電力系統(tǒng)外文翻譯3

1、<p><b>　　外文資料翻譯</b></p><p>　　Electric Power System</p><p>　　Introduction</p><p>　　Electric Power System, components that transform other types of energy into electr

2、ical energy and transmit this energy to a consumer. The production and transmission of electricity is relatively efficient and inexpensive, although unlike other forms of energy, electricity is not easily stored and thus

3、 must generally be used as it is being produced.</p><p>　　Components of an Electric Power System</p><p>　　A modern electric power system consists of six main components:(1)the power station,(2)a

4、 set of transforms to raise the generated power to the high voltages used on the transmission lines,(3)the transmission,(4)the substations at which the power is stepped down to the voltage on the distribution lines,(5) t

5、he distribution lines, and(6)the transformers that lower the distribution voltage to the level used by the consumer's equipment.</p><p>　　Power Station The power station of a power system consists of

6、a prime mover, such as a turbine driven by water, steam, or combustion gases that operate a system of electric motors and generators. Most of the world's electric power is generated in steam plants driven by coal, oi

7、l, nuclear energy or gas. A smaller percentage of the world's electric power is generated by hydro electric (waterpower), diesel, and internal-combustion plants.</p><p>　　Transformers Modern electr

8、ic power systems use transformers to convert electricity into different voltages. With transformers, each stage of the system can be operated at an appropriate voltage. In a typical system, the generators at the power st

9、ation deliver a voltage of from 1,000 to 26,000 volts (V). Transformers step this voltage up to values ranging from 138,000 to 765,000 V for the long-distances. At the substation the voltage may be transformed down to le

10、vels of 69,000 to 138,000 V fo</p><p>　　Transmission Lines The lines of high-voltage transmission systems are usually composed of wires of copper, aluminum, or copper-clad or aluminum-clad steel, which are

11、suspend from tall latticework towers of steel by strings of porcelain insulators. By the use of clad steel wires and high towers, the distance between towers can be increased, and the cost of the transmission line thus r

12、educed. In modern installations with essentially straight paths, high-voltage lines may be built with as few as s</p><p>　　For lower voltage distribution lines, wooden poles are generally used rather than st

13、eel towers. In cities and other areas where open lines create a safety hazard or are considered unattractive, insulated underground cables are used for distribution. Some of these cables have a hollow core through which

14、oil circulates under low pressure. The oil provides temporary protection from water damage to the enclosed wires should the cable develop a leak. Pipe-type cables in which three cables are enclose</p><p>　　S

15、upplementary Equipment Any electric-distribution system involves a large amount of supplementary equipment to protect the generators, transforms, and the transmission lines themselves. The system often includes devices

16、 designed to regulate the voltage or other characteristics of power delivered to consumers.</p><p>　　To protect all elements of a power system from short circuits and overloads, and for normal switching oper

17、ations, circuit breakers are employed. These breakers are large switches that are activated automatically in the event of a short circuit or other condition that produces a sudden rise of current. Because a current forms

18、 across the terminals of the circuit breaker at the moment when the current is interrupted, some large breakers (such as those used to protect a generator or a section of pri</p><p>　　Power Failures</p>

19、;<p>　　In most parts of the world, local or national electric utilities have joined in grid systems. The linking grids allow electricity generated in one area to be shared with others. Each utility that agrees to

20、share gains an increased reserve capacity, use of larger, more efficient generators, and the ability to respond to local power failures by obtaining energy from a linking grid.</p><p>　　These interconnected

21、grids are large, complex systems that contain elements operated by different groups. These systems offer the opportunity for economic savings and improve overall reliability but can create a risk of widespread failure. F

22、or example, the worst blackout in the history of the United States and Canada occurred August 14, 2003, when 61,800 megawatts of electrical power was lost in an area covering 50 million people.(One megawatt of electricit

23、y is roughly the amount needed to power</p><p>　　Despite the potential for rare widespread problems, the interconnected grid system provides necessary backup and alternate paths for power flow, resulting in

24、much higher overall reliability than is possible with isolated systems .National or regional grids can also cope with unexpected outage such as those caused by storms, earthquakes, landslides, and forest fires, or due to

25、 human error or deliberate acts of sabotage.</p><p>　　Power Quality</p><p>　　In recent years electricity has been used to power more sophisticated and technically complex manufacturing processes

26、, computers and computer networks, and a variety of other high-technology consumer goods. These products and processes are sensitive not only to the continuity of power supply but also to the constancy of electrical freq

27、uency and voltage. Consequently, utilities are taking new measures to provide the necessary reliability and quality of electrical power, such as by providing addit</p><p>　　Voltage Regulation Long transmi

28、ssion lines have considerable inductance and capacitance. When a current flows through the line, inductance and capacitance have the effect of varying the voltage on the line as the current varies. Thus the supply voltag

29、e varies with the load. Several kinds of devices are used to overcome this undesirable variation in an operation called regulation of the voltage. The device include induction regulators and three-phase synchronous motor

30、s (called synchronous cond</p><p>　　Inductance and capacitance react with a tendency to nullify one another. When a load circuit has more inductive than capacitive reactance, as almost invariably occurs in l

31、arge power systems, the amount of power delivered for a given voltage and current is less than when the two are equal. The ratio of these two amounts of power is called the power factor. Because transmission-line losses

32、are proportional to current, capacitance is added to the circuit when possible, thus bringing the power facto</p><p>　　World Electric Power Production Over the period from 1950 to 2003, the most recent ye

33、ar for which data are available, annual world electric power production and consumption rose from slightly less than 1 trillion kilowatt-hours (kW.h) to 15.9 trillion kW.h. A change also took place in the type of power g

34、eneration. In 1950 about two-thirds of the world’s electricity came from steam-generating sources and about one-third from hydroelectric sources. In 2003 thermal sources produced 65 percent of</p><p>　　Conse

35、rvation</p><p>　　Much of the world’s electricity is produced from the use of nonrenewable resources, such as natural gas, coal, oil, and uranium. Coal, oil, and natural gas contain carbon, and burning these

36、fossil fuels contributes to global emissions of carbon dioxide and other pollutants. Scientists believe that carbon dioxide is the principal gas responsible for global warming, a steady rise in Earth’s surface temperatur

37、e.</p><p>　　Consumers of electricity can save money and help protect the environment by eliminating unnecessary use of electricity, such as turning off light when leaving a room. Other conservation methods i

38、nclude buying and using energy-efficient appliances and light bulbs, and using appliances, such as washing machines and dryers, at off-peak production hours when rates are lower. Consumers may also consider environmental

39、 measures such as purchasing “green power” when it is offered by a local utility. ”Gr</p><p><b>　　電力系統(tǒng)</b></p><p><b>　　介紹</b></p><p>　　電力系統(tǒng)把其它形式的能源轉(zhuǎn)化為電能并輸送給用

40、戶。盡管不同于其它形式的能源，電能不容易儲(chǔ)存，一旦生產(chǎn)出來(lái)，必須得到使用，但是電力的生產(chǎn)和傳輸相對(duì)高效和廉價(jià)。</p><p><b>　　電力系統(tǒng)的組成</b></p><p>　　當(dāng)今的電力系統(tǒng)由六個(gè)主要部分組成：電站，升壓變壓器（將發(fā)出來(lái)的電升壓至傳輸線所需高電壓），傳輸線，變電站（電壓降至配電線電壓等級(jí)），配電線路和降壓變壓器（將配電電壓降至用戶設(shè)備使用的電壓

41、水平）。 </p><p>　　電站 電力系統(tǒng)的電站包括原動(dòng)機(jī)，如由水，蒸汽驅(qū)動(dòng)的渦輪，或者燃燒氣體操控的電動(dòng)機(jī)和發(fā)電機(jī)系統(tǒng)，世界上大多數(shù)的電能由煤炭、石油、核能或者燃?xì)怛?qū)動(dòng)的蒸汽發(fā)電廠產(chǎn)生。少量電能由水力，柴油和內(nèi)燃機(jī)發(fā)電廠產(chǎn)生。</p><p>　　變壓器 現(xiàn)代電力系統(tǒng)使用變壓器把電能轉(zhuǎn)換為不同的電壓。有了變壓器，系統(tǒng)的每個(gè)階段都能在合適的電壓等級(jí)下運(yùn)行。在典型的系統(tǒng)中，電站發(fā)電

42、機(jī)發(fā)出的電壓范圍是1000伏到26000伏。變壓器把電壓升至138000到765000伏后，送至主傳輸線上。因?yàn)閷?duì)于長(zhǎng)距離傳輸，電壓越高，效率越高。在變電站，電壓被降至69000到138000伏，以便在配電系統(tǒng)中傳輸。另外一組變壓器把電壓進(jìn)一步降至配電等級(jí)，如2400到4160伏，或者15，27，33KV。最終，在使用端，經(jīng)配電變壓器，電壓再次被降至240V或120V。 </p><p>　　傳輸線 高壓傳輸系

43、統(tǒng)通常由銅線、鋁線或者鍍銅、鍍鋁的鋼線組成，它們懸掛在高大鋼格構(gòu)塔架上成串的</p><p>　　瓷質(zhì)絕緣體上。由于含鍍層鋼線和鐵塔的使用，增大了塔與塔之間的距離，降低了傳輸線的成本。在當(dāng)前的直線安裝中，每公里高壓線只需建立6個(gè)鐵塔。在一些地區(qū)，高壓線懸掛于距離較近的木質(zhì)電線桿上。</p><p>　　對(duì)于低壓配電線路，更多的使用木質(zhì)電線桿，而不是鐵塔。在城市和一些地區(qū)，明線存在安全危險(xiǎn)或

44、者被認(rèn)為影響美觀，所以使用絕緣地下電纜進(jìn)行配電。一些電纜內(nèi)核中空，供低壓油循環(huán)。油可以為防止水對(duì)封閉線路的破壞提供臨時(shí)保護(hù)。通常使用管式電纜，三根電纜放入線管中，并填滿高壓油。這些電纜用于傳輸高達(dá)345KV的電流。</p><p>　　輔助設(shè)備 每個(gè)配電系統(tǒng)包含大量輔助設(shè)備來(lái)保護(hù)發(fā)電機(jī)、變壓器和傳輸線。系統(tǒng)通常還包括用來(lái)調(diào)整電壓或用戶端其它電力特性的設(shè)備。</p><p>　　為了保護(hù)電

45、力系統(tǒng)設(shè)施，防止短路和過(guò)載，對(duì)于正常的開關(guān)操作，采用斷路器。斷路器是大型開關(guān)，在短路時(shí)或者電流突然上升的情況下自動(dòng)切斷電源。由于電流斷開時(shí)，斷路器觸點(diǎn)兩端會(huì)形成電流，一些大型斷路器（如那些用來(lái)保護(hù)發(fā)電機(jī)和主輸電線的斷路器）通常浸入絕緣液體里面，如</p><p>　　油，以熄滅電流。在大型空氣開關(guān)和油斷路器中，使用磁場(chǎng)來(lái)削弱電流。小型空氣開關(guān)用于商場(chǎng)，工廠和現(xiàn)代家庭設(shè)備的保護(hù)。在住宅電氣布線中，以前普遍采用保險(xiǎn)絲

46、。保險(xiǎn)絲由熔點(diǎn)低的合金組成，安裝在電路中，當(dāng)電流超過(guò)一定值，它會(huì)熔斷，切斷電路?，F(xiàn)在絕大多數(shù)住宅使用空氣斷路器。</p><p><b>　　供電故障</b></p><p>　　世界上大多數(shù)地方，局部或全國(guó)電力設(shè)施都連成電網(wǎng)。電網(wǎng)可以使發(fā)電實(shí)現(xiàn)區(qū)域共享。同意共享的每個(gè)電力企業(yè)可以獲得不斷增加的儲(chǔ)備功率，使用更大、效率更高的發(fā)電機(jī)，從電網(wǎng)中獲取電能以應(yīng)對(duì)局部電力故障。

47、</p><p>　　互聯(lián)的電網(wǎng)是大型復(fù)雜系統(tǒng)，包括被不同組織操控的部分。這些系統(tǒng)可以節(jié)約開支，提高整體可靠性，但是也帶來(lái)了大范圍停電的風(fēng)險(xiǎn)。例如，2003年8月14日，美國(guó)和加拿大發(fā)生了歷史上最嚴(yán)重的停電事故。當(dāng)時(shí)，這個(gè)區(qū)域61800兆瓦的電力供應(yīng)中斷，五千萬(wàn)人口受到影響。（一兆瓦大約可以滿足750居民的用電需求）。停電事件迫切要求更新老化設(shè)備，提出關(guān)于全國(guó)電網(wǎng)可靠性的問(wèn)題。</p><p&

48、gt;　　盡管存在大范圍停電危險(xiǎn)，互聯(lián)電網(wǎng)提供了必要的備份措施和供替換的線路，相對(duì)于孤立系統(tǒng)，其整體可靠性要高得多。國(guó)家或地區(qū)電網(wǎng)還可以應(yīng)對(duì)由暴風(fēng)雨、地震、泥石流、森林火災(zāi)、人員操作錯(cuò)誤或者蓄意破壞造成的意外停電。</p><p><b>　　供電質(zhì)量</b></p><p>　　近年來(lái)，越來(lái)越多的精密復(fù)雜生產(chǎn)過(guò)程、計(jì)算機(jī)和網(wǎng)絡(luò)及許多高科技消費(fèi)品都使用電力為其提供能量

49、。這些產(chǎn)品和生產(chǎn)過(guò)程對(duì)于供電的連續(xù)性和電壓、頻率的恒定性很敏感。于是，相關(guān)部門正采取新措施來(lái)保證供電的可靠性和質(zhì)量。如提供附加的電氣設(shè)備來(lái)保證電壓和電能其它特性保持恒定。</p><p>　　電壓調(diào)整 長(zhǎng)距離傳輸線存在的電感和電容不容忽視。當(dāng)電流流過(guò)線路時(shí)，隨著電流的變化，電感和電容會(huì)對(duì)線路電壓產(chǎn)生影響。這樣，供電電壓會(huì)隨負(fù)荷變化。運(yùn)行中，有幾種設(shè)備用來(lái)克服這個(gè)波動(dòng)，被稱為電壓調(diào)整。這些設(shè)備包括感應(yīng)調(diào)節(jié)器、三相

50、同步機(jī)（也稱同步調(diào)相機(jī)），它們能夠改變傳輸線路中的電感和電容的有效量。 </p><p>　　電感和電容作用能相互抵消。當(dāng)負(fù)載電流感性電抗大于容性電抗時(shí)，這種情況總是出現(xiàn)在大型電力系統(tǒng)中，對(duì)于給定的電壓和電流，傳送的功率小于兩者相等的時(shí)候。這兩個(gè)量功率之比稱為功率因數(shù)。由于傳輸線損耗和電流成比例，如果可能，將在電路中使用電容，這樣功率因數(shù)盡可能接近于1。正是這個(gè)原因，在電力傳輸系統(tǒng)中，經(jīng)常使用大型電容器。<

51、;/p><p>　　世界電力生產(chǎn) 從1950年到2003年，最近一年的可用數(shù)據(jù)顯示，每年世界電力生產(chǎn)和消費(fèi)從小于1萬(wàn)億千瓦時(shí)增長(zhǎng)到15.9萬(wàn)億千瓦時(shí)。同樣，發(fā)電類型也發(fā)生了變化。在1950年，世界電力約2/3來(lái)自蒸汽源，約1/3 來(lái)自水電。2003年，熱源生產(chǎn)65%的電能，水電卻降至17%，核電占總量的16%。出于安全的考慮，在一些國(guó)家，特別是美國(guó)，核能的增長(zhǎng)緩慢。2003年，美國(guó)電能的20%來(lái)自核電廠；在世界領(lǐng)先

52、的法國(guó)，這個(gè)數(shù)字是78%。</p><p><b>　　保護(hù)</b></p><p>　　世界上大多數(shù)電能的生產(chǎn)來(lái)自天然氣、煤炭、石油和鈾等不可再生資源。煤炭、石油、天然氣含有碳元素，它們的燃燒加劇了二氧化碳和其它污染物的排放。科學(xué)家們認(rèn)為，二氧化碳是導(dǎo)致全球變暖，地球表面溫度上升的主要因素。</p><p>　　電力用戶通過(guò)節(jié)約用電，如離開房