The viability of balancing wind generation with large scale energy storage

This paper studies the impact of combining wind generation and dedicated large scale energy storage on the conventional thermal plant mix and the CO₂ emissions of a power system. Different strategies are proposed here in order to explore the best operational strategy for the wind and storage system in terms of its effect on the net load. Furthermore, the economic viability of combining wind and large scale storage is studied. The empirical application, using data for the Irish power system, shows that combined wind and storage reduces the participation of mid-merit plants and increases the participation of base-load plants. Moreover, storage negates some of the CO₂ emissions reduction of the wind generation. It was also found that the wind and storage output can significantly reduce the variability of the net load under certain operational strategies and the optimal strategy depends on the installed wind capacity. However, in the absence of any supporting mechanism none of the storage devices were economically viable when they were combined with the wind generation on the Irish power system.     

利用能值方法评价沼气工程性能——山东淄博案例分析

运用能值分析方法对山东省淄博市畜禽养殖场沼气工程和秸秆发酵沼气工程的投入和产出进行了计算和分析,结果显示:畜禽养殖场沼气工程的生态经济价值为2.38×105$/a,秸秆沼气工程为4.07×105$/a,两种沼气工程均具有很高的生态经济价值。通过能值指标综合对比,评价了淄博市两类沼气工程的效益和可持续发展能力,对比结果表明:畜禽养殖场沼气工程购入能值比率、能值投资率为秸秆沼气工程的0.3倍和0.17倍,自然能值与购入能值比、能值产出率和能值自给率分别是秸秆沼气工程的5.78倍、1.77倍和1.7倍;废弃物处理率是秸秆沼气工程的1.7倍,环境负荷率为秸秆沼气工程的0.2倍;能值反馈率是秸秆沼气工程的52倍,可更新率是秸秆沼气工程的1.44倍,可持续发展指标是秸秆沼气工程的9.25倍。     

风电新能源发展与并网技术分析评价

随着能源紧张局势不断升级和环保呼声日益高涨,可再生能源的开发和利用受到世界各国高度关注,其中风能就是目前技术最为成熟的新能源类型之一,并且得到了迅猛发展,同时也带来一系列的影响和问题,对输电网的安全和经济运行都会带来冲击。文章分析了风电新能源的技术发展现状,就风电技术的发展趋势进行了综合评述。     

Optimization of wind turbine energy and power factor with an evolutionary computation algorithm

An evolutionary computation approach for optimization of power factor and power output of wind turbines is discussed. Data-mining algorithms capture the relationships among the power output, power factor, and controllable and non-controllable variables of a 1.5 MW wind turbine. An evolutionary strategy algorithm solves the data-derived optimization model and determines optimal control settings. Computational experience has demonstrated opportunities to improve the power factor and the power output by optimizing set points of blade pitch angle and generator torque. It is shown that the pitch angle and the generator torque can be controlled to maximize the energy capture from the wind and enhance the quality of the power produced by the wind turbine with a DFIG generator. These improvements are in the presence of reactive power remedies used in modern wind turbines. The concepts proposed in this paper are illustrated with the data collected at an industrial wind farm.     

基于熵关联数据挖掘的MPSO-Elman风电功率预测

为进一步提高风电功率预测计算效率及准确性,建立基于熵关联数据挖掘的MPSO-Elman风电功率预测模型:在分析信息熵与互信息的熵相关系数(ECC)后,对各个历史日数据样本和待测时段参考样本间的复杂非线性映射关系进行量化评估,经过高关联度样本筛选,Elman模型隐含层结构优化以及权值初值选取改进,最后采用改进粒子群算法(MPSO)对网络参数进一步优化,并以某风电场实测数据为依据进行实例分析。结果表明,该模型使得功率预测准确度达到91.24%,预测效果要优于RBF-BP模型,证明了该模型的先进性与有效性。     

Analysis of wind flow around a parabolic collector (1) fluid flow

Applications of parabolic collectors for solar heating and solar thermal power plant increased in the recent years. Most of the solar power plants installed with parabolic collectors are on flat terrain and they may be subjected to some environmental problems. One of problems for large parabolic collector is their stability to track the sun with respect to time very accurately. Any small off tracking as well as the collector structure stability will be affected by strong wind blowing for the regions where the wind velocity is high.In the present study, a two-dimensional numerical simulation of turbulent flow around a parabolic trough collector of the 250 kW solar power plants in Shiraz, Iran is performed taking into account the effects of variation of collector angle of attack, wind velocity and its distribution with respect to height from the ground.Computation is carried for wind velocity of 2.5, 5, 10, and 15 m/s and collector angles of 90°, 60°, 30°, 0°, −30°, −60°, and −90° with respect to wind directions. Various recirculation regions on the leeward and forward sides of the collector are observed, and both pressure field around the collector and total force on the collector are determined for each condition. The effect of absorber tube on the flow field was found negligible, while the effect of the gap between the two sections of parabola at midsection and the gap between the collector and ground were found considerable on both flow field and pressure distribution around the collector.     

Application of combined analytical/FEA coupled aero-structure simulation in design of wind turbine adaptive blades

This paper demonstrates the application of combined analytical/FEA coupled aero-structure simulation in design of bend-twist adaptive blades. A genetic algorithm based design tool, in which the power curve is predicted through a combined coupled aero-structure simulation, has been developed. A bend-twist adaptive blade has been designed to be used on the rotor of a constant speed stall regulated wind turbine. The bend-twist adaptive blade is assumed to be made out of anisotropic composite materials. The designed blade has the same aerofoil and chord distribution as the original blade used on the wind turbine, but with a different pre-twist distribution. The simulated results show a significant improvement in the average power of the studied stall regulated wind turbine when employing the designed adaptive blades.     

Investigation of wind characteristics and wind energy potential in Kirklareli, Turkey

Utilization of wind energy as an energy source has been growing rapidly in the whole world due to environmental pollution, consumption of the limited fossil fuels and global warming. Although Turkey has fairly high wind energy potential, exploitation of the wind energy is still in the crawling level. In the current study, wind characteristics and wind energy potential of Kırklareli province in the Marmara Region, Turkey were analyzed taking into account the wind data measured as hourly time series. The wind data used in the study were taken from Electrical Power Resources Survey and Development Administration (EIEI) for the year 2004. The measured wind data were processed as annual, seasonal and monthly. Weibull and Rayleigh probability density functions of the location are calculated in the light of observed data and Weibull shape parameter k and scale parameter c are found as 1.75 and 5.25 m/s for the year 2004. According to the power calculations done for the site, annual mean power density based on Weibull function is 138.85 W/m². The results indicate that investigated site has fairly wind energy potential for the utilization.     

Crosswind action on rail vehicles: Wind tunnel experimental analyses

Extensive wind tunnel tests have been carried out on train scale models. The experimental tests have been performed on three types of rail vehicles, in different configurations. The wind tunnel tests allowed to point out the most critical wind conditions with respect to running safety and to perform a sensitivity analysis on the principal parameters that can influence the aerodynamic behaviour of rail vehicles. In particular, the effects of the turbulence intensity and of the train motion on the aerodynamic coefficients have been studied.     

Detection of Cryptosporidium spp. and Giardia duodenalis in surface water: A health risk for humans and animals

The objective of the present study was to determine the degree of contamination by Cryptosporidium spp. and Giardia duodenalis in a river basin in a livestock farming area in Galicia (NW, Spain). Water samples (50 l) were collected at 22 points in the main basin (including 5 recreational areas), and at the source and mouth of the 3 most important rivers and at the mouth of a smaller, secondary river. Faecal samples were collected from dairy cattle selected at random from 18 herds farmed in the area. A total of 139 neonatal calves, 480 heifers and 697 cows were sampled. The prevalence, intensity of infection and the risk associated with the spread of infection by both enteropathogens were determined. Water and faecal samples were collected in spring, summer, autumn and winter of 2007. The species and genotypes of these parasites present in the water samples were identified. In both water and faecal samples, more parasitic stages were collected in spring and summer than in autumn and winter. In spring, Cryptosporidium spp. oocysts were detected in 33 (9.4%) cows from 13 (72.2%) herds, and G. duodenalis cysts were detected in 56 (16.0%) cows from 15 farms (83.3%); the intensity of infection ranged from 5 to 7895 G. duodenalis cysts per gram of faeces. Infective stages of Cryptosporidium spp. and G. duodenalis were also detected in respectively 26 (89.6%) and 27 (93.1%) water samples, in spring. The mean concentrations of parasites ranged from 2 to 1200 Cryptosporidium spp. oocysts per litre and from 2 to 400 G. duodenalis cysts per litre. Cryptosporidium parvum, C. andersoni, C. hominis and assemblages A-I, A-II, E of G. duodenalis were detected. The presence of both protozoans must be monitored in cattle, in sources of water used for recreational purposes and in artificial waterways used by farmers (water channels, animal drinking water and drainage systems).