电力变压器安装及其保护调式

电能配送与传输离不开电力变压器,变压器的运行的安全可靠性不仅关系到用户的电能质量,更关系到整个电力系统的安全.一旦变压器发生问题或故障,那么将会损坏设备、甚至导致整个电力系统运行中断,所以电力变压器前期的安装调试工作极为重要.电力变压器的安装调试必须遵循施工顺序及操作方法,只有安装合格,才能保障变压器的正常运行.本文主要分析了电力变压器的具体安装技术及其保护调试,以期为相关工作予以指导.     

浅析电力变压器故障原因及处理方法

在电力系统当中,电力变压器是一个非常重要的组成部分,起着变换电压和保持电能的稳定的作用。但是,因为电力变压器的部结构非常复杂,所以在长期的运行当中,会出现一些故障,会直接的影响到整个电力系统。电力变压器能正常的运行,是对整个电力系统可靠,安全,经济,优质运行的保障。所以,必须减少和防止电力变压器的事故和故障的发生。本文将具体的分析一下电力变压器故障产生的原因及其处理方法。     

分析电力变压器铁芯接地故障的类型、原因及危害

电力变压器作为电力系统的关键设备,与整个电力系统的正常运行有着密切的关联。但是受多种因素影响,电力变压器在运行中会发生各种故障,其中电力变压器铁芯接地就是最为常见的故障类型之一。因此,本文就电力变压器铁芯接地故障的类型、原因及危害进行分析。     

继电保护技术在变压器故障中的改进措施

电力变压器是电网的重要组成部分同时也是电力结构的关键节点,变压器的正常稳定运行是在整个电力系统运行的关键,会直接影响电力系统的安全运营,在现代电力网络系统中通常采用继电保护技术对变压器实施相关保护工作,这也给变压器的继电保护工作提出了一定的要求,本文根据电力变压器继电保护工作中常见的问题,提出了优化电力变压器继电保护措施,提高变压器继电保护运行水平的措施和方法.     

变压器差动保护分析

一 概述 电力变压器是电力系统中十分重要的设备,如果出现故障将对供电可靠性和系统的正常运行带来严重的影响,特别是大型电力变压器,更是很贵重的设备.为了避免变压器事故的扩大,要求变压器内部发生故障时应迅速切断电源,使变压器退出运行.由于变压器的过流保护、速断保护还存在一定的死区,所以规定对于大容量变压器应装设电流差动保护. 变压器的纵联差动保护,是将变压器的一次侧和二次侧电流的数值和相位进行比较而构成保护装置,是变压器的主保护之一;变压器的差动保护主要用来保护变压器绕组南部及其引出线上的相间短路,同时也可以保护变压器单相匝间短路和接地短路.     

电力变压器在线监测与故障诊断研究

在我国电力系统中,电力变压器是非常核心的一项设备,只有其可靠、安全的运行才能够使整个电力系统的供电行为得到保证。而如果电力变压器在运行的过程中出现故障,那么就会直接对整个电力系统造成大的危害,同时也会对整个电力用户以及电力企业造成极大的经济损失。目前来说,电力变压器故障出现的情况同其负荷的容量、运行环境以及绝缘方面都具有一定的联系,而仅仅通过一定事前预防的维修方式,则不能够较为及时的发现故障。这种情况的存在,就使得我们必须能够对变压器进行在线监测,从而在变压器工作的过程中能及时的发现问题。     

基于110kV变压器内部过热故障处理措施分析

变压器是电力系统中应用最多的电气元件,也是系统中最重要的元件之一。变压器使用的健康状况直接关系到电力系统运行的安全性和可靠性,因此及时发现变压器故障对保证变压器安全运行至关重要。下面本研究就针对110KV变压器内部过热故障的产生原因进行分析,并总结了一些处理措施。     

大型电力变压器常见故障预防及处理分析

大型电力变压器是电力系统中重要的设备,其本身性能对电力系统的正常运行具有重要意义。随着我国用电形势的日益紧张,大型电力变压器的作用显得越来越重要。大型电力变压器在运行过程中如果出现故障会影响到电力系统的正常运行,严重情况下甚至会产生巨大损失。本文将重点分析大型电力变压器的几种常见的故障。     

电力变压器绝缘监测的光纤技术特点与应用

电力变压器是电力系统重要的设备之一,它的性能决定着电力系统稳定安全运行。电力变压器绝缘劣化是引起电力变压器出现故障的主要原因之一,加强电力变压器绝缘情况即时监测能进一步保障电力变压器安全运行。传统电力变压器绝缘性能监测因受环境影响、监测范围和精度限制等,而光纤技术的应用给电力变压器绝缘监测技术带来了突破。本文通过实例分析了光纤技术在电力变压器绝缘监测中的应用特点。     

变压器差动保护的应用研究

变压器作为电力系统的重要组成部分,其安全性、稳定性直接关系着电力系统的正常运行,其故障的产生甚至是造成电力事故的出现,因此,必须注重变压器差动保护的研究和探讨。文章结合实际工作经验,在简要阐述变压器差动保护保护原理的基础上,对变压器差动保护应用相关问题进行分析,可为相关工作者提供参考。     

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.     

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.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks