水輪機(jī)和水力發(fā)電文獻(xiàn)翻譯

1、<p><b>　　中文3840字</b></p><p><b>　　外文文獻(xiàn)：</b></p><p>　　hydraulicturbines and hydro-electric power</p><p><b>　　Abstract</b></p><p>

2、　　Power may be developed from water by three fundamental processes : by action of its weight, of its pressure, or of its velocity, or by a combination of any or all three. In modern practice the Pelton or impulse wheel i

3、s the only type which obtains power by a single process the action of one or more high-velocity jets. This type of wheel is usually found in high-head developments. Faraday had shown that when a coil is rotated in a magn

4、etic field electricity is generated. Thus, in order to produce</p><p>　　Keywords hydraulic turbines hydro-electric power classification of hydel plants</p><p>　　head scheme</p><p>

5、;　　There has been practically no increase in the efficiency of hydraulic turbines since about 1925, when maximum efficiencies reached 93% or more. As far as maximum efficiency is concerned, the hydraulic turbine has abou

6、t reached the practicable limit of development. Nevertheless, in recent years, there has been a rapid and marked increase in the physical size and horsepower capacity of individual units.</p><p>　　In additio

7、n, there has been considerable research into the cause and prevention of cavitation, which allows the advantages of higher specific speeds to be obtained at higher heads than formerly were considered advisable. The net e

8、ffect of this progress with larger units, higher specific speed, and simplification and improvements in design has been to retain for the hydraulic turbine the important place which it has long held at one of the most im

9、portant prime movers.</p><p>　　1. types of hydraulic turbines</p><p>　　Hydraulic turbines may be grouped in two general classes: the impulse type which utilizes the kinetic energy of a high-velo

10、city jet which acts upon only a small part of the circumference at any instant, and the reaction type which develops power from the combined action of pressure and velocity of the water that completely fills the runner a

11、nd water passages. The reaction group is divided into two general types: the Francis, sometimes called the reaction type, and the propeller type. The propell</p><p>　　1.1 impulse wheels</p><p>　

12、　With the impulse wheel the potential energy of the water in the penstock is transformed into kinetic energy in a jet issuing from the orifice of a nozzle. This jet discharge freely into the atmosphere inside the wheel h

13、ousing and strikes against the bowl-shaped buckets of the runner. At each revolution the bucket enters, passes through, and passes out of the jet, during which time it receives the full impact force of the jet. This prod

14、uces a rapid hammer blow upon the bucket. At the same time th</p><p>　　1.2 Francis runners</p><p>　　With the Francis type the water enters from a casing or flume with a relatively low velocity,

15、passes through guide vanes or gates located around the circumstance, and flows through the runner, from which it discharges into a draft tube sealed below the tail-water level. All the runner passages are completely fill

16、ed with water, which acts upon the whole circumference of the runner. Only a portion of the power is derived from the dynamic action due to the velocity of the water, a large part of the</p><p>　　1.3 propell

17、er runners</p><p>　　nherently suitable for low-head developments, the propeller-type unit has effected marked economics within the range of head to which it is adapted. The higher speed of this type of turbi

18、ne results in a lower-cost generator and somewhat smaller powerhouse substructure and superstructure. Propeller-type runners for low heads and small outputs are sometimes constructed of cast iron. For heads above 20 ft,

19、they are made of cast steel, a much more reliable material. Large-diameter propellers may hav</p><p>　　1.4 adjustable-blade runners</p><p>　　The adjustable-blade propeller type is a development

20、from the fixed-blade propeller wheel. One of the best-known units of this type is the Kaplan unit, in which the blades may be rotated to the most efficient angle by a hydraulic servomotor. A cam on the governor is used t

21、o cause the blade angle to change with the gate position so that high efficiency is always obtained at almost any percentage of full load.</p><p>　　By reason of its high efficiency at all gate openings, the

22、adjustable-blade propeller-type unit is particularly applicable to low-head developments where conditions are such that the units must be operated at varying load and varying head. Capital cost and maintenance for such u

23、nits are necessarily higher than for fixed-blade propeller-type units operated at the point of maximum efficiency.</p><p>　　2. thermal and hydropower</p><p>　　As stated earlier, the turbine blad

24、es can be made to run by the energy of fuels or flowing water. When fuel is used to produce steam for running the steam turbine, then the power generated is known as thermal power. The fuel which is to be used for genera

25、ting steam may either be an ordinary fuel such as coal, fuel oil, etc., or atomic fuel or nuclear fuel. Coal is simply burnt to produce steam from water and is the simplest and oldest type of fuel. Diesel oil, etc. may a

26、lso be used as fuels for </p><p>　　But, when the energy of the flowing water is used to run the turbines, then the electricity generated is called hydroelectric power. This scheme is known as hydro scheme, a

27、nd the power house is known as hydel power station or hydroelectric power station. In a hydro scheme, a certain quantity of water at a certain potential head is essentially made to flow through the turbines. The head cau

28、sing flow runs the turbine blades, and thus producing electricity from the generator coupled to turbine. In </p><p>　　3.classification of hydel plants</p><p>　　Hydro-plants may be classified on

29、the basis of hydraulic characteristics as follow: ① run-off river plants .②storage plants.③pumped storage plants.④tidal plants. they are described below.</p><p>　　Run-off river plants.</p><p>　　

30、These plants are those which utilize the minimum flow in a river having no appreciable pondage on its upstream side. A weir or a barrage is sometimes constructed across a river simply to raise and maintain the water leve

31、l at a pre-determined level within narrow limits of fluctuations, either solely for the power plants or for some other purpose where the power plant may be incidental. Such a scheme is essentially a low head scheme and m

32、ay be suitable only on a perennial river having sufficient d</p><p>　　Run-off river plants generally have a very limited storage capacity, and can use water only when it comes. This small storage capacity is

33、 provided for meeting the hourly fluctuations of load. When the available discharge at site is more than the demand (during off-peak hours ) the excess water is temporarily stored in the pond on the upstream side of the

34、barrage, which is then utilized during the peak hours.</p><p>　　he various examples of run-off the river pant are: Ganguwal and Kolta power houses located on Nangal Hydel Channel, Mohammad Pur and Pathri pow

35、er houses on Ganga Canal and Sarda power house on Sarda Canal.</p><p>　　The various stations constructed on irrigation channels at the sites of falls, also fall under this category of plants.</p><

36、p>　　(2) Storage plants</p><p>　　A storage plant is essentially having an upstream storage reservoir of sufficient size so as to permit, sufficient carryover storage from the monsoon season to the dry summ

37、er season, and thus to develop a firm flow substantially more than minimum natural flow. In this scheme, a dam is constructed across the river and the power house may be located at the foot of the dam such as in Bhakra,

38、Hirakud, Rihand projects etc. the power house may sometimes be located much away from the dam (on the downst</p><p>　　When the power house is located near the dam, as is generally done in the low head instal

39、lations ; it is known as concentrated fall hydroelectric development. But when the water is carried to the power house at a considerable distance from the dam through a canal, tunnel, or pen-stock; it is known as a divid

40、ed fall development.</p><p>　　(3) Pumped storage plants.</p><p>　　A pumped storage plant generates power during peak hours, but during the off-peak hours, water is pumped back from the tail wate

41、r pool to the headwater pool for future use. The pumps are run by some secondary power from some other plant in the system. The plant is thus primarily meant for assisting an existing thermal plant or some other hydel pl

42、ant.</p><p>　　During peak hours, the water flows from the reservoir to the turbine and electricity is generated. During off-peak hours, the excess power is available from some other plant, and is utilized fo

43、r pumping water from the tail pool to the head pool, this minor plant thus supplements the power of another major plant. In such a scheme, the same water is utilized again and again and no water is wasted.</p><

44、;p>　　For heads varying between 15m to 90m, reservoir pump turbines have been devised, which can function both as a turbine as well as a pump. Such reversible turbines can work at relatively high efficiencies and can h

45、elp in reducing the cost of such a plant. Similarly, the same electrical machine can be used both as a generator as well as a motor by reversing the poles. The provision of such a scheme helps considerably in improving t

46、he load factor of the power system.</p><p>　　(4) Tidal plants</p><p>　　Tidal plants for generation of electric power are the recent and modern advancements, and essentially work on the principle

47、 that there is a rise in seawater during high tide period and a fall during the low ebb period. The water rises and falls twice a day; each fall cycle occupying about 12 hours and 25 minutes. The advantage of this rise a

48、nd fall of water is taken in a tidal plant. In other words, the tidal range, i.e. the difference between high and low tide levels is utilized to generate pow</p><p>　　Water passes from the ocean to the basin

49、 during high tides, and thus running the turbines and generating electric power. During low tide，the water from the basin runs back to ocean, which can also be utilized to generate electric power, provided special turbin

50、es which can generate power for either direction of flow are installed. Such plants are useful at places where tidal range is high. Rance power station in France is an example of this type of power station. The tidal ran

51、ge at this place is </p><p>　　4.Hydro-plants or hydroelectric schemes may be classified on the basis of operating head on turbines as follows: ① low head scheme (head<15m),②medium head scheme (head varies

52、 between 15m to 60 m) ,③high head scheme (head>60m). They are described below:</p><p>　　(1) Low head scheme.</p><p>　　A low head scheme is one which uses water head of less than 15 meters or

53、so. A run off river plant is essentially a low head scheme, a weir or a barrage is constructed to raise the water level, and the power house is constructed either in continuation with the barrage or at some distance down

54、stream of the barrage, where water is taken to the power house through an intake canal.</p><p>　　(2) Medium head scheme</p><p>　　A medium head scheme is one which used water head varying between

55、 15 to 60 meters or so. This scheme is thus essentially a dam reservoir scheme, although the dam height is mediocre. This scheme is having features somewhere between low had scheme and high head scheme.</p><p&

56、gt;　　(3) High head scheme.</p><p>　　A high head scheme is one which uses water head of more than 60m or so. A dam of sufficient height is, therefore, required to be constructed, so as to store water on the u

57、pstream side and to utilize this water throughout the year. High head schemes up to heights of 1,800 meters have been developed. The common examples of such a scheme are: Bhakra dam in (Punjab), Rihand dam in (U.P.), and

58、 Hoover dam in (U.S.A), etc.</p><p>　　The naturally available high falls can also be developed for generating electric power. The common examples of such power developments are: Jog Falls in India, and Niaga

59、ra Falls in U.S.A.</p><p><b>　　水輪機(jī)和水力發(fā)電</b></p><p><b>　　摘要</b></p><p>　　水的能量可以通過(guò)三種基本方法來(lái)獲得：利用水的重力作用、水的壓力作用或水的流速作用，或者其中任意兩種或全部三種作用的組合。在如今的實(shí)際應(yīng)用中，佩爾頓式水輪機(jī)或沖擊式水輪機(jī)是

60、唯一只利用其中一種方法來(lái)獲取水能的，即利用一束或者好幾束高速的水流的作用獲得能量的一種水輪機(jī)。這種類型的水輪機(jī)通常應(yīng)用在高水頭電站上。法拉第曾經(jīng)指出：線圈在磁場(chǎng)中旋轉(zhuǎn)，就產(chǎn)生了電。因此，為了獲得電能，我們必須產(chǎn)生使“線圈”旋轉(zhuǎn)的機(jī)械能。用燃料或流水的能量帶動(dòng)原動(dòng)機(jī)（稱為渦輪機(jī)）就產(chǎn)生了機(jī)械能。這種機(jī)械能轉(zhuǎn)換成電能是通過(guò)電動(dòng)機(jī)來(lái)實(shí)現(xiàn)的，電動(dòng)機(jī)直接連接在渦輪機(jī)軸上，由渦輪機(jī)驅(qū)動(dòng)。因此，就在發(fā)電機(jī)的出線端獲得電能，然后輸送到需要它做功的地區(qū)。

61、發(fā)電需要的裝置或機(jī)械（即原動(dòng)機(jī)+發(fā)電機(jī)）統(tǒng)稱為動(dòng)力設(shè)備。安置所有機(jī)械和其他輔助設(shè)施的建筑稱為發(fā)電廠。</p><p>　　關(guān)鍵詞水輪機(jī)水力發(fā)電水電站種類水頭系統(tǒng)</p><p>　　從1925年開始，水輪機(jī)的最高效率達(dá)到93%或稍微高一點(diǎn)就沒(méi)有再提高了。就最大效率而言，水輪機(jī)的對(duì)水能的利用率已經(jīng)達(dá)到了實(shí)際發(fā)展的極限了。然而，在最近幾年里，水輪機(jī)的大小和單機(jī)容量卻增長(zhǎng)的很快。</p&g

62、t;<p>　　另外，人們還對(duì)引起空蝕的原因以及怎樣預(yù)防空蝕做了很多的研究，這些研究使得我們能夠在高于以前認(rèn)為的合適水頭下獲得更高的比轉(zhuǎn)速。更大的機(jī)組，更高的比轉(zhuǎn)速，以及水輪機(jī)的設(shè)計(jì)上的簡(jiǎn)化和改進(jìn)，這幾個(gè)方面的進(jìn)步使得水輪機(jī)一直以來(lái)在作為原動(dòng)力之一擁有很重要的地位。</p><p><b>　　1.水輪機(jī)的類型</b></p><p>　　水輪機(jī)可以分為

63、兩大類：沖擊式水輪機(jī)——利用高速水流沖擊水輪機(jī)的一小部分時(shí)產(chǎn)生的動(dòng)能；反擊式水輪機(jī)——利用充滿轉(zhuǎn)輪和過(guò)水道的水流所擁有的水的壓力和流速兩者相結(jié)合來(lái)獲得動(dòng)力。反擊式系列又分成兩種通用的型式：弗朗西斯式（有時(shí)稱作反擊式）以及旋槳式。旋槳式又進(jìn)一步再分為定輪葉式水輪機(jī)和以卡普蘭式代表的轉(zhuǎn)葉式水輪機(jī)。</p><p><b>　　1.1沖擊式水輪機(jī)</b></p><p>　

64、　在沖擊式水輪機(jī)上，壓力鋼管中的水從噴嘴孔口中射出，這時(shí)水的的勢(shì)能轉(zhuǎn)換成動(dòng)能。射流自由地射入水輪室內(nèi)的空氣中，撞擊在轉(zhuǎn)輪的碗狀戽斗上。戽斗每旋轉(zhuǎn)一周進(jìn)入射流、經(jīng)過(guò)并從射流轉(zhuǎn)出一次。在這段時(shí)間內(nèi)戽斗承受著射流的全部沖擊力。這種沖擊力產(chǎn)生一個(gè)高速錘擊沖打在戽斗上。與此同時(shí)，戽斗受到離心力的作用而有脫離它的座盤的趨勢(shì)，由此而產(chǎn)生的應(yīng)力以及水流在戽斗的碗狀工作面上的沖刷作用都很大，因而需要選用能抵御水力磨損和疲勞的高質(zhì)量材料，一般都采用青銅和韌

65、化鑄鋼，只有水頭很低時(shí)才能用鑄鐵。</p><p>　　1.2弗朗西斯式轉(zhuǎn)輪</p><p>　　就弗朗西斯式水輪機(jī)來(lái)說(shuō)，來(lái)自蝸殼或水槽內(nèi)的流速較低的水，通過(guò)位于轉(zhuǎn)輪周圍的導(dǎo)葉或一些閘門，然后流經(jīng)轉(zhuǎn)輪，并從轉(zhuǎn)輪泄入安置在尾水位以下而不與大氣相通的尾水管內(nèi)。由于水充滿所有的水道并作用在轉(zhuǎn)輪的整個(gè)周圍，因此，僅有一小部分動(dòng)力來(lái)自水的流速所引起的動(dòng)力作用，而大部分動(dòng)力則都通過(guò)作用在轉(zhuǎn)輪葉片前后工

66、作面上的壓力差取得。尾水管可以使能利用的水頭得到充分的利用，這一方面是由于轉(zhuǎn)輪下面垂直水柱所產(chǎn)生的吸出作用，另一方面是由于尾水管的出口面積大于緊接轉(zhuǎn)輪下喉管的面積，從而使水流離開轉(zhuǎn)輪葉片時(shí)的一部分動(dòng)能得以利用。</p><p><b>　　1.3旋槳式轉(zhuǎn)輪</b></p><p>　　旋槳式機(jī)組最適用于低水頭電站，在它適用的水頭范圍內(nèi)，已產(chǎn)生了顯著的經(jīng)濟(jì)效果。這種水輪

67、機(jī)的轉(zhuǎn)速比較高，以致使發(fā)電機(jī)的價(jià)格較低，并使發(fā)電廠房的水下結(jié)構(gòu)和水上結(jié)構(gòu)的尺寸都比較小。低水頭、小功率的旋槳式轉(zhuǎn)輪，有時(shí)用鑄鐵來(lái)制造。水頭高于20英寸時(shí)，都用一種更為可靠的材料──鑄鋼來(lái)制造。大直徑的螺旋槳可用單個(gè)葉片固定在輪轂上制成。</p><p><b>　　1.4轉(zhuǎn)葉式水輪機(jī)</b></p><p>　　轉(zhuǎn)葉旋槳式水輪機(jī)是從定輪葉旋槳式水輪機(jī)發(fā)展而成的。卡普蘭

68、式水輪機(jī)是這類水輪機(jī)中為人們最為熟悉的一種。它的葉片可由液壓伺服器調(diào)整到效率最大的角度。利用伺服器上的凸輪能使葉片的角度隨閥門的開啟位置而變化，從而在所有各種滿負(fù)載百分率情況下都能保持高效率。</p><p>　　由于轉(zhuǎn)葉旋槳式水輪機(jī)組在閘門各種開度情況下效率都高，因此，它特別適用于那些必須在變負(fù)載和變水頭條件下運(yùn)行的低水頭電站上。當(dāng)然，這種機(jī)組的投資費(fèi)用和維護(hù)費(fèi)用要高于只能在一個(gè)最大效率點(diǎn)上運(yùn)行的定輪葉旋槳式水

69、輪機(jī)組。</p><p><b>　　2火電和水電</b></p><p>　　如上所述，渦輪機(jī)葉片是由燃料或流水的能量帶動(dòng)的。用燃料產(chǎn)生蒸汽驅(qū)動(dòng)蒸汽渦輪機(jī)時(shí)，所產(chǎn)生的電稱為火電。由于產(chǎn)生蒸汽的燃料是一般燃料如煤、燃料油等，或是原子能燃料即核燃料。直接燃燒煤產(chǎn)生水蒸氣，煤是最簡(jiǎn)便、最古老的一種燃料。柴油等也可以作為產(chǎn)生蒸汽的燃料。原子燃料如鈾、釷也可用于產(chǎn)生蒸汽。用傳

70、統(tǒng)燃料如煤、燃料油等（稱為礦物燃料）產(chǎn)生蒸汽來(lái)帶動(dòng)水輪機(jī)時(shí)，這種發(fā)電廠一般稱為普通火力發(fā)電廠或熱電廠。但當(dāng)原子燃料用于產(chǎn)生蒸汽時(shí)，這種發(fā)電廠（基本上屬于火力發(fā)電廠）稱為原子能發(fā)電廠或核電廠。一般火力發(fā)電廠是用鍋爐產(chǎn)生蒸汽的，而原子能發(fā)電站是用核反應(yīng)堆和蒸汽發(fā)生器代替鍋爐產(chǎn)生蒸汽的。這兩種情況產(chǎn)生的電能稱為火電。該系統(tǒng)稱為火力發(fā)電系統(tǒng)。</p><p>　　然而，用流水的能量驅(qū)動(dòng)水輪機(jī)時(shí)，所產(chǎn)生的電稱為水電。這種系

71、統(tǒng)稱為水力發(fā)電系統(tǒng)，而發(fā)電廠稱為水力發(fā)電廠或水電站。在水電系統(tǒng)中必須使具有一定勢(shì)能和一定數(shù)量的水流流經(jīng)水輪機(jī)。勢(shì)能使水流動(dòng)，驅(qū)動(dòng)水輪機(jī)的葉片，這樣與水輪機(jī)連接的發(fā)電機(jī)就發(fā)出電能。本章只涉及水力發(fā)電系統(tǒng)的內(nèi)容。</p><p><b>　　3水力發(fā)電站的種類</b></p><p>　　根據(jù)水力特性把水力發(fā)電站分為下列幾種：①?gòu)搅魇诫娬?，②蓄水式電站，③抽水蓄能電站，?/p>

72、潮汐電站。各類電站分述如下：</p><p><b>　　(1)徑流式電站</b></p><p>　　這類電站是在河流上游無(wú)適宜的水庫(kù)的情況下利用河流最小流量的電站。有時(shí)修建攔河堰壩，把水位提高并保持在預(yù)定的數(shù)值，只允許在很小的范圍內(nèi)變化。它可以單獨(dú)為電站服務(wù)，或者主要為其他目標(biāo)服務(wù)，兼顧電站。這種方案基本上是一種低水頭方案，它僅適用于枯水季流量值得開發(fā)的常年性河流

73、。</p><p>　　徑流式電站通常具有很小的蓄水庫(kù)容，有徑流時(shí)方能利用。這個(gè)很小的蓄水庫(kù)容是為滿足每小時(shí)負(fù)荷的變化而設(shè)立的。當(dāng)河道的來(lái)水流量大于發(fā)電需要時(shí)（在非峰荷期間），多余的水量就暫時(shí)蓄存在攔河建筑物上游的小水庫(kù)中，以供峰荷期間使用。</p><p>　　徑流式電站有諸多例子：楠加爾?海德?tīng)栠\(yùn)河的岡古瓦爾和科拉水電站，恒河的默罕默德?普爾和帕特里水電站以及薩爾達(dá)運(yùn)河的薩爾達(dá)水電站。

74、</p><p>　　在灌溉渠道的跌水處修建的電站也屬于徑流式水電站。</p><p><b>　　(2)蓄水式電站</b></p><p>　　蓄水式電站基本都有一足夠大的上游蓄水庫(kù)，貯存季風(fēng)季節(jié)到干旱夏季的徑流量，從而提供一個(gè)比枯季最小流量大得多的穩(wěn)定流量。在這種設(shè)計(jì)方案中，水壩攔河修筑，電站可以布置在腳下，如巴克拉、希陶庫(kù)德，里亨得工程等

75、。電站也可能位于大壩下游很遠(yuǎn)的地方。在這種情況下，電站位于水庫(kù)輸水隧道的末端。輸水隧道借助于壓力水管與電站的機(jī)械裝置連接，壓力水管可能在地下（如邁吞和高勒工程），也可能在地上（如孔達(dá)工程）。</p><p>　　當(dāng)電站位于大壩附近時(shí)，它一般采用低水頭發(fā)電裝置，這種電站稱為集中落差式水力發(fā)電工程；但是當(dāng)水流從大壩經(jīng)過(guò)渠道、隧道或壓力水管長(zhǎng)距離輸送到電站時(shí)，則稱為分散落差式水力發(fā)電工程。</p><

76、;p><b>　　(3)抽水蓄能電站</b></p><p>　　抽水蓄能電站在峰荷期間發(fā)電，但在非峰荷期間，又把水從尾水池抽回到蓄水前池供以后使用。抽水機(jī)是由該系統(tǒng)其它電站的輔助電力驅(qū)動(dòng)的。因而，這類抽水蓄能電站主要用于協(xié)調(diào)現(xiàn)有的火電站或別的水電站。</p><p>　　在峰荷期間，水從水庫(kù)流入水輪機(jī)而產(chǎn)生電能。在非峰荷期間，利用其他電站的剩余電能，從尾水池抽

77、水到前池，因而這個(gè)較小的電站為另一個(gè)較大的電站補(bǔ)充電能。在這樣的系統(tǒng)中，同樣的水量被一次又一次的重復(fù)利用，而沒(méi)有被浪費(fèi)。</p><p>　　為了利用在15～90米之間變化的水頭，已制造出一種可逆式的水泵──水輪機(jī)，它既可以作為水輪機(jī)也可作為水泵。這種可逆式水輪機(jī)可高效率地運(yùn)轉(zhuǎn)，有助于減少這類電站的投資。同樣，同一種電力設(shè)備既可做發(fā)電機(jī)，又可通過(guò)電極的互換而用作馬達(dá)。這個(gè)系統(tǒng)中的設(shè)備非常有助于提高電力系統(tǒng)的負(fù)載系

78、數(shù)。</p><p><b>　　(4)潮汐電站</b></p><p>　　用潮汐電站發(fā)電是近現(xiàn)代的成就。它是根據(jù)海水在高潮期上升、在落潮期下降的原理工作的。海水一日漲落兩次。每次漲潮周期大約是12小時(shí)25分。潮汐電站就是利用水位漲落的效益，換言之，就是利用高低潮之間的水位差進(jìn)行發(fā)電的。為此，要修建一個(gè)水池，用隔墻和大海隔開，關(guān)在隔墻的孔洞里安裝水輪機(jī)，就可以發(fā)電。

79、</p><p>　　在高潮期間海水流入水池，驅(qū)動(dòng)水輪機(jī)發(fā)電。在落潮期間，水又從水池流回海洋。只要安裝一種在兩個(gè)水流方向都能發(fā)電的特種水輪機(jī)組，就能利用流回海洋的水流進(jìn)行發(fā)電。這類電站在潮差大的地方是很有用的。法國(guó)的朗斯電站就是這類電站的一個(gè)例子。那里的達(dá)到11米。該站擁有九臺(tái)機(jī)組，裝機(jī)容量為38000千瓦。</p><p>　　4根據(jù)水輪機(jī)的工作水頭，可把水電站（或水電系統(tǒng)）分為下列幾種

80、：①低水頭系統(tǒng)（落差小于15米）；②中水頭系統(tǒng)（落差變化在15～60米）；③高水頭系統(tǒng)（落差大于60米）?，F(xiàn)分述如下：</p><p><b>　　(1)低水頭系統(tǒng)</b></p><p>　　低水頭系統(tǒng)使用的水頭小于15米左右。徑流式電站基本上屬于低水頭電站。在該系統(tǒng)中，修建攔河壩提高水位，電站或建在攔河壩的一端或建在壩的下游，離攔河壩有一定距離的地方，通過(guò)引水渠把

81、水送往電站。</p><p><b>　　(2)中水頭系統(tǒng)</b></p><p>　　中水頭系統(tǒng)使用的水頭變化在15米到60米左右。因此該系統(tǒng)基本上是一種大壩水庫(kù)系統(tǒng)，盡管大壩的高度不很大。在低水頭和高水頭系統(tǒng)之間，該系統(tǒng)在某些地方是有其優(yōu)點(diǎn)的。</p><p><b>　　(3)高水頭系統(tǒng)</b></p>