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中文題目:煤礦采區(qū)移動變電站供電系統(tǒng)設計
外文題目:COAL MINING AREA MOBILE SUSTATION POWER
SUPPLY SYSTEM DESIGN
畢業(yè)設計(論文)共 60頁(其中:外文文獻及譯文 12 頁)圖紙共 1張
完成日期20xx年6月 答辯日期20xx年6月
附錄A
General Requirements to Construction of Substation
Substations are a vital element in a power supply system of industrial enterprises.They serve to receive ,convert and distribute electric energy .Depending on power and purpose ,the substations are divided into central distribution substations for a voltage of 110-500kV;main step-down substations for110-220/6-10-35kV;deep entrance substations for 110-330/6-10Kv;distribution substations for 6-10Kv;shop transformer substations for 6-10/0.38-0.66kV.At the main step-down substations, the energy received from the power source is transformed from 110-220kV usually to 6-10kV(sometimes 35kV) which is distributed among substations of the enterprise and is fed to high-voltage services.
Central distribution substations receive energy from power systems and distribute it (without or with partial transformation) via aerial and cable lines of deep entrances at a voltage of 110-220kV over the enterprise territory .Central distribution substation differs from the main distribution substation in a higher power and in that bulk of its power is at a voltage of 110-220kV;it features simplified switching circuits at primary voltage; it is fed from the power to an individual object or region .Low-and medium-power shop substations transform energy from 6-10kV to a secondary voltage of 380/220 or 660/380.
Step-up transformer substations are used at power plants for transformation of energy produced by the generators to a higher voltage which decreases los ses at a long-distance transmission .Converter substations are intended to convert AC to DC (sometimes vice versa) and to convert energy of one frequency to another .Converter substations with semiconductor rectifiers are convert energy of one frequency to another .Converter substations with semiconductor rectifiers are most economic. Distribution substations for 6-10kV are fed primarily from main distribution substations (sometimes from central distribution substations).With a system of dividing
substations for 110-220kV, the functions of a switch-gear are accomplishedby switch-gears for 6-10kV at deep entrance substations.
Depending on location of substations their switch-gear may be outdoor or indoor. The feed and output lines at 6-10kV substations are mainly of the cable type .at 35-220kV substations of the aerial type .When erecting and wiring the substations ,major attention is given to reliable and economic power supply of a given production.
Substations are erected by industrial methods with the use of large blocks and assemblies prepared at the site shops of electric engineering organizations and factories of electrical engineering industry .Substations are usually designed for operation without continuous attendance of the duty personnel but with the use of elementary automatic and signaling devices.
When constructing the structural part of a substation .it is advisable to use light-weight industrial structures and elements (panels ,floors ,etc.) made of bent sections .These elements are pre-made outside the erection zone and are only assembled at site .This considerably cuts the terms and cost of construction.
Basic circuitry concepts of substations are chosen when designing a powersupply system of the enterprise .Substations feature primary voltage
entrances .transformers and output cable lines or current conductors of secondary voltage Substations are mounted from equipment and elements described below .The number of possible combinations of equipment and elements is very great .Whenelaborating a substation circuitry ,it is necessary to strive for maximum simplification and minimizing the number of switching devices .Such substations are more reliable and economic .Circuitry is simplified by using automatic reclosure or automatic change over to reserve facility which allows rapid and faultless redundancy of individual elements and using equipment.
When designing transformer substations of industrial enterprises for all voltages , the following basic considerations are taken into account:
1.Preferable employment of a single-bus system with using two-bus systems only to ensure a reliable and economic power supply;
2.Wide use of unitized constructions and busless substations;
3.Substantiated employment of automatics and telemetry ;if the substation design does not envisage the use of automatics or telemetry ,the circuitry is so arranged as to allow for adding such equipment in future without excessive investments and re-work.
4.Use of simple and cheap devices-isolating switches ,short-circuiting switches ,load-breaking isolators ,fuses ,with due regard for their switching capacity may drastically cut the need for expensive and critical oil ,vacuum ,solenoid and air switches .Substation and switch-gear circuitries are so made that using the equipment of each production line is fed from individual transformers ,assemblies ,the lines to allow their disconnection simultaneously with mechanisms without disrupting operation of adjacent production flows.
When elaborating circuitry of a substation, the most vital task is to properly choose and arrange switching devices(switches ,isolators ,current limiters ,arre sters ,high-voltage fuses).The decision depends on the purpose ,power and significance of the substation.
Many years ago, scientists had very vague ideas about electricity. Many of them thought of it as a sort of fluid that flowed through wires as water flows through pipes, but they could not understand what made it flow. Many of them felt that electricity was made up of tiny particles of some kind ,but trying to separate electricity into individual particles baffled them.
Then, the great American scientist Millikan, in 1909,astounded the scientific world by actually weighing a single particle of electricity and calculating its electric charge. This was probably one of the most delicate weighing jobs ever done by man,for a single electric particle weighs only about half of a millionth of a pound. To make up a pound it would take more of those particles than there are drops of water in the Atlantic Ocean.
They are no strangers to us, these electric particles, for we know them as electrons.When large numbers of electrons break away from their atoms and move through a wire,we describe this action by saying that electricity is flowing through the wire.Yes,the electrical fluid that early scientists talked about is nothing more than
electrical flowing along a wire.
But how can individual electrons be made to break away from atoms? And how canthese free electrons be made to along a wire? The answer to the first question lies in the structure of the atoms themselves. Some atoms are so constructed that they lose electrons easily. An atom of copper, for example ,is continually losing an electron, regaining it(or another electron),and losing it again. A copper atom normally has 29 electrons, arranged in four different orbits about its nucleus. The inside orbit has 2 electrons. The next larger orbit has 8.The third orbit is packed with 18 electrons . And the outside orbit has only one electron.It is this outside electron that the copper atom is continually losing, for it is not very closely tied to the atom. It wanders off, is replaced by another free-roving electron, and then this second electron also wanders away.
Consequently,in a copper wire free electrons are floating around in all directions among the copper atoms.Thus, even through the copper wire looks quite motionless to your ordinary eye, there is a great deal of activity going on inside it. If the wire were carrying electricity to an electric light or to some other electrical device, the electrons would not be moving around at random. Instead, many of them would be rushing in the same direction-from one end of the wire to the other.
This brings us to the second question .How can free electrons be made to move along a wire? Well ,men have found several ways to do that .One way is chemical. Volta,s voltaic pile,or battery, is a chemical device that makes electricity(or electrons)flow in wires. Another way is magnetic. Faraday and Henry discovered how magnets could be used to make electricity flow in a wire.
Magnets
Almost everyone has seen horseshoe magnets-so called because they are shaped like horseshoes. Probably you have experimented with a magnet, and noticed how it will pick up tacks and nails, or other small iron objects. Men have known about magnets for thousands of years.
Several thousand years ago, according to legend, a shepherd named Magnes lived on the island of Crete, in the Mediterranean Sea .He had a shepherds crook tipped with iron. One day he found an oddly shaped black stone that stuck to this iron tip.Later, when many other such stones were found, they were called magnets(after Magnets).These were natural magnets.
In recent times men have learned how to make magnets out of iron. More important still, they have discovered how to use magnets to push electrons through wires-that is, how to make electricity flow. Before we discuss this, there arecertain characteristics of magnets that we should know about.If a piece of glass is laid on top of a horse- shoes magnet, and if iron filings are then sprink ledon the glass, the filings will arrange themselves into lines. If this same thing is trid with a bar magnet(a horseshoe magnet straightened out),the lines can be seen more easily. These experiments demonstrate what scientists call magnetic lines of force. Magnets, they explain, work through lines of force that ext- end between the two ends of the magnet. But electrons seem to have magnetic lines of force around them, too.This can be proved by sticking a wire through a piece ofcard board, sprinkling iron filings on the cardboard, and connecting a battery to the wire. The filings will tend to form rings around the wire,as a result of the magnetism of the moving electrons(or electricity).So we can see that there is arelationship between moving electrons and magnetism, Magnetism results from the movement of electrons.
Of course, electrons are not really flowing in the bar magnet, but they are in motion, circling the nuclei of the iron atoms. However, in the magnet, circling thelined up in such a way that their electrons are circling in the same direction. Perhaps a good comparison might be a great number of boys whirling balls onstrings in a clockwise direction around their heads.
附錄B
變電站(所)在電源系統(tǒng)的工業(yè)企業(yè)是一個至關重要的因素。他們接收,轉換和發(fā)送電能。根據(jù)能源和需求,變電站分為中央配電變電站電壓為110-500kV;主要降壓變電所電壓為110-220/6-10-35kV; 深入口變電站為110-330/6-10kV;
二變電站的電壓為6-10Kv;車間變電所電壓為;中央配電變電站從電力系統(tǒng)接收能量并分發(fā)它(不包括;升壓變壓器變電站用于將電廠產(chǎn)生的能量轉化使發(fā)電機;根據(jù)變電站變的位置,電站設備在可以露天或室內(nèi);用工業(yè)的方式建設變電站,是使用大量的數(shù)塊和在電氣;當建立變電站結構的一部分,應當采用薄型建造結構以;變電站基本電路概念設計的選擇,是根據(jù)企業(yè)的供電系;當設計工業(yè)企業(yè)二次變電站的電壓為6-10Kv;車間變電所電壓為6-10/0.38-0.66kV。在主要的降壓變電所,電源能量轉化電壓為110-220kV,通常使用6-10Kv(有時為35kV變電所)的電壓分配給企業(yè)和被用來滿足高壓服務。
中央配電變電站從電力系統(tǒng)接收能量并分發(fā)它(不包括或者包括部分變換) 給企業(yè)不同區(qū)域,通過空中電纜和地下電纜線路電壓為110-220kV。 中央分配變電站站不同于主配電變電它是一個更強大的電力設施,它的電壓大部分在110-220kV的電壓。它可以簡化初級電壓、中級電壓或地區(qū)的開關電路。中低級別變電站改造能量來自6-10kv的電壓,它的二次側電壓為380/220或660/380。
升壓變壓器變電站用于將電廠產(chǎn)生的能量轉化使發(fā)電機產(chǎn)生的電壓升高,從而有效地減少在遠距離輸電能量的損失轉換器變電站的目的是為了將直流轉換成交流(有時相反)和轉換成能量時改變頻率。轉換器變電站的能量轉換是用半導體整流器來變頻的。帶半導體整流器的轉化器變電站是最經(jīng)濟的。6-10kV的配電變電站主要依據(jù)主配電變電站(有時依據(jù)中央配電變電站)。110-220kV變電站系統(tǒng)區(qū)域的劃分時,根據(jù)變電站設備功能劃分時是有學問的,6-10kV的變電站設備劃分在變電站的入口。
根據(jù)變電站變的位置,電站設備在可以露天或室內(nèi)。6-10kV變電站的在電纜的類型主要是供給輸出線。在35-220kV變電站空中線路樣式,在變電站架線和接線,主要注重供電生產(chǎn)的可靠和經(jīng)濟。
用工業(yè)的方式建設變電站,是使用大量的數(shù)塊和在電氣工程組織和工廠電氣工程等行業(yè)的車間的位置進行組裝。變電站通常是專為不連續(xù)操作的責任人員所設計,但用的是基本的自動設備和信號裝置。
當建立變電站結構的一部分,應當采用薄型建造結構以及由彎段組成的組件(板材、地板等)。這些元件是預先安裝區(qū)外面建造區(qū)域并且只是在這個位置組裝。這樣可以有效的削減變電所建造成本。
變電站基本電路概念設計的選擇,是根據(jù)企業(yè)的供電系統(tǒng)特點得到的。變電站電壓特性主要入口,變壓器和輸出電纜線路導線或當前導體的二次電壓.變電站安裝的設備和元件,設備和元件的若干種可能的組合是非常好的。當闡述了變電站的電路時爭取切換裝置最大的簡化和數(shù)目的最小化。這樣的變電站更可靠、經(jīng)濟。電路簡化是采用自動接入或自動轉入儲備的方法,允許快速和無錯誤的自
動接入每一個元件和使用設備。
當設計工業(yè)企業(yè)全電壓變電站時,下面的基本因素都要考慮在內(nèi)。
1.優(yōu)先使用采用兩編組的單總線系統(tǒng)可以確??煽康暮徒?jīng)濟的供應電力。
2.配套建設和變電站廣泛使用。
3.變電站使用自動化并且支持遙測技術;如果變電站的設計并不支持使用自動化或遙測、線路安而且不允許添加設備,確保以后沒有過度投資和返工。
4.使用簡單、便宜的裝置,有絕緣裝置的斷路器、短路開關、過載保護隔離器、保險絲,預期到他們的交換容量可考慮大幅度削減昂貴的器件需要和臨界油、真空、螺線管和空氣開關電路使用。變電站和開關電路,采用這樣的設備的每個生產(chǎn)線服從個體變壓器、裝配、允許他們同時的斷開而不破壞斷開連接的生產(chǎn)流程的機制的線條。
變電站的線路的意義,最重要的一點是要妥善安排與選擇轉換器件(開關、隔離者、電流限制器等、避雷器、高低壓熔斷器),這決定了變電站的目的、功能和意義。
很多年以前,科學家們對電仍只有很模糊的概念。他們之中不少人認為電是一種“流體”,這種流體就像水流經(jīng)管道一樣流過導線。但他們并不了解是什么東西使電流動。他們之中的許多人覺得電是有某種極小的微粒構成的,但試圖把電分離成單個的小顆粒他們卻束手無策。
此后,以為偉大的美國科學家密利坎于1909年,真正地稱出了單個的電粒子的重量并算出它的電荷而使科學界震驚不已。這可能是人類做過的最細致的計量工作之一,因為一個單個的電粒子的重量僅為一磅的百萬分之一,百萬分之一的一半左右的重量。要合成一磅重需要的電粒子數(shù)將要比大西洋的全部水的水滴數(shù)還要多。
這些電粒子,他們對我們并不陌生,因為我們知道他們就是電子。當大量電子擺脫原子跑出來并通過導線運動時,我們把這種現(xiàn)象說成是電通過導線“流動”。是的,早先的科學家所說的電的“流體”只不過是沿著導線流動的電子。
那么,如何能使一些單個的電子擺脫原子的束縛而跑出來呢?
而且,又怎樣能使這些自由電子沿導線運動呢?
第一個問題的答案就在于原子本身的結構上。某些原子的結構使他們很容易
失去電子。例如,一個銅原子在正常情況下有29個電子,它們排列在核子周圍的4個不同的軌道上。最里層的軌道上有2個電子。第二層較大的軌道上有8個電子。第三層軌道上擠滿18個電子。而外層軌道上只有一個電子。正是這個外層電子,銅原子不斷丟掉它,因為這個電子受原子的約束不那么緊。它忽而游離而去,并被另一游離的電子所替代,然后,這后一個電子也游離而去。
結果,在銅導線中自由電子在銅原子之間向四面八方漂浮。所以,盡管對你們的普通的肉眼來說,銅導線看來是完全不動的,但在它內(nèi)部卻不斷地進行著大量的活動。
如果導線把電輸送到一盞電燈或者另外某個電氣設備那里,這些電子就不會雜亂無章地到處跑來跑去,而是它們中的許多電子將會向一個方向奔去-從導線的一端奔向另一端。
這就把我們引向第二個問題,如何才能使自由電子沿導線運動呢?好啦,人們已經(jīng)找到幾種方法來做到這一點。一種就是化學方法。伏特電堆,或者叫電池,就是能使電流在導線中流動的一種化學裝置。另一種方法就是電磁法。法拉第和亨利發(fā)現(xiàn)了怎樣能把磁鐵用來使電在導線中流動的辦法。
磁鐵
幾乎每個人都見過馬蹄形磁鐵-之所以這樣叫他是因為他們的形狀做成馬蹄形的。可能你們都用磁鐵做過試驗,并且看到它是怎樣吸起按釘,小釘子或者其他一些小鐵件的。人們了解磁鐵已經(jīng)幾千年了。
據(jù)傳說,幾千年前有個名叫麥格尼斯的牧羊人住在地中海的克里特島上。他有一根牧羊人用的帶鐵頭的棍杖。一天,他發(fā)現(xiàn)一塊奇形怪狀的黑石頭黏在鐵頭上。后來,當又發(fā)現(xiàn)許多這種石頭時,人們就叫它們?yōu)榇盆F。這些就是天然磁鐵。
近年來,人們已經(jīng)掌握怎樣使用鐵來制成磁鐵。尤其重要的是,人們發(fā)現(xiàn)了如何使用磁鐵推動電子通過導線-也就是怎樣使電流動。
在我們討論這點之前,磁鐵有某些特性我們應當了解。如果把一塊玻璃放在馬蹄形磁鐵的端部,然后把一些鐵粉末撒在玻璃上,那么鐵粉自己就會排成許多線。如果用一根棒做的話,就更容易看出這些鐵粉排成的線條了。這些實驗演示了科學家們所謂的磁力線。他們解釋說。磁鐵通過磁鐵兩端之間延伸出來的磁力線起作用。
但是,在電子周圍似乎也有磁力線。把一根導線穿過一塊硬紙板,在紙板上撒上鐵粉,并把電池與導線連通在一起,這點就可以得到證明。由于運動的電子的磁性的結果,鐵粉就會繞導線周圍形成一些圓環(huán)。因此,我們可以看到,在運動者的電子和磁性之間有一種關系。磁性就是由電子的運動引起的。
當然,電子并不是在磁棒里真的“流動”,但它們卻是在運動,在繞鐵原子核做旋轉運動。然而,在磁鐵中,原子都排列的使它們的電子都向同一方向旋轉。也許可打一個恰當?shù)谋扔?,就像許多小孩在他們頭頂上以順時針方向甩動系在線上的小球一樣。
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學 號
指導教師
今年學期初,我參加了學校組織的畢業(yè)實習,在阜新百勝機械廠進行了參觀實習。實習過程中,我主要對變電所進行了進一步的學習。變電所就是電力系統(tǒng)中對電能的電壓和電流進行變換、集中和分配的場所。為保證電能的質(zhì)量以及設備的安全,在變電所中還需進行電壓調(diào)整、潮流(電力系統(tǒng)中各節(jié)點和支路中的電壓、電流和功率的流向及分布)控制以及輸配電線路和主要電工設備的保護。按用途可分為電力變電所和牽引變電所(電氣鐵路和電車用)。變電所由主接線,主變壓器,高、低壓配電裝置,繼電保護和控制系統(tǒng),所用電和直流系統(tǒng),遠動和通信系統(tǒng),必要的無功功率補償裝置和主控制室等組成。其中,主接線、主變壓器、高低壓配電裝置等屬于一次系統(tǒng);繼電保護和控制系統(tǒng)、直流系統(tǒng)、遠動和通信系統(tǒng)等屬二次系統(tǒng)。主接線是變電所的最重要組成部分。它決定著變電所的功能、建設投資、運行質(zhì)量、維護條件和供電可靠性。一般分為單母線、雙母線、一個半斷路器接線和環(huán)形接線等幾種基本形式。主變壓器是變電所最重要的設備,它的性能與配置直接影響到變電所的先進性、經(jīng)濟性和可靠性。一般變電所需裝2~3臺主變壓器;330千伏及以下時,主變壓器通常采用三相變壓器,其容量按投入5?~10年的預期負荷選擇。此外,對變電所其他設備選擇和所址選擇以及總體布置也都有具體要求。變電所繼電保護分系統(tǒng)保護(包括輸電線路和母線保護)和元件保護(包括變壓器、電抗器及無功補償裝置保護)兩類。變電所的控制方式一般分為直接控制和選控兩大類。前者指一對一的按紐控制。對于控制對較多的變電所,如采用直接控制方式,則控制盤數(shù)量太多,控制監(jiān)視面太大,不能滿足運行要求,此時需采用選控方式。選控方式具有控制容量大、控制集中、控制屏占地面積較小等優(yōu)點;缺點是直觀性較差,中間轉換環(huán)節(jié)多,不便使用。由于配電所是日常生產(chǎn)中非常重要的環(huán)節(jié),作為能量的直接輸出地,它的安全工作也是非常重要的。所以變電所要采取非常必要的防雷措施,大概有以下四點:(1)采用避雷針或避雷線對變壓器作防直擊雷保護;(2)采用閥型避雷器對變壓器作防雷電侵入波保護;(3)利用變壓器工作接地兼作避雷針和避雷器的防雷接;(4)將配電室進、出線處架空線絕緣子鐵腳與變電所工作接地體相連接作防雷電侵入波保護。通過這一次的實習,我了解了變電所電氣設備的構成、了解配電裝置的布置形式及特點,并了解安全凈距的意義。了解控制屏、保護屏的布置情況及主控室的總體布置情。在變電站工作,安全是最重要的一件事,所以我們牢記安全第一、預防為主的實習方針,加強安全學習,提高安全意識,更是我們的必修課。在這次實習中,我收益頗多,這些都是無形資產(chǎn),將伴隨我一生。
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注:實習結束時,由實習學生填寫本表后,交指導教師和實習單位簽署意見,最后交所在教學單位歸檔保管。