Chapter 8 Electric Power Generation section 8-2 Hydropower Plants 电气工程及其自动化专业英语课件

New Words and Expressions
nozzle n. 喷嘴 periphery n. 周边，周围，外围，范围 blade n. 叶片，轮叶 spoked wheel 辐轮 start up 起动，开动，触发 thermal plant 热电厂 dispatcher 调度员 sparingly 节省地，有节制地，少量地
摘要多采用过去时态叙述作者工作，以现在时态 叙述作者结论。一般使用第三人称，而不使用第一、 第二人称。
Abstracts
摘要中常用到的词汇归纳如下： be described （ 描 述 ） ， be introduced （ 介 绍 ） ， be expounded （详细 解释 ） ，be proposed （提出） ，be discussed（讨论），be analyzed（分析），be offered （提供），be pointed out（指出），be inferred（推 导），be developed（开发），be tested（验证），be testified（验证），be diagnosed（诊断），be used（使 用 ） ， be built （ 建 立 ） ， be adopted （ 采 用 ） ， be applied（应用），be investigated（调查），be proved （证明），be compared（比较），be concluded（得出 结论），be considered（考虑），be improved（改进）， be presented（提出），be studied（研究），
Return
New Words and Expressions
hydropower n. 水力，水力发电 cubic a. 立体的，三次的，体积的，正六面体的 dam n. 坝，堰 penstock n. 水道，压力水管 hydroplant n. 水电厂，水电站 high head 高水头 low head 低水头 tail race 尾水渠，退水渠
New Words and Expressions
spillway n. 泄水道，溢水孔 base-loading 基荷 pumped storage 抽水蓄能 peakห้องสมุดไป่ตู้load 高峰负荷 off-peak 非峰值的 on-line 在线 daily load-demand curve 日负荷曲线
Abstracts
（4）结论是对结果的分析、研究、比较、评价和应用， 提出的问题，今后的课题，假设，启发，建议预测等。
在有些情况下，摘要中也可包括研究工作的主要 对象和范围，以及具有情报价值的其它重要的信息。 但不应有引言中出现的内容，也不要对论文内容作诠 释和评论，不得简单重复题名中已有的信息。摘要的 句型力求简单，语句顺畅，使作者或审稿人能够一目 了然，把握住论文的主题和必要信息。篇幅不宜过长， 一般不超过200个单词。
Section 2 Hydropower Plants
demand the pumped storage scheme provides power that would otherwise have to be supplied by less efficient (older) plants. In a sense, from the point of view of the thermal part of the system, the pumped storage scheme "shaves the peaks" and "fills the troughs" of the daily load-demand curve.
Section 2 Hydropower Plants
Fig.8-4 Cross section through a hydroelectric plant with a Kaplan turbine
Section 2 Hydropower Plants
We note a highly desirable feature of hydropower plants: the speed with which they may be started up, brought up to speed, connected to the power network, and "loaded" up. This can be done in under 5 minutes, in contrast to many hours in the case of thermal plants; the job is also much simpler and adaptable to remote control. The hydropower is well suited for turning on and off at a dispatcher's command to meet changing power needs. We note that when water is in short supply, it is desirable to use the limited available potential energy sparingly,
Section 2 Hydropower Plants
Fig.8-4 shows a cross section through a hydroelectric plant with a Kaplan turbine. Some of the generator features should be noted. The rotation axis is vertical. With a speed of 144 rpm we should have 50 poles to generate 60 Hz. These poles are mounted on the periphery of a spoked wheel called a spider. There is space between the poles to accommodate the pole windings. The rotor called by the descriptive title salient pole.
The desirable feature of hydropower in effectively meeting peak demand may be obtained in locations without suitable water flows by using pumped storage. In this scheme water is pumped from a lower reservoir to a higher one during offpeak times (generally at night) and the water is allowed to flow downhill in the conventional hydroelectric mode during times of peak demand.
New Words and Expressions
shaves the peaks fills the troughs bucket wheel rotor
（负荷曲线的）削峰 （负荷曲线的）填谷 勺轮转子
Return
Abstracts
摘要
摘要是以提供论文梗概为目的，不加评论和补充 解释，以精练的语言简单扼要、重点突出、确切地讲 明本文所介绍或阐述的重要内容的短文。摘要中通常 包括4个要素，既研究目的、研究方法、研究结果和结 论。 （1）研究目的是指研究、研制、调查等的前提、目的 任务，以及所涉及的主题范围； （2）研究方法是指所采用的新原理、理论、条件、材 料、工艺、结构、手段、装备和程序等； （3）研究结果是指实验或研究的结果、数据、得到的 关系、观察的现象、性能等；
Section 2 Hydropower Plants
for periods of short duration, to meet the peak-load demands. When water is plentiful with the excess flowing over the spillway of the dam, base-loading use is indicated.
Section 2 Hydropower Plants
Off peak, the generators, operating as synchronous motors, drive the turbines in reverse in a pumping mode. The overall efficiency is only about 65% to 70%, but the economics are frequently favorable when one considers the economics of the overall system, including the thermal units. Consider the followings. It is not practical to shut down the largest and most efficient thermal units at night, so they are kept "on-line" supplying relatively small (light) loads. When operating in this mode the pumping power may be supplied at low incremental costs . On the other hand , at the time of peak