计及分布式光伏发电的分时电价模型研究

针对分布式新能源发电在配电网的大量接入,提出了一种计及分布式光伏发电的分时电价模型,通过模糊隶属函数对等效负荷曲线进行时段划分,基于消费者心理学建立用户响应曲线,并在考虑用户舒适度的情况下采用遗传算法进行求解。算例分析表明,分时电价可有效地进行削峰填谷,提高等效负荷曲线的负荷率,并兼顾到用户舒适度,说明了所提出的分时电价模型具有优越性和可实施性。     

考虑广泛负荷聚合商无功调节优先权的调度决策模型

针对柔性负荷、分布式储能和分布式电源等负荷聚合商在参与电力市场调度中存在的问题,整合各类分布式资源构成广泛负荷聚合商,建立考虑无功调节优先权的广泛负荷聚合商参与电力市场调度的决策模型。首先,考虑不同分布式资源在参与电网调度时的无功可调节水平、无功调节可信度、调节经济性与有功支撑水平方面的特性,基于熵权法建立考虑无功优先权的调度评估模型;然后,以广泛负荷聚合商参与电力市场调度的收益最大为目标建立调度决策模型及其求解方法;最后,通过算例仿真表明该文提出的调度决策模型的有效性和经济性。     

基于Adaline神经网络参数辨识的含DG配电网的电压稳定性分析

提出了一种基于Adaline神经网络参数辨识来研究含有分布式电源配电网电压稳定性的方法。依据戴维南等值理论,将含有分布式电源的配电网络等值为3节点系统,在该等值系统的基础上提出了一种新的电压稳定性指标;将Adaline神经网络用于戴维南等值系统的参数辨识中,通过测量单元采集到的电压和电流相量对系统进行训练,得到戴维南等值系统的电势及阻抗,从而对含分布式电源的配电网络进行电压稳定性评估。结合IEEE33节点系统的仿真,对不含分布式电源和含分布式电源的配电网络在不同负荷水平下的电压稳定性进行了分析。所提出的电压稳定性指标、等值系统参数辨识方法及配电网电压稳定性分析为评估分布式电源对配电网电压稳定性的影响提供了基础。     

计及分布式电源无功出力的ISFLA算法配电网无功优化

摘要： 针对含分布式电源的配电网无功优化的特点,将分布式电源的无功调节能力和传统无功调压手段相结合,研究了考虑分布式电源无功调节能力的配电网无功优化模型和算法。针对分布式电源出力的随机性,采用场景概率的决策方法计算分布式电源的出力情况和对应无功功率极限,以网损最小和节点电压越限惩罚作为目标函数。提出了基于免疫蛙跳算法（ISFLA）的无功优化算法,该算法通过在混合蛙跳算法（SFLA）的算法框架中引入克隆选择算法（CSA）,在蛙群混合后选择较优解进行克隆、变异和选择,克服了SFLA局部搜索能力弱的特点。利用改进IEEE33节点系统作为算例仿真分析,结果验证了模型及算法的有效性。     

基于APDE算法的配电网分布式电源承载力评估

针对分布式电源接入配电网装机容量问题,提出一种基于自适应扰动差分进化算法（APDE）的配电网分布式电源最大承载能力评估方法。首先建立包含有载调压变压器及静止无功补偿器的配电网模型,并优化系统潮流与注入功率的关系表达式,通过考虑分布式电源及负荷的不确定性,建立基于机会约束规划下的源荷不确定性配电网分布式电源最大承载力评估模型;然后对差分进化算法进行改进,形成APDE算法以求解模型;最后基于IEEE-33节点配电系统对所建配电网模型进行分析,验证其满足电力系统分析需求,并进一步对所提配电网分布式电源承载力评估方法进行分析,通过与相关算法比较,证明了所建模型的可行性和改进方法的有效性。     

含可响应分布式电源的智慧能源配网多目标优化调度

分布式电源增加了配电网的灵活性,但同时也给配网调度带来一定挑战。文章针对含有可响应分布式电源的配网多目标优化调度进行研究。首先分析了居民智慧能源的特征以及居民用户、分布式电源、运行商三者的关系;然后考虑了分布式电源的不确定性,建立了风机和光伏的出力模型,从经济性、环保和配网可靠性角度建立了居民智慧能源配网多目标调度优化模型;针对配网负荷多样化的特点,提出了负荷因数模型,计及到多目标优化模型中;最后利用决策算法求解该模型,并在IEEE33节点系统中进行仿真,说明了所提模型和算法的有效性。     

考虑风光荷不确定性的随机生产模拟

为研究新能源出力随机性、负荷预测误差等不确定因素的影响,该文中将蒙特卡洛模拟与解析法相结合,建立一套考虑风、光、荷不确定性的随机生产模拟模型和算法。首先对风电、光伏、负荷时序出力的预测误差进行抽样,并经计算获得净负荷曲线的累积概率和频率分布;然后通过求解机组的多状态模型和条件概率,完成相应的卷积运算,并综合运算结果计算出火电机组的生产成本和系统可靠性指标。最后算例比较分析负荷及新能源不确定性对系统技术经济指标的影响,为含新能源的电力系统随机生产模拟研究提供了参考。     

考虑感应电动机稳定约束的城市综合能源系统暂态过程优化控制模型

针对由可再生能源或清洁能源供能的城市综合能源系统中的感应电动机,在多能源形式的供能和负荷波动及不确定性条件下的运行稳定性问题,提出了一种考虑综合能源系统中多种类可再生电源及多能源负荷协调的感应电动机临界转矩优化。首先建立含综合能源的电网广义负荷模型;其次基于戴维南等值电路对感应电动机负荷的外部网络进行等效;最后推导感应电动机转矩方程,进而提出城市电网感应电动机暂态过程优化方法。以某城市综合能源网为例,采用BPA软件建立城市综合能源系统等值模型,仿真结果验证了文章所提方法的有效性。     

基于原对偶内点法的发输电系统可靠性评估交流潮流分析法

电力系统可靠性评估对于精度的要求随着新能源接入电网不断提高。传统的发输电系统可靠性评估在状态校正过程中采用基于直流潮流的最小切负荷模型,该模型存在不能考虑系统电压和无功功率的局限。利用原对偶内点法在可靠性评估中实现了基于交流潮流的有功无功综合优化状态校正模型。该模型通过非线性规划综合考虑系统有功无功关联、网损、节点电压及潮流约束等因素。为了解决非线性规划中计算量大和收敛性的问题,还提出了一种改进的基于交流潮流有功无功解耦的状态校正模型。对IEEE-RTS79系统与2012年海南电网进行可靠性评估,结果证明了所提出算法的精确性和有效性。该方法有望应用于更精确地对含新能源发输电系统进行可靠性评估。     

基于能量预测的光伏微网储能系统控制策略

以光伏微网储能系统为研究对象,提出一种融入光伏发电与负荷预测技术的储能系统模糊控制策略。该方案考虑了光伏输出功率随天气条件变化的随机性,建立了光伏短期功率预测最小二乘支持向量机(LSSVM)模型;考虑电力负荷影响因素的多样性与不确定性,基于灰色关联度(GRA)建立了电力负荷LS-SVM预测模型;考虑建立在偏远地区的微网系统,因分布式电源上网造成电能质量下降和电能传输过程的浪费,建立储能系统模糊控制策略,以确定电能最优分配及就地消纳,以保证系统能源利用效率。根据算例分析表明,该控制方案不仅可准确预测光伏微网能量,而且可提高储能系统运行效率,降低电能传输过程中线路损耗以及对电网电能质量的影响。     

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.     

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.     

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.