电气专业英语论文

标准文档外文翻译院（系）专业班级姓名学号指导教师年月日Programmable designed for electro-pneumatic systemscontrollerJohn F.WakerlyThis project deals with the study of electro-pneumatic systems and the programmable controller that provides an effective and easy way to control the sequence of the pneumatic actuators movement and the states of pneumatic system. The project of a specific controller for pneumatic applications join the study of automation design and the control processing of pneumatic systems with the electronic design based on microcontrollers to implement the resources of the controller.1. IntroductionThe automation systems that use electro-pneumatic technology are formed mainly by three kinds of elements: actuators or motors, sensors or buttons and control elements like valves. Nowadays, most of the control elements used to execute the logic of the system were substituted by the Programmable Logic Controller (PLC). Sensors and switches are plugged as inputs and the direct control valves for the actuators are plugged as outputs. An internal program executes all the logic necessary to the sequence of the movements, simulates other components like counter, timer and control the status of the system.With the use of the PLC, the project wins agility, because it is possible to create and simulate the system as many times as needed. Therefore, time can be saved, risk of mistakes reduced and complexity can be increased using the same elements.A conventional PLC, that is possible to find on the market from many companies, offers many resources to control not only pneumatic systems, but all kinds of system that uses electrical components. The PLC can be very versatile and robust to be applied in many kinds of application in the industry or even security system and automation of buildings.Because of those characteristics, in some applications the PLC offers to much resources that are not even used to control the system, electro-pneumatic system is one of this kind of application. The use of PLC, especially for small size systems, can be very expensive for the automation project.An alternative in this case is to create a specific controller that can offer the exactly size and resources that the project needs [3, 4]. This can be made using microcontrollers as the base of this controller.The controller, based on microcontroller, can be very specific and adapted to only one kind of machine or it can work as a generic controller that can be programmed as a usual PLC and work with logic that can be changed. All these characteristics depend on what is needed and how much experience the designer has with developing an electronic circuit and firmware for microcontroller. But the main advantage of design the controller with the microcontroller is that the designer has the total knowledge of his controller, which makes it possible to control the size of the controller, change the complexity and the application of it. It means that the project gets more independence from other companies, but at the same time the responsibility of the control of the system stays at the designer hands2. Electro-pneumatic systemOn automation system one can find three basic components mentioned before, plus a logic circuit that controls the system. An adequate technique is needed to project the logic circuit and integrate all the necessary components to execute the sequence of movements properly.For a simple direct sequence of movement an intuitive method can be used [1, 5], but for indirect or more complex sequences the intuition can generate a very complicated circuit and signal mistakes. It is necessary to use another method that can save time of the project, makea clean circuit, can eliminate occasional signal overlapping and redundant circuits. The presented method is called step-by-step or algorithmic [1, 5], it is valid for pneumatic and electro-pneumatic systems and it was used as a base in this work.The method consists of designing the systems based on standard circuits made for each change on the state of the actuators, these changes are called steps.The first part is to design those kinds of standard circuits for each step, the next task is to link the standard circuits and the last part is to connect the control elements that receive signals from sensors, switches and the previous movements, and give the air or electricity to the supply lines of each step. In Figs. 1 and 2 the standard circuits are drawn for pneumatic and electro-pneumatic system [8]. It is possible to see the relations with the previous and the next steps.3. The method applied inside the controllerThe result of the method presented before is a sequence of movements of the actuator that is well defined by steps. It means that each change on the position of the actuators is a new state of the system and the transition between states is called step.The standard circuit described before helps the designer to define the states of the systems and to define the condition to each change betweenthe states. In the end of the design, the system is defined by a sequencethat never chances and states that have the inputs and the outputs well defined. The inputs are the condition for the transition and the outputs are the result of the transition.All the configuration of those steps stays inside of the microcontroller and is executed the same way it was designed. The sequences of strings are programmed inside the controller with 5 bytes; each string has the configuration of one step of the process. There are two bytes for the inputs, one byte for the outputs and two more for the other configurations and auxiliary functions of the step. After programming, this sequence of strings is saved inside of a non-volatile memory of the microcontroller, so they can be read and executed.The controller task is not to work in the same way as a conventional PLC, but the purpose of it is to be an example of a versatile controller that is design for an specific area. A conventional PLC process the control of the system using a cycle where it makes an image of the inputs, execute all the conditions defined by the configuration programmed inside, and then update the state of the outputs. This controller works in a different way, where it read the configuration of the step, wait the condition of inputs to be satisfied, then update the state or the outputs and after that jump to the next step and start the process again.It can generate some limitations, as the fact that this controller cannot execute, inside the program, movements that must be repeated for some time, but this problem can be solved with some external logic components. Another limitation is that the controller cannot be applied on systems that have no sequence. These limitations are a characteristic of the system that must be analyzed for each application.4. Characteristics of the controllerThe controller is based on the MICROCHIP microcontroller PIC16F877 [6,7] with 40 pins, and it has all the resources needed for thisproject .It has enough pins for all the components, serial communication implemented in circuit, EEPROM memory to save all the configuration of the system and the sequence of steps. For the execution of the main program, it offers complete resources as timers and interruptions.The list of resources of the controller was created to explore all the capacity of the microcontroller to make it as complete as possible. During the step, the program chooses how to use the resources reading the configuration string of the step. This string has two bytes for digital inputs, one used as a mask and the other one used as a value expected. One byte is used to configure the outputs value. One bytes more is used for the internal timer , the analog input or time-out. The EEPROM memory inside is 256 bytes length that is enough to save the string of the steps, with this characteristic it is possible to save between 48 steps （Table 1）.The controller (Fig.3) has also a display and some buttons that are used with an interactive menu to program the sequence of steps and other configurations.4.1. Interaction componentsFor the real application the controller must have some elements to interact with the final user and to offer a complete monitoring of the system resources that are available to the designer while creating the logic control of the pneumatic system (Fig.3):•Interactive mode of work; function available on the main program for didactic purposes, the user gives the signal to execute the step. •LCD display, which shows the status of the system, values of inputs, outputs, timer and statistics of the sequence execution.•Beep to give important alerts, stop, start and emergency.• Leds to show power on and others to show the state of inputs and outputs.4.2. SecurityTo make the final application works property, a correct configuration to execute the steps in the right way is needed, but more then that itmust offer solutions in case of bad functioning or problems in the execution of the sequence. The controller offers the possibility to configure two internal virtual circuits that work in parallel to the principal. These two circuits can be used as emergency or reset buttons and can return the system to a certain state at any time [2]. There are two inputs that work with interruption to get an immediate access to these functions. It is possible to configure the position, the buttons and the value of time-out of the system.4.3. User interfaceThe sequence of strings can be programmed using the interface elements of the controller. A Computer interface can also be used to generate the user program easily. With a good documentation the final user can use the interface to configure the strings of bytes that define the steps of the sequence. But it is possible to create a program with visual resources that works as a translator to the user, it changes his work to the values that the controller understands.To implement the communication between the computer interface and the controller a simple protocol with check sum and number of bytes is the minimum requirements to guarantee the integrity of the data.4.4. FirmwareThe main loop works by reading the strings of the steps from the EEPROM memory that has all the information about the steps.In each step, the status of the system is saved on the memory and it is shown on the display too. Depending of the user configuration, it can use the interruption to work with the emergency circuit or time-out to keep the system safety. In Fig.4,a block diagram of micro controller main program is presented.5. Example of electro-pneumatic systemThe system is not a representation of a specific machine, but it is made with some common movements and components found in a real one. The system is composed of four actuators. The actuators A, B and C are double acting and D-single acting. Actuator A advances and stays in specified position till the end of the cycle, it could work fixing an object to the next action for example (Fig. 5) , it is the first step. When A reaches the end position, actuator C starts his work together with B, making as many cycles as possible during the advancing of B. It depends on how fastactuator B is advancing; the speed is regulated by a flowing control valve. It was the second step. B and C are examples of actuators working together, while B pushes an object slowly, C repeats its work for some time.When B reaches the final position, C stops immediately its cycle and comes back to the initial position. The actuator D is a single acting one with spring return and works together with the back of C, it is the third step. D works making very fast forward and backward movement, just one time. Its backward movement is the fourth step. D could be a tool to make a hole on the object.When D reaches the initial position, A and B return too, it is the fifth step.Fig. 6 shows the first part of the designing process where all the movements of each step should be defined [2]. (A+) means that the actuator A moves to the advanced position and (A−) to the initial position. The movements that happen at the same time are joined together in the same step. The system has five steps.These two representations of the system (Figs. 5 and 6) together are enough to describe correctly all the sequence. With them is possible to design the whole control circuit with the necessary logic components. But till this time, it is not a complete system, because it is missing some auxiliary elements that are not included in this draws because they work in parallel with the main sequence.These auxiliary elements give more function to the circuit and are very important to the final application; the most important of them is the parallel circuit linked with all the others steps. That circuit should be able to stop the sequence at any time and change the state of the actuators to a specific position. This kind of circuit can be used as a reset or emergency buttons.The next Figs. 7 and 8 show the result of using the method without the controller. These pictures are the electric diagram of the control circuit of the example, including sensors, buttons and the coils of the electrical valves.The auxiliary elements are included, like the automatic/manual switcher that permit a continuous work and the two start buttons that make the operator of a machine use their two hands to start the process, reducing the risk of accidents.6. Changing the example to a user programIn the previous chapter, the electro-pneumatic circuits were presented, used to begin the study of the requires to control a system that work with steps and must offer all the functional elements to be used in a real application. But, as explained above, using a PLC or this specific controller, the control becomes easier and the complexity can be increasealso.Table 2 shows a resume of the elements that are necessary to control the presented example.With the time diagram, the step sequence and the elements of the system described in Table 2 and Figs. 5 and 6 it is possible to create the configuration of the steps that can be sent to the controller (Tables 3 and 4).While using a conventional PLC, the user should pay attention to the logic of the circuit when drawing the electric diagram on the interface (Figs. 7 and 8), using the programmable controller, described in this work, the user must know only the concept o f the method and program only the configuration of each step.It means that, with a conventional PLC, the user must draw the relationbetween the lines and the draw makes it hard to differentiate the steps of the sequence. Normally, one needs to execute a simulation on the interface to find mistakes on the logicThe new programming allows that the configuration of the steps be separated, like described by the method. The sequence is defined by itself and the steps are described only by the inputs and outputs for each step.The structure of the configuration follows the order:1-byte: features of the step;2-byte: mask for the inputs;3-byte: value expected on the inputs;4-byte: value for the outputs;5-byte: value for the extra function.Table 5 shows how the user program is saved inside the controller, this is the program that describes the control of the example shown before.The sequence can be defined by 25 bytes. These bytes can be dividedin five strings with 5 bytes each that define each step of the sequence (Figs. 9 and 10).7. ConclusionThe controller developed for this work (Fig. 11) shows that it is possible to create a very useful programmable controller based on microcontroller. External memories or external timers were not used in case to explore the resources that the microcontroller offers inside. Outside the microcontroller, there are only components to implement the outputs, inputs, analog input, display for the interface and the serial communication.Using only the internal memory, it is possible to control a pneumatic system that has a sequence with 48 steps if all the resources for all steps are used, but it is possible to reach sixty steps in the case of a simpler system.The programming of the controller does not use PLC languages, but a configuration that is simple and intuitive. With electro-pneumatic system, the programming follows the same technique that was used before to design the system, but here the designer work s directly with the states or steps of the system.With a very simple machine language the designer can define all the configuration of the step using four or five bytes. It depends only on his experience to use all the resources of the controller.The controller task is not to work in the same way as a commercial PLC but the purpose of it is to be an example of a versatile controller that is designed for a specific area. Because of that, it is not possible to say which one works better; the system made with microcontroller is an alternative that works in a simple way.应用于电气系统的可编程序控制器约翰 F.维克里此项目主要是研究电气系统以及简单有效的控制气流发动机的程序和气流系统的状态。

电气工程及其自动化专业英语作文范文Electrical Engineering and Automation: An Integral Part of Modern SocietyIntroductionElectrical Engineering and Automation, a discipline that has evolved significantly over the past few decades, has become an integral part of modern society. Its widespread applications in industry, agriculture, national defense, and various other fields have propelled it to a pivotal position in the global economy.Historical PerspectiveThe field of Electrical Engineering and Automation was first established approximately forty years ago. As a relatively new discipline, it has quickly grown to encompass a wide range of subfields and applications. From the design of switches for aerospace aircraft to the development of complex automated systems, its influence is pervasive.Core ComponentsThe core of Electrical Engineering and Automation lies in its ability to integrate electricity, machines, and intelligent systems to automate various tasks. This integration enables efficiency, precision, and safety in a wide range of applications.•Electricity and Machines: Electricity provides the power that drives machines and systems. Understanding the behavior ofelectrical circuits, voltage sources, current sources, andvarious network elements is crucial for the effective designand operation of automated systems.•Automation: Automation refers to the use of technology to control and monitor processes and machines with minimal humanintervention. It relies on sensors, actuators, and intelligentcontrollers to achieve desired outcomes.Challenges and OpportunitiesWhile Electrical Engineering and Automation offers immense opportunities for growth and development, it also poses significantchallenges. The complexity of modern systems requires a high level of technical knowledge and expertise. Additionally, the rapid pace of technological advancement requires constant updating of skills and knowledge.However, these challenges also present opportunities for innovation and growth. As new technologies emerge, there is a need for engineers and technicians who can understand and apply them effectively. This creates opportunities for those with a passion for learning and a willingness to adapt to new challenges.ConclusionIn conclusion, Electrical Engineering and Automation is a dynamic and exciting field that offers immense opportunities for growth and development. Its applications are pervasive, and its influence on society is profound. As we continue to push the boundaries of technology, Electrical Engineering and Automation will play an increasingly important role in shaping our future.。

电气工程及其自动化专业英语课程论文Document serial number【NL89WT-NY98YT-NC8CB-NNUUT-NUT108】重庆邮电大学移通学院《电气工程及其自动化专业英语》课程论文年级 2012专业电气工程与自动化姓名孙猜胜学号Three-phase asynchronous motorAbstract:The three-phase asynchronous motor is motor's one with single phase asynchronous motor, three-phase asynchronous motor operating performance is good, and can save various the structure to be simple, the manufacture is easy, firm durable, the service is convenient,cost inexpensive ,drag the ability is good,and so on a series of merits. thus becomes in each kind of electrical machinery the outputto be biggest utilizes the broadest one kind of electric motor.Key words:Moror Motor starting Star delta StartingThree-phase asynchronous motor principle:When the stator winding through into the three-phase ac three-phase symmetric arises when a synchronous speed n1 along the stator and rotor round for space in a clockwise rotation magnetic field. Because of a rotating magnetic field rotating speed to n1, rotor conductor of the static beginning, so the rotor conductor will cutthe stator and produce a rotating magnetic field induction emf (induction emf direction DingZe judge with the right hand). Because the child is short circuit loop ends conductor short meet, in therole of the induced emf, will produce the rotor conductor with induction emf direction basic consistent induced current. The rotor current-carrying conductor at stator magnetic field is the role ofthe electromagnetic force (the direction of the force with the left hand DingZe judge). The electromagnetic force of the rotor axis electromagnetic torque, drive along the rotor rotating magnetic field rotation direction.[1]Through the above analysis can be summed up the motor principle: when the three-phase motor stator winding (eachdiffer 120 KWH Angle), ventilation with three-phase ac, will producea rotating magnetic field, the rotating magnetic field cutting rotor winding, and thus to the rotor winding induced current (rotor windingis closed access), load flow of rotor stator conductor under the action of a rotating magnetic field will produce the electromagnetic force, thus in the motor shaft formed on the electromagnetic torque, driving motor rotation, and motor rotation direction and the rotating magnetic field in the same direction.Thestructureofthree-phaseasynchronousmotor:Types of three-phase asynchronous motor, but all kinds of three-phase asynchronous motor is the same basic structure, they are the stator and rotor of these two basic components, the stator and rotor has a certain air gap between. In addition, end caps, bearings, cable boxes, rings and other accessories,1).StatorpartStator is used to generate the rotating magnetic Three-phase motors generally shell, stator core, stator windings and other parts.a.Shell?Three-phase motor casing including base,end caps,bearingcaps,rings,such as junction boxes and comp onentsb. Stator CoreInduction motor stator core is part of the motor circuit from ~ thick coated with a thin insulating paint from silicon,c.ThestatorwindingsThree-phase motor stator windings are part of the circuit,there are three-phase three-phase motor windings,summetrical three-phase current access,it will have a rotating magnetic winding consists of three separate components of the winding, and each has a number of coil windings a phase of each winding, each winding in the space angle difference between the 120 ° electrical[2].2). Rotor parta. Rotor CoreWith mm thick steel from, set in the shaft, the role and the same stator core, on the one hand, as part of the motor magnetic circuit, on the one hand to place the rotor windings.b. Rotor windingsThe rotor winding induction motor winding is divided into two kinds of cage-shaped and which is divided into winding rotor asynchronous motor with cage induction motor.3). Other parts ofOther parts including the cover, fans, etc.Induction motor starting methods:There are several general methods of starting induction motors: full voltage, reduced voltage,wyes-delta,and part winding reduced voltage type can include solid state starters, adjustable frequency drives, and following is the most common method.1).Full voltageThe full voltage starting method, also known as across the line starting, is the easiest method to employ, has the lowest equipment costs, and is the most reliable. This method utilizes a control to close a contactor and apply full line voltage to the motor terminals. This method will allow the motor to generate its highest starting torque and provide the shortest acceleration method also puts the highest strain on the power system due to the high starting currents that can be typically six to seven times the normal full load current of the motor.2).AutotransformerThe motor leads are connected to the lower voltage side of the transformer. The most common taps that are used are 80%, 65%, and 50%. At 50% voltage the current on the primary is 25% of the full voltage locked rotor amps. The motor is started with this reduced voltage,and then after a pre-set condition is reached the connection is switched to line voltage. This condition could be a preset time, current level, bus volts, or motor speed. The change over can be done in either a closed circuit transition, or an open circuit transition method. In the open circuit method the connection to the voltage is severed as it is changed from the reduced voltage to the line level. Care should be used to make sure that there will not be problems from transients due to the switching. This potential problem can be eliminated by using the closed circuit transition. With the closed circuit method there is a continuous Voltage applied to the motor. Another benefit with the autotransformer starting is in possiblelower vibration and noise levels during starting.3).Star delta StartingThis approach started with the induction motor,the structure of each phase of the terminal are placed in the motor teminal box ,This allows the motor star connection in the initial start up,and then re-connected into a triangle run..The initial start time when the voltage is reduced to the original star connection,the startingcurrent and starting torque by 2/3. Depending on the applicationon,the motor switch to the triangle in the rotational speed of between 50% and the maximum be noted that the sameproblems,including the previously mentioned switch method ,if theopen circuit method,the transition may be a transient method isoften used in lesst than 600V motor,the rated voltage and higher are not suitable for star delta motor start method.[3]4).Series Resistor or Reactor StartingThis method is to use a series resistance or place in the motor loop the motor is started, a resistor to limit current and make the motor at the input voltage drop. Therefore plays a role of limitingcurrent at the small motor series resistor startup mode used more frequentlyConclusion:There are many ways asynchronous motor starting, each method hasits own benefits, according to the constraints of powersystems,equipment costs, load the boot device to select the best method.References:[1] Tang Tianhao Fundamentals of Electrical Machines and Drives [M] BeijingChina Machine Press 118-137[2] Wang Liming English for Electrical Engineering and Automation [M] BeijingTsinghua University Press 61-64[3] Stephen Electromechanics [M] America Electronic IndustryPress 340-370。

(完整word版)电气工程及其自动化专业外语作文A s a student, you will learn to apply related subjects such as computer technology，industrial electronics, instrumentation，electrical machines, robotics，power electronics，and automated control systems.作为一名学生，你将学会运用相关学科,如计算机技术，工业电子，仪器仪表，电器机械，机器人技术，电力电子和自动化控制系统。

Y ou will be able to understand written and oral instructions，as well as design, install, test，modify, troubleshoot，and repair electrical systems.您将能够理解书面和口头说明，以及设计,安装，测试，修改，故障排除和修复电力系统.U pon graduation，students of the Electrical Engineering Technology –Process Automation program can approach industrial electrical and electronic systems from the viewpoint of analysis，technical evaluation, design, and development。

The six—semester program concentrates on the in-depth study of electrical and electronic principles as they apply to automated systems using programmable logic controllers。

电气工程专业介绍英语范文英文回答：Electrical engineering is a vast field comprising the application of electricity, electronics, and electromagnetism. It encompasses various subfields, including power generation, transmission, distribution, control, and utilization. Electrical engineers design, develop, and maintain complex systems and devices used in a wide array of applications, from household appliances to advanced telecommunications systems.They work in collaboration with other engineers and technicians to design, test, and implement electrical systems that meet specific requirements. Electrical engineers may specialize in areas such as power systems, control systems, electronics, or telecommunications. They are responsible for ensuring that electrical systems are safe, efficient, and reliable.Some of the key responsibilities of electrical engineers include:Designing and developing electrical systems for power generation, transmission, distribution, and control.Designing and installing electrical wiring and equipment for homes, businesses, and industrial facilities.Maintaining and repairing electrical systems and equipment.Troubleshooting electrical problems.Developing and testing new electrical technologies.Electrical engineers play a critical role in the development and maintenance of modern society. They are responsible for the design and operation of the electrical systems that power our homes, businesses, andtransportation systems. They also work in the development of new technologies, such as renewable energy systems andelectric vehicles.中文回答：什么是电气工程？电气工程是应用电、电子、电磁学的广阔领域。

电气专业毕业设计英文文献电气专业毕业设计英文文献外文资料与中文翻译外文资料:Relay protection present situation anddevelopment一、Relay protection development present situationElectrical power system's swift development to the relay protection proposed unceasingly the new request, the electronic technology, the computer technology and communication's swift development unceasingly has infused the new vigor for the relay protection technology's development, therefore, the relay protection technology is advantageous, has completed the development 4 historical stage in 40 remaining years of time.After the founding of the nation, our country relay protection discipline, the relay protection design, the relay factory industry and the relay protection technical team grows out of nothing, has passed through the path which in about 10 year the advanced countries half century pass through. In the 50s, our country engineers and technicians creatively absorption, the digestion, have grasped the overseas advanced relay protection equipment performance and the movement technology [1], completed one to have the deep relay protection theory attainments and the rich service experience's relay protection technical team, and grew the instruction function to the national relay protection technical team's establishment. The Achengrelay factory introduction has digested at that time the overseas advanced relay technique of manufacture, has established our country own relay manufacturing industry.Therefore our country has completed the relay protection research, the design, the manufacture, the movement and the teaching complete system in the 60s. This is the mechanical and electrical -like relay protection prosperous time, was our country relay protection technology development has laid the solid foundation.From the late 50s, the transistor relay protection was starting to study. In the 60s to the 80s in is the time which the transistor relay protection vigorous development and widely uses. And the Tianjin University and the Nanjing Electric power Automation Plant cooperation research's 500kv transistor direction high frequency protection develops with the Nanjing Electric power Automation Research institute the transistor high frequency block system is away from the protection, moves on the Gezhou Dam 500 kv lines [2], finished the 500kv line protection to depend upon completely from the overseas import time.From the 70s, started based on the integration operational amplifier's integrated circuit protection to study. Has formed the complete series to the late 80s integrated circuit protection, substitutes for the transistor protection gradually. The development which, the production, the application protected to the early 90s integrated circuit were still in the dominant position, this was theintegrated circuit protection time. The integrated circuit power frequency change quantity direction which develops in this aspect Nanjing Electric power Automation Research institute high frequency protected the influential role [3], the Tianjin University and the Nanjing Electric power Automation Plant cooperation development's integrated circuit phase voltage compensation type direction high frequency protection alsomoved in many 220kv and on the 500kv line.Our country namely started the computer relay protection research from the late 70s [4], the institutions of higher learning and the scientific research courtyard institute forerunner's function. Huazhong University of Science and Technology, the Southeast University, the North China electric power institute, Xi'an Jiaotong University, the Tianjin University, Shanghai Jiaotong University, the Chongqing University and the Nanjing Electric power Automation Research institute one after another has developed the different principle, the different pattern microcomputer protective device. in 1984 the original North China electric power institute developed the transmission line microcomputer protective device first through the appraisal, and obtained the application in the system [5], has opened in our country relay protection history the new page, protected the promotion for the microcomputer to pave the way. In the main equipment protection aspect, the generator which the Southeast University and Huazhong University of Science and Technology develops loses magnetism protection, the generator protection and the generator? Bank of transformers protectionalso one after another in 1989, in 1994 through appraisal, investment movement. The Nanjing Electric power Automation Research institute develops microcomputer line protective device alsoin 1991 through appraisal. Tianjin University and Nanjing Electric power Automation Plant cooperation development microcomputer phase voltage compensation type direction high frequency protection, Xi'an Jiaotong University and Xuchang relay factory cooperation development positive sequence breakdown component direction high frequencyprotection also one after another in 1993, in 1996 through appraisal. Hence, the different principle, the different type's microcomputer line and the main equipment protect unique, provided one group of new generation performance for the electrical power system to be fine, the function was complete, operation reliable relay protection installment. Along with the microcomputer protective device's research, in microcomputer aspects and so on protection software, algorithm has also made many theory progresses. May say that started our country relay protection technology from the 90s to enter the time which the microcomputer protected.二、future development of Relay protectionThe future trend of relay protection technology is to computerization, networking is intelligent, protect, control, measure and data communication developing by integration. The principles of protection of electric power circuits are quite independent of the relay designs which may be applied. For example, if the current to an electriccircuit or a machine is greater than that which can be tolerated, it is necessary to take remedial action. The device for recognizing the condition and initiating corrective measures would be termed as an over-current relay regardless of the mechanists by whichthe function would be accomplished. Because the functions of electromechanical devices are easily described, their performance wills ever as a basis for presenting a description of relays and relay systemsin general.Relays must have the following characteristics: Reliability---The nature of the problem is that the relay may be idle for periods extending into years and then be required tooperatewith fast responds, as intended, the first time. The penalty for failure to operate properly may run into millions of dollars.Selectivity---The relay must not respond to abnormal, but harmless, system conditions such as switching transients or sudden changes in load.Sensitivity---The relay must not fail to operate, even in borderline situations, when operation was planned.Speed---The relay should make the decision to act as close to instantaneously as possible. If intentional time delay is available, it should be predictable and precisely adjustable.Instantaneous---The term means no intentional time delay.There are several possible ways to classify relays: by function, by construction, by application. Relays are one of two basic types of construction: electromagnetic or solid-state. The electromagnetic type relies on the development of electromagnetic forces on movable members,which provide switching action by physically opening or closing sets of contacts. The solid state variety provides switching action with no physical motion by changing the state of serially connected solid state component from no conducting to conducting(or vice versa). Electromagnetic relays are older and more widely used; solid state relays are more versatile, potentially more reliable, and fast.1)ComputerizationWith swift and violent development of computer hardware, computer protect hardware develop constantly even. The power system is improving to the demand that the computer protects constantly, besides basic function protected, should with trouble information of the large capacity and data the long-term parkingspace also, fast data processing function, strong communication capacity, network in order to share the whole system data , information , ability , network of resource with other protection , control device , dispatcher, high-level language programming ,etc.. This requires computer protector to have function which is equivalent to a pc machine. In computer is it develop initial stage to protect, is it make with one minicom relay protection install to imagine. Because the small-scale organism was accumulated greatly, with high costs at that time, dependability was bad, this imagined it was unrealistic . Now, exceed the minicomputer of those years greatly with computer protector size similar worker function , speed , memory capacity of accusing of machine, so make with complete sets of worker person who accuse of opportunity of relay protection already ripe, this will be one of the developing direction that a computer is protected . Tianjin university is it spend whom transformation act as continue the electric protector with computer protector structure self-same one worker person whoaccuse of to develop into already. The advantage of this kind of device is as follows, (1)it have functions of 486pc,it can meet to at present and it is various kinds of function demand where computerprotect future. (2)The size and structure are similar to present computer protector , the craft is superior, takes precautions against earthquakes , defends overheatedly and defending the electromagnetic ability of interfering strongly, can operate it in very abominable working environment , the cost is acceptable.(3)Adopting std bus or pc bus, hardware module , can select different module for use to different protection wantonly , it is flexible , easy to expand to dispose.It is an irreversible development trend to continue the computer , computerization of the electric protector. But to how better meet power system demand, how about raise the dependability of relay protection further, how make heavy economic benefits and social benefit, need carry on concrete deep research.2) NetworkedComputer network become the technological pillar of information age as message and data communication tool, made the mankind producing , basic change has taken place in the appearance with social life. It isinfluencing each industrial field deeply, has offered the powerful communication means for each industrial field too. Up till now, except that protect differentially and unite protecting vertically, all continue electric protector can only react that protect the electric quantity of installing office. The function of relay protection is only limited to excising the trouble component too , narrow the accident coverage. This mainly lack the powerful data communication means. Having already put forward the concept protected systematically abroad, this meant the safe automatics mainly at that time. Because the function of relay protection is not only limited to excising the trouble component and restriction accident coverage (this is primary task), the peace and steadiness that will be guaranteed the whole system run . This require each protect unit can share the whole operation and data , trouble of information of system, each protect unit and coincident floodgate device coordination on the basis of analysing the information and data, guarantee systematic peace and steadiness run . Obviously , realize the primary condition that system protect the whole system every protector of capitalequipment link with the computer network, namely the one that realized the computer protector is networked. This is totally possible under present technological condition .To general protecting systematically , realize the computer networking of the protector has a very great advantage too. It continue electric trouble not the less many in information not systematic can receiving protector ,for trouble nature , judgement and the trouble,trouble of position from measuring the less accurate. Protect to self-adaptation research of principle pass long time very already , make certain achievement too, but should really realize protecting the self-adaptation to the operation way of the system and trouble state, must obtain more system operating and trouble information , the computer that only realizes protecting is networked, could accomplish this . As to the thing that some protectors realize computer networking , can improve the dependability protected . Tianjin Sanxia vltrahigh voltage many return circuit bus bar , 500kv of power station , put forward one distributed principle that bus bar protected to future 1993 such as university, succeed in developing this kind of device tentatively. Principle its bus bar is it disperse several (with protect into bus bar back to way the same ) bus bar protect Entrance to protect traditional concentration type, disperse and install it in every return circuit is protected and rejected , each protect the unit to link with the computer network, each one protects the electric current amount that the unit only inputs a return circuit , after changing it into figure amount, convey to the protection units of other return circuits through the computer network, each protect the unit according to the electric current amount of this return circuit and electric current amount of other return circuits gotfrom computer network, carry on bus bar differential calculation that protect, if result of calculation prove bus bar trouble jump format return circuit circuit breaker only, isolate the bus bar of the trouble. At the time of the trouble outside the bus bar district , each protect the unit and calculate for movements of the external trouble. This kind protect principle by distributed bus barthat network realize with computer, bus bar protect principle have higher dependability than traditional concentration type. Because if one protect unit interfere or mistake in computation and when working up by mistake, can only jump format return circuit , can is it make bus bar to be whole of malignant accident that excise to cause wrong, this is very important to systematic pivot with supervoltage bus bar of hydropower station like SanxiaCan know computer protector networked to can raise and protect the performance and dependability greatly while being above-mentioned, this is an inexorable trend that a computer protects development 3) Protect , control , measure , data communication integratesOn terms that realize computerization of relay protection and networked, the protector is a high performance , multi-functional computer in fact, it is a intelligent terminal on the computer network of whole power system. It can obtain any information and data of operating and trouble of the power system from network , can convey network control centre or any terminal function , and can also finish the measurement , control , data communication function in there is no normal running of trouble cases, namely realize protecting ,controlling , measuring , data communication integrates.At present, for measurement, need that protects and controlling, all equipment of the outdoor transformer substation, two voltage, electric current of voltage transformer, circuit,etc. must with control cable guide to the top management room for instance. Lay control cable take a large amount of investment, make the very much complicated returncircuit 2 times in a large amount. But if above-mentioned protection, control, measure, data communication integrated computer device, install in to is it by the equipment , protect into voltage , electric current amount of equipment in device this after changing into the figure amount to protect outdoor transformer substation on the spot, send to the top management room through the computer network, can avoid a large number of controlcables . If use optic fibre as the transmission medium of the network , can avoid and interfere electromagnetically. The photocurrent mutual inductor of now (ota ) and photovoltage mutual inductor (otv ) have been already during the course of studying and testing, must get application in the power system in the future. In case of adopting ota and otv, namely should be putting and is being protected near the equipment.After the optical signals of ota and otv are input in the integrated device here and changes into an electric signal, what is on one hand uses as being protected calculation is judged ; As measurement amount on the other hand, send to the top management room through the network. Can to protect operation of equipment control order send this integrated device to through network from top management room, therefore the integrated device carries out the operation of the circuit breaker. The university of Tianjin put forward protecting,controlled , measured , communication integration in 1992, develop based on tms320c25 digital signal processor (dsp ) first protecting , control , measure , the integrated device of data communication.4)IntelligentIn recent years, if artificial intelligence technology neural network, hereditary algorithm, evolve plan , fuzzy logic ,etc. get application in power system all field, the research that is used in the field of relay protection has already begun too. Neural network one non-linear method that shine upon, a lot of difficult to list equation or difficult in order to the complicated non-linear question that is solved, use the method of the neural network to be very easily solved .For example the short circuit of crossing the resistance of courseof emergence is a non-linear problem in transmit electricity in the systematic electric potential angle of both sides of line and lay cases, it is very difficult to make discrimination , trouble of position while being correct for distance to protect, is it work up or is it work up to refuse by mistake to lead to the fact; If use neural network method, through a large number of trouble training of sample, so long as sample centralized to fully consider various kinds of situations, can differentiate correctly while any trouble takes place. Other if hereditary algorithm , is it is it have is it solve complicated abilityof problem to asking unique their too to plan to evolve. Artificial intelligence the being method proper to is it can make it solve speed to be fast not to ask to combine. Can predict , the artificial intelligence technology must get application in the field of relay protection, in order to solve the problem difficult to solvewith the routine method.中文翻译:继电保护的现状与发展一、继电保护发展现状电力系统的飞速发展对继电保护不断提出新的要求，电子技术、计算机技术与通信技术的飞速发展又为继电保护技术的发展不断地注入了新的活力，因此，继电保护技术得天独厚，在40余年的时间里完成了发展的4个历史阶段。

英语作文电气类专业知识Electrical Engineering。

Electrical engineering is a field of study that deals with the design, development, and maintenance of electrical systems. These systems can include anything from power generation and distribution to communication networks and electronic devices. Electrical engineers are responsiblefor designing and implementing these systems, as well as ensuring that they operate safely and efficiently.One of the key areas of focus in electrical engineering is power generation and distribution. This involves designing and building power plants, transformers, and other equipment that is necessary to generate anddistribute electricity. Electrical engineers must also ensure that the electrical grid is reliable and can handle the demands of a growing population.Another important area of electrical engineering iscommunication networks. This includes designing and building telecommunications systems, such as cell phone networks and internet infrastructure. Electrical engineers must also ensure that these systems are secure and can handle the increasing demands of modern communication.Electronic devices are another area of focus in electrical engineering. This includes designing and building everything from computer hardware to medical equipment. Electrical engineers must ensure that these devices are efficient, reliable, and safe to use.In addition to these areas of focus, electrical engineering also involves research and development. This can include developing new technologies and improving existing ones. Electrical engineers must stay up to date with the latest advancements in their field and be able to apply this knowledge to their work.Overall, electrical engineering is a challenging and rewarding field of study. It requires a strong understanding of mathematics and physics, as well as acreative and innovative mind. Electrical engineers have the opportunity to make a significant impact on the world by designing and building the systems that power our lives.。

Power Supply and Distribution SystemABSTRACT: The basic function of the electric power system is to transport the electric power towardscustomers..The l0kV electric distribution net is a key point that connects the power supply with the electricityusing on the industry, business and daily-life. For the electric power, allcostumers expect to pay the lowest price for the highest reliability, but don't consider that it's self-contradictory in the co-existence of economy and reliable.To improve the reliability of the power supply network, we must increase the investment cost of the network construction But, if the cost that improve the reliability of the network construction, but the investment on this kind of construction would be worthless if the reducing loss is on the power-off is less than the increasing investment on improving the reliability .Thus we find out a balance point to make the most economic,between the investment and the loss by calculating the investment on power net and the loss brought from power-off.KEYWORDS:power supply and distribution, power distribution reliability，reactive compensation, load distributionThe revolution of electric power system has brought a new big round construction,which is pushing the greater revolution of electric power technique along with the application of new technique and advanced equipment. Especially, the combination of the information technique and electric power technique, to great ex- tent, has improved reliability on electric quality and electric supply. The technical development decreases the cost on electric construction and drives innovation of electric network. On the basis of national and internatio- nal advanced electricknowledge, the dissertation introduces the research hotspot for present electric power sy- etem as following.Firstly, This dissertation introduces the building condition of distribution automation(DA), and brings forward two typical construction modes on DA construction, integrative mode and fission mode .It emphasize the DA structure under the condition of the fission mode and presents the system configuration, the main station scheme, the feeder scheme, the optimized communication scheme etc., which is for DA research reference.Secondly, as for the (DA) trouble measurement, position, isolation and resume, This dissertation analyzes the changes of pressure and current for line problem, gets math equation by educing phase short circuit and problem position under the condition of single-phase and works out equation and several parameter s U& , s I& and e I& table on problem . It brings out optimized isolation and resume plan, realizes auto isolation and network reconstruction, reduces the power off range and time and improves the reliability of electric power supply through problem self- diagnoses and self-analysis. It also introduces software flow and use for problem judgement and sets a model on network reconstruction and computer flow.Thirdly, electricity system state is estimated to be one of the key techniques in DA realization. The dissertation recommends the resolvent of bad measurement data and structure mistake on the ground of describing state estimate way. It also advances a practical test and judging way on topology mistake in state estimate about bad data test and abnormity in state estimate as well as the problem and effect on bad data from state measure to state estimate .As for real time monitor and control problem, the dissertation introduces a new way to solve them by electricity break and exceptional analysis, and the way has been tested in Weifang DA.Fourthly, about the difficulty for building the model of load forecasting, big parameter scatter limit and something concerned, the dissertation introduces some parameters, eg. weather factor, date type and social environment effect based on analysis of routine load forecasting and means. It presents the way for electricity load forecasting founded on neural network(ANN),which has been tested it’s validity by example and made to be good practical effect.Fifthly, concerning the lack of concordant wave on preve nting concordant wave and non-power compensation and non-continuity on compensation, there is a topology structure of PWM main circuit and nonpower theory on active filter the waves technique and builds flat proof on the ground of Saber Designer and proves to be practical. Meanwhile, it analyzes and designs the way of non-power need of electric network tre- nds and decreasing line loss combined with DA, which have been tested its objective economic benefit throu- gh counting example.Sixthly, not only do the dissertation design a way founded on the magrginal electric price fitted to our present national electric power market with regards to future trends of electric power market in China and fair trade under the government surveillance, that is group competitio n in short-term trade under the way of grouped price and quantity harmony, but also puts forward combination arithmetic, math model of trading plan and safty economical restriction. It can solve the original contradiction between medium and long term contract price and short term competitive price with improvement on competitive percentage and cut down the unfair income difference of electric factory, at the same time, it can optimize the electric limit for all electric factories and reduce the total purchase charge of electric power from burthen curve of whole electric market network.The distribution network is an important link among the power system. Its neutral grounding mode and operation connects security and stability of the power system directly. At the same time, the problem about neutral grounding is associated with national conditions, natural environment, device fabrication and operation. For example, the activity situation of the thunder and lightning, insulating structure and the peripheral interference will influence the choice of neutral grounding mode Conversely, neutral grounding mode affects design, operation, debugs and developing. Generally in the system higher in grade in the voltage, the insulating expenses account for more sizable proportion at the total price of the equipment. It is very remarkable to bring the economic benefits by reducing the insulating level. Usually such system adopt the neutral directly grounding and adopt the autoreclosing to guarantee power supply reliability. On the contrary, the system which is lower in the voltage adopts neutral none grounding to raise power supply reliability. So it is an important subject to make use of new- type earth device to apply to the distribution network under considering the situation in such factors of various fields as power supply reliability, safety factor, over-voltage factor, the choice of relay protection, investment cost, etc.The main work of this paper is to research and choice the neutral grounding mode of the l0kV distribution network. The neutral grounding mode of the l0kV network mainly adopts none grounding, grounding by arc suppressing coil, grounding by reactance grounding and directly grounding. The best grounding mode is confirmed through the technology comparison. It can help the network run in safety and limit the earth electric arc by using auto-tracking compensate device and using the line protection with the detection of the sensitive small ground current. The paper introduces and analyzes the characteristic of all kind of grounding modesabout l0kV network at first. With the comparison with technological and economy, the conclusion is drawn that the improved arc suppressing coil grounding mode shows a very big development potential.Then, this paper researches and introduces some operation characteristics of the arc suppressing coil grounding mode of the l0kV distribution network. And then the paper put emphasis on how to extinguish the earth electric arc effectively by utilizing the resonance principle. This paper combines the development of domestic and international technology and innovative achievement, and introduces the computer earth protection and autotracking compensate device. It proves that the improved arc suppressing coil grounding mode have better operation characteristics in power supply reliability, personal security, security of equipment and interference of communication. The application of the arc suppressing coil grounding mode is also researched in this paper.Finally, the paper summarizes this topic research. As a result of the domination of the arc suppressing coil grounding mode, it should be more popularized and applied in the distribution network in the future.The way of thinking, project and conclusions in this thesis have effect on the research to choose the neutral grounding mode not only in I0kV distribution network but also in other power system..The basic function of the electric power system is to transport the electric power towards customers. The l0kV electric distribution net is a key point that connects the power supply with the electricity using on the industry, business and daily-life. For the electric power, all costumers expect to pay the lowest price for the highest reliability, but don't consider that it's self-contradictory in the co-existence of economy and reliable. To improve the reliability of the power supply network, we must increase the investment cost of the network con-struction But, if the cost that improve the reliability of the network construction, but the investment on this kind of construction would be worthless if the reducing loss is on the power-off is less than the increasing investment on improving the reliability .Thus we find out a balance point to make the most economic, between the investment and the loss by calculating the investment on power net and the loss brought from power-off. The thesis analyses on the economic and the reliable of the various line modes, according to the characteristics various line modes existed in the electric distribution net in foshan..First, the thesis introduces as the different line modes in the l0kV electric distribution net and in some foreign countries. Making it clear tow to conduct analyzing on the line mode of the electric distribution net, and telling us how important and necessary that analyses are.Second, it turns to the necessity of calculating the number of optimization subsection, elaborating how it influences on the economy and reliability. Then by building up the calculation mode of the number of optimization subsection it introduces different power supply projects on the different line modes in brief. Third, it carries on the calculation and analyses towards the reliability and economy of the different line modes of electric distribution net, describing drafts according by the calculation. Then it makes analysis and discussion on the number of optimization subsection.At last, the article make conclusion on the economy and reliability of different line modes, as well as, its application situation. Accordion to the actual circumstance, the thesis puts forward the beneficial suggestion on the programming and construction of the l0kV electric distribution net in all areas in foshan. Providing the basic theories and beneficial guideline for the programming design of the lOkV electricdistribution net and building up a solid net, reasonable layout, qualified safe and efficiently-worked electric distribution net.References[1] Wencheng Su. Factories power supply [M]. Machinery Industry Publishing House. 1999.9[2] Jiecai Liu. Factories power supply design guidance [M]. Machinery Industry Publishing House.1999.12[3] Power supply and distribution system design specifications[S].China plans Press. 1996[4] Low-voltage distribution design specifications [S].China plans Press. 1996.6Relay protection development present situationInstitution:Tianjin Electric Power Association[Abstract]reviewed our country electrical power system relay protec tion technological development process,has outlined the microcomputer re lay protection technology achievement,proposed the future relay prote ction technological development tendency will be: Computerizes, networked, protects, the control, the survey, the data comm unication integration and the artificial intellectualization.[ Key word ] relay protection present situation developme nt，relay protections future development1 relay protection development present situationThe electrical power system rapid development to the relay protection proposed unceasingly the new request, the electr onic technology, computer technology and the communication rapid development unceasingly has poured into the new vigor for the relay protection technology development, therefore, the relay protection technology is advantageous, has completed the development 4 historical stage in more than 40 years time.After the founding of the nation, our country relay prot ection discipline, the relay protection design, the relay man ufacture industry and the relay protection technical team gro ws out of nothing, has passed through the path in about 10 years which advanced countries half century passes through. The 50's, our country engineers and technicians creatively absorption, the digestion, have grasped the overseas advanced relay protection equipment performance and the movement tech nology , completed to have the deep relay protection theory attainments and the rich movement experience relay protectio n technical team, and grew the instruction function to the national relay protection technical team's establishment. The acheng relay factory introduction has digested at that time the overseas advanced relay manufacture technology, has establ ished our country relay manufacturing industry. Thus our coun try has completed the relay protection research, the design, the manufacture, the movement and the teaching complete sys tem in the 60's. This is a time which the mechanical and electrical relay protection prospers, was our country relay p rotection technology development has laid the solid foundation .From the end of the 50's, the transistor relay protectio n was starting to study. In the 60's to the 80's in arethe times which the transistor relay protection vigorous deve lopment and widely uses. Tianjin University and the Nanjing electric power automation plant cooperation research 500kv tra nsistor direction high frequency protection the transistor hig h frequency block system which develops with the Nanjing ele ctric power automation research institute is away from the p rotection, moves on the Gezhou Dam 500 kv line , finished the 500kv line protection to depend upon completely from the overseas import time.From the 70's, started based on the integration operation al amplifier integrated circuit protection to study. Has form ed the complete series to at the end of 80's integrated ci rcuit protection,substitutes for the transistor protection grad ually. The development, the production, the application the i ntegrated circuit protects which to the beginning of the 90' s still were in the dominant position, this was the integrated circuit protection ti me. The integrated electricity road work frequency conversion quantity direction develops which in this aspect Nanjing el ectric power automation research institute high frequency prot ected the vital role , the Tianjin University and the Nanji ng electric power automation plant cooperation development int egrated circuit phase voltage compensated the type direction high frequency protection also moves in multi- strip 220kv a nd on the 500kv line.Our country namely started the computer relay protection research from the end of the 70's , the institutions of hi gher learning and the scientific research courtyard instituteforerunner's function. Huazhong University of Science and Te chnology, southeast the university, the North China electric power institute, the Xian Jiaotong University, the Tianjin Un iversity, Shanghai Jiaotong University, the Chongqing Universit y and the Nanjing electric power automation research institut e one after another has all developed the different principl e, the different pattern microcomputer protective device. In 1984 the original North China electric power institute develo ped the transmission line microcomputer protective device firs t through the appraisal, and in the system the find applica tion, had opened in our country relay protection history the new page, protected the promotion for the microcomputer to pave the way. In the host equipment protection aspect, the generator which southeast the university and Huazhong Univer sity of Science and Technology develops loses magnetism prote ction, the generator protection and the generator?Bank of tra nsformers protection also one after another in 1989, in 1994 through appraisal, investment movement. The Nanjing electric power automation research institute develops microcomputer li ne protective device also in 1991 through appraisal. The Tia njin University and the Nanjing electric power automation pla nt cooperation development microcomputer phase voltage compensa ted the type direction high frequency protection, the Xian J iaotong University and the Xu Chang relay factory cooperation development positive sequence breakdown component direction h igh frequency protection also one after another in 1993, in 1996 through the appraisal. Heres, the different principle, the different type microcomputer line and the host equipmen t protect unique, provided one batch of new generation ofperformance for the electrical power system fine, the funct ion has been complete, the work reliable relay protection in stallment. Along with the microcomputer protective device rese arch, in microcomputer aspect and so on protection software, algorithm has also yielded the very many theories result. May say started our country relay protection technology from the 90's to enter the time which the microcomputer protect ed.2 relay protections future developmentThe relay protection technology future the tendency will be to computerizes, networked, the intellectualization, will p rotect, the control, the survey and the data communication i ntegration development. 2.1 computerizesAlong with the computer hardware swift and violent develo pment, the microcomputer protection hardware also unceasingly is developing. The original North China electric power instit ute develops the microcomputer line protection hardware has e xperienced 3 development phases: Ispublished from 8 lists cpu structure microcomputer prote ction, does not develop to 5 years time to the multi- cpu structure, latter developed to the main line does not leav e the module the big modular structure, the performance enha nces greatly, obtained the widespread application. Huazhong Un iversity of Science and Technology develops the microcomputer protection also is from 8 cpu, develops to take the labor controlling machine core partially as the foundation 32 mic rocomputers protection.The Nanjing electric power automation research institute f rom the very beginning has developed 16 cpu is the foundati on microcomputer line protection, obtained the big area promo tion, at present also is studying 32 protections hardware sy stem. Southeast the university develops the microcomputer host equipment protects the hardware also passed through improved and the enhancement many times. The Tianjin University from the very beginning is the development take more than 16 c pu as the foundation microcomputer line protection, in 1988 namely started to study take 32 digital signals processor (d sp) as the foundation protection, the control, the survey in tegration microcomputer installment, at present cooperated with the Zhuhai Jin automatic equipment company develops one kin d of function complete 32 big modules, a module was a mini computer. Uses 32 microcomputers chips only to focus by no means on the precision, because of the precision the a/d sw itch resolution limit, is surpassed time 16 all is accepts with difficulty in the conversion rate and the cost aspect;32 microcomputers chips have the very high integration rate more importantly, very high operating frequency and computat ion speed, very big addressing space, rich command system an d many inputs outlet. The cpu register, the data bus, the address bus all are 32, has the memory management function, the memory protection function and the duty transformation function, and (cache) and the floating number part all integ rates the high speed buffer in cpu.The electrical power system the request which protects to the microcomputer enhances unceasingly, besides protection ba sic function, but also should have the large capacity breakdown information and the data long-term storage space, the fa st data processing function, the formidable traffic capacity, with other protections, the control device and dispatches t he networking by to share the entire system data, the infor mation and the network resources ability, the higher order l anguage programming and so on. This requests the microcompute r protective device to have is equal to a pc machine funct ion. In the computer protection development initial period, o nce conceived has made the relay protection installment with a minicomputer. At that time because the small machine vol ume big, the cost high, the reliability was bad, this tenta tive plan was not realistic. Now, with the microcomputer pro tective device size similar labor controlling machine function , the speed, the storage capacity greatly has surpassed the same year small machine, therefore, made the relay protecti on with complete set labor controlling machine the opportunit y already to be mature, this will be one of development di rections which the microcomputer protected. The Tianjin Univer sity has developed the relay protection installment which Che ng Yongtong microcomputer protective device structure quite sa me not less than one kind of labor controlling machine perf orms to change artificially becomes. This kind of equipment merit includes: has the 486pc machine complete function, ca n satisfy each kind of function request which will protect to current and the future microcomputer. size and structure and present microcomputer protective device similar, the cra ft excellent, quakeproof, guards against has been hot, guards against electronmagetic interference ability, may move in th e very severe working conditions, the cost may accept. uses the std main line or the pc main line,the hardware modulation, may select the different module wilfully regarding the different protection, the disposition nimble, is easy to expand.Relay protection installment , computerizes is the irrever sible development tendency. How but to satisfies the electric al power system request well, how further enhances the relay protection the reliability, how obtains the bigger economic efficiency and the social efficiency, still must conduct sp ecifically the thorough research. 2.2 networkedThe computer network has become the information age as t he information and the data communication tool the technical prop, caused the human production and the social life appe arance has had the radical change. It profoundly is affectin g each industry domain, also has provided the powerful means of communication for each industry domain. So far, besides the differential motion protection and the vertical associat ion protection, all relay protections installment all only ca n respond the protection installment place electricity spirit. The relay protection function also only is restricted in t he excision breakdown part, reduces the accident to affect t he scope. This mainly is because lacks the powerful data co mmunication method. Overseas already had proposed the system protection concept, this in mainly referred to the safe auto matic device at that time. Because the relay protection func tion not only is restricted in the excision breakdown part and the limit accident affects the scope (this is most impo rtant task), but also must guarantee the entire system thesecurity stable movement. This requests each protection unit all to be able to share the entire system the movement and the breakdown information data, each protection unit and th e superposition brake gear in analyze these information and in the data foundation the synchronized action, guarantees th e system the security stable movement. Obviously, realizes th is kind of system protection basic condition is joins the e ntire system each main equipment protective device with the computer network, that is realization microcomputer protective device networked. This under the current engineering factor is completely possible.Regarding the general non- system protection, the realizat ion protective device computer networking also has the very big advantage. The relay protection equipment can obtain syst em failure information more, then to the breakdown nature, t he breakdown position judgment and the breakdown distance exa mination is more accurate. Passed through the very long time to the auto-adapted protection principle research, also has yielded the certain result, but must realize truly protects to the system movement way and the malfunction auto-adapted , must obtain the more systems movement and the breakdown i nformation, only then realization protection computer networked , can achieve this point.Regarding certain protective device realization computer ne tworkings, also can enhance the protection the reliability. T he Tianjin University in 1993 proposed in view of the futur e Three Gorges hydroelectric power station 500kv ultrahigh vo ltage multi- return routes generatrix one kind of distributional generatrix protection principle, developed successfully thi s kind of equipment initially. Its principle is disperses th e traditional central generatrix protection certain (with to protect generatrix to return way to be same) the generatrix protection unit, the dispersible attire is located in on v arious return routes protection screen, each protection unit joins with the computer network, each protection unit only i nputs this return route the amperage, after transforms it the digital quantity, transmits through the comput er network for other all return routes protection unit, each protection unit acts according to this return route the am perage and other all return routes amperage which obtains fr om the computer network, carries on the generatrix differenti al motion protection the computation, if the computed result proof is the generatrix interior breakdown then only jumps the book size return route circuit breaker, Breakdown gener atrix isolation. When generatrix area breakdown, each protecti on unit all calculates for exterior breakdown does not act. This kind the distributional generatrix protection principle which realizes with the computer network, has the high rel iability compared to the traditional central generatrix protec tion principle. Because if a protection unit receives the di sturbance or the miscalculation when moves by mistake, only can wrongly jump the book size return route, cannot create causes the generatrix entire the malignant accident which exc ises, this regarding looks like the Three Gorges power plant to have the ultrahigh voltage generatrix the system key po sition to be extremely important.By above may know, microcomputer protective device may enhance the protection performance and the reliability greatly , this is the microcomputer protection development inevitable trend. 2.3 protections, control, survey, data communication integrationsIn realization relay protection computerizing with under the condition, the protective device is in fact a high pe rformance, the multi-purpose computer, is in an entire electr ical power system computer network intelligent terminal. It m ay gain the electrical power system movement and breakdown a ny information and the data from the net, also may protect the part which obtains it any information and the data tr ansfer for the network control center or no matter what a terminal. Therefore, each microcomputer protective device not only may complete the relay protection function, moreover in does not have in the breakdown normal operation situation also to be possible to complete the survey, the control, th e data communication function, that is realization protection, control, survey, data communication integration.At present, in order to survey, the protection and the control need, outdoor transformer substation all equipment, li ke the transformer, the line and so on the secondary voltag e, the electric current all must use the control cable to direct to . Lays the massive control cable not only must m assively invest, moreover makes the secondary circuit to be extremely complex. But if the above protection, the control, the survey, the data communication integration computer inst allation, will install in outdoor transformer substation by t。

Electric Devices and SystemsAlthough transformers have no moving parts , they are essential to electromechanical energy conversion . They make it possible to increase or decrease the voltage lever that results in low costs ,and can be distributed and used safely . In addition , they can provide matching of impedances , and regulate the flow of power in a network.When we see a transformer on a utility pole all we is a cylinder with a few wires sticking out. These wires enter the transformer through bushings that provide isolation between the wires and the tank. Inside the tank these is an iron core linking coils, most probably made with copper, and insulated. The system of insulation is also associated with that of cooling the core/coil assembly. Often the insulation is paper, and the whole assembly may be immersed in insulating oil, used to both increase the dielectric strength of the paper and to transfer beat from the core-coil assembly to the outer walls of the tank to air. Figure shows the cutout of a typical distribution transformer. Few ideal versions of human constructions exist, and the transformer offers no exception. An ideal transformer is based on very simple concepts, and a large number of assumptions. This is the transformer one learns about in high school.Let us take an iron core with infinite permeability and two coils wound around it, one with N1 and the other with N2 turns, as shown in figure. Allthe magnetic flux is to remain in the iron. We assign sots at one terminal of each coil in the following fashion: if the flux in the core changes, inducing a voltage in the coils, and the dotted terminal of one coil is positive with respect its other terminal, so is the dotted terminal of the other coil. Or, the corollary to this, current into dotted terminals produces flux in the same direction,Assume that somehow a time varying flux is established in the iron. Then the flux linkages in each coil will be. Voltages will be induced in these two coil.On the other hand, currents flowing in the coils are related to the field intensity H. if currents flowing in the direction shown, i1 into the dotted terminal of coil 1, and i2 out of the dotted terminal of coil 2. we recognize that this is practically impossible, but so is the existence of an ideal transformer.Equations describe this ideal transformer, a two port network. The symbol of a network that is defined by these two equations is in the figure. An ideal transformer has an interesting characteristic. A two-port network that contains it and impedances can be replaced by an equivalent other, as discussed below. Consider the circuit in figure. Seen as a two port network. Generally a circuit on a side 1 can be transferred to side 2 by multiplying its component impedances , the voltage sources and the current sources,while keeping the topology the same. To develop the equivalent for a transformer we’ll gradually relax the assumptions that we had first imposed. First we’ll relax the assumption that the permeability of the iron is infinite. In that case equation does not revert to, but rather it becomes where is the reluctance of the path around the core of the transformer and the flux on this path. To preserve the ideal transformer equations as part of our new transformer, we can split i1 to two components: one i1, will satisfy the ideal transformer equation, and the other, i1 will just balance the right hand side. The figure shows this. We can replace the current source, i1 , with something simpler if we remember that the rate of change of flux is related to the induced voltage.Since the current i1 flows through something , where the voltage across it Is proportional to its derivative, we can consider that this something could be an inductance. This idea gives rise tothe equivalent circuit in figure,. Let us now relax the assumption that all the flux has to remain in the iron as shown in figure. Let us call the flux in the iron, magnetizing flux, the flux that leaks out of the core and links only coil 1. since links only coil 1, then it should be related only to the current there, and the same should be true for the second leakage flux.Again for a given frequency, the power losses in the core increase with the voltage. These losses cannot be allowed to exceed limit, beyond which thetemperature of the hottest spot in the transformer will rise above the point that will decrease dramatically the life of the insulation. Limits therefore are put to E1 and E2, and these limits are the voltage limits of the transformer. Similarly, winding Joule losses have to be limited, resulting in limits to the currents I1 and I2. Typically a transformer is described by its rated voltages, that give both the limits and turns radio. The ratio of the rated currents is the inverse of the ratio of the voltages if we neglect the magnetizing current. Instead of the transformer rated currents, a transformer is described by its rated apparent power.Under rated conditions, maximum current and voltage, in typical transformers the magnetizing current, does not exceed 1% of the current in the transformer. Its effect therefore in the voltage drop on the leakage inductance and winding resistance is negligible.Under maximum current, total voltage drops on the winding resistances and leakage inductances do not exceed in typical transformer 6% of the rated voltage. The effect therefore of the winding current on the voltages E1 and E2 is small, and their effect on the magnetizing current can be neglected.These considerations allow us to modify the equivalent circuit in figure, to obtain the slightly inaccurate but much more useful equivalent circuits in figures.Adjustable Speed DrivesBy definition, adjustable speed drives of any type provide a means of variably changing speed to better match operating requirements. Such drives are available in mechanical, fluid and electrical typed.The most common mechanical versions use combinations of belts and sheaves, or chains and sprockets, to adjust speed in set, selectable ratios-2:1,4:1,8:1 and so forth. Traction drives, a more sophisticated mechanical control scheme, allow incremental speed adjustments. Here, output speed is varied by changing the contact points between metallic disks, or between balls and cones. Adjustable speed fluid drives provide smooth, stepless adjustable speed control. There are three major types. Hydrostatic drives use electric motors or internal combustion engines as prime movers in combination with hydraulic pumps, which in turn drive hydraulic motors. Hydrokinetic and hydroviscous drives directly couple input and output shafts. Hydrokinetic versions adjust speed by varying the amount of fluid in a vortex that serves as the input-to-output coupler. Hydroviscous drives, also called oil shear drives, adjust speed by controlling oil-film thickness, and therefore slippage, between rotating metallic disk. An eddy current drive, while technically an electrical drive, nevertheless functions much like a hydrokinetic or hydrovidcous fluid drive in that it serves as a coupler between a prime mover and driven load. In an eddycurrent drive, the coupling consists of a primary magnetic field and secondary fields created by induced eddy currents. They amount of magnetic slippage allowed among the fields controls the driving speed.In most industrial applications, mechanical, fluid or eddy current drives are paired with constant-speed electric motors. On the other hand, solid state electrical drives, create adjustable speed motors, allowing speeds from zero RPM to beyond the motor’s base speed. Controlling the speed of the motor has several benefits, including increased energy efficiency by eliminating energy losses in mechanical speed changing devices. In addition, by reducing, or often eliminating, the need for wear-prone mechanical components, electrical drives foster increased overall system reliability, as well as lower maintenance costs. For these and other reasons, electrical drives are the fastest growing type of adjustable speed drive..There are two basic drive types related to the type of motor controlled-dc and AC. A DC direct current drive controls the speed of a DC motor by varying the armature voltage (and sometimes also the field voltage ). An alternating current drive controls the speed of an AC motor by varying the frequency and voltage supplied to the motor.Direct current drives are easy to apply and technologically straightforward, They work by rectifying AC voltage from the power line to DC voltage, then feeding adjustable voltage to a DC motor. With permanent magnet DCmotors, only the armature voltage is controlled. The more voltage supplied, the faster the armature turns. With wound-field motors, voltage must be supplied to both the armature and the field. In industry, the following three types of DC drives are most common, as shown in the figure.Drives: these are named for the silicon controlled rectifiers (also called thyristors ) used to convert AC to controlled voltage DC. Inexpensive and easy to use, these drives come in a variety of enclosures, and in unidirectional or reversing styles.Regenerative SCR Drives: Also called four quadrant drives, these allow the DC motor to provide both motoring and braking torque, Power coming back from the motor during braking is regenerated back to the power line and not lost.Pulse Width Modulated DC Drives: Abbreviated PWM and also called, generically, transistorized DC drives, these provide smoother speed control with higher efficiency and less motor heating, Unlike SCR drives, PWM types have three elements. The first converts AC to DC, the second filters and regulates the fixed DC voltage, and the third controls average voltage by creating a stream of variable width DC pulses. The filtering section and higher level of control modulation account for the PWM drive’s improved performance compared with a common SCR drive.AC drive operation begins in much the same fashion as a DC drive. Alternating line voltage is first rectified to produce DC. But because an AC motor is used, this DC voltage must be changed back, of inverted, to an adjustable-frequency alternating voltage. The drive’s inv erter section accomplishes this, In years past, this was accomplished using SCR. However, modern AC drives use a series of transistors to invert DC to adjustable-Frequency AC. An example is shown in figure.This synthesized alternating current is then fed to the AC motor at the frequency and voltage required to produce the desired motor speed. For example, a 60 Hz synthesized frequency, the same as standard line frequency in the United states, produces 100% of rated motor speed. A lower frequency produces a lower speed, and a higher frequency a higher speed. In this way, an AC drive can produce motor speeds from, approximately,15 to200% of a motor’s normally rated RPM-- by delivering frequencies of 9 HZ to 120 Hz, respectively.Today, AC drives are becoming the systems of choice in many industries,. Their use ofsimple and rugged three-phase induction motor means that AC drive systems are the most reliable and least maintenance prone of all. Plus, microprocessor advancements have enabled the creation of so-called vector drives, which provide greatly enhance response, operation down to zero speed and positioning accuracy. Vector drives, especially whencombined with feedback devices such as tachometers, encoders and resolvers in a closed-loop system, are continuing to replace DC drives in demanding applications. An Example is shown in the figure.By far the most popular AC drive today is the pulse width modulated type. Though originally developed for smaller-horsepower applications, PWM is now used in drives of hundreds or even thousands of horsepower—as well as remaining the staple technology in the vast majority of small integral and fractional horsepower ―micro‖ and ―sub-micro‖ AC drives, as shown in the figure. Pulse width modulated refers to the inverter’s ab ility to vary the output voltage to the motor by altering the width and polarity of voltage pulses, The voltage and frequency are synthesized using this stream of voltage pulses. This is accomplished through microprocessor commands to a series of power semiconductors that serve as on-off switches. Today, these switches are usually IGBTs, of isolated gate bipolar transistor. A big advantage to these devices is their fast switching speed resulting in higher pulse of carrier frequency, which minimizes motor noise.Power semiconductor devicesThe modern age of power electronics began with the introduction of thyristors in the late 1950s. Now there are several types of power devices available for high-power and high-frequency applications. The most notable power devices are gate turn-off thyristor, power darlington transistors,power mosfets, and insulated-gate bipolar transistors. Power semiconductor devices are the most important functional elements in all power conversion applications. The power devices are mainly used as switches to convert power from one form to another. They are used in motor control systems, uninterrupted power supplies, high-voltage dc transmission, power supplies, induction heating, and in many other power conversion applications. A review of the basic characteristics of these power devices is presented in this section.The thyristor, also called a silicon-controlled rectifier, is basically a four-layer three-junction pn device. It has three terminals: anode, cathode, and gate. The device is turned on by applying a short pulse across the gate and cathode. Once the device turns on, the gate loses its control to turn off the device. The turn-off is achieved by applying a reverse voltage across the anode and cathode. The thyristors symbol and its volt-ampere characteristics are shown in the figure. There are basically two classifications of thyristors: converter grade and inverter grade. The difference between a converter-grade and an inverter-grade thyristor is the low turn –off time (on the order of a few microseconds) for the latter. The converter-grade thyristors are slow type and are used in natural commutation (or phase-controlled) applications. Inverter-grade thyristors are used in forced commutation applications such as dc-dc choppers and dc-ac inverters. The inverter-grade thyristors are turned off by forcing thecurrent to zero using an external commutation circuit. This requires additional commutating components, thus resulting in additional losses in the inverter. Thyristors are highly rugged devices in terms of transient currents, di / dt, and dv/dt capability. The forward voltage drop in thyristors is about 1.5 to 2 V, and even at higher currents of the order of 100 A, it seldom exceeds 3 V. While the forward voltage determines the on-state power loss of the device at any given current, the switching power loss becomes a dominating factor affecting the device junction temperature at high operating frequencies. Because of this, themaximum switching frequencies possible using thyristors are limited in comparison with other power devices considered in this section.Thyristors have withstand capability and can be protected by fuses. The nonrepetitive surge current capability for thyristors is about 10 times their rated root mean square current. They must be protected by snubber networks for dv/dt and di/dt effects. If the specified dv/dt is exceeded, thyristors may start conducting without applying a gate pulse. In dc-to-ac conversion applications it is necessary to use an antiparalled diode of similar rating across each main thyristor. Thyristors are available up to 6000 V, 3500 A.Power mosfets are marketed by different manufacturers with differences in internal geometry and with different names such as megamos, hexfet,sipmos, and tmos. They have unique features that make them potentially attractive for switching applications. They are essentially voltage-driven rather than current-driven devices, unlike bipolar transistors.The gate of a mosfet is isolated electrically from the source by a layer of silicon oxide. The gate draws only a minute leakage current of the order of nanoamperes. Hence the gate drive circuit is simple and power loss in the gate control circuit is practically negligible. Although in steady state the gate draws virtually no current, this is not so under transient conditions. The gate-to-source and gate-to-drain capacitances have to be charged and discharged appropriately to obtain the desired switching speed, and the drive circuit must have a sufficiently to output impedance to supply the required charging and discharging currents. The circuit symbol of a power mosfet is shown in the figure.Power mosfets are majority carrier devices, and there is no minority carrier storage time. Hence they have exceptionally fast rise and fall times. They are essentially resistive devices when turned on, while bipolar transistors present a more or less constant over the normal operating range. Power dissipation in mosfets is I, and in bipolar it is Ic, and in bipolar it is Id. At low currents, therefore, a power mosfet may have a lower conduction loss than a comparable bipolar device, but at higher currents, the conduction loss will exceed that of bipolar. Also, the R increases with temperature.An important feature of a power mosfet is the absence of a secondary breakdown effect, which is present in a bipolar transistor, and as a result, it has an extremely rugged switching performance. In mosfets, R increases with temperature, and thus the current is automatically diverted away from the hot spot. The drain body junction appears as an antiparalled diode between source and drain. Thus power mosfet will not support voltage in the reverse direction. Although this in verse diode is relatively fast, it is slow by comparison with the mosfet. Recent devices have the didde recovery time as low as 100 ns. Since mosfet cannot be protected by fuses, an electronic protection technique has to be used.With the advancement in MOS technology, ruggedized MOSF are replacing the conventional MOSEFs. The need to ruggedize power MOSFETs is related to device reliability. If a MOSFET is operating within its specification range at all times, its chances for failing catastrophically are minimal. However, if its absolute maximum rating is exceeded, failure probability increases dramatically. Under actual operating conditions, a MOSFET may be subjected to transients—either externally from the power bus supplying the circuit or from the circuit itself due, for example, to inductive kicks going beyond the absolute maximum ratings. Such conditions are likely in almost every application, and in most cases are beyond a designer’s control. Rugged devices are made to be more tolerant for over-voltage transients. Ruggedness is the ability of aMOSFET to operate in an environment ofdynamic electrical stresses, without activating any of the parasitic bipolar junction transistors. The rugged device can withstand higher levels of diode recovery dv/dt and static dv/dt.译文：变压器尽管变压器没有旋转的不见，但是它在本质上还是属于几点能量交换设备。

电气专业英文作文As an electrical engineering major, I am fascinated by the way electricity powers our world. From the circuits in our phones to the power grid that keeps our cities running, electricity is everywhere and I want to understand it all.I love the hands-on aspect of electrical engineering. There's something so satisfying about designing a circuit on paper and then actually building it in the lab. It'slike bringing your ideas to life and seeing them work in the real world.One of the most challenging parts of studyingelectrical engineering is the math. It can be really tough to wrap your head around all the complex equations and calculations, but when you finally solve a difficult problem, it's incredibly rewarding.I'm also really interested in the future of electrical engineering, especially when it comes to renewable energy.I think it's so important for us to find sustainable ways to power our world, and I want to be a part of that innovation.In the end, I chose to study electrical engineering because I want to make a real impact on the world. Whether it's through designing more efficient power systems or creating new technology, I believe that electrical engineering has the potential to change the way we live for the better.。

电气工程专业英文作文英文，As an electrical engineering major, I havelearned a lot of knowledge and skills in this field. Electrical engineering is a branch of engineering thatdeals with the study of electricity, electronics, and electromagnetism. It is a broad field that covers a wide range of topics, including power generation, transmission, and distribution, as well as the design and development of electrical systems and devices.One of the most important skills I have learned as an electrical engineering major is problem-solving. Electrical engineering involves a lot of problem-solving, whether itis designing a new electrical system or troubleshooting an existing one. I have learned how to approach problems systematically, break them down into smaller, more manageable parts, and use my knowledge and skills to find solutions.Another important skill I have learned is communication.Electrical engineering is a team-oriented field, and effective communication is essential to the success of any project. I have learned how to communicate technical information clearly and concisely, both verbally and in writing, to colleagues, clients, and other stakeholders.In addition to these technical skills, I have also developed a range of soft skills, such as time management, teamwork, and leadership. These skills have helped me to work effectively in a variety of settings, from group projects in the classroom to internships and co-op experiences in the industry.Overall, my experience as an electrical engineering major has been challenging, but also rewarding. I have gained a deep understanding of the principles and practices of electrical engineering, as well as the skills and qualities needed to be successful in this field.中文，作为一名电气工程专业的学生，我在这个领域学习了很多知识和技能。

毕业设计（论文）外文文献翻译文献、资料中文题目：功率因数文献、资料英文题目：power factor文献、资料来源：文献、资料发表（出版）日期：院（部）：专业：电气班级：姓名：学号：指导教师：翻译日期： 2017.02.14POWER FACTORThe power factor of an AC electric power system is defined as the ratio of the real power flowing to the load to the apparent power in the circuit, and is a dimensionless number between 0 and 1 (frequently expressed as a percentage, e.g. 0.5 pf = 50% pf). Real power is the capacity of the circuit for performing work in a particular time. Apparent power is the product of the current and voltage of the circuit. Due to energy stored in the load and returned to the source, or due to a non-linear load that distorts the wave shape of the current drawn from the source, the apparent power will be greater than the real power.In an electric power system, a load with a low power factor draws more current than a load with a high power factor for the same amount of useful power transferred. The higher currents increase the energy lost in the distribution system, and require larger wires and other equipment. Because of the costs of larger equipment and wasted energy, electrical utilities will usually charge a higher cost to industrial or commercial customers where there is a low power factor.Linear loads with low power factor (such as induction motors) can be corrected with a passive network of capacitors or inductors. Non-linear loads, such as rectifiers, distort the current drawn from the system. In such cases, active or passive power factor correction may be used to counteract the distortion and raise the power factor. The devices for correction of the power factor may be at a central substation, spread out over a distribution system, or built into power-consuming equipment.Power factor in linear circuits .Instantaneous and average power calculated from AC voltage and current with a unity power factor (φ=0, cosφ=1). Since the blue line is above the axis, all power is real power consumed by the load.Instantaneous and average power calculated from AC voltage and current with a zero power factor (φ=90, cosφ=0). The blue line shows all the power is stored temporarily in the load during the first quarter cycle and returned to the grid during the second quarter cycle, so no real power is consumed.Instantaneous and average power calculated from AC voltage and current with alagging power factor (φ=45, cosφ=0.71). The blue line shows some of the power is returned to the grid during the part of the cycle labelled φ.In a purely resistive AC circuit, voltage and current waveforms are in step (or in phase), changing polarity at the same instant in each cycle. All the power entering the loads is consumed. Where reactive loads are present, such as with capacitors or inductors, energy storage in the loads result in a time difference between the current and voltage waveforms. During each cycle of the AC voltage, extra energy, in addition to any energy consumed in the load, is temporarily stored in the load in electric or magnetic fields, and then returned to the power grid a fraction of a second later in the cycle. The "ebb and flow" of this nonproductive power increases the current in the line. Thus, a circuit with a low power factor will use higher currents to transfer a given quantity of real power than a circuit with a high power factor. A linear load does not change the shape of the waveform of the current, but may change the relative timing (phase) between voltage and current.Circuits containing purely resistive heating elements (filament lamps, strip heaters, cooking stoves, etc.) have a power factor of 1.0. Circuits containing inductive or capacitive elements (electric motors, solenoid valves, lamp ballasts, and others ) often have a power factor below 1.0.Definition and calculationAC power flow has the three components: real power (also known as active power) (P), measured in watts (W); apparent power (S), measured in volt-amperes (V A); and reactive power (Q), measured in reactive volt-amperes (var).The power factor is defined asIn the case of a perfectly sinusoidal waveform, P, Q and S can be expressed as vectors that form a vector triangle such that: If is the phase angle between the current and voltage, then the power factor is equal to the cosine of the angle, , and: Since the units are consistent, the power factor is by definition a dimensionless number between 0 and 1. When power factor is equal to 0, the energy flow is entirely reactive, and stored energy in the load returns to the source on each cycle. When the power factor is 1, all the energy supplied by the source is consumed by the load. Power factors are usually stated as "leading" or "lagging" to show the sign of the phase angle. If a purely resistive load is connected to a power supply, current and voltage will changepolarity in step, the power factor will be unity (1), and the electrical energy flows in a single direction across the network in each cycle. Inductive loads such as transformers and motors (any type of wound coil) consume reactive power with current waveform lagging the voltage. Capacitive loads such as capacitor banks or buried cable generate reactive power with current phase leading the voltage. Both types of loads will absorb energy during part of the AC cycle, which is stored in the device's magnetic or electric field, only to return this energy back to the source during the rest of the cycle. For example, to get 1 kW of real power, if the power factor is unity, 1 kV A of apparent power needs to be transferred (1 kW ÷ 1 = 1 kV A). At low values of power factor, more apparent power needs to be transferred to get the same real power. To get 1 kW of real power at 0.2 power factor, 5 kV A of apparent power needs to be transferred (1 kW ÷0.2 = 5 kV A). This apparent power must be produced and transmitted to the load in the conventional fashion, and is subject to the usual distributed losses in the production and transmission processes. Electrical loads consuming alternating current power consume both real power and reactive power. The vector sum of real and reactive power is the apparent power. The presence of reactive power causes the real power to be less than the apparent power, and so, the electric load has a power factor of less than 1.Power factor correction of linear loadsIt is often desirable to adjust the power factor of a system to near 1.0. This power factor correction (PFC) is achieved by switching in or out banks of inductors or capacitors. For example the inductive effect of motor loads may be offset by locally connected capacitors. When reactive elements supply or absorb reactive power near the load, the apparent power is reduced.Power factor correction may be applied by an electrical power transmission utility to improve the stability and efficiency of the transmission network. Correction equipment may be installed by individual electrical customers to reduce the costs charged to them by their electricity supplier. A high power factor is generally desirable in a transmission system to reduce transmission losses and improve voltage regulation at the load.Power factor correction brings the power factor of an AC power circuit closer to 1 by supplying reactive power of opposite sign, adding capacitors or inductors which act to cancel the inductive or capacitive effects of the load, respectively. For example,the inductive effect of motor loads may be offset by locally connected capacitors. If a load had a capacitive value, inductors (also known as reactors in this context) are connected to correct the power factor. In the electricity industry, inductors are said to consume reactive power and capacitors are said to supply it, even though the reactive power is actually just moving back and forth on each AC cycle.The reactive elements can create voltage fluctuations and harmonic noise when switched on or off. They will supply or sink reactive power regardless of whether there is a corresponding load operating nearby, increasing the system's no-load losses. In a worst case, reactive elements can interact with the system and with each other to create resonant conditions, resulting in system instability and severe overvoltage fluctuations. As such, reactive elements cannot simply be applied at will, and power factor correction is normally subject to engineering analysis.An automatic power factor correction unit is used to improve power factor. A power factor correction unit usually consists of a number of capacitors that are switched by means of contactors. These contactors are controlled by a regulator that measures power factor in an electrical network. To be able to measure power factor, the regulator uses a current transformer to measure the current in one phase.Depending on the load and power factor of the network, the power factor controller will switch the necessary blocks of capacitors in steps to make sure the power factor stays above a selected value (usually demanded by the energy supplier), say 0.9.Instead of using a set of switched capacitors, an unloaded synchronous motor can supply reactive power. The reactive power drawn by the synchronous motor is a function of its field excitation. This is referred to as a synchronous condenser. It is started and connected to the electrical network. It operates at a leading power factor and puts vars onto the network as required to support a system’s voltage or to maintain the system power factor at a specified level.The condenser’s installation and operation are identical to large electric motors. Its principal advantage is the ease with which the amount of correction can be adjusted; it behaves like an electrically variable capacitor. Unlike capacitors, the amount of reactive power supplied is proportional to voltage, not the square of voltage; this improves voltage stability on large networks. Synchronous condensors are often used in connection with high voltage direct current transmission projects or in large industrial plants such as steel mills.Non-sinusoidal componentsNon-linear loads change the shape of the current waveform from a sine wave to some other form. Non-linear loads create harmonic currents in addition to the original (fundamental frequency) AC current. Filters consisting of linear capacitors and inductors can prevent harmonic currents from entering the supplying system.In linear circuits having only sinusoidal currents and voltages of one frequency, the power factor arises only from the difference in phase between the current and voltage. This is "displacement power factor". The concept can be generalized to a total, distortion, or true power factor where the apparent power includes all harmonic components. This is of importance in practical power systems which contain non-linear loads such as rectifiers, some forms of electric lighting, electric arc furnaces, welding equipment, switched-mode power supplies and other devices.A typical multimeter will give incorrect results when attempting to measure the AC current drawn by a non-sinusoidal load; the instruments sense the average value of a rectified waveform. The average response is then calibrated to the effective, RMS value. An RMS sensing multimeter must be used to measure the actual RMS currents and voltages (and therefore apparent power). To measure the real power or reactive power, a wattmeter designed to work properly with non-sinusoidal currents must be used.Measuring power factorPower factor in a single-phase circuit (or balanced three-phase circuit) can be measured with the wattmeter-ammeter-voltmeter method, where the power in watts is divided by the product of measured voltage and current. The power factor of a balanced polyphase circuit is the same as that of any phase. The power factor of an unbalanced polyphase circuit is not uniquely defined.A direct reading power factor meter can be made with a moving coil meter of the electrodynamic type, carrying two perpendicular coils on the moving part of the instrument. The field of the instrument is energized by the circuit current flow. The two moving coils, A and B, are connected in parallel with the circuit load. One coil, A, will be connected through a resistor and the second coil, B, through an inductor, so that the current in coilB is delayed with respect to current in A. At unity power factor, the current in A is in phase with the circuit current, and coil A provides maximum。

电气专业的英语作文In the realm of electrical engineering, English has emerged as a pivotal language for global communication and collaboration. This essay will delve into the significance of English proficiency in the field and the advantages it brings to electrical engineers.Firstly, English is the lingua franca of science and technology. The majority of technical literature, research papers, and academic journals are published in English. Being proficient in English enables electrical engineers to access a wealth of knowledge and stay updated with the latest advancements in their field. It allows for a deeper understanding of complex theories and methodologies that are often first articulated in English.Secondly, the global nature of the electrical engineering industry necessitates communication with international colleagues and partners. English serves as the common ground for professionals from diverse linguistic backgrounds. It facilitates smoother project collaborations, technical discussions, and the exchange of innovative ideas across borders.Moreover, English is the primary language used in many international conferences and seminars. Engineers who are comfortable with English can actively participate in these events, present their research, and engage in fruitfuldialogues with peers from around the world.Furthermore, the ability to communicate effectively in English is often a prerequisite for engineers seeking to work in multinational corporations or to pursue higher educationin foreign institutions. It opens up a plethora of opportunities for career advancement and personal growth.Lastly, the digital age has made English even more integral to the field. Online forums, technical blogs, and social media platforms are predominantly in English. These platforms are invaluable for troubleshooting, learning from others' experiences, and staying connected with the global electrical engineering community.In conclusion, English is not just a language but a tool that empowers electrical engineers to excel in their profession.It is a bridge that connects the global community of engineers, fostering innovation and progress in the field. Therefore, it is imperative for aspiring electrical engineers to invest time and effort in honing their English skills to fully realize their potential in this dynamic and interconnected world.。

Page1 Generators and MotorsFrom reference 11. Direct-current generators impress on the line a direct or continuous emf, one that is always in the same direction. Commercial dc generators have commutators, which distinguish them from ac generators. The function of a commutator and the elementary ideas of generation of emf and commutation are discussed in Div. 1. Additional information about commutation as applied to dc motors, which in general is true for dc generators, is given below.2. Excitation of generator fields. To generate an emf, conductors must cut a magnetic field which in commercial machines must be relatively strong. A permanent magnet can be used for producing such a field in a generator of small output, such as a telephone magneto or the magneto of an insulation tester, but in generators for light and power the field is produced by electromagnets, which may be excited by the machine itself or be separately excited from anothersource.Self-excited machines may be of the series, shunt, or compound type, depending upon the manner of connecting the field winding to the armature. In the series type of machine,the field winding (the winding which produces the magnetic field) is connected in series with the armature winding. In the shunt type, the field winding is connected in parallel,shunt, with the armature winding. Compound machines have two field windings on each pole. One of these windings is connected in series with the armature winding, and the other is connected in parallel or shunt with the armature winding.3. Armature winding of dc machines may be of the lap or the wave type. The difference in the two types is in the manner of connecting the armature coils to the commutator.A coil is the portion of the armature winding between successive connections to the commutator.In the lap type of winding (see Fig. 7.1) the two ends of a coil are connected to adjacent commutator segments. In the wave type of winding (see Fig. 7.2) the two ends of a coil are connected to commutator segments that are displaced from each other by approximately 360 electrical degrees.The typeof armature winding employed affects the voltage and current capacity of the machine but has no effect upon the power capacity. This is due to the fact that the number of parallel paths between armature terminals is affected by the type of winding. For a wavewound machine there are always two paths in parallel in the armature winding between armature terminals. For a lap-wound machine there are as many parallel paths in the armature winding as there are pairs of poles on the machine. For the same number and size of armature conductors, a machine when wave-connected would generate a voltage that would equal the voltage generated when lap-connected times the number of pairs of poles.But the current capacity would be decreased in the same proportion that the voltage was increased. The current capacity of a machine when wave-connected is therefore equal to the capacity when lap-connected divided by the number of pairs of poles.4. The value of the voltage generated by a dc machine depends upon the armature winding, the speed, and the field current. For a given machine, therefore, the voltage generated can be controlled by adjusting either the speed or the field current. Since generators are usually operated at a constant speed, the voltage must be controlled by adjusting the field current.5. Separately excited dc generators are used for electroplating and for other electrolytic work for which the polarity of a machine must not be reversed.Self-excited machines may change their polarities. The essential diagrams are shown in Fig. 7.3. The fields can be excited from any dc constant-potential source, such as a storage battery, or from a rectifier connected to an ac supply.The field magnets can be wound for any voltage because they have no electric connection with the armature. With a constant field excitation, the voltage will drop slightly fromno load to full load because of armature drop and armature reaction.Separate excitation is advantageous when the voltage generated by the machine is not suitable for field excitation. This is true for especially low- or high-voltage machines.6. Series-wound generators have their armature winding, field coils, and external circuit connected in series with each other so that the same current flows through all parts of the circuit (see Fig.7.4). If a series generator is operated at noload (external circuit open), there will be no current through the field coils, and the only magnetic flux presentin the machine will be that due to the residual magnetism which has been retained by the poles from previous operation. Therefore, the no-load voltage of a series generator will be only a few volts produced by cutting the residual flux. If the external circuit is closed and the current increased, the voltage will increase with the increase in current until the magnetic circuit becomes saturated. With any further increases of load the voltage will decrease. Series generators have been used sometimes in street-railway service. They have been connected in series with long trolley feeders supplying sections of the system distant from the supply point in order to boost the voltage. However, power rectifiers have replaced dc generators for most installations of this type.Keywords: generatorFrom reference 2Since triphased asynchronous generators are mainly used in conversion systems of a eolian energy into electric energy, their functional stability represent isof great importance. As a first step, the factors that radically affect the functional stability of these generators have been established. Thus, it was decelat the powerful influence of the capacitor bank – that provides the necessary reactive power for themagnetization of the ferromagnetic core – over the functional stability of the triphased asynchronous generator with short circuit rotor. The functional stability is greatly influenced by the charge character (type) as well. The experimental work emphasized – through the functional features – the way these parameters influence the stability area of the asynchronous generators. As far as triphased asynchronous generators with coiled rotor are concerned, the controllable blind power was analyzed the analogy being made with the situation of the necessary controllable generating capacity for of the triphased asynchronous generator with short circuit rotor.Keywords : triphased asynchronous generator.[1] D.M. Eggleston, F.S. Stoddard – Wind turbine engineering design, Van Nostrand Reinhold Company New York 1986;[2] V. I lie, L. Almaşi, şa – Utilizarea energiei vântului, Ed. Tehnică, Bucureşti, 1984;[3] Kovacs Pal –Analiza regimurilor tranzitorii ale maşinilor electrice, Ed. Tehnică, Bucureşti 1980 ;[4] R.J. Harrington, F.M.M. Bassiouny – New Approach to Determinate the Critical Capacitance for Self - Excited Induction Generators, IEEE Trans. On Energy Conversion, vol. 13, no.3, sept. 1998, pp.244 - 250;[5] Colliez, C., Tounzi, A., Piriou, F. – Vector Control of a Autonomous Induction Generator connected to a PWMRectifier. EPE `97, Trondheim, Norvegia, vol. 2, pp. 711-716;[6] Alan, I., Lipo, A. T. – Control of a Polyphase Induction-Generator/ Induction- Motor Power Conversion System Completely Isolated from the Utility. IEEE Trans. On Ind. App., vol.30, no.3, may/june 1994, pp. 636-647[7] Florin Iov – Stadiul actual în conversia energiei eoliene (Referat nr.1 – în cadrul pregătirii tezei de doctorat) martie 1998;[8] Florin Iov –Studiul ansamblului turbină eoliană – generator asincron autoexcitat (Referat nr.2 – în cad rul pregătirii tezei de doctorat) iunie 1999;Page2 Electrical Energy TransmissionFrom reference 1Growing populations and industrializing countries create huge needs for electrical energy. Unfortunately, electricity is not always used in the same place that it is produced, meaning long-distance transmission lines and distribution systems are necessary. But transmitting electricity over distance and via networks involves energy loss.So, with growing demand comes the need to minimize this loss to achieve two main goals: reduce resource consumption while delivering more power to users. Reducing consumption can be done in at least two ways: deliver electrical energymore efficiently and change consumer habits.Transmission and distribution of electrical energy require cables and power transformers, which create three types of energy loss:the Joule effect, where energy is lost as heat in the conductor (a copper wire, for example);magnetic losses, where energy dissipates into a magnetic field;the dielectric effect, where energy is absorbed in the insulating material.The Joule effect in transmission cables accounts for losses of about 2.5 % while the losses in transformers range between 1 % and 2 % (depending on the type and ratings of the transformer). So, saving just 1 % on the electrical energy produced by a power plant of 1 000 megawatts means transmitting 10 MW more to consumers, which is far from negligible: with the same energy we can supply 1 000 - 2 000 more homes.Changing consumer habits involves awareness-raising programmers, often undertaken by governments or activist groups. Simple things, such as turning off lights in unoccupied rooms, or switching off the television at night (not just putting it into standby mode), or setting tasks such as laundry for non-peak hours are but a few examples among the myriad of possibilities.On the energy production side, building more efficient transmission and distribution systems is another way to go about it. High efficiency transformers, superconducting transformers and high temperature superconductors are new technologies which promise much in terms of electrical energy efficiency and at the same time, new techniques are being studied. These include direct current and ultra high voltage transmission in both alternating current and direct current modes.Keywords: electrical energy transmissionFrom reference 2Disturbing loads like arc furnaces and thyristor rectifiers draw fluctuating and harmonic currents from the utility grid. These non sinusoidal currents cause a voltage drop across the finite internal grid impedance, and the voltage waveform in the vicinity becomes distorted. Hence, the normal operation of sensitive consumersis jeopardized.Active filters are a means to improve the power quality in distribution networks. In order to reduce the injection of non sinusoidal load currents shunt active filters are connnected in parallel to disturbing loads (Fig. 1). The active filter investigated in this project consists of a PWM controlled three-level VSI with a DC link capacitor.The VSI is connected to the point of common coupling via a transformer. The configuration is identical with an advanced static var compensator.The purpose of the active filter is to compensate transient and harmonic components of the load current so that only fundamental frequency components remain in the grid current. Additionally, the active filter may provide the reactive power consumed by the load. The control principle for the active filter is rather straightforward: The load current ismeasured, the fundamental active component is removed from the measurement, and the result is used as the reference for the VSI output current.In the low voltage grid, active filters may use inverters based on IGBTs with switching frequencies of 10 kHz or more. The harmonics produced by those inverters are easily suppressed with small passive filters. The VSI can be regarded nearly as an ideally controllable voltage source. Inmedium voltage applications with power ratings of several MVA, however, the switching frequency of today’s VSIs is limited to some hundred Hertz. Modern high power IGCTs can operate at around 1 kHz. Therefore, large passive filters are needed in order to remove the current ripple generated by the VSI. Furthermore, in fast control schemes the VSI no longer represents an ideal voltage source because the PWM modulator produces a considerable dead-time.In this project a fast dead-beat algorithm for PWM operated VSIs is developed [1].This algorithm improves the load current tracking performance and the stability of the active filter. Normally, for a harmonics free current measurement the VSI currentwould be sampled synchronously with the tips of the triangular carriers. Here, the current acquisition is shifted in order to minimize the delays in the control loop. The harmonics now included in themeasurement can be calculated and subtracted fromthe VSI current. Thus, an instantaneous current estimation free of harmonics is obtained.Keywords: active filtersFrom reference 3This report provides background information on electric power transmission and related policy issues. Proposals for changing federal transmission policy before the 111th Congress include S. 539, the Clean Renewable Energy and Economic Development Act, introduced on March 5, 2009; and the March 9, 2009, majority staff transmission siting draft of the Senate Energy and Natural Resources Committee. The policy issues identified and discussed in this report include: Federal Transmission Planning: several current proposals call for the federal government to sponsor and supervise large scale, on-going transmission planning programs. Issues for Congress to consider are the objectives of the planning process (e.g., a focus on supporting the development of renewable power or on a broader set of transmission goals), determining how much authority new interconnection-wide planning entities should be granted, the degree to which transmission planning needs to consider non-transmission solutions to power market needs, what resources theexecutive agencies will need to oversee the planning process, and whether the benefits for projects included in the transmission plans (e.g., a federal permitting option) will motivate developers to add unnecessary features and costs to qualify proposals for the plan.Permitting of Transmission Lines: a contentious issue is whether the federal government should assume from the states the primary role in permitting new transmission lines. Related issues include whether Congress should view management and expansion of the grid as primarily a state or national issue, whether national authority over grid reliability (which Congress established in the Energy Policy Act of 2005) can be effectively exercised without federal authority over permitting, if it is important to accelerate the construction of new transmission lines (which is one of the assumed benefits of federal permitting), and whether theexecutive agencies are equipped to take on the task of permitting transmission lines.Transmission Line Funding and Cost Allocation: the primary issues are whether the the federal government should help pay for new transmission lines, and if Congress should establish a national standard for allocating the costs of interstate transmission lines to ratepayers.Transmission Modernization and the Smart Grid: issues include the need for Congressional oversight of existing federal smart grid research, development, demonstration, and grant programs; and oversight over whether the smart grid is actually proving to be a good investment for taxpayers and ratepayers.Transmission System Reliability: it is not clear whether Congress and the executive branch have the information needed to evaluate the reliability of the transmission system. Congress may also want to review whether the power industry is striking the right balance between modernization and new construction as a means of enhancing transmission reliability, and whether the reliability standards being developed for the transmission system are appropriate for a rapidly changing power system.Keywords: electric power transmission[1] D. A. G. Pedder, A. D. Brown, and J. A. Skinner, “A contactless electricalenergy transmission system,” IEEE Trans. Ind. Electron., vol. 46, pp. 23–30, Feb. 1999.[2] A. Ghahary and B. H. Cho, “Design of transcutaneous energy transmission system using a series resonant converter,” in Proc. IEEE PESC’90, 1990, pp. 1–8.[3] E. Dahl, “Induction charging system,” U.S. Patent 3 938 018, Feb. 10, 1976.[4] N. Ishi et al., “Electric power transmitting device with inductive coupling,”U.S. Patent 5 070 293, Dec. 3, 1991.[5] P. Carosa, “Separable inductive coupler,” U.S. Patent 5 216 402, June 1, 1993.[6] K. Klontz et al., “Contactless battery charging system,” U.S. Patent 5 341 083, Aug. 23, 1994.[7] I. Shirai et al., “Induction charging apparatus,” U.S. Patent 5 550 452, Aug. 27, 1996.[8] J. Bolger and L. Ng, “Inductive power coupling with constant voltage output,” U.S.Patent 4 800 328, Jan. 24, 1989.[9] C. G. Kim, D. H. Seo, J. S. You, J. H. Park, and B. H. Cho, “Design of a contactless battery charger for cellular phone,” in Proc. IEEE APEC, 2000, pp. 769–773.[10] Y. Kanai, M. Mino, T. Sakai, and T. Yachi, “A noncontact power-supply card powered by solar cells for mobile communications,” in Proc. IEEE APEC, 2000, pp. 1157–1162.Page3 Requirements of an Electric Supply SystemFrom reference1Connections to external 330 kV power grids are provided using an open 330 kV switchyard. The plant is connected to the Lithuanian power grid using two transmission lines L-454 and L-453, 330 kV each, to the Belorussian power grid using three transmission lines L-450, L-452 and L-705, and to the Latvian power grid using one transmission line L-451.Connections to external power grids at 110 kV are provided using the first section of the open 110 kV switchyard. The plant is connected to the Lithuanian power grid using one transmission line “Zarasai” 110 kV, and to the Latvian power grid using one transmission line L-632.Connections between the open switchyards at 330 kV and 110 kV are established using two coupling autotransformers AT-1 and AT-2, types ATDCTN- 200000/330. Power of each autotransformer is equal to 200 MV×A. The autotransformers have a device for voltage regulation under load. The device type is RNOA-110/1000. 15 positions are provided to regulate voltage in a range (115 ± 6) kV.The open 330 kV switchyard is designed using "4/3" principle (four circuit breakers per three connections) and consists of two sections. Circuit breakers are placed in two rows. The first section of the open switchyard 110 kV is designed using “Double system of buses with bypass” structure. The second section of open switchyard 110 kV is connected to the first section through two circuit breakers C101 and C102. The second section has the same design as the first one. The followingtransmission lines are connected to the second section: L-Vidzy, L-Opsa, L-Statyba, LDuk Ötas. These transmission lines are intended for district power supplies, so they are not essential for electric power supply for the plant in-house operation.Air circuit breakers of VNV-330/3150A type are used in the open 330 kV switchyard. Air circuit breakers of VVBK-110B-50/3150U1 type are used in open switchyard 110 kV. To supply power loads on voltage level 330 kV and 110 kV, aerial transmission lines are used. Electrical connections of external grids 110 and 330 kV are presented in Fig. 8.1.Keywords: transmission linesFrom reference 2AbstractThis paper addresses sustainability criteria and the associated indicators allowingoperationalization of the sustainability concept in the context of electricity supply. The criteria and indicators cover economic, environmental and social aspects. Some selected results from environmental analysis, risk assessment and economic studies are shown. These studies are supported by the extensive databases developed in this work. The applications of multi-criteria analysis demonstrate the use of a framework that allows decision-makers to simultaneously address the often conflictingsocio-economic and ecological criteria. “EnergyGame”, the communication-oriented software recently developed by the Paul Scherrer Institute (PSI), provides the opportunity to integrate the central knowledge-based results with subjective value judgments. In this way a sensitivity map of technology choices can be constructed in an interactive manner. Accommodation of a range of perspectives expressed in the energy debate, including the concept of sustainable development, may lead to different internal rankings of the options but some patterns appear to be relatively robust.IntroductionThe public, opinion leaders and decision-makers ask for clear answers on issues concerning the energy sector and electricity generation in particular. Is it feasible tophase out nuclear power in countries extensively relying on nuclear electricity supply and simultaneously reduce greenhouse gas emissions? What are the environmental and economic implications of enhanced uses of cogeneration systems, renewable sources and heat pumps? How do the various energy carriers compare with respect to accident risks? How would internalization of external costs affect the relative competitiveness of the various means of electricity production? What can we expect from the prospective technological advancements during the next two or three decades? Which systems or energy mixes come closest to the ideal of being cheap, environmentally clean, reliable and at the same time exhibit low accident risks?How can we evaluate and rank the current and future energy supply options with respect to their performance on specific sustainability criteria?The Swiss GaBE Project on “Comprehensive Assessment of Energy Systems” provides answers to many issues in the Swiss and international energy arena. A systematic, multidisciplinary, bottom-up methodology for the assessment of energy systems, has been established and implemented. It covers environmental analysis, risk assessment and economic studies, which are supported by the extensive databases developed in this work. One of the analysis products are aggregated indicators associated with the various sustainability criteria, thus allowing a practical operationalization of the sustainability concept. Apart from technical and economic aspects an integrated approach needs to consider also social preferences, which may be done in the framework of multi-criteria analysis.Keywords: criteria indicatorsFrom reference 3Mobility of persons and goods is an essential component of the competitiveness of European industry and services as well as an essential citizen right. The goal of the EU's sustainable transport policy is to ensure that our transport systems meet society's economic, social and environmental needs.The transport sector is responsible for about 30% of the total final energy consumption and for about 25% of the total CO2 emissions. In particular thecontribution of road transport is very high (around 80% and 70% respectively). These simple data shed light on the necessity to move towards a more sustainable transportation system, but also suggest that a technological/systemic revolution in the field will positively impact the overall world’s sustainable development.From a technological point of view, a lower dependency from not renewable energy sources (i.e. fuel oil) of the road transport is the main anticipated change. In particular electric engines possibly represent the natural vehicle evolution in this direction. Indeed they have much higher energy efficiency (around three times that of internal combustion engines, ICE) and do not produce any kind of tailpipe emissions. How the electricity will be supplied to the vehicles is still unpredictable due to the too many existing uncertainties on the future development, but the electrification of the drive train will contribute to having alternative energy paths to reduce the nearly total dependency on crude oil. In particular, vehicle range and performances allowed by the different possibilities will play a key role on the debate.At the moment a great attention is attracted by electric vehicles, both hybrid and not, that will allow users to recharge their vehicles directly at home. This kind of vehicle can represent a real future alternative to the ICE vehicles in particular for what concerns the daily commuting trips (whose range is quite low). It is therefore important to understand what might be the impact on the electric supply system capabilities of this recharging activity.In this light the present study carries out an analysis of this impact for the Province of Milan (of particular relevant due the very high daily commuting trips) at a 2030 time horizon. Key issue of the analysis is the estimation of a potential market share evolution for the electric vehicles. The results obtained show that even with a very high future market penetration the impact of the vehicles on the annual energy consumption will be quite negligible. On the contrary they also show that without an appropriate regulation (e.g. the intelligent integration of electric vehicles into the existing power grid as decentralised and flexible energy storage), they could heavily impact on the daily electric power requirements.Keywords: electric vehicles[1] Frischknecht, R. et al.: Ökoinventare für Energiesysteme Grundlagen für den ökologischen Vergleich von Energiesystemen und den Einbezug von Energiesystemen in Ökobilanzen für die Schweiz. 3rd Edition. ETHZ/PSI, Zürich, 1996.[2] Dones, R. Gantner, U., Hirschberg S., Doka G., Knoepfel I.: Environmental Inventories for Future Electricity Supply Systems for Switzerland. PSI ReportNo. 96-07, Würenlingen and Villigen, February 1996.[3] Andreani-Aksoyoglu, S., Keller, J.: Short-term Impacts of Air Pollutants in Switzerland: Model Evaluations and Preliminary Scenario Calculations for Selected Swiss Energy Systems. In Brebbia C.A., Ratto C.F., and Power H. (Eds.), Air Pollution VI, Computational Mechanics Publications (1998) 799-808.[4] Institut für Energiewirtschaft und Rationalle Energieanwendung: EcoSense 2.0 U ser’s Manual. Stuttgart University, 1997.[5] Hirschberg, S., Spiekerman, G., Dones, R.: Severe Accidents in the Energy Sector. PSI Report No. 98-16, Würenlingen and Villigen, November 1998.[6] Kypreos, S.: Assessment of CO2 Reduction Policies for Switzerland, in Knowledge Infrastructures and Decision Support Systems for Integrated Modelling in Energy Management and Policies. Int. Journal of Global Energy Issues, 12 Nos.1-6 (1999) 233-243.[7] Hirschberg, S., Jakob, M.: Cost Structure of the Swiss Electricity Generation under Consideration of External Costs. SAEE Seminar “Strompreise zwischen Markt und Kosten: Führt der freie Strommarkt zum Kostenwarheit?” Bern, 11 June 1999. [8] Dones, R., Hirschberg, S., Vamanu, D.: Decision Support Tool for Sensitivity Mapping of Electricity Supply Systems Choices for Switzerland: Specification of the Concept and Software for the Interactive “EnergyGame”. Installed at PSI Forum, PSI Internal Document, Würenlingen and Villigen, 1999.[9] Gantner, U., Jacob, M., Hirschberg, S.: Grundlagen sowie ökologische undökonomische Vergleiche von zukünftigen Energieversorgungsoptionen: Methoden und Analysen. PSI Report, to be published 1999.[10] Hirschberg S. (Ed.), Energie-Spiegel: Facts für die Energiepolitik von Morgen. Nr. 1, PSI/ETHZ, Würenlingen and Villigen, 1999.[11] Krewitt, W., Hurley, F., Trukenmüller, A., Friedrich, R.: Health Risks of Energy Systems. Int. Journal of Risk Analysis, 18, No.4, 1998.[12] Hirschberg, S., Dones, R.: Health and Environmental Risk Assessment of Energy Systems in Support of Decision-Making. In Mosleh A. and Bari R.A. (Eds.), Probabilistic Safety Assessment and Management - PSAM 4, Vol. 3, Springer, London (1998) 1629- 1634.[13] Sterling, A.: Multi-criteria Mapping. Mitigating the Problems of Environmental Valuation? In J. Foster (Ed.) Valuing Nature? Ethics, Economics and the Environment, Routledge, London and New York (1997) 186-210.。

有关电气专业的英语作文I have always been fascinated by electricity and how it powers the world around us. The ability to manipulate and control the flow of electrons is truly amazing.When I first started studying electrical engineering, I was overwhelmed by the amount of knowledge and information I needed to absorb. However, as I delved deeper into the subject, I found myself becoming more and more passionate about it.One of the most exciting things about electrical engineering is the endless possibilities it offers. From designing circuits to working on power systems, there is always something new and challenging to explore.I love the hands-on aspect of electrical engineering. There is something incredibly satisfying about building and testing circuits, and seeing the results of your work come to life.The field of electrical engineering is constantly evolving, and it is crucial to stay updated with the latest technologies and advancements. This constant learning and adaptation keep the profession exciting and dynamic.The problem-solving aspect of electrical engineering is what drew me to the field in the first place. I enjoy the challenge of identifying and solving complex electrical issues, and the sense of accomplishment that comes with finding a solution.The impact of electrical engineering on the world is undeniable. From powering homes and businesses to driving technological innovations, electrical engineers play a crucial role in shaping the modern world.In conclusion, electrical engineering is a diverse and dynamic field that offers endless opportunities for learning and growth. I am excited to continue my journey in this field and see where it takes me.。

关于电气工程专业英语的作文Diving into the realm of electrical engineering is like exploring a vast, intricate web of innovation and technology that powers our modern world. This field, with its heart set on the pulse of progress, is not just about circuits and currents; it's a language of its own, with English at its core, bridging the gap between theory and application.Electrical engineering is a discipline that has evolved dramatically over the decades, and its language has kept pace, incorporating a rich lexicon of terms that describeeverything from the most fundamental components to the most cutting-edge technologies. For students and professionals alike, mastering the English terminology is crucial for understanding the principles that underpin electrical systems, from the microchip to the power grid.In this dynamic field, the ability to communicate effectively in English is paramount. Whether it's discussing the intricacies of a power electronics converter or thedesign of a high-voltage transmission line, precision in language is as important as precision in engineering. English serves as the universal medium for scholarly articles, technical specifications, and international conferences,where the latest research and developments are shared.Moreover, the language of electrical engineering is not static; it evolves with the field. New terms emerge astechnologies advance, such as "smart grid," "renewable energy," and "Internet of Things (IoT)," each reflecting the ongoing expansion of the discipline. Keeping up with these developments requires a commitment to continuous learning and an openness to embracing new concepts and terminologies.The study of electrical engineering English also extends beyond the technical. It encompasses the ability to interpret and create diagrams, to understand and apply mathematical models, and to engage in critical thinking about the implications of new technologies on society and the environment.In essence, the mastery of electrical engineering English is not just about the words; it's about the ideas they represent and the solutions they enable. It's about theability to connect with a global community of engineers, to contribute to a field that is constantly pushing the boundaries of what is possible, and to be part of a conversation that shapes the future of our world.。

电气自动化专业英语作文500字左右全文共6篇示例，供读者参考篇1Electrical Stuff is Really Cool!Hi there! My name is Timmy and I'm 8 years old. Today I want to tell you all about this super awesome thing called electrical automation. It's like magic, but with science and technology instead of wizards and wands!You see, electrical automation is all about using electricity to make machines and devices work automatically without needing people to control them directly. It's kind of like having little robot helpers that do things for you, except they're not actually robots – they're just regular machines and equipment that are really smart and can pretty much run themselves.Let me give you some examples so you can understand better. Have you ever pressed a button on a vending machine and then a drink just comes out? Or have you ever walked towards an automatic door and it just opened by itself? That's electrical automation at work! The vending machine and the automatic doors have special electrical systems and controls thatallow them to operate on their own based on things like sensing when someone puts money in or walks nearby.But that's just the start – electrical automation is used for sooo many important things! Like in factories, there are often huge machines and assembly lines that can manufacture products like cars or electronics or toys automatically with very little human involvement required. The machines are programmed to do all the work like cutting metal, putting pieces together, painting, etc. Electrical controls and computers make it all happen in a perfectly synchronized way.Electrical automation is also super important for things that help make our lives easier and more convenient. Like elevators –instead of having to pull yourself up with ropes, the elevator uses electrical motors and controls to move between floors automatically when you push a button. Or traffic lights that know when to turn green, yellow and red to control the flow of vehicles and pedestrians. Or heating and air conditioning systems that automatically adjust temperatures in buildings to keep things comfortable.And you know what's really cool? Electrical automation isn't just for big industrial things – it can be used for all kinds of neat gadgets and gizmos too! Like robot vacuums that can clean yourfloors automatically while you're at school. Or smart home systems where you can control the lights, temperature, music and more just by talking to a virtual assistant. It's like living in the future!My dad is actually an electrical engineer, which means he designs and builds a lot of the systems and equipment used for electrical automation. From what I understand, it involves using things like electrical circuits, programming, sensors, motors and other components in really clever ways to create automated control systems. It sounds pretty complicated to me, but my dad seems to really enjoy his job.I still have a lot to learn about how electrical automation really works behind the scenes, but I think it's just so amazing how it allows us to do so many tasks automatically and efficiently using the power of electricity. We can manufacture products, control environments, move things around and so much more –all with the help of smart automated systems running on electricity. Isn't that wild?Well, those are my thoughts on electrical automation for now. Maybe when I'm older and a little bit smarter, I can learn even more about this incredible technology. But for now, I'm justglad it exists to make so many awesome things possible! Electrical automation is the best!篇2The Magical World of Electrical AutomationHave you ever wondered how machines work? Things like robots, traffic lights, and even video games are powered by something called electrical automation. It's like magic, but it's real science!Electrical automation is all about using electricity to control and operate different machines and systems. It's like having a team of tiny, invisible helpers that make everything run smoothly.Imagine you're playing a video game, and your character needs to jump over a pit. When you press the jump button, an electrical signal is sent through wires to the game console. This signal tells the console to make your character jump on the screen. It happens so fast that it feels like magic!But electrical automation isn't just for games. It's used in all sorts of important places, like factories and power plants. In a factory, robots are controlled by electrical automation to buildthings like cars and toys. These robots can move quickly and precisely, following instructions from computers.Even something as simple as a traffic light uses electrical automation. When the light turns green, an electrical signal tells the cars that it's safe to go. When it turns red, another signal tells the cars to stop. This helps keep everyone safe on the roads.Electrical automation also plays a big role in keeping our homes comfortable. Your air conditioner, heater, and even your refrigerator all use electrical automation to work properly. Imagine if you had to manually turn on your fridge every time you wanted a cold drink!But how does electrical automation work? It's all thanks to a special kind of machine called a controller. Controllers are like the brains of electrical automation systems. They receive information from sensors, like buttons or switches, and then send out signals to control other parts of the system.For example, when you press the button on a remote control, a sensor sends a signal to the controller in your TV. The controller then sends a signal to the TV to change the channel or adjust the volume.Electrical automation is like having a team of helpers that can do things faster and more accurately than humans. It makes our lives easier and helps keep us safe. And who knows, maybe one day you'll become an expert in electrical automation and create your own magical machines!篇3Electrical Automation is Super Cool!Hi there! My name is Tommy and I'm 8 years old. I go to Oakwood Elementary School and I'm in third grade. Today I want to tell you all about this really cool thing called electrical automation. It's a major you can study in university and it's all about using electricity to control machines and systems. How awesome is that?So what exactly is electrical automation? Well, it's kind of like telling robots what to do using electrical signals and computer programs. These robots could be big industrial machines in a factory or even the electronics in our houses and cars. Basically, anything that uses electricity can likely be automated.The people who study electrical automation, called electrical automation engineers, spend a lot of time programming and writing code篇4My Big Dream JobHi, my name is Tommy and I'm 8 years old. I love building things with Legos and K'nex and putting together models and machines. My favorite subject in school is science because I get to learn about how things work. My dream is to become an electrical automation engineer when I grow up!What is an Electrical Automation Engineer?An electrical automation engineer is someone who designs and builds the control systems that operate big machines and factories. They use computers to program and automate things like robots, assembly lines, power plants, and more. It's a really high-tech and important job!Electrical automation engineers need to know a lot about electricity and electronics. They have to understand how circuits work and how to control electrical components like motors, sensors, and switches. But they also need strong computer programming skills to write the code that tells the machines what to do.On a typical day, an automation engineer might design the electrical wiring plans for a new factory robot. They would plan out where all the motors, sensors, and other components need to go and how they connect together electrically. Then they would write software code to control the timing and movements of the robot based on sensor inputs.Another day, they may analyze the performance of machines on an assembly line. They could use data and computer models to optimize the processes and improve efficiency. Or they may troubleshoot problems and update programming if a machine stops working right.The Skills You NeedTo become an electrical automation engineer, you first need a university degree, whic篇5My Daddy's Cool Job with Robots and ComputersMy daddy has a really neat job! He's an electrical engineer and works with robots and computers and all sorts of cool things.I don't really understand everything he does, but I think it's super awesome.Daddy says he works in something called "electrical automation." I'm not totally sure what that means, but I know it has to do with using electricity to make machines run by themselves without people having to control them. How wild is that?Daddy showed me his workplace once and it was like a scene from a sci-fi movie! There were these huge robot arms moving stuff around and assembling things. And there were tons of computers controlling everything. Daddy said the robots and computers can make things faster and better than humans can.Apparently, the robots get instructions from the computers on what to do and how to do it. The computers have special programs called "software" that tell the robots the right movements to make. If something gets messed up, the computers can detect it and fix it or stop the robots. It's like the computers are the brains and the robots are the muscle!I remember Daddy pointing out these things called "sensors" on the robots. These little gizmos can detect stuff like motion, heat, and even colors. The sensors send signals to the computer to let it know what's happening. Based on that information, the computer can adjust what the robots are doing.For example, if a sensor sees a red light, it might tell the robot to stop moving.Daddy also works a lot with things called PLCs - that's short for "programmable logic controllers." He programs them with code, sort of like the code in a computer or video game. The PLC then controls machines by turning motors and lights on and off. It decides what the machines should do based on the program Daddy writes and input from sensors.One of the hardest parts of Daddy's job is setting everything up just right. All the robots, computers, PLCs, sensors, and other equipment have to be installed and connected properly. There are miles of wires and cables everywhere! Even a little mistake can cause huge problems. That's why Daddy has to test and troubleshoot everything over and over.Daddy has a bunch of other duties too. He has to read diagrams and blueprints to understand how systems are designed. He programs human-machine interfaces (HMIs) so people can monitor and control the automated processes. And he's always analyzing data and looking for ways to improve efficiency, quality, and safety.I don't know about you, but this electrical automation stuff sounds unbelievably complex to me! Daddy has to be a master atcomputers, programming, electronics, robotics, and all kinds of other technical topics. I'm amazed he can keep it all straight!What I think is really cool, though, is how Daddy's work helps manufacture so many products more easily. The automation systems he designs are used to make all sorts of things like cars, electronics, food, medicine, and toys. Pretty much everything you buy was probably made with the help of robots and other automated equipment. Wild, right?I'm really proud of my daddy and the important work he does. Watching him is what first got me interested in science and technology. Who knows, maybe I'll end up doing something similar when I grow up! For now, I'll just keep asking Daddy a million questions about his fascinating job. Electrical automation is the coolest!篇6My Exciting Visit to the Electrical Automation FactoryHi friends! Last weekend, my dad took me on a super cool trip to visit an electrical automation factory. At first, I wasn't sure what that even meant, but boy was I in for an amazing surprise!When we arrived, a really nice lady named Emily greeted us. She had a bright yellow hard hat and a safety vest. Emily said she would be our tour guide for the day. She told us the factory makes all sorts of machines and robots that help run other factories and power plants. I thought that was already pretty neat!First, Emily took us into a huge room filled with big metal pieces and tools. She said this was the assembly area where all the automation equipment gets built. There were sparks flying everywhere as workers welded pieces of steel together. The loud clanging noises kind of made my ears hurt, but I still thought it looked awesome to see all the tough people working with fire and metal.Next, we went to another area where the robots were actually being put together. This room had way less noise, but it looked like a science lab with computers everywhere! Emily explained that highly skilled engineers and programmers work in this area to build the "brains" for the robots. They have to write tons of codes and instructions to make the robots smart and able to do tasks. It was mind-boggling to see how complicated it all looked.After that, we visited the testing zone, which was easily my favorite part. This is where they ran the finished robots and automation systems through trials to make sure they worked right before shipping them out. We saw robots picking up boxes, moving things around, and even building other little robot parts! The robots moved so smoothly and precisely, it was like watching a dance. Emily let me control one of the small robot arms, which was a little tricky but really fun.Towards the end of the tour, Emily brought us to a showroom area that had examples of all the amazing automation equipment the factory builds. There were little robot arms used for delicate work like electronics assembly, big heavy-duty robot cranes that can lift tons of weight, and automated conveyor systems that can move tons of parts and products around a factory. It seemed like there were machines there that could automate just about any task!On the way home, I asked my dad how the factory workers were able to build such incredible robots and automation systems. He said it took many years of education, training, and experience in fields like electrical engineering, programming, robotics, and manufacturing. He told me that if I worked reallyhard in school, especially in math, science and technology classes, maybe I could have an awesome job like that someday too!I had no idea what electrical automation really meant before the factory tour. But after seeing it in person, I think it's one of the coolest things ever! All those robots and automated machines running factories and plants is straight out of a science fiction movie. I definitely want to learn more about how it all works. Who knows, maybe I'll grow up to build amazing robots myself someday! For now, I just want to say a huge thanks to Emily and everyone at the factory for showing me their awesome automation world.。