考虑需求差异化和配电网运行风险的充电站规划

针对电动汽车充电站规划与用户需求及配电网运行的适配性问题,在采用EV空间转移概率模型来模拟用户出行不确定性时考虑充电站规划对用户充电行为的影响;综合建设成本、用户充电体验和配电网运行风险等需求建立充电站规划目标;建立空间权重来反映不同功能区域对充电站需求的差异,提出计及空间权重的两级加权Voronoi图进行充电站服务范围分区;分别基于粒子群优化算法和循环支路替换法提出充电站选址定容和充电负荷接入节点优化方法。以一个规划区为例,通过不同充电站数下规划方案对比选出最优方案,结果表明,考虑空间权重的TWVD分区方法比加权Voronoi图具有更好的分区效果。     

基于已有充电站调整的电动汽车充电站选址研究

针对充电站选址决策中未考虑已有充电站调整对新建充电站选址的影响这一问题,提出一种基于已有充电站调整的电动汽车充电站选址模型。首先,引入中间变量构造分段非线性函数来描述已有充电站和新建充电站之间的关系;然后,以最小化充电站投资总成本和用户充电距离的综合偏离函数作为目标函数,构建基于已有充电站调整的电动汽车充电站选址模型;最后,通过仿真实验验证了本文所构建模型的有效性和合理性。仿真结果表明：在电动汽车充电站选址过程中考虑已有充电站的调整,可以有效降低规划成本和网损成本;已有充电站调整类型和新建充电站选择方案与规划者对充电距离和成本的偏好程度有关。     

EV充电站选址定容及基于蚁群算法概念的建设规划方案研究

随着各类新能源汽车的不断普及,服务于大规模电动汽车(EV)的配套充电设施也同步进行建设。提出了基于实际环境条件及用户实际需求的充电桩选址定容方案,能够应用于电动汽车充电站建设的实际规划。提出基于蚁群算法概念的充电站时序建设规划算法,通过对计划建设的充电站进行重要程度评估,为决策人员提供充电站建设顺序的建议。通过仿真验证规划方案的可行性和有效性,提供充电站规划综合方案。     

考虑安全效能成本的电动汽车充电站多目标规划方法

近年来,随着电动汽车的不断增多,其充电需求给配电网的规划和运行带来了一系列的问题。为解决这一问题,该文提出一种考虑安全效能成本的配电网充电站多目标规划方法。首先,构建考虑电压质量的配电网安全效能成本指标体系,然后在此基础上构建充电站规划模型,并采用向量序优化算法进行求解。最后通过基于25节点交通系统和IEEE33节点配电网系统的算例验证了该模型和算法的有效性和可行性。     

基于多源数据的电动汽车充电设施布局优化方法研究

针对电动汽车充电设施布局与电动汽车用户需求平衡性问题,提出了一种基于多源数据的电动汽车充电设施布局优化方法。首先,基于兴趣点位置、用户产生充电需求时的地点、需求偏好等多源数据构建电动汽车充电站双层布局优化模型。上层模型以社会总成本为目标函数对电动汽车充电站进行选址定容优化;下层模型以寻址距离、寻址时间、拥挤程度3个指标搭建用户最佳选择模型;然后,利用遗传算法对双层规划模型进行求解,获得电动汽车充电站布局优化方案。最后,通过实例验证了所提方法的可行性。     

考虑电动汽车行驶特性的工业园区电动汽车充电设施规划

[目的]为响应国家节能环保的号召,促进新能源汽车推广与应用,各地市政府不断加大政策支持力度,有力推动了电动汽车充电基础设施发展,随着国内大型工业园区日益增多,提前合理布局电动汽车充电基础设施对推动园区电动汽车快速发展具有重要意义。[方法]分析了电动汽车充电特性和行驶特性,然后建立了充电站建设成本和充电成本的综合最优模型,考虑地理信息系统根据充电设施网格化规划布局方法,采用Pareto求解算法提高了充电设施寻优布局效率;其次,针对不同充电时间和充电成本,对电动汽车充电设施投资回收期进行对比分析。[结果]研究表明:获得了地区充电设施布局规划建设的最优方案,达到提升充电设施设备利用效率,提高投资效益的作用。[结论]通过对珠三角某工业园区充电站规划的实例进行对比分析,表明了本次规划方案的可行性和有效性。     

基于改进随机森林算法的电动汽车充电预测

为了应对电动汽车充电需求规模越来越大的现状,提出了一种基于针对单一充电站负荷的随机森林电动汽车充电负荷预测方法,通过对Cart回归算法完成对于具体充电站的短期充电负荷预测,从时间及空间角度对区域内各充电站充电负荷的数据分析,将该算法付诸实践,确定了当前电动汽车充电负荷数据在算法中的应用形式,并验证了预测算法的准确性,能可靠投入实用,通过充电负荷的预测为供电商和用户提供参考。     

基于亨利气体溶解度优化算法的电动汽车二阶段优化调度方法

针对如何有效管理电动汽车充电负荷,优化电动汽车充电调度以减少充电时间和能量消耗的问题,提出了一种基于亨利气体溶解度优化算法的电动汽车二阶段优化调度方法。第1阶段通过整数线性规划以各电动汽车能量消耗最少到达有充电空位的充电站为目标,将最适宜的充电站分配给电动汽车;第2阶段以充电站运营商日充电总费用最小为目标,考虑电动汽车充电率、能量需求和荷电状态等约束,基于亨利气体溶解度优化算法最大限度地降低充电站运营商的日充电总费用。最后,通过仿真实验将所提方法与粒子群优化算法、遗传算法等进行对比,仿真结果验证了所提方法的有效性。     

考虑交通流量的电动汽车充电站优化规划方法

城市电动汽车保有量快速增长使充电站优化规划问题日益受到配电网规划领域的广泛关注。综合考虑城市交通流量空间分布特征与配电网络运行约束,提出了一种基于交通流量空间分布的公共充电站优化规划方法。首先建立城市交通流量分布单元模型,构建城市交通流量样本空间,用局部流量密度分析充电站服务范围内交通流量,用分布间距分析总体布局均衡性。然后以每个充电站周围具有较大交通流量密度、充电站站点分布均衡同时最优构建目标函数,结合城市交通流量分布和电动汽车保有量分析充电容量约束,基于充电容量分析电网运行潮流和电压偏移约束,采用聚类算法搜索发现局部流量密度和分布间距峰值,进行优化迭代,实现考虑交通流量的电动汽车充电站优化规划。最后以某规划区域为例,证明了该方法可为电动汽车充电站的优化规划提供依据。     

面向用户需求的电动汽车充电站最优规划模型研究

考虑到用户出行的便捷和充电站运营商的利益,提出一种电动汽车充电站最优规划模型。该模型充分考虑电动汽车用户的出行需求和选择决策行为,同时还给出基于改进的免疫遗传算法的模型求解算法。以某市城区为例,利用MATLAB仿真,验证模型及算法的有效性。研究结果表明,由该模型求得的充电站建设方案能够有效地减少用户充电过程中的绕行距离,缩短耗费的时间,保证充电站的利用率及覆盖率;同时,还能提高充电站运营商的收益。     

Ash-forming elements in four Scandinavian wood species. Part 1: Summer harvest

Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden.     

NEXT GENERATION ENGINEERED MATERIALS FOR ULTRA SUPERCRITICAL STEAM TURBINES

正1 ABSTRACT To reduce the effect of global warming on our climate,the levels of CO2emissions should be reduced.One way to do this is to increase the efficiency of electricity production from fossil fuels.This will in turn reduce the amount of CO2emissions for a given power output.Using US practice for efficiency calculations,then a move from a typical US plant running at 37%efficiency to a 760℃/38.5 MPa(1 400/5 580 psi)plant running at 48%efficiency would reduce CO2emissions by 170kg/MW.hr or 25%.     

Contents in Volume 23,2014

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Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.     

汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied.     

Assessment methods of material ageing using Sdobyrev''s creep rupture model

The physical aspects of the activation energy, in higher and high temperatures, of the metal creep process were examined. The research results of creep-rupture in a uniaxial stress state and the criterion of creep-rupture in biaxial stress states, at two temperatures, are then presented. For these studies creep-rupture, taking case iron as an example the energy and pseudoenergy activation was determined. For complex stress states the criterion of creep-rupture was taken to be Sdobyrev's, i.e. σ_red = σ₁ β + (1 − β)σ_i, where: σ₁-maximal principal stress, σ_i-stress intensity, β-material constant (at variable temperature β = β(T)). The methods of assessment of the material ageing grade are given in percentages of ageing of new material in the following mechanical properties: 1) creep strength in uniaxial stress state, 2) activation energy in uniaxial stress state, 3) criterion creep strength in complex stress states, 4) activation pseudoenergy in complex stress states. The methods 1) and 3) are the relatively simplest because they result from experimental investigations only at nominal temperature of the structure work, however, for methods 2) and 4) it is necessary to perform the experimental investigations at least at two temperatures.     

Production of hydrogen from sewage biosolids in a continuously fed bioreactor: Effect of hydraulic retention time and sparging

Hydrogen was produced from primary sewage biosolids via mesophilic anaerobic fermentation in a continuously fed bioreactor. Prior to fermentation the sewage biosolids were heated to 70 °C for 1 h to inactivate methanogens and during fermentation a cellulose degrading enzyme was added to improve substrate availability. Hydraulic retention times (HRT) of 18, 24, 36 and 48 h were evaluated for the duration of hydrogen production. Without sparging a hydraulic retention time of 24 h resulted in the longest period of hydrogen production (3 days), during which a hydrogen yield of 21.9 L H₂ kg⁻¹ VS added to the bioreactor was achieved. Methods of preventing the decline of hydrogen production during continuous fermentation were evaluated. Of the techniques evaluated using nitrogen gas to sparge the bioreactor contents proved to be more effective than flushing just the headspace of the bioreactor. Sparging at 0.06 L L min⁻¹ successfully prevented a decline in hydrogen production and resulted in a yield of 27.0  L H₂ kg⁻¹ VS added, over a period of greater than 12 days or 12 HRT. The use of sparging also delayed the build up of acetic acid in the bioreactor, suggesting that it serves to inhibit homoacetogenesis and thus maintain hydrogen production.