建筑电气毕业设计外文翻译及译文

本科毕业设计（论文）外文资料翻译系别：电气工程系专业：建筑电气与智能化班级：姓名：学号： 2007318230外文出处：《Electricity》附件：1、外文原文；2、外文资料翻译译文。

weak electricity engineeringSystem functionThe in common use building weak electricity system mainly has a few kinds as follows: (1)The telephone corresponds by letter systemCarry out telephone(include three types of facsimile machines, can see a telephone...etc.) correspondence function The star type To rushes toward structure; Use 3 types(or above) don't shield a double to wring line, deliver the frequency of signal within the scope of audio frequency.(2)Area net system in calculator bureauIs a realization to transact to automate and various data delivers of network foundation The star type to rushes toward structure Use 5 types(or above) don't shield a double to wring line, deliver number signal, the baud rate can reach to a 100 mbs the s is above.(3)Music| broadcast systemThe loudspeaker passed to install on the spot(is like places, such as market, restaurant, guest room and hallway...etc.) broadcasts music, and can pass to transmit sound machine to carry on a broadcasting to the spot Many road total line structure Deliver is certainly pressed a 120 Vs by the power enlarger output's| the audio frequency signal of 120 Ωs with drive the spot loudspeaker phonation, deliver the line use copper Xin to insulate to lead line.(4)The cabled T.V. signal assigns systemEvenly assign the cabled T.V. signal to each customer inside the building to order ;Adopt branch and assign a machine to carry on a signal allotment, for letting up signal to lose to really reduce and make each customer order the request that the signal quality attains norm rules with , its cloth line is tree type structure, and order to distribute with the form of building and the customer of dissimilarity but dissimilarity Use 75 Ω radio frequency coaxial cable, deliver many road radio frequencies signal.(5)The public security supervises and controls systemThe camera passed to install on the spot, guard against theft equipment like carry on surveillance and excrescent circumstance to report to the police to each exit and entrance and some important places of building etc. ;The video frequency signal delivers to adopt star type structure, use video frequency coaxial cable ;Control delivering of signal to adopt total line structure, the use copper insulates a cable.(6)The fire fight reports to the police systemThe system is reported to the police by a fire and the fire fight is allied the broadcasting system, fire alarm moving system, fire fight to constitute towards speaking 3 parts like telephone system.A fire reports to the police and the fire fight is allied and move system to pass constitution in the building everywhere of a fire locator, hand move to report to the police device etc. to the spot the circumstance carry on a monitor, be have already reported to the police signal, according to receiving of signal, according to in advance setting of procedure, unite the homologous equipments spreads by control fire, its signal delivers to adopt total line structure of many roads, but for important fire fight equipments(if fire fight pump, spray to sprinkle a pump, is pressing breeze machine and line up smoke breeze machine etc.) of allied move to control delivering of signal, sometimes adopt star type structure, the delivering of signal uses copper to insulate a cable.(the product having asks use double to wring line)The fire fight broadcasting system is used for to direct the spot while taking place a fire a personnel safety evacuation, adopt total line structure of many roads, the signal delivers to use copper to insulate to lead line.(the system can and music broadcasting system suitable for use) The fire alarm is two kinds of structure towards speaking that the telephone system is used for in command of spot fire fighter to carry on extinguishing fire a work, adopt star type and total line type, the signal delivers uses to shield line.(7)The exit and entrance controls systemUse calculator, intelligence Carmen equipment, such as lock and card reader...etc., carry on constitution, surveillance, control and record etc. to each exit and entrance status, carry out unify a management to each exit and entrance of building, promise mansion safety, its Tuo rushes toward structure and delivers to lie quality because of product but difference.(8)The parking lot charge manages systemPass to install under the exit and entrance ground of respond coil, respond the discrepancy of vehicle, pass artificial half auto the full-automatic charge management system, carry out a charge and control the Qi of dynamoelectric railing to shut... The system cloth's line is only limited by the exit and entrance of car field in the mansion, each exit and entrance from one set controller control, the controller can independently work as well as manage a calculator allied net with place of honor, its cloth line structure and deliver to lie quality because of product but difference.(9)Building Yu from control systemThe various examination and performance spare part passed to connect with each other with the spot controller, to mansion inside outside of the work status of various equipments(is like air condition, to the catchment, lighting, is provided to go together with equipment, such as electricity and elevator...etc.) inside various environment parameter and building carry on examination, surveillance and control, and link through a calculator network each the spot controller, carry on reasonable allotment and management to the resources and the equipments in the building, attain a comfortable, convenient, economical and dependable purpose .So far, building Yu from control system didn't yet international standard, the correspondence adopted by the product of different factory house negotiates each not same, it the spot total line and control the of total line to rush toward structure and deliver to lie quality also dissimilarity The underneath will make simple introduction towards being wide spread accepted by the international society currently and Works technique and technique for adopting.Also have the television meeting the system, expand a system and cruise more in addition system and building Yu to speak system, three forms(water, electricity, annoy form) automatically and copy form system The weak electricity system that the building of different function needs to be established is each not same.3 systems are integratedIn the middle of physically working, the design should integrate 3 aspects: etc. to consider an integrated problem between the systems of each weak electricity from the network integration, function integration and software interface.3.1 networks are integratedThe network integrates mainly on-line come to consider from the cloth of each system, make the weak electricity system of different function able to work the platform is at an unified cloth line up, so, on the other hand easy to also make on the other hand each weak electricity system to the management of clothes line systems on the spot the decoration of equipments up have larger vivid.At in common use building weak electricity system in, the telephone corresponds by letter system and the function of area net in the calculator bureau system and the hardware equipments of the use each not same, but it the network rush toward the decoration principle that the structure, information orders homology, and can use homology of delivering and lying quality and connect a plug-in, so can synthesize two cloth lines of systems as a cloth linesystem Thus, two systems can be an exploitation, the information orders of the function can change with each other and make two systems all have larger vivid, this is also we say of synthesize cloth line system(PDS).Remaining as to it's is a few systems, in the comprehensive consideration technique and economic possibility, current product because of being rushed toward by system Tuo the structure, signal deliver to lie quality and double wring line to synthesize PDS towards delivering power signal of limiting etc., its cloth line system temporarily canning not returning But, along with the continuously developing of the number signal processing theory and application technique and calculator technique, and correspondence technique...etc., future PDS will definitely develop to become the cloth line that includes more different function weak electricity systems platform.3.2 functions are integratedThe function integration includes a following both side contents:(1) the function merge Main consideration will some on the function and hardware equipments up repeated of the system merge and make to merge the system of the empress before having merger all functions of each system, with decrease equipments redundancy, avoid repeated investment In the above-mentioned system, music broadcasting system and fire fight report to the police and allied move the fire fight within system broadcasting system and then can be a system to design, but the system has to satisfy the rules of 《the fire fight automatically reports to the police a system design norm (GBJ 50116-98)》.(2) the function repair with each other See from the function, each sub- systems in the building Yu automation all have its particular function and rule over scope and respectively and independently work at ordinary times, but while taking place some and special affairs, usually needing an of each system can be in conjunction with a work, the whole system carries out overall control and management the exaltation to the processing ability that bursts affairs, exaltation building of the intelligence turn degree Is concrete of allied move to respond to include a few systems as follows:The fire fight reports to the police system →music broadcasting system When occurrence fire fight reported to the police, correspond the public broadcasting system of floor will drive strong line of cut over into an urgent broadcasting of fire fight;The fire fight reports to the police system →the public security supervise and control system When occurrence fire fight reported to the police, the public security supervised and control system to automatically be like the shooting of camera of fire alarm close by district theappearance sliced to hold to lord surveillance in the public security center and laid equal stress on some to record these shooting of cameras to be like contents with provide whether the confirmation has fire alarm occurrence to analyze with the after the event trouble reason etc.; The fire fight reports to the police system →the exit and entrance control system While confirming to take place fire fight to report to the police exit and entrance's control the each control door(the control door of important core part can establish alone) having something to do with fire alarm part in the system should automatically be placed in to open status, for the purpose of internal personnel evacuate to withdraw to get into with fire fighter;The fire fight reports to the police system →the gara ge manage system The garage management system should control garage while confirming fire fight to report to the police occurrence at the first floor or the underground layer the gateway place in open status, so that the vehicle inside the garage quickly withdraw a fire field;(at this time garage relevant of the camera should be placed in a work and record image status)The fire fight reports to the police system →the speech correspond by letter system After the fire fight reports to the police the system auto confirmation fire fight to report to the police occurrence, immediately pass the speech in the mansion correspondence system reports to the police to the fire fight bureau and deliver concerning the information, report to the police to supervisor's section in the mansion at the same time;Building Yu from control system →the public security supervise and control system When building Yu from control system to have difference to report to the police or trouble, the public security supervision system can automatically will report to the police the shooting of camera of close by district to be like appearance to slice to hold to lord surveillance in the public security center and lay equal stress on some to record these shooting of cameras to be like contents to provide after the event analysis the reason etc.;The public security supervises and controls system →building Yu from control system When the public security system reports to the police, can unite elevator control system, the elevator doesn't stop to depend to report to the police a layer, or stop to depend a public security member appointed layer;The exit and entrance controls system →the public security supervise and control system When control door at not work when someone hold card into or take place illegal incursion the public security supervises and controls a system auto will get into of control door or report to the police a shooting of the camera of ordering the close by district to be like appearance toslice toward the public security center lord surveillance hold, lay equal stress on some to record these shooting of cameras to be like contents to check when it's necessary by providing; The garage manages system →the public security supervise and control system When the garage has vehicle discrepancy, the public security supervises and controls a system auto to be like the shooting of camera of garage door appearance to slice to hold to lord surveillance in the public security center and lay equal stress on some to record these shooting of cameras to be like contents to check when it's necessary by providing.In fact, the function between each system is integrated and allied to move to respond to have no one mode of unified or fix, can establish according to the effective demand.The function integrates a purpose just, in fact existing two kinds of modes, 1 kind is at each statures system on build up higher and first-degree management and control network, another is with building Yu from control system for center of integrated mode No matter choose which integrated mode, key techniques' all wanting to work out a correspondence problem between each system , while making sure a solution, must adopt theory forerunner and technique maturity and wide spread accept for industry and the correspondence adopting negotiate.The building Yu been widespread accepted by the international society currently from control correspondence agreement of realm, is provided heat by the United States and make cold regulate the association establishment of engineer with air, and become standard ANSI of of ASCII|ASHRAE Standard 135-1995), it matches ISO(international standardizing organization) OSI(open system with each other connect)7 F model, forgiving 5 kinds already mature network correspondence agreement, including correspondences such as ether net and Long Talk etc. agreement Among them, the ether net correspondence agreement is an OA system to widespread use of a kind of correspondence agreement, majority of network operate systems all support this correspondence agreement But the Works technique is the new generation that the United States' Echelon company develops the spot total line technique, its outstanding advantage is to support arbitrarily to rush toward structure and support variety's delivering to lie quality(include a double to wring line, electric power line, wireless electric wave, infrared ray, coaxial cable and fiber optic), and variety lie quality can mix to use in the same network, as a result consumedly simplified engineering construction and system to be finished after of change to set up, extension and maintenance work Therefore, building Yu according to standard from control system, can a little bit easily carry out at the its control total line class and the integration of OA system, again because it forgives of the correspondence negotiatesupport double to wring line and star type to rush toward structure, as a result can use PDS as its signal to deliver path.弱电工程弱电系统功能常用的建筑弱电系统主要有以下几种：(1) 电话通信系统实现电话(包括三类传真机、可视电话等)通信功能；星型拓扑结构；使用三类(或以上)非屏蔽双绞线，传输信号的频率在音频范围内。

1 工程概论1.1 工程专业1.2 工业和技术1.3 现代制造业工程专业1 工程行业是历史上最古老的行业之一。

如果没有在广阔工程领域中应用的那些技术，我们现在的文明绝不会前进。

第一位把岩石凿削成箭和矛的工具匠是现代机械工程师的鼻祖。

那些发现地球上的金属并找到冶炼和使用金属的方法的工匠们是采矿和冶金工程师的先祖。

那些发明了灌溉系统并建造了远古世纪非凡的建筑物的技师是他们那个时代的土木工程师。

2 工程一般被定义为理论科学的实际应用，例如物理和数学。

许多早期的工程设计分支不是基于科学而是经验信息，这些经验信息取决于观察和经历，而不是理论知识。

这是一个倾斜面实际应用的例子，虽然这个概念没有被确切的理解，但是它可以被量化或者数字化的表达出来。

3 从16、17世纪当代初期，量化就已经成为科学知识大爆炸的首要原因之一。

另外一个重要因素是实验法验证理论的发展。

量化包含了把来源于实验的数据和信息转变成确切的数学术语。

这更加强调了数学是现代工程学的语言。

4 从19世纪开始，它的结果的实际而科学的应用已经逐步上升。

机械工程师现在有精确的能力去计算来源于许多不同机构之间错综复杂的相互作用的机械优势。

他拥有能一起工作的既新型又强硬的材料和巨大的新能源。

工业革命开始于使用水和蒸汽一起工作。

从此使用电、汽油和其他能源作动力的机器变得如此广泛以至于它们承担了世界上很大比例的工作。

5 科学知识迅速膨胀的结果之一就是科学和工程专业的数量的增加。

到19世纪末不仅机械、土木、矿业、冶金工程被建立而且更新的化学和电气工程专业出现了。

这种膨胀现象一直持续到现在。

我们现在拥有了核能、石油、航天航空空间以及电气工程等。

每种工程领域之内都有细分。

6 例如，土木工程自身领域之内有如下细分：涉及永久性结构的建筑工程、涉及水或其他液体流动与控制系统的水利工程、涉及供水、净化、排水系统的研究的环境工程。

机械工程主要的细分是工业工程，它涉及的是错综复杂的机械系统，这些系统是工业上的，而非单独的机器。

Circuit breaker断路器Compressed air circuit breaker is a mechanical switch equipment, can be i 空气压缩断路器是一种机械开关设备，能够在n normal and special conditions breaking current (such as short circuit cur 正常和特殊情况下开断电流（比如说短路电流）。

rent). For example, air circuit breaker, oil circuit breaker, interference circ 例如空气断路器、油断路器，干扰电路的导体uit conductor for the application of the safety and reliability of the circuit 干扰电路的导体因该安全可靠的应用于其中，breaker, current in arc from is usually divided into the following grades: a 电流断路器按灭弧远离通常被分为如下等级：ir switch circuit breaker, oil circuit breaker, less oil circuit breaker, compr 空气开关断路器、油断路器、少油断路器、压缩空essed air circuit breaker, a degaussing of isolating switch, six sulfur hexaf 气断路器、具有消磁性质的隔离开关、六氟luoride circuit breaker and vacuum breaker. Their parameters of voltage, 化硫断路器和真空断路器。

他们的参数有电压等级、current, insulation level of breaking capacity, instantaneous voltage off ti 开断容量的电流、绝缘等级开断时间的瞬时电压恢复和me of recovery and a bombing. Breaker plate usually include: 1 the maxi 轰炸时间。

山东建筑大学本科毕业设计说明书外文文献及翻译格式模版1附件3：（本科毕业论文）文献、资料题目：院（部）专班姓名：张三学号：指导教师：张九光翻译日期：2005.6.30，the National Institute of Standards and Technology (NIST) has been working to develop a new encryption standard to keep government information secure ．The organization is in the final stages of an open process of selecting one or more algorithms ，or data-scrambling formulas ，for the new Advanced Encryption Standard (AES) and plans to make adecision by late summer or early fall ．The standard is slated to go into effect next year ．AES is intended to be a stronger ，more efficient successor to Triple Data Encryption Standard (3DES)，which replaced the aging DES ，which was cracked in less than three days in July 1998．“Until we have the AES ，3DES will still offer protection for years to come ．So there is no need to immediately switch over ，”says Edward Roback ，acting chief of the computer security division at NIST and chairman of the AES selection committee ．“What AES will offer is a more efficient algorithm ．It will be a federal standard ，but it will be widely implemented in the IT community ．”According to Roback ，efficiency of the proposed algorithms is measured by how fast they can encrypt and decrypt information ，how fast they can present an encryption key and how much information they can encrypt ．The AES review committee is also looking at how much space the algorithm takes up on a chip and how much memory it requires ．Roback says the selection of a more efficient AES will also result in cost savings and better use of resources ．“DES w as designed for hardware implementations ，and we are now living in a world of much more efficient software ，and we have learned an awful lot about the design of algorithms ，”says Roback ．“When you start multiplying this with the billions of implementations done daily ，the saving on overhead on the networks will be enormous ．”……山东建筑大学毕业设计（或毕业论文，二选一）外文文献及译文- 1 -以确保政府的信息安全。

（2016届）毕业设计文献翻译题目：姓名：学院：专业：建筑学班级：学号：指导教师：导师学科：导师职称：教务处制年月日嘉兴学院外文文献翻译译文1外文题目： Analysis of and Study on the Difficulties in the Fire Protection Design of Large Commercial Complex专业班级：学生姓名：学号：一、外文原文AbstractFire properties of the large commercial complex has been summarized. Based on the fact that there are contradictions between what is required for the large commercial complex in the fire code and the real application in practice, difficulties in fire protection of designing large commercial complex have been analyzed.Key words:large commercial complex; fire protection design; difficulty; research status1. IntroductionIn recent years, more and more large commercial complexes have appeared in China. These complexes integrate different businesses into on large building, where customers can do shopping, eat or enjoy themselves. According to the statistics, nearly 200 large complexes in China now have indoor walking street, with different kinds of shops standing along both sides. And what’s more, the indoor walking street shares the large space with the atrium.Generally speaking, the large commercial complex is multi-functional with high fire load and large assembly of people. The mechanism of the occurrence of fire is different from that of the ordinary buildings and the fire loss is also heavier. As a result, this kind of commercial complex needs higher fire safety. However, the current national fire code only gives the minimum requirements. No specific fire safety objectives are provided.Therefore, it is quite important to understand the design and research status of the large commercial complex and to provide safe, reasonable and economical fire design method.2.Characteristics of large commercial complex fire2.1 High fire occurrenceThere are heavy fire loads inside the large commercial complex, which include merchandises like clothes, shoes, hats and combustible decorations. It is widely recognized that electricity is the important factor to cause fire hazard. Therefore, to provide electricity among these combustibles is very dangerous. However, in the large commercial complex, electric systems and equipment are installed to provide electricity for lighting, ventilating and air conditioning. If there is short circuit, spark, poor contact or long time electrifying of the lights or electric heater, fire may be caused. In addition, other factors like improper welding, lighted cigarette ends or arson can cause fire too.2.2 Quick spread of fire and smokeIf fire occurs in a large commercial complex, it can spread very quickly and grow into a large fire in a short time, while the shelter of the rack usually decrease the sensitivity of the fire detection system and cause delay. As a result, fire can’t be detected and controlled timely. The other reason for quick fire spreading is that the vertical space formed by the atrium and escalators in the complex may help fire and smoke to spread to the whole building.2.3 Large casualties and property lossThe large commercial complex usually accommodates valuable merchandises and facilities. Once there is a fire, big property loss is inevitable. And what’s more fatal is that there are usually large assemblies present. The heavy smoke with CO, CO2, NOx, HCN not only affects the safeand quick evacuation of the people, but also put them in danger. According to the statistics of Japan and UK, the percentage of deaths caused by suffocation in the fire can be as high as 78.9%. As a result of a complicated layout, large assembly of people, long time to evacuate, the large commercial complex is susceptible to fatal fire accidents which usually suffer heavy casualties. For example, on Sept. 30, 1997, a fire occurred in a supermarket on the third floor of a shopping mall in Changchun, Jilin province. It caused 11 deaths and 2 injuries. The burning area reached 4500m2 and most of the commodities inside the supermarket were burnt. The direct property loss was RMB 14,611,000 Yuan.3.Analysis of difficulties in fire protection design of large commercial complexComparing with the ordinary building, the commercial complex is large and usually multi-functional. During the construction, new materials, technologies and structures are employed, which often bring about difficulties in its fire protection design.3.1 There are no applicable requirements for the fire protection design of the complex in the current national fire codeFor the fire protection design of a large commercial complex, the current national standard has covered the following points:（1）the building style and the distribution of business operations inside the complex;（2 ）the style of the indoor walking street;（3 ）how to determine the fire load of the complex;（4）if the walking street inside the complex can be used as a safe evacuation area? If yes, what kind of conditions should be provided;（5）the occupancy density, fire fighting equipment, smoke control pattern as well as other important design parameters;（6）the size and separation of the shops along the both sides of the walking street.3.2 There are limitations in the fire code for the fire designing of the large commercial complexHere just gives an example to illustrate the limitation. The requirements for the evacuation of the people in “Code for design of shop buildings”JGJ48-88 can’t meet the need of the evacuation system of the large commercial complex. Personnel convert quantity in JGJ48-88 is based on the business area and the area of the storage, which is totally unfit for the new layout of a complex with modern ideas and novelties. The evacuation width calculated according to the method given in JGJ48-88 is usually too big. As a result, more staircases will be required, which not only brings great difficulties in the designing of the evacuation system, but also create enormous waste. At the same time, the layout, structure as well as the aesthetic quality of the complex will be affected too.[68~70] Therefore, it is improper to determine the evacuation width or other parameters according to the calculation method given in the current standard.3.3 Some of the requirements in the current code can’t be implemented easily in the fire protection design of large commercial complex（1）Fire compartmenttion.It is required in the current fire code that the fire compartment of the commercial buildings shall not be larger than 5000m2. However, the building area of a large commercial complex is usually as big as hundreds of thousands of square meters. If the fire compartment is divided strictly according to the requirements of the fire code, many many fire compartments, staircases and exits will be provided. The result of this is that the arrangements of the business area will be greatly affected and the function of the complex will be completely limited.（2）Fire separation.The typical problem for the fire protection design of large commercial complex is that its travel distance and evacuation width can’t meet the requirements of the code.“Code for design of building fire protection and prevention”GB 50016-2006 requires that the linear distance between any point in the shopping areas inside the Class A and Class B buildings and the nearest exit should not be larger than 30m; when the building is protected completely by sprinkler system, the maximum safe travel distance shall be 37.5m; the end of the staircase on the first floor shall be provided with exit directly leading to outdoor or shall be enlarged. When the building is not more than 4 stories, the exit directly leading to outdoor can be located at the place that is not more than 15m away from the staircase. But in practice, it is not enough for large commercial complex to provide emergency staircases only at the periphery of the building because the complex is usually quite long and deep. Therefore, more staircases shall be provided in the middle. According to the requirements of the fire code, these staircases in the middle part of the building must have exits directly leading to the outdoor, which is completely out of the question.“Code for fire protection design of tall buildings” GB 50045-95(2005 edition) requires that the linear distance between any point in the shopping areas and the nearest exit should not be larger than 30m. In practice, the emergency staircases of the high-rise commercial buildings are also provided at the periphery of the building. The linear distance between the least favorable point to the nearest staircase is often larger than 30m. But in order to meet the requirement of the tall building code, staircases in the middle of the building must be provided. However, the staircases in the middle of the building can’t directly lead to outside.（3）Fire fighting.Both “Code for design of building fire protection and prevention”and “Code for fire protection design of tall buildings” require that wherethe length of the building along the street is more that 150m or the total length of the building is more than 220m, a well situated fire vehicle access shall be provided to cross the building. For large commercial complex, it is quite difficult to provide fire vehicle access to cut the building apart. Therefore, in practice, many designers propose to use the walking street as the fire vehicle access, but it can’t meet the fire fighting need of the fire vehicles.4.Current research status at home and abroadCurrently in China, the researches on the fire protection design of large commercial complex mainly focus on the analysis of some fire protection system.Zhao Hualiang analyzed the commonly used index and parameters of evacuation design. Parameters used for design of evacuation system of large commercial complex such as number of people, evacuation width, travel distance as well as emergency lighting have been discussed.Aim at the difficulties in designing of the fire partition in commercial construction, Zheng Yanqiu analyzed the general requirements for the design of the sunk plaza, fire compartment, protected evacuation passage and atrium. The application of cesium and kalium fire protection glass and toughened glass protected by water sprinkler as the fire partition was also studied.Guo Jinjun and Zhao Lijun introduced the difficulties in the designing of water based fire fighting systems as well as the solution.Guo Xiaolong and Wang Lingjian introduced a method to solve the problem of fire separation of a large commercial complex as well as atrium smoke extraction by separating inner atrium and horizontal sliding skylight.“Code for fire protection design of large commercial complex in Chongqing” provides a method to calculate the width of exit and series of parameters that are applicable for Chongqing city. In the code, theconcept of calculating the width of the exit based on the fire compartment was put forward for the first time. The requirements that the exit can be borrowed or shared by the adjoining fire compartments are provided and the calculation method to calculate this kind of exit is given. For the shopping malls with quite many stories above ground, this local code of Chongqing introduces the concept of “refuge space”, which provides favorable conditions for the emergent evacuation of the people.Aiming at the problems in the requirement of the fire code-“if the building area of an underground shopping mall is larger than 20000m2, fire wall shall be used to separate it and there shall be no openings in the fire wall”, Kang Dasheng and Wang Jinling suggested to provide a so-called “open fire isolating area” (sunk space) and “closed fire isolating area” . They also suggested to provide an emergency passageway less than 55m long on the first underground floor to directly lead to the outside of the building. For those large space areas like the atrium and indoor walking street, they suggested to install intelligent sprinkler system especially for large space areas.The above mentioned researches mainly focus on the problems in the design of the commercial buildings. Solutions from the experiences during design, review and construction have been proposed, but they are not complete and thorough. The results can’t be generalized.Some foreign building and fire codes have some requirements for the fire protection of commercial buildings. For example, building code of Canada, fire code of Singapore, building code of New Zealand and the “Uniform Building Code” of NFPA etc. However, these requirements are mainly applicable to ordinary shops, not the large commercial complexes in China.5. ConclusionIn order to solve so many practical problems encountered in the fire protection design of the large commercial complex, to evaluate the fire safety performance of this kind of building scientifically, and to define the scientific, reasonable and economic fire safety system, it is necessary to study the key technology of fire protection based on the practical fire loads and occupant density in the large commercial complex in China. Through this research, the related technical requirements of fire protection design were determined, and the scientific, reasonable and economical method of fire protection design was proposed. It is very important to understand the method and to prevent the occurrence of fire so as to safeguard the life safety and reduce property loss.References[1]Fire Bureau of MPS. Anthology of disastrous fire cases of China,2008.[2]LI Yin-qing. Performance Design for Building Fire Protection. Beijing: Chemical Industry Press.2005.141~171.[3]LI Yu. Study on Performance-based Fire Protection Design of Large Shopping Centre. MA thesis of Xi’an University of Architecture & Technology,2005.[4]ZOU He. The key technology research for performance-based design of underground commercial building. Engineering Master Degree Dissertation of Chongqing University,2007.[5]LI Xin, GU Yu. Discussion on the problems in the evacuation design of large commercial complex.. Fire Technology and Products Information,2007,12,31~33.[6]Chongqing Construction Committee. DBJ 50-054-2006 Code for fire protection design of large-scale commercial buildings of Chongqing,2006.[7]HUO Ran, YUAN Hong-yong. Performance-based Fire Protection Design and Analysis.Hefei:Anhui Science & Technology Publishing House, 2003.[8]ZHAO Wei. Evaluation of performance-based design on giant commercial building.Fire Science and Technology, 2009,28(11),817~819.[9]The Ministry of Public Security of the People’s Republic of China. GB50016-2006 Code of Design on Building Fire Protection and Prevention. Beijing: China Planning Press,2006.[10]The Ministry of Public Security of the People’s Republic of China. GB50045-95 Code for fire protection design of tall buildings(2005Edition).Beijing: China Planning Press,2005.[11]Civil Air Defence Office of China, The Ministry of Public Security of the People’s Republic of China. GB 50098-2009 Code for fire protection design of civil air defense works. Beijing:China Planning Press,2009.[12]Central-south Architectural Design Institute. Code for Design of Shop Buildings(draft) JGJ 48-88. Beijing:China Architecture & Building Press,1988.[13]LIN Feng. Studies on the Fire Safe of Large-scale Commercial Buildings. MA thesis of Xi’an University of Architecture & Technology,2009.[14]ZHAO Hua-liang. Discussion on Safe Evacuation from Commercial Buildings.Fire Technology and roducts Information,2005,2,9~11.[15]JING Jian-sheng, NI Zhao-peng, ZHUANG Jing-yi. Calculation method of the number of safe egress occupants in commercial building.Fire Science and Technology,2003,22(5),351~353.[16]ZHANG Shu-ping, JING Ya-jie. Research of evacuation crowd in the business hall of large department stores. Fire Science and Technology,2004,23(2),133~136.[17]QI Xiao-xia, PAN Jing. Research of evacuation crowd in the large specialized stores. Fire Science and Technology,2005,24(1),60~64.[18]YAN Xiao-long,WANG Ling-jian. Fire protection design of large-scale commercial building. Fire Science and Technology,2007.26(5),523~525.[19]ZHENG Yan-qiu. Analysis of fire protection separate design in commercial construction [J]. Fire Science and Technology,2009,28(1),43~46.[20]GUO Jin-jun, ZHAO Li-jun. Design difficulties and solutions for water fire-extinguishing system in the mall [J]. Water & Wastewater Engineering,2008,7(34),86~88.[21]GUO Sheng-you, LIU Mei-mei. Idea and characteristic of code for the fire prevention design of large-scale commercial buildings of Chongqing [J]. Fire Science and Technology, 2007, 26(1), 49~51.[22]KANG Da-sheng, WANG Jin-ling. The Measures of Large-Scale Shop Fire Prevention Designing [J]. Journal of Chinese People's Armed Police Force Academy,2008,24(10),15~17.[23]National Research Council of Canada.National Building Code of Canada[S].2005ˈVolume 1.[24]Singapore Civil Defence Force.Singapore Fire Code[S].[25]NFPA. NFPA1 Fire Code 2009 Edition[S],2009.[26]R.L.P. Custer & B. J. Meacham. Introduction To Performance based Fire Safety. National Fire Protection Association, Quincy, MA, 1997.[27]SFPE engineering guide to performance–based fire protection:analysis and design of buildings.First Edition,National Fire Protection Association,Society of Fire Protection Engineers,USA,2000.[28]British Standards Institution. Draft British standard BSDD240 fire safety engineering in building,Part l: Guide to the application office safety engineering Principles,1997.[29]Building Code of Australia, Australia Building Code Board, October 1996.[30]Hadjisophocleous GV,Benichou N.Development of performance-based codes, performance criteria and fire safety engineering methods.International Journal on Engineering Performance-based Fire Code, 2000, 2(4), 127~142.二、翻译结果分析与研究大型商业综合体中消防难点的设计摘要总结了大型商业综合体的火灾特性。

电气工程的外文文献(及翻译)文献一：Electric power consumption prediction model based on grey theory optimized by genetic algorithms本文介绍了一种基于混合灰色理论与遗传算法优化的电力消耗预测模型。

该模型使用时间序列数据来建立模型，并使用灰色理论来解决数据的不确定性问题。

通过遗传算法的优化，模型能够更好地预测电力消耗，并取得了优异的预测结果。

此模型可以在大规模电力网络中使用，并具有较高的可行性和可靠性。

文献二：Intelligent control for energy-efficient operation of electric motors本文研究了一种智能控制方法，用于电动机的节能运行。

该方法提供了一种更高效的控制策略，使电动机能够在不同负载条件下以较低的功率运行。

该智能控制使用模糊逻辑方法来确定最佳的控制参数，并使用遗传算法来优化参数。

实验结果表明，该智能控制方法可以显著降低电动机的能耗，节省电能。

文献三：Fault diagnosis system for power transformers based on dissolved gas analysis本文介绍了一种基于溶解气体分析的电力变压器故障诊断系统。

通过对变压器油中的气体样品进行分析，可以检测和诊断变压器内部存在的故障类型。

该系统使用人工神经网络模型来对气体分析数据进行处理和分类。

实验结果表明，该系统可以准确地检测和诊断变压器的故障，并有助于实现有效的维护和管理。

文献四：Power quality improvement using series active filter based on iterative learning control technique本文研究了一种基于迭代研究控制技术的串联有源滤波器用于电能质量改善的方法。

中文2795字第一部位译文部分变压器摘要：变压器是变电所的主要设备，功能是实现电网电压的等级变换，基本工作原理是电磁感应。

变配电所是实现电压等级变换和电能分配的场所。

对供电电源进行电压等级变换，应对电能进行重新分配的场所称为变电所。

建筑变电所是供配电系统的枢纽，供电电源由电网引到变电所，在变电所完成降压，电能分配等功能。

关键词:变电所；变压器；继电保护；1. 介绍要从远端发电厂送出电能，必须应用高压输电。

因为最终的负荷，在一些点高电压必须降低。

变压器能使电力系统各个部分运行在电压不同的等级。

本文我们讨论的原则和电力变压器的应用。

2. 双绕组变压器变压器的最简单形式包括两个磁通相互耦合的固定线圈。

两个线圈之所以相互耦合，是因为它们连接着共同的磁通。

在电力应用中，使用层式铁芯变压器(本文中提到的)。

变压器是高效率的，因为它没有旋转损失，因此在电压等级转换的过程中，能量损失比较少。

典型的效率范围在92到99%，上限值适用于大功率变压器。

从交流电源流入电流的一侧被称为变压器的一次侧绕组或者是原边。

它在铁圈中建立了磁通φ，它的幅值和方向都会发生周期性的变化。

磁通连接的第二个绕组被称为变压器的二次侧绕组或者是副边。

磁通是变化的；因此依据楞次定律，电磁感应在二次侧产生了电压。

变压器在原边接收电能的同时也在向副边所带的负荷输送电能。

这就是变压器的作用。

3. 变压器的工作原理当二次侧电路开路是，即使原边被施以正弦电压Vp ，也是没有能量转移的。

外加电压在一次侧绕组中产生一个小电流Iθ。

这个空载电流有两项功能：（1）在铁芯中产生电磁通，该磁通在零和±φm 之间做正弦变化，φm 是铁芯磁通的最大值；（2）它的一个分量说明了铁芯中的涡流和磁滞损耗。

这两种相关的损耗被称为铁芯损耗。

变压器空载电流Iθ一般大约只有满载电流的2%—5%。

因为在空载时，原边绕组中的铁芯相当于一个很大的电抗，空载电流的相位大约将滞后于原边电压相位90º。

附录A：英文参考文献及其翻译Direct torque controlDirect torque control(DTC) is one method used in variable frequency drives to control the torque (and thus finally the speed) of three-phaseAC electric motors. This involves calculating an estimate of the motor's magnetic flux and torque based on the measured voltage and current of the motor. MethodStatorflux linkage is estimated by integrating the stator voltages. Torque is estimated as a cross product of estimated stator flux linkagevector and measured motor currentvector. The estimated flux magnitude and torque are then compared with their reference values. If either the estimated flux or torque deviates from the reference more than allowed tolerance, the transistors of the variable frequency drive are turned off and on in such a way that the flux and torque will return in their tolerance bands as fast as possible. Thus direct torque control is one form of the hysteresis or bang-bang control.This control method implies the following properties of the control:∙Torque and flux can be changed very fast by changing the references∙High efficiency & low losses - switching losses are minimized because the transistors are switched only when it is needed to keep torque and flux within their hysteresisbands∙The step response has no overshoot∙No coordinate transforms are needed, all calculations are done in stationary coordinate system∙No separate modulator is needed, the hysteresis control defines the switch control signals directly∙There are no PI current controllers. Thus no tuning of the control is required∙The switching frequency of the transistors is not constant. However, by controlling the width of the tolerance bands the average switching frequency can be kept roughly atits reference value. This also keeps the current and torque ripple small. Thus thetorque and current ripple are of the same magnitude than with vector controlled drives with the same switching frequency.∙Due to the hysteresis control the switching process is random by nature. Thus there are no peaks in the current spectrum. This further means that the audible noise of themachine is low∙The intermediate DC circuit's voltage variation is automatically taken into account in the algorithm (in voltage integration). Thus no problems exist due to dc voltage ripple (aliasing) or dc voltage transients∙Synchronization to rotating machine is straightforward due to the fast control; Just make the torque reference zero and start the inverter. The flux will be identified by the first current pulse∙Digital control equipment has to be very fast in order to be able to prevent the flux and torque from deviating far from the tolerance bands. Typically the control algorithmhas to be performed with 10 - 30 microseconds or shorter intervals. However, theamount of calculations required is small due to the simplicity of the algorithm ∙The current and voltage measuring devices have to be high quality ones without noise and low-pass filtering, because noise and slow response ruins the hysteresis control ∙In higher speeds the method is not sensitive to any motor parameters. However, at low speeds the error in stator resistance used in stator flux estimation becomes criticalThe direct torque method performs very well even without speed sensors. However, the flux estimation is usually based on the integration of the motor phase voltages. Due to the inevitable errors in the voltage measurement and stator resistance estimate the integrals tendto become erroneous at low speed. Thus it is not possible to control the motor if the output frequency of the variable frequency drive is zero. However, by careful design of the control system it is possible to have the minimum frequency in the range 0.5 Hz to 1 Hz that is enough to make possible to start an induction motor with full torque from a standstill situation.A reversal of the rotation direction is possible too if the speed is passing through the zero range rapidly enough to prevent excessive flux estimate deviation.If continuous operation at low speeds including zero frequency operation is required, a speed or position sensor can be added to the DTC system. With the sensor, high accuracy of the torque and speed control can be maintained in the whole speed range.HistoryDirect torque control was patented by Manfred Depenbrock in U.S. Patent 4,678,248 filed originally on October 20, 1984 in Germany. He called it "Direct Self-Control" (DSC). However, Isao Takahashi and Toshihiko Noguchi presented a similar idea only few months later in a Japanese journal. Thus direct torque control is usually credited to all three gentlemen.The only difference between DTC and DSC is the shape of the path along which the flux vector is controlled to follow. In DTC the path is a circle and in DSC it was a hexagon. Today DTC uses hexagon flux path only when full voltage is required at high speeds.Since Depenbrock, Takahashi and Noguchi had proposed direct torque control (DTC) for induction machines in the mid 1980s, this new torque control scheme has gained much momentum. From its introduction, the Direct Torque control or Direct Self Control (DSC) principle has been used for Induction Motor (IM) drives with fast dynamics. Despite its simplicity, DTC is able to produce very fast torque and flux control, if the torque and flux are correctly estimated.Among the others, DTC/DSC was further studied in Ruhr-University in Bochum, Germany at the end of 80's. A very good treatment of the subject 。

外文资料翻译TRANSFORMER1. INTRODUCTIONThe high-voltage transmission was need for the case electrical power is to be provided at considerable distance from a generating station. At some point this high voltage must be reduced, because ultimately is must supply a load. The transformer makes it possible for various parts of a power system to operate at different voltage levels. In this paper we discuss power transformer principles and applications.2. TOW-WINDING TRANSFORMERSA transformer in its simplest form consists of two stationary coils coupled by a mutual magnetic flux. The coils are said to be mutually coupled because they link a common flux.In power applications, laminated steel core transformers (to which this paper is restricted) are used. Transformers are efficient because the rotational losses normally associated with rotating machine are absent, so relatively little power is lost when transforming power from one voltage level to another. Typical efficiencies are in the range 92 to 99%, the higher values applying to the larger power transformers.The current flowing in the coil connected to the ac source is called the primary winding or simply the primary. It sets up the flux φ in the core, which varies periodically both in magnitude and direction. The flux links the second coil, called the secondary winding or simply secondary. The flux is changing; therefore, it induces a voltage in the secondary by electromagnetic induction in accordance with Lenz’s law. Thus the primary receives its power from the source while the secondary supplies this power to the load. This action is known as transformer action.3. TRANSFORMER PRINCIPLESWhen a sinusoidal voltage V p is applied to the primary with the secondary open-circuited, there will be no energy transfer. The impressed voltage causes a small current Iθ to flow in the primary winding. This no-load current has two functions: (1) it produces the magnetic flux in the core, which varies sinusoidally between zero and φm, where φm is the maximum value of the core flux; and (2) it provides a component to account for the hysteresis and eddy current losses in the core. There combined losses are normally referred to as the core losses.The no-load current Iθ is usually few percent of the rated full-load current of the transformer (about 2 to 5%). Since at no-load the primary winding acts as a large reactance due to the iron core, the no-load current will lag the primary voltage by nearly 90º. It is readily seen that the current component I m= I0sinθ0, called the magnetizing current, is 90º in phase behind the primary voltage V P. It is this component that sets up the flux in the core; φ is therefore in phase with I m.The second component, I e=I0sinθ0, is in phase with the primary voltage. It is the current component that supplies the core losses. The phasor sum of these twocomponents represents the no -load current, ore m o I I I +=It should be noted that the no -load current is distortes and nonsinusoidal. This is the result of the nonlinear behavior of the core material.If it is assumed that there are no other losses in the transformer, the induced voltage In the primary, E p and that in the secondary, E s can be shown. Since the magnetic flux set up by the primary winding ，there will be an induced EMF E in the secondary winding in accordance with Faraday’s law, namely, t N E ∆∆⋅=/ϕ. This same flux also links the primary itself, inducing in it an EMF, E p . As discussed earlier, the induced voltage must lag the flux by 90º, therefore, they are 180º out of phase with the applied voltage. Since no current flows in the secondary winding, E s =V s . The no -load primary current I 0 is small, a few percent of full -load current. Thus the voltage in the primary is small and V p is nearly equal to E p . The primary voltage and the resulting flux are sinusoidal; thus the induced quantities E p and E s vary as a sine function. The average value of the induced voltage given byE avg = turns× change in flux in a given time given timewhich is Faraday’s law applied to a finite time interval. It follows thatE avg = N 21/(2)m f ϕ = 4fNφm which N is the number of turns on the winding. Form ac circuit theory, the effective or root -mean -square (rms) voltage for a sine wave is 1.11 times the average voltage; thusE = 4.44fNφmSince the same flux links with the primary and secondary windings, the voltage per turn in each winding is the same. HenceE p = 4.44fN p φmandE s = 4.44fN s φmwhere E p and Es are the number of turn on the primary and secondary windings, respectively. The ratio of primary to secondary induced voltage is called the transformation ratio. Denoting this ratio by a, it is seen that a = p sE E = p s N N Assume that the output power of a transformer equals its input power, not a bad sumption in practice considering the high efficiencies. What we really are saying is that we are dealing with an ideal transformer; that is, it has no losses. ThusP m = P outorV p I p × primary PF = V s I s × secondary PFwhere PF is the power factor. For the above -stated assumption it means that the power factor on primary and secondary sides are equal; thereforeV p I p = V s I sfrom which is obtained p s V V = p s I I ≌ p sE E ≌ a It shows that as an approximation the terminal voltage ratio equals the turns ratio. The primary and secondary current, on the other hand, are inversely related to the turns ratio. The turns ratio gives a measure of how much the secondary voltage is raised or lowered in relation to the primary voltage. To calculate the voltage regulation, we need more information.The ratio of the terminal voltage varies somewhat depending on the load and its power factor. In practice, the transformation ratio is obtained from the nameplate data, which list the primary and secondary voltage under full -load condition.When the secondary voltage V s is reduced compared to the primary voltage, the transformation is said to be a step -down transformer: conversely, if this voltage is raised, it is called a step -up transformer. In a step -down transformer the transformation ratio a is greater than unity (a>1.0), while for a step -up transformer it is smaller than unity (a<1.0). In the event that a=1, the transformer secondary voltage equals the primary voltage. This is a special type of transformer used in instances where electrical isolation is required between the primary and secondary circuit while maintaining the same voltage level. Therefore, this transformer is generally knows as an isolation transformer.As is apparent, it is the magnetic flux in the core that forms the connecting link between primary and secondary circuit. In section 4 it is shown how the primary winding current adjusts itself to the secondary load current when the transformer supplies a load.Looking into the transformer terminals from the source, an impedance is seen which by definition equals V p / I p . From p s V V = p s I I ≌ p sE E ≌ a , we have V p = aV s and I p = I s /a.In terms of V s and I s the ratio of V p to I p isp p V I = /s s aV I a= 2s s a V I But V s / I s is the load impedance Z L thus we can say thatZ m (primary) = a 2Z LThis equation tells us that when an impedance is connected to the secondary side, it appears from the source as an impedance having a magnitude that is a 2 times its actual value. We say that the load impedance is reflected or referred to the primary. It is this property of transformers that is used in impedance -matching applications.译文变压器1. 介绍要从远端发电厂送出电能，必须应用高压输电。

毕业设计英文文献翻译(电力方向附带中文)大学毕业设计英文文献翻译,关于电力系统方向,电力谐波!绝对原创!HarmonicsService reliability and quality of power have become growing concerns for many facility managers, especially with the increasing sensitivity of electronic equipment and automated controls. There are several types of voltage fluctuations that can cause problems, including surges and spikes, sags, harmonic distortion, and momentary disruptions. Harmonics can cause sensitive equipment to malfunction and other problems, including overheating of transformers and wiring, nuisance breaker trips, and reduced power factor.What Are Harmonics?Harmonics are voltage and current frequencies riding on top of the normal sinusoidal voltage and current waveforms. Usually these harmonic frequencies are in multiples of the fundamental frequency, which is 60 hertz (Hz) in the US and Canada. The mostcommon source of harmonic distortion is electronic equipment using switch-mode power supplies, such as computers, adjustable-speed drives, and high-efficiency electronic light ballasts.Harmonics are created by these Dswitching loads‖ (also called “nonlinear loads,‖ because current does not vary smoothly with voltage as it does with simple resistive and reactive loads): Each time the current is switched on and off, a current pulse is created. The resulting pulsed waveform is made up of a spectrum of harmonic frequencies, including the 60 Hz fundamental and multiples of it. This voltage distortion typically results from distortion in the current reacting with system impedance. (Impedance is a measure of the total opposi tion―resistance, capacitance, and inductance―to the flow of an alternating current.) The higher-frequency waveforms, collectively referred to as total harmonic distortion (THD), perform no useful work and can be asignificant nuisance.Harmonic waveforms are characterized by their amplitude and harmonic number. In the U.S. and Canada, the third harmonic is 180 Hz―or 3 x 60 Hz―and the fifth harmonic is 300 Hz (5 x 60Hz). The third harmonic (and multiples of it) is the largest problem in circuits with single-phase loads such as computers and fax machines. Figure 1 shows how the 60-Hz alternating current (AC) voltage waveform changes when harmonics are added.大学毕业设计英文文献翻译,关于电力系统方向,电力谐波!绝对原创!The Problem with HarmonicsAny distribution circuit serving modern electronic devices will contain some degree of harmonic frequencies. The harmonics do not always cause problems, but the greater the power drawn by these modern devices or other nonlinear loads, the greater the level of voltage distortion. Potential problems (or symptoms of problems) attributed to harmonics include:■ Malfunction of sensitive equipment■ Random tripping of circuit breakers■ Flickering lights■ Very high neutral currents■ Overheated phase conductors, panels, and transformers ■ Premature failure of transformers and uninterruptible power supplies (UPSs)■ Reduced power factor■ Reduced system capacity (because harmonics create additional heat, transformers and otherdistribution equipment cannot carry full rated load)Identifying the ProblemWithout obvious symptoms such as nuisance breaker trips or overheated transformers, how do you determine whether harmonic current or voltages are a cause for concern? Here are several suggestions for simple, inexpensive measurements that a facility manager or staff electrician could take, starting at the outlet and moving upstream:■ Measure the peak and root mean square (RMS) voltage at a sample of receptacles. The Dcrest factor‖ is the ra tio of peak to RMS voltage. For a perfectly sinusoidal voltage, the crest factor will be 1.4. Low crest factor is a clear indicator of the presence of harmonics. Note that these measurements must be performed with a Dtrue RMS‖ meter―one that doesn‘t assume a perfectly sinusoidal waveform.■ Inspect distribution panels. Remove panel covers and visually inspect components for signs of overheating, including discolored or receded insulation or discoloration of terminal screws. If you see any of these symptoms, check that connectionsare tight (since loose connections could also cause overheating), and compare currents in all conductors to their ratings.■ Measure phase and neutral currents at the transformer secondary with clamp-on current probes. If no harmonics are being generated, the neutral current of a three-phase distribution system carries only the imbalance of the phase currents. In a well-balanced three-phase distribution system, phase currents will be very similar, and current in the neutral conductor should be much lower than phase current and far below its rated current capacity. If phase currents are similar and neutral current exceeds their imbalance by a wide margin, harmonics are present. If neutral current is above 70 percent of the cond uctor‘s rated capacity, you need to mitigate the problem.■Compare transformer temperature and loading with nameplate temperature rise and capacity ratings. Even lightly loaded transformers can overheat if harmonic current is high. A transformer that is near or over its rated temperature rise but is loaded well below its rated capacity is a clear sign that harmonics are at work. (Many transformers have built-in temperature gauges. If yours does not, infrared thermography can be used to detect overheating.)大学毕业设计英文文献翻译,关于电力系统方向,电力谐波!绝对原创!In addition to these simple measurements, many power-monitoring devices are now commercially available from a variety of manufacturers to measure and record harmonic levels. These instruments provide detailed information on THD, as well as on the intensity of individual harmonic frequencies. After taking the appropriate measurements to determine whether you have high levels of harmonics and, if so, to find the source, you will be well-positioned to choose the best solution.Solutions to Harmonics ProblemsThe best way to deal with harmonics problems is through prevention: choosing equipment and installation practices that minimize the level of harmonics in any one circuit or portion of a facility. Many power quality problems, including those resulting from harmonics, occur when new equipment is haphazardly added to older systems. However, even within existing facilities, the problems can often be solved with simple solutions such as fixing poor or nonexistent grounding on individual equipment or the facility as a whole, moving a few loads between branch circuits, or adding additional circuits to help isolate the sensitiveequipment from what is causing the harmonic distortion. If the problems cannot be solved by these simple measures, there are two basic choices: to reinforce the distribution system to withstand the harmonics or to install devices to attenuate or remove the harmonics. Reinforcing the distribution system means installing double-size neutral wires or installing separate neutral wires for each phase, and/or installing oversized or Krated transformers, which allow for more heat dissipation. There are also harmonic-rated circuit breakers and panels, which are designed to prevent overheating due to harmonics. This option is generally more suited to new facilities, because the costs of retrofitting an existing facility in this way could be significant. Strategies for attenuating harmonics, from cheap to more expensive, include passive harmonic filters, isolation transformers, harmonic mitigating transformers (HMTs), the Harmonic Suppression System (HSS) from Harmonics Ltd., and active filters(Table 1).Passive filters (also called traps) include devices that provide low-impedance paths to divert harmonics to ground and devices that create a higher-impedance path to discourage the flow of harmonics. Both of these devices, by necessity, change theimpedance characteristics of the circuits into which they are inserted. Another weakness of passive harmonic technologies is that, as their name implies, they cannot adapt to changes in the electrical systems in which they operate. This means that changes to the electrical system (for example, the addition or removal of power factorCcorrection capacitors or the addition of more nonlinear loads) could cause them to be overloaded or to create Dresonances‖ that could actually amplify, rather than diminish, harmonics.Active harmonic filters, in contrast, continuously adjust their behavior in response to the harmonic current content of the monitored circuit, and they will not cause resonance. Like an automatic transmission in a car, active filters are designed to accommodate a full range of expected operating conditions upon installation, without requiring further adjustments by the operator.Isolation transformers are filtering devices that segregate harmonics in the circuit in which they are created, protecting upstream equipment from the effects of harmonics. These transformers do not remove the problem in the circuit generating the harmonics, but they can prevent the harmonics from affecting more sensitive equipment elsewhere within the facility.大学毕业设计英文文献翻译,关于电力系统方向,电力谐波!绝对原创!Harmonic mitigating transformers actually do relieve problematic harmonics. HMTs can be quite cost-effective in the right application, because they can both improve reliability and reduce energy costs. The right application includes transformers that are heavily or moderately loaded and where high levels of harmonic currents are present. In addition, HMTs are very effective in supporting critical loads that are backed up by a UPS. UPSs and backup generators tend to have high impedance, which results in high voltage distortion under nonlinear loading. Because of this, equipment that operates flawlessly when supplied by utility power may malfunction when the backup system engages during a utility outage. Note that some of these power systems have output filters (either passive or active) to control harmonic levels. The presence or absence of such filters should be determined before adding an HMT.The Harmonics Ltd. Harmonic Suppression System is a unique solution for single-phase loads that is designed to suppress the third harmonic. An HSS is generally more expensive than an HMT, but it is designed to attenuate the harmonicsproblems throughout the entire distribution system, not just upstream of the transformer. The types of facilities that present the best opportunities for HSS installation are those that place a very high premium on power quality and reliability, such as server farms, radio and television broadcast studios, and hospitals. (See .) Economic EvaluationEvaluating the life-cycle costs and effectiveness of harmonics mitigation technologies can be ve ry challenging―beyond the expertise of most industrial facility managers. After performing the proper measurement and analysis of the harmonics problem, this type of evaluation requires an analysis of the costs of the harmonics problem (downtime of sensitive equipment, reduced power factor, energy losses or potential energy savings) and the costs of the solutions. A good place to start in performing this type of analysis is to ask your local utility or electricity provider for assistance. Many utilities offer their own power quality mitigation services or can refer you to outside power quality service providers.Additional ResourcesInstitute of Electrical and Electronics Engineers (IEEE),Standard 519-1992, DIEEE大学毕业设计英文文献翻译,关于电力系统方向,电力谐波!绝对原创!Recommended Practices and Requirements for Harmonic Control in Electric Power Systems‖ (1992), available at .Relationship between harmonics and symmetrical componentsAbstract New terminology is introduced to make clear the relationship between harmonics and symmetrical components. Three-phase sets are classified in terms of symmetrical sets and asymmetrical sets. Subclasses are introduced with the names symmetrical balanced sets, symmetrical unbalanced sets, asymmetrical balanced sets and asymmetrical unbalanced sets to show that a threephase set can resolve to either one, two or three symmetrical component sets. The results from four case studies show that these subclasses and their resolution to symmetrical component sets improve understanding of harmonic analysis of systems having balanced and unbalanced harmonic sources and loads.Keywords asymmetrical sets; harmonic flows; harmonic sources; symmetrical component sets; symmetrical sets Any periodic wave shape can be broken down into oranalysed as a fundamentalwave and a series of harmonics.Three-phase harmonic analysis requires a clear understanding of the relationship between symmetrical component injections from harmonic sources (e.g. adjustable speed drives, ASDs) and their relationship to harmonic flows (symmetrical components) arising from the application of a harmonic source to a linear system.Alimited number of references contain brief information concerning harmonics and symmetrical components. Reference 1, provides a paragraph on this topic and uses the heading Relationship between Harmonics and Symmetrical Components‘.It includes a table that is supported by a brief explanatory paragraph. The table expresses harmonics in terms of positive, negative and zero sequences. It states that these sequences are for harmonics in balanced three-phase systems. The heading refers to symmetrical components while the content refers to balanced three-phase systems. Herein lies the anomaly. Classically, symmetrical components (especially ero sequence) are only applied in unbalanced systems. The following questions rose after reading the Ref. 1 paragraph.(a)Do symmetrical components (especially zero sequence), in the classical sense,apply in balanced as well as unbalanced non-sinusoidal systems and is this abreak from tradition?(b)What do the terms, symmetrical, asymmetrical, balanced, unbalanced andsymmetrical components mean?(c)What are the conditions under which a system must operate so that harmonicsresolve to positive, negative and zero sequences and is the table given inRef. 1 correct?The terminology used is found inadequate for describing non-sinusoidal systems.There is thus a need to introduce a three-phase terminology that will show the relationship and make the comparison between injections (currents) and harmonic flows (voltages and currents) meaningful.References 3 provides the basis for the solution by providing definitions for threephase sets‘, symmetrical sets‘an d symmetricalcomponent sets‘.The purpose of this paper is to introduce an approach to harmonic analysis大学毕业设计英文文献翻译,关于电力系统方向,电力谐波!绝对原创!based on the classification of three-phase sets and to make to comparison between injections from harmonic sources and corresponding harmonic flows quantifiable by expressing the results in terms of the number of symmetrical component sets found.Harmonic flows and their resolution to symmetrical components depends upon the magnitudes and phase sequences of the injections from a harmonic source, on the system‘s sequence impedances, on three- and four-wire connections and on whether the customer‘s linear load on the system is balanced or unbalanced. Therefore, what is injected in terms of symmetrical component sets by a harmonic source is not necessarily received by the system, i.e. the harmonic flows may resolve to one, two or three symmetrical component sets and this depends upon the type of three-phase set found. Therefore, any three-phase harmonic may be partially made up of any of thesymmetrical component sets.Four case studies are reported and they show a novel method for teaching the flow of power system harmonics. It is important to use case studies as part of one‘s teaching as they link learning to concepts and improve understanding. They show how the method of symmetrical components can be extended to a system‘s response to harmonic flows. When taught as a group, the four case studies improve cognitive skills by showing that the symmetrical component responses under unbalanced situations are different to the balanced state.IEEE __TIONS ON POWER __NICS VOL.19,NO.3,__年大学毕业设计英文文献翻译,关于电力系统方向,电力谐波!绝对原创!谐波服务的可靠性和电能质量已成为越来越多设施经理的关注，尤其是随着电子设备和自动化控制灵敏度提高了很多。