0241-某精細化工廠高配所及全廠配電系統(tǒng)設計【全套8張CAD圖】,全套8張CAD圖,精細,化工廠,所及,全廠,配電,系統(tǒng),設計,全套,cad 翻譯文獻（英譯中） 原文: Fault—clearing Protective Relays(1) ??? Overcurrent relaying．Slow—speed relays．The most obvious effect of a fault is to change the current in the faulted conductor from a normal value to an abnormally large one．Therefore it is not surprising that the earliest methods of clearing faults were based on the utilization of that effect(overcurrent)．Early methods included fuses，circuit breakers with ?series trip coils，and slow—speed overcurrent relays． ??? ??? Slow—speed overcurrent relays are mostly of the induction type．To obtain selectivity without unnecessarily long delay，such relays usually have a delay which varies inversely with the current．Both time and current settings are adjustable．Since the fault current decreases，on account of the increased impedance of the line between the fault and the source． as the fault is mo，ved farther from the source of power，it follows that the relay operating time increases as the distance to the fault increases. ??? ???? The time—distance curves change with such conditions as connected generating capacity and the connection or disconnection of other transmission lines，and therefore，to ensure selectivity，curves should be checked for several conditions to ascertain that．under the worst condition，an adequate interval exists between the operating times of relays 1 and 3，and, similarly，between each pair of relays on adjoining line sections．Coordination may be accomplished by judicious choice of both time settings and current settings． ??? ???? If the relay current changes but little with fault location，the curve of relay time versus fault position becomes more like curve a than ike curve b．Such a condition is likely to exist if the impedance of the protected section is small compared with the impedance between the generators and the protected section，as may well be true if the section is short and is fed ?solely or principally from one end．Moreover curve a may hold even though the relay current does change with fault location，if，as is usually true，the relays are operating on the minimum-time part of their time—current characteristic．Curve a represents an undesirable condition when several protected line sections are in cascade，because the relay time of the lines ?near the source of power becomes increasingly long． ??? ???? If a line section is long or has power sources at each end，the relay current will vary considerably with fault location．But，even if the current varies enough to give a curve like b，the operating time of a relay near the generator is usually somewhat longer than that of a relay farther from the generator，though not so much longer as in curve a． ??? ???? By the use of graded time settings，overcurrent relays can always be made to work selectively on a radial transmission or distribution system．With graded settings，and with the addition of directional relays，overcurrent relays can be made to work selectively on a loop system fed from one point．But on a loop fed sometimes from one point and sometimes from another，or on a network more complex than a loop，it is difficuh，if not impossible，to choose settings for overcurrent relays so that the relays will work selectively for all fault locations and for all operating conditions． ? 譯文: 故障切除繼電保護裝置(1) ??? 現(xiàn)在來談談過電流繼電保護裝置，特別是延時過電流繼電保護裝置。故障出現(xiàn)時，最明顯的變化是故障導體中的電流由正常的電流值變?yōu)榉钦５拇箅娏?。因此，故障切除所采用的早期方法就是以電流的變化為依?jù)。早期所使用的手段包括熔絲、串聯(lián)跳閘線圈斷路器和延時過電流繼電器。 ??? ?? 延時過電流繼電器大都是感應型，為了滿足選擇性和速動性，這種繼電保護器通常具有反時限特性。時間和電流整定都具有可調性，由于故障電流較小，當故障離電源較遠時，考慮到故障與電源之間線路的阻抗較大，繼電器的動作時間會隨著故障距離的增加而延長。 ??? ?? 時間與距離曲線是依據(jù)連接的發(fā)電容量與以其它線路連接或中斷的狀態(tài)而變化的。因此，為確保選擇性應校驗曲線，保證在嚴重的狀態(tài)下，繼電器#1和#3動作時間之間有適當?shù)臅r間間隔。在相鄰的線路上每一對繼電器之間也同樣要有時間間隔，這種配合通過恰當選擇時間與電流的整定值來完成。 ??? ?? 假如繼電器中的電流由于故障而改變，但變化不大，那么故障點對應的時間的曲線變化與a曲線更相像。假如被保護線路的阻抗與發(fā)電機和保護線路之間的阻抗相比較小時，就能呈現(xiàn)與a曲線相似的這樣一種狀態(tài)。如線路較短，又是單電源供電或主要從一端供電，情況也是如此。此外，即使繼電器中的電流隨故障點變動而改變，a曲線仍可能保持不變。如果繼電器進行瞬時動作，通常情況也是如此。當幾條被保護線路進行串聯(lián)時，a曲呈現(xiàn)著不理想的狀態(tài)，因為靠近電源的線路繼電器動作時間相應變長。 ??? ??? 如果一條線路較長或每一端都有電源，繼電器的電流就會隨故障點的不同將作相應的改變。但即使電流的改變足以像b曲線，靠近發(fā)電機的繼電器動作時間也比距發(fā)電機較遠的繼電器動作時間長，但不如a曲線的時間長。 ??? ??? 通過采用階段時間配置，過電流繼電保護裝置能在輸電系統(tǒng)或配電系統(tǒng)中有選擇性地工作，使用階段配置并利用方向性繼電器，過電流繼電器從單電源供電系統(tǒng)中有選擇性地工作，但在單回線從一端或從另一端供電的線路中，或在一個比一條線路更復雜的網(wǎng)絡中，要想使這種繼電裝置對一切故障和動作狀態(tài)進行選擇性工作，對過電流繼電裝置的整定值的確定，將不是一件容易的事 原文： Fault—clearing Protective Relays(2) ??? High—speed relays．It has already been noted that the relay current during a fault usual． 1y decreases as the distance to the fault location increases．When this location is exactlv at ?the far end of the protected section，the relay current has fl certain value，and，provided that ?other conditions are constant，fl relay current exceeding this value is fl certain indication of a ?fault in the protected section——a condition for which the circuit breaker should be tripped． Tripping may be accomplished under these conditions by the use of fl high—speed overcurrent ?relay having a pick-up current equal to the current produced by fl fault at the distant end of ?the section．In practice，the balance point of the relay·(that is，the fault location that will ?just make the relay pick up)must be somewhat closer than the distant end，for reasons a1一 ready discussed．The contacts of the high—speed relay are connected in parallel with the con— tacts of a slow-speed overcurrent relay so that。either relay can trip the circuit breaker．FauIts ?closer to the relay location than the balance point of the high—speed relay are cleared by this ?relay．Clearing of faults farther away(that is，in the end zone)and back—up protection of the ?next section are accomplished by the slow—speed relay． ??? The chief weakness of high—speed overcurrent relaying is that the balance point varies ?with the type of fault and with conditions outside the protected section，such as the connect— ed generating capacity and the opening or closing of other transmission lines．For example。a three—phase fault usually results in greater fault current than a line—to：line fauIt at the same ?place．Hence，in order to produce equal currents in an overcurrent relay，the three-phase fault must be farther from the relay than the line-to—line fault．In other words，the balance ?point for a three—phase fault is farther from the relay than is the balance point for a line-to— line fault．Again，the additional generating capacity，or the closing of an additional transmis— sion line，may decreasfi the impedance between the sources of power and the fauIt position． thereby increasing the fault current for a given type and location of fault，or，in other words， shifting the balance point farther away from the relay．To assure selective relay action。the ?balance point must never be permitted to move OUt of the protected section under the most ?severe fault conditions．If the high—speed overcurrent relay is set so that this danger is avoid— ed，then the balance point must shift and cover fl considerable distance towards the relav un- der less severe fault conditions，giving a long end zone，in which faults are cleared with de— lay，and a short——perhaps Vanishing——zone in which fauIts are cleared rapidly．It is ap— parent that high—speed overcurrent relays can not be depended upon to clear faults consistent— ly over a large portion of the line unless external conditions are fairly constant．Neverthe— less，the addition of a high～speed overcurrent relay to an existing slow—speed overcurrent re— lay installation will effect more or less improvement in the average speed of clearing faults． ? 譯文： 故障切除繼電保護裝置（2） 瞬時電流速斷保護：繼電器中的電流隨著故障點離保護裝置外的距離的增加而減小，當故障恰好發(fā)生在速斷保護區(qū)末端時，繼電器的整定值固定。假設其他條件不變，如果流過繼電器的電流超過這個整定值，那就表明故障一定在本保護區(qū)內(nèi)，斷路器應跳閘。跳閘動作時通過瞬時電流速斷實現(xiàn)的，即繼電器的整定值與被保護線路末端的故障電流要相等。實際上，繼電保護的動作邊界(使繼電器恰好動作的故障點)必須比末端距離近些。詳細的原由已作過論述。瞬時保護裝置的觸點是與延時保護裝置的觸點并聯(lián)的，為的是任何一段保護動作都能使斷路器跳閘。當故障在瞬時電流速斷保護區(qū)內(nèi)時，該故障由瞬時速斷保護切除，而對于遠距離故障的切除(即末端線路上)和對下一段線路的后備保護則是由延時保護完成的。 ??? 瞬時過電流保護器的主要缺點，在于動作邊界隨故障類型和被保護線路以外的各種條件 的變化而改變。諸如：機組并列增加發(fā)電容量和其它輸電線路的打開與閉合。例如，三相電故障比在同一地點的相間故障通常導致更大的故障電流。因此，為了使過電流器中的電流相等，三相故障點必須比相間線路故障點距繼電器的位置要遠。也就是，三相故障的動作邊界比相間故障的動作邊界離繼電器遠。另一方面，增加發(fā)電容量或關閉附加輸電線路會減少電源與故障點間的阻抗，因而在給定故障類型和故障點的情況下，增大故障電流。換句話說，讓動作邊界離繼電器更遠。為獲得繼電器保護的選擇性，動作邊界在最嚴重的故障狀態(tài)中進行整定，決不允許超出被保護線路以外。如果安裝瞬時速斷保護，這種情況就可以避免(動作邊界超出被保護線路之外)。故障不嚴重，動作邊界相應地縮小。在末端很長范圍內(nèi)的故障要由延時保護器切除．在短的(或許已有消失的)范圍內(nèi)，故障可被迅速切除。除非外部條件相當穩(wěn)定，顯然不能完全依靠瞬時過電流保護器連續(xù)大范圍地進行故障切除。然而，在延時過電流繼電器上裝配瞬時過電流繼電器將會相應提高故障切除速度。