电力系统故障中英文对照外文翻译文献
电力系统继电保护外文及翻译
Power System ProtectionsThe steady-state operation of a power system is frequently disturbed by various faults on electrical equipment. To maintain the proper operation of the power system, an effective, efficient and reliable protection scheme is required. Power system components are designed to operate under normal operating , due to any reason, say a fault, there is an abnormality, it is necessary that there should be a device which senses these abnormal conditions and if so, the element or component where such an abnormalityhas taken place is removed, . deleted from the rest of the system as soonas possible. This is necessary because the power system component can never be designed to withstand the worst possible conditions due to the fact that this will make the whole system highly uneconomical. And therefore, if such an abnormality takes place in any element or component of the power system network, it is desirable that the affected element/component is removedfrom the rest of the system reliably and quickly in order to restore powerin the remaining system under the normal condition as soon as possible.The protection scheme includes both the protective relays andswitching circuits, . circuit breakers. The protective relay whichfunctions as a brain is a very important component. The protective relay is a sensing device, which senses the fault, determines its location and then sends command to the proper circuit breaker by closing its trip coil. The circuit breaker after getting command from the protective relay disconnects only the faulted element. this is why the protective relay must be reliable, maintainable and fast in operation.In early days, there used to be electromechanical relay of induction , very soon the disk was replaced by inverted cup, cylinder and the newrelay obtained was known as an induction cup or induction cylinder relay. This relay, which is still in use, possesses several important featuressuch as higher speed; higher torque for a given power input an more uniform torque.However, with the advent of electronic tubes, electronic relays having distinct features were developed during 1940s. With the discovery of solidstate components during 1950s, static relays with numerous advantages were developed. The use of digital computers for protective relaying purposes has been engaging the attention of research and practicing engineers since layer 1960s and 1980s. Now, the microprocessor/mini computer-based relaying scheme, because of its numerous advantages such as self –checking feature and flexibility, has been widely used in power system all over the world.The overall system protection is divided into following sections:(i)Generator protection,(ii)Transformer protection,(iii)Busprotection,(iv)Feeder protection,(v)Transmission line protection.Basic Requirements to Protective RelaysAny protection scheme, which . required to safeguard the power system components against abnormal conditions such as faults, consists basically of two elements(i)Protective relay and (ii) Circuit breaker .The protective relay which is primarily the brain behind the whole scheme plays a very important role. Therefore proper care should be taken in selecting an appropriate protective relay which is reliable, efficient and fast in operation. The protective relay must satisfy the following requirements:⑴ since faults on a well designed and healthy system are normallyrare, the relays are called upon to operate only occasionally. Thismeans that the relaying scheme is normally idle and must operatewhenever fault occurs. In other words, it must be reliable.⑵ Since the reliability partly depends upon the maintenance, therelay must be easily maintainable.⑶ The palpation of the relay can be in two ways. One is the failureto operate in case a fault occurs an second is the relay operationwhen there is no fault. As a matter of fact, relay must operate ifthere is a fault and must not operate if there is no fault.⑷Relaying scheme must be sensitive enough to distinguish betweennormal and the faulty system.Protective RelaysThe function of the protective relay is to sense the fault and energize the trip coil of the circuit breaker. The following types of the protective relays are used for the apparatus such as synchronous machines, bus bar, transformer and the other apparatus and transmission line protection.(1) Over current relays,(2) Under voltage relays,(3) Under frequency relays,(4) Directional relays,(5) Thermal relays,(6) Phase sequence relays such as(i)negative sequence relays and,(ii)zero sequence relays,(7) Differential relays and percentage differential relays,(8) Distance relays such as (I)plane impedance relays,(ii)angleimpedance relay, . Ohm or reactance relays,(iii)angleadmittance relays,. Mho relays and ,(iv)offset and restrictedrelays,(9)Pilot relays such as (i) wire pilot relays,(ii)carrier channelpilot relays,(iii)microwave pilot relays. There are different types of the relaying scheme based on construction. Theyare:(i)electromechanical type,(ii)thermal relays,(iii) transduction relays,(iv)rectifier bridge relay,(v)electronic relays,(vi)digital relaying schemes.电力系统继电保护电力系统的稳态运行经常会因各种电力设备配故障原因而被扰乱。
电网事故外文翻译
英文原文名Power grid intelligent prevention 中文译名电网安全智能防护英文原文版出处：Electric & energy system T-Franc ISSN 0740-624X 2007（24）译文成绩：指导教师（导师组长）签名：译文：在大型电力系统中，严重的局部故障可以导致电力系统的不稳定现象，如发电机组的不同步(失步)、电力供需不平衡、电力频率和电压等指标偏离额定范围等。
这些现象的发展可能造成事故的扩大乃至全电网的崩溃，大范围的供电中断，造成严重的经济损失。
在这种情况下，需要及时采取有效的紧急控制措施以避免电力系统的崩溃瓦解。
解列是一种有效地避免电力系统异步运行甚至崩溃的控制措施，其基本的思想是通过主动地切断一些合理选择的输电线将整个电力网分解为若干个互相之间异步的电力孤岛，使全系统工作在一个“准正常”的状态，即各孤岛内部发电机组同步运行。
电力供需平衡，满足其他必要的安全约束条件（相对于事故前正常运行的电力系统，某些约束条件和指标可相应放宽），这样，在其他紧急控制措施的配合下，各孤岛内的子电力系统仍能保持供电，从而避免电力系统崩溃而造成的巨大的经济损失。
而在系统故障排除之后，通过恢复控制手段重新同步各个电力孤岛，可以恢复电网的完整性和全系统正常运行。
因此，在某种意义上说，解列控制是在灾变事故发生的情况下保障电力系统安全运行的最后防线。
本发明针对有可能造成电网异步甚至电网崩溃的事故，针对大规模电网，首次基于有序二元决策OBDD技术提出了合理的解列策略的方法，为灾变事故下避免电力系统的崩溃提供了一种方法。
对历史上所发生的一些知名的大型电力网崩溃事故(例如1965年美国东北部电力中断、1977年纽约电力崩溃、1996年美国西部电力系统崩溃、1999年巴西电力中断事故等)的研究表明：由于未能及时并正确地选择解列策略，即选择合理的解列点，以至于整个电力系统的崩溃，造成大区域的供电中断，造成了数以几十亿美元的经济损失。
电力系统中英文翻译
LINE PROTECTION WITH DISTANCE RELAYSDistance relaying should be considered when overcurrent relaying is too slow or is not selective. Distance relays are generally used for phase-fault primary and back-up protection on subtransmission lines, and on transmission lines where high-speed automatic reclosing is not necessary to maintain stability and where the short time delay for end-zone faults can be tolerated. Overcurrent relays have been used generally for ground-fault primary and back-up protection, but there is a growing trend toward distance relays for ground faults also.Single-step distance relays are used for phase-fault back-up protection at the terminals of generators. Also, single-step distance relays might be used with advantage for back-up protection at power-transformer tanks, but at the present such protection is generally provided by inverse-time overcurrent relays.Distance relays are preferred to overcurrent relays because they are not nearly so much affected by changes in short-circuit-current magnitude as overcurrent relays are, and , hence , are much less affected by changes in generating capacity and in system configuration. This is because, distance relays achieve selectivity on the basis of impedance rather than current.THE CHOICE BETWEEN IMPEDANCE, REACTANCE, OR MHOBecause ground resistance can be so variable, a ground distance relay must be practically unaffected by large variations in fault resistance. Consequently, reactance relays are generally preferred for ground relaying.For phase-fault relaying, each type has certain advantages and disadvantages. For very short line sections, the reactance type is preferred for the reason that more of theline can be protected at high speed. This is because the reactance relay is practically unaffected by arc resistance which may be large compared with the line impedance, as described elsewhere in this chapter. On the other hand, reactance-type distance relays at certain locations in a system are the most likely to operate undesirably on severe synchronizing-power surges unless additional relay equipment is provided to prevent such operation.The mho type is best suited for phase-fault relaying for longer lines, and particularly where severe synchronizing-power surges may occur. It is the least likely to require additional equipment to prevent tripping on synchronizing-power surges. When mho relaying is adjusted to protect any given line section, its operating characteristic encloses the least space on the R-X diagram, which means that it will be least affected by abnormal system conditions other than line faults; in other words, it is the most selective of all distance relays. Because the mho relay is affected by arc resistance more than any other type, it is applied to longer lines. The fact that it combines both the directional and the distance-measuring functions in one unit with one contact makes it very reliable.The impedance relay is better suited for phase-fault relaying for lines of moderate length than for either very short or very long lines. Arcs affect an impedance relay more than a reactance relay but less than a mho relay. Synchronizing-power surges affect an impedance relay less than a reactance relay but more than a mho relay. If an impedance-relay characteristic is offset, so as to make it a modified• relay, it can be made to resemble either a reactance relay or a mho relay but it will always require a separate directional unit.There is no sharp dividing line between areas of application where one or another type of distance relay is best suited. Actually, there is much overlapping of these areas. Also, changes that are made in systems, such as the addition of terminals to a line, can change the type of relay best suited to a particular location. Consequently, to realizethe fullest capabilities of distance relaying, one should use the type best suited for each application. In some cases much better selectivity can be obtained between relays of the same type, but, if relays are used that are best suited to each line, different types on adjacent lines have no appreciable adverse effect on selectivity. THE ADJUSTMENT OF DISTANCE RELAYSPhase distance relays are adjusted on the basis of the positive-phase-sequence impedance between the relay location and the fault location beyond which operation of a given relay unit should stop. Ground distance relays are adjusted in the same way, although some types may respond to the zero-phase-sequence impedance. This impedance, or the corresponding distance, is called the "reach" of the relay or unit. For purposes of rough approximation, it is customary to assume an average positive-phase-sequence-reactance value of about 0.8 ohm per mile for open transmission-line construction, and to neglect resistance. Accurate data are available in textbooks devoted to power-system analysis.To convert primary impedance to a secondary value for use in adjusting a phase or ground distance relay, the following formula is used:where the CT ratio is the ratio of the high-voltage phase current to the relay phase current, and the VT ratio is the ratio of the high-voltage phase-to-phase voltage to the relay phase-to-phase voltage–all under balanced three-phase conditions. Thus, for a 50-mile, 138-kv line with 600/5 wye-connected CT’s, the secondary positive-phase-sequence reactance is aboutIt is the practice to adjust the first, or high-speed, zone of distance relays to reach to80% to 90% of the length of a two-ended line or to 80% to 90% of the distance to the nearest terminal of a multiterminal line. There is no time-delay adjustment for this unit.The principal purpose of the second-zone unit of a distance relay is to provide protection for the rest of the line beyond the reach of the first-zone unit. It should be adjusted so that it will be able to operate even for arcing faults at the end of the line. To do this, the unit must reach beyond the end of the line. Even if arcing faults did not have to be considered, one would have to take into account an underreaching tendency because of the effect of intermediate current sources, and of errors in: (1) the data on which adjustments are based, (2) the current and voltage transformers, and (3) the relays. It is customary to try to have the second-zone unit reach to at least 20% of an adjoining line section; the farther this can be extended into the adjoining line section, the more leeway is allowed in the reach of the third-zone unit of the next line-section back that must be selective with this second-zone unit.The maximum value of the second-zone reach also has a limit. Under conditions of maximum overreach, the second-zone reach should be short enough to be selective with the second-zone units of distance relays on the shortest adjoining line sections, as illustrated in Fig. 1. Transient overreach need not be considered with relays having a high ratio of reset to pickup because the transient that causes overreach will have expired before the second-zone tripping time. However, if the ratio of reset to pickup is low, the second-zone unit must be set either (1) with a reach short enough so that its overreach will not extend beyond the reach of the first-zone unit of the adjoining linesection under the same conditions, or (2) with a time delay long enough to be selective with the second-zone time of the adjoining section, as shown in Fig. 2. In this connection, any underreaching tendencies of the relays on the adjoining line sections must be taken into account. When an adjoining line is so short that it is impossible to get the required selectivity on the basis of react, it becomes necessary to increase the time delay, as illustrated in Fig. 2. Otherwise, the time delay of the second-zone unit should be long enough to provide selectivity with the slowest of (1) bus-differential relays of the bus at the other end of the line(2)transformer-differential relays of transformers on the bus at the other end of the line,or (3) line relays of adjoining line sections. The interrupting time of the circuit breakers of these various elements will also affect the second-zone time. This second-zone time is normally about 0.2 second to 0.5 second.The third-zone unit provides back-up protection for faults in adjoining line sections.So far as possible, its reach should extend beyond the end of the longest adjoining line section under the conditions that cause the maximum amount of underreach, namely, arcs and intermediate current sources. Figure 3 shows a normal back-up characteristic. The third-zone time delay is usually about 0.4 second to 1.0 second. To reach beyond the end of a long adjoining line and still be selective with the relays of a short line, it may be necessary to get this selectivity with additional time delay, as in Fig. 4.THE EFFECT OF ARCS ON DISTANCE-RELAY OPERATIONThe critical arc location is just short of the point on a line at which a distance relay's operation changes from high-speed to intermediate time or from intermediate time to back-up time. We are concerned with the possibility that an arc within the high-speed zone will make the relay operate in intermediate time, that an arc within the intermediate zone will make the relay operate in back-up time, or that an arc within the back-up zone will prevent relay operation completely. In other words, the effect of an arc may be to cause a distance relay to underreach.For an arc just short of the end of the first- or high-speed zone, it is the initial characteristic of the arc that concerns us. A distance relay's first-zone unit is so fast that, if the impedance is such that the unit can operate immediately when the arc is struck, it will do so before the arc can stretch appreciably and thereby increase itsresistance. Therefore, we can calculate the arc characteristic for a length equal to the distance between conductors for phase-to-phase faults, or across an insulator string for phase-to-ground faults. On the other hand, for arcs in the intermediate-time or back-up zones, the effect of wind stretching the arc should be considered, and then the operating time for which the relay is adjusted has an important bearing on the outcome.Tending to offset the longer time an arc has to stretch in the wind when it is in the intermediate or back-up zones is the fact that, the farther an arcing fault is from a relay, the less will its effect be on the relay's operation. In other words, the more line impedance there is between the relay and the fault, the less change there will be in the total impedance when the arc resistance is added. On the other hand, the farther away an arc is, the higher its apparent resistance will be because the current contribution from the relay end of the line will be smaller, as considered later.A small reduction in the high-speed-zone reach because of an arc is objectionable, but it can be tolerated if necessary. One can always use a reactance-type or modified-impendance type distance relay to minimize such reduction. The intermediate-zone reach must not be reduced by an arc to the point at which relays of the next line back will not be selective; of course, they too will be affected by the arc, but not so much. Reactance-type or modified-impendance-type distance relays are useful here also for assuring the minimum reduction in second-zone reach. Figure 5 shows how an impedance or mho characteristic can be offset to minimize its susceptibility to an arc. One can also help the situation by making the second-zone reach as long as possible so that a certain amount of reach reduction by an arc is permissible. Conventional relays do not use the reactance unit for the back-up zone; instead, they use either an impedance unit, a modified-impendance unit, or a mho unit. If failure of the back-up unit to operate because of an arc extended by the wind is a problem, the modified-impendance unit can be used or the mho–or "starting"–unitcharacteristic can also be shifted to make its operation less affected by arc resistance. The low-reset characteristic of some types of distance relay is advantageous in preventing reset as the wind stretches out an arc.Although an arc itself is practically all resistance, it may have a capacitive-reactance or an inductive-reactance component when viewed from the end of a line where the relays are. The impedance of an arc (ZA) has the appearance:where I1 = the complex expression for the current flowing into the arc from the end of the line where the relays under consideration are.I2= the complex expression for the current flowing into the arc from the other end of the line.R A = the arc resistance with current (I1 + I2) flowing into it.Of more practical significance is the fact that, as shown by the equation, the arc resistance will appear to be higher than it actually is, and it may be very much higher. After the other end of the line trips, the arc resistance will be higher because the arccurrent will be lower. However, its appearance to the relays will no longer be magnified, because I2 will be zero. Whether its resistance will appear to the relays to be higher or lower than before will depend on the relative and actual magnitudes of the currents before and after the distant breaker opens.输电线路的距离保护在过电流保护灵敏度低或选择性差时，应当考虑采用距离保护。
电力系统继电保护毕业论文中英文资料外文翻译文献
电力系统继电保护论文中英文资料Relay protection development present situation[Abstract ]reviewed our country electrical power system relay protection technological devil orpiment process，has outlined the microcomputer relay protection technology achievement, pro posed the future relay protection technological development tendency will be: Computerizes, n networked，protects, the control，the survey，the data communication integration and the artificial I intellectualization.[Key word ］relay protection present situation development，relay protections future development1 relay protection development present situationThe electrical power system rapid development to the relay protection proposed unceasingly t he new request，the electronic technology，computer technology and the communication rapid development unceasingly has poured into the new vigor for the relay protection technology de velopment，therefore，the relay protection technology is advantageous, has completed the deve lopment 4 historical stage in more than 40 years time。
外文翻译及文献：电力系统The
Minimum Pow er SystemA minimum electric pow er system is show n in Fig. 1. the system cons ists of an energy source, a prime mover, a g enerator, and a load.The energy source may be coal, gas, or oil burned in a furnace to heat w ater and generate steam in a boiler; it m ay be fissionable mater ial w hich, in a nuclear reactor, w ill heat w ater to produce steam; it may be w ater in a pond at an elevation above the generating station; or it may be oil or gas burned in an internal combust ion engine.Fig. 1. The minimum electric pow er systemThe prime mover may be a steam-driven turbine, a hydraulic turbine or w ater wheel, or an internal combustion engi ne. E ach one of these prime movers has the ability to convert energy in the form of heat, falling w ater, or fuel into rotation of a shaft, w hich in turn w ill drive the generator.The electrical load on the generator may be lights, motors, heaters, or other devices, alone or in combination. P rob ably the load w ill vary from minute to minute as different demands occur.The control system functions to keep the speed of the machines substantially constant and the voltage w ithin prescr ibed limits, even though the load may change. To meet these load conditions, it is necessary for fuel input to chan ge, for the prime mover input to vary, and for the torque on the shaft from the pr ime mover to the generator to ch ange in order that the generator may be kept at constant speed. In addition, the field current to the generator must be adjusted to maintain constant output voltage. The control system may include a man stationed in the pow er pla nt that w atches a set of meters on the generator-output ter minals and makes the necessary adjustments manually. 3In a modem station, the control system is a servomechanis m that senses a generator-output conditions and autom atically makes the necessary changes in energy input and field current to hold the electrical output w it hin certain specifications.More Complicated SystemsIn most situations the load is not directly connected to the generator ter minals. More commonly the load is some di stance from the generator, requir ing a pow er line connecting them. It is desirable to keep the electric pow er supply at the load w ithin specifications. How ever, the controls are near the generator, w hich may be in another building, p erhaps several miles aw ay.If the distance from the generator to the load is considerable, it may be desir able to install transformers at the gen erator and at the load end, and to trans mit the pow er over a high-voltage line (Fig. 2). For the same pow er, the hi gher-voltage line carries less current, has low er losses for the same w ire size, and provides more stable v oltage.In some cases an overhead line may be unacceptable. Instead it may be advantageous to use an under ground ca ble. With the pow er systems talked above, the pow er supply to the load must be interrupted if, for any reason, any component of the system must be removed from service for maintenance or repair..Fig 2A generators connected through transfor mers and a high-voltage line to a distant loadAdditional system load may requir e more pow er than the generator can supply. Another generator w ith its associate d transformers and high-voltage line might be added.It can be show n that there are some advantages in making ties betw een the generators (1) and at the ends of the high-voltage lines (2and 3), as show n in Fig. 3. This system w ill operate satisfactorily as long as no trouble develo ps or no equipment needs to be taken out of service.The above system may be vastly improved by the introduction of circuit br eakers, w hich may be opened and closed as needed. Circuit breakers added to the system, Fig. 4, per mit selected piece of equipment to sw itch out of servi ce w ithout disturbing the remainder of system. With this arrangement any element of the system may be r eenergize d for maintenance or repair by oper ation of circuit breakers. Of course, if any piece of equipment is taken out of s ervice, the total load must then carried by the remaining equipment. Attention must be given to avoid over loads dur i ng such circumstances. If possible, outages of equipment are scheduled at times w hen load requirements are below nor mal.Fig. 1-3 A system w ith parallel oper ation of the generators, of the transformers and of the trans mission linesFig. 4A system w ith necessary circuit breakersFig. 5Three generators supplying three loads over high-voltage trans mission linesFig. 5 show s a system in w hich three generators and three loads are tied together by three trans mission lines. No circuit breakers are show n in this diagram, although many w ould be required in such a system.Typical System LayoutThe gener ators, lines, and other equipment w hich form an electric system are arranged depending on the manner in w hich load grow s in the area and may be rearranged from time to time.Fig. 6 A radial pow er system supply ing several loadsHow ever, there are certain plans in to w hich a particular system des ign may be classified. Three types are illustrate d: the radial system, the loop system, and the netw ork system. All of these are show n w ithout the necessary circuit breakers. In each of these systems, a single generator serves four loads.The radial system is show n in Fig. 6. Here the lines form a “tree” spreading out from the generator. Opening any li ne results in interruption of pow er to one or more of the loads.The loop system is illustrated in Fig. 7. With this arrangement all loads may be served even though one line sectio n is removed from service. In some instances dur ing nor mal operation, the loop may be open at some point, such as A. In case a line section is to be taken out, the loop is first closed at A and then the line section removed. In this manner no service interruptions occur.Fig. 1-7A loop arrangement of lines for supplying several loadsFig. 8 show s the same loads being served by a netw ork. With this arrangement each load has tw o or more circuits over w hich it is fed.Distribution circuits are commonly des igned so that they may be classified as radial or loop circuits. The high-voltag e trans mission lines of most pow er systems are arranged as netw orks. The interconnection of major pow er systems results in netw orks made up many line sections.Fig. 8A netw ork of lines for supplying several loadsAuxiliary E quipmentCircuit breakers are necessary to deenergize equipment either for normal operation or on the occurrence of short ci rcuits. Circuit breakers must be designed to carry nor mal-load currents continuously, to w ithstand the extremely high currents that occur during faults, and to separate contacts and clear a circuit in the presence of fault. Circuit break ers are rated in ter ms of these duties.When a circuit breaker opens to deenergize a piece of equipment, one side of the circuit breaker usually rem ains e nergized, as it is connected to operating equipment. Since it is sometimes necessary to w ork on the circuit breaker itself, it is also necessary to have means by w hich the circuit breaker may be completely disconnected from other energized equipment. For this purpose disconnect sw itches are placed in series w ith the circuit breakers. By openin g these disconnests, the circuit breaker may be completely deenergized, per mitting w ork to be carried on in safety.Various instruments are necessary to monitor the operation of the electr ic pow er system. Usually each generator, ea ch transformer bank, and each line has its ow n set of instruments, frequently consisting of voltmeters, ammeters, w attmeters, and var meters.When a fault occurs on a system, conditions on the system undergo a sudden change. Voltages usually drop and currents increase. These changes are most noticeable in the immediate vicinity of fault. On-line analog computers, c ommonly called relays monitor these changes of conditions, make a deter minat ion of w hich breaker should be open ed to clear the fault, and energize the trip circuits of those appropriate breakers. 'With modern equipment, the relay action and breaker opening causes removal of fault w ithin three or four cycles after its initiation.The instruments that show circuit conditions and the relays that protect the circuits are not mounted directly on the pow er lines but are placed on sw itchboards in a control house. Instrument transformers are installed on the high-vol tage equipment, by means of which it is possible to pass on to the meters and relays representative samples of th e conditions on the operating equipment. The primary of a potential transformer is connected directly to the high-vol tage equipment. The secondary provides for the instruments and relays a voltage w hich is a constant fraction of vol tage on the operating equipment and is in phase w ith it. Similarly, a current transformer is connected w ith its primar y in the high-voltage circuit. The secondary w inding provides a current w hich is a know n fraction of the pow er-equip ment current and is in phase w ith it.Bushing potential devices and capac itor potential devices serve the same purpose as potential transformers but usually w ith less accuracy in regard to ratio and phase angle.Faults on Pow er SystemsFaults and its DamageEach year new designs of pow er equipment bring about increased reliability of operation. Nevertheless, equipment f ailures and interference by outside sources occasionally result in faults on electric pow er syst ems. On the occurrenc e of a fault, current and voltage conditions become abnor mal, the delivery of pow er from the generating stations to the loads may be unsatisfactory over a considerable area, and if the faulted equipment is not promptly disconnected from the remainder of the system, damage may result to other pieces of operating equipment.A fault is the unintentional or intentional connecting together of tw o or more conductors w hich ordinarily operate w it h a difference of potential betw een them. The connection betw een the conductors may be by physical metallic cont act or it may be through an arc. At the fault, the voltage betw een the tw o parts is reduced to zero in the case of metal-to-metal contacts, or to a very low value in case the connection is through an arc. Currents of abnor mally hig h magnitude flow through the netw ork to the point of fault. These short-circuit currents w ill usually be much greater than the designed ther mal ability of the conductors in the lines or machines feeding the fault. The resultant rise in t emperature may cause damage by the annealing of conductors and by the charring of insulation. In the period duri ng w hich the fault is per mitted to exist, the voltage on the system in the near vicinity of the fault w ill be so low th at utilization equipment w ill be inoperative. It is apparent that the pow er system designer must anticipate points at which faults may occur, be able to calculate conditions that exist during a fault, and provide equipment properly adj usted to open the sw itches necessary to disconnect the faulted equipment from the remainder of the system1. Ordi narily it is desirable that no other sw itches on the system are opened, as such behavior w ould result in unnecessar y modification of the system circuits.OverloadA distinction must be made betw een a fault and an overload. An overload implies only that loads greater than the designed values have been imposed on system. Under such a circumstance the voltage at the overload point may be low, but not zero. This under voltage condition may extend for some distance beyond the overload point into the remainder of the system. The currents in the overloaded equipment are high and may exceed the ther mal des ign l imits. Nevertheless, such currents are substantially low er than in the case of a fault. Service frequently may be mai ntained, but at below-standard voltage.Overloads are rather common occurrences in homes. For example, a housew ife might plug five w affle irons into the kitchen circuit during a neighborhood party. Such an overlo ad, if per mitted to continue, w ould cause heating of the w ires from the pow er center and might eventually start a fire. To prevent such trouble, residential circuits are prote cted by fuses or circuit breakers w hich open quickly w hen currents above specified values persist. Distribution transf or mers are sometimes overloaded as customers install more and more appliances. The continuous monitoring of dist ribution circuits is necessary to be certain that transfor mer sizes are increased as load grow s.Various FaultsFaults of many types and causes may appear on electric pow er systems. Many of us in our homes have seen fray ed lamp cords w hich permitted the tw o conductors of the cord to come in contact w ith each other. When this occur s, there is a resulting flash, and if breaker or fuse equipment functions properly, the circuit is opened.Overhead lines, for the most part, are constructed of bare conductors. These are sometimes accidentally brought to gether by action of w ind, sleet, trees, cranes, airplanes, or dama ge to supporting structures. Over voltages due to li ghtning or sw itching may cause flashover of supporting or from conductor to conductor. Contamination on insulators sometimes results in flashover even dur ing nor mal voltage conditions.The conductors of underground cables are separated from each other and from ground by solid insulation, w hich m ay be oil-impregnated paper or a plastic such as polyethylene. These materials undergo some deter ioration w ith ag e, particularly if overloads on the cables have resulted in their operation at elevated temperature. Any small void pr esent in the body of the insulating material w ill result in ionization of the gas contained therein, the products of w hi ch react unfavorably w ith the insulation, deterior ation of the insulation may result in failur e of the material to retain i ts insulating properties, and short circuits w ill develop betw een the cable conductors. The possibility of cable failure is increased if lightning or sw itching produces transient voltage of abnor mally high values betw een the conductors.Transfor mer failures may be the result of insulation deterioration combined w ith over-voltages due to lightning or sw i tching trans ients. Short circuits due to insulation failure betw een adjacent turns of the same w inding may result from suddenly applied over voltages. Major insulation may fail, per mitting arcs to be established betw een primary and se condary w indings or betw een a w inding and grounded metal part such as the core or tank.Generators may fail due to breakdow n of the insulation betw een adjacent turns in the same slot, resulting in a shor t circuit in a single turn of the generator. Insulation breakdow n may also occur betw een one of the w indings and th e grounded steel structure in w hich the coils are embedded. Breakdow n betw een different w indings lying in the sam e slot results in short-circuiting extensive sections of machine.Balanced three- phase faults, like balanced three-phase loads, may be handled on a line to-neutr al bas is or on an equivalent single-phase basis. P roblems may be solved either in ter ms of volts, amperes, and ohms. The handling of faults on single-phase lines is of course identical to the method of handling three-phase faults on an equivalent s ingle-phase basis.Per manent Faults and Temporary FaultsFaults may be classified as per manent or temporary. P er manent faults are those in w hich insulation failure or struct ure failure produces damage that makes operation of the equipment impossible and requires repairs to be made. T emporary faults are those w hich may be removed by deenergiz ing the equipment for a short period of time, short ci rcuits on overhead lines frequently are of this nature. High w inds may cause tw o or more conductors to sw ing toget her momentar ily. During the short period of contact, an arc is formed w hich may continue as long as the line remai ns energized. How ever i f automatic equipment can be brought into operation to deenergize the line quickly, little ph ysical damage may result and the line may be restored to service as soon as the are is extinguished. Arcs across insulators due to over voltages from lightning or sw itching trans ients usually can be cleared by automatic circuit-brea ker operation before significant structure damage occurs.Because of this characteristic of faults on lines, many companies operate follow ing a procedure know n as high-spee d reclosing. On the occurrence of a fault, the line is promptly deenergized by opening the circuit breakers at each end of the line. The breakers remain open long enough for the arc to clear, and then reclose automatically. In man y instances service is restored in a fraction of a second. Of course, if structure damage has occurred and the fault persists,it is necessary for the breakers to reopen and lock open.电力系统最低限度的电力系统最低电力系统显示图.1 .该系统包括能源，主要动力，一台发电机和负荷。
(完整版)电力系统外文英语文献资料
Electric Power SystemElectrical power system refers to remove power and electric parts of the part,It includes substation, power station and distribution. The role of the power grid is connected power plants and users and with the minimum transmission and distribution network disturbance through transport power, with the highest efficiency and possibility will voltage and frequency of the power transmission to the user fixed .Grid can be divided into several levels based on the operating voltage transmission system, substructure, transmission system and distribution system, the highest level of voltage transmission system is ZhuWangJia or considered the high power grids. From the two aspects of function and operation, power can be roughly divided into two parts, the transmission system and substation. The farthest from the maximum output power and the power of the highest voltage grade usually through line to load. Secondary transmission usually refers to the transmission and distribution system is that part of the middle. If a plant is located in or near the load, it might have no power. It will be direct access to secondary transmission and distribution system. Secondary transmission system voltage grade transmission and distribution system between voltage level. Some systems only single second transmission voltage, but usually more than one. Distribution system is part of the power system and its retail service to users, commercial users and residents of some small industrial users. It is to maintain and in the correct voltage power to users responsible. In most of the system, Distribution system accounts for 35% of the total investment system President to 45%, and total loss of system of the half .More than 220kv voltage are usually referred to as Ultra high pressure, over 800kv called high pressure, ultra high voltage and high pressure have important advantages, For example, each route high capacity, reduce the power needed for the number of transmission. In as high voltage to transmission in order to save a conductor material seem desirable, however, must be aware that high voltage transmission can lead to transformer, switch equipment and other instruments of spending increases, so, for the voltage transmission to have certain restriction, allows it to specific circumstances in economic use. Although at present, power transmission most is through the exchange of HVDC transmission, and the growing interest in, mercury arc rectifier and brake flow pipe into the ac power generation and distribution that change for the high voltage dc transmission possible.Compared with the high-voltage dc high-voltage ac transmission has the following some advantages: (1) the communication with high energy; (2) substation of simple maintenance and communication cost is low; (3) ac voltage can easily and effectively raise or lower, it makes the power transmission and high pressure With safety voltage distributionHVDC transmission and high-voltage ac transmission has the following advantages: (1) it only need two phase conductors and ac transmission to three-phase conductors; (2) in the dc transmission impedance, no RongKang, phase shift and impact overvoltage; (3) due to the same load impedance, no dc voltage, and transfer of the transmission line voltage drop less communication lines, and for this reason dc transmission line voltage regulator has better properties; (4) in dc system without skin effect. Therefore, the entire section of route conductors are using; (5) for the same work, dc voltage potential stress than insulation. Therefore dc Wire need less insulation; (6) dc transmission line loss, corona to little interference lines of communication; (7) HVDC transmission without loss of dielectric, especially in cable transmission; (8) in dc system without stability and synchronization of trouble.A transmission and the second transmission lines terminated in substation or distribution substations, the substation and distribution substations, the equipment including power and instrument transformer and lightning arrester, with circuit breaker, isolating switch, capacitor set, bus and a substation control equipment, with relays for the control room of the equipment. Some of the equipment may include more transformer substations and some less, depending on their role in the operation. Some of the substation is manual and other is automatic. Power distribution system through the distribution substations. Some of them by many large capacity transformer feeders, large area to other minor power transformer capacity, only a near load control, sometimes only a doubly-fed wire feeders (single single variable substation)Now for economic concerns, three-phase three-wire type communication network is widely used, however, the power distribution, four lines using three-phase ac networks.Coal-fired power means of main power generating drive generators, if coal energy is used to produce is pushing the impeller, then generate steam force is called the fire. Use coal produces steam to promote the rotating impeller machine plant called coal-fired power plants. In the combustion process, the energy stored in the coal to heat released,then the energy can be transformed into the form within vapor. Steam into the impeller machine work transformed into electrical energy.Coal-fired power plants could fuel coal, oil and natural gas is. In coal-fired power plant, coal and coal into small pieces first through the break fast, and then put out. The coal conveyer from coal unloader point to crush, then break from coal, coal room to pile and thence to power. In most installations, according to the needs of coal is, Smash the coal storage place, no coal is through the adjustable coal to supply coal, the broken pieces of coal is according to the load changes to control needs. Through the broken into the chamber, the coal dust was in the second wind need enough air to ensure coal burning.In function, impeller machine is used to high temperature and high pressure steam energy into kinetic energy through the rotation, spin and convert electricity generator. Steam through and through a series of impeller machine parts, each of which consists of a set of stable blade, called the pipe mouth parts, even in the rotor blades of mobile Li called. In the mouth parts (channel by tube nozzle, the steam is accelerating formation) to high speed, and the fight in Li kinetic energy is transformed into the shaft. In fact, most of the steam generator is used for air is, there is spread into depression, steam turbine of low-pressure steam from the coagulation turbine, steam into the condenses into water, and finally the condensate water is to implement and circulation.In order to continuous cycle, these must be uninterrupted supply: (1) fuel; (2) the air (oxygen) to the fuel gas burning in the configuration is a must; (3) and condenser, condensed from the condensed water supply, sea and river to lake. Common cooling tower; (4) since water vapour in some places in circulation, will damage process of plenty Clean the supply.The steam power plant auxiliary system is running. For a thermal power plant, the main auxiliary system including water system, burning gas and exhaust systems, condensation system and fuel system. The main auxiliary system running in the water pump, condensation and booster pump, coal-fired power plants in the mill equipment. Other power plant auxiliary equipment including air compressors, water and cooling water system, lighting and heating systems, coal processing system. Auxiliary equipment operation is driven by motor, use some big output by mechanical drive pump and some of the impeller blades, machine drive out from the main use of water vaporimpeller machine. In coal-fired power plant auxiliary equipment, water supply pump and induced draft fan is the biggest need horsepower.Most of the auxiliary power generating unit volume increased significantly in recent years, the reason is required to reduce environment pollution equipment. Air quality control equipment, such as electrostatic precipitator, dust collection of flue gas desulfurization, often used in dust in the new coal-fired power plants, and in many already built in power plant, the natural drive or mechanical drive, fountain, cooling tower in a lake or cooling canal has been applied in coal-fired power plants and plants, where the heat release need to assist cooling system.In coal-fired power stations, some device is used to increase the thermal energy, they are (1) economizer and air preheater, they can reduce the heat loss; (2) water heater, he can increase the temperature of water into boiling water heaters; (3) they can increase and filter the thermal impeller.Coal-fired power plants usually requires a lot of coal and coal reservoirs, however the fuel system in power plant fuel handling equipment is very simple, and almost no fuel oil plants.The gas turbine power plants use gas turbine, where work is burning gas fluid. Although the gas turbine must burn more expensive oil or gas, but their low cost and time is short, and can quickly start, they are very applicable load power plant. The gas turbine burn gas can achieve 538 degrees Celsius in the condensing turbine, however, the temperature is lower, if gas turbine and condenser machine, can produce high thermal efficiency. In gas turbine turbine a combined cycle power plant. The gas through a gas turbine, steam generator heat recovery in there were used to generate vapor heat consumption. Water vapor and then through a heated turbine. Usually a steam turbine, and one to four gas turbine power plant, it must be rated output power.。
电力专业英语英文文献翻译报告
电力专业英语英文文献翻译报告Page 1.The Production of Electrical Energy(电能生产)1 English textFrom reference 1Should the generation be not adequate to balance the load demand, it is imperative that one of following alternatives be considered for keeping the system in operating condition:1. Staring fast peaking units,2. Load shedding for unimportant loads,3. generation rescheduling.It is apparent from the above that since the voltage specifications are not stringent, load frequency control is by far the most important in power system control.In order to understand the frequency control, consider a small step-increase in load. The initial distribution of the load increment is determined by the system simpedance; and the sistantaneous relative generator rotor positions. The energy required to supply the load increment is drawn from the kinetic energy of rotating machines. As a result, the system frequency drops. The distribution of load during this period among the various machines is determined by the inertias of the rotors of the generators partaking in process. This problem is stability analysis of the system.After the speed or frequency fall due to reduction in stored energy in the rotors has taken place, the drop is sensed by the governors and they divide the load increment between the machines as determined by the droops of the respective governor characterstics. Subsequently, secondary control restores the system frequency to its normal value by readjustingthe governor characteristics. Keywords：load frequency control From reference 2Modern power systems are so large that it is impossible to design a single central control system that would handle the overall control job. It is extremely useful take into account the weak links in the system and then apply control through decomposition. The demarcation of load frequency control and Mavar voltage control characteristics is one such decomposition. Geographical and functional decomposition are successfully applied to power systems and this leads to the concept of area control.A modern power system can be divided into several areas for load frequency control. Each control area fulfils the following:1.The area is a geographically contious portion of a large interconnected area, which adjusts its own generation to accommodate load changes within its precincts.2.Under normal conditions of operation, it changes bulk power with neighboring areas.3.Under abnormal conditions of operation, it may deviate from predetermined schedules and provide assistance to any neighboring control area in the system.4.It is expected, in addition, to partake with the other areas in the system in a suitable manner in the system frequency regulation.The rotors of all generators in a control area swing together for load change. Thus, a coherent group of generators within a geographical region may constitute a control area which is connected to other similar areas by weak tie lines.Keywords：areas load frequency controlFrom reference 3For plant loading schedules in thermal systems, load prediction up to two hours in advance is necessary while for unit commitment schedules prediction up to 24 hours is sufficient. Also, at all sations and control centers, short-time prediction is needed for storage and display of advance information. Based on this information, predictive security assessment of the system is made. This also helps to contain the rates of change of generator outputs within their permissible limits.For the implementation of economic scheduling of generation using digital computers, detailed estimates of the future load demands are essential in order to allow sufficient time for the calculation and implementation of the generator schedules. Whatever method is envisaged for the calculation of such economic schedules consistent with the security and spare requirements of the system, the schedules should be calculated every 15 or 30 minutes and each economic schedule should be a predictive one ,for at least about 30 minutes ahead of event. It is then obvious that the predictions are to be revised frequently in the light of any fresh information so as to minimize the estimation errors.Peak load demand forecasts are useful in determining the investment required for additional generating and transmission capacities required. Forecasts for planning require data extending over several previous years. Meaningful forecasts can be obtained with lead time of 3 to 5 years.Keywords：load predictionFrom reference 4In this method, the load is separated into two main components. The first component is a base load which is of fixed value and the second a variable component which is a functionof the weather conditions.Estimates can be made 24 hours ahead, using the weather forecast. The temperature base for weighting the effect of the predicated temperature on the load is the normal, mean temperature of the month. The normal, mean temperature of the month has zero weight. Similarly the change in consumers demand due to cloudy weather may be assumed to vary in direct proportion to the degree of cloudiness. This in turn may be expressed by an illumination index with fair, clear sky corresponding to zero weight.The base load is determined from past records. Proper weighting of the elements of the weather will be attained only after several trials. The method of prediction stabilizes after this trial period. It may be noted that the base loads for week days and weekend will generally be different for any hour.Using these base loads, a load estimate based on the best available weather forecast can be made using proper weighting of meteorological factors like temperature, cloudiness, wind velocity, etc.Keywords：proper weighting of the elements of the weather2 中文翻译及分析出自文献1：万一发电量不足以平衡负荷需求，要使电力系统处于运行状态，必须考虑采取以下选择方法中的一种：1、启动快速峰荷机组2、对不重要的用户实行拉闸断电3、重新制定发电计划从上述情况来看，电压技术的要求并不严格，目前为止负荷频率控制是电力系统控制中最重要的手段。
（完整版）电力系统外文英语文献资料
（完整版）电力系统外文英语文献资料Electric Power SystemElectrical power system refers to remove power and electric parts of the part,It includes substation, power station and distribution. The role of the power grid is connected power plants and users and with the minimum transmission and distribution network disturbance through transport power, with the highest efficiency and possibility will voltage and frequency of the power transmission to the user fixed .Grid can be divided into several levels based on the operating voltage transmission system, substructure, transmission system and distribution system, the highest level of voltage transmission system is ZhuWangJia or considered the high power grids. From the two aspects of function and operation, power can be roughly divided into two parts, the transmission system and substation. The farthest from the maximum output power and the power of the highest voltage grade usually through line to load. Secondary transmission usually refers to the transmission and distribution system is that part of the middle. If a plant is located in or near the load, it might have no power. It will be direct access to secondary transmission and distribution system. Secondary transmission system voltage grade transmission and distribution system between voltage level. Some systems only single second transmission voltage, but usually more than one. Distribution system is part of the power system and its retail service to users, commercial users and residents of some small industrial users. It is to maintain and in the correct voltage power to users responsible. In most of the system, Distribution system accounts for 35% of the total investment system President to 45%, andtotal loss of system of the half .More than 220kv voltage are usually referred to as Ultra high pressure, over 800kv called high pressure, ultra high voltage and high pressure have important advantages, For example, each route high capacity, reduce the power needed for the number of transmission. In as high voltage to transmission in order to save a conductor material seem desirable, however, must be aware that high voltage transmission can lead to transformer, switch equipment and other instruments of spending increases, so, for the voltage transmission to have certain restriction, allows it to specific circumstances in economic use. Although at present, power transmission most is through the exchange of HVDC transmission, and the growing interest in, mercury arc rectifier and brake flow pipe into the ac power generation and distribution that change for the high voltage dc transmission possible.Compared with the high-voltage dc high-voltage ac transmission has the following some advantages: (1) the communication with high energy; (2) substation of simple maintenance and communication cost is low; (3) ac voltage can easily and effectively raise or lower, it makes the power transmission and high pressure With safety voltage distribution HVDC transmission and high-voltage ac transmission has the following advantages: (1) it only need two phase conductors and ac transmission to three-phase conductors; (2) in the dc transmission impedance, no RongKang, phase shift and impact overvoltage; (3) due to the same load impedance, no dc voltage, and transfer of the transmission line voltage drop less communication lines, and for this reason dc transmission line voltage regulator has better properties; (4) in dc system withoutskin effect. Therefore, the entire section of route conductors are using; (5) for the same work, dc voltage potential stress than insulation. Therefore dc Wire need less insulation; (6) dc transmission line loss, corona to little interference lines of communication; (7) HVDC transmission without loss of dielectric, especially in cable transmission; (8) in dc system without stability and synchronization of trouble.A transmission and the second transmission lines terminated in substation or distribution substations, the substation and distribution substations, the equipment including power and instrument transformer and lightning arrester, with circuit breaker, isolating switch, capacitor set, bus and a substation control equipment, with relays for the control room of the equipment. Some of the equipment may include more transformer substations and some less, depending on their role in the operation. Some of the substation is manual and other is automatic. Power distribution system through the distribution substations. Some of them by many large capacity transformer feeders, large area to other minor power transformer capacity, only a near load control, sometimes only a doubly-fed wire feeders (single single variable substation)Now for economic concerns, three-phase three-wire type communication network is widely used, however, the power distribution, four lines using three-phase ac networks.Coal-fired power means of main power generating drive generators, if coal energy is used to produce is pushing the impeller, then generate steam force is called the fire. Use coal produces steam to promote the rotating impeller machine plant called coal-fired power plants. In the combustion process, the energy stored in the coal to heat released,then the energy can be transformed into the form within vapor. Steam into the impeller machine work transformed into electrical energy.Coal-fired power plants could fuel coal, oil and natural gas is. In coal-fired power plant, coal and coal into small pieces first through the break fast, and then put out. The coal conveyer from coal unloader point to crush, then break from coal, coal room to pile and thence to power. In most installations, according to the needs of coal is, Smash the coal storage place, no coal is through the adjustable coal to supply coal, the broken pieces of coal is according to the load changes to control needs. Through the broken into the chamber, the coal dust was in the second wind need enough air to ensure coal burning.In function, impeller machine is used to high temperature and high pressure steam energy into kinetic energy through the rotation, spin and convert electricity generator. Steam through and through a series of impeller machine parts, each of which consists of a set of stable blade, called the pipe mouth parts, even in the rotor blades of mobile Li called. In the mouth parts (channel by tube nozzle, the steam is accelerating formation) to high speed, and the fight in Li kinetic energy is transformed into the shaft. In fact, most of the steam generator is used for air is, there is spread into depression, steam turbine of low-pressure steam from the coagulation turbine, steam into the condenses into water, and finally the condensate water is to implement and circulation.In order to continuous cycle, these must be uninterrupted supply: (1) fuel; (2) the air (oxygen) to the fuel gas burning in the configuration is a must; (3) and condenser, condensed from the condensed water supply, sea and river to lake. Common coolingtower; (4) since water vapour in some places in circulation, will damage process of plenty Clean the supply.The steam power plant auxiliary system is running. For a thermal power plant, the main auxiliary system including water system, burning gas and exhaust systems, condensation system and fuel system. The main auxiliary system running in the water pump, condensation and booster pump, coal-fired power plants in the mill equipment. Other power plant auxiliary equipment including air compressors, water and cooling water system, lighting and heating systems, coal processing system. Auxiliary equipment operation is driven by motor, use some big output by mechanical drive pump and some of the impeller blades, machine drive out from the main use of water vaporimpeller machine. In coal-fired power plant auxiliary equipment, water supply pump and induced draft fan is the biggest need horsepower.Most of the auxiliary power generating unit volume increased significantly in recent years, the reason is required to reduce environment pollution equipment. Air quality control equipment, such as electrostatic precipitator, dust collection of flue gas desulfurization, often used in dust in the new coal-fired power plants, and in many already built in power plant, the natural drive or mechanical drive, fountain, cooling tower in a lake or cooling canal has been applied in coal-fired power plants and plants, where the heat release need to assist cooling system.In coal-fired power stations, some device is used to increase the thermal energy, they are (1) economizer and air preheater, they can reduce the heat loss; (2) water heater, he can increase the temperature of water into boiling water heaters; (3) they can increase and filter the thermal impeller.Coal-fired power plants usually requires a lot of coal and coal reservoirs, however the fuel system in power plant fuel handling equipment is very simple, and almost no fuel oil plants.The gas turbine power plants use gas turbine, where work is burning gas fluid. Although the gas turbine must burn more expensive oil or gas, but their low cost and time is short, and can quickly start, they are very applicable load power plant. The gas turbine burn gas can achieve 538 degrees Celsius in the condensing turbine, however, the temperature is lower, if gas turbine and condenser machine, can produce high thermal efficiency. In gas turbine turbine a combined cycle power plant. The gas through a gas turbine, steam generator heat recovery in there were used to generate vapor heat consumption. Water vapor and then through a heated turbine. Usually a steam turbine, and one to four gas turbine power plant, it must be rated output power.。
风力发电电力系统中英文对照外文翻译文献
中英文对照外文翻译(文档含英文原文和中文翻译)附件1：翻译译文风力发电对电力系统的影响摘要风力发电依赖于气象条件，并逐渐以大型风电场的形式并入电网，给电网带来各种影响。
电网并未专门设计用来接入风电，因此如果要保持现有的电力供应标准，不可避免地需要进行一些相应的调整。
讨论了在风电场并网时遇到的各种问题。
由于风力发电具有大容量、动态和随机的特性，它给电力系统的有功/无功潮流、电压、系统稳定性、电能质量、短路容量、频率和保护等方面带来影响。
针对这些问题提出了相应的解决建议和措施，以及更好利用风力发电。
关键词：风力发电；电力系统；影响；风电场1.引言人们普遍接受，可再生能源发电是未来电力的供应。
由于电力需求快速增长，对以化石燃料为基础的发电是不可持续的。
正相反，风力发电作为一种有前途的可再生能源受到了很多关注。
当由于工业的发展和在世界大部分地区的经济增长而发电的消费需求一直稳步增长时，它有减少排放和降低不可替代的燃料储备消耗的潜力。
当大型风电场（几百兆瓦）是一个主流时，风力发电越来越更受欢迎。
2006年间，世界风能装机容量从2005年的59091兆瓦达到74223兆瓦。
在2006年极大的生长表明，决策者开始重视的风能发展能够带来的好处。
由于到2020年12%的供电来于1250GW的安装风电装机，将节约累积10771000000吨二氧化碳[1]。
大型风电场的电力系统具有很高的容量，动态随机性能，这将会挑战系统的安全性和可靠性。
而提供电力系统清洁能源的同时，风农场也会带来一些对电力系统不利的因素。
风力发电的扩展和风电在电力系统的比重增加，影响将很可能成为风力集成的技术性壁垒。
因此，应该探讨其影响和提出克服这些问题的对策。
2.风力发电发展现状从全球风能委员会（GWEC）的报告中，拥有最高装机容量总数的国家是德国（20621兆瓦），西班牙（11615兆瓦），美国（11603兆瓦），印度（6270兆瓦）和丹麦（3136兆瓦）。
有关电力系统自动化中英文翻译资料
外文资料翻译Power System AutomationPower system integration is the act of communication data to, or among IED s in the I&C system and remote users. Substation integration refers to combining data from the IED′s local to a substation so that there is a s ingle point of contact in the substation for all of the I&C data. Poletop devices often communicate to the substation via wireless or fiber connections. Remote and local substation and feeder control is passed through the substation controller acting as a single point of contact. Some systems bypass the substation controller by using direct connections to the poletop devices, such as RTU s, protective relays, and controllers.Power system automation is the act of automatically controlling the power system via I&C devices. Substation automation refers to using IED data, control and automation capabilities within the substation, and control commands from remote users to control power system devices. Since true substation automation relies on substation integration, the terms are often used interchangeably.Power system automation includes processes associated with generation and delivery of power. A subset of the process deal with delivery of power at transmission and distribution levels, which is power delivery automation. Together, monitoring and control of power delivery system in the substation and on the poletop reduce the occurrence of outages and shorten the duration of outages that do occur. The IED′s, communications protocols, and communications methods described in previous sections, work together as a system to perform power system automation.Though each utility is unique, most consider power delivery automation of transmission and distribution substation and feeders to include :Supervisory Control and Data Acquisition(SCADA)-operatorsupervision and control;Distribution Automation-fault location, auto-isolation, auto-sectionalizing, and auto-restoration;Substation Automation-breaker failure, reclosing, battery monitoring, dead substation transfer, and substation load transfer;Energy Management System (EMS)-load flow, VAR and voltage monitoring and control, generation control, transformer and feeder load balancing;Fault analysis and device maintenance.System without automated control still have the advantages of remote monitoring and operator control of power system devices, which includes: Remote monitoring and control of circuit breakers and automated switches;Remote monitoring of non-automated switches and fuses;Remote monitoring and control of capacitor banks;Remote monitoring and voltage control;Remote power quality monitoring and control.IED s described in the overview are used to perform power system integration and automation. Most designs require that the one IED act as the substation controller and perform data acquisition and control of the other IED s. The substation controllers is often called upon to support system automation tasks as well. The communications industry uses the term client/server for a device that acts as a master, or client, retrieving data from some devices and then acts as a slaver, a server, sending this data to other devices. The client/server collecting and concentrating dynamically. A data concentrator creates a substation databases by collecting and concentrating dynamic data from several devices. In this fashion, essential subsets of data from each IED are forwarded to a master through one data transfer. The concentrator databases is used to pass data between IED s that are not directly connected.A substation archive client/server collects and archives data from several devices. The archive data is retrieved when it is convenient for the userto do so.The age of the IED s now in substations varies widely. Many of these IED s are still useful but lack the most recent protocols. A communications processor that can communicate with each IED via a unique baud rate and protocol extends the time that each IED is useful. Using a communications processor for substation integration also easily accommodates future IED s. It is rare for all existing IED s to be discarded during a substation integration upgrade project.The benefits of monitoring, remote control, and automation of power delivery include improved employee and public safety, and deferment of the cost of purchasing new equipment. Also, reduced operation and maintenance costs are realized through improved use of existing facilities and optimized performance of the power system through reduced losses associated with outages and improved voltage profile. Collection of information can result in better planning and system design, and increased customer satisfaction will result from improved responsiveness, service reliability, and power quality.Power system automation includes a variety of equipment. The principal items are listed and briefly described below.Instrument transformers are used to sense power system current and voltage. They are physically connected to power system apparatus and convert the actual power system signals, which includes high voltage and current magnitudes, down to lower signal levels.Transducers convert the analog output of an instrument transformer from one magnitude to another or from one value type to another, such as from an ac current to dc voltage.As the name implies, a remote terminal device, RTU, is an IED that can be installed in a remote location, and acts as a termination point for filed contacts. A dedicated pair of copper conductors are used to sense every contract and transducer value. These conductors originated at the power system device, are installed in trenches or overhead cable trays, and are then terminated on panels within the RTU. The RTU can transfer collected data to other devices andreceive data and control commands from other device through a serial port. User programmable RTUs are referred to as “smart RTUs.”A communication switch is a device that switches between several serial ports when it is told to do so. The remote user initiates communications with the port switch via a connection to the substation , typically a leased line or dial-up telephone connection. Once connected, the user can route their communication through the port switch to one of the connected substation IEDs. The port switch merely “passes through” the IED communication.A meter is an IED that is used to create accurate measurement of power system current, voltage, and power values. Metering values such as demand and peak are saved within the meter to create historical information about the activity of the power system.A digital fault recorder ,is an IED that records information about power system disturbances. It is capable of storing data in digital format when triggered by conditions detected on the power system. Harmonics, frequency, and voltage are examples of data captured by DFRs.Load tap changer are devices used to change the tap position on transformers. These devices work automatically or can be controlled via another local IED or form a remote operator or process.Recloser controllers remotely control the operation of automated reclosers and switches. These devices monitor and store power system conditions and determine when to perform control actions. They also accept commands form a remote operator or process.电力系统自动化电力系统集成是在I&C系统中的IED和远程用户之间进行数据通信的操作。
智能电网供配电系统中英文对照外文翻译文献
中英文对照资料外文翻译外文资料翻译Power supply system of high-rise building designAbstract: with the continuous development of city size, more and more high-rise buildings, therefore high-rise building electrical design to the designers had to face. In this paper, an engineering example, describes the electrical design of high-rise buildings and some of the more typical issues of universal significance, combined with the actual practice of an engineering solution to the problem described.Key words: high-rise building; electrical design; distribution; load calculation1 Project OverviewThe commercial complex project,with a total construction area of 405570m2,on the ground floor area of 272330m2, underground construction area of 133240m2, the main height of 99m. Project components are: two office buildings, construction area is 70800m2, 28 layers, the standard story is 3.2m.2 Load Calculation1) Load characteristics: electric load, much larger than the "national civil engineering technical measures" Large 120W/m2 indicators, especially in the electricity load more food, and different types of food and beverage catering different cultural backgrounds also high.2) the uncertainty of a large load, because the commercial real estate rents are often based on market demand, and constantly adjust the nature of the shops, making the load in the dynamic changes.3) There is no specification and technical measures in the different types of commercial projects refer to the detailed parameters of the shops, engineering design load calculation in the lack of data, in most cases to rely on staff with previous experience in engineering design calculations.Load the selection of parameters: for the above problems, the load calculation, the first developer of sales and good communication, to determine the form of layers of the forms and nature of floor area, which is calculated on the basis of electrical load basis; followed to determine parameter index within the unit area of shops is also very important and complex because there is no clear indicator of the specification can refer to; and different levels of economic development between cities is not balanced, power indices are also different; will be in the same city, different regions have different consumer groups .3) the need to factor in the choice: parameters determined, the need for load calculation. Need to factor commonly used method, the calculation will not repeat them. Need to explore is the need for coefficient selection, which in the current specifications, manuals and the "unified technical measures" is also not clear requirements, based on years of design experience that most end shops in the distribution or level within the household distribution box with case Kx generally take a while, in the calculation of the loop route to take 0.7 to 0.8, the distribution transformers in the substation calculations take 0.4 to 0.6.3 substations setLoad calculation based on the results of this project the total installed capacity of transformer 43400Kv.A, after repeated consultations with the power company, respectively, in the project in northern, central and southern three sections set the three buildings into three power substations, 1 # set 6 sets 2500Kv.A transformer substation, take the northern section of power supply; 2 # 4 1600Kv.A transformer substations located, plus 6 sets 2000Kv.A transformers, take the middle of the power supply, in addition to 5 Taiwan 10Kv.A high-pressure water chillers (total 4000Kv.A); 3 # substation located 2 units plus 2 units 1000Kv.A 2000Kv.A transformers, take the southern section of A, B twooffice supply. 10Kv power configuration of this project into two points, each at the two 10Kv lines, the power company under the provisions of 10Kv power capacity: maximum load per channel is about to 11000Kv.A, two is the 22000Kv.A, design # 1 , 3 # combination of a substation 10Kv, power line, with a total capacity of 21000Kv.A; 2 # substation transformers and 10Kv, 10Kv chillers sharing a power line, with a total capacity of 22400Kv.A. The design of the substation layout, in addition to meeting regulatory requirements, it also need to consider the high-pressure cabinets, transformers and low voltage power supply cabinet by order of arrangement, especially in low voltage distribution cabinet to feed the cable smooth and easy inspection duty problems are not seriously consider the construction of the cable crossing will cause more long detour, a waste of floor space, and convenient inspections and other issues【8】.4 small fire load power supplyIn the design of large commercial projects often encounter small fire load of electrical equipment and more dispersed distribution, if fed by a substation, a substation will be fed a lot of low-voltage low-current counter circuit breaking capacity circuit breaker and conductor of the dynamic and thermal stability in a certain extent. According to GB50045-1995 "fire protection design of tall buildings," rule "should be used in Fire Equipment dedicated power supply circuit, the power distribution equipment shall be provided with clear signs." Interpretation of the provisions of the power supply circuit means "from the low-voltage main distribution room (including the distribution of electrical room) to last a distribution box, and the general distribution lines should be strictly separated." In this design, the use of methods to increase the level of distribution, that is different from the substation bus segments, respectively, a fire fed a special circuit, set in place two distribution cabinets, distribution cabinets and then the resulting radial allocated to the end of the dual power to vote each box, so that not only meets the specification requirements for dedicated power supply circuit, but also to avoid feeding the substation level of many small current loop.5, the choice of circuit breaker and conductorCommercial real estate projects use the room as the uncertainty in the choice of circuit breakers and conductors must be considered in a certain margin to meet the needs caused by adjustment of the load changes. According to this characteristic, increased use in the design of the plug bus-powered, not only meet the requirements of large carrying capacity, and also allows the flexibility to increase supply and distribution, are reserved in each shaft in the plug-box backup in order to change, according to changes in upper and lower load, to adjust. For example: a bus is responsible for a shaft 1 to 3 layers of power, when a layer due to the change in capacity increases, while the 3-layer capacity is reduced, you can use a spare plug box layer off the 3-layer 1 layer capacity rationing . This level distribution in the substation, select the circuit breaker to choose the setting value when the circuit breaker to adjust to changes at the end to adjust the load setting value; in the bus and the transformer circuit breaker according to the choice of the general framework of values to select . For example: Route certain equipment capacity 530Kv, Kx take 0.7 to calculate current of 704A, select the frame circuit breaker is 1000A, tuning is 800A; current transformer for the 1000/50; bus carrying capacity for the 1000A, this road can meet the maximum 1000A current load requirements, even if there is adjustment, power distribution switches and circuit can not make big changes.6 layer distribution box setAccording to the division of layers of fire protection district, respectively numbered as A ~ K layers within the set level shaft for the retail lighting power distribution box, with one on one power supply shops in radial power. Should be noted that the forms of the complex layers of layers of fire partition, does not correspond to the lower, making some of shaft power in charge of the fire district at the same time, also responsible for the power supply adjacent to the fire district. At design time, using the principle of proximity, while also taking into account the burden of the whole trunk load conditions, so that each shaft as far as possible a more balanced load. PrerequisitesThe loop that you want to auto-tune must be in automatic mode. The loopoutput must be controlled by the execution of the PID instruction. Auto-tune will fail if the loop is in manual mode.Before initiating an auto-tune operation your process must be brought to a stable state which means that the PV has reached setpoint (or for a P type loop, a constant difference between PV and setpoint) and the output is not changing erratically.Ideally, the loop output value needs to be near the center of the control range when auto-tuning is started. The auto-tune procedure sets up an oscillation in the process by making small step changes in the loop output. If the loop output is close to either extreme of its control range, the step changes introduced in the auto-tune procedure may cause the output value to attempt to exceed the minimum or the maximum range limit.If this were to happen, it may result in the generation of an auto-tune error condition, and it will certainly result in the determination of less than near optimal suggested values.Auto-Hysteresis and Auto-DeviationThe hysteresis parameter specifies the excursion (plus or minus) from setpoint that the PV (process variable) is allowed to make without causing the relay controller to change the output. This value is used to minimize the effect of noise in the PV signal to more accurately determine the natural oscillation frequency of the process.If you select to automatically determine the hysteresis value, the PID Auto-Tuner will enter a hysteresis determination sequence. This sequence involves sampling the process variable for a period of time and then performing a standard deviation calculation on the sample results.In order to have a statistically meaningful sample, a set of at least 100 samples must be acquired. For a loop with a sample time of 200 msec, acquiring 100 samples takes 20 seconds. For loops with a longer sample time it will take longer. Even though 100 samples can be acquired in less than 20 seconds for loops with sample times less than 200 msec, the hysteresis determinationsequence always acquires samples for at least 20 seconds.Once all the samples have been acquired, the standard deviation for the sample set is calculated. The hysteresis value is defined to be two times the standard deviation. The calculated hysteresis value is written into the actual hysteresis field (AHYS) of the loop table.TipWhile the auto-hysteresis sequence is in progress, the normal PID calculation is not performed. Therefore, it is imperative that the process be in a stable state prior to initiating an auto-tune sequence. This will yield a better result for the hysteresis value and it will ensure that the process does not go out of control during the auto-hysteresis determination sequence.The deviation parameter specifies the desired peak-to-peak swing of the PV around the set point. If you select to automatically determine this value, the desired deviation of the PV is computed by multiplying the hysteresis value by 4.5. The output will be driven proportionally to induce this magnitude of oscillation in the process during auto-tuning.Auto-Tune SequenceThe auto-tuning sequence begins after the hysteresis and deviation values have been determined. The tuning process begins when the initial output step is applied to the loop output.This change in output value should cause a corresponding change in the value of the process variable. When the output change drives the PV away from setpoint far enough to exceed the hysteresis boundary a zero-crossing event is detected by the auto-tuner. Upon each zero crossing event the auto-tuner drives the output in the opposite direction.The tuner continues to sample the PV and waits for the next zero crossing event.A total of twelve zero-crossings are required to complete the sequence. The magnitude of the observed peak-to-peak PV values (peak error) and the rate at which zero-crossings occur are directly related to the dynamics of the process. Early in the auto-tuning process, the output step value is proportionally adjustedonce to induce subsequent peak-to-peak swings of the PV to more closely match the desired deviation amount. Once the adjustment is made, the new output step amount is written into the Actual Step Size field (ASTEP) of the loop table.The auto-tuning sequence will be terminated with an error, if the time between zero crossings exceeds the zero crossing watchdog interval time. The default value for the zero crossing watchdog interval time is two hours.Figure 1 shows the output and process variable behaviors during an auto-tuning sequence on a direct acting loop. The PID Tuning Control Panel was used to initiate and monitor the tuning sequence.Notice how the auto-tuner switches the output to cause the process (as evidenced by the PV value) to undergo small oscillations. The frequency and the amplitude of the PV oscillations are indicative of the process gain and natural frequency.7 public area distribution box setTaking into account the future needs of the business re-decoration of public areas must be reserved for power. Here the design needs to consider the following points:①question of how much reserve power, lighting and electricity, which according to GB50034-2004 "Architectural Lighting Design Standards" table of Article 6.1.3 and 6.1.8, commercial building lighting power density value, high-end supermarkets, business offices as 20W/m2, under the "decorative lighting included 50% of the total lighting power density calculation" requirements, using the reserved standard 40W/m2.②In order to facilitate the decoration in each partition set fire lighting in public areas and emergency lighting distribution box distribution box, in order to identify the electrical power distribution decoration cut-off point.③the staircase, storage rooms and other parts of the decoration does not need to do, set the power distribution circuit or a separate distribution box, try not to be reserved from the public area of electricity distribution board fed hardcover out.④control of lighting in public areas, the majority in two ways, namely,C-BUS control system or the BA system, the use of C-BUS has the advantage of more flexible control, each road can be fed out of control, adjustable light control; shortcomings is a higher cost. BA system control advantages of using low cost, simple control; disadvantage is that the exchanges and contacts for the three-phase, three-way control may be related both to open, or both, in the decoration of the contacts required to feed the power supply circuit diverge to avoid failure blackouts.Design of distribution box 8In the commercial real estate design, shop design is often only a meter box, and outlet route back to the needs of the user according to their second design, but the shops are difficult to resolve within the power supply fan coil units, air-conditioning system as a whole can not debug. The project approach is to add a circuit breaker in the meter box for the coil power supply, another way for users to use the second design, as shown below.User distribution box design9 distribution cabinet / box number and distribution circuitsLarge-scale projects are often low voltage distribution cabinet / box number, low-voltage circuits to feed the more often there will be cabinet / box number and line number duplication, resulting in the design and the future looks difficult maintenance and overhaul. The project has three 10Kv substations, 20 transformer, hundreds of low-voltage fed out of the closet, fed the circuit more. Accordance with the International Electrotechnical Commission (IEC) and the Chinese national standard requirements:①All the distribution number to be simple and clear, not too box and line numbers are not repeated.②number to simple and clear, not too long.③distinction between nature and type of load.④law was easy to find, make viewer at a glance. Based on the above requirements and on the ground, fire district and the underground construction industry form the different conditions, using two slightly different ways.Essential for the underground garage, uses a single comparison, also relatively fire district neat, according to fire district number, such as AL-BL-1 / 1, AP and APE, the meaning of the letters and numbers: AL on behalf of lighting distribution (AP on behalf of Power distribution box, APE on behalf of the emergency power distribution box); BI on behalf of the basement; 1 / 1 for partition 1, I fire box. Above ground is more complex, more fire district, and on the fire district does not correspond to the lower, according to shaft number is better, such as AL-1-A1, AP, and APE, letters and numbers mean: 1 represents a layer; A1 on behalf of A, No. 1 shaft fed a distribution box. Fed a low-voltage circuits, such as the number of uses: W3-6-AL-1-A1, W3-6) indicates that the route back to power supply transformer 3, 6, feed the power distribution cabinet, AL-1-A1, said the then the first loop of the distribution box for the AL-1-A1 and so on, and so on.10 ConclusionWith more and more complex commercial design projects, designers need to continually improve the design level, designed to make fine. These are only bits of the design in the business lessons learned, and the majority of designers want to communicate译文：浅谈高层建筑供配电系统设计摘要：随着城市规模的不断发展，高层建筑越来越多，因此，高层建筑电气设计就成为设计者不得不面对的问题。
电力系统继电保护中英文对照表
电力系统继电保护中英文对照表中文词汇英文词汇电力系统Power system继电保护Relay protection保护装置Protective device故障Fault故障电流Fault current故障检测Fault detection故障分类Fault classification故障定位Fault location故障记录器Fault recorder过电压保护Overvoltage protection过电流保护Overcurrent protection地电流保护Earth current protection短路Short circuit短路电流Short circuit current瞬时值Instantaneous value时限值Time limit value跳闸Tripping启动电流Starting current感应式电流互感器Inductive current transformer 压板式电流互感器Plate-type current transformer 合闸Closing开关刀闸Switch disconnector接地刀闸Ground disconnector电流互感器Current transformer功率互感器Power transformer电压互感器Voltage transformer电流差动保护Current differential protection 电压差动保护Voltage differential protection 闭锁Blocking重保Backup protection保护跳闸Protection tripping故障保护Fault protection过零保护Zero-crossing protection过频保护Over-frequency protection沉侵保护Inrush protection远方保护Remote protection就地保护Local protection瞬变保护Transient protection空气开关Air switch隔离开关Isolation switch封闭开关Enclosed switch电力系统自动化Power system automation 故障指示灯Fault indicator电源Power supply接线Wiring电流Current电压Voltage功率Power频率Frequency相位Phase直流Direct current交流Alternating current以上是电力系统继电保护中英文对照表，希望对您有所帮助。
电力系统毕业论文中英文外文文献翻译
电力系统电力系统介绍随着电力工业的增长，与用于生成和处理当今大规模电能消费的电力生产、传输、分配系统相关的经济、工程问题也随之增多。
这些系统构成了一个完整的电力系统。
应该着重提到的是生成电能的工业，它与众不同之处在于其产品应按顾客要求即需即用。
生成电的能源以煤、石油，或水库和湖泊中水的形式储存起来，以备将来所有需。
但这并不会降低用户对发电机容量的需求。
显然，对电力系统而言服务的连续性至关重要。
没有哪种服务能完全避免可能出现的失误，而系统的成本明显依赖于其稳定性。
因此，必须在稳定性与成本之间找到平衡点，而最终的选择应是负载大小、特点、可能出现中断的原因、用户要求等的综合体现。
然而，网络可靠性的增加是通过应用一定数量的生成单元和在发电站港湾各分区间以及在国内、国际电网传输线路中使用自动断路器得以实现的。
事实上大型系统包括众多的发电站和由高容量传输线路连接的负载。
这样，在不中断总体服务的前提下可以停止单个发电单元或一套输电线路的运作。
当今生成和传输电力最普遍的系统是三相系统。
相对于其他交流系统而言，它具有简便、节能的优点。
尤其是在特定导体间电压、传输功率、传输距离和线耗的情况下，三相系统所需铜或铝仅为单相系统的75%。
三相系统另一个重要优点是三相电机比单相电机效率更高。
大规模电力生产的能源有：1.从常规燃料（煤、石油或天然气）、城市废料燃烧或核燃料应用中得到的蒸汽；2.水；3.石油中的柴油动力。
其他可能的能源有太阳能、风能、潮汐能等，但没有一种超越了试点发电站阶段。
在大型蒸汽发电站中，蒸汽中的热能通过涡轮轮转换为功。
涡轮必须包括安装在轴承上并封闭于汽缸中的轴或转子。
转子由汽缸四周喷嘴喷射出的蒸汽流带动而平衡地转动。
蒸汽流撞击轴上的叶片。
中央电站采用冷凝涡轮，即蒸汽在离开涡轮后会通过一冷凝器。
冷凝器通过其导管中大量冷水的循环来达到冷凝的效果，从而提高蒸汽的膨胀率、后继效率及涡轮的输出功率。
而涡轮则直接与大型发电机相连。
供配电系统中英文对照外文翻译文献
中英文对照外文翻译文献(文档含英文原文和中文翻译)POWER SUPPLY AND DISTRIBUTION SYSTEMABSTRACTThe basic function of the electric power system is to transport the electric power towards customers. The l0kV electric distribution net is a key point that connects the power supply with the electricity using on the industry, business and daily-life. For the electric power, allcostumers expect to pay the lowest price for the highest reliability, but don't consider that it's self-contradictory in the co-existence of economy and reliable.To improve the reliability of the power supply network, we must increase the investment cost of the network construction But, if the cost that improve the reliability of the network construction, but the investment on this kind of construction would be worthless if the reducing loss is on the power-off is less than the increasing investment on improving the reliability .Thus we find out a balancepoint to make the most economic,between the investment and the loss by calculating the investment on power net and the loss brought from power-off.KEYWARDS：power supply and distribution,power distribution reliability，reactive compensation,load distributionTEXTThe revolution of electric power system has brought a new big round construction,which is pushing the greater revolution of electric power technique along with the application of new technique and advanced equipment. Especially, the combination of the information technique and electric power technique, to great ex- tent, has improved reliability on electric quality and electric supply. The technical development decreases the cost on electric construction and drives innovation of electric network. On the basis of national and internatio- nal advanced electric knowledge, the dissertation introduces the research hotspot for present electric power sy- etem as following.Firstly, This dissertation introduces the building condition of distribution automation(DA), and brings forward two typical construction modes on DA construction, integrative mode and fission mode .It emphasize the DA structure under the condition of the fission mode and presents the system configuration, the main station scheme, the feeder scheme, the optimized communication scheme etc., which is for DA research reference.Secondly, as for the (DA) trouble measurement, position, isolation and resume, This dissertation analyzes the changes of pressure and current for line problem, gets math equation by educing phase short circuit and problem position under the condition of single-phase and works out equation and several parameter s U& , s I& and e I& table on problem . It brings out optimized isolation and resume plan, realizes auto isolation and network reconstruction, reduces the power off range and time and improves the reliability of electric power supply through problem self- diagnoses and self-analysis. It also introduces software flow and use for problem judgement and sets a model on network reconstruction and computer flow.Thirdly, electricity system state is estimated to be one of the key techniques in DA realization. The dissertation recommends the resolvent of bad measurement data and structure mistake on the ground of describing state estimate way. It also advances a practical test and judging way on topology mistake in state estimate about bad data test and abnormity in state estimate as well as the problem and effect on bad data from state measure to state estimate .As for real time monitor and control problem, the dissertation introduces a new way to solve them by electricity break and exceptional analysis, and the way has been tested in Weifang DA.Fourthly, about the difficulty for building the model of load forecasting, big parameter scatter limit and something concerned, the dissertation introduces some parameters, eg. weather factor, date type and social environment effect based on analysis of routine load forecasting and means. It presents the way for electricity load forecasting founded on neural network(ANN),which has been tested it’s validity by examp le and made to be good practical effect.Fifthly, concerning the lack of concordant wave on preve nting concordant wave and non-power compensation and non-continuity on compensation, there is a topology structure of PWM main circuit and nonpower theory on active filter the waves technique and builds flat proof on the ground of Saber Designer and proves to be practical. Meanwhile, it analyzes and designs the way of non-power need of electric network tre- nds and decreasing line loss combined with DA, which have been tested its objective economic benefit throu- gh counting example.Sixthly, not only do the dissertation design a way founded on the magrginal electric price fitted to our present national electric power market with regards to future trends of electric power market in China and fair trade under the government surveillance, that is group competitio n in short-term trade under the way of grouped price and quantityharmony, but also puts forward combination arithmetic, math model of trading plan and safty economical restriction. It can solve the original contradiction between medium and long term contract price and short term competitive price with improvement on competitive percentage and cut down the unfair income difference of electric factory, at the same time, it can optimize the electric limit for all electric factories and reduce the total purchase charge of electric power from burthen curve of whole electric market network.The distribution network is an important link among the power system. Its neutral grounding mode and operation connects security and stability of the power system directly. At the same time, the problem about neutral grounding is associated with national conditions, natural environment, device fabrication and operation. For example, the activity situation of the thunder and lightning, insulating structure and the peripheral interference will influence the choice of neutral grounding mode Conversely, neutral grounding mode affects design, operation, debugs and developing. Generally in the system higher in grade in the voltage, the insulating expenses account for more sizable proportion at the total price of the equipment. It is very remarkable to bring the economic benefits by reducing the insulating level. Usually such system adopt the neutral directly grounding and adopt the autoreclosing to guarantee power supply reliability. On the contrary, the system which is lower in the voltage adopts neutral none grounding to raise power supply reliability. So it is an important subject to make use of new- type earth device to apply to the distribution network under considering the situation in such factors of various fields as power supply reliability, safety factor, over-voltage factor, the choice of relay protection, investment cost, etc.The main work of this paper is to research and choice the neutral grounding mode of the l0kV distribution network. The neutral grounding mode of the l0kV network mainly adopts none grounding, grounding by arc suppressing coil, grounding by reactance grounding and directly grounding. The best grounding mode is confirmed through the technology comparison. It can help the network run in safety and limit the earth electric arc by using auto-tracking compensate device and using the line protection with the detection of the sensitive small ground current. The paper introduces and analyzes the characteristic of all kind of grounding modes about l0kV network at first. With the comparison with technological and economy, the conclusion is drawn that the improved arc suppressing coil grounding mode shows a very big development potential.Then, this paper researches and introduces some operation characteristics of the arc suppressing coil grounding mode of the l0kV distribution network. And then the paper putemphasis on how to extinguish the earth electric arc effectively by utilizing the resonance principle. This paper combines the development of domestic and international technology and innovative achievement, and introduces the computer earth protection and autotracking compensate device. It proves that the improved arc suppressing coil grounding mode have better operation characteristics in power supply reliability, personal security, security of equipment and interference of communication. The application of the arc suppressing coil grounding mode is also researched in this paper.Finally, the paper summarizes this topic research. As a result of the domination of the arc suppressing coil grounding mode, it should be more popularized and applied in the distribution network in the future.The way of thinking, project and conclusions in this thesis have effect on the research to choose the neutral grounding mode not only in I0kV distribution network but also in other power system..The basic function of the electric power system is to transport the electric power towards customers. The l0kV electric distribution net is a key point that connects the power supply with the electricity using on the industry, business and daily-life. For the electric power, all costumers expect to pay the lowest price for the highest reliability, but don't consider that it's self-contradictory in the co-existence of economy and reliable. To improve the reliability of the power supply network, we must increase the investment cost of the network con- struction But, if the cost that improve the reliability of the network construction, but the investment on this kind of construction would be worthless if the reducing loss is on the power-off is less than the increasing investment on improving the reliability .Thus we find out a balance point to make the most economic, between the investment and the loss by calculating the investment on power net and the loss brought from power-off. The thesis analyses on the economic and the reliable of the various line modes, according to the characteristics various line modes existed in the electric distribution net in foshan..First, the thesis introduces as the different line modes in the l0kV electric distribution net and in some foreign countries. Making it clear tow to conduct analyzing on the line mode of the electric distribution net, and telling us how important and necessary that analyses are.Second, it turns to the necessity of calculating the number of optimization subsection, elaborating how it influences on the economy and reliability. Then by building up the calculation mode of the number of optimization subsection it introduces different power supply projects on the different line modes in brief. Third, it carries on the calculation andanalyses towards the reliability and economy of the different line modes of electric distribution net, describing drafts according by the calculation. Then it makes analysis and discussion on the number of optimization subsection.At last, the article make conclusion on the economy and reliability of different line modes, as well as, its application situation. Accordion to the actual circumstance, the thesis puts forward the beneficial suggestion on the programming and construction of the l0kV electric distribution net in all areas in foshan. Providing the basic theories and beneficial guideline for the programming design of the lOkV electric distribution net and building up a solid net, reasonable layout, qualified safe and efficiently-worked electric distribution net.References[1] Wencheng Su. Factories power supply [M]. Machinery Industry Publishing House. 1999.9[2] Jiecai Liu. Factories power supply design guidance [M]. Machinery Industry Publishing House.1999.12[3] Power supply and distribution system design specifications[S].China plans Press. 1996[4] Low-voltage distribution design specifications [S].China plans Press. 1996.6供配电系统摘要电力系统的基本功能是向用户输送电能。
变电站中英文资料对照外文翻译文献综述
变电站中英文资料对照外文翻译文献综述XXXns are an essential part of electrical power systems。
servingas the interface een high-voltage n lines and lower-voltage n lines。
They play a critical role in XXX homes。
businesses。
and industries.Types of nsThere are several types of ns。
including n ns。
n ns。
and customer XXX to the end-users and step down the voltage for n to XXX a single customer or group of customers.XXXns consist of us components。
including transformers。
circuit breakers。
switches。
XXX are used to step up or step down thevoltage of the electricity。
XXX are used to control the flow ofXXX to the system.XXXXXX stages。
including site n。
layout design。
equipment n。
XXX n lines。
land availability。
and environmental ns。
The layout design involves determining the placement of equipment。
XXX appropriate transformers。
circuit breakers。
and other components。
电动机控制中英文对照外文翻译文献
电动机控制中英文对照外文翻译文献(文档含英文原文和中文翻译)原文：Control of Electric winchFor motor control, we know the best way is to use the style buttons to move the many simple manual console. And this console, in some applications may still be a good choice, as some complex control headache can also be used. This article describes in your design, build or purchase winch controller, you have the motor's basic electrical equipment and you will need to address the user interface command addressed.First, the manual should be a manual control console type, so if you remove your finger buttons, hoist will stop. In addition, each control station equipped with an emergency need to brake, hoist the emergency brake to cut off all power, not just the control circuit. Think about it, if the hoist at the stop, it did not stop, you do need a way to cut off the fault line protection power. Set the table in the control of a key operated switch, is also a very good idea, especially in the line leading to theworkstation can not control, you can use the switch.(in the design of the console, even the simplest manual console, but also consider setting by specialized personnel to operate the safe operation of the keys.) Constant speed motor controlFor a fixed speed winch actual control device is a three-phase starter. Turn the motor is reversed, by a simple switch controlled phase transformation sequence from ABC to CBA. These actions are completed by two three-pole contactor-style, and they are interlocked, so that they can not be simultaneously closed. NEC, required in addition to overload and short circuit protection devices. To protect the motor against overload due to mechanical effects caused by overheating in the heat to be installed inside the starter overload delay device. When the heat overload delay device overheating, it has a long double off the metal motor power. In addition In addition, you can also select a thermistor can be installed in the motor winding way, it can be used to monitor motor temperature changes. For the short-circuit protection, we generally used by motor fuses to achieve.A linear current independent contactors, the contactors are configured should be more than the current main circuit contactor, so as to achieve the purpose of redundancy. This sets the current contactor is controlled by the security circuit, such as: emergency brake and the more-way limits.We can use the limit switches to achieve the above operation. When you reach the end of the normal travel limit position, the hoist will stop, and you can only move the winch in the opposite direction (ie, the direction away from the limit position.) There is also need for a more limited way just in case, due to electrical or mechanical problems, leaving the operation of hoist limit bit more than normal. If you run into more limiter, linear contactor will open, therefore, can not be driven winch will exceed this limit position. If this happens, you need to ask a professional technician to check the lead to meet the more specific reasons limiter. Then, you can use thestarter toggle switch inside the elastic recovery process to deal with more problems, rather than tripping device or a hand-off the current contacts.A necessary condition for speedOf course, the simple fixed speed starter is replaced by variable speed drives. This makes things start to get interesting again! At a minimum, you need to add a speed control dial operation platform. Joystick is a better user interface, because it makes you move parts of a more intuitive control.Unfortunately, you can not just from your local console to send commands to control the old variable speed drives, in addition, you can not want it in the initial stages, will be able to enhance the safe and reliable and decentralized facilities. Most of the variable speed drive can not achieve these requirements, because they are not designed to do upgrading work. Drivers need to be set to release the brake before the motor can generate torque, and when parking, that is, before the revocation of torque, the brake will be the first action.For many years, DC motors and drives provide a number of common solutions, such as when they are in a variety of speeds with good torque characteristics. For most of the hoist of the large demand for DC motor is very expensive, and that the same type of AC motor than the much more expensive. Although the early AC drives are not very useful, as they have a very limited scope of application of the speed, but produced only a small low-speed torque. Now, with the DC drives the development of low cost and a large number of available AC motors has led to a communication-driven revolution.Variable speed AC drives in two series. Frequency converter has been widely known and, indeed, easy to use. These drives convert AC into DC, and then, and then convert it back to exchange, the exchange after the conversion is a different frequency. If the drive produced the exchange of 30Hz, 60Hz a normal motor will run at half speed. Theoretically, this is very good, but in practice, this will have a lot of problems. First of all, a typical linear motor 60Hz frequencies below 2Hz 3Hz area or there will be errors, and start cog (that urgent push, yank), or parking. This will limit your speed range lower than 20:1, almost not adapted to the operational phase of the fine adjustment. Second, many low-cost converter is not able to provide the rated torque at low speeds. Use of these drives, will result in the rapid move to upgrade the components or complete failure, precisely, when you try to upgrade a stable scientific instruments, you do not want to see this situation. Some new inverter is a closed-loop system (to get feedback from the motor to provide a more accurate speed control), and the motor will work quite well.Another series of AC drives is the flow vector type drive. These components require installation of the spindle motor encoder, encoder makes use of these drivescan accurately monitor the rotation of the motor armature. Processor accurately measured magnetic flux vector values that are required to make the armature at a given speed rotation. These drives allow infinite speed, so you actually can produce at zero speed to rated torque. These drives provide precise speed and position control, so these drives in high performance applications to be welcomed.(Based on PLC controllers provide system status and control options. This screen shows the operator full access to the nine-story elevator enhance the control panel.) PLC-based systemsIs the full name of a PLC programmable logic controller. First of all, PLC controller developed to replace the fifties and sixties-based industrial control system relay, they work in harsh industrial indoor environments. These are modular systems that have a large variety of I / O modules. The modular system can easily achieve the semi-custom hardware configuration assembled, and the resulting configuration is also very reasonable price. These modules include: position control module, the counter, A / D and D / A converter, and a variety of physical state or physical contact with closed output module. Large number of different types of I / O components and PLC module property makes it an effective way to assemble custom and semi custom control system.The biggest shortcoming of PLC systems is the lack of the real number of display to tell you what is being done and the PLC on the PLC program to help you.T he first is professional entertainment for the large-scale PLC system is one of the original in Las Vegas, MGM (now Bailey Company) of the riding and carriage system. Many manufacturers offer a standard PLC-based semi-automated acoustic systems and a host of signs, set the location of the command line interpreter, and the upgrading of the control system is also available. Using standard modules to set user-defined system configuration capability is based on the PLC controller of the greatest advantage.High-end controllerFor complex transmission, the controller became complex, more than speed, time and location control. They include complex instructions to write and record the movement contour, and the processing can immediately run the ability to multi-point instructions.Many large opera house is toward the direction of point lift system, where each one is equipped with a rope to enhance independent winches, rope equivalent to those of each dimmer circuit. When more than one hoist is used to enhance the individual part, the hoist must be fully synchronous, or the load to shift, so will lead to a separate winch becomes the risk of overload. Control system must be able to be selected to keep pace winch, or a hoist winch is not able to maintain synchronization with the other, can provide the same high-speed parking capacity. For a typical speed of 240 ft / min and a winch to maintain the rate of error of between 1 / 8 points of equipment, you only have less than three microseconds of time to identify problems and try to correct the error The hoist speed, make sure you fail, you start all the winch stop the group. This will require a large amount of computation, fast I / O interface, and easy to use to write software.For large rope control system has two very different solutions. The first is to use a separate console, the problem in general terms, this console should be installed in the appropriate location of the operator perspective. However, this not only from one angle to another angle, but still can not get an instruction to another instruction from the control. These difficulties have been partially resolved. Installed in different locations through the use of video cameras, and these cameras connected to the three-dimensional display graphics, these graphics enables the operator to observe from the perspective of any of the three coordinates in the expected direction of rope movement. These operators can make from a console for him at the actual angle, or closed circuit camera practical perspective, to observe the movement of the rope on the screen. For the complex interrelated moving parts, makes the implementation of the above observation Failure to control and find out easier.Another solution to the problem is a distributed system that uses multiple light console. This will allow the different operators in the same way the different aspects of control gear, we have improved the manual control device. A vivid example is the flower in a vegetable market in central London, the Royal Opera House, the program uses the above, where the control console 240 with ten motors. Each console has five playback device, and has been open, so that each motor has been assigned to a single console. An operator and a console can control all the devices, however, often may be running a console platform screen upgrade, another console is a console on the transmission device, and the third console is used to the necessary backgroundin the background image down.(edge-type portable console allows the operator many advantages from the start to control the movement of the machine, and provide three-dimensional image display.)ConclusionA huge change in the rope control system, a workstation has been developed from a push-button to complex multi-user computerized control system. When the control system to buy rope, you can always find to meet your needs. Control system performance is the most important security and reliability. These are the true value of the property, and you can expect the price to buy a suitable way of security. With a certain product manufacturers to work, he will make you know how to install it. And he will make contact with you and the users, those users have with similar requests.译文：电动卷扬机的控制对于电动机的控制，我们所知道的最好的方式就是使用由许多点动式按钮组成的简单的手工操作台。
电气工程及其自动化 外文翻译 外文文献 英文文献 短路电流
Short-circuit current1 Terms and DefinitionsThe following terms and definitions correspond largely to those defined in IEC 60 909. Refer to this standard for all terms not used in this book.The terms short circuit and ground fault describe faults in the isolation of operational equipment which occur when live parts are shunted out as a result.●Causes:1. Overtemperatures due to excessively high overcurrents.2. Disruptive discharges due to overvoltages.3. Arcing due to moisture together with impure air, especially on insulators.●Effects:1. Interruption of power supply.2. Destruction of system components.3. Development of unacceptable mechanical and thermal stresses inelectrical operational equipment.●Short circuit:According to IEC 60 909, a short circuit is the accidental or intentionalconductive connection through a relatively low resistance or impedance between two or more points of a circuit which are normally at differentpotentials.●Short circuit current:According to IEC 60 909, a short circuit current results from a shortcircuit in an electrical network.It is necessary to differentiate here between the short circuit current atthe position of the short circuit and the transferred short circuit currents in the network branches.●Initial symmetrical short circuit current:This is the effective value of the symmetrical short circuit current at the moment at which the short circuit arises, when the short circuitimpedance has its value from the time zero.●Initial symmetrical short circuit apparent power:The short circuit power represents a fictitious parameter. During theplanning of networks, the short circuit power is a suitable characteristicnumber.●Peak short circuit current:The largest possible momentary value of the short circuit occurring.●Steady state short circuit current:Effective value of the initial symmetrical short circuit current remaining after the decay of all transient phenomena.●DC aperiodic component:Average value of the upper and lower envelope curve of the short circuit current, which slowly decays to zero.●Symmetrical breaking current:Effective value of the short circuit current which flows through the contact switch at the time of the first contact separation.●Equivalent voltage source:The voltage at the position of the short circuit, which is transferred to the positive-sequence system as the only effective voltage and is used for the calculation of the short circuit currents.●Superposition method:The superposition method considers the previous load of the network before the occurrence of the short circuit. It is necessary to know the load flow and the setting of the transformer step switch.●Voltage factor:Ratio between the equivalent voltage source and the network voltage Un,divided by 3.●Equivalent electrical circuit:Model for the description of the network by an equivalent circuit.●Far-from-generator short circuit:The value of the symmetrical AC periodic component remains essentiallyconstant.●Near-to-generator short circuit:The value of the symmetrical AC periodic component does not remain constant. The synchronous machine first delivers an initial symmetrical short circuit current which is larger than twice the rated current of the synchronous machine.●Positive-sequence short circuit impedance:p••• The impedance of the positive-sequence system as seen from theposition of the short circuit.● Negative-sequence short circuit impedance:The impedance of the negative-sequence system as seen from theposition of the short circuit.● Zero-sequence short circuit impedanceThe impedance of the zero-sequence system as seen from the position of the short circuit. Three times the value of the neutral point to ground impedance occurs here.● Short circuit impedance:Impedance required for calculation of the short circuit currents at the position of the short circuit.1.2 Short circuit path in the positive-sequence systemFor the same external conductor voltages, a three-pole short circuit allows three currents of the same magnitude to develop between the threeconductors. It is therefor only necessary to consider one conductor in further calculations. Depending on the distance from the position of the short circuit from the generator, here it is necessary to consider near-to-generator andfar-from-generator short circuits separately.For far-from-generator and near-to-generator short circuits, the short circuit path can be represented by a mesh diagram with AC voltage source, reactances X and resistances R (Figure 1.2). Here, X and R replace allcomponents such as cables,conductors, transformers, generators and motors.Fig. 1.2: Equivalent circuit of the short circuit current path inthe positive-sequence systemThe following differential equation can be used to describe the short circuitprocesswhere w is the phase angle at the point in time of the short circuit. This assume that the current before S closes (short circuit) is zero. The inhomogeneous first order differential equation can be solved by determining the homogeneous solution ik and a particular solution i²k.The homogeneous solution, with the time constant g = L/R, solution yields: For the particular solution, we obtain:The total short circuit current is composed of both components:The phase angle of the short circuit current (short circuit angle) is then, in accordance with the above equation,For the far-from-generator short circuit, the short circuit current is therefore made up of a constant AC periodic component and the decaying DC aperiodic component. From the simplified calculations, we can now reach the following conclusions:●The short circuit current always has a decaying DC aperiodiccomponent in addition to the stationary AC periodic component.●The magnitude of the short circuit current depends on the operatingangle of the current. It reaches a maximum at c = 90 (purelyinductive load). This case serves as the basis for furthercalculations.●.The short circuit current is always inductive.1.4 Methods of short circuit calculationThe equivalent voltage source will be introduced here as the only effective voltage of the generators or network inputs for the calculation of short circuit currents. The internal voltages of generators or network inputs are short circuited, and at the position of the short circuit (fault position) the value ( is used as the only effective voltage (Figure 1.4).●The voltage factor c [5] considers (Table 1.1):●The different voltage values, depending on time and position●The step changes of the transformer switch●That the loads and capacitances in the calculation of the equivalentvoltage source can be neglected●The subtransient behavior of generators and motors●This method assumes the following conditions:●The passive loads and conductor capacitances can be neglected●The step setting of the transformers do not have to be considered●The excitation of the generators do not have to be considered●The time and position dependence of the previous load (loadingstate) of the network does not have to be consideredFig. 1.4: Network circuit with equivalent voltage sourcea) three-phase network, b) equivalent circuit in positivesequence system1.4.2 Superposition methodThe superposition method is an exact method for the calculation of the short circuit currents. The method consists of three steps. The voltage ratios and the loading condition of the network must be known before the occurrence of the short circuit. In the first step the currents, voltages and the internal voltages for steady-state operation before onset of the short circuit are calculated (Figure 1.5b). The calculation considers the impedances, power supply feeders and node loads of the active elements. In the second step the voltage applied to the fault location before the occurrence of the short circuit and the current distribution at the fault location are determined with a negative sign (Figure 1.5c). This voltage source is the only voltage source in the network. The internal voltages are short-circuited. In the third step both conditions are superimposed. We then obtain zero voltage at the fault location. The superposition of the currents also leads to the value zero. The disadvantage of this method is that the steady-state condition must be specified. The data for the network (effective and reactive power, node voltages and the step settings of the transformers) are often difficult to determine. The question also arises, which operating state leads to the greatest short circuit current. Figure 1.5 illustrates the procedure for the superposition method.Fig. 1.5: Principle of the superposition methoda) undisturbed operation, b) operating voltage at the faultlocation, c) superposition of a) and b)1.4.3 Transient calculationWith the transient method the individual operating equipment and, as a result, the entire network are represented by a system of differential equations. The calculation is very tedious. The method with the equivalent voltage source is a simplification relative to the other methods. Since 1988, it has been standardized internationally in IEC 60 909. The calculation is independent of a current operational state. In thisbook, we will therefore deal with and discuss the method with the equivalent voltage source.1.5 Calculating with reference variablesThere are several methods for performing short circuit calculations with absolute and reference impedance values. A few are summarized here and examples are calculated for comparison. To define the relative values, there are two possible reference variables.For the characterization of electrotechnical relationships we require the fourparameters:● Voltage U in V● Current I in A● Impedance Z in W● Apparent power S in VA.Three methods can be used to calculate the short circuit current:1. The Ohm system: Units: kV, kA, V, MVA2.The pu system:This method is used predominantly for electricalmachines; all four parameters u, i, z and s are given as per unit (unit = 1).The reference value is 100 MVA. The two reference variables for thissystem are UB and SB.Example: The reactances of a synchronousmachine Xd, X¢d, X²d are given in pu or in % pu, multiplied by 100 %.3.The %/MVA system:This system is especially well suited for the fastdetermination of short circuit impedances. As formal unit only the %symbol is add.短路电流1 术语和定义以下术语和定义对应IEC 标准60 909。
自动化输配电系统中英文对照外文翻译文献
中英文资料翻译A Maintenance Optimization Program for Utilities’Transmission and Distribution SystemsABSTRACT: Today, preserving and enhancing system reliability and reducing operations and maintenance costs are top priorities for electric utilities. As system equipment continue to age and gradually deteriorate, the probability of service interruption due to component failure increases. An effective maintenance strategy is essential in delivering safe and reliable electric power to customers economically. The objective of this paper is to provide a framework for a predictive, condition-based, and cost effective maintenance optimization program for transmission and distribution systems.1 INTRODUCTIONIn principle, improving system reliability and reducing Operations and Maintenance costs are top priorities of electric utilities. In an increasingly competitive power delivery environment, electric utilities are forced to apply more proactive methods of utility asset management. One of the main components of electric power delivery asset management is the capital budgeting and Operations and Maintenance of existing facilities. Since in many cases the cost of construction and equipment purchases are fixed, Operations and Maintenance expenditures is the primary candidate for cost cutting and potential savings. As system equipment continue to age and gradually deteriorate, the probability of service interruption due to component failure increases.Electric utilities are confronted with many challenges in this new era of competition: rising Operations and Maintenance costs, growing demand on systems, maintaining high levels of reliability and power quality, and managing equipment aging.Therefore, the health of equipment is of utmost importance to the industry because revenues are affected by the condition of equipment. When demand is high and equipment is in working order, substantial revenues can be realized. On the contrary, unhealthy equipment can result in service interruption, customer dissatisfaction, loss of good will, and eventual loss of customers. An effective maintenance strategy is essential to delivering safe and reliable electric power to customers economically.2 RELIABILITY CENTERED MAINTENANCE (RCM)During the late 1960’s, t he aircraft industry was on the verge of manufacturing the first “jumbo jets”. The new 747’s were three times the size ofany other passenger jets currently in the air. The recognized size of the 747, its new engines, and its many technology advances in structures, avionics, and the like, all led to Federal Aviation Administration (FAA) to initially take the position that preventive maintenance on the 747 would be very extensive – so extensive, in fact, that the airlines could not likely operate this airplane in a profitable fashion. This problem led the aircraft industry to completely reevaluate its PM program. What resulted from this effort was a whole new approach that employed a decision-tree process for ranking PM tasks that were necessary to preserve critical aircraft functions during flight [3]. This new technique was eventually approved by the FAA and soon thereafter evolved into what is known as Reliability Centered Maintenance (RCM). RCM used by the airline industry led to major reduction in labor,material cost and inventory cost. Further it applied to nuclear power industry in the 1980’s. Today,RCM is the maintenance technique of choice for many industries including power industries.Unlike the airline industry which had the advantage of being able to work with manufacturers to create an RCM program for a new generation of equipment, the utility industry, especially the electric power generation industry, has had to adopt RCM as a modification of long-established maintenance practices at existing plants [4]. Despite the costs associated with the implementation of these RCM programs in “midstream”, they have been found to pay for themselves in very short order.RCM, as has been mainly applied to nuclear power plants, often requires the largest amount of maintenance because of safety and environmental considerations. However, with these successful programs now operating, fossil power plants and power transmission and distribution systems have recently been getting into the mix. Because these facilities face a less restrictive regulatory environment, they should be able to directly apply the streamlines forms of RCM much more easily, thus reducing the implementation costs.The first step in revamping a maintenance program is to implement an RCM approach whichwill help establish priorities for a new program. Specifically, RCM is a set of methods and tools aimed at helping a utility to determine the minimum set of preventive maintenance tasks necessary to appropriately address critical equipment failures without compromising service reliability. RCM is a structured process used to determine optimal maintenance requirements for equipment in a particular operating environment. Itcombines the strategies of corrective maintenance, preventive maintenance and predictive maintenance, and applies these strategies where each is appropriate, based on the consequence and frequency of functional failures. This combination produces a maintenance program which optimizes both reliability and cost effectiveness. For major pieces of equipment, such as power transformers, RCM may indicate that predictive maintenance is an attractive option, given the decreasing cost of sensor and diagnostic technology and the increasing cost of running the equipment to failure.RCM is a condition-based maintenance program that focuses on preventing failures that are likely to be the most serious. RCM and Predictive Maintenance (PDM) analyses complement each other, and when they are performed concurrently, offer an excellent approach to maintenance optimization. In the last few years, the sophistication of monitoring equipment on the market and the falling price of electronics and computers have made the on-site monitoring applications a cost effective reality.The very basic concepts and underlying principles of the RCM can be explained very easily. Its main methodology can be reduced to the following four points:1) preserve system functions2) identify dominant failure modes3) prioritize function needs so that budget can be focused on preserving most critical functions4) select only applicable and effective maintenance tasksSome of the benefits of RCM are:1) Reduces major corrective actions2) Eliminates unnecessary overhauls and routine tasks that provide little benefits3) Optimizes the frequency of required overhauls4) Increases use of predictive technology that help with resource planning5) Decreases use of intrusive tasks that can induce equipment failures6) Improves cost-effectiveness of routine tasks7) Creates documented technical bases for maintenance programs8) Allows easy implementation by incorporating existing maintenance practices that have proven to be cost-effective9) Processes Knowledge, communications, and teamworkInexpensive solid state sensors are being developed, for example, that can be inserted in transformer oil to detect the presence of gases produced when insulation begins to deteriorate. Once the information from predictive maintenance technology becomesavailable, it needs to be integrated with on-line data from across a power network and from historical records.3 NEW TECHNOLOGIESThere are many technologies available today, and several new methods are being investigated to determine the equipment condition [5]. The following are just a few applications for monitoring power delivery equipment:Ultrasonic Noise AnalysisThe presence of tones in the ultrasonic range can be an indication of leaks of air, gas, steam, and vacuum. Ultrasonic noise can be emitted as a result of friction between moving parts.Partial Discharge DetectionThis technology employs an electrical sensor to detect the initial insulation breakdown in electrical equipment such as insulators and terminators. Partial discharge detection is used to detect incipient failures before significant damage occurs. Transformer Gas-in-Oil AnalysisThis is needed to keep the transformer on-line as much as possible. One indicator of abnormalities is the dissolved gas content in the transformer oil. Certain gas levels can indicate aging, the need for maintenance, or potential failure.Infrared ThermographyThermography surveys involving the use of an infrared camera to detect hot spots in large motors used in power plants.Sound Intensity MeasurementSound Intensity Meter is needed to identify potential problems in equipment and record the historical changes in sound and output of equipmentFor transmission and distribution systems, sensors such as transformer fault gas analyzer might prove to be beneficial. This device provides real-time measurement of the four key gases associated with fault currents in transformer: carbon monoxide, hydrogen, acetylene, and ethylene. The next step is to incorporate an additional sensor to detect the presence of moisture which can reduce dielectric strength and lead to failure. This will be used with another device that measures the transformer loading so that the evolution of key gases and moisture can be characterized as a function of the load. With the moisture sensor and load current monitor we can develop accurate criteria for loading transformers under stressful conditions rather than having to rely on the overly conservative ratings now provided.4 PROPOSED INTEGRATED APPROACHAn integrated approach for transmission and distribution systems would ensure that equipment or subsystems leading to serve a particular load would receive uniform and consistent level of maintenance in all departments, thus enhancing and optimizing the maintenance process.In order to establish a maintenance program, the RCM process needs to be the driving point. Figure 2. Shows different strategies required for a maintenance optimization program. The classical RCM process involves identifying the systems to be studied, their functions, functional failures, failure modes, failure causes, and the maintenance task selectio.The most critical pieces of equipment which affect the overall function of the system need to be identified. In other words, we need to identify equipment with severe consequences when failed. Also, critical customers and the equipment leading to their loads need to be identified. All equipment affecting these customers need to be analyzed, and the most critical pieces of equipment should be determined. We also need to understand the customer needs in terms of reliability, safety, power quality, cost, etc. These attributes must be weighted to determine the optimum maintenance policy to deal with these customers.In order to optimize the utilities’ maintenance program, all relevant information must be used to most effectively initiate, schedule, track, record, and analyze maintenance tasks. An open communication protocol that enables various monitoring devices (regardless of the manufacturer) to talk to each other, with utilityoffices, and with control centers would best suit the needs of electric utilities by integrating various data sources and other software modules.Currently, many large utility organizations perform some equipment diagnostic tests. Many have computerized their maintenance work management functions including retaining maintenance histories, logging significant operational activities, and maintaining a library of design information for equipment. The proper communication, integration and analysis of all of this information would result in more accurate recommendations concerning when to perform maintenance and/or how to operate a specific piece of equipment.A typical problem in the industry is that, at times, a large amount of data is collected but it is not integrated and processed expediently for a quick evaluation. This results in the inability to make immediate Operations and Maintenances, therebyadding cost for thecollection of data while failing to provide cost benefit which could have been realized.Other factors that may contribute to maintenance improvement are: application of inexpensive sensor techniques and effective diagnostics to maintain equipment’s health; data coordination from multiple sources for analysis and decision making; a system for efficient exchange of information across T&D and substations; and experienced pool of trained professionals.The management should be prepared to invest in staff and hardware/software to actively manage the maintenance program. A team approach to RCM must be retained and the concept of RCM must be accepted in the organization.In order to use appropriate software and hardware, education and training efforts should be an integral part of this process. The understanding of the basics of utility’s maintenance program and the working knowledge of the tools required by the staff must be assured.The key to sustaining a successful maintenance program is the development of a process that will ensure the continuance of maintenance program over a long period of time. It is necessary to periodically review and update the maintenance program using a structured method.5 CONCLUSIONToday, cutting operations and maintenance costs and preserving service reliability are the top priorities for managers of utility transmission and distribution systems. The concept of RCM is sound and should provide utilities with a structured approach to a maintenance program with an optimum balance between cost of maintenance and reliability improvement. RCM and PDM analyses complement each other, and when performed simultaneously, offer an excellent approach to maintenance optimization.一种实用的输配电系统的维护优化计划摘要：今天，维护和提高系统的可靠性和降低运营和维护成本是电力的首要任务。
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中英文资料外文翻译Faults on Power SystemsEach year new design of power equipment bring about increased reliability of operation. Nevertheless, equipment failures and interference by outside sources occasionally result in faults on electric power systems. On the occurrence of a fault , current an voltage conditions become abnormal, the delivery of power from the generating station to the loads may be unsatisfactory over a considerable area, and if the faulted equipment is not promptly disconnected from the remainder of the system, damage may result to other pieces of operating equipment.A faulty is the unintentional or intentional connecting together of two or more conductors which ordinarily operate with a difference of potential between them. The connection between the conductors may be by physical metallic contact or it may be through an arc. At the fault, the voltage between the two parts is reduced to zero in the case of metal-to-metal contacts, or to a very low value in case the connection is through an arc. Currents of abnormally high magnitudeflow through the network to the point of fault. These short-circuit currents will usually be much greater than the designed thermal ability of the condition in the lines or machines feeding the fault . The resultant rise in temperature may cause damage by the annealing of conductors and by the charring of insulation. In the period during which the fault is permitted to exist, the voltage on the system in the near vicinity of the fault will be so low that utilization equipment will be inoperative. It is apparent that the late conditions that exist during a fault, and provide equipment properly adjusted to open the switches necessary to disconnect the faulted equipment from the remanding of the system. Ordinarily it is desirable that no other switches on the system are opened, as such behavior would result in unnecessary modification the system circuits.A distinction must be made between and an overload. An overload implies only that loads greater than the designed values have been imposed on system. Under such a circumstance the voltage at the overload point may be low, but not zero. This undervoltage condition may extend for some distance beyond the overload point into the remainder of the system. The current in the overload equipment are high and may exceed the thermal design limits. Nevertheless, such currents are substantially lower than in the case of a fault. Service frequently may be maintained, but at below-standard voltage.Overloads are rather common occurrences in homes. For example, a housewife might plug five waffle irons into the kitchen circuit during a neighborhood part. Such an overload, if permitted to continue,would cause heating of the wires from the power center and might eventually start a fire. To prevent such trouble, residential circuits are protected by fuses or circuit breakers which open quickly when currents above specified values persist. Distribution transformers are sometimes overloads as customers install more and more appliances. The continuous monitoring of distribution circuits is necessary to be certain that transformers sizes are increased as load grows.Faults of many types and causes may appear on electric power systems. Many of us in our homes have seen frayed lamp cords which permitted the two conductors of the cord to come in contact with each other. When this occurs, there is a resulting flash, and if breaker or fuse equipment functions properly, the circuit is opened.Overhead lines, for the most part, are constructed of bare conductors. There are sometimes accidentally brought together by action of wind, sleets, trees, cranes, airplanes, or damage to supporting structures. Overvoltages due to lighting or switching nay cause flashover of supporting or from conductor to conductor. Contamination on insulators sometimes results in flashover even during normal voltage conditions.The conductors of underground cables are separated from each and from ground by solid insulation, which nay be oil-impregnated paper or a plastic such polyethylene. These materials undergo some deterioration with age, particularly if overloads on the cables have resulted in their operation at elevated temperature. Any small void present in the body of the insulating material will results in ionizationof the gas contained therein, the products of which react unfavorably with the insulation. Deterioration of the insulation may result in failure of the material to retain its insulating properties, and short circuits will develop between the cable conductors. The possibility of cable failure is increased if lightening or switching produces transient voltage of abnormally high values between the conductors.Transformer failures may be the result of insulation deterioration combined with overvoltage due to lightning or switching transients. Short circuit due to insulation failure between adjacent turns of the same winding may result from suddenly applied overvoltage. Major insulation may fail, permitting arcs to be established between primary and secondary windings or between winding and grounded metal parts such as the core or tank.Generators may fail due to breakdown of the insulation between adjacent turns in the same slot, resulting in a short circuit in a single turn of the generator. Insulation breakdown may also occur between one of the winding and the grounded steel structure in which the coils are embedded. Breakdown between different windings lying in the same slot results in short-circuiting extensive section of machine.Balanced three-phase faults, like balanced three-phase loads, may be handled on a lineto-neutral basis or on an equivalent single-phase basis. Problems may be solved either in terms of volts, amperes, and ohms. The handing of faults on single-phase lines is of course identical to the method of handing three-phase faults on an equivalent single-phase basis.Faults may be classified as permanent or temporary. Permanent faults are those in which insulation failure or structure failure produces damage that makes operation of the equipment impossible and requires repairs to be made. Temporary faults are those which may be removed by deenergizing the equipment for a short period of time, short circuits on overhead lines frequently are of this nature. High winds may cause two or more conductions to swing together momentarily. During the short period of contact. An arc is formed which may continue as long as line remains energized. However, if automatic equipment can be brought into operation to service as soon as the are is extinguished. Arcs across insulators due to overvoltages from lighting or switching transients usually can be cleared by automatic circuit-breaker operation before significant structure damage occurs.Because of this characteristic of faults on lines, many companies operate following a procedure known as high-speed reclosing. On the occurrence of a fault, the line is promptly deenergized by opening the circuit breakers at each end of the line. The breakers remain open long enough for the arc to clear, and then reclose automatically. In many instances service is restored in a fraction of a second. Of course, if structure damage has occurred and the fault persists, it is necessary for the breakers to reopen and lock open.电力系统故障每年新设计的电力设备都使系统的可靠性不断提高，然而，设备的使用不当以及一些偶然遇到的外在因素均会导致系统故障的发生。