電力系統(tǒng)的演化外文翻譯

1、<p><b>　　中文2188字</b></p><p>　　EVOLUTION OF ELECTRIC POWER SYSTEMS</p><p>　　The commercial use of electricity began in the late1870s when arc lamps were used for lighthouse illum

2、ination and street lighting.</p><p>　　The first complete electric power system (comprising a generator, cable, fuse, meter, and loads)was built by Thomas Edison-the historic Pearl Street Station in New York

3、City which began operation in September 1882.This was a dc system consisting of a steam-engine-driven dc generator supplying power to 59 customers within an area roughly 1.5km in radios. The load, which consisted entirel

4、y of incandescent lamps, was supplied at 110 V through an underground cable system. Within a few years similar </p><p>　　In spite of the initial widespread use of dc systems, they were almost completely supe

5、rseded by ac systems. By 1886, the limitations of dc systems were becoming increasingly apparent .They could deliver power only a short distance from the generators. To keep transmission power losers (RI2) and voltage dr

6、ops to acceptable levels, voltage levels had to be high for long-distance power transmission. Such high voltages were not acceptable for generation and consumption of power; therefore, a conveni</p><p>　　The

7、 development of the transformation and ac transmission by L. Gaulard and J.D. Gibbs of Paris, France, led to ac electric power systems. George Westinghouse secured rights to these developments in the United States. In 18

8、86, William Stanley, an associate of Westinghouse, developed and tested a commercially practical transformer and ac distribution system for 150 lamps at Great Barrington, Massachusetts. In 1889, the first ac transmission

9、 line in North America was put into operation in Oregon b</p><p>　　With the development of polyphase systems by Nikolas Tesla, the ac system became even more attractive. By 1888, Tesla held several patents o

10、n ac motors, generators, transformers, and transmission systems. Westinghouse bought the patents to these early inventions, and they formed the basis of the present-day ac systems.</p><p>　　In the 1890s, the

11、re was considerable controversy over whether the electric utility industry should be standardized on dc or ac. There were passionate arguments between Edison, who advocated dc, and Westinghouse, who favored ac. By the tu

12、rn of the century, the ac system had won out over the dc system for the following reasons;</p><p>　　Voltage levels can be easily transformed in ac systems, thus providing the flexibility for use of different

13、 voltages for generation, transmission, and consumption.</p><p>　　AC generators are much simpler than dc generators.</p><p>　　AC motors are much simpler and cheaper than dc motors.</p>&l

14、t;p>　　The first three-phase line in North America went into operation in 1893-a 2,300 V, 12 km line in southern California. Around this time, ac was chosen at Niagara Falls because dc was not practical for transmittin

15、g power to Buffalo, about 30 km away. This decision ended the ac versus dc controversy and established victory for the ac system.</p><p>　　In the early period of ac power transmission, frequency was not stan

16、dardized. Many different frequencies were in use: 25, 50, 60, 125, and 133 Hz. This posed a problem for interconnection. Eventually 60 Hz was adopted as standard in North America, although many other countries use 50 Hz.

17、</p><p>　　The increasing need for transmitting larger amounts of power over longer distances created an incentive to use progressively higher voltage levels. The early ac systems used 12,44, and 60 kV(RMS li

18、ne-to-line).This rose to 165 kV in 1922,220 kV in 1923,287 kV in 1935,330 kV in 1953,and 765 kV was introduced in the United States in 1969.</p><p>　　To avoid the proliferation of an unlimited number of volt

19、ages, the industry has standardized voltage levels. The standards are 115, 138, 161, and 230 kV for the high voltage (HV) class, and 345, 500 and 765 kV for the extra-high voltage (EHV) class.</p><p>　　With

20、the development of mercury arc valves in the early 1950s, high voltage dc (HVDC) transmission systems became economical in special situations. The HVDC transmission is attractive for transmission of large blocks of power

21、 over long distances. The cross-over point beyond which dc transmission may become a competitive to ac transmission is around 500 kV for around 500 km for overhead lines and 50 km for underground or submarine cables. HDV

22、C transmission also provides an asynchronous link betwe</p><p>　　With the advent of thyristor valve converters, HVDC transmission became even more attractive. The first application of an HVDC system using th

23、yristor values was at Eel River in 1972-a back-to-back scheme providing an asynchronous tie between the power systems of Quebec and New Brunswick. With the cost and size of conversion equipment decreasing and its reliabi

24、lity increasing, there has been a steady increase in the use of HVDC transmission.</p><p>　　Interconnection of neighboring utilities usually leads to improved security results from the mutual emergency assis

25、tance that the utilities can provide. Improved economy results from the need for less generating reserve capacity in each system. In addition, the interconnection permits the utilities to make economy transfers and thus

26、take advantage of the most economical sources of power. These benefits have been recognized from the beginning and interconnections continue to grow. Almost all the </p><p>　　STRUCTURE OF THE POWER SYSTEM<

27、;/p><p>　　Electric power system varies in size and structural components. However, they all have the same basic characteristics:</p><p>　　Are comprised of three-phase ac systems operating essential

28、ly at constant voltage. Generation and transmission facilities use three-phase equipment. Industrial loads are invariably three-phase; single-phase residential and commercial loads are distributed equally among the phase

29、s so as to effectively form a balanced three-phase system.</p><p>　　Use synchronous machines for electricity. Prime movers convent the primary sources of energy (fossil, nuclear, and hydraulic) to mechanical

30、 energy that is, in turn, converted to electrical energy by synchronous generators.</p><p>　　Transmit power over significant distances to consumers spread over a wide area. This requires a transmission syste

31、m comprising subsystems operating at different voltage levels.</p><p>　　Electric power is produced at generating stations (GS) and transmitted to consumers through a complex network of individual components,

32、 including transmission lines, transformers, and switching devices.</p><p>　　It is common practice to classify the transmission network into the following subsystems:</p><p>　　Transmission syste

33、m</p><p>　　Subtransmission system</p><p>　　Distribution system</p><p>　　The transmission system interconnects all major generating stations and main load canters in the system. It f

34、orms the backbone of the integrated power system and operates at the highest voltage levels (typically, 230kV and above).The generator voltage are usually in the range of 11 to 35 kV. These are stepped up to the transmis

35、sion voltage levels, and power is transmitted to transmission substations where the voltage are stepped down to the subtransmission level (typically, 69 kV to 138 kV).The </p><p>　　The subtransmission system

36、 transmits power in smaller quantities from the transmission substations to the distribution substations. Large industrial customers are commonly supplied directly from the substransmission system. In some systems, there

37、 is no clear demarcation between substransmission and transmission circuits. As the system expands and higher voltage levels become necessary for transmission, the older transmission lines are often relegated to subtrans

38、mission function.</p><p>　　The distribution system represents the final stage in the transfer of power to the individual customers. The primary distribution voltage is typically between 4.0 kV and 34.5 kV. S

39、mall industrial customers are supplied by primary feeders at this voltage level. The secondary distribution feeders are supply residential and commercial customers at 120/240V.</p><p><b>　　翻譯：</b>

40、;</p><p><b>　　電力系統(tǒng)的演化</b></p><p>　　商業(yè)用電始于19世紀70年代后期，弧燈用于燈塔照明和街道照明。</p><p>　　第一個完整的電力系統(tǒng)（由發(fā)電機、電纜、熔絲、電表和負荷組成）是由Thomas Edison在紐約城的Pearl Street Station建成并與1882年9月投入運行，這是一個由蒸汽

41、發(fā)動機驅動供給1.5公里內59個用戶組成的直流輸電系統(tǒng)。負荷是包括白熾燈在內的110V供電的電纜系統(tǒng)。幾年之內類似系統(tǒng)在運行在全世界大多數(shù)大城市中。隨著1884年弗蘭克電機的發(fā)展,電機負載計入電力系統(tǒng)系統(tǒng)。這是電力發(fā)展為世界最大產(chǎn)業(yè)之一的開始。</p><p>　　盡管最初廣泛使用直流系統(tǒng)，（但后來）幾乎完全交流系統(tǒng)所取代。到1886年，直流系統(tǒng)的局限性日益突現(xiàn)，只能在很短的距離內從發(fā)電機向外送電。為了保持功率損

42、耗和電壓降落在可接受水平，需提高電壓水平以保證遠距離輸電。發(fā)電機和用電設備不能承受較高電壓電能，因此，方便轉換電壓成為一種必要。</p><p>　　由于L.Gaulard和法國巴黎的J.D.Gibbs開發(fā)了變壓器和交流輸電技術，由此產(chǎn)生了交流電力系統(tǒng)。George Westinghouse獲得了這些新權利在美國應用的權利。在1886年，西屋的助手William Stanley開發(fā)和試驗了商業(yè)實用的變壓器和在Gr

43、eat Brrington，Massachusetts的由150個電燈組成的交流配電系統(tǒng)。在1889年,第一個交流輸電線路在北美Oregon 的Willamette Falls 和 Portland之間投運。這是一個單相線傳輸電能為4000 V輸送距離超過21公里的電力系統(tǒng)。</p><p>　　隨著Nikolas Tesla多相系統(tǒng)的建立和發(fā)展，交流系統(tǒng)變得更加有吸引力。到1888年，Tesla持有關于交流電動

44、機、發(fā)電機、變壓器和輸電系統(tǒng)的若干專利。Westinghouse購買了這些早期發(fā)明專利，這些發(fā)明奠定了當今交流電力系統(tǒng)的基礎。</p><p>　　在19世紀90年代,關于電力工業(yè)應采用直流還是交流作為標準的相當大的爭論。在主張直流的Edison和偏好交流的Westinghouse之間發(fā)生過激烈的辯論。到世紀末,交流系統(tǒng)戰(zhàn)勝了直流系統(tǒng),原因如下：</p><p>　　在交流系統(tǒng)中容易變壓，

45、因此可以靈活地使用不同電壓等級的發(fā)電機，變壓器和用電設備。</p><p>　　交流發(fā)電機比直流發(fā)電機簡單得多。</p><p>　　交流電動機比直流發(fā)電機更簡單，更便宜。 </p><p>　　第一個三相12公里2300V輸電線路在于1893年在北美 California南部投運。在那個時候，因為直流不能實際傳輸電能到30公里外的Buffalo，所以Niagara

46、 Falls選擇了直流供電。這個決定結束了交流和直流爭議,奠定了交流系統(tǒng)成功的基礎。 </p><p>　　在早期的交流輸電中頻率不統(tǒng)一。 使用許多不同平頻率為：25、50、60 、125和133赫茲。這是互聯(lián)的一個問題。北美最終采用60HZ為標準，盡管其他地區(qū)和國家采用50HZ。</p><p>　　由于大量長距離輸電的增長需要，創(chuàng)造和激勵了電壓水平的逐漸提高。 早期的交流系統(tǒng)使用12、

47、44和60kV（RMS line-to-line）。電壓等級在1922年上升到165kV，1923年上升到287kV，1953年上升到330kV，1969年美國引進了765kV的高壓。</p><p>　　為了避免電壓等級的無限增加，電力行業(yè)將電壓等級標準化。這些高壓類（HV）的標準電壓等級是：115、138、161和230 kV，特高壓（EHV）有345、500和765kV幾個電壓等級 。 </p>

48、;<p>　　隨著20世紀50年代初汞弧閥發(fā)展，高電壓直流傳輸系統(tǒng)變得經(jīng)濟。為此，高壓直流輸電在大面積、長距離方面很具有吸引力。在500kV500公里的架空線路和50公里的地下電纜或者海底電纜輸電中，直流輸電比交流輸電在跨接方面具有很大的競爭優(yōu)勢。高壓直流輸電也支持在因為考慮系統(tǒng)穩(wěn)定性或者不同頻率之間不能世紀聯(lián)絡的系實現(xiàn)異步互聯(lián)。在1954年，第一個現(xiàn)代的商業(yè)用高壓直流輸電是通過96公里海底電纜在瑞典大陸和Gotland島

49、之間實現(xiàn)互聯(lián)。</p><p>　　隨著晶閘管閥轉換器出現(xiàn)、高壓直流輸電變得更有吸引力。1972年Eel河提供連續(xù)方案申請直流輸電使用半導體晶閘管，方案提供了Quebec系統(tǒng)和New Brunswick系統(tǒng)之間的異步互聯(lián)。隨著轉化設備的成本降低、體積變小和可靠性的提高，高壓直流輸電的使用實現(xiàn)了穩(wěn)定增長。</p><p>　　相鄰的公用電網(wǎng)互聯(lián)一般可以緩解不同系統(tǒng)間彼此緊急情況而帶來的安全性

50、問題。減少每個系統(tǒng)中的備用容量可以使整個方案更經(jīng)濟。另外，互聯(lián)可以使公用電網(wǎng)變電更具經(jīng)濟性，因此可以實現(xiàn)能源的優(yōu)化配置。一開始這些利益就得到肯定，系統(tǒng)互聯(lián)也得到推廣。幾乎所有的美國和加拿大現(xiàn)在的公用電網(wǎng)都是一個系統(tǒng)及其復雜的一部分。如此這樣一個系統(tǒng)的設計和安全穩(wěn)定運行的確是一個挑戰(zhàn)性的問題。</p><p><b>　　電力系統(tǒng)的結構</b></p><p>　　電力

51、系統(tǒng)在規(guī)模和結構都有變化，但他們都有著相同的基本特征。</p><p>　　主要包括三相交流系統(tǒng)的穩(wěn)定工作電壓，發(fā)、輸電設施使用三相設備。工業(yè)負載總是三相；單相的居民用電和商業(yè)用電在同一時期總是分散平衡的，從而有效地形成一個平衡的三相系統(tǒng)。</p><p>　　使用同步發(fā)電機發(fā)電。原動機將原始能量（化石燃料，核能，液壓）轉化為機械能，同步發(fā)電機再將機械能轉化為電能。</p>

52、<p>　　電力傳輸較大距離供大面積負荷時，這樣的系統(tǒng)需要包含不同電壓等級的子系統(tǒng)。</p><p>　　電力產(chǎn)生于發(fā)電廠（GS），通過使用一系列獨特的電網(wǎng)設備包括輸電線路，變壓器，開關設備構成的復雜網(wǎng)絡傳輸給用戶。 </p><p>　　輸電網(wǎng)絡習慣分為以下幾種子系統(tǒng)：</p><p><b>　　1.輸電系統(tǒng)</b></p

53、><p><b>　　2.二次系統(tǒng)</b></p><p><b>　　3.配電系統(tǒng)</b></p><p>　　輸電系統(tǒng)互聯(lián)著系統(tǒng)中所有的主要發(fā)電機和主要負荷中心。它構成了整個電力系統(tǒng)的主網(wǎng)架并運行在最高電壓水（通常230kV及以上）。發(fā)電器電壓通常是在11到35 kV范圍內。這些將電壓升壓到輸電網(wǎng)的電壓水平，電能傳輸?shù)诫妷?/p>

54、水平較低的(通常是69千伏到138千伏)降壓變電站。產(chǎn)生和傳輸電能的系統(tǒng)通常被稱為大容量電力系統(tǒng)。 </p><p>　　在輸電系統(tǒng)中，一部分電能從輸電變電站傳輸?shù)脚潆娮冸娬?。工業(yè)大負荷一般都直接由輸電變電站供電。在某些系統(tǒng)中，二次輸電網(wǎng)和輸電線路沒有明確的劃分。隨著系統(tǒng)的擴展和更高電壓等級輸電成為必要，老輸電線路往往實現(xiàn)二次輸電網(wǎng)的功能。配電系統(tǒng)代表著電能供給個人用戶的最后階段。初次分配的電壓一般在4.0千伏