多功能光伏发电系统仿真设计

提供一种基于Matlab/Simulink的多功能光伏(PV)发电系统仿真设计方法,既可用于系统运行分析和控制器设计,又可通过dSpace将其用于实验室系统.并对系统运行模式进行分析,采用stateflow进行运行模式控制;给出光伏逆变器和蓄电池充放电控制方法,以及它们在Matlab/Simulink中的实现方式。该仿真方法的应用可促进分布式发电的实用化进程.     

基于迟滞神经网络的风速时间序列预测

为了改善风速时间序列的预测性能,提出了一种基于迟滞神经网络的预测方法.通过改变神经元激励函数的方式将迟滞特性引入神经网络中,以增强历史输入对当前响应的影响,从而提高有用信息的利用率,提高风速时间序列的预测性能;借助于相空间重构理论构造风速预测训练样本,采用梯度下降法对网络权值进行训练,利用遗传算法对迟滞参数进行优化.仿真结果表明:与传统神经网络及ARMA模型等方法相比,迟滞神经网络能够有效减小风速时间序列的预测误差,提高预测性能.     

大功率LED路灯电源系统中PFC模块的设计与实现

为了控制谐渡对电网的污染,电源中有必要增加PFC模块,采用有源PFC工作原理实现了一种升压型变换器模块,设计完成由交流电压90~265 V输入到稳定的400 V直流输出,所采用的核心控制芯片为L6561.实验结果表明:该变换器的输出电压稳定度高,功率因数达到0.94以上,能够减少整个电源系统的损耗.     

基于增量学习思想的改进AdaBoost 建模方法

针对软测量建模的特点以及建模过程中存在的主要问题,提出了基于 AdaBoost RT 集成学习方法的软测量建模方法,并根据 AdaBoost RT 算法固有的不足和软测量模型在线更新所面临的困难,提出了自适应修改阈值 和增添增量学习性能的改进方法.使用该建模方法对宝钢300 t LF 精炼炉建立钢水温度软测量模型,并使用实际生产数据对模型进行了检验.检验结果表明,该模型具有较好的预测精度,能够很好地实现在线更新.     

基于GaN全桥LLC谐振变换器交错并联系统的损耗分析

为提高全桥LLC谐振变换器交错并联(FBLLC-SP)系统的效率,且使其理论损耗与实际运行损耗更贴近,对比Cascode型GaN HEMT向系统引入单体增强型GaN HEMT,并将其寄生参数引入到损耗模型中,建立了一种适用于单移相(SPS)开环控制和三移相(TPS)双闭环控制的FBLLC-SP系统精准损耗模型;给出最佳死区时间计算方法,并分析了FBLLC-SP系统在单移相(SPS)开环控制下的理论损耗,提出了不同模态GaN HEMT的暂态损耗和各种通态损耗的精准计算方法;搭建了FBLLC-SP系统损耗模型仿真系统。实验结果表明:本文损耗模型的损耗值比系统实际运行损耗最多高约0.6%,说明本文建立的精细化损耗模型可用于分析系统的实际运行损耗。     

Author index

Based on the generalized Hamiltonian system theory, a new approach to dissipative Hamiltonian realization of nonlinear differential algebraic system is proposed in this paper, and a simple control strategy to stabilize the dynamic system without linearization treatment is designed. The new approach is applied to the nonlinear excitation controller design of structure preserving multi-machine power system. Simulation results demonstrate that the approach proposed in this paper is correct, and the control strategy designed is effective.     

Nonlinear guidance techniques for agile missiles

The paper presents new approaches to the guidance of agile missiles. They are based on nonlinear discontinuous control techniques applied to the generation of guidance laws capable of taking advantage of the vehicle's post-stall capabilities. Agility and maneuverability requirements imply a higher bandwidth and robustness for the guidance loop, which are addressed by a variable structure controller format. Formal stability considerations are presented, and the guidance structures are validated using nonlinear simulation.     

Electrospun fibrous active bimetallic electrocatalyst for hydrogen evolution

Fabricating earth-abundant bifunctional water splitting electrocatalysts with high efficiencies to replace noble metal-based Pt and IrO₂ catalysts is in great demand for the development of clean energy conversion technologies. Molybdenum disulfide (MoS₂) nanostructures have attracted much attention as promising material for hydrogen evolution reaction (HER). The production of hydrogen gas by help of potential efficient earth abundant metal oxides, and stable electrolysis seems a promising for hydrogen evolution reaction pathway in 1 M potassium hydroxide electrolyte media is a hot research topic in the field for clean energy conversion, renewable energies and storage. Here we propose asystem composed NiO nanostructures and MoS₂ deposited on (MoS₂@NiO). Here, by hydrothermal method NiO prepared and MoS₂@NiO by an electrospinning technique complex, can be used as catalyst to produce a large amount of hydrogen gas bubbles. The NiO nanostructures composite having highest synergistic behavior fully and covered by the MoS₂. For the MoS₂@NiO nano composite catalyst, experiment applied in 1 M KOH for the production of hydrogen evolution reaction which exhibits distinct properties from the bulk material. Overpotential values recorded low 406 mV and current density 10 mA cm⁻² measured. Co-catalysts characterized by using different techniques for deep study as scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Owing to their unique structure, as-prepared nanocomposite exhibited enhanced catalytic performance for HER due to high electroactive surface area and swift electron transfer kinetics. Based on the HER polarization curves at low potential electrochemical to examine the effects of intercalants HER catalytic efficiency. Our findings establish low Tafel slope (44 mV/decade) and the catalyst stable for at least 13 h. This simple exploitation of MoS₂@NiO composite catalysts depending on the intended application of their electrochemistry.     

Influence of process parameters on enhanced hydrogen evolution from alcoholysis of sodium borohydride with a boric acid catalyst

The hydrogen evolution via alcoholysis reaction of sodium borohydride with an H₃BO₃ catalyst was carried out for the first time. In the process of methanol and NaBH₄ (NaBH₄-MR), the effects of the H₃BO₃ and NaBH₄ concentration, and temperature parameters were examined and evaluated. The hydrogen yields by the NaBH₄-MR, NaBH₄ ethanolysis (NaBH₄-ER) and NaBH₄ hydrolysis reactions (NaBH₄-HR) with 0.2 M H₃BO₃ catalyst are 99, 62, and 88% compared to the theoretical hydrogen yield, respectively. The completion times of the NaBH₄-MR using the H₃BO₃ concentrations of 0.2, 0.4, 0.5, 1 M, and saturated acid solution were about 50, 15, 10, 2 and 1 min, respectively. The hydrogen yields obtained with 50, 15, 10, 2, and 1 min for the same acid concentration values were about 100% compared to the theoretical hydrogen value. By increasing the H₃BO₃ concentration from 0.2 M to the saturated H₃BO₃ concentration, the completion time of this NaBH₄-MR process was reduced by approximately 50 times, resulting in a significant result. The activation energy (Ea) of the NaBH₄-MR with the H₃BO₃ catalyst was 57.3 kJ/mol.