分布式电源接入对配电网电压的影响分析

针对分布式电源(DG,Distributed Generation)接入对配电网电压所造成的影响,研究了DG接入配电网的数量、容量、位置分别改变时对系统电压影响的变化规律。通过对不同类型分布式电源的节点模型进行分析处理,采用改进牛顿法配电网潮流算法对其接入辐射状配电网的各种情况进行精确计算,结合IEEE34节点系统的仿真试验,全面总结了DG在配电网中的接入数量、容量、位置分别改变时系统电压的变化规律。     

分布式可再生能源接入对配电网电压分布的影响分析

分布式可再生能源在中低压配电网的广泛应用,对配电网产生一定的影响。线路由单一电源变为多电源,线路电压也发生了变化。通过对分布式可再生能源接入后的中低压配电网电压变化进行理论分析,结合仿真算例,对不同接入位置、不同接入数量、不同接入容量的分布式可再生能源接入的中压线路分布情况进行分析,得到分布式可再生能源接入位置、数量及容量对线路电压分布的影响方式。     

分布式电源对配电网电压的影响分析

随着现代化社会对能源需求的急剧提升,分布式能源得到了越来越广泛的应用。大量分布式电源的接入,对传统电网也产生了多方面的影响。为充分研究分布式电源接入配电网后对其电压产生的影响,利用MATLAB软件的SIMULINK功能模块,对分布式电源和典型负荷两个部分分别搭建了典型的配电网模型,并从分布式能源接入与否与接入位置两个方面分析了其对传统电网产生的影响。经MATLAB/SIMULINK仿真运行得到配电网模型中各节点的电压,并进行数据处理,找到分布式电源接入传统电网中对其影响较小的位置,即配电网系统的中部以及靠近配电网母线的位置。     

分布式电源的分类及对电力系统的影响

分布式发电系统对配电网有着多方面的影响,传统的放射状链式配电网接入分布式发电系统后,配电网继电保护及妥全自动装置的配置和整定变得非常复杂和困难。本文分析了分布式电源的接入对原有的配电网继电保护和妥全自动装置运行的影响,并研究了分布式电源的分类、不同容量分布式电源对系统电压的影响,以及系统发生短路故障时,分布式电源由于容量和控制方式的不同,其向系统注入的短路电流不同的情况。     

分布式光伏与充电桩谐波交互影响研究

在新型配电网背景下,针对分布式光伏与电动车充电桩的并网问题,对充电桩产生的谐波机理进行深入剖析,并建立相关数学模型,揭示了分布式光伏并网对充电桩谐波产生的交互影响。最后,利用PSCAD/EMTDC软件搭建了充电桩与分布式光伏的模型,并接入IEEE 14节点配电网模型中,在不同接入节点、充电桩数量和分布式光伏容量的条件下,系统地研究充电桩并网与光伏并网在谐波交互方面的影响规律,为谐波源并网准入政策的制定提供了参考。     

浅析分布式电源对配电网网损的影响

分布式电源接入电网后会对系统网络损耗产生重要影响。分布式电源对网损的影响与分布式电源的并网位置、并网容量以及运行方式等密切相关。本文通过对10节点和33节点配电系统仿真及对仿真结果进行分析比较,研究了分布式电源以不同的容量、接入位置和功率因数接入电网后对配电网网损的影响。得出了相应的结论,为降低网损提供了一定的理论依据。     

考虑时序特性的分布式电源对配电网的影响

针对分布式电源出力时序特性与负荷时序特性,研究了风力发电和光伏发电在不同的渗透率组合情况下对系统网损的影响及网损最小时的电压变化规律。运用前推回代法潮流计算程序对其接入辐射状配电网前后有功损耗和电压进行精确计算,并采用系统总网损、电压改善程度来评价分布式电源对系统网损和电压的影响程度。通过IEEE13节点系统的仿真试验,总结了风力发电和光伏发电在不同的渗透率组合情况下对配电网功率损耗的影响,并找出了使网损最小的风力发电与光伏发电最优安装容量的比例。     

浅析分布式电源接入对配电网的影响

简要叙述了分布式发电的类型和优点,介绍了配电网中接入分布式电源的影响,主要分析了分布式电源对配电网的设计规划以及配电网运行中的电压分布、电能质量、继电保护和其非孤岛运行的影响,指出了产生影响的主要原因和相关技术。     

分布式电源并网对配电网保护影响的研究

分析分布式电源接入对配电网传统继电保护产生的影响,针对这些影响提出了相应的保护措施和配置方案,为含分布式电源的配电网保护提供参考。     

基于组播通信技术的多源微网保护方案研究

新能源发电一般采用分布式发电方式,容量一般小于兆瓦级,安装在用户现场或者靠近用户现场处以满足特殊用户的需求,或者支持配电网的经济运行,或者两者并用。对用户而言,分布式发电提高了电能质量和供电的可靠性,带来很多便利。分布式发电接入配电系统之后,配电网从原来的单一受电结构变为了多电源结构,给电力系统的电压波动、谐波、继电保护等带来很大影响,因而目前的新能源发展方式必将改变配电网的运行方式。鉴于此,在分析微网系统保护现状的基础上,对采用组播通信方式实现微网保护的方案进行了介绍,并探讨了通信方式的引入在微网保护中的推广和影响。     

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.