第一篇:電氣工程及其自動(dòng)化專業(yè)英語第6章6-3翻譯
Section 3 Operation and Control of Power Systems 第3節(jié) 操作和控制的電力系統(tǒng)
The purpose of a power system is to deliver the power the customers require in real time, on demand, within acceptable voltage and frequency limits, and in a reliable and economic manner.該系統(tǒng)的目的,權(quán)力是為客戶提供電力的時(shí)間為客戶需要實(shí)際需求,對(duì),在可接受的電壓和頻率的限制,在一個(gè)可靠和經(jīng)濟(jì)的方式。In normal operation of a power system, the total power generation is balanced by the total load and transmission losses.在電力系統(tǒng)正常運(yùn)行的,總發(fā)電是平衡的總負(fù)荷和傳輸?shù)膿p失。The system frequency and voltages on all the buses are within the required limits, while no overloads on lines or equipment are resulted.該系統(tǒng)的頻率和電壓的所有公共汽車都在規(guī)定的限額,而沒有超載或設(shè)備上線造成的。However, loads are constantly changed in small or large extents, so some control actions must be applied to maintain the power system in the normal and economic operation state.但是,負(fù)載不斷變化幅度小或大,所以一些控制行動(dòng)必須適用于維持在正常和經(jīng)濟(jì)運(yùn)行狀態(tài)的電力系統(tǒng)。
Optimal economic operation 優(yōu)化經(jīng)濟(jì)運(yùn)行
It is an important problem how to operate a power system to supply all the(complex)loads at minimum cost.這是一個(gè)重要的問題如何操作電源系統(tǒng),以提供所有的負(fù)載以最低的成本(復(fù)雜)。The basic task is to consider the cost of generating the power and to assign the allocation of generation(P Gi)to each generator to minimize the total “production cost” while satisfying the loads and the losses on the transmission lines.其基本任務(wù)是考慮發(fā)電成本的生成和分配產(chǎn)生的分配性(P基)每個(gè)發(fā)電機(jī),以盡量減少總的“生產(chǎn)成本”,同時(shí)滿足負(fù)載和傳輸線路上的損失。The total cost of operation includes fuel, labor, and maintenance costs, but for simplicity the only variable costs usually considered are fuel costs.The fuel-cost curves for each generating unit are specified, the cost of the fuel used per hour is defined as a function of the generator power output.When hydro-generation is not considered, it is reasonable to choose the PGi on an 總的經(jīng)營成本,包括燃料,勞動(dòng)和 維修費(fèi)用,但只有簡單的可變成本通常被認(rèn)為是燃料成本。曲線每個(gè)機(jī)組的燃料成本是指定的,時(shí)間成本占燃料使用的是輸出功率定義為一個(gè)函數(shù)的發(fā)電機(jī)。當(dāng)水文一代是不考慮它是合理的選擇上一的PGI instantaneous basis(ie always to minimize the present production cost rate).瞬間的基礎(chǔ)上(即始終以減低目前的生產(chǎn)成本率)。With hydro-generation, however, in dry periods, the replenishment of the water supply may be a problem.隨著水電發(fā)電,但是,在干燥的時(shí)期,供應(yīng)補(bǔ)給的水可能是個(gè)問題。The water used today may not be available in the future when its use might be more advantageous.Even without the element of the prediction involved, the problem of minimizing production cost over time becomes much more complicated.今天使用的可能不會(huì)在將來提供其使用時(shí),可能會(huì)更有利的水。即使沒有參與預(yù)測(cè)的元素,最大限度地減少生產(chǎn)成本的問題變得更加復(fù)雜。It should be mentioned that economy of operation is not the only possible consideration.應(yīng)當(dāng)提及的是經(jīng)濟(jì)運(yùn)行的不是唯一可能的考慮。If the “optimal” economic dispatch requires all the power to be imported from a neighboring utility through a single transmission link, considerations of system security might preclude that solution.如果在“最佳”的經(jīng)濟(jì)調(diào)度要求所有的權(quán)力,是從鄰國進(jìn)口的效用,通過一個(gè)單一的傳輸鏈路,系統(tǒng)安全的考慮可能會(huì)排除這種解決辦法。When water used for hydro-generation is also used for irrigation, nonoptimal releases of water may be required.Under adverse atmospheric conditions it may be necessary to limit generation at certain fossil-fuel plants to reduce emissions.當(dāng)水發(fā)電用于水力發(fā)電也用于灌溉,水nonoptimal釋放可能是必要條件。不良大氣下它可能需要限制某些植物代化石燃料,以減少排放。
In general, costs, security and emissions are all areas of concern in power plant operation, and in practice the system is operated to effect a compromise between the frequently conflicting requirements.一般而言,成本,安全和排放裝置運(yùn)行一切權(quán)力領(lǐng)域關(guān)注,并在實(shí)踐中系統(tǒng)的運(yùn)作產(chǎn)生影響,要求折衷之間經(jīng)常發(fā)生沖突。
Power system control 電力系統(tǒng)控制
Power system control is very important issue to maintain the normal operation of a system.電力系統(tǒng)的控制是很重要的問題,以維持系統(tǒng)的正常運(yùn)行。System voltage levels, frequency, tie-line flows, line currents, and equipment loading must be kept within limits determined to be safe in order to provide satisfactory service to the power system customers.系統(tǒng)電壓水平,頻率,聯(lián)絡(luò)線流,線電流和設(shè)備裝載必須保持確定的限度內(nèi)是安全的,以提供滿意的服務(wù),電力系統(tǒng)的客戶。
Voltage levels, line currents, and equipment loading may vary from location to location within a system, and control is on a relatively l ocal basis.電壓等級(jí),線路電流和設(shè)備負(fù)荷可能不同地點(diǎn)間的系統(tǒng)內(nèi),控制相對(duì)升厄恰爾基礎(chǔ)上。
For example, generator voltage is determined by the field current of each particular generating unit;however, if the generator voltages are not coordinated, excess var flows will result.Similarly, loading on individual generating units is determined by the throttle control on thermal units or the gate controls on hydro-units.Each machine will respond individually to the energy input to its prime mover.Transmission line loadings are affected by power input from generating units and their loadings, the connected loads, parallel paths for power to flow on other lines, and their relative impedances.例如,發(fā)電機(jī)電壓是由該領(lǐng)域目前的每一個(gè)具體單位產(chǎn)生,但是,如果發(fā)電機(jī)電壓不配合,無功流量將過剩的結(jié)果。同樣,對(duì)個(gè)別單位負(fù)荷發(fā)電,是由熱量單位或確定的控制油門水文單位的大門管制。每臺(tái)機(jī)器回應(yīng)個(gè)別的能量投入到其原動(dòng)力。輸電線路荷載的影響,輸入功率發(fā)電機(jī)組和他們的負(fù)荷,連接的負(fù)載,其他電力線平行的道路上流動(dòng)以及其相對(duì)阻抗。
Active power and frequency control 有功功率和頻率控制
For satisfactory operation of a power system, the frequency should remain nearly constant.Relatively close control of frequency ensures constancy of speed of induction and synchronous motors.Constancy of speed of motor drives is particularly important for satisfactory performance of all the auxiliary drives associated with the fuel, the feed-water and the combustion air supply systems.In a network, considerable drop in frequency could result in high magnetizing currents in induction motors and transformers.對(duì)于電力系統(tǒng)運(yùn)行合格的,頻率應(yīng)該保持幾乎不變。較為密切的保證電動(dòng)機(jī)變頻調(diào)速同步恒定速度感應(yīng)和。驅(qū)動(dòng)電機(jī)轉(zhuǎn)速恒定,尤其是在重要的關(guān)聯(lián)的所有輔助驅(qū)動(dòng)器的表現(xiàn)令人滿意燃料,飼料,水和空氣供給系統(tǒng)燃燒。在網(wǎng)絡(luò),大幅下降的頻率可能會(huì)導(dǎo)致電機(jī)和變壓器激磁電流的高感應(yīng)。The extensive use of electric clocks and the use of frequency for other timing purpose require accurate maintenance of synchronous time which is proportional to integral of frequency.As a consequence, it is necessary to regulate not only the frequency itself but also its integral.The frequency of a system is dependant on active power balance.As frequency is a common factor throughout the system, a change in active power demand at one point is reflected throughout the system by a change in frequency.廣泛使用的電動(dòng)時(shí)鐘和定時(shí)的目的使用的頻率為其他需要作為一個(gè)同步時(shí)間是成正比的積分。結(jié)果準(zhǔn)確的頻率維持,它是要規(guī)范,不僅本身的頻率,而且它的積分。該系統(tǒng)是一個(gè)頻率依賴于積極的力量平衡。由于頻率是1點(diǎn)共同的因素在整個(gè)系統(tǒng),有源電力需求的變化是反映整個(gè)系統(tǒng)的頻率變化。
Because there are many generators supplying power into the system, some means must be provided to allocate change in demand to the generators.A speed governor on each generating unit provides the primary speed control function, while supplementary control originating at a central control center allocates generation.In an interconnected system with two or more independently controlled areas, in addition to control of frequency, the generation within each area has to be controlled so as to maintain scheduled power interchange.The control of generation and frequency is commonly referred to as load-frequency control(LFC).在一個(gè)相互聯(lián)系的系統(tǒng)控制區(qū)的兩個(gè)或兩個(gè)以上獨(dú)立此外,在控制的頻率,在每個(gè)地區(qū)的一代已被控制,以保持計(jì)劃的權(quán)力交換。的生成控制和頻率通常被稱為頻率為負(fù)載控制(消失模)。
The control measures of power and frequency include: 功率和頻率的控制措施包括:
(1)Regulation of the generator's speed governor(1)總督調(diào)節(jié)發(fā)電機(jī)的速度
(2)Underfrequency load shedding(2)低頻減載
(3)Automatic generation control(AGC)(3)自動(dòng)發(fā)電控制(AGC)
AGC is an effective means for power and frequency control in large-scale power systems.大型電力系統(tǒng)AGC的是一個(gè)有效的手段功率和頻率控制大。In an interconnected power system, the primary objectives of AGC are to regulate frequency to the specified nominal value and to maintain the interchange power between control areas at the scheduled values by adjusting the output of the selected generators.This function is commonly referred to as load-frequency control.在一個(gè)相互聯(lián)系的電力系統(tǒng),自動(dòng)增益控制的主要目的是調(diào)節(jié)頻率到指定的名義價(jià)值,并保持在預(yù)定值,通過調(diào)整所選發(fā)電機(jī)輸出控制區(qū)之間的交換能力。這個(gè)函數(shù)通常被稱為負(fù)載頻率控制。A secondary objective is to distribute the required change in generation among units to minimize operating costs.第二個(gè)目標(biāo)是改變單位之間分配在一代人的需要,以減低經(jīng)營成本。
In an isolated power system, maintenance of interchange power is not an issue.Therefore, the function of AGC is to restore frequency to the specified nominal value.This is accomplished by adding a reset or integral control which acts on the load reference setting of the governors of unit on AGC.在一個(gè)孤立的電力系統(tǒng),電力維修轉(zhuǎn)乘不是一個(gè)問題。因此,AGC功能是恢復(fù)到指定的頻率標(biāo)稱值。這是通過增加一個(gè)或積分復(fù)位控制于負(fù)載上的AGC的機(jī)組省長設(shè)置參考行為。The integral control action ensures zero frequency error in the steady state.The supplementary generation control action is much slower than the primary speed control action.As such it takes effect after the primary speed control(which acts on all units on regulation)has stabilized the system frequency.Thus, AGC adjusts load reference settings of selected units, and hence their output power, to override the effects of the composite frequency regulation characteristics of the power system.積分控制作用的保證零穩(wěn)態(tài)頻率誤差英寸補(bǔ)充發(fā)電控制行動(dòng)的動(dòng)作比主慢速度控制。因此,它需要具有效力后的首要速度控制(對(duì)所有單位的行為,對(duì)監(jiān)管)穩(wěn)定的系統(tǒng)頻率。因此,AGC的機(jī)組負(fù)荷調(diào)整選定的參考設(shè)置,因此它們的輸出功率,覆蓋電力系統(tǒng)的影響,復(fù)合材料的頻率調(diào)節(jié)特性。In so doing, it restores the generation of all other units not on AGC to scheduled values.在這樣做時(shí),沒有恢復(fù)的AGC所有其他單位代定值。
Reactive power and voltage control 無功功率和電壓控制
For efficient and reliable operation of power systems, the control of voltage and reactive power should satisfy the following objectives: 為了有效和可靠的電力系統(tǒng)運(yùn)行的目標(biāo),在控制電壓和無功功率,應(yīng)符合下列條件:
(1)Voltages at the terminals of all equipment in the system are within acceptable limits.(1)系統(tǒng)電壓的所有終端設(shè)備,在可接受的限度內(nèi)。Both utility equipment and customer equipment are designed to operate at a certain voltage rating.這兩種工具設(shè)備和客戶設(shè)備的設(shè)計(jì)運(yùn)行在一定的電壓等級(jí)。
Prolonged operation of the equipment at voltages outside the allowable range could adversely affect their performance and possibly cause them damage.該設(shè)備在長期運(yùn)行電壓允許范圍以外的可能影響其性能,并可能導(dǎo)致他們的傷害。
(2)System stability is enhanced to maximize utilization of the transmission system.(2)提高系統(tǒng)的穩(wěn)定性,以最大限度地提高系統(tǒng)利用率的傳輸。
(3)The reactive power flow is minimized so as to reduce RI2 and XI2 losses to a practical minimum.(3)無功功率流最小化,以減少RI2和XI2實(shí)際損失減至最低。This ensures that the transmission system operates efficiently, ie mainly for active power transfer.這確保了傳輸系統(tǒng)的運(yùn)作效率,即轉(zhuǎn)讓主要是積極的力量。
The problem of maintaining voltages within the required limits is complicated by the fact that the power system supplies power to a vast number of loads and is fed from many generating units.As loads vary, the reactive power requirements of the transmission system vary.Since reactive power can not transmitted over long distances, voltage control has to be effected by using special devices dispersed throughout the system.This is in contrast to the control of frequency which depends on the overall system active power balance.問題所需的限度內(nèi)保持電壓是復(fù)雜的是,電力系統(tǒng)提供電源的負(fù)載數(shù)量龐大,而且是從許多單位產(chǎn)生厭倦。由于負(fù)載不同,輸電系統(tǒng)的無功需求各不相同。由于反應(yīng)權(quán)力不能傳輸?shù)木嚯x長,電壓控制,必須使用特殊設(shè)備實(shí)施分散在整個(gè)系統(tǒng)。這種平衡是相對(duì)于頻率的控制依賴于整體的系統(tǒng)的積極力量。正確的選擇和設(shè)備的協(xié)調(diào) The proper selection and coordination of equipment for controlling reactive power and voltage are among the major challenges of power system engineering.正確的選擇和控制無功功率和電壓的設(shè)備之間的協(xié)調(diào),電力系統(tǒng)的工程的重大挑戰(zhàn)。
The control of voltage levels is accomplished by controlling the production, absorption, and flow of reactive power at all levels in the system.The generating units provide the basic means of voltage control;the automatic voltage regulators control field excitation to maintain a scheduled voltage level at the terminals of the generators.Additional means are usually required to control voltage throughout the system.The devices used for this purpose may be classified as follows: 水平控制電壓是通過控制生產(chǎn),吸收,無功和功率流在系統(tǒng)各級(jí)英寸的發(fā)電機(jī)組提供了電壓控制的基本手段;自動(dòng)電壓調(diào)節(jié)器控制勵(lì)磁電壓,以保持預(yù)定的水平在碼頭的發(fā)電機(jī)。通常需要額外的手段來控制整個(gè)系統(tǒng)的電壓。這些器件用于此目的,可分為下列幾類:
(1)Sources or sinks of reactive power, such as shunt capacitors, shunt reactors, synchro-nous condensers, and static var compensators(SVCs).(1)資料來源或無功功率匯,如并聯(lián)電容器,電抗器,同步奴斯冷凝器和靜態(tài)2004/12)無功補(bǔ)償器(。
(2)Line reactance compensators, such as series capacitors.(2)補(bǔ)償電容器電抗線,如系列。
(3)Regulating transformers, such as tap-changing transformers and boosters.(三)調(diào)壓變壓器的助推器,如調(diào)壓變壓器和。
Shunt capacitors and reactors, and series capacitors provide passive compensation.They are either permanently connected to the transmission and distribution system, or switched.并聯(lián)電容器和電抗器,電容器,并提供一系列的被動(dòng)賠償。他們要么永久連接到傳輸和分配系統(tǒng),或切換。
They contribute to voltage control by modifying the network characteristics.Synchronous condensers and SVCs provide active compensation, the reactive power absorbed/supplied by them is automatically adjusted so as to maintain voltages of the buses to which they are connected.Together with the generating units, they establish voltages at specific points in the system.Voltages at other locations in the system are determined by active and reactive power flows through various circuit elements, including the passive compensating devices.電壓控制通過修改網(wǎng)絡(luò)特性。同步冷凝器和2004/12積極提供補(bǔ)償,無功功率吸收/他們提供的是自動(dòng)調(diào)整,以維持巴士電壓的它們所連接的設(shè)備。連同生成,他們建立電壓在特定的點(diǎn)在系統(tǒng)中。電壓在系統(tǒng)的其他地點(diǎn)取決于有功,無功流經(jīng)各種電路元件,包括無源補(bǔ)償裝置。
三。翻譯成中文以下
When two or more synchronous machines are interconnected, the stator voltages and currents of all the machines must have the same frequency and the rotor mechanical speed of each is synchronized to this frequency.Therefore, the rotors of all interconnected machines must be in synchronism.In a generator, the electromagnetic torque opposes rotation of the rotor, so that mechanical torque must be applied by the prime mover to sustain rotation.當(dāng)兩個(gè)或多個(gè)同步電機(jī)是相互聯(lián)系,定子電壓和電流的所有機(jī)器必須具有相同的頻率和轉(zhuǎn)子的機(jī)械速度同步每到這個(gè)頻率。因此,互聯(lián)機(jī)轉(zhuǎn)子所有必須同步。在一臺(tái)發(fā)電機(jī),電磁轉(zhuǎn)矩轉(zhuǎn)子旋轉(zhuǎn)的反對(duì),使機(jī)械扭矩必須由總理先行者申請(qǐng)維持旋轉(zhuǎn)。The electrical torque(or power)output of the generator is changed only by changing the mechanical torque input by the prime mover.電氣力矩(或功率)發(fā)電機(jī)的輸出是通過改變只改變了原動(dòng)機(jī)的機(jī)械轉(zhuǎn)矩輸入。The effect of increasing the mechanical torque input is to advance the rotor to a new position relative to the revolving magnetic field of the stator.Conversely, a reduction of mechanical torque or power input will retard the rotor position.In a synchronous motor, the roles of electrical and mechanical torques are reversed compared to those in a generator.輸入的影響是增加了機(jī)械扭矩推進(jìn)到一個(gè)新的轉(zhuǎn)子相對(duì)位置的定子旋轉(zhuǎn)磁場(chǎng)。反過來,一個(gè)或減少機(jī)械扭矩輸入功率會(huì)阻礙轉(zhuǎn)子的位置。在同步電機(jī),機(jī)械力矩的作用是相反的電氣和發(fā)電機(jī)相比,那些在1。
第二篇:電氣工程自動(dòng)化專業(yè)
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真誠地感謝您在百忙之中瀏覽這份求職材料。這里有一顆熱情而赤誠的心渴望得到您的了解與幫助,為了發(fā)揮自己的才能、實(shí)現(xiàn)自己的人生價(jià)值,謹(jǐn)向您毛遂自薦。我是一名即將畢業(yè)的電氣工程及其自動(dòng)化專業(yè)本科生,屆時(shí)將獲得工學(xué)學(xué)士學(xué)位。大學(xué)四年,奠定了我扎實(shí)的專業(yè)理論基礎(chǔ),良好的組織能力,團(tuán)隊(duì)協(xié)作精神,務(wù)實(shí)的工作作風(fēng)。我性格開朗、待人熱情、辦事穩(wěn)重、善于思考、自學(xué)能力動(dòng)手能力強(qiáng),易于接受新事物。
寶劍鋒從磨礪出,梅花香自苦寒來。在大學(xué)四年中,憑著特有的堅(jiān)韌和執(zhí)著,我系統(tǒng)學(xué)習(xí)了可編程控制器及其系統(tǒng),自動(dòng)控制理論,電力電子技術(shù),單片機(jī)原理及應(yīng)用,模擬電子技術(shù),C語言編程,自動(dòng)化儀表與過程控制;通過四年的大學(xué)本科教育,培養(yǎng)了我良好的道德修養(yǎng)、綜合素質(zhì)和創(chuàng)新能力;品行端正,積極上進(jìn)。此間,參加過多次課程設(shè)計(jì)和實(shí)習(xí),使自己的動(dòng)手能力有了很大的提高,也讓我進(jìn)一步鞏固和掌握了專業(yè)知識(shí)。我已能夠較好地勝任電子電路設(shè)計(jì),生產(chǎn)線的控制與維護(hù)等方面的技術(shù)性及管理性工作。我真心的希望能從事和參與這方面的工作,我相信執(zhí)著的追求和永不幻滅的熱情是最好的工作動(dòng)力。同時(shí),為了拓寬知識(shí)面,我閱讀了大量的課外書籍,因此我有很強(qiáng)的文字組織能力和語言表達(dá)能力。
在不斷求索的人生歷程中,我逐步形成了“以誠待人、以理服人、以德感人”的品格?!白孕哦豢癜?穩(wěn)重但又熱情,年輕而富有朝氣”是我的特點(diǎn)。工作中,我盡心盡職、兢兢業(yè)業(yè)、克己奉公;學(xué)習(xí)上,我刻苦鉆研、敢于求索、敢于創(chuàng)新;生活上,我克勤克儉、吃苦耐勞、樂觀豁達(dá)。我性格開朗,愛好廣泛,富有熱情,相信一定能在工作中與同事相處融洽,營造一種愉快而高效的工作氛圍。而且在大學(xué)期間,我還多次參加勤工助學(xué),有豐富的工作和社會(huì)經(jīng)驗(yàn)。在努力學(xué)習(xí)和自我充實(shí)的同時(shí),我也贏得了老師和同學(xué)的好評(píng)。因此我希望能夠加入貴單位.我會(huì)踏踏實(shí)實(shí)地做好屬于自己的每一份工作,竭盡全力在工作中取得好的成績.如果您給我一個(gè)發(fā)展的機(jī)會(huì),我會(huì)以一顆真誠的心、飽滿的工作熱情、勤奮務(wù)實(shí)的工作作風(fēng)、快速高效的工作效率回報(bào)貴單位。即使貴單位認(rèn)為我還不符合你們的條件,我也將一如既往地關(guān)注貴單位的發(fā)展,并在此致以最誠摯的祝愿。感謝您的關(guān)注,期待您的答復(fù)!
此致
敬禮!
-----吃苦趁年輕,用我的行動(dòng)體現(xiàn)我的價(jià)值-----------------------------
第三篇:《電氣工程及其自動(dòng)化專業(yè)英語翻譯》第二節(jié)電路元件
第二節(jié) 電路元件
電路僅僅是元件之間的相互結(jié)合。我們發(fā)現(xiàn)電路中存在有兩種元件:無源元件和有源元件。有源元件能夠產(chǎn)生能量而無源元件卻不能,無源元件有電阻、電容和電感器等。最重要的有源元件是通常向與它們相連的電路釋放能量的電壓和電流源。
獨(dú)立源
一個(gè)理想的獨(dú)立源是產(chǎn)生完全獨(dú)立于其它電路變量的特定電壓或電流的有源元件。一個(gè)獨(dú)立電壓源是一個(gè)二端口元件,如一個(gè)電池或一臺(tái)發(fā)電機(jī),它們?cè)谄涠瞬烤S持某個(gè)特定的電壓。該電壓完全獨(dú)立于流過元件的電流,在其端部具有u伏電壓的電壓源的符號(hào)如圖1-4(a)所示,極性如圖所示,它表明a端比b端高u伏。如果u>0,那么a端的電位高于b端,當(dāng)然,如果u<0,反之亦然。
在圖1-4(a)中,電壓u可以是隨時(shí)間而變化,或者可以是恒定的,在這種情況下我們可能把它標(biāo)為U,對(duì)于恒定電壓源我們通常使用另一種符號(hào),例如在兩端只有U伏電壓的電池組,如圖1-4(b)所示。在恒定源的情況下我們可以交替地使用于圖1-4(a)或圖1-4(b)。
我們可能已經(jīng)注意到這一點(diǎn),即圖1-4(b)中的極性標(biāo)號(hào),是多余的因?yàn)槲覀兛梢愿鶕?jù)長天線的位置符,確定電池極性。
一個(gè)獨(dú)立電流源是二端元件在兩端之間特定的電流流過,該電流完全獨(dú)立于元件兩端的電壓,一個(gè)獨(dú)立電流源的符合如圖1-5所示。圖中i是特定電流,該電流的方向由箭頭標(biāo)明。
獨(dú)立源通常指的是向外電路釋放功率而非吸收功率,因此如果u是電源兩端的電壓而電流i直接從其正端流出,那么該電源正在向?qū)﹄娐丰尫殴β剩墒絧=ui算出。否則它就在吸收功率。例如圖1-6(a)中電池正在向外電路釋放功率24w,在圖1-6(b)中,電池就在充電情況,吸收功率24w。
受控源
一個(gè)理想的受控源是一個(gè)有源元件,它的電源量是由另外一個(gè)電壓和電流所控制。
受控源通常用菱形符號(hào)表明,如圖1-7所示。由于控制受控源的控制量來自于電路中其他元件的電壓或電流,同時(shí)由于受控源可以是電壓源或電流源。由此可以推出四種可能的受控源類型,即
電壓控制電壓源(VCVS)
電流控制電壓源(CCVS)
電壓控制電流源(VCCS)
電流控制電流源(CCCS)
受控源在模擬諸如晶體管、運(yùn)算放大器以及集成電路這些元件時(shí)是很有用的。應(yīng)該注意的是:一個(gè)理想電壓源(獨(dú)立或受控)可向電路提供以保證其端電壓為規(guī)定值所需的任意電流,而電流源可向電路提供以保證其電流為規(guī)定值所必須的電壓。還應(yīng)當(dāng)注意的是電源不僅向電路提供功率,他們也可從電路吸收功率。對(duì)于一個(gè)電壓源來說,我們知道的是由其提供或所獲得的電壓而非電流,同理,我們知道電流源所提供的電流而非電流源兩端的電壓。
第四篇:電氣工程及其自動(dòng)化專業(yè)英語翻譯
Electric Power Systems.The modern society depends on the electricity supply more heavily than ever before.It can not be imagined what the world should be if the electricity supply were interrupted all over the world.Electric power systems(or electric energy systems), providing electricity to the modern society, have become indispensable components of the industrial world.The first complete electric power system(comprising a generator, cable, fuse, meter, and loads)was built by Thomas Edison – the historic Pearl Street Station in New York City which began operation in September 1882.This was a DC system consisting of a steam-engine-driven DC generator supplying power to 59 customers within an area roughly 1.5 km in radius.The load, which consisted entirely of incandescent lamps, was supplied at 110 V through an underground cable system..Within a few years similar systems were in operation in most large cities throughout the world.With the development of motors by Frank Sprague in 1884, motor loads were added to such systems.This was the beginning of what would develop into one of the largest industries in the world.In spite of the initial widespread use of DC systems, they were almost completely superseded by AC systems.By 1886, the limitations of DC systems were becoming increasingly apparent.They could deliver power only a short distance from generators.To keep transmission power losses(I 2 R)and voltage drops to acceptable levels, voltage levels had to be high for long-distance power transmission.Such high voltages were not acceptable for generation and consumption of power;therefore, a convenient means for voltage transformation became a necessity.The development of the transformer and AC transmission by L.Gaulard and JD Gibbs of Paris, France, led to AC electric power systems.In 1889, the first AC transmission line in North America was put into operation in Oregon between Willamette Falls and Portland.It was a single-phase line transmitting power at 4,000 V over a distance of 21 km.With the development of polyphase systems by Nikola Tesla, the AC system became even more attractive.By 1888, Tesla held several patents on AC motors, generators, transformers, and transmission systems.Westinghouse bought the patents to these early inventions, and they formed the basis of the present-day AC systems.In the 1890s, there was considerable controversy over whether the electric utility industry should be standardized on DC or AC.By the turn of the century, the AC system had won out over the DC system for the following reasons:
(1)Voltage levels can be easily transformed in AC systems, thus
providing the flexibility for use of different voltages for generation, transmission, and consumption.(2)AC generators are much simpler than DC generators.(3)AC motors are much simpler and cheaper than DC motors.The first three-phase line in North America went into operation in 1893
——a 2,300 V, 12 km line in southern California.In the early period of AC power transmission, frequency was not standardized.This poses a problem for interconnection.Eventually 60 Hz was adopted as standard in North America, although 50 Hz was used in many other countries.The increasing need for transmitting large amounts of power over longer distance created an incentive to use progressively high voltage levels.To avoid the proliferation of an unlimited number of voltages, the industry has standardized voltage levels.In USA, the standards are 115, 138, 161, and 230 kV for the high voltage(HV)class, and 345, 500 and 765 kV for the extra-high voltage(EHV)class.In China, the voltage levels in use are 10, 35, 110 for HV class, and 220, 330(only in Northwest China)and500 kVforEHVclass.Thefirst750kVtransmission line will be built in the near future in Northwest China.With the development of the AC/DC converting equipment, high voltage DC(HVDC)transmission systems have become more attractive and economical in special situations.The HVDC transmission can be used for transmission of large blocks of power over long distance, and providing an asynchronous link between systems where AC interconnection would be impractical because of system stability consideration or because nominal frequencies of the systems are different.The basic requirement to a power system is to provide an uninterrupted energy supply to customers with acceptable voltages and frequency.Because electricity can not be massively stored under a simple and economic way, the production and consumption of electricity must be done simultaneously.A fault or misoperation in any stages of a power system may possibly result in interruption of electricity supply to the customers.Therefore, a normal continuous operation of the power system to provide a reliable power supply to the customers is of paramount importance.Power system stability may be broadly defined as the property of a power system that enables it to remain in a state of operating equilibrium under normal operating conditions and to regain an acceptable state of equilibrium after being subjected to a disturbance..Instability in a power system may be manifested in many different ways depending on the system configuration and operating mode.Traditionally, the stability problem has been one of maintaining synchronous operation.Since power systems rely on synchronous machines for generation of electrical power, a necessary condition for satisfactory system operation is that all synchronous machines remain in synchronism or, colloquially “in step”.This aspect of stability is influenced by the dynamics of generator rotor angles and power-angle relationships, and then referred to “ rotor angle stability ”
譯文:
電力系統(tǒng)
現(xiàn)代社會(huì)比以往任何時(shí)候更多地依賴于電力供應(yīng)。如果世界各地電力供應(yīng)中斷了,無法想象世界會(huì)變成什么樣。電力系統(tǒng)(或電力能源系統(tǒng)),提供電力到現(xiàn)代社會(huì),已成為產(chǎn)業(yè)界不可缺少的組成部分。歷史上第一個(gè)完整的電力系統(tǒng)(包括發(fā)電機(jī),電纜,熔斷器,計(jì)量,加載)由托馬斯愛迪生所建——紐約市珍珠街電站,始于1882年9月運(yùn)作。這是一個(gè)直流系統(tǒng)組成蒸汽發(fā)動(dòng)機(jī)驅(qū)動(dòng)的直流發(fā)電機(jī),供電范圍面積約1.5公里,送給59個(gè)客戶。他們的負(fù)載,其中包括白熾燈,通過地下電纜系統(tǒng)提供110V電壓。一個(gè)個(gè)類似的系統(tǒng)在世界各地大多數(shù)大城市運(yùn)行了數(shù)年。隨著弗蘭克斯普拉格在1884年對(duì)馬達(dá)的發(fā)展,電機(jī)負(fù)載被添加到這些系統(tǒng),從此開始發(fā)展成為世界上最大的產(chǎn)業(yè)之一。最初的直流系統(tǒng)被廣泛使用,盡管如此,他們幾乎完全被交流系統(tǒng)所取代。到1886年,直流系統(tǒng)的局限性也日益明顯。他們從發(fā)電機(jī)提供功率只有很短的距離。
為了保持發(fā)射功率損失(I 2 R)和電壓下降到可接受的水平,長途輸電電壓必須高。如此高的電壓發(fā)電和電力消耗是可以接受的,因此,電壓轉(zhuǎn)換有一個(gè)方便的手段成為了必要。法國的L.巴黎戈拉爾和JD吉布斯發(fā)展了變壓器和交流輸電并引領(lǐng)了交流電力系統(tǒng)。1889年,在北美波特蘭和威拉梅特大瀑布之間的俄勒岡州第一次實(shí)施交流傳輸線。這是一個(gè)單相線路傳輸為4,000伏,超過21公里距離的系統(tǒng)。隨著交流的發(fā)展多相系統(tǒng)由尼古拉特斯拉,成為更具吸引力的。在1888年,尼古拉特斯拉取得多項(xiàng)交流專利,包括電動(dòng)機(jī),發(fā)電機(jī),變壓器和輸電系統(tǒng)。西屋公司購買了這些早期的發(fā)明專利,并形成了現(xiàn)在交流系統(tǒng)的基礎(chǔ)。19世紀(jì)90年代,有很大的爭(zhēng)議在于直流或交流電力行業(yè)是否應(yīng)該統(tǒng)一。到了世紀(jì)之交時(shí),下面的原因使交流系統(tǒng)贏過了直流系統(tǒng):
(1)交流系統(tǒng)電壓水平可以很容易地改變,從而提供了傳輸?shù)撵`活性,發(fā)電用不同的電壓和消費(fèi)。
(2)交流發(fā)電機(jī)比直流發(fā)電機(jī)簡單得多。
(3)交流電機(jī)的馬達(dá)比直流簡單且便宜得多。
首次三相交流電線1893年投產(chǎn)于北美南加州-1根 2300V,12公里長的線路。在電力傳輸初期交流頻率并不規(guī)范。有許多不同頻率在使用:25,50,60,125,和133赫茲。這對(duì)互連的問題。最后北美的60赫茲標(biāo)準(zhǔn)獲得通過,雖然
50赫茲在許多其他國家仍在使用。較長的距離越來越需要大量的電壓傳輸這激勵(lì)了他們逐步使用高壓。為了避免電壓增殖數(shù)值無限,業(yè)界標(biāo)準(zhǔn)了電壓水平。在美國,標(biāo)準(zhǔn)是115,138,161,和230千伏的高電壓(高壓)類,345,500和765千伏級(jí)的特高電壓(超高壓)。在中國,各級(jí)使用電壓為10,35,110級(jí)高壓,220,330(僅在西北)和500千伏超高壓類。第一個(gè)750 kVtransmission線將在不久的將來建在中國西北地區(qū)。隨著交流/直流轉(zhuǎn)換設(shè)備的發(fā)展,高壓直流(HVDC)傳輸系統(tǒng)已經(jīng)成為更具吸引力和經(jīng)濟(jì)性的特殊情況。高壓直流輸電可用于輸入大塊輸電和長距離輸電,并提供不同系統(tǒng)間的異步連接,因?yàn)樵诮涣髀?lián)網(wǎng)系統(tǒng)間是不切實(shí)際的,因?yàn)榉€(wěn)定考慮,或因?yàn)橄到y(tǒng)間不同的頻率?;疽蟮诫娫聪到y(tǒng)是提供一個(gè)客戶可接受的電壓和頻率不間斷的能源供應(yīng)。由于電力無法用簡單和經(jīng)濟(jì)的方法大量儲(chǔ)存,電力的生產(chǎn)和消費(fèi)必須同時(shí)進(jìn)行。系統(tǒng)在任何階段的故障或誤操作可能導(dǎo)致給客戶的電力供應(yīng)中斷。因此,一個(gè)正常的電力
系統(tǒng)能連續(xù)運(yùn)行提供可靠的電力供應(yīng)給客戶是至關(guān)重要的。電力系統(tǒng)穩(wěn)定,可廣泛定義為干擾財(cái)產(chǎn)的權(quán)力系統(tǒng),可繼續(xù)經(jīng)營的狀態(tài)下正常運(yùn)行的平衡條件和后向遭受恢復(fù)一個(gè)可以接受的平衡狀態(tài)。在電力系統(tǒng)的不穩(wěn)定可能會(huì)表現(xiàn)在經(jīng)營方式和多種不同的方式上,這取決于系統(tǒng)配置。傳統(tǒng)上,穩(wěn)定性問題一直是一個(gè)保持同步運(yùn)行最主要的問題。由于電力系統(tǒng)的發(fā)電電力,一個(gè)令人滿意的系統(tǒng)運(yùn)行的必要條件是,依靠同步電機(jī)都留在同步或通俗的“步驟”。這一方面是受穩(wěn)定的發(fā)電機(jī)轉(zhuǎn)子的動(dòng)態(tài)角度和功角的關(guān)系,然后提到“轉(zhuǎn)子角穩(wěn)定”。
第五篇:電氣工程及其自動(dòng)化專業(yè)
電氣工程及其自動(dòng)化專業(yè)
專業(yè)介紹 電氣工程及其自動(dòng)化的觸角伸向各行各業(yè),小到一個(gè)開關(guān)的設(shè)計(jì),大到宇航飛機(jī)的研究,都有它的身影。本專業(yè)生能夠從事與電氣工程有關(guān)的系統(tǒng)運(yùn)行、自動(dòng)控制、電力電子技術(shù)、信息處理、試驗(yàn)技術(shù)、研制開發(fā)、經(jīng)濟(jì)管理以及電子與計(jì)算機(jī)技術(shù)應(yīng)用等領(lǐng)域的工作,是寬口徑“復(fù)合型”高級(jí)工程技術(shù)人才。該領(lǐng)域?qū)Ω咚饺瞬诺男枨蠛艽?。?jù)估計(jì),隨著國外大企業(yè)的進(jìn)入,在這一專業(yè)領(lǐng)域?qū)⒊霈F(xiàn)很大缺口,那時(shí)很可能出現(xiàn)人才供不應(yīng)求的現(xiàn)象。
電氣工程及其自動(dòng)化專業(yè)對(duì)廣大考生有很強(qiáng)的吸引力,屬于熱門專業(yè),高考錄取分?jǐn)?shù)線往往要比其他專業(yè)方向高許多,造成這一情況的主要原因有:①就業(yè)容易,工作環(huán)境好,收入高;②名稱好聽,專業(yè)內(nèi)容對(duì)學(xué)生有吸引力; 社會(huì)宣傳和輿論導(dǎo)向?qū)ζ溆欣?。該專業(yè)方向有著非常好的發(fā)展前景,研究成果較容易向現(xiàn)實(shí)產(chǎn)品轉(zhuǎn)換,而且效益相當(dāng)可觀。他創(chuàng)造性的研究思路吸引著眾多考生,這里的確是展示他們才能的好地方。但是鑒于國內(nèi)現(xiàn)在的形式,考生在報(bào)考該專業(yè)的時(shí)候應(yīng)該注意以下兩點(diǎn):
(1)充分考慮自己的興趣。也許自己本來并不對(duì)該方向感興趣,但是許多人都說好,于是自己就“感興趣”了。這對(duì)以后的發(fā)展是很不利的,畢竟興趣是最好的老師。
(2)衡量自己的綜合素質(zhì)。電氣工程及自動(dòng)化專業(yè)需要具有扎實(shí)的數(shù)學(xué)、物理基礎(chǔ),較強(qiáng)的外語綜合能力,為今后能夠掌握并且靈活運(yùn)用專業(yè)知識(shí)做準(zhǔn)備。該專業(yè)方向的人才需求雖然大,但可供選擇的人也很多,如果沒有非常強(qiáng)的綜合素質(zhì),很難在眾人之中脫穎而出,取得突出成績。
主干學(xué)科和課程
主干學(xué)科:電氣工程、控制科學(xué)與工程、計(jì)算機(jī)科學(xué)與技術(shù)
主要課程:電路理論、電子技術(shù)、電力電子技術(shù)、自動(dòng)控制原理、微機(jī)原理與應(yīng)用、電氣工程基礎(chǔ)、電機(jī)學(xué)、電器學(xué)、電力系統(tǒng)分析、電機(jī)設(shè)計(jì)、高低壓電器、電機(jī)控制、智能化電器原理與應(yīng)用、電力系統(tǒng)繼電保護(hù)、電力系統(tǒng)綜合自動(dòng)化、建筑供配電等。
培養(yǎng)目標(biāo)
培養(yǎng)適應(yīng)社會(huì)主義建設(shè)需要、德智體美全面發(fā)展,獲得工程師基本訓(xùn)練,能理論聯(lián)系實(shí)際、具備電工技術(shù)、電子技術(shù)、控制理論、自動(dòng)檢測(cè)與儀表、信號(hào)處理、計(jì)算機(jī)技術(shù)與應(yīng)用和網(wǎng)絡(luò)技術(shù)等較寬廣領(lǐng)域的工程技術(shù)基礎(chǔ)和一定的專業(yè)知識(shí),能在運(yùn)動(dòng)控制、工業(yè)過程控制、電力電子技術(shù)、檢測(cè)與自動(dòng)化儀表、電子與計(jì)算機(jī)技術(shù)、信息處理、管理與決策等領(lǐng)域研究、分析、設(shè)計(jì)、制造和應(yīng)用開發(fā)的應(yīng)用型高級(jí)工程技術(shù)人才。
培養(yǎng)要求
本專業(yè)學(xué)生主要學(xué)習(xí)電工技術(shù)、電子技術(shù)、信息控制、計(jì)算機(jī)技術(shù)、電氣工程及自動(dòng)化技術(shù)等方面較寬廣的工程技術(shù)基礎(chǔ)和一定的專
業(yè)知識(shí),使學(xué)生受到電工電子、信息控制及計(jì)算機(jī)技術(shù)方面的基本訓(xùn)練,以及電氣工程及自動(dòng)化領(lǐng)域的專業(yè)訓(xùn)練,具有解決電氣工程技術(shù)與控制技術(shù)問題的基本能力
學(xué)科特點(diǎn)
電氣工程及其自動(dòng)化專業(yè)是為各行各業(yè)培養(yǎng)能夠從事電氣工程及其自動(dòng)化、計(jì)算機(jī)技術(shù)應(yīng)用、經(jīng)濟(jì)管理等領(lǐng)域工作的寬口徑、復(fù)合型的高級(jí)工程技術(shù)人才。
該專業(yè)的特色體現(xiàn)在:強(qiáng)電與弱電相結(jié)合,電工技術(shù)與電子技術(shù)相結(jié)合,軟件與硬件相結(jié)合,元件與系統(tǒng)相結(jié)合,使學(xué)生獲得電氣控制、電力系統(tǒng)自動(dòng)化、電氣自動(dòng)化裝置及計(jì)算機(jī)應(yīng)用技術(shù)等領(lǐng)域的基本技能,具有分析和解決電氣工程技術(shù)領(lǐng)域技術(shù)問題的能力。就業(yè)方向 電氣工程及其自動(dòng)化,在當(dāng)時(shí)電氣控制發(fā)展迅速的背景下,就業(yè)狀況與機(jī)械等一樣,優(yōu)勢(shì)很大,就業(yè)范圍廣闊。絕對(duì)是個(gè)專業(yè)性很強(qiáng)的專業(yè),不過因?qū)W校不同,它的偏重也不一樣,有強(qiáng)弱電之分,這個(gè)你首先要分清楚,一般主學(xué)電力系統(tǒng)分析,電機(jī)學(xué),繼電保護(hù),電網(wǎng)等的為強(qiáng)電,這個(gè)方向的電氣專業(yè)因?yàn)殡娏π袠I(yè)的發(fā)展而變的非常吃香,但是有這個(gè)方向大學(xué)并不多,大多數(shù)大學(xué)的電氣專業(yè)都是以弱電為主。
強(qiáng)電:這個(gè)方向的最好的去向個(gè)人認(rèn)為是各地區(qū)的電力公司以及各大型電廠,至于這個(gè)行業(yè)的好壞我想我也就不必多說了,還有就是
一些大型外企,如:西門子,ABB等都是這個(gè)專業(yè)的消化大戶;
弱電:對(duì)于弱電來說,因?yàn)槠湟话闫蚩刂疲匀粝脒M(jìn)電力行業(yè)一般進(jìn)電廠比較多,電力公司相對(duì)招的人就很少了,至于其它方面與強(qiáng)電相差就比較少了,也可進(jìn)西門子,ABB等大型外企,以及國內(nèi)幾家大型的電氣公司。
本專業(yè)培養(yǎng)的學(xué)生可以從事下列工作:
1、電機(jī)電器設(shè)計(jì)、制造、控制、試驗(yàn)、運(yùn)行維護(hù)、研制開發(fā)、生產(chǎn)管理工作;或電力系統(tǒng)與電氣裝備的運(yùn)行、供電系統(tǒng)和高層建筑的電氣設(shè)計(jì)與運(yùn)行維護(hù)工作;或建筑電氣領(lǐng)域電氣設(shè)計(jì)、樓宇自動(dòng)化、綜合布線與智能建筑的系統(tǒng)設(shè)計(jì)、系統(tǒng)運(yùn)行、研制開發(fā)、試驗(yàn)分析、工程建設(shè)與管理工作。
2、電力電子、電氣傳動(dòng)、自動(dòng)化、儀表等技術(shù)領(lǐng)域的研制開發(fā)工作。業(yè)務(wù)范圍
1、自動(dòng)控制系統(tǒng)、電力電子設(shè)備設(shè)計(jì)、制造、測(cè)試等工作。
2、自動(dòng)化技術(shù)的理論研究及科學(xué)實(shí)驗(yàn)方面的工作。
3、計(jì)算機(jī)測(cè)控技術(shù)和科研開發(fā)工作。
4、工廠控制系統(tǒng)及設(shè)備的技術(shù)開發(fā)、應(yīng)用和管理工作。
5、學(xué)校的教學(xué)、科研和管理工作。
就業(yè)前景
電氣工程及其自動(dòng)化專業(yè)培養(yǎng)的畢業(yè)生就業(yè)面寬、適應(yīng)性強(qiáng)。該專業(yè)的畢業(yè)生主要面向電力行業(yè)就業(yè),可從事電力設(shè)計(jì)、建設(shè)、調(diào)試、生產(chǎn)、運(yùn)行、市場(chǎng)運(yùn)營、科技開發(fā)和技術(shù)培訓(xùn)等工作,也可從事其他
行業(yè)中的電氣技術(shù)工作。主要就業(yè)單位有電力公司、電力設(shè)計(jì)院、電力規(guī)劃院、電力建設(shè)部門、電力生產(chǎn)單位、電氣工程研究開發(fā)公司和研究院以及具有電氣相關(guān)專業(yè)的院校。自動(dòng)控制、電力電子技術(shù)、信息處理、試驗(yàn)分析、研制開發(fā)、經(jīng)濟(jì)管理以及電子與計(jì)算機(jī)技術(shù)應(yīng)用等領(lǐng)域的工作,電氣自動(dòng)化專業(yè)就業(yè)前景怎樣:
1,電業(yè)局
2,設(shè)計(jì)院
3,工程局
最好的是電業(yè)局。福利好,待遇高。然后是設(shè)計(jì)院,工作相對(duì)比較輕松。最艱苦的是工程局。因?yàn)橐S著工程地點(diǎn)到處跑。但是工資也不低。總的來說是很不錯(cuò)的。而且還可以向自動(dòng)化、電子等方向轉(zhuǎn)行。這個(gè)專業(yè),強(qiáng)電,弱電都有的。
“自動(dòng)化”一是屬于信息產(chǎn)業(yè)。信息產(chǎn)業(yè)被人們譽(yù)為“朝陽產(chǎn)業(yè)”,發(fā)展快、需要人才多、待遇高,是當(dāng)今科技發(fā)展的趨勢(shì)所在。因此,作為信息產(chǎn)業(yè)中的重要一員,自動(dòng)化專業(yè)同樣有著光輝的前途。二是自動(dòng)化應(yīng)用范圍廣。幾乎所有的工業(yè)部門都可以同自動(dòng)控制掛上鉤,現(xiàn)代化的農(nóng)業(yè)、國防也都與自動(dòng)化息息相關(guān)。三是本專業(yè)對(duì)于個(gè)人發(fā)展非常有利。本專業(yè)課程設(shè)置的覆蓋面廣,所學(xué)的東西與其他學(xué)科交叉甚多。這也與本專業(yè)的來歷有關(guān),自動(dòng)化專業(yè)大部分源于計(jì)算機(jī)或者電子工程系的自動(dòng)控制專業(yè)。
隨著我國經(jīng)濟(jì)的不斷發(fā)展,現(xiàn)代化工業(yè)的不斷發(fā)展使電氣自動(dòng)化技術(shù)方面的人才市場(chǎng)有著相當(dāng)大的潛力。尤其是廣東地區(qū),自動(dòng)化生
產(chǎn)技術(shù)不斷提高,自動(dòng)化產(chǎn)品不斷普及,智能樓宇和智能家居的應(yīng)用,智能交通的不斷發(fā)展,為電氣自動(dòng)化技術(shù)專業(yè)提供了廣闊的發(fā)展前景。
通常情況下,畢業(yè)生可以選擇國有的質(zhì)量技術(shù)監(jiān)督部門、研究所、工礦企業(yè)等;也可以是一些外資、私營企業(yè),待遇當(dāng)然是相當(dāng)可觀的。