基于改进蜜獾优化算法的光伏MPPT研究

光伏阵列的输出功率易受外界影响而呈现功率多峰值现象,传统的最大功率追踪算法难以寻得最优功率输出。为了提升光伏发电系统的效率,提出一种改进的蜜獾优化算法作为光伏最大功率点追踪的方法。结合Tent映射,使种群在初始化过程中均匀分布,以增加算法全局寻优能力。在Matlab2018b/Simulink环境下仿真,基于Boost电路验证最大功率的追踪效果,结果显示,该方法在不同工况下,较粒子群算法的MPPT,均具有较好的追踪效果,且改进的HBA算法较HBA本身,追踪时间缩短了0.104 s。     

基于粒子群优化算法的光伏最大功率跟踪

针对光伏发电系统在局部阴影条件下呈现高度非线性、时变不确定性和多个局部功率峰值的特点[1],提出一种粒子群优化和改进的扰动观察法结合的MPPT算法。此算法首先利用粒子群算法来快速寻找最大功率区域,然后改进的扰动观察法精确化最大功率点,克服光伏发电系统最大功率陷于局部最优。建立仿真模型,通过仿真实验验证了这种控制方法能快速找到全局最大功率,具有更加突出的动态响应性能,避免了功率损失,提高光伏发电效率。     

户用型微电网恒功率控制方法的研究

针对光储独立微网中直流母线电压易受光伏发电功率及负载用电功率的波动影响,通过类推V-I下垂控制提出一种功率-电流(P-I)控制策略,用控制系数k来改变与光伏发电输出功率的数学关系,以实现微网的功率平衡,可有效抑制微网直流母线电压的波动。通过建立光伏电池及蓄电池数学模型,分析PV发电输出功率与负荷功率的关系,推导出系数k与光照强度及储能充放电电流之间的关系式,设计了一种P-I控制器。Simulink仿真结果表明,该P-I控制方法能有效地协调控制直流母线功率平衡,有效地提高系统的稳定性。     

基于SG/Simulink的一种改进MPPT算法

针对传统MPPT算法响应速度慢和追踪精度不够理想的特点,分析了光伏电池在不同环境下的输出特性,提出一种改进的变步长扰动观测法,即采用新的自适应步长公式 作为扰动步长,使光伏电池以较大步长快速接近最大功率点,然后以较小步长稳定于最大功率点。在SG/Simulink混合建模仿真平台下进行了仿真,所得结果表明算法可显著提高最大功率点追踪速度与精度。     

太阳能光伏驱动车载散热通风系统

文中设计一种太阳能光伏电池驱动的车载散热通风系统,采用光伏电池、SEPIC变换器、蓄电池和BUCK变换器的并联结构,由一片DSC芯片实现系统的功能控制与能量管理,实现光伏电池驱动车载风扇降温和为汽车蓄电池充电的双重功能。系统通过DSC芯片控制SEPIC变换器来改变光伏电池的负载特性曲线,使得环境因素变化时负载始终与电池外特性曲线相交于最大功率点,实现最大功率追踪;另外DSC芯片实时检测车内温度,控制散热风扇的转速,排出车内热空气,达到控制车内温度的效果;散热风扇运转功率来自光伏发电,且光伏发电多余电能为车载蓄电池充电。该设计提高了车辆的舒适性,具有一定节能减排的效果。通过Simulink仿真和实验验证了该设计的可行性和控制策略的有效性。     

光伏电池输出特性与最大功率点跟踪的仿真分析

根据太阳能光伏电池的等效电路特点,建立了相应的光伏电池组件的仿真模型。该模型可以实现在不同光照强度和温度下光伏组件的输出特性,在此模型基础上研究了光伏组件最大功率追踪方法(MPPT)。在众多最大功率追踪方法中,扰动法有着比较优秀的控制效果。针对最常用的最大功率点跟踪方法-扰动观察法,提出一种改进型的扰动法算法,通过仿真结果和实验证明该方法在一定程度上可解决光伏电池输出非线性的问题,有效避免跟踪偏差,提高光伏电池的输出效率,且动态响应速度快,使光伏系统具有良好的动态和稳态性能。     

光伏电池的自适应占空比扰动MPPT算法研究

环境温度、光照强度和负载等因素对光伏电池的输出特性影响很大,为了提高光伏电池的工作效率,需要准确快速地跟踪光伏电池的最大功率点。在分析了光伏电池的输出特性的基础上,建立了光伏电池的仿真模型;针对传统爬山法的不足,采用了自适应占空比扰动法对最大功率点进行了跟踪控制。给出了上述两种算法的工作原理及设计过程。仿真结果表明:自适应占空比扰动算法跟踪迅速,减少了系统在最大功率点附近的振荡现象,提高了系统的跟踪速度和精度。     

基于变步长电导增量法的光伏最大功率跟踪控制

太阳能光伏发电的最大功率跟踪控制是小型太阳能发电系统中的核心控制之一.针对光伏电池功率曲线的特点,本文在分析最大功率跟踪原理的基础上,提出了基于变步长电导增量法,实现光伏电池最大功率跟踪的优化控制,最大程度的提高光伏电池效率.并通过与定步长算法的仿真对比实验,验证了该算法跟踪迅速,控制精度高和稳定无振荡的特点.     

基于模糊控制算法的光伏电池MPPT设计

介绍了光伏电池的特性,分析了光伏电池最大功率点跟踪（MPPT）的原理,针对光伏电池具有非线性和时滞性的特点,提出了一种模糊控制算法来跟踪光伏电池的最大功率点。仿真结果显示,系统具有良好的控制性能。     

光伏发电系统中最大功率跟踪的研究

讨论了并网太阳能光伏发电系统最大功率跟踪问题-提出了实现最大功率跟踪的方法,并且比较了四种方法优缺点。在分析光伏电池伏安特性的基础上,提出扰动观察法的实现算法,通过比较前后两次功率的大小来决定光伏电池电压扰动的方向,使光伏电池最终达到最大功率点。文章利用Matlab的S-函数构建了光伏电池的仿真模型,实验结果表明,该算法可有效跟踪光伏电池最大功率点,适用于光伏并网逆变系统。     

Experimental Performance of MPPT Algorithm for Photovoltaic Sources Subject to Inhomogeneous Insolation

Photovoltaic (PV) power system performance depends on local irradiance conditions. PV systems are sometimes subject to partial shading, which may produce a nonideal characteristic curve, presenting true and local power maxima in the P -I curve. Traditional maximum power point tracking (MPPT) algorithms can converge to local maximum, which is not the true MPP. In order to solve the problem, this paper investigates the effects of nonuniform solar irradiance distribution on a PV source. An MPPT algorithm that is able to optimize the source instantaneous operating power under nonuniform irradiance is proposed. The ability of the algorithm and its increased performance with respect to traditional algorithms are evaluated by means of experimental tests performed on a real PV power system.     

基于多元优化算法的路径规划

本文提出了一种基于多元优化算法和贝塞尔曲线的启发式智能路径规划方法.该方法通过用贝塞尔曲线描述路径的方法把路径规划问题转化成最优化问题.然后,使用多元优化算法来寻找最优的贝塞尔曲线控制点以获得最优路径.多元优化算法智能搜素个体协同合作交替的对解空间进行全局、局部迭代搜索以找到最优解.多元优化算法的搜索个体（元）按照分工不同可以分为全局元和局部元.在一次迭代中,全局元首先探索整个解空间以找出更优的潜在解区域.然后,局部元在各个潜在解区域进行局部开采以改善解质量.可见,搜索元具有分工不同的多元化特点,多元优化算法也就因此而得名.分工不同的搜索元之间高效的沟通和合作保证了多元优化算法的良好性能.为了评估多元优化算法的性能,我们基于标准测试地图比较了多元优化算法与其它三种经典启发式智能路径规划算法.结果表明,我们提出的方法在最优性,稳定性和有效性上方面优于其它方法.     

A lossless image compression algorithm using variable block sizesegmentation

The redundancy in digital image representation can be classified into two categories: local and global. In this paper, we present an analysis of two image characteristics that give rise to local and global redundancy in image representation. Based on this study, we propose a lossless image compression scheme that exploits redundancy both at local and global levels in order to obtain maximum compression efficiency. The proposed algorithm segments the image into variable size blocks and encodes them depending on the characteristics exhibited by the pixels within the block. The proposed algorithm is implemented in software and its performance is better than other lossless compression schemes such as the Huffman, the arithmetic, the Lempel-Ziv and the JPEG.     

基于光谱角背景纯化的高光谱异常检测算法

为了解决利用高光谱图像进行异常检测时结果不准确、虚警率较高的问题,提出了一种基于光谱角背景纯化的异常检测算法。该算法以局部RX算法为基础,根据光谱角距离分离出内外窗口间背景像元中的异常成分,得到纯化后的背景像元,然后进行异常检测。为验证算法的有效性,选取了两组机载可见光/红外光成像光谱仪真实高光谱数据进行仿真实验,并与经典的全局RX、局部RX算法进行对比。结果表明,与局部RX算法相比,该算法在两组数据下的曲线下面积分别提高了0.0317和0.0053。这些结果为下一步的研究方向提供了参考。     

Multijunction solar cell design revisited: disruption of current matching by atmospheric absorption bands

This paper re‐examines the impact of atmospheric absorption bands on series‐connected multijunction cell design, motivated by the numerous local efficiency maxima that appear as the number of junctions is increased. Some of the local maxima are related to the bottom subcell bandgap and are already well understood: As the bottom subcell bandgap is varied, a local efficiency maximum is produced wherever the bottom cell bandgap crosses an atmospheric absorption band. The optimal cell designs at these local maxima are generally current matched, such that all subcells have nearly the same short‐circuit current. Here, we systematically describe additional local maxima that occur wherever an upper subcell bandgap encounters an atmospheric absorption band. These local maxima are not current matched and become more prevalent as the number of junctions increases, complicating the solution space for five‐junction and six‐junction designs. A systematic framework for describing this complexity is developed, and implications for numerical convergence are discussed. Copyright © 2017 John Wiley & Sons, Ltd.     

基于演化密码理论的Koblitz安全曲线选择研究及对美国NIST参数验证

Elliptic curve cryptography is one of the most important public key cryptography. The Koblitz Curve is a special kind of elliptic curve in ECC and its security mainly depends on the base field. Based on Evolutionary Cryptography theory, which becomes a principal concept for cryptography design and cryptanalysis, we propose a new algorithm for secure EC generation based on Ant Colony Optimization (ACO) to accelerate the search process of safe base field. We preliminarily deal with secure Koblitz curve selecting over the field F(2800). Experiments show that the base field and base point of secure curves generated by ant colony algorithm have gone beyond the parameter range of Koblitz curves recommended by NIST. We can present many new secure Koblitz curves, including base field and base point, which are not recommended by NIST. The maximum size of our secure Koblitz curve has gone beyond 700bit. The algorithm in this paper follows the same cryptography criteria recommended by the ANSI. So, it can resist current attacks. Theoretical analysis and experimental results prove that the new algorithm is effective and successful, and it is the first successful practice of Evolutionary Cryptography theory in public cryptography research.     

显微镜的快速自动对焦算法

针对平面样品的大规模显微图像采集,提出了一种基于预测的快速自动对焦算法.首先,利用相邻图像的对焦位置估计当前图像的对焦位置,并在其附近做微小调整即可得到最佳对焦位置,从而避免对焦评价曲线的多峰干扰.其次,利用阈值分割方法选择对焦窗口以消除背景干扰,使对焦评价函数满足无偏性.该算法大大减少了自动对焦所需要采集的图像数量,对焦速度、精度以及鲁棒性均有明显的提高.     

局部阴影下光伏阵列最大功率点跟踪算法的研究

在局部阴影条件下,光伏阵列的功率-电压（P-V）特性曲线呈现多峰现象,传统的最大功率点跟踪方法容易受困于局部最大功率点,造成输出功率的损失。提出了基于布谷鸟搜索算法（cuckoo search,CS）的MPPT新方法,利用Lévy飞行搜索机制快速、有效的跳出局部最优的束缚,完成对全局最大功率点的跟踪。仿真和实验验证了该方法的可行性和有效性。     

Detection of curved edges at subpixel accuracy using deformablemodels

One approach to the detection of curves at subpixel accuracy involves the reconstruction of such features from subpixel edge data points. A new technique is presented for reconstructing and segmenting curves with subpixel accuracy using deformable models. A curve is represented as a set of interconnected Hermite splines forming a snake generated from the subpixel edge information that minimises the global energy functional integral over the set. While previous work on the minimisation was mostly based on the Euler-Lagrange transformation, the authors use the finite element method to solve the energy minimisation equation. The advantages of this approach over the Euler-Lagrange transformation approach are that the method is straightforward, leads to positive m-diagonal symmetric matrices, and has the ability to cope with irregular geometries such as junctions and corners. The energy functional integral solved using this method can also be used to segment the features by searching for the location of the maxima of the first derivative of the energy over the elementary curve set     

Connectivity of projected high dimensional data charts on one-dimensional curves

We propose a principal curve tracing algorithm, which uses the gradient and the Hessian of a given density estimate. Curve definition requires the local smoothness of data density and is based on the concept of subspace local maxima. Tracing of the curve is handled through the leading eigenvector where fixed step updates are used. We also propose an image segmentation algorithm based on the original idea and show the effectiveness of the proposed algorithm on a Brainbow dataset. Lastly, we showed a simple approach to define connectivity in complex topologies, by providing a tree representation for the bifurcating synthetic data.