基于MEEMD-QUATRE-BILSTM的短期光伏出力区间预测

提出一种基于改进集成经验模态分解（MEEMD）和拟仿射变换（QUATRE）优化双向长短期记忆神经网络（BILSTM）的光伏出力区间预测模型。通过主成分分析法（PCA）对时间序列进行降维处理，利用K-均值算法将降维数据分成3种类型气象数据；然后采用MEEMD对每类光伏出力序列进行分解，将其输入QUATRE优化BILSTM神经网络和核密度估计算法（KDE）联合构建的短期光伏出力区间预测模型。最后基于宁夏光伏电站实例仿真评估模型区间预测性能，实验结果表明该模型可生成高水平光伏预测区间，能够为电力系统经济稳定运行提供可靠的决策保障。     

基于CNN-VMD-PCA特征融合的光伏发电功率预测研究

为了较为准确地预测光伏发电功率，提出一种特征融合的功率预测模型。模型首先使用一维卷积神经网络(1-dimensional convolutional neural network, 1D-CNN)提取光伏光电数据深度特征，然后用变分模态分解方法(Variational mode decomposition, VMD)分解数据原特征，再把分解后的特征和深度特征融合，用主成分分析法(Principal component analysis, PCA)提取融合后特征的主成分，最后用Xgboost(Extreme gradient boost, Xgboost)模型进行功率预测。根据对所提模型的实测评估，并与其他预测模型对比，得出基于CNN-VMD-PCA特征融合的预测模型具有较高预测精度，其拟合优度达0.932,能够得到更可靠的功率预测结果。     

基于CEEMD-CNN-BiGRU-RF模型的短期风电功率预测

风电功率的准确预测对电网的安全运行和经济调度起着重要作用,为进一步提高风电功率的预测精度,文章提出了一种基于CEEMD-CNN-BiGRU-RF模型的短期风电功率预测模型。首先,利用完全集成经验模态分解(CEEMD)对风电功率时间序列进行模态分解;其次,对分解的各个风电功率时间序列利用卷积神经网络(CNN)进行特征提取;再次,建立双向门控循环单元(Bi GRU)模型对各个风电功率时间序列进行预测,叠加各个分量的预测值;最后,对误差进行进一步分析与预测,利用随机森林(RF)进行误差修正,得到最终的风电功率预测值。实验仿真表明,该模型的预测效果明显优于传统模型,模型的平均绝对百分比误差(MAPE)仅为2.09%。     

基于EVMD和布谷鸟算法的短期风功率区间预测

为提高短期风功率预测精度和预测的可控性,提出一种基于能量差优化变分模态分解和布谷鸟优化组合神经网络的短期风功率预测模型。采用能量差优化变分模态分解（EVMD）的模态数,将EVMD用于短期风功率分解,基于EVMD分解序列的不同模态特点,对非线性序列采用布谷鸟优化反向传播神经网络（CS-BPNN）,对平稳序列采用自回归滑动平均模型（ARMA）,并重构加权得到点预测值,并基于EVMD分解所丢失的序列信息构建核密度估计,在点预测模型的基础上,进行风功率的区间预测。将所提预测方法用于澳大利亚风电场的实际算例,实验结果表明,该方法可提高短期风功率预测的准确性。     

组合两步分解和ARIMA-LSTM的短期风速预测研究

为提高风速序列预测精度,提出一种基于两步分解的短期风速组合预测模型,首先使用鲁棒经验模态分解（REMD）将风速数据分解为不同频率的子序列,然后将REMD分解得到的高频模态分量使用小波包分解（WPD）进行第二步分解,降低风速序列不稳定性,提高其可预测性。其次对分解得到的高频子序列建立长短期记忆神经网络（LSTM）预测模型,低频子序列建立差分自回归移动平均模型（ARIMA）预测模型。最后叠加子序列预测结果得到风速预测结果。通过两组不同风速数据集的实验对该模型的性能进行科学评估,模型预测结果的平均绝对误差分别为0.3026、0.1255;均方根误差分别为0.498、0.1607。与其他几种对比预测模型相比,验证该模型具有一定的优越性。     

基于CCNN的光伏发电功率预测

高精度光伏功率预测在光伏并网、电网安全稳定运行中起着重要作用。为获得可靠的预测功率,本文提出了一种基于因果卷积神经网络（Causal Convolutional Neural Network,CCNN）的预测模型。首先,将处理后的特征数据输入到因果卷积神经网络,在每一卷积层中,利用LSTM网络输入门对输入数据去噪,选出重要信息,而后经过1×1卷积核实现信息整合,同时降低运算复杂度,从而构建出CCNN预测模型。最后,采用巴西某发电厂真实数据对模型进行验证,并与人工神经网络（ANN）、LSTM和卷积神经网络（CNN）模型进行对比。结果表明,该方法可以很好地反映时序信息的动态特性,且预测精度优于对照模型,具有一定的实用价值。     

双模式分解CNN-LSTM集成的短期风速预测模型

为提高短期风速的预测精度,提出一种基于双模式分解、双通道卷积神经网络（CNN）和长短期记忆神经网络（LSTM）的组合预测模型以提高预测精度。首先,对经过PAM方法聚类后的风速时间序列利用奇异谱分解（SSD）和变分模态分解（VMD）2种信号分解方法进行分解,获得2类多尺度分量。不同模式的多尺度分量可降低原始风速的复杂度和非平稳性,实现不同模式模态分量规律的互补;其次,将2种分解方法得到的风速子序列合并为一个矩阵,输入到双通道CNN进行波形特征深度提取;最后,采用LSTM建立历史风速时序的时间依赖关系,在时空相关性分析的基础上得到最终风速预测结果。实验结果表明,基于双模式分解-双通道CNN-LSTM的组合预测模型可有效提高风速短期预测的精度。     

基于小波PLS电站锅炉NO_x自适应预测

电站锅炉机理复杂,很难建立能够用于NOx实时预测和控制的机理模型。为此,将小波分析与偏最小二乘回归(Partial Least Squares,PLS)算法相结合,提出基于小波PLS的NOx排放预测模型。该方法可较好地实现数据去噪和样本预处理,并可对输入因素进行成分提取,对因变量NOx有较好的解释能力,通过对样本自动筛选,实现预测模型的自适应更新。采用京隆电厂1#机组600 MW锅炉的实际运行数据对该算法进行了验证,将其与神经网络预测模型进行了对比,结果显示此方法预测精度更高,效果更好。     

基于EEMD和BP神经网络的短期光伏功率预测模型

摘要： 为了实现对并网型光伏电站调度,提出了一种基于集合经验模态能分解（EEMD）与BP神经网络的短期光伏出力的组合预测模型。利用集合经验模态分解将光伏出力序列分解,得到本征模函数分量IMF和剩余分量Res,降低序列的非平稳性。采用游程检验法优化因IMF分量数量多造成的建模过程复杂的问题,针对优化后的分量分别建立相应的BP神经网络预测模型。利用该方法对额定容量为40 kW的光伏系统进行预测,并与EMD-BP神经网络和传统的BP神经网络模型进行比较分析。结果表明,所提出的方法有效地提高了预测精度。     

基于改进VMD-BPNN的光伏功率预测

针对光伏发电预测模型准确率低的问题，构建了基于变分模态分解-反向传播神经网络(VMD-BPNN)的光伏功率预测模型。对光伏发电数据进行变分模态分解得到不同特征数据，解决了数据的随机性和波动性问题。再采用K-means聚类方法对不同特征数据进行聚类，提高模型的泛化能力。通过集成学习bagging的方法对BPNN进行增强，以达到提高光伏功率预测模型整体稳定性的目的。根据RMSE和NRMSE误差标准进行测试，测试结果表明，基于VMD-BPNN预测模型的NRMSE平均值2.77%,RMSE平均值为2.22%。     

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.     

Wind power for pumping: The development of the ITP windpump

Water pumping has been one of the main applications for wind power in the past and despite the spread of mains-electric pumps, more than a million windpumps remain in regular use. This paper reviews the general technical and economic requirements for pumping water using wind energy and by way of example gives an overview of the development of the new ITP wind-pump. It then considers the future prospects for this kind of technology.     

Methods of creating solar-reflective nonwhite surfaces and their application to residential roofing materials

We describe methods for creating solar-reflective nonwhite surfaces and their application to a wide variety of residential roofing materials, including metal, clay tile, concrete tile, wood, and asphalt shingle. Reflectance in the near-infrared (NIR) spectrum (0.7–2.5 μm) is maximized by coloring a topcoat with pigments that weakly absorb and (optionally) strongly backscatter NIR radiation, and by adding an NIR-reflective basecoat (e.g., one colored with titanium dioxide rutile white) if both the topcoat and the substrate weakly reflect NIR radiation. Coated steel and glazed clay-tile roofing products achieved NIR reflectances of up to 0.50 and 0.75, respectively, using only cool topcoats. Gray-cement concrete tiles achieved NIR reflectances as high as 0.60 with coatings colored by NIR-scattering pigments. Such tiles could attain NIR reflectances of up to 0.85 by overlaying a white basecoat with a topcoat colored by NIR-transparent organic pigments. Granule-surfaced asphalt shingles achieved NIR reflectances as high as 0.45 when the granules were covered with a white basecoat and a cool color topcoat.     

Thermal decay of an initially hot isothermal water body with application to thermal energy storage

The thermal decay of an initially hot isothermal water body contained in a tank was studied. Analytical solutions (including a group-theoretic solution) were obtained for the one-dimensional heat conduction equation with heat loss from the sides of the tank. The convective heat transfer coefficient was assumed not to be constant over the surface of the tank but to vary with space and time. A very good agreement was obtained between the group-theoretic solution and a numerical solution using the Crank-Nicholson finite difference scheme. The analytical results are discussed in terms of the underlying physical mechanisms.     

秸秆燃烧中温度对钾转化与释放的影响

通过对稻秆原料进行常规特性分析和EDX元素含量分析,发现钾在稻秆无机元素中占有重要地位。参考原料化学分馏法和土壤中钾的分类与测试方法,给出了对生物质原料及其燃烧产物中钾的定性与定量简易方法。通过程序控温型固定床对稻秆先进行缓慢氧化,然后以100℃为间隔从400～900℃进行成灰,并分别测试其成灰率、有效钾和全钾的份额。结合稻秆原料及其灰中钾的份额分析,进行了稻秆灰中有效钾转化与释放的计算,发现有效钾在700～800℃之间有快速的释放和形态转变。稻秆灰的XRD分析结果表明秸秆灰中钾主要以KCl、K_2SO_4形式存在,得到了钾以盐的形式进行转化与释放的机理。该文中燃烧温度对钾转化与释放的影响规律对设计秸秆电厂时的炉型选择和燃烧参数确定有一定参考价值。     

Exergetic analysis of solid oxide fuel cell and biomass gasification integration with heat pipes

This paper presents an exergetic analysis of a combined heat and power (CHP) system, integrating a near-atmospheric solid oxide fuel cell (SOFC) with an allothermal biomass fluidised bed steam gasification process. The gasification heat requirement is supplied to the fluidised bed from the SOFC stack through high-temperature sodium heat pipes. The CHP system was modelled in AspenPlus™ software including sub-models for the gasification, SOFC, gas cleaning and heat pipes. For an average current density of 3000 A m⁻² the proposed system would consume 90 kg h⁻¹ biomass producing 170 kW_e net power with a system exergetic efficiency of 36%, out of which 34% are electrical.