外文翻譯--線路故障與距離保護(hù)

1、<p><b>　　附錄</b></p><p><b>　　附錄1中文譯文</b></p><p><b>　　線路故障與距離保護(hù)</b></p><p><b>　　線路故障</b></p><p>　　由于輸電線路是曝露在陽光中并受大氣損害

2、,輸電線路上的故障要比設(shè)備上的故障發(fā)生的頻繁。輸電線路故障被列出，按嚴(yán)重程度分為以下幾種：</p><p>　?。?）帶或不帶故障阻抗的三相故障或三相接地短路故障。最嚴(yán)重但最不普通的這種故障以數(shù)量僅僅是一種。</p><p>　?。?）帶或不帶故障阻抗的兩相短路接地故障。這種故障比三相故障嚴(yán)重性小，但是普通性大。然而，這種故障以數(shù)量是三種。</p><p>　?。?

3、）相間短路故障。這種故障比以上故障普通性大，但是嚴(yán)重性小。這種故障以數(shù)量也是三種。</p><p>　?。?）單相接地故障。這種故障是嚴(yán)重性最小的，但是最普通的一種。這種故障以數(shù)量也是三種。</p><p>　　從以上來看，我們得出結(jié)論：有四種故障類型，以數(shù)量是十種。象三相故障或三相接地短路故障，包括兩或多相的兩相短路接地故障和相間短路故障，這三種故障被認(rèn)為是相故障，即，單相接地故障被叫做

4、接地故障。所有線路故障將把系統(tǒng)帶入不正常的運(yùn)行狀態(tài)，并且很可能損害電氣設(shè)備。因此，故障線必須通過保護(hù)繼電器從系統(tǒng)中切除。</p><p><b>　　距離保護(hù)</b></p><p>　　當(dāng)故障發(fā)生在電力傳輸線上時，保護(hù)系統(tǒng)需要切除故障輸電線路。為了確保可靠并且快速的切除故障線路，具有不同原理的幾種保護(hù)系統(tǒng)經(jīng)常用來保護(hù)一條線路。在它們之間，距離保護(hù)對于電力傳輸線是最重

5、要的一種保護(hù)。</p><p>　　距離保護(hù)的操作依靠下列事實(shí),一旦故障發(fā)生,在電力系統(tǒng)和故障任何點(diǎn)之間的距離與這點(diǎn)電壓對電流的比成比例。在相互連接的網(wǎng)絡(luò)中,那可能有許多電站,在電站電壓電流比是最大值,并且減小不同提供者到故障那幾乎是零。對電壓電流比作出響應(yīng)的繼電器被用在電力系統(tǒng)不同的點(diǎn)來給出到故障的距離的測量或線路的長度。通過安裝繼電器，因此離故障最近的比遠(yuǎn)點(diǎn)的運(yùn)行比較快，控制不同供者的有區(qū)別的短路器已應(yīng)用。通

6、常，三段式距離保護(hù)被用在傳輸線的保護(hù)。</p><p><b>　　標(biāo)準(zhǔn)的三段式保護(hù)</b></p><p>　　普通的距離繼電器用三段測量元件（各自元件或者帶有時間元件來增加前者范圍的第一和第二段的一元件，對于第三段的第二元件）。第一段的元件被設(shè)置覆蓋第一部分的80%到90%，是一個瞬間高速繼電器，然而覆蓋地二部分的大約25%第二段的元件和覆蓋第二部分末端的第三段元

7、件是延時繼電器。第二和第三段的時間繼電器T2、T3由各自的時間繼電器提供。安置小于長度100%的第一段用來避免繼電器伸得過長到一個部分。伸得過長由以下原因發(fā)生：⑴暫態(tài)越過繼電器，⑵繼電器上的毛病，⑶電流互感器和電壓互感器的錯誤，⑷阻抗安置的數(shù)據(jù)錯誤被造成。</p><p>　　第二段的元件主要是給第一部分的末端提供保護(hù)并且也給下一段達(dá)到長度25%遠(yuǎn)后備。由于它可能操作第一部分末端的滅弧故障是合適的。由于中間電流注

8、入源和上面提及的其他誤差的影響，繼電器保護(hù)區(qū)域縮短的可能性也應(yīng)該被考慮。第二部分元件的時間繼電器（T2）幾乎在0.2到0.5秒之間。</p><p>　　第三段元件給臨近線路部分的故障提供后備保護(hù)。在達(dá)不到最大范圍的情況下它的伸長盡可能的超過最大臨近線路部分的末端。第三段時間繼電器（T3）通常在0.4到1.0秒之間。</p><p>　　在許多情況下，例如連貫的線路部分以長度不同，以上方案

9、的代替物，許多的步或者時間繼電器，可能需要最優(yōu)的選擇和保護(hù)。</p><p>　　三段式保護(hù)方案由圖1給出。</p><p>　　附圖1 三段式保護(hù)圖</p><p><b>　　距離保護(hù)的要求</b></p><p>　　距離繼電器有三個基本特征是必須的。它們是：⑴方向的響應(yīng)，⑵阻抗的響應(yīng)，⑶時間。這些特征不是必須有各

10、自的繼電元件提供，但是對于所有的距離方案來說它們基本的。就方向和測量繼電器而言，在任何方案被要求的實(shí)際數(shù)量在三相系統(tǒng)中是被影響的，三相故障、相間故障、相對地的故障、兩相對地故障必須被顧及。</p><p>　　因此，對于提供兩個距離繼電器各自的裝置來說是普通的實(shí)踐，一個相故障的裝置和一個對地故障的裝置。在它們之間這些滿足三相故障和兩相對地故障。這些繼電器的每一套包括三個分部繼電器（一個是每兩相的相故障和一個是每相

11、對地故障）。對于比較早被描述的三段式每一個繼電器由2或3個元件組成。因此距離保護(hù)方案通過許多必須的繼電器是不可避免的復(fù)雜。這些有時減少使用簡單的繼電器對于許多任務(wù)（開關(guān)距離方案），但是象這過分的結(jié)合包含選擇電路并且導(dǎo)致延時操作。相距離方案已經(jīng)不帶任何開關(guān)的被發(fā)展。</p><p><b>　　附錄2 英文原文</b></p><p>　　Faults on Trans

12、mission Lines and Distance Protection</p><p>　　Faults on Transmission Lines</p><p>　　Because transmission lines are exposed to lightning and other atmospheric hazards, faults on them occur more

13、frequently than those in apparatus. The types of faults taking place on a transmission line are listed, in the order of severity, as following:</p><p>　　(1) fault (LLL fault) or to ground fault (LLLG faul

14、t) with or without fault impedance. This fault which is most severe but least common is only one in number.</p><p>　　(2) Double line to ground (LLG) fault with or without fault impedance. This fault is less

15、severe but more common than fault. However, this type of faults is three in number.</p><p>　　(3) Line to line (LL) fault. This fault is more common but less severe than the above fault. These faults are al

16、so three in number.</p><p>　　(4) Single line to ground (LG) fault. This fault is the least severe but the most common one. These faults are also three in number.</p><p>　　From the above, we conc

17、lude that there are four types of faults which are ten in number. The first three faults such as LLL or LLLG, LLG and LL faults involving two or more phases are known as phase fault while the fourth fault, namely, LG fau

18、lt, is called ground fault. All of the line faults will bring the system into abnormal operating conditions, and may damage electrical equipment. Therefore, the faulty lines must be isolated from the system by protection

19、 relays.</p><p>　　Distance Protection</p><p>　　When faults occur on a power transmission line, a protection system is required to isolate the faulted transmission line. To guarantee reliable and

20、 quick isolation of the faulted line, several protection systems with different principles are usually employed to protect one transmission line. Among them, distance protection system is one of the most important protec

21、tions applied for transmission lines.</p><p>　　The operation of distance protection depends on the basic fact that on the occurrence of a fault, the distance between any point in the power system and the fau

22、lt is proportional to the ratio of voltage to current at the point. In an interconnected network in which there may be a number of power stations, the voltage to current ratio is a maximum at the power station and decrea

23、ses along the various feeders to the fault where it is almost zero. Relays responding to this voltage/current ratio can </p><p>　　Standard 3-zone Protection</p><p>　　The conventional distance re

24、laying uses three distance measuring units (physically separate units or one unit for first and second zones with a timing unit to increase the reach of the former and a second unit for the third zone). The first zone un

25、it which is set to cover usually between 80% and 90% of the first section, is an instantaneous high speed relay while the second zone unit which is set to cover about 25% of the second section and the third zone unit whi

26、ch is set to cover up to the end</p><p>　　The main object of the second zone unit is to provide protect to the end zone of the first section and also to give remote back-up to the next section up to about 25

27、% of its length. It should be adjusted such that it will be able to operate even for arcing faults at the end of the first section. Also the tendency to underreach by the relay due to the effect of intermediate current s

28、ources and the other errors as mentioned above should be taken into account. The time delay (T2) with the second </p><p>　　The third zone unit provides backup protection (remote) for faults in the adjoinin

29、g line sections. As far as possible its reach should extend beyond the end of the largest adjoining line section under conditions that cause the maximum amount of underreach, namely arcs and intermediate current sources.

30、 The third zone time delay (T3) is usually between 0.4 and 1.0s.</p><p>　　In many cases, where the consecutive line sections differ very much in length, alterations in the above scheme, in the number of step

31、s or time delays, may be necessary to give optimum selectivity and protection.</p><p>　　A schematic diagram of a 3-zone protection scheme is given by Fig.1.</p><p>　　Fig.1 Schematic diagram of 3

32、-zone protection</p><p>　　Distance Protection requirements</p><p>　　Three basic features are necessary from distance relays. They are:(ⅰ)response to direction, (ⅱ)response to impedance,(ⅲ)timing

33、. These features need not necessarily be provided by the separate relay elements but they are fundamental to all distance schemes. As far as the directional and measuring relays are concerned, the actual number required

34、in any scheme is governed by the consideration that in a three phase system, three phase, phase-to-phase, phase-to-earth and double phase-to-earth faults </p><p>　　It is common practice therefore to provide

35、two separate sets of distance relays, one set for phase faults and the other set for earth faults. These between them cater for three phase and double phase-to-earth faults. Each set of these relays contains three indivi

36、dual relays (one for each pair of phases for phases for phase fault scheme and one for each phase for the earth fault scheme). Each relay again consists of 2 or 3 elements for the three-zone scheme as described earlier.