浙江大学2010年-2014年博士生入学考试电力系统分析试题真题
《 电力系统分析》试卷及答案
XXXX大学期末考试《电力系统分析》试卷(B答案一、填空题（20分，每空1分）1.衡量电能质量的基本指标是电压和频率。
2.一台发电机接入 10kV 母线，经一台升压变压器接入220kV网络，发电机额定电压为 10.5 kV，变压器一、二次侧额定电压分别为 10.5 kV、_242____kV。
3.派克变换相当于把观察者的立场从静止的定子上转到了转子，定子的三相绕组被两个同转子一起旋转的等效dd 绕组和qq 绕组代替。
派克变换可以使磁链方程的系数变为常数，简化求解。
a、b、c系统中的直流分量和基频交流分量经派克变换分别对应d、q、0系统中的基频和直流分量。
4.同步发电机纵轴暂态电抗为 xd’，其物理意义是沿纵轴向把同步电机看做是双绕组变压器，当副方绕组（即励磁绕组）短路时，从原方（即定子绕组）测得的电抗。
5.短路是指一切不正常的相与相之间或相与地（对于中性点接地的系统）发生通路的情况。
在三相系统中，可能发生的短路有：_三相短路_、单相短路、_两相短路___和_两相接地短路几种类型。
二、简答题（35分，每题7分）1.分裂导线和导线换位对线路的参数分别有什么影响？架空线路的等值电路有哪两种？当线路距离很长（大于500km）时，应如何表示架空线路的等值电路？（7分）分裂导线相当于_增大___了导线的等效半径，因而能减小导线的电感。
（增大/减小）。
架空线路的导线排列不对称时，可以通过__导线换位__使三相参数恢复对称。
当线路距离很长（大于500km）时，可用多个等值电路代替。
2.节点阻抗矩阵元素（对角元和非对角元）的物理意义分别是什么？（7分）节点k的自阻抗的物理意义为：当在节点k单独注入电流，而所有其他节点注入电流都等于z。
零时，在节点k的电压同注入电流之比，即等于kk3.同步发电机突然三相短路后，定子绕组和转子绕组中各有哪些短路电流分量？其对应关系如何？（7分）答：同步发电机突然短路后，定子电流中包括基频分量、直流分量和倍频分量，直流分量和倍频分量都是为了维持磁链初值守恒而出现的，是自由分量，基频电流的稳态值是强制分量，基频电流与稳态电流之差也是自由电流。
电路历年真题试卷汇编2
电路历年真题试卷汇编2(总分：76.00，做题时间：90分钟)一、解答题(总题数：38，分数：76.00)1.(清华大学2007年考研试题)电路如图12—6所示，已知对称三相电源的内阻抗Z 1 =1+j1Ω，Y形连接对称三相负载阻抗Z 2 =30+j40Ω。
求b、C问短路时的短路电流I bc。
（分数：2.00）__________________________________________________________________________________________正确答案：(正确答案：根据KCL，可知：在已知电路中，对b相和c相列KVL方程：整理，可得：因此：)解析：2.(清华大学2005年考研试题)已知如图12—7所示电路中对称三相电源线电压，阻抗Z 1=50+j50Ω，Z 2 =20Ω，Z 3 =40+j80Ω，中线电阻R=3Ω。
(1)求图示功率表的读数；(2)求A相电源UA发出的有功功率和无功功率。
（分数：2.00）__________________________________________________________________________________________正确答案：(正确答案：(1)题图所示电路中，阻抗Z 1直接并接在A相电源上，对功率表的读数没有影响。
求功率表读数电路如图12—8(a)所示，其单相计算电路如图12—8(b)所示。
则可得：(2)A相电源发出的有功功率：A相电流：因此，A相电源发出的有功功率：P A发=220×5．294cos(-30°+78．35°)=774W A相电源发出的无功功率：Q A发=220×5．294sin(一)解析：3.(华中科技大学2007年考研试题)在如图12—9所示对称正序正弦稳态三相电路中，已知电源A相的相电压为，R 1 =20Ω，Z 1 =i10Ω，Z 2 =一j20Ω，f=50Hz。
电力系统分析习题和答案解析
电力系统分析目录第一部分电力系统稳态分析第一章电力系统的基本概念第二章电力系统的元件参数及等值电路第三章简单电力系统的计算和分析第四章电力系统潮流的计算机算法第五章电力系统的有功功率和频率调整第六章电力系统的无功功率和电压调整第二部分电力系统暂态分析第七章电力系统故障分析的基本知识第八章同步发电机突然三相短路分析第九章电力系统三相短路的实用计算第十章对称分量法及元件的各序参数和等值电路第十一章不对称故障的分析、计算第十二章电力系统各元件的机电特性第十三章电力系统静态稳定第十四章电力系统暂态稳定第十五章研究生入学考试试题附录第一部分电力系统稳态分析电力系统稳态分析，研究的内容分为两类，一类是电力系统稳态运行状况下的分析与潮流分布计算，另一类是电力系统稳态运行状况的优化和调整。
第一章电力系统的基本概念1-1 什么叫电力系统、电力网及动力系统？电力系统为什么要采用高压输电？1-2 为什么要规定额定电压？电力线、发电机、变压器和用电设备的额定电压是如何确定的？1-3 我国电网的电压等级有哪些？1-4 标出图1-4电力系统中各元件的额定电压。
1-5 请回答如图1－5所示电力系统中的二个问题：⑴ 发电机G 、变压器1T 2T 3T 4T 、三相电动机D 、单相电灯L 等各元件的额定电压。
⑵ 当变压器1T 在+2.5%抽头处工作，2T 在主抽头处工作，3T 在-2.5%抽头处工作时，求这些变压器的实际变比。
1-6 图1-6中已标明各级电网的电压等级。
试标出图中发电机和电动机的额定电压及变压器的额定变比。
1-7 电力系统结线如图1-7所示，电网各级电压示于图中。
试求：⑴发电机G 和变压器1T 、2T 、3T 高低压侧的额定电压。
⑵设变压器1T 工作于+2.5%抽头， 2T 工作于主抽头，3T 工作于-5%抽头，求这些变压器习题1-4图的实际变比。
1-8 比较两种接地方式的优缺点，分析其适用范围。
1-9 什么叫三相系统中性点位移？它在什么情况下发生？中性点不接地系统发生单相接地时，非故障相电压为什么增加3倍？1-10 若在变压器中性点经消弧线圈接地，消弧线圈的作用是什么？1-11 什么叫分裂导线、扩径导线？为什么要用这种导线？1-12 架空线为什么要换位？规程规定，架空线长于多少公里就应进行换位？1-13 架空线的电压在35kV以上应该用悬式绝缘子，如采用X—4.5型绝缘子时，各种电压等级应使用多少片绝缘子？第二章电力系统各元件的参数及等值网络2-1 一条110kV、80km的单回输电线路，导线型号为LGJ—150，水平排列，其线间距离为4m，求此输电线路在40℃时的参数，并画出等值电路。
(完整word版)浙江大学电气学院考博电力系统分析历年真题-2016(回忆版)
电力系统分析考题20081。
电力系统潮流计算与电力系统状态估计的异同？2.什么是派克变换，为什么要进行派克变换，其物理意义是什么？为什么在计算暂态稳定时又要统一变换到xy坐标系统?3。
试述电力系统无功功率的本质？画出电力系统无功-电压曲线，并作简要分析？4.写出单机无穷大系统的经典二阶模型方程,并用小扰动分析法分析其在平衡点的稳定性？5.画出电力系统暂态稳定计算的流程框图,并作简要分析？电力系统分析考题2010我只知道三道大题是考的什么,具体的数值肯定不知道了电力分为选择、填空、三个大题选择、填空好像就有60分了，三道大题40分选择、填空（据师兄说很简单）都是课本上的第一道大题:求解电网节点的导纳矩阵二:不对称故障的分析计算，三相短路电流的计算以及其他类型的不对称短路计算三：电力系统稳定分析(论述题)，不用计算电力系统分析考题20111、填空题，比较简单，书上一些概念2、（1）什么是电力系统中性点,有那种？有什么区别和作用(2）提高静态稳定和暂态稳定的措施有哪些？优缺点是什么?3、求矩阵导纳，其中包括变压器的 变换4、求电力系统的标幺值，电力系统分析考题2013填空、判断、单选计算：1、导纳矩阵的修改：两节点间增加一条支路、从一个节点新增一条变压器支路2、小干扰稳定性分析（包含励磁模型,何仰赞华中科技大学电力系统分析的书上有）电力系统分析考题2014一、单项选择题总共50分，10道题。
考察的比较多,也比较杂。
如问暂态稳定计算是用的什么微分方程（选项有常微分方程、偏微分方程等)；问500KV输电线路的自然阻抗大约多少,有选项可选的;问谐波滤波是属于电磁暂态、机电暂态还是什么过程;问高压输电能减小输电损耗的原理；其他的记不清了.。
二、计算题发电机的电磁功率特性计算。
利用有关功率平衡,有关公式计算发电机电磁功率型的计算题。
这题要在熟知《电力系统分析》（何仰赞，温增银，下册）中的第16章例题16—1，例题16—2的基础上,才能会计算。
电力系统分析试卷及答案完整版
电力系统分析试卷及答案HUA system office room 【HUA16H-TTMS2A-HUAS8Q8-HUAH1688】电力系统分析练习题一、简答题1、电力线路的正序电抗与零序电抗是否相等？2、在220kV及以上的超高压架空线路上，普遍采用分裂导线，采用分裂导线后，线路电感、线路并联电容会增大还是变小？3、动力系统、电力系统和电力网的基本构成形式如何？4、电力变压器的主要作用是什么？5、采用标么值计算有什么优点？6、对电力系统运行的要求是什么？7、试画出单相变压器等值电路。
8、试画出电力线路等值电路。
二、如图所示的电力系统1.确定发电机G，变压器T-1、T-2、T-3，线路L-1、L-2、L-3及电容器Y c的额定电压；2.给出其稳态分析时的等值电路；3.输电线路L-3阻抗为5+j20Ω（忽略并联支路），末端有功功率为10MW，功率因数为0.80（感性），末端电压为35kV，计算线路L-3的功率损耗和电压损耗；4.条件同3，但功率因数提高到0.90（感性），请问线路L-3的功率损耗和电压损耗会增加还是减少三、电力系统接线如下图所示，电网各级电压示于图中，求1)发电机和各变压器高低压侧额定电压；2)设T-1 高压侧工作于+2.5%抽头，T-2工作于主抽头，T-3高压侧工作于-5%抽头，求各变压器实际变比。
四93kW,短路电压耗、G、B。
五、一容量比为90/90/60兆伏安，额定电压为220/38.5/11千伏的三绕组变压器。
工厂给出试验数据为：ΔP s’(1-2)=560千瓦，ΔP s’(2-3)=178千瓦，ΔP s’(3-1)=363千瓦，V S（1-2）%=13.15, VS（2-3）%=5.7, VS（3-1）%=20.4,ΔP=187千瓦，I0 %=0.856。
试求归算到220千伏侧的变压器参数。
（注：功率值未归算，电压值已归算）六、已知某一变压器参数如表1所示。
表1变压器绕组电阻、漏抗、励磁支路电导和励磁支路电纳的计算公式分别为：1、试计算变压器绕组电阻、漏抗的有名值；2、设S B=100MVA ，110kV 级为基本级，U B=121kV ，试计算变压器绕组电阻、漏抗的标幺值。
浙大电气复试(笔试+面试)
郑重声明：WORD内容均为本人在准备浙大保研复试时所搜集，仅供参考，祝各位同学都能进自己理想的大学。
同时：最后面有我本人此次复试的内容（笔试+面试）我前年复试的题，具体现在忘记了，大致如下：上午复试的内容分四部分（一份卷子）：第一部分发电厂电气部分，题型为问答题，大致有：一题电力系统主接线图，系统各种主接线的优缺点（给出主接线图，让说出是哪种接线，其优缺点，检修某条线路应该操作哪些开关以及开关顺序等）；一题是限流电抗器的选择（即选择电抗器需要考虑哪些因素）；第二部分三个题：一道是导纳矩阵的改写，即增删元件后改写矩阵；一道是电力系统中的负荷模型；第三题是牛拉法潮流计算（我的上一届考的是直流法潮流计算，一般不超过三个节点）第三部分两道题：一道是根轨迹；一道是二阶系统响应曲线（给出曲线，根据曲线写出二阶系统的传递函数）第四部分是一道短文翻译题，英译汉（为电力系统相关的文章，本次是一篇关于中国电网发展的报道性文章）面试：问我的题目只是很多题目中很少一部分每个人不一样的，仅供参考一题：一台半接线交叉接线的优点一题：电力系统中有哪些有功和无功电源一题：电力系统电流三段式保护包含哪三段一题：线路投入时，是先投入断路器还是先投入保护一题：高压输电线路和城市配网的保护哪个更复杂？为什么？一题：电力系统中性点接地方式有哪些？各对应哪些电压等级？一题：中性点不接地系统中，发生单相接地短路时有没有短路电流流过，为什么？（2）2010年的考研复试题目，你可以参考一下（友情感谢辉哥，xp，顺祝福辉哥和某师妹开心快乐）：发电厂电气部分：主接线的桥形接线的特征、优点和倒闸操作15分母线为什么按锅炉分段5分电力系统分析：导纳矩阵及修改10分根据短路和开路实验求变压器四参数10分电力系统的正序、负序、零序网络，并求短路电流分量20分自动控制：看图根据上升时间，峰值时间，%,超调量写传递函数15分根据传递函数画根轨迹、稳定判据15分翻译：关于最优潮流控制的专业翻译10分笔试部分：话说当年复试试卷（笔试部分）里有五门课程，2小时时间；专业英语10分：考的是最优潮流的翻译，大概十七八行，我翻译快半小时了，挺长，各位复试的同学自己把握下度；诸如optimal power flow （OPF）最有潮流等等专业词汇要掌握；发电厂电气部分15分：主接线10分，考的是桥形接线；厂用电5分，考的第五章厂用电。
电力系统分析试题答案（完整试题）
电⼒系统分析试题答案（完整试题）⾃测题（⼀）—电⼒系统的基本知识⼀、单项选择题（下⾯每个⼩题的四个选项中，只有⼀个是正确的，请你在答题区填⼊正确答案的序号，每⼩题2.5分，共50分）1、对电⼒系统的基本要求是（）。
A、保证对⽤户的供电可靠性和电能质量，提⾼电⼒系统运⾏的经济性，减少对环境的不良影响；B、保证对⽤户的供电可靠性和电能质量；C、保证对⽤户的供电可靠性，提⾼系统运⾏的经济性；D、保证对⽤户的供电可靠性。
2、停电有可能导致⼈员伤亡或主要⽣产设备损坏的⽤户的⽤电设备属于（）。
A、⼀级负荷；B、⼆级负荷；C、三级负荷；D、特级负荷。
3、对于供电可靠性，下述说法中正确的是（）。
A、所有负荷都应当做到在任何情况下不中断供电；B、⼀级和⼆级负荷应当在任何情况下不中断供电；C、除⼀级负荷不允许中断供电外，其它负荷随时可以中断供电；D、⼀级负荷在任何情况下都不允许中断供电、⼆级负荷应尽可能不停电、三级负荷可以根据系统运⾏情况随时停电。
4、衡量电能质量的技术指标是（）。
A、电压偏移、频率偏移、⽹损率；B、电压偏移、频率偏移、电压畸变率；C、⼚⽤电率、燃料消耗率、⽹损率；D、⼚⽤电率、⽹损率、电压畸变率5、⽤于电能远距离输送的线路称为（）。
A、配电线路；B、直配线路；C、输电线路；D、输配电线路。
6、关于变压器，下述说法中错误的是（）A、对电压进⾏变化，升⾼电压满⾜⼤容量远距离输电的需要，降低电压满⾜⽤电的需求；B、变压器不仅可以对电压⼤⼩进⾏变换，也可以对功率⼤⼩进⾏变换；C、当变压器原边绕组与发电机直接相连时（发电⼚升压变压器的低压绕组），变压器原边绕组的额定电压应与发电机额定电压相同；D、变压器的副边绕组额定电压⼀般应为⽤电设备额定电压的1.1倍。
7、衡量电⼒系统运⾏经济性的主要指标是（）。
A、燃料消耗率、⼚⽤电率、⽹损率；B、燃料消耗率、建设投资、⽹损率；C、⽹损率、建设投资、电压畸变率；D、⽹损率、占地⾯积、建设投资。
浙江大学博士研究生入学考试英语真题2014年.doc
浙江大学博士研究生入学考试英语真题2014年(总分：130.00，做题时间：180分钟)一、单选题(总题数：10，分数：10.00)1.The two friends sat in a corner and _____ away to each other about the weather．（分数：1.00）A.talkedB.chattedC.mutteredD.whispered2.He is going to _____ the meeting on the subject of war and peace in a minute．（分数：1.00）A.speakB.talkC.remarkD.address3.Although not an economist himself, Dr. Smith has long been a severe critic of the government's _____ policies. （分数：1.00）A.economicB.economicalC.economyD.economics4.There are not many teachers who are strong _____ of traditional methods in English teaching. （分数：1.00）A.sponsorsB.contributorsC.advocatesD.performers5.A friendship may be _____ , casual, situational or deep and lasting. （分数：1.00）A.identicalB.superficialC.criticalD.original6.Nobody yet knows how long and how seriously the shakiness in the financial system will _____ down the economy. （分数：1.00）A.putB.settleC.dragD.knock7.We are _____ to the idea, but we doubt whether the time is ripe to put it into force. （分数：1.00）A.equalB.adequateC.considerateD.sympathetic8.People were surprised to find that Mr. Johnson had the ability to _____ everything he was involved in. （分数：1.00）A.PrevailB.dominateC.preside9.You can do it if you want to, but in my opinion it’s not worth the _____ it involves. （分数：1.00）A.forceB.trialC.attemptD.effort10.The manager gave one of the salesgirls an accusing look for _____ her attitude toward customers. （分数：1.00）A.straightforwardB.partialC.favorableD.hostile二、完形填空(总题数：1，分数：20.00)Throughout history man has had to accept the fact that all living things must die. But people now live longer than they(1). Yet, all living things still show the(2)of aging, which will eventually(3)death. Aging is not a disease, （but）as a person passes maturity, the cells of the body and the(4) they form do not function as well as they(5) in childhood and teenage years. The body provides less(6)against disease and is more(7)to have accident. A number of related causes may(8)aging. Some cells of the body have a （fairly） long life, but they are not(9)when they die. As a person ages,(10)of brain cells and muscle cells decreases.(11)body cells die and are （replaced） by new cells. In an aging person the(12)cells may not be as workable or as capable(13)growth as those of a young person. Another(14)in aging may be changes within the cells(15). Some of the protein chemicals in cells are known(16)with age and become less elastic. This is why the skin of old people wrinkles and(17). This is also the reason why old people(18)in height. There may be other more important chemical changes in the cells. Some complex cell chemicals, such as DNA and RNA, store and(19)information that the cells need.Aging may affect this(20)and change the information carrying molecules so that they do not transmit the information as well.（分数：20.00）A.wouldB.be used toed toedA.functionB.effectC.affectD.signA.lead inB.give inC.run intoD.result inA.handsB.feetC.heartansA.doB.has doneC.didD.had doneB.protectionC.vigorD.powerA.likelyB.probableC.possibleD.alikeA.attend toB.contribute toC.add toD.devote toA.replacedB.rebornC.recoveredD.surrenderedA.a numberB.the amountC.the numberD.mostA.oldB.leftC.newD.otherA.toB.forC.ofD.inA.factorB.effectC.reasonD.elementA.for themselvesB.of themselvesC.themselvesD.on their ownA.changeB.to have changedC.to changeD.to being changedA.increaseB.shrinkC.lengthenD.decreaseA.pass awayB.pass byC.pass offD.pass onA.improvementB.processionC.approachD.process三、阅读理解(总题数：4，分数：80.00)In the same way that a child must be able to move his arms and legs before he can learn to walk, the child must physiologically be capable of producing and experiencing particular emotions before these emotions can be modified through learning. psychologists have found that there are two basic processes by which learning takes place. one kind of learning is called "classical conditioning". this occurs when one event or stimulus is consistently paired with, or followed by, a reward or punishment, it is through classical conditioning that a child learns to associate his mother's face and voice with happiness and love, for he learns that this person provides food and comfort. negative emotions are learned in a similar fashion. The second kind of learning is called "operant conditioning." this occurs when an individual learns to do things that produce rewards in his environment and learns not to do things that produce punishments. for example, if a mother always attends to her baby when he cries and cuddles him until he is quiet, she may teach him that if he cries he will get attention from mother. thus, the baby will learn to increase his crying in order to have his mother more. Every day, we grow and have new experiences. we constantly learn by reading, watching television, interacting with some people, and so forth. this learning affects our emotions. why is it that we learn to like some people and dislike others? if a person is nice to us, cares about us, we learn to associate this person with positive feelings, such as joy, happiness, and friendliness. on the other hand, if a person is mean to us, does not care about us, and even deliberately does things to harm us, we learn to associate this person with negative feelings, such as unhappiness, discomfort, and anger.（分数：20.00）(1).the author's main purpose in writing the passage is to _____ .（分数：4.00）A.teach children how to learn to produce and experience certain emotionB.give the general reader an account of two basic kinds of learningC.give parents some advice on how to modify their children's emotions through learningD.discuss with psychologist how positive and negative feelings are produced(2).if your jokes often find already echo in a person, you will learn though ____ that telling jokes to this person is fun, and you will try with greater efforts to be humorous in his presence. （分数：4.00）A.classical conditioningB.operant conditioningC.neither of themD.some other sorts of conditioning(3).if a child is bitten or startled several times by a dog, he may learn to associate furry animals with pain or startle and thus develop a fear of furry animals. this is a typical example of learning through ____. （分数：4.00）A.classical conditioningB.operant conditioningC.both of themD.neither of them(4).in the third paragraph, the author is ____.（分数：4.00）A.discussing how we grow and have new experiences every dayB.talking about learning to modify emotions through operant conditioningC.concentrating on learning by reading, watching television, interacting with people, and so oning examples to further illustrate learning through classical conditioning(5).in the following paragraphs the author will most probably go on to discuss _____.（分数：4.00）A.definitions of positive feelings and negative feelingsB.the third kind of learningC.further examples of learning through operant conditioningD.none of the aboveAny country has good reason to want its citizens to be as healthy as possible, since one of its greatest resources is an active population. No country wants its people to suffer unnecessarily from ill health. This was the kind of thinking which led to the introduction of a health service in many countries. In Britain this has developed into a “Welfare State” in which all citizens, rich and poor alike, can get most health treatment free. The money for this is partially raised by contributions from employers and employees. As three decades have shown, such automatic arrangements are not always ideal and there are arguments for and against the Health Service. The number of patients treated every year and the cost of treatment are much greater than was estimated. This means that the people who work for the Health Service—doctors, nurses and other hospital staff—have much more routine work to do and as a result they have little time for preventive medicine. The Health Service does need more staff—a need that can only be met if more money is made available to it. However, a powerful argument for the Health Service is that many people are able to receive expensive treatment which they could never afford themselves. Sometimes this free treatment is abused and people visit their doctors when they don’t really need to. Because they have so many patients, doctors cannot spend as long with each one as they would like, and some people prefer to pay for private treatment so that their doctors can give them more time. In fact, some wealthy people feel that they should pay, and so free more money for treatment to others. （分数：20.00）(1).In the author’s view, Britain is a Welfare State in that ______. （分数：4.00）A.all citizens are entitled to a free medical treatment in some senseB.poor, unlike the rich, could enjoy free medical treatmentC.health service is highly developed in BritainD.Britain doesn’t allow its people to suffer unnecessarily from ill health(2).We can infer from the passage that ______. （分数：4.00）A.the Health Service is introduced to many other countries by BritainB.the Health Service has been introduced and developed for 30 years in BritainC.an active population is the greatest resource in BritainD.all citizens in Britain have a good opinion of the Health Service(3).The best title for the passage would be ______. （分数：4.00）A.A Welfare StateB.Importance of the Health ServiceC.Disadvantages of the Health ServiceD.The Health Service(4).The author mentions that some wealthy people prefer to pay for private treatment because ____. （分数：4.00）A.their doctors can give them more time leave from workB.those doctors have better medical instrumentsC.they might save some money for the poorD.their doctors have a stronger sense of responsibility for the patients(5).The word “abused” (Par. 4) means ____. （分数：4.00）A.destroyeded in wrong wayC.ignoredD.wastedDo we need laws that prevent us from running risks with our lives? If so, then perhaps laws are needed prohibiting the sale of cigarettes and alcoholic drinks. Both products have been known to kill people. The hazards of drinking too much alcohol are as bad or worse than the hazards of smiking too many cigarettes. All right then, let's pass a law closing the liquor stores and the bars in this country. Let's put an end once and for all to the ruinous disease from which as many as 10 million Americans currently suffer--alcoholism. But wait. We've already tried that. For 13 years, between 1920 and 1933, there were no liquor stores anywhere in the United States. They were shut down abilished by an amendment to the Constitution and by a law of Congress. After January 20, 1920, there was supposed to be no more manyfacturing, selling, or transporting of "intoxicating liquors". Without any more liquor, people could not drink it. And if they did not drink it, how could they get drunk? There would be no more dangers to the public welfare from drunkenness and alcoholism. It was all bery logical. And yet prohibition of liquor, beer, and wine did not work. Why? Because, law or no law, millions of people still liked to drink alcohol. And they were willing to take risks to get it. They were not about to change their tastes and habits just because of a change in the law. And gans of liquor smugglers millions of gallons of the outlawed beverages across the Canadian and Mexican borders. Drinkers were licky to know of an illegal bar that served Mexican or Canadian liquor. Crime and drunkenness were both supposed to decline as a rusult of prohibition. Instead, people drank nore alcohol than ever-often poisoned alcohol. （分数：20.00）(1).Which of the following was NOT characteristic reason for the proposal of the 18th Amendment to the Constitution and the Volstead Act? （分数：4.00）A.There would be no further danger to the public from alcoholism.B.There would be a rise in the cost of alcoholic beverages.C.Without liquor, people would not drink.D.People would not become drunk of create a public nuisance.(2).During Prohibition, illegal alcohol was _____. （分数：4.00）A.sold openlyB.no longer a temptationC.a major factor in the passage of the Volstead ActD.brought across the Mexican and Canadian borders(3).During Prohibition, people _____. （分数：4.00）A.lived in fear of the lawB.were willing to risk arrest for the pleasure of liquorC.recklessly endangered their comunitiesD.were respectful of the legal sanctions placed on them(4).When enacting the prohibition law, government officials assumend that _____. （分数：4.00）A.every American would buy alcohol illegallyB.all criminal activities would ceaseC.patrols of the Canadian border would halt the sale of alcoholD.the social threat from drunkerness would decline(5).It can be inferred from the passage that _____. （分数：4.00）A.the Congress was wise to repeal ProhibitionB.the Prohibition Era was characterized by a decrease in crime and drunkennessC.during Prohibition, most Americans stopped drinkingws should be passed to ban the sale of alcoholic beveragesAs people continue to grow and age, our body systems continue to change. At a certain point in your life, your body system began to weaken. Your joint may become stiff. It may become more difficult for you to see and hear. The slow change of aging causes our bodies to lose some oftheir ability to bounce back from disease and injury. In order to live longer, we have always tried to slow or stop this process that leads us toward the end of our lives. Many factors contribute to your health. A well-balanced diet plays an important role. The amount and type of exercises you get is another factor. Your living environment and the amount of stress you are under is yet another. But scientists studying senescence want to know: Why do people grow old? They hope that by examining the aging process on a cellular level medical science may be able to extend the length of life. There is nothing to be afraid of as old age approaches. Many consider the later portions of life to be the best time for living. Physical activity may lessen, but often you gain a broader understanding of yourself and the world. What we consider old age now may only be middle-aged someday soon. Who knows with so many advances in medical science happening so quickly, life spans may one day be measured in centuries, rather than in years! （分数：20.00）(1).When people become aging, they will lose some of their ability to bounce back from disease and injury, “bounce back” here means _____. （分数：4.00）A.to improve in health after one?s disease and injuryB.to run fastC.to recover from disease and injuryD.to jump after recovering(2).In order to live longer, ______. （分数：4.00）A.we should postpone the process of agingB.we should try to do some exerciseC.we have to try to be on a dietD.we should keep in high spirits(3).Why are some scientists interested in studying senescence? ______ （分数：4.00）A.They may be able to find better ways to our lifeB.If they pin down the biochemical process that makes us age, there will be hope for extending the length of lifeC.They want find out if there is a link between how efficiently a cell could repair itself and how long a creature livesD.They want to increase the general ability of our bodies(4).Many consider the later portions of life to be the best time of living, because ______. （分数：4.00）A.they have a very good understanding of themselves and the outside worldB.they have nothing to do all day long only to watch their grandchildren growing up around themC.they have come through the battle of life safelyD.they consider their life has been a successful one(5).According to the passage, “spans” means _____.（分数：4.00）A.a long period of timeB.a length of timeC.a long distance from one place to anotherD.longevity翻译11. 2013年12月份以来，中国25个省份、100多座大中城市再次遭遇雾霾侵袭。
电力系统博士入学考试必备-电力系统复杂故障分析
电力系统博士入学考试必备-电力系统复杂故障分析相分量法和序分量法各自的特点，以及相互的区别和联系序分量法的原理对称分量法的特点（相对于其他序分量法）序分量法和相分量法在进行复杂故障分析时的流程。
对同步发电机的数学模型进行派克变换的数学和物理意义是什么？（05A）对同步发电机的数学模型进行派克（Park）变换的数学和物理意义是什么？（03A）写出dp0坐标下的同步发电机的磁链方程和电压方程，简述派克（Park）变换在同步发电机建模及分析中的作用是什么？（04电科院）相分量法和序分量法各自的特点，以及相互的区别和联系1)相分量是客观存在的。
因此相分量法能够准确地反映电力网络的所有实际问题，故障处理方法直观实用。
2)由于相坐标空间里元件参数存在耦合的问题，相分量计算方法的计算量比较大，同时复杂的耦合关系也使得相分量法在网络处理上不同于单相的情况，比采用单相网络的分析计算技术要困难得多。
方便的系统运行描述和准确地系统参数仿真是相分量法最大的优势。
国外许多大型研究机构都将相分量法作为主要的计算工具。
一个著名的例子就是EMTP。
1)序分量是相分量经过数学变换得到的。
序分量法通过坐标变换使在相坐标空间存在三相耦合关系的对称元件在序分量坐标空间得到解耦，2)在完全由对称元件组成的系统中，耦合的三相网络可以等效成三个独立的序分量对称网络，在网络分析方面与三个单相网络相同，可以使用单相网络分析的方法进行处理，并且能够大幅度简化计算。
3)序分量法因为模型简单、算法组织性强和计算速度快而得到了更广泛的认同，在更多的实用化的电力系统分析计算软件包中得到了应用。
序分量法中最经典的就是对称分量法，对称分量法可以方便地通过序网连接方式的改变而实现单一不对称简单故障，但是对于任意复杂故障，序网的边界条件不易实现，同时序网的连接方式随故障的不同而变化，不利于程序的实现。
相分量法能够轻松地处理任意的复杂故障，程序实现也极其方便。
对于一些不对称情况，都会在序网序网坐标空间内解耦失败，从而不能实现序网分离，序网法因此遭受严重影响。
2010年硕士初试电力系统分析基础试题A及答案
附件3：试题规范格式（命题人员请直接在文本中添加试题内容，打印前请删除本行）华北电力大学2010年硕士研究生入学考试初试试题考试科目：电力系统分析基础 A（或B）共页考生注意：答案必须写在答题纸上以下为试题内容：（五号宋体）一、不定项选择题（每题1分，共15分）1、ACD2、ABCDE3、ABC4、B5、A6、A7、AC8、C9、ABCD10、 C11、 B12、 C13、 A14、 B15、 C二、填空题（每空1分，共15分）16、 Y ＝Z -1 N ×N稀疏性 对称性 满阵17、电压用直角坐标描述时，潮流方程为电压用极坐标描述时，潮流方程为18、 有功功率 19、 无功功率20、 日负荷曲线 年最大负荷曲线 21、 相量差 有效值之差 标称电压 22、有名制 标么制三、简答和简单计算题（共40分）23、 （10分）牛顿法的数学基础是什么？参考答案：牛顿法的理论基础是通过将非线性方程一阶泰勒展开，近似为一个线性方程。
对于一个非线性方程，即()0f x =，如果给定初值0x ，那么在该点用泰勒级数展开后忽略x ∆的高次项，则有：00()()()()0x Tf x f x f x x f x x x ∂=+∆=+∆=∂010()()x Tf x x f x x -∂⎡⎤⇒∆=-⎢⎥∂⎣⎦因此得到牛顿法的迭代方程。
24、 （10分）在潮流计算中，什么是参考节点，什么平衡节点，分别起什么作用？参考答案：参考节点就是各节点电压的参考点也可以说是所选定的坐标原点，一般以大地作为参考点。
平衡节点是电压和相角都给定，注入有功和无功功率没有给定的节点。
参考节点，是因为第一电势都是相对值，没有绝对概念，因此选择一个电压的参考点。
第二，如果不去掉参考节点，那么节点导纳矩阵是奇异的，说明方程是多解的。
因为通常所说的电压，是以零电势点为参考电势点的，因此大地是作为参考节点，实际存在的。
而平衡节点的选择，主要目的是为了求解方程。
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2010的电力我只知道三道大题是考的什么,具体的数值肯定不知道了
电力分为选择、填空、三个大题
选择、填空好像就有60分了，三道大题40分
选择、填空（据师兄说很简单）都是课本上的
第一道大题：求解电网节点的导纳矩阵
二：不对称故障的分析计算，三相短路电流的计算以及其他类型的不对称短路计算
三：电力系统稳定分析(论述题)，不用计算
浙江大学2011年博士生入学考试电力系统分析试题
1、填空题，比较简单，书上一些概念
2、（1）什么是电力系统中性点，有那种？有什么区别和作用
（2）提高静态稳定和暂态稳定的措施有哪些？优缺点是什么？
3、求矩阵导纳，其中包括变压器的 变换
4、求电力系统的标幺值，
填空、判断、单选，这三种题里面都是基本的概念，没有计算。
计算：
1、导纳矩阵的修改：两节点间增加一条支路、从一个节点新增一条变压器支路
2、小干扰稳定性分析（包含励磁模型，何仰赞华中科技大学电力系统分析的书上有）
浙江大学2014年博士生入学考试电力系统分析试题
一、单项选择题
总共50分，10道题。
考察的比较多，也比较杂。
如问暂态稳定计算是用的什么微分方程（选项有常微分方程、偏微分方程等）；
问500KV输电线路的自然阻抗大约多少，有选项可选的；
问谐波滤波是属于电磁暂态、机电暂态还是什么过程；
问高压输电能减小输电损耗的原理；
其他的记不清了。
二、计算题
发电机的电磁功率特性计算。
利用有关功率平衡，有关公式计算发电机电磁功率型的计算题。
这题要在熟知《电力系统分析》（何仰赞，温增银，下册）中的第16章例题16-1，例题16-2的基础上，才能会计算。
三．问答题
1、电力系统中提高输电线路输电功率的措施有哪些。
2、电力系统中发电机上安装的控制有哪些，分别阐述。