電氣專(zhuān)業(yè)外文翻譯

1、外文資料翻 譯Reliability of Lightning ResistantOverhead Distribution LinesLighting continues to be themajor causeof outagesonoverheadpower distribution lines. Through laboratory testing and field observationsand measurements, the properties of a lightning stroke andits effects on electrical distribution s

2、ystem componentsare well-understoodphenomena.This paperpresentsa compilation of 32 yearsof historical recordsfor outage causes,duration, and locationsfor eight distribution feedersat the Oak Ridge National Laboratory (ORNL) .Distribution type lightning arresters are placed at dead-endand angle struc

3、tures at pole mounted wormer locations and at high points on the overheadline. Station class lightning arresters are used to protect undergroundcable runs, pad mounted switchgear and unit substation transformers. Resistanceto earth of eachpole ground is typically 15 ohms or less. At higher elevation

4、s in the system, resistance to earth is substantially greater than 15 ohms, especially during the dry summer months. At these high points, ground rods were riven and bonded to the pole grounding systems in the 1960's in an attempt to decreaselightning outages. Theseattempts were only partially s

5、uccessful in lowering the outage rate. From a surge protection standpoint the variety of pole structures used (in-line, corner, angle, dead end, etc.) and the variety of insulators and hardware used does not allow each 13.8 kV overhead line to be categorized with a uniform impulse flashover rating (

6、170 kV, etc.) or a numerical BIL voltage class (95 kV BIL; etc.). For simplicity purposes in the analysis, each overheadline was categorized with a nominal voltage construction class (15 kV, 34 kV, or 69 KV). Six of the eight overhead lines (feeders 1 through 6) were built with typical REA Standardh

7、orizontal wood cross arm construction utilizing single ANSI Class55- 5 porcelain pin insulators (nominal 15 kV insulation). The shield angle of the overhead ground wire to the phase conductors is typically 45 degrees. One overhead line (feeder 7) was built with transmission type wood pole constructi

8、on becausethe line extended to a research facility which was to have generatedelectricalpower to feed back into the grid. Pole structure of this line are of durable wood cross aconstruction which utilize double ANSI 52-3 porcelain suspension insulators to support the conductors (nominal 34 kV insula

9、tion). The shield angle of the overhead ground wire to the phase conductors for feeder 7 is typically 30 degrees. In 1969, an overhead line (feeder 8) was intentionally built with "lightning resistant" construction in an attempt to reduce lightning causedoutages. Pole structures of the lin

10、e have phase over phase 24-inch long fiberglass suspension brackets with double ANSI 52-3 porcelain suspension insulatorsto support the conductors (nominal 69 kV insulation). The shield angle of the overhead ground wire to thephaseconductors for feeder 8 istypically 30 degrees. The failure data was

11、compiled for each of the eight 13.8 kV feeders and is presentedin Table, along with pertinent information regarding feeder construction, elevation, length, and age.A key finding of the failure analysis is that weather-related events account for over half (56%) of the feeder outagesrecorded. Fifty-se

12、ven of the 76 weather-related outageswere attributed to lightning. Insulation breakdown damagedue to lightning is also suspectedin at least a dozen of the equipment failures observed. The data indicates overhead lines which pass over high terrain are less reliable becauseof the greater exposure to l

13、ightning. For example, feeder 3 had the most recorded outages (48), of which two-thirds were due to weather-related events; this feeder is also the highest line on the plant site, rising to an elevation of 450 above the reference valley elevation. Overhead lines that are longer and to which more sub

14、stations and equipment are attached were also observed to be less reliable (more exposure to lightning and more equipment to fail). The age of the line does not appear to significantly lessen its reliability as long as adequatemaintenanceis performed; none of the lines have had a notable increasein

15、the frequency of outages as the lines have aged. As would be expected,the empirical data presentedin Table I confirms the two overhead lines which have been insulated to a higher level (34 or 69 KV) have significantly better reliability records than those utilizing 15 kV class construction. Feeder 7

16、 (insulated to 34 KV) and feeder 8 (insulated to 69 kV) have bad only 3 outages each over their 32 and 23 year life spans, respectively. These lines follow similar terrain and are comparable in length and age to the 15 kV class lines, yet they have a combined failure rate of 0.22 failures per year v

17、ersus 4.32 failures per year for the remaining feeders.On typical 15 kV insulated line construction, lightning flashovers often cause 60 cycle power follow and feeder trip. With the higher insulation construction, outage rates are reduced by limiting the number of flashovers and the resultant power

18、follow which causesan over current device to trip. This allows lightning arresters to perform their duty of dissipating lightning energy to earth. The number of re closer actions and their resultant momentary outages are also reduced. This is beneficial for critical facilities and processes which ca

19、nnot tolerate even momentary outages. An additional benefit is that outagesdue to animal contact are also reduced becauseof the greater distance from phase conductor to ground on pole structures. Distribution line equipment to increase line insulation values are "off the shelf" items and p

20、roven technology. New lightning resistant construction typical by utilizes horizontal line posts, fiberglass standoff brackets or any other method which world increase the insulation value. The replacementof standardpin insulators with line post insulators of greater flashover value is an effective

21、meansto retrofit existing wood cross arm construction. The doubling and tripling of dead end and suspension insulators is also a means of increasing flashover values on existing angle and dead-end structures. Current fiberglass, polymer, and epoxy technologies provide an affordable means to increase

22、line insulation.While the use of increasedinsulation levels to reduce lightning flashovers and the resultant outages on overhead distribution lines has been thoroughly tested and demonstratedin laboratory and experimental tests 5, long term history field data has positively demonstrated that the use

23、 of "lightning resistant" construction can greatly reduce outages. Field use at ORNL has shown that in areas which are vulnerable to lightning, the use of increasedinsulation and a smaller shielding angle is an impressive and cost effective means to appreciably increase the reliability of

24、overhead distribution lines.This reliability study clearly illustrates that the insulationrequirements for high-reliability distribution feeders should be determined not by the 60 Hz operatingvoltage but rather by withstand requirementsfor the lightning transients or other high voltage transients th

25、at are impressed upon the line. Electrical equipment (switchgear, insulators, transformers, cables,etc.) have a reserve (BElevel or flashover value) to handle momentary over voltages, and by increasing that reserve, the service reliability is appreciably increased. As the electrical industry gradual

26、ly moves away from standard wood cross arm construction and moves toward more fiberglass, polymer and epoxy construction, increased insulation methods can be applied as part of new construction or as part of an upgrade or replacement effort. In considering new or upgradedoverhead line construction,

27、the incremental increased cost of the higher insulation equipment is d in proportion to the total costs of construction (labor, capital equipment, cables, electric poles, right-of-way acquisition), Its cost effectiveness varies with the application and the conditions to which it is be applied. Econo

28、mic benefits include increased electrical service reliability and its inherent ability to keep manufacturing processes and critical loads in service. Other more direct benefits include less repair of overhead distribution lines, which can have a significant reduction in maintenance cost due to less

29、replacement materials and a large reduction in overtime hours for maintenancecrews.抗雷擊架空配電線 路的可靠性閃電仍然是架空配電線路上的中斷1 的主要原因。通過(guò)實(shí)驗(yàn)室測(cè)試和現(xiàn)場(chǎng)觀察和測(cè)量，雷擊和其對(duì)配電系統(tǒng)組件的屬性是很好理解的現(xiàn)象。本文提出了一個(gè) 32 年的歷史記錄，停運(yùn)的原因，時(shí) 間，地點(diǎn)，在橡樹(shù)嶺國(guó)家實(shí)驗(yàn)室的八個(gè)配電饋線匯編。配電型避雷器在死胡同和角度的結(jié)構(gòu)被放置在極安裝W 奧 莫爾的位置，并在高點(diǎn)上的架空線。站級(jí)避雷器是用來(lái)保護(hù)地下電纜運(yùn)行，墊置式開(kāi)關(guān)柜，單位變電站變壓器。每個(gè)極接地的接地電阻通常是15

30、 歐姆或更小。在高海拔系統(tǒng)中，基本上是對(duì)地電阻大于15 歐姆， 尤 其是在干燥的夏季。在這些高點(diǎn)，研磨棒極接地系統(tǒng)，在1960 年 ，企圖以減少雷擊停電驅(qū)動(dòng)和保稅。這些嘗試只是部分成功地降低停電率。從浪涌保護(hù)的角度來(lái)看，使用各種不同的桿件結(jié)構(gòu)（列直插式，角，角，死路，等），和 絕緣體及使用的硬件的各種不允許每13.8 千伏架空線具有均勻的沖擊閃絡(luò)分類(lèi)評(píng)價(jià)（170 千伏，等）或 一個(gè)數(shù)值的的BIL 電壓類(lèi)（ 95千伏 BIL， 等等 ）。在 分析中為了簡(jiǎn)單起見(jiàn)，每個(gè)分類(lèi)的額定電壓建筑類(lèi)（ 15 千伏， 34 千伏， 69 千伏）架空線。六七八個(gè)架空線（饋線1 至 6） 建立典型的 REA 標(biāo)準(zhǔn)水

31、平木橫擔(dān)，利用單級(jí)的ANSI 55-5 瓷針 式 絕緣子（標(biāo)稱(chēng)15千伏絕緣）。架 空地線相導(dǎo)線的屏蔽角通常是45 度。一架空線（饋線7） 建 延長(zhǎng)線傳輸型木桿建設(shè)，因?yàn)檫@是已產(chǎn)生的電能反饋到電網(wǎng)的研究設(shè)施。這條 線極結(jié)構(gòu)耐久的建設(shè)的其中利用雙ANSI 52-3 瓷懸式絕緣子支持（標(biāo)稱(chēng)34 千 伏絕緣 ）。饋 線 7 的架空地線的相導(dǎo)體的屏 蔽角通常是30 度。在 1969 年，架空線（饋線8）有意建立“抗雷擊 ”試圖減少雷電造成的停電。該行的極結(jié)構(gòu)階段階段超過(guò) 24 英寸長(zhǎng)的玻璃纖維懸掛支架與 雙 ANSI 52-3 瓷懸式絕 緣 子，支持標(biāo)稱(chēng)69 千伏絕緣的導(dǎo)體。 饋線 8 架空地線的相導(dǎo)體

32、的屏蔽角通常是30 度。編制各八個(gè) 13.8 千伏饋線故 障數(shù)據(jù)列于表I 中， 沿 饋線結(jié)構(gòu)，海拔高度， 長(zhǎng)度，和年齡的相關(guān)信息。故障分析的一個(gè)重要發(fā)現(xiàn)是，與天氣有關(guān)的事件占了一半以上（56）的饋線停電記錄。五十七名76 天氣有關(guān) 的 中斷是由于雷擊。絕緣擊穿損壞，由于雷擊還涉嫌至少有十幾觀察到的設(shè)備故障。數(shù)據(jù)表明架空線路經(jīng)過(guò)地勢(shì)高，是不可靠的，因?yàn)槔讚麸L(fēng)險(xiǎn)更大。例如，饋線3 最錄制中斷（48），其中三分之二是由于與天氣有關(guān)的事件，這也是最高的饋線線廠區(qū)，上升到海拔450 英尺以上的參考山谷高度。也觀察到架空線更長(zhǎng)，更多的變電站和設(shè)備連接不可靠（多接觸雷擊和更多的設(shè)備失敗）。行 的年齡似乎并不顯著減輕其只要足夠的維護(hù) ;線中斷的頻率 有一個(gè)顯著的增加作為線路歲。正如所預(yù)料的，實(shí)證的數(shù)據(jù)列于表我確認(rèn)兩架空線路絕緣已到一個(gè)更高的水平（34 或 69 千伏 ），