外文翻譯--變電站與電力系統(tǒng)繼電保護(hù)

- 1 - 中文 3826 字 附錄 1：外文資料翻譯 A1.1 Substation and Power System Protection With the development of undertaking of the electric wire netting , the pattern of national network has already taken shape basically. Scientific and technological level raise, electric environmental protection can strengthen, make scientific and technological competence and advanced international standards, Chinese of power industry close day by day. Electric management level and service level are being improved constantly, strategic planning management of electric power development, production operate manage , electric market administration and electric information management level , high-quality service level ,etc. general to raise enterprise. The purpose of a substation is to transform the characteristics of the electrical energy supplied to some form suitable for use, as for example, a conversion from alternation current to direct current for the use of city railway service, or a change from one voltage to another, or one frequency to another. Their functions include: Tap. TO be economical, transmission of larger amounts of power over long distances must be done at voltages above 110,000 volts. Substations for supplying small amounts of power from such high-voltage lines are not satisfactory from the standpoint of operation and are also uneconomical. It is, therefore, common practice to install a few substations at advantageous points along the high-tension lines and step down the high-transmission voltage to a lower secondary-transmission voltage from which numerous small loads may be supplied. Distribution. Any substation that is used to transform electrical energy to a potential that is low enough for general distribution and utilization is a distributing substation. Such a substation will generally receive its energy over a few comparatively high-tension lines and distribute it over a large number of low-voltage lines. Industrial. When fairly large blocks of power are required by industrial plants, it often becomes necessary and advisable to install an individual substation to supply such a load directly from the main high-voltage line or secondary line of lower voltage. Its simplest form would comprise only switching equipment, there being no voltage transformation. In most cases a voltage transformation is probably needed; hence transformer equipment is included. Sectionalizing. In very long high-voltage large capacity lines, particularly when several circuits are run in parallel, it is often necessary to split the lines into sections, in order that proper protection to the line and service can be obtained. Such a substation is , therefore, helpful in sectionalizing damaged sections of a line, providing continuity of service. Such a substation will generally comprise only switching equipment. In long lines it may also serve to supply power-factor-correcting equipment. Transmission-line Supply. It is becoming more and more common to install the high-tension equipment of a - 2 - power plant outdoors, the installation becoming nothing more than a step-up substation receiving its power at generator voltage, then stepping up its voltage and finally sending it out over high-voltage transmission lines. Such a substation is nothing more than an outdoor distributing substation turned around, the voltage being stepped up instead of stepped down. Power-factor Correction. The voltage at the end of long lines tends to increase as the load supplied is decreased, while on the other hand it tends to decrease as the load is increased. Owing to the inductance and capacity effects, this variation in voltage is accompanied by a wide variation in power factor of a line, it is necessary to use synchronous condensers at the end of the line. To supply such a machine the transmission-line voltage must be stepped down, hence a power-factor-correcting substation will include switching equipment, transformers, and all equipment necessary for the operation of synchronous condensers. Railway. Substations supplying railways may be generally classified under two heads, namely, as alternating current and as direct current. In the cases of alternating-current substations the problem is generally one of voltage transformation and of supplying single-phase power to the trains. It is, however, possible to supply single-phase to three-phase inside the locomotive by the use of a phase converter. In the case of direct-current railways, the substations are generally supplied whit three-phase power and converted to direct current by means of rotary converters, motor-generator sets, or rectifiers. Direct current for Light and Power. There are still a few sections in some of out large cities, which are supplied with direct-current three-wire systems. Such a supply is invariably obtained from synchronous converters. There are also certain types of motor loads in industrial plants, which require direct current. Because many cities have experience rapid growth, their substations have often reached the limits of their capacity. As a result, downtown distribution systems are often overworked and many need a major, overhaul, overhaul, or expansion. However, space is scarce. Downtown business owners do not want “ugly” new substation marring the areas appearance, but nor do businesses and residents grid the prospect of grid disturbances. One example of a system capable of integrating equipment monitoring with substation automation is the GE Harris integrated Substation Control System (ISCS). The system can integrate data from both substation system and equipment online monitoring devices into a common data base. The data can then be processed by an expert system into information on the status and health of monitored equipment using self-diagnostic programs. This information is then sent to a CMMS for automatic generation and tracking of maintenance work orders leads directly to the significant efficiencies found with condition-based maintenance programs. ABB Power and its industry partners have combined to develop the ABB Power System software. The system contains a diagnostic and maintenance system that reports necessary maintenance before failure. It allows utilities and industrial customers to easily expand from a single computer to a full system, without re-engineering. the directional protection basis Early attempts to improve power-service reliability to loads remote from generation led to the dual-line concept. Of course, it is possible to build two lines to a load, and switch the load to whichever line remains energized after a - 3 - disturbance. But better service continuity will be available if both lines normally feed the load and only the faulted line is tripped when disturbances occur. Fig.14-1 shows a single-generator, two-line, single-load system with breakers properly arranged to supply the load when one line is faulted. For the arrangement to be effective it is necessary to have the proper relay application. Otherwise, the expensive power equipment will not be able to perform as planned. Consider the application of instantaneous and/or time delay relays on the four breakers. Obviously the type of the relay cannot coordinate for all line faults. For example, a fault on the line terminals of breaker D. D tripping should be faster than B, however, the condition reverses and B should be faster than D. It is evident that the relay protection engineer must find some characteristic other than time delay if relay coordination is to be achieved. The magnitude of the fault current through breakers B and D is the same, regardless of the location of the fault on the line terminal of breaker B or D. Therefore relay coordination must be based on characteristics other than a time delay that starts from the time of the fault. Observe that the direction of current flowing through either breaker B or D is a function of which line the fault is on. Thus for a fault on the line between A and B, the current flows out of the load bus through breaker B toward the fault. At breaker D the current flows toward the load bus through breaker D. In this case breaker B should trip, but breaker D should not trip. This can be accomplished by installing directional relays on breakers B and D that are connected in such a way that they will trip only when current flows through them in a direction away from the load bus. Relay coordination for the system shown in Fig.14-1 can now be achieved by their - salvations of directional over current time delay relays on breakers B and D. Breakers A and C can have no directional over current time delay relays. They may also now have instantaneous relays applied. The relays would be set as follows: The directional relays could be set with no intentional time delay. They will have inherent time delay. The time delay over current relays on breakers A and C would have current settings that would permit them to supply backup protection for faults on the load bus and for load equipment faults. The instantaneous elements on breakers A and C would have current settings that would not permit them to detect faults on the load bus. Thus the lines between the generator and the load would have high-speed protection over a considerable portion of their length. It should be observed that faults on the line terminals of breakers A and C can collapse the generator voltage. The instantaneous relays on breakers A and C cannot clear the circuit instantaneously, because it takes time for power equipment to operate. During this period there will be little or no current flow through breakers B and D. Therefore, B or D cannot operate for this fault condition until the appropriate breaker at the generating station has operated. This is known as sequential tripping. Usually, it is acceptable under such conditions. Direction of current flow on an a. c. system is determined by comparing the current vector with some other reference vector, such as a voltage vector. In the system of Fig. 14-1 the reference voltage vector would be derived from the voltages on the load bus. Direction of current or power flow cannot be determined instantaneously on a. c. systems whose lines and equipment contain reactance. This is apparent from the fact that when voltage exists, the lagging current can be plus or minus or zero, depending on the instant sampled in the voltage cycle. Accordingly, the vector quantities must be sampled over a time period. The time period for reasonably accurate sampling may be from - 4 - one-half to one cycle. Work is proceeding on shorter sampling periods where predicting circuits are added to the relay to attempt to establish what the vectors will be at some future time. The process is complex, because it must make predictions during the time when electrical transients exist on the system. Usually, the shorter the time allowed for determining direction, the less reliable will be the determination. differential protection Much of the apparatus used on a power system has small physical dimensions when compared to the length of general transmission-line circuits. Therefore, the communications between the apparatus terminals may be made very economically and very reliably by the use of direct wire circuit connections. This permits the application of a simple and usually very effective type of differential protection. In concept, the current entering the apparatus is simply compared against the current leaving the apparatus. If there is difference between the two currents, the apparatus is tripped. If there is no difference in the currents, the apparatus is normal and no tripping occurs. Such schemes can usually be made rather sensitive to internal faults and very insensitive to external faults. Therefore, relay coordination is inherent in the differential relay scheme. The simplest application of differential relaying is shown in Fig. 14-4. Here one simple power conductor is protected by a differential relay. The relay itself usually consists of three coils, one of which is the coil that detects the difference current and initiates circuit tripping. It is called the operating coil and is designated by an O in the figure. The other two coils are restraint coils and are designated by R in the figure. The restraint coils serve a practical purpose. They prevent operation for small differences in the two current transformers that can never be exactly identical, as a result of manufacturing and other differences. Otherwise, the restraint coils serve no theoretical purpose. Fig. 14-4 shows the condition of current flow for an external fault during which the relay should not trip. The current I1 enter and leaves the power circuit without change. The current transformers are assumed to have a 1 : 1 ratio for simplicity, and their secondary windings are connected to circulate the I1 currents through the restraint coils of the differential relay only. If current left or entered the power circuit between the two current transformers (an internal fault), then the currents in the transformers would be different, and the difference current would flow through the operating coil of the relay. - 5 - 本文譯自電力英語閱讀 - 6 - A1.2 變電站與電力系統(tǒng)繼電保護(hù) 隨著電力電網(wǎng)事業(yè)的發(fā)展，全國聯(lián)網(wǎng)的格局已基本形 成?？萍妓降玫教岣撸娏Νh(huán)境保護(hù)得以加強(qiáng)，使中國電力工業(yè)的科技水平與世界先進(jìn)水平日漸接近。電力管理水平和服務(wù)水平不斷得到提高，電力發(fā)展的戰(zhàn)略規(guī)劃管理、生產(chǎn)運(yùn)行管理、電力市場營銷管理以及電力企業(yè)信息管理水平、優(yōu)質(zhì)服務(wù)水平等普遍得到提高。 變電站的目的是改變電能特性以滿足使用要求。例如，從交流轉(zhuǎn)換為直流為城市鐵路供電，或者從一個(gè)電壓等級轉(zhuǎn)換為另一十電 S等級，或者從一個(gè)頻率轉(zhuǎn)換為另一個(gè)頻率。變電站的功能包括： 分支 為了經(jīng)濟(jì)性，大容量電力的遠(yuǎn)距離傳輸必須在 110kV 以上的電壓下進(jìn)行。從運(yùn)行的角度來看，從這樣的 高壓線直接引出向小容量負(fù)荷供電的變電站是不能令人滿意的，也是不經(jīng)濟(jì)的。因此，一個(gè)常規(guī)辦法是：沿著高壓線路在適合的地點(diǎn)設(shè)置一些變電站，將高傳輸電壓降到一個(gè)較低的二級傳輸電壓，從這個(gè)電壓向小容量負(fù)荷供電。 配電 任何用于將電能變換為可以直接配電和利用的較低壓等級的電能的變電站都是配電變電站。這樣的變電站一般將從 A條電壓相對高的線路接受電能，并向大量較低電壓線路配送電能。 工業(yè) 當(dāng)工廠需要大量電能時(shí)，設(shè)置一個(gè)自己的單獨(dú)的變電站是有必要的也是明智的，這個(gè)變電站直接從主高壓線路或較低電壓的二級輸電線路取得電能。 其最簡單的形式?jīng)]有電壓的轉(zhuǎn)換，只由開關(guān)設(shè)備組成。但是，在大多數(shù)情況下需要一個(gè)電壓轉(zhuǎn)換，因此工業(yè)變電站應(yīng)該包括變壓器設(shè)備。 分段 在很多高壓大容量的長線路中，尤其是幾條線路并聯(lián)運(yùn)行時(shí)，經(jīng)常需要將線路分段，目的是為了使線路獲得適當(dāng)?shù)谋Ｗo(hù)和維護(hù)。這樣的變電站有助于隔寓線路中的故障段，保證連續(xù)供電。這種變電站通常只由開關(guān)設(shè)備組成。在長線路中，還可以提供功率因數(shù)調(diào)整設(shè)備。 輸電線路的電源 在發(fā)電廠的戶外設(shè)置高壓設(shè)備已經(jīng)變得越來越昔遍，安裝的裝置只不過是一個(gè)升壓電站，它以發(fā)電機(jī)電壓接受電能，然后將電壓升高，并最終通 過高壓輸電線路將電能送出。這種變電站只不過是將戶外配電變電站反過來，電壓是被升高而不是降低。 功率因數(shù)調(diào)整 隨著供電負(fù)荷的減小，長線路末端的電壓趨向于升高，而隨著供電負(fù)荷的增大，線路末端的電壓趨向于降低。由于電感和電容的影響，這個(gè)電壓的變化將伴隨著線路功率因數(shù)而變化，因此有必要在線路末端設(shè)置同步調(diào)相機(jī)。為了向同步調(diào)相機(jī)供電，就必須將高壓輸電線路的電壓降低，因此，一個(gè)功率因數(shù)調(diào)整變電站將包括開關(guān)設(shè)備、變壓器和所有運(yùn)行同步調(diào)相機(jī)所需要的設(shè)備。 鐵路 一般地，向鐵路供電的變電站分為兩類，即交流類和直流類。如果 是交流變電站，其問題一般是一個(gè)電壓轉(zhuǎn)換和向鐵路機(jī)車負(fù)荷單相供電的問題。然而，也有可能在機(jī)車內(nèi)通過相位變換錨由單相電源向三相負(fù)荷供電。如果是直流鐵路，這種變電站一般由三相電源供電，并通過旋轉(zhuǎn)變流器、電動(dòng)機(jī) 發(fā)電機(jī)組或者整流器等將交流變換為直流。 照明和動(dòng)力用直流 現(xiàn)在，仍然有一些在大城市以外的地區(qū)采用直流三線系統(tǒng)供電，這種電源總是從 - 7 - 同步換流器獲得。另外，工廠中還有某些類型的電動(dòng)機(jī)負(fù)荷要求采用直流電源，這些一般都是由旋轉(zhuǎn)換流器供電。對于電解工業(yè)，低壓直流電源絕對是必須的，因此也需要使用電動(dòng)機(jī) 發(fā)電機(jī)組或 旋轉(zhuǎn)變記器。 由于城市不斷發(fā)展，許多城市變電站已經(jīng)達(dá)到其負(fù)荷極限，所以市區(qū)配電系統(tǒng)經(jīng)常是超負(fù)荷運(yùn)行，許多配電站急需升級、檢修或擴(kuò)建，問題是空間不足。市中心的業(yè)主不希望外觀“丑陋”的新變電站影響當(dāng)?shù)氐木坝^，商家和居民也不想將來被星羅棋布的電網(wǎng)所干擾。 變電站自動(dòng)化的新趨勢是狀態(tài)維修。 ABB公司與聯(lián)邦愛迪生公司合作開發(fā)了一套貫穿整個(gè)系統(tǒng)的規(guī)劃，一旦聯(lián)邦愛迪生公司的配電系統(tǒng)發(fā)生故障，可使電能流向發(fā)生改變。聯(lián)邦愛迪生公司的項(xiàng)目總裁邁克羅維說：“對這幾個(gè)變電站的發(fā)行包括肥現(xiàn)有的輻射狀的饋電系統(tǒng)改成環(huán)形母線系統(tǒng)，以增 加系統(tǒng)的穩(wěn)定性。” GE 哈里其變電站綜合控制系統(tǒng)（ ISCS）就是一個(gè)將設(shè)備監(jiān)測與變電站自動(dòng)化相結(jié)合的系統(tǒng)。該項(xiàng)系統(tǒng)能夠?qū)碜宰冸娬鞠到y(tǒng)和設(shè)備在線監(jiān)控裝置的數(shù)據(jù)進(jìn)行綜合，并輸入數(shù)據(jù)庫，然后由一個(gè)專家系統(tǒng)利用自我診斷程序進(jìn)行分析，得出有關(guān)被監(jiān)測設(shè)備的運(yùn)行善的信息。該信息被發(fā)送到電腦維修管理系統(tǒng)，自動(dòng)發(fā)出并傳送維修工作指令。由于維修指令的發(fā)送得到了改善，極大地提高了基于狀態(tài)進(jìn)行維修程序的效率。 ABB電力公司及其企業(yè)合作伙伴聯(lián)合開發(fā)了 ABB電力系統(tǒng)軟件。該系統(tǒng)包括一套診斷維修系統(tǒng)，能夠在出現(xiàn)故障前提交必要的維修報(bào)告 。有了這一套系統(tǒng)，電力公司和用電單位不須經(jīng)過重新改造，只需一臺(tái)電腦，就能輕而易舉地?fù)碛幸惶淄暾南到y(tǒng)。 方向保護(hù)基礎(chǔ) 早期，對于遠(yuǎn)離發(fā)電站的用戶，為改善其供電的可靠性提出了雙回線供電的設(shè)想。當(dāng)然。也可以架設(shè)不同的兩回線給用戶供電。在系統(tǒng)發(fā)生故障后，把用戶切換至任一條正常的線路。但更好的連續(xù)供電方式是正常以兩回線同時(shí)供電。當(dāng)發(fā)生故障時(shí)，只斷開故障線。（圖 14-1） 所示為一個(gè)單電源、單負(fù)載、雙回輸電線系統(tǒng)。對該系統(tǒng)配置合適的斷路器后，當(dāng)一回線發(fā)生故障時(shí)，仍可對負(fù)載供電。為使這種供電方式更為有效，還需配置合適的 繼電保護(hù)系統(tǒng)，否則，昂貴的電力設(shè)備不能發(fā)揮其預(yù)期的作用?？梢钥紤]在四個(gè)斷路器上裝設(shè)瞬時(shí)和延時(shí)起動(dòng)繼電器。顯然，這種類型的繼電器無法對所有線路故障進(jìn)行協(xié)調(diào)配合。例如，故障點(diǎn)在靠近斷路器 D的線路端， D跳閘應(yīng)比 B快，反之， B應(yīng)比 D快。顯然，如果要想使繼電器配合協(xié)調(diào)，繼電保護(hù)工程師必須尋求除了延時(shí)以外的其他途徑。 無論故障點(diǎn)靠近斷路器 B 或 D 的哪一端，流過斷路器 B 和 D