电气专业英语论文
电气毕业论文设计英语文献原文+翻译.doc
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
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完整版
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
(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
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
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.。
电气自动化英文论文
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。
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Page1 Electrical Energy Transmission（电能输送）From 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 energy more 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 anddistribution 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.出自文献 1：人口增长和工业化国家导致电力能源的庞大需求量. 不幸的是, 电力的使用和生产常常不是在相同的地方，意味着长距离传输线路配电系统是必需的. 然而长距离输电以及通过网络这就涉及到能量损耗的问题。
.所以，随着需求的增长，就要使得这个损耗最小化，以达到两个主要目标: 在减少资源消耗，同时为用户传送更多电能。
至少有两种方式可以实现减少消耗量：更有效地传送电能以及改变用户的习惯。
电能的传输和分配需要电缆和电力变压器, 他们产生三种类型的能量损失：焦耳效应, 那些在导体发热过程中损失的能量(例如铜金属线)；电磁损耗, 这部分能量被转化为电磁场；电介质效应, 这部分能量在绝缘材料中被吸收。
传输电缆中的焦耳效应导致大约 2.5 % 的损耗，电力变压器中这个损耗大约在 1 %到 2 %之间 (取决与变压器的类型和电压等级). 所以在1000兆瓦的发电厂产出的电能中节省仅仅1%就意味着向用户传输了10 MW 能量，这是远不可忽视的：和它相同的能量，我们可以提供给1 000 - 2 000个家庭。
改变消费习惯涉及到宣传计划，这常常由政府或积极团体进行。
这仅是些简单的小事，例如关掉无人房间的灯，或在晚上关掉电视（不只是把它进入待机模式），或把洗衣服安排在非高峰时段，这仅仅是无数的可行性中的几个例子。
在能源生产方面，建立更有效的传输和分配系统是减少损耗的另一种方式。
高效变压器、超导变压器、高温超导体是能够保证电能效率的新技术，同时我们要研究新的工艺。
这包括交直流切换模式下的直流和特高压输电。
From 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 thevicinity becomes distorted. Hence, the normal operation of sensitive consumers is 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 current would 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 from theVSI current. Thus, an instantaneous current estimation free of harmonics is obtained.出自文献 2：例如电弧炉和可控硅整流器这样的配电网负载会对公用电网产生扰动和谐波电流。