光纤通信外文资料及翻译.doc

附件1：外文资料翻译译文光纤通信在配电网自动化上的应用 1前言 广泛分布的电话主导着通讯网络的第一个阶段并贯通了90多年。但是，电报领先于电话30多年，打字机领先于电话半个世纪。1844年，电报的发明者，塞缪尔-莫尔斯从华盛顿发送第一条电报给他在马里兰-巴尔的摩的同事韦尔。1876年，贝尔发明电话，之后不久，人们就意识到有线电话必须集中到一个中心点上，电话到电话的链接才能建立起来。这些点是手动开关板，有值班操作员控制。之后引进了机电开关，在1889年，第一个双端可动的步进交换机产生。第二次世界大战之后，整个长途网络自动化后，自动电话进入了黄金期。晶体管的发明推动了电子在交换系统中的运用，带来了20实际50年代后期第一代电子交换机的发展。电子交换机使设计和建成的交换机拥有更大的容量。通讯网络的第二个阶段发生在20世纪60年代，包含三个主要的里程碑：软件，数字交换，和卫星的发射部署。通信网络的第三个阶段发生在上世纪70年代，以数据网络和分组交换技术的引进为特征。为了实现电脑与分组交换网络的兼容性，1976年，国际电报电话咨询委员会建立了一个世界标准的协议，称为X.25。这个阶段的通讯网络以局域网的引进和推广为特征。1959年，光纤的产生在光通信领域带来了跨越式的技术发展。康宁光纤实验室发布第一个低能耗光纤，可以实现20Db/km 损耗。通讯网络的第四个阶段开始在上世纪80年代，以综合业务数字网和移动通信的运用为特征。随着国家经济的发展和人民生活水平的提高，人们对电力的需求日益增长，同时对供电的可靠性和供电质量提出了更高的要求。配网馈线自动化是配网系统提高供电可靠性最直接有效的技术手段之一。在近几年国家加大了对城网和农网的改造，国内各大供电局对配电网自动化的投入也在加大。在配网自动化实现的过程中，我们发现通信问题是一个难点问题。在此，仅就光纤通信在配网自动化方面的应用谈一点认识和体会。 2配电网自动化对通信的要求 同调度SCADA系统一样，配电自动化系统也需要一个有效的通信网，同时他有自己的特点：终端数量极多。配网系统拥有众多的开闭所、配电变压器、柱上断路器，要对这些设备进行监控就需要许多FTU和TTU，同时这些FTU随配电设备安装，地域分布广，通讯节点分散。 配网自动化系统的规模、复杂程度和自动化程度决定了通信系统应满足下述要求： (1)可靠性： 配网系统的通信设备有很多暴露在室外，环境恶劣，因此必须能够抵御高温、低温、日晒、雨淋、风雪、冰雹和雷电等自然环境的侵袭。同时，尽量避免各种电磁干扰，保证长期稳定可靠地工作，并要求在线路停电时，通信系统仍能正常工作。 (2)经济性： 考虑到配电网系统的总体经济效益，通信系统的投资不应过大，力争充分利用现有的主网通信资源，进行主、配网整体规划，避免重复投资。 (3)寻址量大： 通信系统不仅要考虑目前及未来的数据传输的需要，还要考虑系统升级的要求。 (4)双向通信： 配网自动化要实现遥测、遥信、遥控功能，就必须要求具有双向通信能力。 (5)容易操作和免维护。 根据以上的要求，伴随着光纤价格的下降，目前，光纤通信正广泛地应用于电力系统。 3光纤通信 自激光器和低损耗光纤问世以来，光纤通信系统以其技术、经济上无可比拟的优越性而迅速崛起，并风靡全球。该系统是以光纤为传输介质，以光为载波信号传递信息的通信系统，应用的光波波长为1.01.m靘，整个系统由电端机、光端机、光缆和中继器构成。光纤可分为单模光纤(SMF)、多模光纤(MMF)、长波长低射散光纤(LMF)、保偏光纤(PMF)及塑料光纤(POF)等很多种；常用的为单模和多模光纤，多模光纤就是传输多个光波模式，而单模光纤只传输一个光波模式。单模光纤比多模光纤传输距离长，目前一般地，光信号在多模光纤内可传6km左右，在单模光纤内可传30km。因此，单模光设备的价格要高于多模光设备。实用的光纤通常都是由多根光纤、加强芯、保护材料、固定材料等组合成光缆构成的传输线。 光纤MODEM可完成光信号与数字信号之间的相互转换。光纤MODEM一般有一个以上的数据口用以传递同步或异步信号。通信速率可达到2Mbps或更高，配网常用的通信速率一般为同步N64K或异步19200bps以下。故足以满足配网通信的需要。另外，还有一种光纤MODEM具有双环自愈功能。这一功能使通信的可靠性大大增强。使通信不受影响，同时向主站发出相应的告警及定位信号，使维修人员及时修复故障段光缆。 4光纤通信的特点 光纤通信具有通信容量大，衰减小，不怕雷击，抗电磁干扰、抗腐蚀、保密性好、可靠性高、敷设方便等优点，不过投资费用相对较高，尤其对于城区内直埋式电缆线路的光纤敷设，施工费用将更大。 5光纤通信在配电网上的实现方案 光纤通信的组网方式非常灵活，可以构架成星型、链型、树状、网状、单纤网、双纤网、环上多分支、多环相交、多环相切等各种拓扑结构的网络。 根据配电自动化系统的特点，光纤网通常需组成环型网，并与计算机局域网连接，实现数据共享。 实际工程设计中，充分考虑到电力通信专网拓扑结构的复杂性，SDH传输系统可以采用多达126个E1(2M口)全交叉连接和双主光环+多光分支的设计思想。基本构架为13个SDHSTM-1双纤自愈环相交或相切，而且在需要时，可通过更换光卡的方式在线升级为SDHSTM-4。如果局调度中心局域网位于网络地理中心，建议设计为相切环，以调度中心为切点；如果局调度中心局域网偏离网络地理中心，建议设计为相交环，由于调度中心不在交点，为了环间可靠转接，各环相交至少两点，互为保护路由。6结束语 在实际的配网自动化的通信系统，必须构建一个成本低、收效高的双向通信系统，用可以接受的费用在可靠性和信息流量方面提供非常高的性能。同时，由于配电网自动化系统所要完成的功能太多而系统复杂，采用单一的通信系统来满足所有的功能需要是不现实的，也是不经济的。因此，在配电网自动化系统中，要应用多种通信方式，按综合的经济技术指标而选取其中最优的组合。在电力系统中较常用的通信方式还有一点多址数字微波、数传电台、无线扩频、专线电缆、邮电本地网、载波、扩频载波等，可供组网时选择。 Optical fiber communication in power distribution automation applications on paper 1 Foreword The first phase in the evolution of communication networks is dominated by the wide spread of telephony and covers over 90 years . However ,the telegraph preceded the telephone by more than 30 years and the teletypewriter by half a century . In1844, Samuel Morse , the telegraphs inventor ,sent the first telegraph message from Washington D.C. to his coleague Afred Vail in Baltimore, Maryland. Shortly after the invention of the telephone by Alexander Grahan Bell in 1876 ,it was realized that telephone wires had to converge on central points where telephone-to-telephone connections could be made .These points were manual switch-board,Staffed by operator .This was followed by the introduction of electromechanical switching and in 1889,Almond B.Strowger invented the first two-motion step-b-step switch. The golden age of automatic telephony occurred after Word War when the entire long-distance network was automated . The invention of the transistor spurred the application ofElectronics to switching systems and led to the deployment of the first electronic switching in the late 1950s . Electronic switching made it possible to design and build switches with greater capacity. The second phase of networking ,which occurred in the 1960s ,included three major milestones:software switching ,digital transmission ,and satellite deployment. The third phase of the evolution of communication networks occurred in the 1970s and is characterized by the introduction of data networks and packer switching technology. To achieve compatibility between computers and packet-switched network ,the international Telegraph and Telephone Consultative Committee (CCITT from the French acronym established a word-standard protocol, called X.25 in 1976. This phase of networking is also characterized by the introduction and wide acceptance of local area networks(LANs). The invention of the laser (which stands for light amplification by simulated emission of radiation ) in 1959 led to major technical developments in the field of optical communication. 1970, Corning Glass Works reported on the first low-loss optical fiber (dopedsilica clad fiber ) that achieved 20 dB/km loss. The fourth phase of communication networking ,which began in 1980, is characterized by the availability of the integrated services digital networks (ISDN) and mobile communications.With the development of national economy and peoples living standards improve, peoples growing demand for electricity, while the reliability and power quality of power supply put forward higher requirements. Feeder Automation is the reliability of power supply distribution network systems to improve the most direct and effective means of technology. Countries has increased in recent years on the city network and the transformation of rural power network, power supply bureaus of the major domestic investment in distribution automation is also increasing. Achieved in the distribution network automation process, we found that communication problems is a difficult problem. In this, just from the fiber-optic communication networks in automation applications with little knowledge about and experience. 2 Distribution Automation requirements for communication SCADA system with the same dispatch, distribution automation system also needs an effective communication network, and he has his own characteristics: the number of terminals very much. System has a large distribution network by opening and closing, power distribution transformers, circuit breakers column to monitor these devices requires a number of FTU and TTU, while the FTU with the power distribution equipment installation, wide geographical distribution, communication nodes scattered. Distribution automation system size, complexity and automation level of the decision of the communication system should meet the following requirements: (1) Reliability: Communications equipment distribution network systems have many exposed outdoors, bad environment, so must be able to withstand heat, cold, sun, rain, snow, hail and lightning and other natural attacks. Meanwhile, try to avoid all kinds of electromagnetic interference, to ensure long-term stable and reliable work, and asked when the line power failure, communication system can still work properly. (2) economy: Taking into account the overall economic power distribution system, communication system, investment should not be too large, and strive to make full use of the existing main network communication resources, for the Lord, the overall distribution network planning, avoid duplication of investment. (3) addressing large: Communication system not only to consider the present and future data needs, but also consider the upgrade requirements. (4) two-way communication: Distribution network automation to achieve the telemetry, remote, remote control, you must request a two-way communication capabilities. (5) easy operation and maintenance. According to the above requirements, along with fiber prices down, at present, optical fiber communication systems are widely used in electric power. 3 Optical Fiber Communication Since the inception of laser and low loss optical fiber, optical fiber communication system with its technical and economic advantages of the rapid rise of unparalleled, and swept the globe. The system is based on optical fiber as the transmission medium to light as the carrier signal to transmit information in communication systems, applications of light wavelength of 1.0 1.m Jing, the entire system from the electrical side machine, Optical, cable and repeaters pose. Fiber can be divided into single-mode fiber (SMF), multi-mode fiber (MMF), long-wavelength low drive bulk fiber (LMF), polarization maintaining fiber (PMF) and plastic optical fiber (POF) and so are many; commonly used for single-mode and multi-mode fiber, multimode fiber is more than light transmission mode, and single-mode fiber transmission of a light wave mode only. Single-mode fiber multimode fiber transmission distance than the length, the current general, the optical signal in the multi-mode optical fiber to be available for about 6km, the single-mode fiber transmission within 30km. Therefore, the price of single-mode optical devices than multi-mode optical devices. Practical optical fibers are usually more to strengthen the core, protecting materials, fixed materials combined to form the transmission line cable. Fiber MODEM to be completed by optical signal and digital signal conversion between. Fiber MODEM generally have more than one data port to transfer synchronous or asynchronous signals. Communication speed up to 2Mbps or higher, with commonly used network communication rate is generally synchronous asynchronous 19200bps N 64K or less. It is sufficient to meet the needs of distribution network communication。 In addition, there is a double-loop fiber optic MODEM with self-healing func-tion. This feature greatly enhance the reliability of the communication. the signal is not affected, while the main station to send the appropriate alarm and positioning signals, so that maintenance personnel section of cable fault repair time. 4, the characteristics of optical fiber communication Large capacity optical fiber communication with the communication, the attenuation is small, not afraid of lightning, anti-electromagnetic interference, corrosion resistance, confidentiality, reliability, and easy installation, but the relatively high investment costs, especially for inner city buried cable lines fiber laying, construction costs will be greater. 5, optical fiber communication implementations in distribution networks Optical fiber communications network formation is very flexible and can frame into a star, chain, tree, mesh, single fiber network, dual-fiber network, ring multi-branch, multi-ring intersection, tangent, and other multi-ring topology network. According to the characteristics of distribution automation systems, fiber optic ring net usually made up of network and computer local area network connection, data sharing. She Ji practical engineering, the fully take into account the special network topology power structure of communication complexity, SDH transmission systems can use up to 126 E1 (2M I) Quan cross Lian Jie He pairs the main branch of halo + more than the design of Si Xiang Guang. The basic framework of 1 to 3 SDH/STM-1 dual-fiber self-healing intersect or tangent, and when necessary, can change the way light card online upgrade SDH/STM-4. If the Bureau of the network control center is located in the geographical center of the LAN, the proposed design for the tangent to the