用户多电源供电储能系统蓄电池充放电控制研究

为了提升蓄电池充放电控制的准确性,对用户多电源供电储能系统蓄电池充放电控制进行研究。通过设计双向AC/DC变换器实现蓄电池充放电控制,以双向AC/DC变换器一般数学模型为基础,加入同步旋转坐标系构建双向AC/DC变换器dq模型,提升蓄电池充放电控制的准确性;并网运行时,双向AC/DC变换器利用PQ控制策略,完成蓄电池充放电过程中功率平衡控制;离网运行时,双向AC/DC变换器利用V/f控制策略,完成蓄电池充放电过程中电压与频率的平衡控制。实验结果表明,所研究蓄电池充放电控制策略能够有效控制蓄电池充放电,提升蓄电池充放电过程中功率平衡控制的准确性。     

含多微源的混合微电网控制策略与仿真

针对微电网内部分布式电源和负荷的多样性、分散性,在分析P/Q控制以及基于下垂特性的V/f控制策略的基础上,采用了一种P/Q-V/f对等控制策略。该策略可有效实现负荷功率共享,保证微电网频率和电压的稳定。在PSCAD/EMTDC仿真平台上对所建微电网模型进行运行模式转换以及孤岛下切/增负荷的仿真分析,证明所提出的控制策略的有效性与正确性。     

电力电子在微电网中的应用研究

目前,越来越多的分布式电源接入了配电网当中,改变了传统配电网的结构,并且分布式电源的并网运行可能会引起电网的电压偏差、频率偏移等问题。微电网概念的提出就是为了削弱分布式电源对配电网的影响,最大化接纳分布式电源。在微电网中,电力电子技术扮演着重要角色,而变流器的控制是其中的一个核心。变流器的控制是实现微电网控制的具体方式,而微电网的运行控制是微电网稳定运行的前提。因此本文以逆变器为例,对变流器控制在微电网运行控制当中的应用进行了概述,并且归纳了变流器的关键新兴技术在微电网中的应用。     

一种主从控制模式下微网主电源逆变器的控制策略

微网作为可再生能源与电网之间的缓冲和纽带,有助于提升电力系统柔性和电力系统可靠性。给出了微电网主从控制系统的结构,主电源和从电源通过三相逆变器接入微电网交流母线,分析了逆变器及其控制系统。当微电网处于联网运行时,并网逆变器采用恒功率控制模式,当微电网系统独立运行时,主电源采用恒压频比控制模式,给出了具体的控制结构和模式切换控制策略。该控制策略可以有效抑制切换过程中微网母线电压和主电源输出电流波形畸变,有效避免切换过程所造成的微电网母线电压突降,减小切换过程对微电网冲击。     

基于风光储双层母线微电网的分布式模型预测控制

针对风光储互补的双层母线直流微电网系统,提出一种基于多端口变换器直流微电网分布式模型预测控制策略。首先,建立各个子微网系统中风电系统、光伏系统和储能系统的数学模型,其次,依据风电系统、光伏系统工作在经济最优,发电功率最大,储能系统作为补充的原则,采用分布式模型预测控制算法优化风电系统、光伏系统输出功率,保证高低压侧母线负荷跟踪性能和经济性能。最后,通过微网间DC/DC变换器进行PI控制,实现高低压母线间能量平衡,维持母线电压稳定。通过仿真、实验验证,所提控制策略能够实现各个微电网发电单元经济最优的同时,维持高低压侧母线的功率平衡和母线电压稳定,提高了系统的运行可靠性。     

两级式双向变流器控制策略研究

对一种含双向DC-DC变流器和双向DC-AC变流器的两级式功率变换系统(Power Conversion System)PCS的拓扑结构和工作原理进行了详细介绍,提出了一种基于统一控制的阶段式充放电控制策略。建立了Simulink模型并对模型进行了仿真和分析。仿真结果表明:提出的控制策略可以简化控制器设计和运行,为电池组提供安全、灵活的充放电模式选择,同时还具有良好的暂态和动态性能。     

三相变流器线性二次型电流控制研究

三相变流器可实现DC／AC、AC枕能量变换。在三相变流器中,研究变流器的电流控制,可以实现消除谐波,实现ACDC的单位功率因数,DC／AC并网功能以及实现DC／AC双环控制。三相变流器其数学模型为耦合多变量系统,可以选择状态空间的设计方法。笔者提出了一种线性二次型的分析控制方法实现变流器电流控制。调节器结构简单,易于工程实现。     

基于复合式发电系统的双向DC/DC变换器研究

太阳能、风能、潮汐能等分布式能源研究与应用日益广泛,采取了一种含储能系统的分布式发电系统模型,利用超级电容构成的储能系统减少分布式能源由于间歇性、不持续性、易波动性给电网带来的冲击。超级电容经双向DC/DC变换器向直流母线供电,针对传统变换器电流纹波较大、开关器件电压应力高的问题,研究了一种新型双向DC/DC变换器,分析了其工作原理,结合一种移相控制策略,能增强系统运行稳定性,减少了能量损耗,提高系统转换效率。     

基于飞轮储能和蓄电池的微电网控制策略

微电网作为一特殊的电网运行方式,可运行在并网和孤岛两种模式下。对微电网中的电源及整个微网进行有效控制是微电网技术中的关键。为保证微电网的稳定可靠运行,并在运行模式改变时,完成有效、平滑的切换,在构建不同类型的分布式电源的基础上,提出了以蓄电池为主电源,用飞轮保证不间断供电的微电网系统协调控制方法。该控制方法保证了微电网经济、稳定运行和良好的供电质量,并且能够在微网运行模式切换过程中维持其内部不间断供电并大幅减少暂态冲击,迅速过渡到稳态运行。建模仿真结果证明了该控制策略的有效性和精确性。     

电源变换技术的发展

一、概述 电源变换,广义地讲,就是将某一频率、某一电压的电源通过电子线路或其他手段得到所需的频率和电压的电源所进行的变换。它包括:DC—DC变换,将一种直流电压变换为另一种直流电压;AC—DC变换,将交流电压变为直流电压;DC—AC变换,将直流电压变为所需的交流电压;AC—AC变换,将一种频率的交流电压变为另一种频率的交流电压。目前,电源变换大多采用电力电子技术。     

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.