风能转换系统的建模与复合控制研究

在大型风电项目建设之前进行建模和仿真具有重要的指导意义,结合空气动力学子系统、机械传动链子系统和简化的电磁子系统,构建了永磁同步风力发电系统模型,作为研究控制性能的被控对象。风速的随机性和不确定性会导致风电场输出功率的随机波动,甚至影响电网的安全运行和电能质量,传统控制手段难以实现有效的控制,需要先进的控制手段。提出构建复合控制器,以小脑模型神经网络进行模型逼近,构造前馈控制,以传统PID为反馈控制的控制方式,给出了具体的控制算法。通过仿真可见,所建模型有助于研究风电系统的功率特性和跟踪性能,将滑模控制应用于所构建的风力发电系统中,能实现良好的功率跟踪,能够确保最大风能捕获。     

直驱永磁风电系统能量成形与最大风能捕获

针对风速多变及外界干扰情况下风电系统出现的风能利用率低、鲁棒性差及安全可靠性差等问题,提出了一种基于能量成形的直驱永磁风电系统最大风能捕获算法.该算法采用能量成形及端口受控哈密顿(PCH)系统方法,从能量平衡的角度,建立永磁发电机(PMSG) PCH系统的非线性模型,设计了PCH系统反馈控制器.通过基于PCH系统控制器和H∞控制器的叠加反馈,设计出能跟踪最佳转矩且具有扰动抑制的PCH系统H∞控制器.实验结果表明,该控制策略实现了风电系统的变速恒频运行、最大风能利用,验证了理论模型和控制策略的正确性、可行性.     

基于灰色预测的永磁同步电动机速度控制

本文针对永磁同步电动机非线性动态数学模型，采用直接反馈线性化控制，建立了闭环系统的输入-输出模型，通过线性化模型来设计控制器，该方法简单适用；同时，为了克服此反馈线性化控制对模型要求精确化这一不足，提出了基于灰色理论的不确定预测器，它能在线预测永磁同步电机的不确定因素并相应的调整反馈线性化控制法则，从而提高了系统的动态性能。仿真与实验结果表明，该方法对永磁同步电机速度控制具有很好的跟踪性能和鲁棒性能。     

基于双PWM变换器的永磁直驱风电系统控制策略研究

针对基于双PWM变换器的永磁直驱风电系统的控制问题,对该风电系统电机侧变换器、电网侧变换器的控制策略进行了详细的分析,提出了一种桨距角控制策略,并基于Matlab/Simulink对永磁直驱风电系统进行了仿真。仿真结果表明,永磁直驱风电系统能够在不同风速下稳定运行,在额定风速以下可实现风能的最大功率跟踪,在额定风速以上通过桨距角控制能将风机系统的功率输出限制在额定值附近。研究结果验证了所提出的桨距控制策略的可行性。     

垂直轴永磁直驱风力发电系统MPPT仿真研究

选取分布式中小功率垂直轴风力发电机为应用对象,详细阐述了风力机模型、永磁同步发电机(PMSG)模型、空间矢量脉宽调制(SVPWM)技术以及基于最佳叶尖速比(TSR)的最大功率跟踪控制(MPPT)原理,给出了基于Matlab/Simulink仿真的垂直轴永磁直驱风力发电系统模型。通过对在稳定风速和动态风速下的仿真结果分析,验证了搭建的风力发电系统能很好的完成最佳转速的调节,实现最大风能捕获,为垂直轴风力发电系统MPPT控制算法的进一步研究构建基础性的平台。     

直驱永磁同步风力发电系统的研究

本文首先介绍了风力机的特性。然后,介绍了直驱永磁同步风力发电系统的组成及控制策略,通过对三相交错并联Boost变换器占空比控制实现最大功率跟踪,对网侧电流的跟踪闭环控制实现单位功率因数并网运行。最后,基于MATLAB/Simulink搭建了系统最大功率跟踪控制仿真模型进行仿真研究,并通过实验验证了系统控制策略的可行性和正确性。     

数控机床直线同步电动机磁悬浮系统反馈线性化控制的研究

由于在数控机床直线同步电动机磁悬浮系统中,直轴电流、悬浮高度与水平速度之间存在非线性耦合,以及负载扰动等不确定因素,会对控制系统产生诸多不利影响。针对该问题,提出了一种新型解耦控制方法。建立可控励磁磁悬浮直线同步电动机(controllable excitation linear magnetic suspension synchronous motor, CELMSSM)的数学模型;通过选取适当的状态变量得到该电动机的仿射非线性模型;在传统电流控制的基础上,利用非线性系统的微分几何理论,通过坐标变换与状态反馈,将电动机仿射非线性模型解耦线性化为直轴电流子系统、水平速度子系统以及悬浮高度子系统的3个可独立控制的线性子系统;根据最优极点配置法设计系统的控制规律,从而实现可控励磁磁悬浮直线同步电动机的动态解耦控制。最后,对控制系统进行仿真研究,结果表明通过反馈线性化控制与传统PI控制仿真对比,所提出的控制策略可使系统的动、静态性能得到显著增强。     

风电机组控制系统滤波器的设计与实现

根据某公司2 MW风电机组主控系统开发项目,进行风电机组控制系统滤波器的仿真设计与实现研究:基于MATLAB平台的m语言,设计适合风力发电机组控制系统使用的滤波器以配合控制系统运行,并获得最大风能转换效率以提高机组的经济效益。从风电机组控制系统网络拓扑图、控制策略出发,引出滤波器在整个控制策略中的重要性;通过滤波器的仿真验证,研究滤波器频域参数对滤波器性能的影响。为风电机组主控系统滤波器设计和开发提供参考。     

并网型直驱式风电机组的仿真分析

分析永磁直驱风电机组的优点并建立各部分的数学模型,根据变流器的数学模型。提出变流器机侧和网侧的控制策略,能够实现风电机组有功功率和无功功率的独立控制,获得较好的电能质量;利用仿真软件MATLAB／SIMULINK建立永磁直驱风电机组的模型,仿真了机组在风速阶跃变化时的运行时情况,仿真结果验证了模型的正确性。     

永磁直驱风电系统建模及其机电暂态模型参数辨识

针对基于双脉宽调制(PWM)变换器的永磁直驱风电系统的运行特性,分析了风力机特性、电机侧变换器和电网侧变换器的控制策略,利用Matlab/Simulink建立了反映电力电子开关动作的永磁直驱风电系统详细模型,并在此基础上根据同步电机3阶暂态模型,建立了直驱风机的机电暂态数学模型,采用粒子群算法(PSO)对模型进行了参数辨识。仿真结果表明,该详细模型能够描述永磁直驱风电系统对不同风速的响应,实现风能的最大功率跟踪;机电暂态数学模型与详细模型特性接近,能够从总体上反映永磁直驱风电系统对端电压变化的有功、无功响应,PSO参数辨识有效。研究结果表明,所建立的详细模型能够用于控制方式的研究以改善输出特性,机电暂态模型能够用于研究电网与永磁直驱风电系统的相互影响。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.