電機外文翻譯---火電大機組勵磁系統(tǒng)的回頤與展望

1、<p><b>　　附錄</b></p><p>　　附錄一 外文資料原文及翻譯</p><p><b>　　A1.1原文</b></p><p>　　Retrospect and Prospect of Excitation Systems of Large Size Turbogenerators</p

2、><p>　　From ELECTRICITY 2002 NO.4</p><p>　　By Du xingyou</p><p>　　Member of Scientific and Technological</p><p><b>　　都興有</b></p><p>　　國家電力公司科學技術委員

3、會委員</p><p>　　[Abstract] This paper briefs the developmental course,manufacturing and applications,as well as future prospect of excitation systems of large size turbogenerators in China,emphatically expounds

4、 the advantages of self-excitation systems with potential source rectifiers and matters needing to be noted during dissemination and application of them .</p><p>　　[Keywords] thermal power plant;large size t

5、urbogenerator;excitation system;self-shunt excitation </p><p>　　In the late 1970s,the perfection works of indigenous large size thermal power generating units were started,the main objects of perfection were

6、 the original 125 MW,200 MW and 300 MW generating units,the excitation systems of these units,except for a few units which employed direct current (d.c) exciters,were mainly equipped with excites,which included excitatio

7、n power source(permanent magnet machine,alternating current(a.c.) rotating exciter, rectifier cubicle),slip ring, brush, brush holder, as</p><p>　　1.1 Harbin Electric Machinery Works Ltd.Co</p><p&

8、gt;　　All the original 200 MW generators employed exciters; the imported type 300 MW generators were equipped with exciters in the initial stages, and could be equipped with self-shunt　excitation system later; the importe

9、d type 600 MW generators　were first equipped with brushless excitation, and can also be　equipped with self-shunt excitation system now too. Since these　three excitation systems are available, it is very convenient for　cu

10、stomers to choose any kind excitation system to equip the　recentl</p><p>　　1.2 Shanghai Electric MachineryWorks Ltd. Co.</p><p>　　Both the original double water inner cooling 125 MW (135 MWnow)

11、and 300 MW generators were equipped with exctlers; the imported type 300 MW and 600 MW generators were equippedwith brushless excitation　originally, and can be equipped with　self-shunt excitation system now. Hence three

12、types of excitation　systems are available.</p><p>　　1.3 Dongfang Electric Machinery Ltd. Co.</p><p>　　All the original 200 MW generators were equipped with　exciters, the 300 MW generators were e

13、quipped with exciters　or self-shunt excitation system; the 600 MW generators with　Japanese Hitachi technology introduced employ self-shunt　excitation system. The 125 (135) MW generators made　recently can be equipped with

14、 exciters and self-shunt　excitation system.</p><p>　　1.4 Beljing Turbogenerator Ltd. Co.</p><p>　　The original 200 MW generators also employ exciters; the 330　MW generators jointly produced with

15、 France based Alsthom　Corp. are equipped with brushless excitation system, the　domestication scheme of generators has passed the appraisal　and examination, viewing from marketing, serf-shunt excitation　can be provided as

16、 well.</p><p>　　2.1 Material quality etc. problems of slip ring</p><p>　　Material quality of slip ring, ventilation, carbon powder, brush　holder and its constant pressure spring etc. problems wo

17、rried　about in the past have all been solved. Now all slip rings can be　made with outer diameter not exceeding 400 mm and linear　speed not more than 70 m/s; the constant pressure spring　needed for brush holder has been s

18、olved and can be plugged　in and pulled out safely and conveniently during operation; the　quality of brushes can satisfy the requirements, but some</p><p>　　generators were completed with imported parts.</

19、p><p>　　2.2 Selection and use of exciters and brushlese exchationsystem</p><p>　　As a result of raising component quality of indigenous rectifiers and improving reliability of a.c. exciters and per

20、manent-magnet machines, both exciters and brushless excitation system may basically be selected and used in parallel.</p><p>　　2.3 De.excitation switch</p><p>　　Poor arc suppression performance

21、of breaks and ineffectiveness　of mechanism etc. problems existed with the old generation de-excitation switches. While certain debugging experiences were　gained at home and manufacturing technologies were imported　later,

22、 de-excitation switches yet couldn't be spread and applied　throughout the country. Consequently most of 300 MW and 600　MW generators still employ the imported d.c. de-excitation　switches when selecting and using self

23、-shunt excitation system.</p><p>　　The imported type 300 MW and 600 MW generators employed　brushless excitation without de-excitation switches in the early　stage. The original de-excitation switches in excit

24、er system of　125 MW and 300 MW double water inner cooling generators　were ever short-circuited in Shandong and this experience　passed appraisal. But when employing exciter scheme and serf-shunt excitation system, the d.c

25、. de-excitation switches are still finalized to equip in the design, for time would be delayed without the s</p><p>　　Hebei Province had some experiences in employing "Hebei SKM-2O0 automatic de-excitat

26、ion and slip over-voltage protection device" in exciter system of 200 MW generators and installing de-excitation switches on a.c. side, and these experiences passed appraisal.The 660 MW generators imported from Ger

27、many based Siemens Corp. in Hebei Hanfeng Power Plant employ inverters and de-excitation switches on a.c. side. It is reported that they have been running normally up to now. As for the de-excitation r</p><p&g

28、t;　　2.4 Brushless excitation</p><p>　　Since the brushless excitation technology was introduced to China, the former ministries of Machinery Building and Water Resources & Electric Power placed the comple

29、ted condensers and fusible cut-outs as the key research subjects, which were successfully tested and appraised on the 300 MW generators in Shanghai Wujing Power Plant, but the domestically-mede completed products were no

30、t formed, sothey still rely on imports. As for the components of thyristors, used in both brushless excitation and </p><p>　　were simply laid out, were used for 600 MW supercritical pressure turbogenerators

31、of ABB Corp. in Shanghai Shidongkou No.2 Power Plant.</p><p><b>　　2.5 AVR</b></p><p>　　In the past, neither the AVRs completed by indigenous manufacturers nor the AVRs completed with

32、 imported technologies for 300 MW and 600 MW generators were advanced. The extreme sample was the runaway accident of 200 MW generating unit in Shanxi Datong Power Plant. It was found through investigation that the unit

33、was starting to connect to the power network at that time. When the load rose to 170 MW, the AVR failed to follow to regulate, resulting in fall-out of synchronism, which induced instab</p><p>　　The afore me

34、ntioned AVRs may be applied to the various size　generators and three kinds of excitation systems (exciters,　brushless excitation and self-shunt excitation). Exciters and　brushless excitation belong to rotating excitation

35、 system, hence　all are completed by turbogenerator manufacturers. If self-shunt　excitation system is employed, then except slip rings, brushes　and brush holders which will be supplied accordingly by　generator manufacture

36、rs, excitation systems may find more　alternative</p><p>　　jointly produced) in Shandong Zouxian Power Plant were　provided by ABB Corp., some indigenous 300 MW turbogenerators selected ABB”s products and some

37、 indigenous 300 MW turbogenerators selected US based Roles Royals Crop”s products.</p><p>　　2.6 Background of developing self-shunt excitation system </p><p>　　In the past all the large size the

38、rmal power generating units employed exciters, since the manufacturing technologies of WH”s 300 MW and 600 MW generating units were introduced, China began to produce brushless exciation systems. They have been operating

39、 smoothly with little maintenance up to now, but both these two excitation schemes employ rotating exciter in which rotating part is the key part needing attention and regular maintenance as compared with self-shunt exci

40、tation system.</p><p>　　China EPRI,alter investigating, put forward the report Feasibility Analyses of Adopting Self-excitation System for Large Size Turbogenerator. Though studying the impacts of self-shunt

41、 excitation system on transient phasor and transient voltage stability of small grid with large generating units and large grid system, as well as the impacts of self-shunt excitation system on relay protection, they con

42、cluded that, "it is feasible to disseminate and apply serf-shunt excitation system in large size </p><p>　　(1) The reliability of self-shunt excitation system is high, since there isn't rotating par

43、t in it;</p><p>　　(2) Considering the stability requirement of transient phasor, it is feasible to disseminate and apply self-shunt excitation system in large size turbogenerators. When the high voltage exit

44、s of rare generators employing self-shunt excitation system are three-phase short-circuited, at lower ceiling voltage ratio of field-focing (K=2) in calculation, corresponding to 1.6 times of that using　international cal

45、culation method), the stability level of transient　phasor is basically the same in comparis</p><p>　　excitation system with 0.35 sec. of time constant. With the ceiling　voltage ratio of field forcing raised,

46、 the advantages of self-shunt　excitation system will become more obvious.</p><p>　　(3) Viewing from the transient voltage stability requirement of　power system, it is feasible too to disseminate and apply se

47、lf-shunt excitation in large size turbogenerators, which may not　only keep the transient voltage stability level of power system,but also raise the transient voltage stability level of power system,even may make the inst

48、able transient voltage of power system　to become stable under some conditions.</p><p>　　(4) Applying self-shunt excitation system in large size　turbogenerators, not only won't influence the reliable oper

49、ation　of main relay protection, and can ensure correct operation of　backup protection and clear of fault.</p><p>　　(5) Since there isn't coaxial rotating exciter in the generator with　self-shunt excitati

50、on system, the torsional vibration mode of　turbogenerator is reduced, thus decreasing the possibility of　shaft system damage resulting from torsional vibration.</p><p>　　(6) The selection of parameters of se

51、lf-shunt excitation system　is more flexible than that of conventional excitation system, the　requirements may be raised in light of the features of different　power networks.</p><p>　　It should be indicated t

52、hat, the dissemination and application of　serf-shunt excitation sysem in large size turbogenerators　in China　ever underwent a considerable endless route, from feeling　worried about the self-shunt excitation system, thru

53、technical　studying and discussing, importing (such as importing the　products of Roles Royals and ABB etc. corps.), digesting,　domestication, demonstration, to disseminating and applying　etc. courses. Currently, almost al

54、l the 300 MW unit projects have　adop</p><p>　　It should be explained additionally that, when the self-shunt　excitation system is adopted, since the shaft system is　shortened, the 300 MW turbogenrator set may

55、 be arranged　transversely with the front part of steam turbine directed at boiler　house, thus the piping system etc. equipment will be laid out　more conveniently, and the costs of civil works and equipment　installation w

56、ill thus be reduced. Some turbogenerator sets are　even arranged obliquely with front of steam turbine directed at　boile</p><p>　　In addition, it is not proper to regard the excitation system only　as an appur

57、tenance of generator, which is closely bound up with the power system. For example, all the modem AVRs are equipped with power system stabilizers (PSS) and the excitation system may be purchased by way of competitive bid

58、ding independently. The excitation systems of old turbogenerators may be retrofitted by using self-shunt excitation. The retrofitting and application experiencas at home and abroad show that, no adverse</p><p&

59、gt;　　(1) The 600 MW and above, even 1000 MW class large thermal power generating units, as well as nuclear power generating units will be more developed in the future, if the direct current switches are continuously empl

60、oyed for the required excitation switches in self-shunt excitation systems, more difficulties will be encountered in the selection of products. In accordance with experience of adopting inversion plus de-excitation switc

61、h on a.c. side at home and abroad (such as the retrofitting of 20</p><p>　　(2) PSS should be debugged and put into operation for improving the reliability of power network operation.</p><p>　　(3

62、) The following issues should be attached importance in calls for bid:</p><p>　　1) Not only the rated output (power), but also the rated capacity (MVA) of generators should be clarified. In order to take off

63、 the required power and capacity of self-shunt excitation system, the layout of metering system should be well concerted.</p><p>　　2) Since the power source of self-shunt excitation system is connected to th

64、e outlet of generator, thermal stability is not the main concern, but mechanical stability should be attached much importance.</p><p>　　3) No matter dry-insulation transformer or oil-immersed transformer is

65、employed, the capacity of transformer should be considered to increase as a result of the influences of harmonics and stray field as well as the field-forcing requirements of yarious working conditions.</p><p&

66、gt;　　4) As for imported type 300 MW and 600 MW turbogenerators, their rated capacities are defined as 353 and 667 MVA according to the past traditional standard, actually there still are "maximum continuous ratings&

67、quot; (according to the practice in USA, this is just rated capacity) 385 (386) and 727 (728) MVA. The capacity of excitation system should be designed and completed based on the latter. This is the difference between th

68、e manufacturing technology of the large size generating units imported from</p><p><b>　　A1.2譯文</b></p><p>　　火電大機組勵磁系統(tǒng)的回頤與展望</p><p>　　譯自<< ELECTRICITY 2002 NO.4>

69、></p><p><b>　　都興有</b></p><p>　　國家電力公司科學技術委員會委員</p><p>　　摘要:介紹中國大型起輪發(fā)電機勵磁系統(tǒng)的發(fā)展歷程、制造和應用情況及其發(fā)展前景，特別著重論述自并激勵磁系統(tǒng)的有點及推廣應用時需注意的問題。</p><p>　　關鍵詞:火力發(fā)電廠;大型氣輪發(fā)電機;勵磁

70、系統(tǒng);自并激勵磁</p><p>　　20世紀70年代末，原電力部設置了大機組辦公室，著手國產(chǎn)大機組主輔設備的完善工作，后與原一機部進行了300,600 M W 級機組制造技術的引進事宜。當時定義的火電大機組是指容量為100 M W及以上的機組，實際上國產(chǎn)大機組完善化的主要對象是原125,200,300 M W 機組。其勵磁系統(tǒng)除少數(shù)機組用直流勵磁機外，主要是用三機勵磁配套，包括勵磁電源(永磁機、交流旋轉勵磁機、

71、整流柜)、滑環(huán)、電刷、刷握及滅磁開關、滅磁電阻、AVR。 20世紀80年代未，300 ,600 M W 機組引進美國西屋與燃燒公司的制造技術，西屋公司轉讓的勵磁系統(tǒng)技術是無刷勵磁。到20世紀90年代末，則多選用自并勵勵磁系統(tǒng)。</p><p>　　1.1 哈爾濱電機廠</p><p>　　原200 M W 發(fā)電機均采用三機勵磁;引進型300MW 發(fā)電機先是配三機勵磁，后來也能配自井勵勵磁;

72、引進型600 M W 發(fā)電機先是配無刷勵磁，現(xiàn)在也開始能配自井勵勵磁。3種方式都具備。近年生產(chǎn)的125 MW(135,200MW)發(fā)電機勵磁系統(tǒng)配套選擇就更方便用戶。</p><p><b>　　1.2 上海電機廠</b></p><p>　　原雙水內冷125 MW(現(xiàn)為135 M W)與300 M W發(fā)電機均系配三機勵磁;引進型300 ,600 MW 發(fā)電機先是配無

73、刷勵磁，現(xiàn)在也能配自并勵勵磁。因此， 3種勵磁方式都有。</p><p><b>　　1.3 東方電機廠</b></p><p>　　原200 M W 發(fā)電機均采用三機勵磁;300 M W 發(fā)電機有三機勵磁和自并勵勵磁2種;引進日本日立公司技術的600 M W 發(fā)電機采用自并勵勵磁系統(tǒng)，近年生產(chǎn)的125 MW(135 MW)發(fā)電機勵磁系統(tǒng)能配三機勵磁和自并勵勵磁2種方

74、式。</p><p>　　1.4 北京重型電機廠</p><p>　　原200 M W 發(fā)電機也是采用三機勵磁; 與法國原阿爾斯通公司合作生產(chǎn)的330 M W 發(fā)電機配無刷勵磁系統(tǒng)，發(fā)電機國產(chǎn)化方案已評審通過，從市場看，也能配自并勵勵磁。</p><p>　　2 勵磁系統(tǒng)的發(fā)展情況</p><p>　　2.1 滑環(huán)材質等問題</p>

75、;<p>　　過去擔心的滑環(huán)材質、通風、碳粉、刷握及其恒壓彈簧等問題均已解決，現(xiàn)在滑環(huán)都能做到外徑不大于400mm,使線速度不超過70 m/s;刷握所需的恒壓彈簧問題也已解決，而且運行中能做到插拔安全方便;碳刷質量也能達到要求，但有的廠配用進口件。</p><p>　　2.2 三機勵磁系統(tǒng)與無刷勵磁系統(tǒng)的選用</p><p>　　由于國產(chǎn)整流元器件質量的提高及交流勵磁機、永磁

76、機的可靠性的提高，使三機勵磁系統(tǒng)與無刷勵磁系統(tǒng)基本可并列選用。</p><p><b>　　2.3 滅磁開關</b></p><p>　　過去老一代的滅磁開關存在斷口滅弧性能差、機構不靈等問題，原東北技改局雖有相當?shù)恼{試經(jīng)驗。但沒有在全國推廣使用。其后雖引進了制造技術，但產(chǎn)品未能完全占領市場。所以，300,600 MW發(fā)電機在選用自并勵勵磁系統(tǒng)時，仍多采用進口直流開關

77、。</p><p>　　引進型300,600 M W 發(fā)電機前期用的是無刷勵磁，沒有，也不設滅磁開關。山東曾在125,300 MW雙水內冷發(fā)電機的三機勵磁系統(tǒng)中，將原滅磁開關短路運行過，還做過鑒定，但在采用三機勵磁方式與自并勵勵磁方式時.仍定型裝設直流滅磁開關，理由是擔心若無開關會托延時問， 當發(fā)電機本身故障時擴大燒損范圍。</p><p>　　河北對200 M W 發(fā)電機三機勵磁系統(tǒng)采用

78、逆變和在交流側裝設開關滅磁有經(jīng)驗，也做過鑒定。邯峰電廠從德國西門子公司進口的660MW 發(fā)電機就是采用逆變和在交流側加開關滅磁的方式，迄今運行正常。至于滅磁電阻，多采用國產(chǎn)氧化鋅件，ABB公司則多配用碳化硅。</p><p><b>　　2.4 無刷勵磁</b></p><p>　　自從引進無刷勵磁技術后，原機械、水電兩部將配套的電容器、熔斷器列人了攻關課題，在吳涇電

79、廠300 M W 發(fā)電機上試驗成功并進行過鑒定，但沒有形成國產(chǎn)配套，仍依靠進口。至于可控硅元器件無論是無刷勵磁或自并勵勵磁，迄今仍多選用進口件。自并勵勵磁系統(tǒng)的電源變壓器，國內多選用干式。由于我國已有多家企業(yè)引進制造技術， 所以國產(chǎn)干式變壓器是被選用的基本模式。石洞口二廠進口的ABB公司600 M W 超臨界機組采用的是油浸式變壓器，布置也很簡單。2.5 AVR</p><p>　　過去制造廠配套的AVR水平都不

80、高， 即使是300,600 M W 用引進技術配套的AVR，也并不先進。特別是大同電廠200 M W 機組飛車事件，在調查中發(fā)現(xiàn)該機組當時啟動并網(wǎng)、負荷升到170 M W 時，由于AVR不能跟蹤調節(jié)以致失步，誘發(fā)機組原存在的軸系不穩(wěn)定，導致毀滅性事故。經(jīng)電科院研究后證明.此系事故起因。隨后，由電科院列專題研究開發(fā)了微機型AVR，并將技術轉讓予南京自動化設備廠生產(chǎn)。</p><p>　　以上所述的AVR 可用于各種

81、容量發(fā)電機及三機勵磁、無刷勵磁和自并勵勵磁等3種勵磁系統(tǒng)中。三機勵磁和無刷勵磁屬于旋轉勵磁機系統(tǒng)，勵磁系統(tǒng)均由發(fā)電機制造廠成套。如果采用自并勵勵磁系統(tǒng)，除了滑環(huán)、碳刷、刷握由發(fā)電機制造廠負責配供外，勵磁系統(tǒng)可選擇的供貨單位就更多，國內已有先例，進口機組也有先例，如山東鄒縣電廠2臺口立-東方合作型600 M W 發(fā)電機的自并勵勵磁系統(tǒng)就是采用ABB公司的。國產(chǎn)300 M W 發(fā)電機有選用ABB公司的，還肩選用美國R-R公司的。發(fā)展至今的A

82、VR已非“國產(chǎn)的自并激靜止勵磁系統(tǒng)尚外于工業(yè)性試驗”，在這一點上，水電機組走在火電機組的前面，值得學習。</p><p>　　2.6 關于開發(fā)自并勵勵磁系統(tǒng)的背景</p><p>　　過去火電大機組都使用三機勵磁系統(tǒng)，引進西屋公司300,600 M W 機組制造技術后，就有了無刷勵磁系統(tǒng)，迄今運行情況良好，維護工作量也不多，但這2種勵磁方式都是采用旋轉勵磁機，相對于自并勵靜止勵磁系統(tǒng)而言，

83、轉動部件是關鍵。</p><p>　　原水電部電科院在對自并勵勵磁系統(tǒng)進行研究后提出《大型汽輪發(fā)電機采用自勵勵磁系統(tǒng)的可行性分析》報告。通過大機小網(wǎng)和大網(wǎng)系統(tǒng)暫態(tài)功角穩(wěn)定影響及自并勵勵磁方式對繼電保護的影響的研究后得出結論，認為“我國電網(wǎng)大型汽輪發(fā)電機推廣采用自并勵勵磁系統(tǒng)是可行的：</p><p>　　(1 )自并勵勵磁系統(tǒng)由于沒有旋轉部件，運行可靠性高。</p><

84、p>　　(2)從暫態(tài)功角穩(wěn)定要求考慮，大型汽輪發(fā)電機推廣采用自并勵勵磁系統(tǒng)是可行的。個別發(fā)電機采用自并勵勵磁系統(tǒng)時，高壓出口三相短路，在較低強勵倍數(shù)下(計算中為K=2倍，相當于國標計算方法的1.6倍)，暫態(tài)功角穩(wěn)定水平與時間常數(shù)為0.35 s 的常規(guī)勵磁系統(tǒng)相比，基本相同。而全網(wǎng)機組均采用自并勵勵磁系統(tǒng)時，在低強勵倍數(shù)下，暫態(tài)功角穩(wěn)定水平優(yōu)于全網(wǎng)機組均采用0.35s的常規(guī)勵磁系統(tǒng)。強勵倍數(shù)提高后，自并勵系統(tǒng)的優(yōu)勢更加明顯。<

85、/p><p>　?。?）從電力系統(tǒng)暫態(tài)電壓穩(wěn)定要求出發(fā)， 大型汽輪發(fā)電機推廣采用自并勵系統(tǒng)也是可行的。它不會降低系統(tǒng)的暫態(tài)電壓穩(wěn)定水平，而且可提高系統(tǒng)的暫態(tài)電壓穩(wěn)定水平，甚至可使在某些條件下暫態(tài)電壓不穩(wěn)定的系統(tǒng)為穩(wěn)定</p><p>　　(4)大型汽輪發(fā)電機采用自并勵系統(tǒng)，不會影響主保護的可靠動作，也可保證后備保護正確動作，切除故障。</p><p>　　(5)自并勵勵

86、磁發(fā)電機沒有同軸旋轉的勵磁機，減少了機組的扭振模式， 降低了軸系扭振損壞的可能性。</p><p>　　(6)自并勵勵磁系統(tǒng)參數(shù)的選擇比常規(guī)勵磁系統(tǒng)更為靈活，可根據(jù)不同電網(wǎng)的特點提出要求，以滿足其需要”</p><p>　　自并勵靜止勵磁系統(tǒng)應用于水電系統(tǒng)似乎“理所當然、別無選擇”，已有豐富的經(jīng)驗，但要推廣采用到大型汽輪發(fā)電機上卻經(jīng)歷了相當漫長的道路。原先東方電機廠開發(fā)并推薦在寶雞電廠30

87、0MW 發(fā)電機上使用，但因當時擔心寶雞電廠地處陜西電網(wǎng)震蕩中心而作罷。隨著管理體制改革，由計劃經(jīng)濟轉向市場經(jīng)濟，在原電力部科技司主持下，由華北電管局支持，在北京召開了自并勵靜止勵磁的技術研討會，會上建議推廣該技術，可以先進口，如Roles Royals公司和ABB公司的產(chǎn)品。以此為契機， 一批300 M W機組工程項目幾乎都采用了自并勵靜止勵磁系統(tǒng)，而且2001年以來新的600 M W 機組工程項目。如定曲、嘉興、臺山電廠，也都選用了自

88、并勵靜止勵磁系統(tǒng)。</p><p>　　在原電力部的自并勵勵磁系統(tǒng)技術研討會后，相當一批工程項目均采用自并激勵磁系統(tǒng)， 當時的客觀條件是還沒有國產(chǎn)化的成熟產(chǎn)品，采用進口自并勵靜止勵磁系統(tǒng)的價格與國產(chǎn)旋轉勵磁機無刷勵磁系統(tǒng)持平。如果利用靜止勵磁系統(tǒng)，由于軸系縮短， 300 M W 機組若在主廠房內能改為橫向布置，機頭直對鍋爐房，則管道等布置將更方便，從而節(jié)省土建、安裝費用。國外甚至有將機頭對鍋爐、軸系橫向偏斜、以縮

89、短主廠房跨度的布置實例。</p><p>　　此外，勵磁系統(tǒng)在大機組、大電網(wǎng)中已不宜僅視之為發(fā)電機的一個附屬裝置，它與電力系統(tǒng)密切相關，如現(xiàn)代的AVR都配有PSS功能。牡丹江電廠改造后的經(jīng)驗證明，將PSS調試投人運行后，改善了故障后電網(wǎng)低頻振蕩，從而釋放了電廠窩電，達到滿發(fā)，取得了顯著的經(jīng)濟效益。根據(jù)現(xiàn)在的市場情況和貴州省10臺300 M W 機組的招投標經(jīng)驗，已可做到如上述日立600 M W 發(fā)電機勵磁系統(tǒng)的單

90、獨招投標酉己套了。</p><p>　　美國100MW 發(fā)電機的改造都采用了自并勵勵磁系統(tǒng)， 這一點對我國的改造工作頗有參考借鑒價值。實際上，我國已有田家庵等電廠改造的實績。根據(jù)加拿大的經(jīng)驗，迄今尚未發(fā)現(xiàn)電力系統(tǒng)中大量使用自并勵勵磁后對電力系統(tǒng)的負面影響，這是國內近幾年來幾乎新建工程都樂于采用自并勵勵磁系統(tǒng)的原因之一。</p><p><b>　　希望與建議</b>&

91、lt;/p><p>　　今后火電大機組發(fā)電機容量將多發(fā)展600MW 及以上、甚至1 000 M W 級工程，自并勵勵磁系統(tǒng)中所需勵磁開關若繼續(xù)用直流開關，產(chǎn)品選用上將遇到更多困難。根據(jù)河北200 M W 發(fā)電機改造用逆變加交流側開關滅磁的經(jīng)驗， 及邯峰電廠進口西門子公司660 M W 發(fā)電機也用逆變加交流側開關滅磁的經(jīng)驗，最好進行系統(tǒng)總結并作必要的試驗研究，開發(fā)出本地化的成套產(chǎn)品。</p><p&

92、gt;　　(2)要重視勵磁系統(tǒng)既有的特點需要，又與電力系統(tǒng)密切相關，特別是要各方配合，將PSS功能調試投人使用。</p><p>　　(4)根據(jù)參加招投標工作時遇到的情況，下列問題應予注意:</p><p>　　a.發(fā)電機不能只說額定功率，還要明確其額定容量。為了扣除自并勵勵磁系統(tǒng)所需功率與容量后，計量系統(tǒng)布置設計要配合好。</p><p>　　b .由于自并勵勵磁

93、系統(tǒng)的電源接自發(fā)電機出口，熱穩(wěn)定不是主要的問題，而機械穩(wěn)定性應予充分關注。</p><p>　　c.不論是采用干式變壓器或油浸式變壓器，由于諧波與雜散磁場的影響，要考慮加大變壓器的容量。</p><p>　　d.對引進型300,600 M W 發(fā)電機，其額定容量按過去的傳統(tǒng)標準定為353,667 MVA，實際上還有“最大連續(xù)容量”(按美國的做法，這就是額定容量) 358 (386)、727