Feasibility assessment of a leading-edge-flutter wind power generator

This study addresses the preliminary technical feasibility assessment of a mechanical apparatus for conversion of wind energy. The proposed device, designated as “leading-edge-flutter wind power generator”, employs aeroelastic dynamic instability of a blade airfoil, torsionally rotating about its leading edge. Although the exploitation of aeroelastic phenomena has been proposed by the research community for energy harvesting, this apparatus is compact, simple and marginally susceptible to turbulence and wake effects. The objective of this study was to identify a conceptual configuration that could become operational at low and medium wind speeds. Pre- and post-critical regimes are simulated; the prediction of mechanical efficiency in the absence of dissipation is also discussed.     

Event mean concentration and loading of litter from highways during storms

Total captured gross pollutants in stormwater runoff were monitored at six Southern California highway sites over 2 years. Gross pollutants were defined as larger than 0.5 cm and were classified into three categories. The gross pollutants were 90% vegetation and 10% litter. Approximately 50% of the litter was composed of biodegradable materials. Event mean concentrations and mass emission rates are presented. No statistically significant correlations of litter production were noted, although the event mean concentrations show an increasing trend with antecedent dry days and a decreasing trend with total runoff volume or total rainfall. The mass emission rates will be useful to estimate total litter production for developing total maximum daily loads.     

风电和市电互补数采系统设计

文章研究了一种风/市电互补系统,功率监控系统应该具有信息收集功能,根据数据采集系统采集并上传的信息建立完整的数据库;具有实时功能,通过数据采集系统采集的数据应该第一时间反映到移动终端的APP中;具有远程监视功能,由收集的数据建立数据库,并通过APP反映到移动终端上,便于监控人员远程监控;具有便捷的用户界面,可以直观反映系统信息,便于一般用户操作系统。     

厦门开发利用太阳能与风能的可行性分析

2003年的中国“电荒”给我们的电力系统敲响了警钟,也让我们重新思考中国的电力结构是否合理,将来如何发展电力来适应经济的发展,是走以牺牲环境为代价的煤电、核电道路呢,还是走可持续发展的绿色能源道路?这是需要我们谨慎抉择的。     

A new direct version of the Cook-Mayne method for wind pressure probabilities in temperate storms

The original Cook-Mayne (CM) method for obtaining a wind pressure or load of a prescribed probability is reviewed. A new direct calculation method is introduced. This does not require either Monte Carlo simulations or the assumption that extreme pressures conform to the ultimate Fisher-Tippett Type I asymptote. The required value is calculated directly with no intermediate stages. The new method still relies on the original assumptions that both the pressure coefficient and the wind dynamic head have extremes which conform to the ultimate FT1 asymptote.Violation of these two assumptions is studied in some cases where calculations based on these assumptions are compared with exact results. The direct CM method is found to retain accuracy in spite of departures from the assumptions and therefore can provide a robust design tool.     

海上风电基础研究现状

海上风电基础作为海上风机重要组成部分,在不同工况环境条件下受到了波浪、风、地震、冲击等各种动力荷载的交互作用,介绍了不同种类海上风电基础适用条件、研究现状,对风电行业基础的研发和设计提供了理论指导。     

Contested overruns and performance of offshore wind power plants

Offshore wind power plants are expected to expand rapidly in the coming years. These large engineering construction projects are important for climate change mitigation. The paper contributes to socio-technical understanding of engineering construction. Cost, time, delays and performance results of selected British plants are investigated, with a focus on strategic misrepresentation. This megaproject concept is combined with a socio-technical content analysis of offshore wind farms and provides a technologically precise and contemporary conceptualization in comparison with complex engineering and megaproject approaches. Based on publicly available data, budget and time overruns and underperformance are demonstrated. Budget overruns range from 0% to 65%; time overruns from 9% to 100%, Operational performance indicators reveal plants far below and just below estimations. These are all indications of strategic misrepresentation, but according to project players, the delays originate from weather, product technology, site features and processes. The findings thus indicate a latent controversy regarding reasons for overruns. A socio-technical variant of reference class forecasting (RCF) is developed to explore whether RCF could improve the estimates. Socio-technical RCF is developed for 10 plants that share foundation, national and geotechnical conditions. This provides an illustrative example of a proposed uplift for London Array. Such an RCF should be orchestrated with more governance mechanisms in order to improve future investments in engineering construction, including offshore plants.     

风电火灾原因及防火对策

通过对风能特点与消防关系的分析,找出引发风电火灾的原因,如雷击、电气、机械故障、人为因素等,提出增设固定报警灭火系统、防火分隔控制、加强消防技术研究、制定相关标准、加强日常防火监督等预防风电火灾的对策.     

Simulating impacts of wind farms on local hydrometeorology

Wind power is one of the fastest growing energy sources in the world, most of the growth being in large wind farms that are often located on agricultural land near residential communities. This study explores the possible impacts of such wind farms on local hydrometeorology using a mesoscale model equipped with a rotor parameterization based on data from a commercial wind turbine. Results show that wind farms significantly affect near-surface air temperature and humidity as well as surface sensible and latent heat fluxes. The signs of the impacts, i.e., increase or decrease, depend on the static stability and total water mixing ratio lapse rates of the atmosphere. The magnitudes of these impacts are not only constrained by the hub-height wind speed but also depend to some extent on the size of the wind farms. Wind farms also affect the hydrometeorology of an area up to 18-23 km downwind. More work is required to conclusively estimate the length-scale of wind farm wakes. This study is one of the first few to provide realistic estimates of possible impacts of wind farms. The model developed and used in this study can help in assessing and addressing the environmental impacts of wind farms thereby ensuring the long-term sustainability of wind power.     

Prediction of wind speed for the estimation of wind turbine power output from site climatological data using artificial neural network

In this paper, the wind speeds of Noupoort in the Western Cape region of South Africa are forecasted from the site climatological data using feed forward artificial neural network (ANN) with the back propagation training method. Different architectural designs are tested with different combinations of climatological data to obtain the most suitable ANN for predicting the wind speed of the site. The predicted wind speeds are compared with the actual measured wind speeds and the results are evaluated using mean absolute error (MAE), mean absolute percentage error (MAPE), root mean square error (RMSE) and correlation coefficient (R). Some of the key results show that combination of temperature, wind direction and time of the day (TEM?+?WD?+?T) could effectively predict wind speed of Noupoort. The forecasted wind speed shows a strong agreement with the measured wind speed with R, RMSE, MAPE and MAE of 0.96, 0.56, 6.64% and 0.44, respectively.     

我国陆上风电场风机基础形式研究

对目前国内陆上风电场常见的基础形式进行了介绍,并对重力式扩展基础、桩基础、岩石锚杆基础、预应力墩式基础、梁板式基础的优缺点进行了比较分析,为风电场建设时选择合理的基础形式提供了参考依据。     

Defect distribution and reliability assessment of wind turbine blades

In this paper, two stochastic models for the distribution of defects in wind turbine blades are proposed. The first model assumes that the individual defects are completely randomly distributed in the blade. The second model assumes that the defects occur in clusters of different size, based on the assumption that one error in the production process tends to trigger several defects. For both models, additional information, such as number, type, and size of the defects, is included as stochastic variables.In a numerical example, the reliability is estimated for a generic wind turbine blade model both with and without defects in terms of delaminations. The reliability of the blade decreases when defects are included. However, the distribution of the defects influences how much the reliability is decreased. It is also shown how non-destructive inspection (NDI) after production can be used to update the reliability for the wind turbine blade using Bayesian statistics.     

国家发展改革委关于完善风力发电上网电价政策的通知发改价格[2009]1906号

各省、自治区、直辖市发展改革委、物价局: 为规范风电价格管理,促进风力发电产业健康持续发展,依据<中华人民共和国可再生能源法>,决定进一步完善我委印发的<可再生能源发电价格和费用分摊管理试行办法>(发改价格[2006]7号)有关规定.     

An assessment of the respective contributions of flow-rate and concentration variations to mass discharge variations at the outlets of two combined catchments during rain events

This paper presents a method for assessing the respective contributions of the variations of flow-rate and concentration of any pollution parameter to the variations of the mass discharge of the same parameter. This method uses a specially designed decomposition of variance, which gives a priority to the information provided by flow-rates, either directly, or through the correlation between flow-rates and concentrations. To demonstrate the potential interest of this method, data monitored on two catchments in the city of Paris (France) are processed according this method, with turbidity being used as a surrogate for suspended solids concentration. Results show that volumes provide a fairly good evaluation of masses at the scale of whole events. Inside any particular event, concentrations are major contributors to the variations of mass discharge, despite the correlations between flow rate and concentration which may be observed for many rain events.     

Collapse mechanisms of power towers under wind loading

In this paper, nonlinear static pushover analyses were carried out to assess the capacity and collapse mechanism of two existing transmission towers under wind loading. Different load distribution patterns were adopted from the application of the codified design wind load of the following countries: Mexico, United States, India, Japan and the New Zealand – Australian Code. Three-dimensional inelastic response analyses were performed using open access software. Analyses were employed to define the capacity curves, stress-strain curves for structural elements, the yielding mapping sequences and the collapse mechanisms, and to evaluate the influence of the tower body deformation and to assess the theoretical overstrength and ductility capacities. Results show a damage concentration, which leads to a fragile collapse mechanism with important strength reserves and a non-uniform distribution of yielding within the tower height. Since the collapse mechanism is not compatible with the desired performance inherent to the design philosophy, recommendations for the design stage are proposed, which pretend to ensure that the inelastic behaviour be consistent with the goals implicit in a code-based design to prevent tower collapses.     

Linear and nonlinear models in wind resource assessment and wind turbine micro-siting in complex terrain

The current trend of increasing the electricity production from wind energy has led to the installation of wind farms in areas of greater orographic complexity, raising doubts on the use of simple, linear, mathematical models of the fluid flow equations, so common in the wind energy engineering. The present study shows how conventional techniques, linear models and cup anemometers, can be combined with flow simulation by computational fluid dynamics techniques (nonlinear models) and measurements by sonic anemometers, and discuss their relative merits in the characterisation of the wind over a coastal region—a cliff over the sea. The computational fluid dynamic techniques were particularly useful, providing a global view of the wind flow over the cliff and enabling the identification of separated flow regions, clearly unsuitable for installation of wind turbines. These locations display a pulsating flow, with periods between 1 and 7 min, in agreement with sonic anemometer measurements, and both a turbulence intensity and a gust factor well above the wind turbine design conditions.     

居住小区风环境模拟与分析

为了分析居住小区行列布置形式对小区风环境的影响,构建了居住小区行列布置形式模型,并利用CFD软件模拟小区内流场,提出了有助于小区规划的措施与建议,从而改善小区的风环境。     

Analysis of height variations of sodar-derived wind speeds in Northern Spain

The Weibull distribution has been widely used in wind speed analysis. Ten-min averages from a sodar placed in an extensive plateau in the North of Spain were considered. The measuring period was April 2001. Daily wind speed evolution has been analysed and a sharp contrast between day and night has been obtained. Contrasting behaviour between surface and more distant levels has also been seen. The strong convection during the day and the stratification stability during the night were responsible for this well-defined pattern. Four wind speed intervals for a typical wind turbine were considered. Low wind speeds showed no directional character, although moderate winds came from two prevailing directions due to the synoptic weather systems affecting the Iberian Peninsula with a 5-6 day period. Ground influence was present only at lowest levels. As a result, the behaviour of wind speed derived from surface data must be avoided. Although moderate winds were frequent, a persistence analysis revealed the low number of lasting runs. The wind speed power law was also analysed and the usual one-seventh expression was proved not to be valid. The Weibull parameters were calculated by four methods: linear regression by cumulative frequency, moments, maximum likelihood and quartiles. The equivalence was in general clear. Finally, height analysis revealed that the shape parameter was around two whereas major differences were reached for the scale factor. A successful fit with the height was proved for the latter. Finally, a well-defined daily evolution was obtained, indicating that selection of a site for energy generation purposes must be preceded by a temporal study based on direct height measurements.     

离网风电-网电互补供电的载荷模拟试验研究

基于离网风电-网电互补供电试验研究,设计了以计算机编程调制载荷的磁粉制动器加载装置,并在搭建的试验平台上,试验研究了加载装置模拟实际载荷特性,以及互补双电源向负载供电的切换控制技术.试验结果表明,加载装置的响应速度和加载精度可真实反映模拟实际载荷特性,互补双电源的切换控制技术可靠、稳定,提高了风能利用率.     

Calibration of the descent local search algorithm parameters using orthogonal arrays

Solving optimization problems using heuristic algorithms requires the selection of its parameters. Traditionally, these parameters are selected by a trial and error process that cannot guarantee the quality of the results obtained because not all the potential combinations of parameters are checked. To fill this gap, this paper proposes the application of Taguchi's orthogonal arrays to calibrate the parameters of a heuristic optimization algorithm (the descent local search algorithm). This process is based on the study of the combinations of discrete values of the heuristic tool parameters and it enables optimization of the heuristic tool performance with a reduced computational effort. To check its efficiency, this methodology is applied to a technical challenge never studied before: the optimization of the tensioning process of cable‐stayed bridges. The statistical improvement of the heuristic tool performance is studied by the optimization of the tensioning process of a real cable‐stayed bridge. Results show that the proposed calibration technique provided robust values of the objective function (with lower minimum and mean values, and lower standard deviation) with reduced computational cost.