nas áreas próximas da costa o vento é o principal mecanismo gerador de ressurgência ou subsidência. Os resultados mostraram que durante a ocorrência do forte evento El Niño 1997-1998, nas radiais de 5 S e 15 S...

Wind risk assessment in urban environments: the case of falling trees during windstorm events in Lisbon

Lopes, António; Oliveira, Sandra; Fragoso, Marcelo; Andrade, José; Pedro, P
Fonte: Springer Science+Business media B.V. Publicador: Springer Science+Business media B.V.
Tipo: Parte de Livro
POR
Relevância na Pesquisa
36.27%
Trees bring many benefits to the urban environment. However, they may also cause hazards to human population, being the major causes of injuries and infrastructural damage during strong wind events. In the city of Lisbon, strong winds rather frequently result in tree falls, depending on the season and meteorological conditions. This paper presents a methodology to analyse tree damage due to strong wind events in urban environments. Each occurrence has been recorded by the Lisbon Fire Brigade and Rescue Services (Regimento de Sapadores Bombeiros de Lisboa - RSBL). Information provided by RSBL relating to the period of 1990-2005 was considered along with hourly wind speed and direction, species, fitossanitary conditions and urban parameters. To ensure that the fallen trees were caused by strong winds, only days with three or more occurrences of fallen trees were selected. It was found that in summer, northerly winds are responsible for 11% of tree falls, with winds from other directions (west, southwest and south) responsible for 5%. From autumn to spring, perturbed weather conditions originating from the west, southwest and south are responsible for 84% of fallen trees. The majority of tree falls occurred when wind speed surpassed 7 m/s in the six hours prior to their fall. Some recommendations to the Civil Protection Agency and the Fire Department are presented to improve the mission of collecting information. This research is a contribution to the assessment of wind risk in Lisbon.

Wind Risk Assessment in Urban Environments: The Case of Falling Trees During Windstorm Events in Lisbon

Lopes, António; Oliveira, Sandra; Fragoso, Marcelo; Andrade, José; Pedro, Pedro
Fonte: K. Střelcová, Skvarenina, J. & Blazenec, M. Publicador: K. Střelcová, Skvarenina, J. & Blazenec, M.
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.27%
Trees bring many benefits to the urban environment. However, they may also cause hazards to human population, being the major causes of injuries and infrastructural damage during strong wind events. In the city of Lisbon, strong winds rather frequently result in tree falls, depending on the season and meteorological conditions. This paper presents a methodology to analyse tree damage due to strong wind events in urban environments. Each occurrence has been recorded by the Lisbon Fire Brigade and Rescue Services (Regimento de Sapadores Bombeiros de Lisboa - RSBL). Information provided by RSBL relating to the period of 1990-2005 was considered along with hourly wind speed and direction, species, fitossanitary conditions and urban parameters. To ensure that the fallen trees were caused by strong winds, only days with three or more occurrences of fallen trees were selected. It was found that in summer, northerly winds are responsible for 11% of tree falls, with winds from other directions (west, southwest and south) responsible for 5%. From autumn to spring, perturbed weather conditions originating from the west, southwest and south are responsible for 84% of fallen trees. The majority of tree falls occurred when wind speed surpassed 7 m/s in the six hours prior to their fall. Some recommendations to the Civil Protection Agency and the Fire Department are presented to improve the mission of collecting information. This research is a contribution to the assessment of wind risk in Lisbon.

Do habitat characteristics determine mortality risk for bats at wind

Ferreira, Daniel; Freixo, Cláudia; Cabral, João Alexandre; Santos, Regina; Santos, Mário
Fonte: Universidade de Trás-os-Montes e Alto Douro Publicador: Universidade de Trás-os-Montes e Alto Douro
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.23%
Worldwide efforts to develop sustainable methods of energy production have been increasing the use of renewable sources, with special emphasis on wind energy. Despite the clear environmental benefits associated with this type of technology, many studies have confirmed bat fatalities at wind farms, which raise concerns about the long-term effects of these structures on bat populations. To investigate the impact of windmills on bat species, we developed a spatially explicit agent-based model (ABM) to replicate the underlying behavioural mechanisms for individuals of the species Nyctalus leisleri involvedwhen navigating their habitats at a landscape level, and to simulate the associated mortality events. A set of environmental data layers was used to develop a grid representing a real landscape in termsof habitat types, foraging availability and collision-risk. Themodel variables were estimated using values fromliterature. The simulations confirmed the species predominant selection of specific foraging areas and its high mobility, evidenced by the maximum distances to roosts and home range sizes, highly correlated with the habitats coniferous forests and broadleaf forests. High wind speeds (≥4 m/s) were associatedwith a decrease in the number of expected fatalities...

Wind Pressure Evaluation for Field and Ridge Tiles

Feuze Lekem, Serge Alain
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Relevância na Pesquisa
46.13%
Wind-induced external and internal pressures on tiles installed on a low-rise building model with gable roof were investigated by using a full-scale wind testing facility generically named Wall of Wind (WoW). Emphasis was given to ridge tile where a failure usually initiates during extreme wind events. Three different profiles field tiles namely high, medium, and low were investigated in combination with two types of ridge tiles namely rounded and three-sided. Effect of weather block on the pressure was examined. The study produced a unique high resolution pressure data in the form of pressure coefficients (Cpmin, Cpmax and Cpmean) for field and ridge tiles. These tests revealed high pressure coefficients for the ridge tile compared to the field tiles including those at the corners. Ridge tiles at the middle of the roof saw slightly lower wind pressure compared to those close to the gable end. Weather blocking of clay tiles while useful preventing water intrusion, increased the wind loads on the field tiles. The case without weather blocking produced significant pressure underneath the field tiles that resulted in lower net pressures.

Wind effects on sun tracking solar reflecting panels

Wagner, Corwin J.
Fonte: Monterey, California: Naval Postgraduate School Publicador: Monterey, California: Naval Postgraduate School
Tipo: Tese de Doutorado
Relevância na Pesquisa
46.17%
Approved for public release; distribution is unlimited; Wind loads on sun tracking solar reflector panels exposed to the atmospheric boundary layer were established through surface static pressure measurements to determine how wind affects them, specifically at the request of SPAWAR-Pacific, which has developed a custom design. A 1:8 scale model of a four-panel array was studied in the Naval Postgraduate School wind tunnel. Wind velocity, wind angle orientation, and individual panel positions, at which the highest pressure coefficient cases were anticipated, were varied. The pressure coefficients were measured by an array of Scanivalve pressure transducers with 16 pressure taps drilled into the top and bottom surfaces of each panel. Oil flow and smoke flow visualization techniques were performed to better understand the flow features that led to the greatest pressure coefficients. A parapet was included to observe the wind effects of various positions. Additionally, pressure measurements were observed using a rounded edge installed on the lead panel edges. This notion was to assist in not only minimizing wind loads, but also in determining a safe stow position of the array during high wind events. The measurements and the flow visualization studies both provided a cohesive and constructive picture of the flow. The windward panel was found to be subjected to the thrust of the wind loads in most cases...

Evaluation of COAMPS performance forecasting along coast wind events during a frontal passage; Evaluation of COAMPS forecasting performance of along coast wind events during frontal passages

James, Carl S.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xii, 63 p.
Relevância na Pesquisa
36.3%
Approved for public release, distribution is unlimited; Performance of high resolution mesoscale models has been in a continuous state of refinement since their inception. Mesoscale models have become quite skillful in forecasting synoptic scale events such as mid-latitude cyclones. However, atmospheric forcing becomes a much more complicated process when faced with the challenge of forecasting near topography along the coastline. Phenomena such as gap flows, blocked flow winds and low level stratification become important to predictability at these scales. The problem is further complicated by the dynamics of a frontal passage event. The skill of mesoscale models in predicting these winds is not as well developed. This study examines several forecasts by the Coupled Ocean Atmospheric Mesoscale Prediction System (COAMPS) during frontal passage events for the Winter of 2003-2004. An attempt is made to characterize the predictability of the wind speed and direction both before and after frontal passage along the California coast. Synoptic forcing during this time is strong due to the effects of the mid-latitude cyclones propagate across the Pacific. The study's results indicate that the wind field predictability is subject to several consistent errors associated with the passage of fronts over topography. These errors arise due to difficulty in the model capturing weak thermal advection events and topographic wind funneling. The deficiencies in model representation of topography contributes to these errors.; Lieutenant...

Modelling Waves and Currents in Northeastern Lake Ontario to Assess the Impacts of a Proposed Offshore Wind Farm

McCombs, Matthew
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
36.33%
A spectral wave model (SWAN) coupled with a depth averaged hydrodynamic model (Delft3D) was used to understand the wave and flow dynamics of the Kingston Basin of Lake Ontario during large winter storm events. This model was then used to assess the impact of an offshore wind farm in the Kingston Basin. Results over different model domains with various forcing methods were compared to achieve the highest correlation with wave, current and water level observations from several locations. Storm events were modelled over the complex bathymetry of the basin and results were verified using wave and current profiler data collected during the winters of 2009-10 and 2011-12. Waves were composed of both locally generated wind sea and swell from the main basin of Lake Ontario, while flows throughout the Kingston Basin showed a complex circulation pattern. This circulation is composed of several wind-driven gyres, which are magnified during storm events. The impact of waves on the circulation patterns within the basin is highest in shallow areas where wave breaking drives circulation. To simulate a wind farm, a transmission coefficient was used in the wave model to represent the effects on waves, and an energy loss term was added to the hydrodynamic momentum equations to represent the added drag of the piles on the circulation. The results indicate that the coastal areas in eastern Lake Ontario will be minimally affected. The headlands of Big Sandy Bay...

Source Tracking Aerosols Released from Land-Applied Class B Biosolids during High-Wind Events▿

Baertsch, Carolina; Paez-Rubio, Tania; Viau, Emily; Peccia, Jordan
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.24%
DNA-based microbial source tracking (MST) methods were developed and used to specifically and sensitively track the unintended aerosolization of land-applied, anaerobically digested sewage sludge (biosolids) during high-wind events. Culture and phylogenetic analyses of bulk biosolids provided a basis for the development of three different MST methods. They included (i) culture- and 16S rRNA gene-based identification of Clostridium bifermentans, (ii) direct PCR amplification and sequencing of the 16S rRNA gene for an uncultured bacterium of the class Chloroflexi that is commonly present in anaerobically digested biosolids, and (iii) direct PCR amplification of a 16S rRNA gene of the phylum Euryarchaeota coupled with terminal restriction fragment length polymorphism to distinguish terminal fragments that are unique to biosolid-specific microorganisms. Each method was first validated with a broad group of bulk biosolids and soil samples to confirm the target's exclusive presence in biosolids and absence in soils. Positive responses were observed in 100% of bulk biosolid samples and in less than 11% of the bulk soils tested. Next, a sampling campaign was conducted in which all three methods were applied to aerosol samples taken upwind and downwind of fields that had recently been land applied with biosolids. When average wind speeds were greater than 5 m/s...

Onset of the spring bloom in the northwestern Mediterranean Sea: influence of environmental pulse events on the in situ hourly-scale dynamics of the phytoplankton community structure

Thyssen, Melilotus; Grégori, Gerald J.; Grisoni, Jean-Michel; Pedrotti, Maria Luiza; Mousseau, Laure; Artigas, Luis F.; Marro, Sophie; Garcia, Nicole; Passafiume, Ornella; Denis, Michel J.
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 12/08/2014 EN
Relevância na Pesquisa
36.22%
Most of phytoplankton influence is barely understood at the sub meso scale and daily scale because of the lack of means to simultaneously assess phytoplankton functionality, dynamics and community structure. For a few years now, it has been possible to address this objective with an automated in situ high frequency sampling strategy. In order to study the influence of environmental short-term events (nutrients, wind speed, precipitation, solar radiation, temperature, and salinity) on the onset of the phytoplankton bloom in the oligotrophic Bay of Villefranche-sur-Mer (NW Mediterranean Sea), a fully remotely controlled automated flow cytometer (CytoSense) was deployed on a solar-powered platform (EOL buoy, CNRS-Mobilis). The CytoSense carried out single-cell analyses on particles (1–800 μm in width, up to several mm in length), recording optical pulse shapes when analyzing several cm3. Samples were taken every 2 h in the surface waters during 2 months. Up to 6 phytoplankton clusters were resolved based on their optical properties (PicoFLO, Picoeukaryotes, Nanophytoplankton, Microphytoplankton, HighSWS, HighFLO). Three main abundance pulses involving the 6 phytoplankton groups monitored indicated that the spring bloom not only depends on light and water column stability...

Effect of temporal resolution of wind data on wind erosion prediction with the Revised Wind Erosion Equation (RWEQ)

Panebianco, Juan Esteban; Buschiazzo, Daniel Eduardo
Fonte: Asociación Argentina de la Ciencia del Suelo Publicador: Asociación Argentina de la Ciencia del Suelo
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
ENG
Relevância na Pesquisa
46.2%
In wind erosion modelling and assessment, wind speed is a crucial variable. Available records for large regions of the world generally show relatively low temporal resolution. The effect of using wind data of different temporal resolutions in RWEQ discrete and continuous versions was assessed. Wind erosion was measured during 82 high-wind events occurring between 2005 and 2008. Simulated and measured erosion values were compared. For wind erosion simulation during discrete periods, the model was loaded with wind speeds averaged in 5 minutes and 1 hour- intervals. For continuous simulation, a weather file for RWEQ/ 97 was developed and Weibull factors were calculated using both hourly and daily wind speeds. When the discrete version of RWEQ was used with hourly wind speeds instead of five-minute averages, the total simulated soil loss was reduced by 44%. The model efficiency was not significantly affected by wind speed data resolution. RWEQ continuous version, loaded with monthly Weibull parameters using hourly wind speeds, calculated zero erosion. Monthly Weibull distribution scale factors calculated using daily wind speeds were reduced by 32% on average with respect to hourly data. Increasing the Weibull scale parameter by up to 50% slightly improved the monthly simulated erosion rates. Using low resolution wind speed data reduces the model outputs. This may be corrected but a large amount of field information is needed.; Fil: Panebianco...

Analysis of wind events in a coastal area: a tool for assessing turbulence variability for studies on plankton; Análisis de episodios de viento en un área costera: una herramienta para la estimación de la variabilidad en la turbulencia en estudios con plancton

Guadayol, Òscar; Peters, Francesc
Fonte: Consejo Superior de Investigaciones Científicas (España) Publicador: Consejo Superior de Investigaciones Científicas (España)
Tipo: Artículo
ENG
Relevância na Pesquisa
66.38%
[EN] Turbulence at different scales, from generation to dissipation, influences planktonic communities. Many experimental studies have recently been done to determine the effects of small-scale turbulence on plankton, but it is difficult to state the relevance of the findings since there is little unbiased information on turbulence variability in the sea. In this study, we use wind velocity data series from several meteorological stations located along the Catalan coast to estimate the spatial and temporal variability of small-scale turbulence in the upper ocean. Using a peaks-over-threshold approach, we develop a statistical model to assess the frequency of wind events as a function of their persistence and intensity. Finally, the wind speed data series are converted into turbulent energy dissipation rate estimates at 1 m depth to determine the general distribution of turbulence on the Catalan coast. Geographical variability is larger than seasonal variability in frequency and persistence of wind events, owing to differences in local relief. These statistical models developed for wind events combined with empirical relationships between wind and turbulence, are tools for estimating the occurrence and persistence of turbulent events at a given location and season. They serve to put into context the past...

Two key parameters for the El Ni?o continuum: Zonal wind anomalies and Western Pacific subsurface potential temperature

Lai, Andy Wang-Chun; Herzog, Michael; Graf, Hans F.
Fonte: Springer Publicador: Springer
Tipo: Article; accepted version
EN
Relevância na Pesquisa
36.24%
This is the author accepted manuscript. The final version is available via Springer at http://link.springer.com/article/10.1007%2Fs00382-015-2550-0.; Different types of El Ni?o (EN) events have recently been discussed. Based on NCEP-NOAA reanalysis data this analysis explores a number of key parameters that cause a range of EN types over the period 1980-2013. EN events are divided into three types depending on the spatial and temporal evolution of the sea surface temperature anomalies (SSTA): Central Pacific (CPEN), Eastern Pacific (EPEN), and Hybrid (HBEN). We find that EN is a continuous spectrum of events with CPEN and EPEN as the end members. This spectrum mainly depends on two key parameters: the 130?E-160?E Western Pacific 5m-250m subsurface oceanic potential temperature anomaly (PTA) about one year before the EN peak (typically January and February), and the 140?E-160?W cumulative zonal wind anomaly (ZWA) between onset and peak of the EN event. Using these two parameters, about 70% of the total variance of the maximum SSTA realised in different Ni?o regions can already be explained up to six months before the maximum SSTA occurs. This offers a rather simple potential for ENSO prediction. A necessary condition for the evolution of an EPEN...

BALANCING WIND DOWN RAMPS WITH DEMAND RESPONSE: The opportunity for load participation in ancillary service markets spurred by high wind penetration

Ballal, Sangeeta; Nourafshan, Andrew; Brumleve, Nicholas
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Masters' project
Publicado em 27/04/2012
Relevância na Pesquisa
36.21%
Large “down-ramps,” inherent in the pronounced variability of wind power generation, are a threat to grid stability as the share of wind resources increases in power markets. Balancing Authorities face the challenge of how best to address the externalities that wind variability places on the grid. Our analysis assesses U.S. power markets that offer the greatest opportunities for demand response to act as a wind balancing resource. More specifically, this study evaluates market opportunities for third-party demand response aggregators to bid the capacity of responsive load into ancillary services markets to address these “down-ramp” events. This evaluation was performed through both the establishment of a qualitative framework and the creation of a quantitative, Microsoft Excel-based, model. In the qualitative framework, we reviewed the existing wind integration literature to identify the critical characteristics of a balancing authority that are predictive of the local grid’s relative capability to accommodate wind ramping behavior. In this framework, we additionally outline key qualities of loads that make them viable candidates for the demand response services required in the balancing of wind ramps. Lastly, we discuss several potential approaches for forecasting future wind penetration in a balancing authority. We have found that demand response for wind balancing can be a favorable emerging business opportunity in a power system at the confluence of these three aforementioned analyses: 1) the balancing authority’s structure and other conditions lead to a limited ability to effectively respond to increasing wind penetration...

Balancing Wind Down Ramps With Demand Response: The opportunity for load participation in ancillary service markets spurred by high wind penetration

Nourafshan, Andrew; Ballal, Sangeeta; Brumleve, Nick
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Masters' project
Publicado em 27/04/2012 EN_US
Relevância na Pesquisa
36.21%
Large “down-ramps,” inherent in the pronounced variability of wind power generation, are a threat to grid stability as the share of wind resources increases in power markets. Balancing Authorities face the challenge of how best to address the externalities that wind variability places on the grid. Our analysis assesses U.S. power markets that offer the greatest opportunities for demand response to act as a wind balancing resource. More specifically, this study evaluates market opportunities for third-party demand response aggregators to bid the capacity of responsive load into ancillary services markets to address these “down-ramp” events. This evaluation was performed through both the establishment of a qualitative framework and the creation of a quantitative, Microsoft Excel-based, model. In the qualitative framework, we reviewed the existing wind integration literature to identify the critical characteristics of a balancing authority that are predictive of the local grid’s relative capability to accommodate wind ramping behavior. In this framework, we additionally outline key qualities of loads that make them viable candidates for the demand response services required in the balancing of wind ramps. Lastly, we discuss several potential approaches for forecasting future wind penetration in a balancing authority. We have found that demand response for wind balancing can be a favorable emerging business opportunity in a power system at the confluence of these three aforementioned analyses: 1) the balancing authority’s structure and other conditions lead to a limited ability to effectively respond to increasing wind penetration...

Balancing Wind Down Ramps With Demand Response: The opportunity for load participation in ancillary service markets spurred by high wind penetration

Brumleve, Nick; Ballal, Sangeeta; Nourafshan, Andrew
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Masters' project
Publicado em 27/04/2012 EN_US
Relevância na Pesquisa
36.22%
Large “down-ramps,” inherent in the pronounced variability of wind power generation, are a threat to grid stability as the share of wind resources increases in power markets. Balancing Authorities face the challenge of how best to address the externalities that wind variability places on the grid. Our analysis assesses U.S. power markets that offer the greatest opportunities for demand response to act as a wind balancing resource. More specifically, this study evaluates market opportunities for third-party demand response aggregators to bid the capacity of responsive load into ancillary services markets to address these “down-ramp” events. This evaluation was performed through both the establishment of a qualitative framework and the creation of a quantitative, Microsoft Excel-based, model. In the qualitative framework, we reviewed the existing wind integration literature to identify the critical characteristics of a balancing authority that are predictive of the local grid’s relative capability to accommodate wind ramping behavior. In this framework, we additionally outline key qualities of loads that make them viable candidates for the demand response services required in the balancing of wind ramps. Lastly, we discuss several potential approaches for forecasting future wind penetration in a balancing authority. We have found that demand response for wind balancing can be a favorable emerging business opportunity in a power system at the confluence of these three aforementioned analyses: 1) the balancing authority’s structure and other conditions lead to a limited ability to effectively respond to increasing wind penetration...

Effect of temporal resolution of wind data on wind erosion prediction with the revised wind erosion equation (RWEQ)

Panebianco,Juan E; Buschiazzo,Daniel E
Fonte: Ciencia del suelo Publicador: Ciencia del suelo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2013 EN
Relevância na Pesquisa
46.2%
In wind erosion modelling and assessment, wind speed is a crucial variable. Available records for large regions of the world generally show relatively low temporal resolution. The effect of using wind data of different temporal resolutions in RWEQ discrete and continuous versions was assessed. Wind erosion was measured during 82 high-wind events occurring between 2005 and 2008. Simulated and measured erosion values were compared. For wind erosion simulation during discrete periods, the model was loaded with wind speeds averaged in 5 minutes and 1 hour- intervals. For continuous simulation, a weather file for RWEQ/ 97 was developed and Weibull factors were calculated using both hourly and daily wind speeds. When the discrete version of RWEQ was used with hourly wind speeds instead of five-minute averages, the total simulated soil loss was reduced by 44%. The model efficiency was not significantly affected by wind speed data resolution. RWEQ continuous version, loaded with monthly Weibull parameters using hourly wind speeds, calculated zero erosion. Monthly Weibull distribution scale factors calculated using daily wind speeds were reduced by 32% on average with respect to hourly data. Increasing the Weibull scale parameter by up to 50% slightly improved the monthly simulated erosion rates. Using low resolution wind speed data reduces the model outputs. This may be corrected but a large amount of field information is needed.

Numerical simulation of wind gusts in intense convective weather and terrain-disrupted airflow

CHAN,P. W.; LAM,C. C.; CHEUNG,P.
Fonte: Centro de Ciencias de la Atmósfera, UNAM Publicador: Centro de Ciencias de la Atmósfera, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2011 EN
Relevância na Pesquisa
46.17%
Wind gust is an important element in weather forecasting. Gusts associated with squalls in intense convective weather may bring about injuries to the public. In aviation meteorology, the aircraft may not attempt to land on the runway in gusty crosswinds, which could disrupt air traffic and adversely affect airport efficiency. The conventional method of gust forecasting is mainly based on climatological information of wind excess due to gust on top of the mean wind for different synoptic and mesoscale conditions (e.g. subtropical squall line, monsoonal flow, tropical cyclone situation, etc.). This paper uses a physical approach to wind gust estimate in meso to microscale numerical weather prediction (NWP), namely, based on turbulent kinetic energy and vertical air motion as applied to Regional Atmospheric Modelling System (RAMS) version 4.4, and examines its performance in different conditions of gusty winds at the Hong Kong International Airport (HKIA). For the typical gusty wind events considered in the paper, the performance of the wind gust estimate is found to be satisfactory in comparison with actual wind measurements at the airport (yes-yes case, viz. the actual gusty winds are captured by the wind gust estimate method). To demonstrate that the method does not over-estimate the gust (null-null case...