电感器、变压器、线圈、阻流圈、磁头、磁芯

0622728基于波形系数的变压器励磁涌流快速识别算法[刊,中]/索南加乐//电网技术．—2006,30(11)．—71-76 (L)通过分析励磁涌流波形与磁化曲线的关系,提出了一种基于波形系数的变压器励磁涌流快速识别算法。利用空载合闸和内部故障后符合正弦特征的采样数据预测出参考波形,并将1/2周波内的采样数据与预测数据进行比较,以此定义波形系数。通过波形系数的大小区分变压器励磁涌流状态和内部故障状态。仿真和动模实验表明,该算法能在一个周波内准确识别出空载合闸和各种内部故障状态。参23     

变压器参数的测定

在分析计算变压器的运行问题时,必须首先知道变压器的各个参数,从而判定变压器的运行性能。变压器的参数可通过空载试验和短路试验来测定,本文分别对空载试验和短路试验的实验方法和参数计算做了说明,对变压器的实践运行与维护具有指导意义。     

基于电压突变量的变压器励磁涌流识别的探究

差动保护是电力变压器的主保护,但变压器空载合闸时出现的励磁涌流易造成差动保护误动作,如果能准确鉴别励磁涌流和故障电流,就能提高保护动作的可靠性。本文在二次谐波制动原理的基础上,提出了一种基于电压突变量的励磁涌流辅助判据,并利用MATLAB软件对励磁涌流进行仿真。     

空载变压器音频特性研究

研究了配电网中常用的降压变压器（６ｋＶ／３８０Ｖ）在音频激励信号频率下原端的阻抗特性,结论是：在音频激励信号范围内,变压器副边开路时,空载阻抗为容性;副边短路时,空载阻抗为感性;当频率确定时,随着变压器容量的增加,变压器空载阻抗下降;同一容量的变压器,随着频率的下降,空载容抗增加;副边接补偿电容时,空载阻抗为感性。     

Matlab/Simulink在“电力系统暂态分析”中的应用

Matlab/Simulink在多种领域得到广泛应用,并逐渐被电力系统的研究者作为高效的仿真分析软件。本文对Matlab/Simulink在“电力系统暂态分析”中的应用进行研究：首先给出电力系统三相短路实例;再利用理论计算和软件仿真两种方法对该系统空载运行时变压器低压侧母线发生三相短路的暂态过程进行分析;并得到短路电流周期分量与冲击电流。结果表明,用该模型仿真得到的电流特性与理论计算一致,模型仿真与理论分析在电力系统暂态分析过程中起到了互相支撑的作用。     

引入电流故障分量的非接地短路故障选相方法

在某些故障合闸角下,基于行波的故障选相方法会将三相短路误判为两相短路。本文将电流故障分量引入,提出了改进措施。Matlab/simulink仿真试验验证了该方法具有一定的可行性。     

变压器并联运行的探讨

介绍了不同技术参数的变压器在空载和负载时的并联运行情况,分别列举了变压比、短路阻抗和联结组别不同时对并联运行的影响。     

铁磁谐振及其消除措施

电力网络中含有电容参数和电感参数的元件 ,如发电机、变压器、电压互感器、消弧线圈、并联补偿电抗器等许多铁芯电感元件 ,这些元件大部分为非线性元件 ,而且系统中还含有并联补偿电容器、线路对地电容、线路间电容等具有电容性质的元件。当含有铁磁的电感元件与电容性元件组合不当时 ,可能形成振荡回路 ;如果满足一定的条件 ,就可能激起持续时间较长的铁磁谐振过电压。开关及刀闸的非同期合闸 ,带有变压器、铁磁式电压互感器的空载母线投入 ,配电变压器高压线圈对地短路等都可能引起铁磁谐振。在发生铁磁谐振时 ,其过电压倍数可达 2 5倍 …     

电视机的重点电流测量

在电视机检修过程中,通过用万用表进行重点电流测量,并与各自相应的正常电流值进行比较,可以判断出晶体管、集成电路的工作状态,判断电源、行扫描工作是否正常,以及电容器、电路板的漏电或击穿情况。这是一种十分有效的测量法,以下就简要介绍几点: 一、电源变压器初级空载电流测量电源变压器初级空载电流的目的是检查变压器是否存在短路故障。电源变压器初级     

变压器励磁涌流的产生原因及限制措施

我司#1主变大修后进行空载冲击合闸试验时,第一次正常,第二次充电时,变压器钟罩底部法兰的紧固螺栓处出现了明显火花及放电声,变压器保护未动作。停电后检查发现,变压器钟罩和底盘连接螺栓处有电弧烧伤发黑的痕迹。为什么会出现放电现象?应该采取怎样的限制措施呢?     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.