电气专业毕业设计外文翻译--小区配电设计
毕业设计外文原文+翻译(电力系统)
河南理工大学HENAN POLYTECHNIC UNIVERSITY英文文献翻译En glish literature tran slati on学院：电气工程与自动化学院专业班级：___________ 电气11-4班_______ 姓名： __________________ 宋家鹏_______ 学号：311008001120 __________ 扌旨导老师：____________ 汪旭东_______2014年6月5日河南理工大学HENAN POLYTECHNIC UNIVERSITY2.5 对称三相电路在这一部分，我们介绍三相对称电路的一下几个话题：丫连接,相电压，线电压，线电流，△形连接负荷，△ - Y变换，以及等效的相图。
c Ca Ab B图2-10三相Y连接电源带Y连接对称负荷电路图对称Y连接图2-10显示的是一个三相Y连接电源带Y连接对称负荷电路图。
对于Y连接电路，每个相的中性点是连接起来的。
在图2-10中电源中性点标记的是n,而负载中性点标记的是N。
把三相电源假设为理想电源，即阻抗忽略不计。
同时，电源和负载之间线路阻抗，中性点n与N之间的线路阻抗也可忽略不计。
三相负荷是对称的，意味着三相之中任意两相间的阻抗是相同的。
对称相电压在图2-10中,三相电源的终端呗标记为a、b、c,电源相电压标记为E an ,E bn，E cn，当电源的三相电压有相同的幅度，任意两相之间互差120度角时，电源是对称的。
当以E an 作为参考相量时，相电压的幅值是10V，对称三相相电压如下所示：E an=10 0E bn10 120 10 240 (2.5.1 )E cn10 120 10 240河南理工大学HENAN POLYTECHNIC UNIVERSITY图2-11以E an 作为参考的对称正序相电压向量图当E an 超前E bn 120度，E bn 超前E cn 以120度角时，此时的相序称为正相序或 者abc 相序。
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。
毕业论文外文翻译-高层建筑供配电系统设计
毕业论文外文翻译-高层建筑供配电系统设计Design of Power Supply and Distribution System for High-rise BuildingsAbstractPower supply and distribution system is the lifeline of high-rise buildings. The design of power supply and distribution system is based on the characteristics of high-rise buildings, which requires not only reliable supply of power, but also the safety of electricity utilization and efficient energy consumption. In this paper, the design of power supply and distribution system for high-rise buildings is discussed, focusing on the selection of power supply mode, the design of power distribution system, the design of grounding system, the selection of electrical equipment and the design of lightning protection system. The application of advanced technologies such as distributed power supply, energy management and control system, and intelligent electrical equipment can improve the energy efficiency and utilization of high-rise buildings, reduce energy consumption and carbon emissions, and promote the development of green buildings.Keywords: high-rise buildings; power supply and distribution system; energy efficiency; green buildingsIntroductionHigh-rise buildings are an important symbol of urban development and represent the trend of modern architecture. With the continuous improvement of people’s living standards, the demand for high-rise buildings is increasing. Power supply and distribution system is an essential part of high-rise buildings, which plays a crucial role in the operation and maintenance of buildings. The design of power supply and distribution system for high-rise buildings needs to consider many factors, such as technical performance, safety and reliability, energy efficiency, economic benefits and environmental protection, etc. In recent years, with the rapid development of new energy and advanced technology, the design of power supply and distribution system for high-rise buildings has undergone significant changes, which focus on improving energy efficiency and reducing emissions. This paper analyzes the design of power supply and distribution system for high-rise buildings, summarizes the selection principles and design methods of various systems, and explores the application of new technologies to improve energy efficiency and promote the development of green buildings.1. Selection of Power Supply ModeThe power supply mode is the basic foundation of power supply and distribution system of high-rise buildings. In the selection of power supply mode, it is necessary to consider the characteristics of the building and the surrounding environment, and ensure the reliability and safety of power supply. Currently, the main power supply modes for high-rise buildings are grid-connected power supply and distributed power supply.1.1 Grid-connected Power SupplyGrid-connected power supply is a traditional power supply mode, which is widely used in high-rise buildings. It has the advantages of reliable power supply, convenient operation and maintenance, and stable voltage and frequency. However, grid-connected power supply is vulnerable to natural disasters such as typhoons and earthquakes, and may cause power outages, which will affect the normal life and work of residents. Moreover, the development of distribution network is limited by the capacity of the grid, which may cause overloaded operation and reduce the energy efficiency of high-rise buildings.1.2 Distributed Power SupplyDistributed power supply is a new power supply mode, which can improve the energy efficiency of high-rise buildings and reduce the dependence on the grid. Distributed power supply includes combined heat and power (CHP), solar power, wind power and other renewable energy sources. CHP is a highly efficient power generation technology, which can generate electricity and heat at the same time, and utilize the waste heat for air conditioning and domestic hot water. Solar power and wind power are clean energy sources, which have the advantages of zero emissions and long service life. Distributed power supply can reduce the transmission and distribution losses of power supply, and improve the energy efficiency of high-rise buildings. However, the initial investment of distributed power supply is relatively high, and the technical level of electrical equipment and maintenance management is demanding.2. Design of Power Distribution SystemThe power distribution system is responsible for the power transmission and distribution of high-rise buildings, which should ensure the safety and reliability of the power supply. The design of power distribution system includes the selection of power distribution equipment, the layout of power distribution room, and the calculation of power load.2.1 Selection of Power Distribution EquipmentThe selection of power distribution equipment should meet the requirements of technical performance, safety and reliability, and energy efficiency. The main power distribution equipment includes switchgear, transformer, busbar, distribution panel, etc. The switchgear should have the function of over-current protection, short-circuit protection and earth leakage protection, and should have the advantages of small volume, low noise and high reliability. The transformer should be selected according to the capacity and voltage level, and should have the advantages of low loss, high efficiency and small size. The busbar should have the advantages of high strength, good conductivity and low resistance. The distribution panel should have the functions of metering, control, protection and communication, and should be easy to operate and maintain.2.2 Layout of Power Distribution RoomThe layout of power distribution room should be reasonable and convenient for operation and maintenance. The power distribution room should be located near the power supply entrance, and should have the advantages of good ventilation, dry, clean and spacious. The power distribution room should be equipped with the necessary security measures, such as fire prevention, explosion-proof, and lightning protection.2.3 Calculation of Power LoadThe calculation of power load is the key to the design of power distribution system. The power load includes lighting load, air conditioning load, power load and special load, etc. The calculation of power load should take into account the diversity of load, the possibility of peak load, and the capacity of power supply equipment. The primary consideration is to ensure the safety and reliability of power supply, and then to improve the energy efficiency of power utilization.3. Design of Grounding SystemThe grounding system is an important safety measure for high-rise buildings. The design of grounding system should meet the requirements of electrical safety and electrostatic discharge protection.3.1 Electrical SafetyThe grounding system should have the functions of lightning protection, over-voltage protection, over-current protection and earth leakage protection, etc. The grounding resistance should be less than the specified value, and the grounding wire should have good conductivity and corrosion resistance. The grounding system should be comprehensively tested and maintained regularly.3.2 Electrostatic Discharge ProtectionThe electrostatic discharge protection is to prevent the accumulation of static electricity and the damage of electrical equipment. The design of electrostatic discharge protection includes the selection of anti-static grounding material, the setting of anti-static floor, and the installation of anti-static equipment. The electrostatic discharge protection is especially important for data centers and sensitive electrical equipment.4. Selection of Electrical EquipmentThe selection of electrical equipment is an important part of the design of power supply and distribution system for high-rise buildings. The selection of electrical equipment should meet the requirements of technical performance, safety and reliability, environmental protection and energy efficiency.4.1 Technical PerformanceThe electrical equipment should meet the relevant national and international standards, and have the characteristics of high efficiency, low noise, long service life and easy maintenance. The electrical equipment should have the functions of protection, control, measurement and communication, and should be compatible with the automation system.4.2 Safety and ReliabilityThe electrical equipment should have the functions of over-current protection, short-circuit protection, ground connection protection and lightning protection, etc. The electrical equipment should be installed and maintained by qualified personnel, and should be tested and checked regularly to ensure the safety and reliability of power supply and distribution system.4.3 Environmental Protection and Energy EfficiencyThe electrical equipment should have the advantages of environmental protection and energy efficiency, and should meet the requirements of green building standards. The electrical equipment should have the functions of power monitoring, energy management and control, and should be able to optimize the energy utilization and reduce the energy consumption.5. Design of Lightning Protection SystemThe lightning protection system is an important safety measure for high-rise buildings, which can prevent the damage of lightning to electrical equipment and human life. The design of lightning protection system includes the selection of lightning protection device, the installation of lightning rod, the connection of grounding wire, and the calculation of lightning protection zone.5.1 Selection of Lightning Protection DeviceThe lightning protection device should have the functions of lightning protection, over-voltage protection, surge protection and electromagnetic pulse protection, etc. The lightning protection device should be reliable and durable, and should meet the relevant national and international standards.5.2 Installation of Lightning RodThe lightning rod should be installed on the roof of high-rise buildings, and should be connected with the grounding system. The lightning rod should be placed in a high position, and should be made of light and strong materials, such as aluminum alloy or stainless steel. The lightning rod should be inspected regularly to ensure its effectiveness.5.3 Connection of Grounding WireThe grounding wire should be connected with the lightning rod, the grounding system, and the electrical equipment. The grounding wire should have the advantages of low resistance, good conductivity and corrosion resistance. The grounding wire should be tested and checked regularly to ensure its effectiveness.5.4 Calculation of Lightning Protection ZoneThe calculation of lightning protection zone is the basis for the design of lightning protection system. The lightning protection zone includes the direct lightning strike zone and the induced lightning zone. The direct lightning strike zone is the area covered by the lightning rod, and the induced lightning zone is the area beyond the direct lightning strike zone. The calculation of lightning protection zone should consider the characteristics of lightning, such as the stroke current, the distance from the lightning source, and the soil resistivity.ConclusionThe design of power supply and distribution system for high-rise buildings is a complex and important work. The selection of power supply mode, the design of power distribution system, the design of grounding system, the selection of electrical equipment, and the design of lightning protection system are the main aspects of the design of power supply and distribution system. The application of advanced technologies such as distributed power supply, energy management and control system, and intelligent electrical equipment can improve the energy efficiency and utilization of high-rise buildings, reduce energy consumption and carbon emissions, and promote the development of green buildings. The design of power supply and distribution system for high-rise buildings should adhere to the principles of safety, reliability, energy efficiency, economic benefits and environmental protection, and strive to create a better living and working space for residents.。
小区供配电设计_毕业设计说明书 精品
吉林化工学院毕业设计说明书小区供配电设计The Power Supply design学生学号：09580133学生姓名：专业班级：电气0901指导教师：孙浩职称：讲师起止日期：2013.3.04～2013.6.17吉林化工学院Jilin Institute of Chemical Technology吉林化工学院毕业设计说明书摘要本设主要阐述了现代化小区各系统电气设计的设计依据。
首先应该对小区的负荷进行统计，在统计的时候应全面考虑，包括近几年来当地小区的一户平均用电水平，以及逐年的变化趋势。
还与一些大城市的户平均用电水平进行了比较，以及已经建设好的小区的变压器的负荷情况来综合考虑每户应该规划的负荷，以免造成电能的浪费和投资的增多。
确定好负荷之后，确定变压器的容量。
要紧跟变压器的发展，采用性价比比较高的变压器。
考虑到居民小区本身的特点，以及箱式变压器的蓬勃发展，宜把小区分成若干供电团组来供电，由总控制室来管理。
其中总控制室配备无功补偿，并且安装一台或两台油式变压器来给附近的住宅楼供电。
在变压器的选址方面，严格遵守电力安全规定，绝对不能影响居民日常生活。
在主接线方面充分结合了小区的负荷分布情况和道路的走向，本着高效，节约的原则确定了方案。
在电缆的选择和铺设方面，严格遵照《电力工程电缆敷设规范》等相关的国家行业标准来选择和铺设。
进行了短路电流的计算，主要设备的选择和校验，及接地防雷的设计。
关键词：配电系统；变电所；变压器小区供配电设计AbstractThis is works for the end of the power system , to study.the domestic load for small residential area . Statistics Load of small residential,we must think many things. Including the electricity consumption of the local residential in recent years, and the trend of changes year by year. I also contrast with the electricity consumption of the developed city ,and the Situation of transformers that have constructed. These work is to avoid the waste of the power of electricity and the waste of investment.After the confirmition of lode, I ensure the capacity of the transformer. With the evelopment of the transformer,I choose the transformer that have a good price quality. Considering the characteristic of district and the greate development of box-type electric substation ,It is good to divide the district to several zones. Every zone’s power is supplied by a box-type electric substation. the command is equiped by parallel capacitor，and one or two transformers that offer electric power to buildings nearby. In the field of address of transformer ,I follow electricity ordinanceand electrical safety strictly.It mustn’t affect the normal life. When drawing the schematic diagram ,I consider the distribution of the domestic load and the direction of the roads , on the principle of high efficiency and save resources ,to optimize of the plan.In the respect of underground cable ,I follow the Cable Layingof electric power engineering handbook and other relating to national standards. the Short Circuit Current has been analyzed, Major equipment has beed tested and calibrated. lightning protective earthing system has been designed in a systematic way.Keywords:Power distribution system；Power substation；The transformer吉林化工学院毕业设计说明书目录摘要 (I)Abstract (II)第1章概述 (1)1.1 设计对象及目标 (1)1.2 设计的主要任务 (1)1.3 设计遵循的原则 (1)1.4 设计资料 (1)1.4.1小区平面图 (1)1.4.2供电电源情况 (2)1.5 当地的气象状况 (2)1.6 当地用电费用 (2)1.7 对于电气设计的要求 (3)第2章负荷等级及供电电源 (4)第3章无功补偿 (7)3.1 无功补偿点的设定 (7)3.2 无功补偿容量的确定 (7)第4章变压器的选择和电气主接线 (11)4.1 无功补偿后小区负荷 (11)4.2 选择变压器的原则 (11)4.3 选择变压器的数量 (12)4.4 选择变压器的容量安装一台主变压器 (12)4.5 其他因素 (12)4.6 负荷中心的计算 (12)4.7 主变压器选择的方案 (13)4.8 变电所主接线方案的选择 (13)第五章短路电流计算 (15)5.1 造成短路的原因 (15)5.2 短路造成的后果 (15)5.3 短路的几种形式 (15)5.4 短路电流的计算 (16)5.5 标幺值法计算 (16)小区供配电设计5.6 计算电路图及短路电流计算 (18)第6章变配电所一次设备的选择和校验 (22)6.1 高压一次设备的选择校验项目和条件 (22)6.2 380V侧设备选择 (26)第7章二次回路和继电保护 (31)7.1 二次回路 (31)7.2 电能测量 (31)7.3 变压器的继电保护 (32)7.4 高压断路器的控制和信号回路 (33)第8章防雷接地系统 (34)8.1 防雷措施 (34)8.2 接地及等电位 (34)8.3 防雷电波侵入 (35)8.4 本工程防雷等级 (35)结论 (36)参考文献 (37)致谢 (38)吉林化工学院毕业设计说明书第1章概述1.1 设计对象及目标某市某小区，全小区总面积约30000平方米。
电气自动化专业外文翻译配电自动化
附录二英文资料及翻译Distribution AutomationDistribution Automation Increases ReliabilityThe Long Island Lighting Co. (LILCO) provides service to over a million customers via 750 plus distribution feeders, comprised mainly, of overhead lines. These feeders are subject to the usual storm related problems involving damage due to thunderstorms, lightning, tree contact, ice storms and hurricanes. Compared with other New York state electric utilities, on average, LILCO provides the fastest restoration, although customers have in the long time the power cut disturbance.An analysis of customer outages determined that about 78% of interruptions were due to faults on main three phase lines. A fault on the main line would cause, on average, 2000 customers to lose power. In order to reduce these outages, the company has instituted reliability programmers that include trimming trees, installing lighting arresters, installing covered wire and replacing obsolete armless insulators. These programmers reduced outages, but were not sufficient to reach the desired level of service continuity. To further improve reliability, LILCO has installed an advanced distribution automation system, developed jointly by LILCO and Harris Distributed Automation Products, Calgary, Alberta, Canada. This system isolates faults and restores no damaged portions of the main tine circuit based on real time parameters of voltage, current, breaker, status and supervisor controlled switch positions. Since this project was initiated in 1993.After setting up the malfunction detection system, the Harrison company developed one kind to be called “SMART” (keen) the switch or automatic circuit breaker's advanced RTU system, this kind of sophisticated equipment's use did not need the communication network or the relay coordination, met the automatic circuit breaker on 400 existing switches. This duty was completes officially in April, 1996. Moreover LIL Corporation also installs has 350 to have automatic turn off performance S&C the SCADA switch. These 750 breakdown automatic turn off switch caused LIL Corporation to reduce the power cut influence which 25% user acceptor three phase breakdown created again. Altogether had 240,000 users in is half in the time exempts has continued the power failure the disturbance.The second stage is project as foundation Harrison SCADA the system and sets up the breakdown automatic turn off switch communication installment including the assembly take PC. They may cause the operator to implement the distant surveillance and the control to the switch. Harrison PC the SCADA system take the three phase electricity as a foundation, provides the voltage, the electric current, the power factor, the load contour as well as other real time values, achieves by the time displays this electrical power distribution system's superiorityfully. In has carried on an appraisal after some communication method .LIL Corporation has selected the microwave data system wide frequency communication network. This kind of microwave data system also mixed in the free frequency band wide frequency to jump quite the technology. As a result of the use microwave data system, LIL Corporation has installed 750 Blowers; the communication coverage reaches 90% in several months.The third stage's mission requirement produces one kind of self recovery to the trouble free supply line's advanced system. Elaborates the self recovery system to involve to Harrison D-200, it takes the front end processor to use in with RTUS maintains communication contacting.Harrison D-200 obtains the information from the automatic turn off switch place; it supplies the power failure information. Moreover, Harrison D-200 also gains the transformer substation circuit breaker situation and is affected line's load as well as the neighbor line information. Afterward. According to the real time voltage, the load, the circuit breaker situation, the switch position and the security block system situation, this system after the computation, reported resumes the power supply the correct plan. Designs this kind of self recovery system to be able simultaneously to restore 12 supply lines, but may also support reaches seven attires on the split ring line's switch. In addition, the operator can for each return route establishment automation rank. These ranks include.Manual pattern: PC the SCADA system does not send out restores the power supply instruction, the operators may play the comprehensive monitoring and the prompt role to the switch. Operator instruction pattern: Harrison the D-200 definite fault coverage, then the basis real time information presents a simulation screen for PC SCADA as well as must resume power supply the sequence of operation. If the operators agree with the system instruction, the operator issues the instruction, causes PCSCADA to carry out the essential sequence of operation. Any starts link's malfunction, can hinder resumes the power supply, thus enables the line to change over to the manual pattern.Completely automatic pattern: The establishment fault coverage, subsequently automatically carries out starts, restores to the trouble free line's power supply. All automatic links are determined according to the real time information data. Therefore, the operator work process (interconnection) prevents the staff to operate, namely does not need operators' intervention.On April 30, 1996, LIL Corporation obtained this advanced power supply to restore system's patent. But many companies still used the monitoring switch isolation breakdown; moreover majority uses the operator remote control to resume the power supply. This procedure time consuming moreover the efficiency is not high, especially in the snowstorm weather, many place presents the time which the line has a reason bonds is so.The power distribution management goal maintains invariableNewton Ivan’s studied the company to complete recently to this year power equipment'spower distribution management system management system plan second investigation, carried on this year first quarter in the first time research, to come from 20 countries to use electricity the unit officials to carry on the investigation. In 1996 springs this foundational research summary, has received the automation long term planning department's attention.To 1996 spring's investigation and study's brief review, indicated that this investigation including by reaches 125 to use electricity much unit's officials to the DMS goal rank division. This group of personnel believed that arranges in order in seven goals has two is quite important, namely shortest off time and smallest power failure scope, as well as enhancement to user's grade of service. The power distribution management system management system goal's rank division has 2/3 is important and is quite important. The definite power failure scope is the next most profitable target, and then reduces the actual cost.In the similar investigation, has been also provided by the investigators the communication relation which related DMS and other systems need. It is not strange, enumerates the direct real time link is to satisfy the following function to need, for example: Monitoring and data acquisition, power supply assignment, user information system as well as automatic plotting/device management/geographic information system.In the autumn research reported is using and the plan use communication way, but also confirmed in the early research discovery. Here rented the line and the two roads broadcast still played the influential role. Soon uses the plan, concentrates in the fiber optics, the binary channel communication and on the honey comb shaped communication system. The achievement which enumerates by the investigators stops in the plan the only communication way, is stops renting the line the use.翻译：配电自动化配电自动化可增加可靠性长岛照明公司凭借750条附加配电线路，主要是高架线路，向100多万用电单位提供供电服务。
电气毕业设计用外文翻译(中英文对照)
The Transformer on load ﹠Introduction to DC Machine sThe Transformer on loadIt has been shown that a primary input voltage 1V can be transformed to any desired open-circuit secondary voltage 2E by a suitable choice of turns ratio. 2E is available for circulating a load current impedance. For the moment, a lagging power factor will be considered. The secondary current and the resulting ampere-turns 22N I will change the flux, tending to demagnetize the core, reduce m Φ and with it 1E . Because the primary leakage impedance drop is so low, a small alteration to 1E will cause an appreciable increase of primary current from 0I to a new value of 1I equal to ()()i jX R E V ++111/. The extra primary current and ampere-turns nearly cancel the whole of the secondary ampere-turns. This being so , the mutual flux suffers only a slight modification and requires practically the same net ampere-turns 10N I as on no load. The total primary ampere-turns are increased by an amount 22N I necessary to neutralize the same amount of secondary ampere-turns. In the vector equation , 102211N I N I N I =+; alternatively, 221011N I N I N I -=. At full load, the current 0I is only about 5% of the full-load current and so 1I is nearly equal to 122/N N I . Because in mind that 2121/N N E E =, the input kV A which is approximately 11I E is also approximately equal to the output kV A, 22I E .The physical current has increased, and with in the primary leakage flux to which it is proportional. The total flux linking the primary ,111Φ=Φ+Φ=Φm p , is shown unchanged because the total back e.m.f.,（dt d N E /111Φ-）is still equal and opposite to 1V . However, there has been a redistribution of flux and the mutual component has fallen due to the increase of 1Φ with 1I . Although the change is small, the secondary demand could not be met without a mutual flux and e.m.f. alteration to permit primary current to change. The net flux s Φlinking the secondary winding has been further reduced by the establishment of secondary leakage flux due to 2I , and this opposes m Φ. Although m Φ and2Φ are indicated separately , they combine to one resultant in the core which will be downwards at the instant shown. Thus the secondary terminal voltage is reduced to dt d N V S /22Φ-= which can be considered in two components, i.e. dt d N dt d N V m //2222Φ-Φ-=or vectorially 2222I jX E V -=. As for the primary, 2Φ is responsible for a substantially constant secondaryleakage inductance 222222/Λ=ΦN i N . It will be noticed that the primary leakage flux is responsiblefor part of the change in the secondary terminal voltage due to its effects on the mutual flux. The two leakage fluxes are closely related; 2Φ, for example, by its demagnetizing action on m Φ has caused the changes on the primary side which led to the establishment of primary leakage flux.If a low enough leading power factor is considered, the total secondary flux and the mutual flux are increased causing the secondary terminal voltage to rise with load. p Φ is unchanged in magnitude from the no load condition since, neglecting resistance, it still has to provide a total back e.m.f. equal to 1V . It is virtually the same as 11Φ, though now produced by the combined effect of primary and secondary ampere-turns. The mutual flux must still change with load to give a change of 1E and permit more primary current to flow. 1E has increased this time but due to the vector combination with 1V there is still an increase of primary current.Two more points should be made about the figures. Firstly, a unity turns ratio has been assumed for convenience so that '21E E =. Secondly, the physical picture is drawn for a different instant of time from the vector diagrams which show 0=Φm , if the horizontal axis is taken as usual, to be the zero time reference. There are instants in the cycle when primary leakage flux is zero, when the secondary leakage flux is zero, and when primary and secondary leakage flux is zero, and when primary and secondary leakage fluxes are in the same sense.The equivalent circuit already derived for the transformer with the secondary terminals open, can easily be extended to cover the loaded secondary by the addition of the secondary resistance and leakage reactance.Practically all transformers have a turns ratio different from unity although such an arrangement issometimes employed for the purposes of electrically isolating one circuit from another operating at the same voltage. To explain the case where 21N N ≠ the reaction of the secondary will be viewed from the primary winding. The reaction is experienced only in terms of the magnetizing force due to the secondary ampere-turns. There is no way of detecting from the primary side whether 2I is large and 2N small or vice versa, it is the product of current and turns which causes the reaction. Consequently, a secondary winding can be replaced by any number of different equivalent windings and load circuits which will give rise to an identical reaction on the primary .It is clearly convenient to change the secondary winding to an equivalent winding having the same number of turns 1N as the primary.With 2N changes to 1N , since the e.m.f.s are proportional to turns, 2212)/('E N N E = which is the same as 1E .For current, since the reaction ampere turns must be unchanged 1222'''N I N I = must be equal to 22N I .i.e. 2122)/(I N N I =.For impedance , since any secondary voltage V becomes V N N )/(21, and secondary current I becomes I N N )/(12, then any secondary impedance, including load impedance, must become I V N N I V /)/('/'221=. Consequently, 22212)/('R N N R = and 22212)/('X N N X = .If the primary turns are taken as reference turns, the process is called referring to the primary side. There are a few checks which can be made to see if the procedure outlined is valid.For example, the copper loss in the referred secondary winding must be the same as in the original secondary otherwise the primary would have to supply a different loss power. ''222R I must be equal to 222R I . ）222122122/()/(N N R N N I ∙∙ does in fact reduce to 222R I .Similarly the stored magnetic energy in the leakage field )2/1(2LI which is proportional to 22'X I will be found to check as ''22X I . The referred secondary 2212221222)/()/(''I E N N I N N E I E kVA =∙==.The argument is sound, though at first it may have seemed suspect. In fact, if the actual secondarywinding was removed physically from the core and replaced by the equivalent winding and load circuit designed to give the parameters 1N ,'2R ,'2X and '2I , measurements from the primary terminals would be unable to detect any difference in secondary ampere-turns, kVA demand or copper loss, under normal power frequency operation.There is no point in choosing any basis other than equal turns on primary and referred secondary, but it is sometimes convenient to refer the primary to the secondary winding. In this case, if all the subscript 1’s are interchanged for the subscript 2’s, the necessary referring constants are easily found; e.g. 2'1R R ≈,21'X X ≈; similarly 1'2R R ≈ and 12'X X ≈.The equivalent circuit for the general case where 21N N ≠ except that m r has been added to allow for iron loss and an ideal lossless transformation has been included before the secondary terminals to return '2V to 2V .All calculations of internal voltage and power losses are made before this ideal transformation is applied. The behaviour of a transformer as detected at both sets of terminals is the same as the behaviour detected at the corresponding terminals of this circuit when the appropriate parameters are inserted. The slightly different representation showing the coils 1N and 2N side by side with a core in between is only used for convenience. On the transformer itself, the coils are , of course , wound round the same core.Very little error is introduced if the magnetising branch is transferred to the primary terminals, but a few anomalies will arise. For example ,the current shown flowing through the primary impedance is no longer the whole of the primary current. The error is quite small since 0I is usually such a small fraction of 1I . Slightly different answers may be obtained to a particular problem depending on whether or not allowance is made for this error. With this simplified circuit, the primary and referred secondary impedances can be added to give: 221211)/(Re N N R R += and 221211)/(N N X X Xe +=It should be pointed out that the equivalent circuit as derived here is only valid for normal operation at power frequencies; capacitance effects must be taken into account whenever the rate of change of voltage would give rise to appreciable capacitance currents, dt CdV I c /=. They are important at high voltages and at frequencies much beyond 100 cycles/sec. A further point is not theonly possible equivalent circuit even for power frequencies .An alternative , treating the transformer as a three-or four-terminal network, gives rise to a representation which is just as accurate and has some advantages for the circuit engineer who treats all devices as circuit elements with certain transfer properties. The circuit on this basis would have a turns ratio having a phase shift as well as a magnitude change, and the impedances would not be the same as those of the windings. The circuit would not explain the phenomena within the device like the effects of saturation, so for an understanding of internal behaviour .There are two ways of looking at the equivalent circuit:(a) viewed from the primary as a sink but the referred load impedance connected across '2V ,or (b) viewed from the secondary as a source of constant voltage 1V with internal drops due to 1Re and 1Xe . The magnetizing branch is sometimes omitted in this representation and so the circuit reduces to a generator producing a constant voltage 1E (actually equal to 1V ) and having an internal impedance jX R + (actually equal to 11Re jXe +).In either case, the parameters could be referred to the secondary winding and this may save calculation time .The resistances and reactances can be obtained from two simple light load tests.Introduction to DC MachinesDC machines are characterized by their versatility. By means of various combination of shunt, series, and separately excited field windings they can be designed to display a wide variety of volt-ampere or speed-torque characteristics for both dynamic and steadystate operation. Because of the ease with which they can be controlled , systems of DC machines are often used in applications requiring a wide range of motor speeds or precise control of motor output.The essential features of a DC machine are shown schematically. The stator has salient poles and is excited by one or more field coils. The air-gap flux distribution created by the field winding is symmetrical about the centerline of the field poles. This axis is called the field axis or direct axis.As we know , the AC voltage generated in each rotating armature coil is converted to DC in the external armature terminals by means of a rotating commutator and stationary brushes to which the armature leads are connected. The commutator-brush combination forms a mechanical rectifier,resulting in a DC armature voltage as well as an armature m.m.f. wave which is fixed in space. The brushes are located so that commutation occurs when the coil sides are in the neutral zone , midway between the field poles. The axis of the armature m.m.f. wave then in 90 electrical degrees from the axis of the field poles, i.e., in the quadrature axis. In the schematic representation the brushes are shown in quarature axis because this is the position of the coils to which they are connected. The armature m.m.f. wave then is along the brush axis as shown.. (The geometrical position of the brushes in an actual machine is approximately 90 electrical degrees from their position in the schematic diagram because of the shape of the end connections to the commutator.)The magnetic torque and the speed voltage appearing at the brushes are independent of the spatial waveform of the flux distribution; for convenience we shall continue to assume a sinusoidal flux-density wave in the air gap. The torque can then be found from the magnetic field viewpoint.The torque can be expressed in terms of the interaction of the direct-axis air-gap flux per pole d Φ and the space-fundamental component 1a F of the armature m.m.f. wave . With the brushes in the quadrature axis, the angle between these fields is 90 electrical degrees, and its sine equals unity. For a P pole machine 12)2(2a d F P T ϕπ= In which the minus sign has been dropped because the positive direction of the torque can be determined from physical reasoning. The space fundamental 1a F of the sawtooth armature m.m.f. wave is 8/2π times its peak. Substitution in above equation then gives a d a a d a i K i mPC T ϕϕπ==2 Where a i =current in external armature circuit;a C =total number of conductors in armature winding;m =number of parallel paths through winding;And mPC K a a π2=Is a constant fixed by the design of the winding.The rectified voltage generated in the armature has already been discussed before for an elementary single-coil armature. The effect of distributing the winding in several slots is shown in figure ,in which each of the rectified sine waves is the voltage generated in one of the coils, commutation taking place at the moment when the coil sides are in the neutral zone. The generated voltage as observed from the brushes is the sum of the rectified voltages of all the coils in series between brushes and is shown by the rippling line labeled a e in figure. With a dozen or so commutator segments per pole, the ripple becomes very small and the average generated voltage observed from the brushes equals the sum of the average values of the rectified coil voltages. The rectified voltage a e between brushes, known also as the speed voltage, is m d a m d a a W K W mPC e ϕϕπ==2 Where a K is the design constant. The rectified voltage of a distributed winding has the same average value as that of a concentrated coil. The difference is that the ripple is greatly reduced.From the above equations, with all variable expressed in SI units:m a a Tw i e =This equation simply says that the instantaneous electric power associated with the speed voltage equals the instantaneous mechanical power associated with the magnetic torque , the direction of power flow being determined by whether the machine is acting as a motor or generator.The direct-axis air-gap flux is produced by the combined m.m.f. f f i N ∑ of the field windings, the flux-m.m.f. characteristic being the magnetization curve for the particular iron geometry of the machine. In the magnetization curve, it is assumed that the armature m.m.f. wave is perpendicular to the field axis. It will be necessary to reexamine this assumption later in this chapter, where the effects of saturation are investigated more thoroughly. Because the armature e.m.f. is proportional to flux timesspeed, it is usually more convenient to express the magnetization curve in terms of the armature e.m.f. 0a e at a constant speed 0m w . The voltage a e for a given flux at any other speed m w is proportional to the speed,i.e. 00a m m a e w w e Figure shows the magnetization curve with only one field winding excited. This curve can easily be obtained by test methods, no knowledge of any design details being required.Over a fairly wide range of excitation the reluctance of the iron is negligible compared with that of the air gap. In this region the flux is linearly proportional to the total m.m.f. of the field windings, the constant of proportionality being the direct-axis air-gap permeance.The outstanding advantages of DC machines arise from the wide variety of operating characteristics which can be obtained by selection of the method of excitation of the field windings. The field windings may be separately excited from an external DC source, or they may be self-excited; i.e., the machine may supply its own excitation. The method of excitation profoundly influences not only the steady-state characteristics, but also the dynamic behavior of the machine in control systems.The connection diagram of a separately excited generator is given. The required field current is a very small fraction of the rated armature current. A small amount of power in the field circuit may control a relatively large amount of power in the armature circuit; i.e., the generator is a power amplifier. Separately excited generators are often used in feedback control systems when control of the armature voltage over a wide range is required. The field windings of self-excited generators may be supplied in three different ways. The field may be connected in series with the armature, resulting in a shunt generator, or the field may be in two sections, one of which is connected in series and the other in shunt with the armature, resulting in a compound generator. With self-excited generators residual magnetism must be present in the machine iron to get the self-excitation process started.In the typical steady-state volt-ampere characteristics, constant-speed primemovers being assumed. The relation between the steady-state generated e.m.f. a E and the terminal voltage t V isa a a t R I E V -=Where a I is the armature current output and a R is the armature circuit resistance. In a generator, a E is large than t V ; and the electromagnetic torque T is a countertorque opposing rotation.The terminal voltage of a separately excited generator decreases slightly with increase in the load current, principally because of the voltage drop in the armature resistance. The field current of a series generator is the same as the load current, so that the air-gap flux and hence the voltage vary widely with load. As a consequence, series generators are not often used. The voltage of shunt generators drops off somewhat with load. Compound generators are normally connected so that the m.m.f. of the series winding aids that of the shunt winding. The advantage is that through the action of the series winding the flux per pole can increase with load, resulting in a voltage output which is nearly constant. Usually, shunt winding contains many turns of comparatively heavy conductor because it must carry the full armature current of the machine. The voltage of both shunt and compound generators can be controlled over reasonable limits by means of rheostats in the shunt field. Any of the methods of excitation used for generators can also be used for motors. In the typical steady-state speed-torque characteristics, it is assumed that the motor terminals are supplied from a constant-voltage source. In a motor the relation between the e.m.f. a E generated in the armature and the terminal voltage t V isa a a t R I E V +=Where a I is now the armature current input. The generated e.m.f. a E is now smaller than the terminal voltage t V , the armature current is in the opposite direction to that in a motor, and the electromagnetic torque is in the direction to sustain rotation ofthe armature.In shunt and separately excited motors the field flux is nearly constant. Consequently, increased torque must be accompanied by a very nearly proportional increase in armature current and hence by a small decrease in counter e.m.f. to allow this increased current through the small armature resistance. Since counter e.m.f. is determined by flux and speed, the speed must drop slightly. Like the squirrel-cage induction motor ,the shunt motor is substantially a constant-speed motor having about 5 percent drop in speed from no load to full load. Starting torque and maximum torque are limited by the armature current that can be commutated successfully.An outstanding advantage of the shunt motor is ease of speed control. With a rheostat in the shunt-field circuit, the field current and flux per pole can be varied at will, and variation of flux causes the inverse variation of speed to maintain counter e.m.f. approximately equal to the impressed terminal voltage. A maximum speed range of about 4 or 5 to 1 can be obtained by this method, the limitation again being commutating conditions. By variation of the impressed armature voltage, very wide speed ranges can be obtained.In the series motor, increase in load is accompanied by increase in the armature current and m.m.f. and the stator field flux (provided the iron is not completely saturated). Because flux increases with load, speed must drop in order to maintain the balance between impressed voltage and counter e.m.f.; moreover, the increase in armature current caused by increased torque is smaller than in the shunt motor because of the increased flux. The series motor is therefore a varying-speed motor with a markedly drooping speed-load characteristic. For applications requiring heavy torque overloads, this characteristic is particularly advantageous because the corresponding power overloads are held to more reasonable values by the associated speed drops. Very favorable starting characteristics also result from the increase in flux with increased armature current.In the compound motor the series field may be connected either cumulatively, so that its.m.m.f.adds to that of the shunt field, or differentially, so that it opposes. The differential connection is very rarely used. A cumulatively compounded motor hasspeed-load characteristic intermediate between those of a shunt and a series motor, the drop of speed with load depending on the relative number of ampere-turns in the shunt and series fields. It does not have the disadvantage of very high light-load speed associated with a series motor, but it retains to a considerable degree the advantages of series excitation.The application advantages of DC machines lie in the variety of performance characteristics offered by the possibilities of shunt, series, and compound excitation. Some of these characteristics have been touched upon briefly in this article. Still greater possibilities exist if additional sets of brushes are added so that other voltages can be obtained from the commutator. Thus the versatility of DC machine systems and their adaptability to control, both manual and automatic, are their outstanding features.负载运行的变压器及直流电机导论负载运行的变压器通过选择合适的匝数比，一次侧输入电压1V 可任意转换成所希望的二次侧开路电压2E 。
电气工程及其自动化本科毕业设计(论文)中英文对照翻译-电力系统
本科毕业设计（论文）中英文对照翻译院（系部）电气工程与自动化学院专业名称电气工程及其自动化年级班级03级2班学生姓名指导老师电力系统1 电力的技术特点电力具有独特的技术特点，这使得电力工业具有独特的行业特点。
1.无形性。
用户不能用人体感官直接察觉千瓦时的用电量。
2.质量。
供电质量可由供电连续性或供电可靠性、在标准电压等级下的电压均等性、交流电压频率的正确不变性来度量。
3.电力的贮存。
与大多数行业不同，电力部门必须随时根据用电的需求生产出电力来，因为电能无法贮存。
4.对供电负责。
电由电力部门输送到用户，因此必须对安全、可靠供电负责。
5.对公众的安全。
电力部门须对公众及其技术人员提供稳妥的保护。
2 电力系统的规划预期到电力部门的供电负荷将持续增长，电力系统的容量也持续增大。
远期规划主要是保证这种扩建在技术上是适宜的，在造价上是合理的，与增长模式是相符的。
远期规划者碰到的困难包括：不同地域和不同时间负荷增长的不确定性、新发明新技术发展的可能性。
优异的系统规划要努力做到全系统设计的最优化，而不能为了系统某部分造价的最小化而不顾其它部分的影响。
近年来，已经强调了规划和运行的经济性。
现在则越来越强调可靠性和环境方面的因素。
在作出规划前，须要仔细考虑许多因素：（1）设备的决策具有远期效应，这需要15—25年的预期和研究。
（2）有许多发电途径可选择：核电、基荷火电、中等规模燃气轮机发电或水电，以及大型、中型、小型电厂和各种形式的蓄能。
（3）有多种送电途径可选择，例如由交流或直流，架空线或地下电缆送电并有各种电压等级。
（4）规划决策受负荷管理技术和负荷模式的影响。
（5）有关因素存在不确定性。
如将来燃料价格货币的利率资金的来源设备的强迫停运率新技术环境的要求。
3 电力分配3.1 最初的分配系统发电厂和最后的各支路之间的分配线路叫做最初的分配系统。
在这两个电力系统之间传输有多种方法. 其中最常见的两种方法是辐射式和环绕式。
电气外文文献及翻译---高层建筑供配电系统设计 精品
Power supply system of high-rise building designAbstract: With the continuous development of city size, more and more high-rise buildings, therefore, high-rise building electrical design to the designers had to face. In this paper, an engineering example, describes the electrical design of high-rise buildings and some of the more typical issues of universal significance, combined with the actual practice of an engineering solution to the problem described.Key words: high-rise building; electrical design; distribution; load calculation1 Project OverviewThe commercial complex project, with a total construction area of 405570m2, on the ground floor area of 272330m2, underground construction area of 133240m2, the main height of 99m. Project components are: two office buildings, construction area is 70800m2, 28 layers, the standard story is 3.2m.2 Load Calculation1) Load characteristics: electric load, much larger than the "national civil engineering technical measures" Large 120W/m2 indicators, especially in the electricity load more food, and different types of food and beverage catering different cultural backgrounds also high.2) the uncertainty of a large load, because the commercial real estate rents are often based on market demand, and constantly adjust the nature of the shops, making the load in the dynamic changes.3) There is no specification and technical measures in the different types of commercial projects refer to the detailed parameters of the shops, engineering design load calculation in the lack of data, in most cases to rely on staff with previous experience in engineering design calculations. Load the selection of parameters: for the above problems, the load calculation, the first developer of sales and good communication, to determine the form of layers of the forms and nature of floor area, which is calculated on the basis of electrical load basis; followed to determine parameter index within the unit area of shops is also very important and complex because there is no clear indicator of the specification can refer to; and different levels of economic development between cities is not balanced, power indices are also different; will be in the same city, different regions have different consumer groups .3) the need to factor in the choice: parameters determined, the need for load calculation. Need to factor commonly used method, the calculation will not repeat them. Need to explore is the need for coefficient selection, which in the current specifications, manuals and the "unified technical measures" is also not clear requirements, based on years of design experience that most end shops in the distribution or level within the household distribution box with case Kx generally take a while, in the calculation of the loop route to take 0.7 to 0.8, the distribution transformers in the substation calculations take 0.4 to 0.6.3 substations setLoad calculation based on the results of this project the total installed capacity of transformer 43400Kv.A, after repeated consultations with the power company, respectively, in the project innorthern, central and southern three sections set the three buildings into three power substations, 1 # set 6 sets 2500Kv.A transformer substation, take the northern section of power supply; 2 # 4 1600Kv.A transformer substations located, plus 6 sets 2000Kv.A transformers, take the middle of the power supply, in addition to 5 Taiwan 10Kv.A high-pressure water chillers (total 4000Kv.A); 3 # substation located 2 units plus 2 units 1000Kv.A 2000Kv.A transformers, take the southern section of A, B two office supply. 10Kv power configuration of this project into two points, each at the two 10Kv lines, the power company under the provisions of 10Kv power capacity: maximum load per channel is about to 11000Kv.A, two is the 22000Kv.A, design # 1 , 3 # combination of a substation 10Kv, power line, with a total capacity of 21000Kv.A; 2 # substation transformers and 10Kv, 10Kv chillers sharing a power line, with a total capacity of 22400Kv.A. The design of the substation layout, in addition to meeting regulatory requirements, it also need to consider the high-pressure cabinets, transformers and low voltage power supply cabinet by order of arrangement, especially in low voltage distribution cabinet to feed the cable smooth and easy inspection duty problems are not seriously consider the construction of the cable crossing will cause more long detour, a waste of floor space, and convenient inspections and other issues.4 small fire load power supplyIn the design of large commercial projects often encounter small fire load of electrical equipment and more dispersed distribution, if fed by a substation, a substation will be fed a lot of low-voltage low-current counter circuit breaking capacity circuit breaker and conductor of the dynamic and thermal stability in a certain extent. According to GB50045-1995 "fire protection design of tall buildings," rule "should be used in Fire Equipment dedicated power supply circuit, the power distribution equipment shall be provided with clear signs." Interpretation of the provisions of the power supply circuit means "from the low-voltage main distribution room (including the distribution of electrical room) to last a distribution box, and the general distribution lines should be strictly separated." In this design, the use of methods to increase the level of distribution, that is different from the substation bus segments, respectively, a fire fed a special circuit, set in place two distribution cabinets, distribution cabinets and then the resulting radial allocated to the end of the dual power to vote each box, so that not only meets the specification requirements for dedicated power supply circuit, but also to avoid feeding the substation level of many small current loop.5, the choice of circuit breaker and conductorCommercial real estate projects use the room as the uncertainty in the choice of circuit breakers and conductors must be considered in a certain margin to meet the needs caused by adjustment of the load changes. According to this characteristic, increased use in the design of the plug bus-powered, not only meet the requirements of large carrying capacity, and also allows the flexibility to increase supply and distribution, are reserved in each shaft in the plug-box backup in order to change, according to changes in upper and lower load, to adjust. For example: a bus is responsible for a shaft 1 to 3 layers of power, when a layer due to the change in capacity increases, while the 3-layer capacity is reduced, you can use a spare plug box layer off the 3-layer 1 layer capacity rationing . This level distribution in the substation, select the circuit breaker to choose the setting value when the circuit breaker to adjust to changes at the end to adjust the load setting value; in the bus and the transformer circuit breaker according to the choice of the general framework of values to select . For example: Route certain equipment capacity 530Kv, Kx take 0.7 to calculate current of 704A, select the frame circuit breaker is 1000A, tuning is 800A; currenttransformer for the 1000/50; bus carrying capacity for the 1000A, this road can meet the maximum 1000A current load requirements, even if there is adjustment, power distribution switches and circuit can not make big changes.6 layer distribution box setAccording to the division of layers of fire protection district, respectively numbered as A ~ K layers within the set level shaft for the retail lighting power distribution box, with one on one power supply shops in radial power. Should be noted that the forms of the complex layers of layers of fire partition, does not correspond to the lower, making some of shaft power in charge of the fire district at the same time, also responsible for the power supply adjacent to the fire district. At design time, using the principle of proximity, while also taking into account the burden of the whole trunk load conditions, so that each shaft as far as possible a more balanced load.7 public area distribution box setTaking into account the future needs of the business re-decoration of public areas must be reserved for power. Here the design needs to consider the following points: ①question of how much reserve power, lighting and electricity, which according to GB50034-2004"Architectural Lighting Design Standards" table of Article 6.1.3 and 6.1.8, commercial building lighting power density value, high-end supermarkets, business offices as 20W/m2, under the "decorative lighting included 50% of the total lighting power density calculation" requirements, using the reserved standard 40W/m2. ②In order to facilitate the decoration in each partition set fire lighting in public areas and emergency lighting distribution box distribution box, in order to identify the electrical power distribution decoration cut-off point.③the staircase, storage rooms and other parts of the decoration does not need to do, set the power distribution circuit or a separate distribution box, try not to be reserved from the public area of electricity distribution board fed hardcover out.④control of lighting in public areas, the majority in two ways, namely, C-BUS control system or the BA system, the use of C-BUS has the advantage of more flexible control, each road can be fed out of control, adjustable light control; shortcomings is a higher cost. BA system control advantages of using low cost, simple control; disadvantage is that the exchanges and contacts for the three-phase, three-way control may be related both to open, or both, in the decoration of the contacts required to feed the power supply circuit diverge to avoid failure blackouts.Design of distribution box 8In the commercial real estate design, shop design is often only a meter box, and outlet route back to the needs of the user according to their second design, but the shops are difficult to resolve within the power supply fan coil units, air-conditioning system as a whole can not debug. The project approach is to add a circuit breaker in the meter box for the coil power supply, another way for users to use the second design, as shown below.User distribution box design9 distribution cabinet / box number and distribution circuitsLarge-scale projects are often low voltage distribution cabinet / box number, low-voltage circuits to feed the more often there will be cabinet / box number and line number duplication, resulting in the design and the future looks difficult maintenance and overhaul. The project has three 10Kv substations, 20 transformer, hundreds of low-voltage fed out of the closet, fed the circuit more. Accordance with the International Electrotechnical Commission (IEC) and the Chinese nationalstandard requirements: ①All the distribution number to be simple and clear, not too box and line numbers are not repeated. ②number to simple and clear, not too long. ③distinction between nature and type of load. ④law was easy to find, make viewer at a glance. Based on the above requirements and on the ground, fire district and the underground construction industry form the different conditions, using two slightly different ways. Essential for the underground garage, uses a single comparison, also relatively fire district neat, according to fire district number, such as AL-BL-1 / 1, AP and APE, the meaning of the letters and numbers: AL on behalf of lighting distribution (AP on behalf of Power distribution box, APE on behalf of the emergency power distribution box); BI on behalf of the basement; 1 / 1 for partition 1, I fire box. Above ground is more complex, more fire district, and on the fire district does not correspond to the lower, according to shaft number is better, such as AL-1-A1, AP, and APE, letters and numbers mean: 1 represents a layer; A1 on behalf of A, No. 1 shaft fed a distribution box. Fed a low-voltage circuits, such as the number of uses: W3-6-AL-1-A1, W3-6) indicates that the route back to power supply transformer 3, 6, feed the power distribution cabinet, AL-1-A1, said the then the first loop of the distribution box for the AL-1-A1 and so on, and so on.10 ConclusionWith more and more complex commercial design projects, designers need to continually improve the design level, designed to make fine. These are only bits of the design in the business lessons learned, and the majority of designers want to communicate高层建筑供配电系统设计摘要：随着城市规模的不断发展，高层建筑越来越多，因此，高层建筑电气设计就成为设计者不得不面对的问题。
电气工程及其自动化专业毕业论文外文翻译
本科毕业设计(论文)中英文对照翻译院(系部）工程学院专业名称电气工程及其自动化年级班级 11级2班学生姓名蔡李良指导老师赵波Infrared Remote Control SystemAbstractRed outside data correspondence the technique be currently within the scope of world drive extensive usage of a kind of wireless conjunction technique, drive numerous hardware and software platform support。
Red outside the transceiver product have cost low，small scaled turn, the baud rate be quick，point to point SSL, be free from electromagnetism thousand Raos etc. characteristics，can realization information at dissimilarity of the product fast，convenience，safely exchange and transmission, at short distance wireless deliver aspect to own very obvious of advantage。
Along with red outside the data deliver a technique more and more mature, the cost descend, red outside the transceiver necessarily will get at the short distance communication realm more extensive of application.The purpose that design this s ystem is transmit customer’s operation information with infrared rays for transmit media, then demodulate original signal with receive circuit。
毕业设计毕业论文电气工程及其自动化外文翻译中英文对照
毕业设计毕业论文电气工程及其自动化外文翻译中英文对照电气工程及其自动化外文翻译中英文对照一、引言电气工程及其自动化是一门涉及电力系统、电子技术、自动控制和信息技术等领域的综合学科。
本文将翻译一篇关于电气工程及其自动化的外文文献，并提供中英文对照。
二、文献翻译原文标题：Electric Engineering and Its Automation作者：John Smith出版日期：2020年摘要：本文介绍了电气工程及其自动化的基本概念和发展趋势。
首先，介绍了电气工程的定义和范围。
其次，探讨了电气工程在能源领域的应用，包括电力系统的设计和运行。
然后，介绍了电气工程在电子技术领域的重要性，包括电子设备的设计和制造。
最后，讨论了电气工程与自动控制和信息技术的结合，以及其在工业自动化和智能化领域的应用。
1. 介绍电气工程是一门研究电力系统和电子技术的学科，涉及发电、输电、配电和用电等方面。
电气工程的发展与电力工业的发展密切相关。
随着电力需求的增长和电子技术的进步，电气工程的重要性日益凸显。
2. 电气工程在能源领域的应用电气工程在能源领域的应用主要包括电力系统的设计和运行。
电力系统是由发电厂、输电线路、变电站和配电网络等组成的。
电气工程师负责设计和维护这些设施，以确保电力的可靠供应。
3. 电气工程在电子技术领域的重要性电气工程在电子技术领域的重要性体现在电子设备的设计和制造上。
电子设备包括电脑、手机、电视等消费电子产品，以及工业自动化设备等。
电气工程师需要掌握电子电路设计和数字信号处理等技术，以开发出高性能的电子设备。
4. 电气工程与自动控制和信息技术的结合电气工程与自动控制和信息技术的结合是电气工程及其自动化的核心内容。
自动控制技术可以应用于电力系统的运行和电子设备的控制，以提高系统的稳定性和效率。
信息技术则可以用于数据采集、处理和传输，实现对电力系统和电子设备的远程监控和管理。
5. 电气工程在工业自动化和智能化领域的应用电气工程在工业自动化和智能化领域的应用越来越广泛。
(完整版)电气工程毕业设计外文资料翻译
附录：外文资料翻译外文资料原文：A Virtual Environment for Protective Relaying Evaluationand TestingA. P. Sakis Meliopoulos and George J. CokkinidesAbstract—Protective relaying is a fundamental discipline of power system engineering. At Georgia Tech, we offer three courses that cover protective relaying: an undergraduate course that devotes one-third of the semester on relaying, a graduate courseentitled “Power System Protection,” and a three-and-a- the concepts,theory, and technology associated with protective relaying, we a virtual environment. The virtual environment includes a) a power system simulator, b) a simulator of instrumentation for protective relaying with visualization and animation modules, c) specific protective relay models with visualization and animation modules, and d) interfaces to be performed. We refer to this set of software as the “virtual power system.” The virtual power system permits the in-depth coverage of the protective relaying concepts in minimum time and maximizes student understanding. The tool is not used in a passive way. Indeed, the students actively participate with well-designed projects such as a) design and implementation of multifunctional relays, b) relay testing for specific disturbances, etc. The paper describes the virtual power system organization and “engines,” such as solver, visualization, and animation of protective relays, etc. It also discusses the utilization of this tool in the courses via specific applicationexamples and student assignments.Index Terms—Algebraic companion form, animation, relaying,time-domain simulation, visualization.I. INTRODUCTIONRELAYING the security and reliability of electric power systems. As the technology advances, relaying of the system. It is indisputable that relaying the safety of systems and protection of equipment. Yet, because of the complexity of the system and multiplicity of competing factors, relaying is a challenging discipline.Despite all of the advances in the field, unintended relay operations (misoperations) do occur. Many events of outages and blackouts can be attributed to inappropriate relaying settings, unanticipated system conditions, and inappropriate selection of instrument transformers. Design of relaying schemes strives to anticipate all possible conditions for the purpose of avoiding undesirable operations. Practicing relay engineers utilize a two-step procedure to minimize the possibility of such events. First, in the design phase, comprehensive analyses are utilized to determine the best relaying schemes and settings. Second, if such an event occurs, an exhaustive post-mortem analysis is performed to reveal the root cause of the event and what “was missed” in the design phase. The post-mortem analysis of these events is facilitated with the existing technology of disturbance recordings (via fault disturbance recorders or embedded in numerical relays). This process results in accumulation of experience that passes from one generation of engineers to the next.An important challenge for educators is the training of students tobecome effective protective relaying engineers. Students must be provided with an understanding of relaying technology that encompasses the multiplicity of the relaying functions, communications, protocols, and automation. In addition, a deep understanding of power system operation and behavior during disturbances is necessary for correct relaying applications. In today’s crowded curricula, the challenge is to achieve this training within a very short period of time, for example, one semester. This paper presents an approach to meet this challenge. Specifically, we propose the concept of the virtual power system for the purpose of teaching students the complex topic of protective relaying within a short period of time.The virtual power system approach is possible because of two factors: a) recent developments in software engineering and visualization of power system dynamic responses, and b) the new generation of power system digital-object-oriented relays. Specifically, it is possible to integrate simulation of the power system, visualization, and animation of relay response and relay testing within a virtual environment. This approach permits students to study complex operation of power systems and simultaneously observe relay response with precision and in a short time.The paper is organized as follows: First, a brief description of the virtual power system is provided. Next, the mathematical models to enable the features of the virtual power system are presented together with the modeling approach for relays and relay instrumentation. Finally, few samples of applications of this tool for educational purposes are presented. II. VIRTUAL POWER SYSTEMThe virtual power system integrates a number of application software in a multitasking environment via a unified graphical user interface. The application software includes a) a dynamic power system simulator, b) relay objects, c) relay instrumentation objects, and d) animation and visualization objects. The virtual power system simulation of the system under study;2) ability to modify (or fault) the system under study during the simulation, and immediately observe the effects of thechanges;3) advanced output data visualization options such as animated 2-D or 3-D displays that illustrate the operation of any device in the system under study.The above properties are fundamental for a virtual environment intended for the study of protective relaying. The first property guarantees the uninterrupted operation of the system under study in the same way as in a physical laboratory: once a system assembled, it will continue to operate. The second property guarantees the ability to connect and disconnect devices into the system without interrupting the simulation of the system or to apply disturbances such as a fault. This property duplicates the capability of physical laboratories where one can connect a component to the physical system and observe the reaction immediately (e.g., connecting a new relay to the system and observing the operation of the protective relaying logic, applying a disturbance and observing the transients as well as the relay logic transients, etc.). The third property duplicates the ability to observe the simulated system operation, in a similar way as in a physical laboratory. Unlike the physical laboratorywhere one cannot observe the internal operation of a relay, motor, etc., the virtual power system and animation of the internal “workings” of a relay, motor, etc. This capability to animate and visualize the internal “workings” of a relay, an instrumentation channel, or any other device is based on the MS Windows multidocument-viewarchitecture. Each document object constructs a single solver object, which computations. The simulated system is represented by a set of objects—one for each system device (i.e. generators, motors, transmission lines, relays, etc). The document object can generate any number of view window objects. Two basic view classes are available: a) schematic views and b) result visualization views. Schematic view objects allow the user to define the simulated system connectivity graphically, by manipulating a single line diagram using the mouse. Result visualization views allow the user to observe calculated results in a variety of ways. Several types of result visualization views are supported and will be discussed later.Fig. 1 illustrates the organization of device objects, network solver, and view objects and their interactions. The network solver object is the basic engine that provides the time-domain solution of the device operating conditions. To maintain object orientation, each device is represented with a generalized mathematical model of a specific structure, the algebraic companion form (ACF). The mathematics of the algebraic companion form are described in the next section. Implementationwise, the network solver is an independent background computational thread, allowing both schematic editor and visualization views to be active during the simulation. The network solver continuously updates the operating states of the devicesand “feeds” all other applications, such as visualization views,etc.The network solver speed is user selected, thus allowing speeding-up or slowing-down the visualization and animation speed. The multitasking environment permits system topology changes, device parameter changes, or connection of new devices (motors, faults) to the system during the simulation. In this way, the user can immediately observe the system response in the visualization views.The network solver interfaces with the device objects. This interface requires at minimum three virtual functions:Initialization: The solver calls this function once before the simulation starts. It initializes all device-dependent parameters and models needed during the simulation.Reinitialization: The solver calls this function any time the user modifies any device parameter. Its function is similar to the initialization virtual function.Time step: The solver calls this function at every time step of the time-domain simulation. It transfers the solution from the previous time step to the device object and updates the algebraic companion form of the device for the next time step (see next section “network solver.”) In addition to the above functions, a device object the schematic editor graphical user interface. Specifically,the device diagram can be moved, resized, and copied using the mouse. Also, a function is included in this set, which implements a device parameter editing dialog window which “pops-up” by double clicking o n the device icon. Furthermore,the schematic module interface allows for device icons that reflect thedevice status. For example, a breaker schematic icon can be implemented to indicate the breaker status.Finally, each device class (or a group of device classes) may optionally include a visualization module, consisting of a set of virtual functions that and animation output. The visualization module interface allows for both two-dimensional (2-D) and three-dimensional (3-D) graphics. Presently, 2-D output is implemented via the Windows graphical device interface (GDI) standard. The 3-D output is implemented using the open graphics library (OpenGL). Both 2-D and 3-D outputs generate animated displays, which are dynamically updated by the network solver to reflect the latest device state. The potential applications of 2-D or 3-D animated visualization objects are only limited by the imagination of the developer. These objects can generate photorealistic renderings of electromechanical components that clearly illustrate their internal operation and can be viewed from any desired perspective,slowed down, or paused for better observation.III. NETWORK SOLVERAny power system device is described with a set of algebraicdifferential-integral equations. These equations are obtained directlyfrom the physical construction of the device. It is alwayspossible to cast these equations in the following general formNote that this form includes two sets of equations, which arenamed external equations and internal equations, respectively.The terminal currents appear only in the external equations.Similarly, the device states consist of two sets: external states[i.e., terminal voltages, v(t)] and internal states [i.e. y(t)]. Theset of (1) is consistent in the sense that the number of externalstates and the numberof internal states equals the number of externaland internal equations, respectively.Note that (1) may contain linear and nonlinear terms. Equation(1) is quadratized (i.e., it is converted into a set of quadraticequations by introducing a series of intermediate variables and expressing the nonlinear components in terms of a series of quadratic terms). The resulting equations are integrated using a suitable numerical integration method. Assuming an integration time step is given with a second-order equation of the formwhere , are past (2) is referred to as the algebraic companion form (ACF) of the device model. Note that this form is a generalizationof the resistive companion form (RCF) that is used by the EMTP [3]. The difference is that the RCF is a linear model that represents a linearized equivalent of the device while the ACF is quadratic and represents the detailed model of the device.The network solution is obtained by application of Kirchoff’s current law at each node of the system (connectivity constraints). This procedure results in the set of (3). To these equations, the internal equations are appended resulting to the following set of equations:(3)internal equations of all devices (4)where is a component incidence matrix withif node of component is connected to node otherwise is the vector of terminal currents of component k.Note that (3) correspond one-to-one with the external system states while (4) correspond one-to-one with the internal system states. The vector of component k terminal voltages isrelated to the nodal voltage vector by(5)Upon substitution of device (2), the set of (3) and (4) become a set of quadratic equations (6)where x(t) is thevector of all external and internal system states.These equations are solved using Newton’s method. Specifically,the solution is given by the following expression(7)where is the Jacobian matrix of (6) and are the values ofthe state variables at the previous iteration.IV. RELAY INSTRUMENTATION MODELINGRelays and, in general, IEDs use a system of instrument transformers to scale the power system voltages and currents into instrumentation level voltages and currents. Standard instrumentation level voltages and currents are 67 V or 115 V and 5 A, respectively. These standards were established many years ago to accommodate the electromechanical relays. Today, the instrument transformers are still in use but because modern relays (and IEDs) operate at much lower voltages, it is necessary to apply an additional transformation to the new standard voltages of 10 or 2 V. This means that the modern instrumentation channel consists of typically two transformations and additional wiring and possibly burdens. Fig. 2 illustrates typical instrumentation channels, a voltage channel and a current channel. Note that each component of the instrumentation channel will introduce an error. Of importance is the net error introduced by all of the components of the instrumentation channel. The overallerror can be defined as follows. Let the voltage or current at the power system be and , respectively. An ideal instrumentation channel will generate a waveform at the output of the channel that will be an exact replica of the waveform at the power system. If the nominal transformation ratio is and for the voltage and current instrumentation channels, respectively, then the output of an “ideal” system and the instrumentation channel error will bewherethe subscript “out” refers to the actual output of the instrumentation channel. The error waveforms can be analyzed to provide the rms value of the error, the phase error, etc.Any relaying course should include the study of instrumentation channels. The virtual power system is used to study the instrumentation error by including an appropriate model of the entire instrumentation channel. It is important to model the saturation characteristics of CTs and PTs, resonant circuits of CCVTs, etc. (see [6]). In the virtual power system, models of instrumentation channel components developed. The resulting integrated model provides, with precision, the instrumentation channel error.With the use of animation methods, one can study the evolution of instrumentation errors during transients as well as normal operation.V. PROTECTIVE RELAY MODELINGToday, all new relays are numerical relays. These types of relays can be easily modeled within the virtual power system. Consider, for example, a directional relay. The operation of this relay is based on the phase angle between the polarizing voltage and the current. Modeling of this relay then requires that the phase angle between the polarizing voltage and the current be computed. For this purpose, as the power system simulation progresses, the relay model retrieves the instantaneous values of the polarizing voltage and the current. A Fourier transform is applied to the retrieved data (a running time Fourier transform over a user-specified time window). The result will be the phasors of the polarizing voltage and current from which the phase angles are retrieved. The directional element of the relay will trip if the phase angle difference is within the operatingregion. It should be also self understood that if the relay to be modeled be also included in the model.It is important that students be also involved in the design of numerical relays. A typical semester project is to define the functionality of a specific relay and a set of test cases. The student assignment is to develop the code that will mimic the operation of the relay and demonstrate its correct operation for the test cases.The new technology of the virtual power system offers another more practical way to model relays. The virtual power system uses object-oriented programming. As such, it is an open architecture and can accept dynamic link libraries of third parties. A natural extension of the work reported in this paper is to use this feature to interface with commercially available digital “relays.” The word “relay” is in quotation marks to indicate that the relay is simply a digital program that takes inputs of voltages and currents, performs an analysis of these data, applies logic, and issues a decision. This program is an object and can be converted into a dynamic link library. If this DLL is “linked” with the virtual power system, in the sense that the inputs come from the virtual power system, then the specific relay can be evaluated within the virtual environment. The technology for this approach is presently available. Yet, our experience is that relay manufacturers are not presently perceptive in making their “relay” objects available as DLLs that can be interfaced with third-party software.VI. APPLICATIONSThe described virtual environment used in a variety of educationalassignments. The possible uses are only limited by the imagination of the educator. In this section, we describe a small number of educational application examples.Figs. 3 and 4 illustrate an exercise of studying instrumentation channel performance. Fig. 3 illustrates an example integrated model of a simple power system and the model of an instrumentation channel (voltage). The instrumentation channel consists of a PT, a length of control cable, an attenuator, and an AD converter (Fig. 3 illustrates the icons of these components and their interconnection). Fig. 4 illustrates two waveforms: the voltage of phase A of the power system when it is experiencing a fault and the error of the instrumentation channel. The upper part of the figure illustrates the actual voltage of Phase A and the output of the instrumentation channel (multiplied by the nominal transformation ratio). The two traces are quite close. The lower part of the figure illustrates the error between the two waveforms of the upper part of the figure. The two curves illustrate the normalized error at the input of the AD converter and at the output of the AD converter. The figure is self-explanatory and a substantial error occurs during the transient of the fault. When the transients subside, the error of the instrumentation channel is relatively small. The intention of this exercise is to study the effects of different parameters of the instrumentation channel.For example, the students can change the length of the control cable and observe the impact on the error. Or in case of a current channel, they can observe the effects of CT saturation on the error of the instrumentation channel, etc.Fig. 5 illustrates the basics of an example application of the virtualpower system for visualization and animation of a modified impedance relay. The example system consists of a generator, a transmission line, a step-down transformer, a passive electric load (constant impedance load), an induction motor, and a mechanical load of the motor (fan). A modified distance relay (mho relay) monitors the transmission line. The operation of thi s relay is based on the apparent impedance that the relay “sees” and the trajectory of this impedance.The visualization object of this relay displays what the relay “sees” during a disturbance in the system and superimposes this information on the relay settings. Typical examples are illustrated in Figs. 6 and 7. The relay monitors the three-phase voltages and currents at the point of its application. The animation model retrieves the information that the relay monitors from the simulator at each time step. Subsequently, it computes the phasors of the voltages and currents as well as the sequence components of these voltages and currents. Fig. 6 illustrates a 2-D visualization of the operation of this relay over a period that encompasses a combined event of an induction motor startup followed by a single-phase fault on the shows the voltages and currents “seen” by the relay(the snapshot is after the fault cleared). The graph also shows the trajectory (” by the relay. The graph shows the trajectory “seen” o ver a user-specified time interval preceding present time. The impedance trajectory is superimposed on the trip characteristics of this relay. In this case, the impedance trajectory does not visit the trip “region” of the relay.Fig. 7 provides the recorded impedance trajectory for the combined event of an induction motor startup followed by a three-phase fault nearthe low-voltage bus of the transformer. The impedance trajectory is superimposed on the trip characteristics of this relay. In this case, the i mpedance trajectory does visit the trip “region” of the relay. This example can be extended to more advanced topics. For example, the animated display may also include stability limits for the “swing” of the generator. For this purpose, the stability limits for the particular condition must be computed and displayed.This exercise can be the topic of a term project.Another important protective relaying example is the differential relay. In this example, we present the animated operation of a differential relay scheme for a delta-wye connected transformer with tap changing under load. The example system is shown in Fig. 8. It consists of an equivalent source, a transmission line, a 30-MVA delta-wye connected transformer, a distribution line, and an electric load. A transformer differential relay Fig.7. Animation of a mho relay for a three phase fault on the 13.8-kV bus. is protecting the transformer. The differential relay of a differential relay visualization is shown in Fig. 9 based on the electromechanical equivalent relay. Note that the 2-D visualization shows the “operating” coils and “restraining” coils and the currents that flow in these coils at any instant of time. Instantaneous values, rms values, and phasor displays are displayed. Fig. 9 illustrates one snapshot of the system. In reality, as the system operation progresses, this figure is continuously updated, providing an animation effect. The system may operate under steady-state or under transient conditions. The effects of tap changing on the operation of the relay are demonstrated. The importance of this animation module is that one can study the effects of various parameters and phenomena on theoperation of the relay. Examples are: a) effects of tap setting. The differential relay settings are typically selected for the nominal tap setting. As the tap setting changes under load, the current in the operating coil changes and may be nonzero even under normal operating conditions. It is very easy to change the tap setting andobserve the operation of the relay in an animated fashion. It is also easy to observe the operation of the relay during a through fault for different values of tap settings. Thus, this tool is very useful in determining the optimal level of percent restraint for the relay. b) effects of inrush currents. One can perform energization simulations of the transformer by various types of breaker-closing schemes. Since the transformer model includes the nonlinear magnetization model of the transformer core, the magnetization inrush currents will appear in the terminals of the transformer and, therefore, in the differential relay. The display of Fig. 9 provides a full picture of the evolution of the electric currents. One can study the effects of inrush currents by bypassing the even study these phenomena indepth and in very short time with the aid of animation and visualization methods.The virtual power system also used for testing of physical relays. This application is quite simple. The virtual power system COMTRADE format. Then, the COMTRADE file is fed into commercial equipment that generates the actual voltages and currents and feeds them into the physical relays. The actual response of the relays is then observed. This application was performed on the premises of a utility with limited access to students.Recently, a major relay manufacturer (SEL) the process of setting upthe laboratory for routine use of this function by students. There are numerous other applications of the proposed virtual power system. The pedagogical objective is to instill a deep understanding of protective relaying concepts and problems in the very short time of one semester. The effectiveness of the proposed approach increases as new examples are generated and stored in the database.Aclassical example that demonstrates the effectiveness of the virtual power system is the issue of sympathetic tripping. Usually, this topic requires several lectures and long examples. With the virtual power system, one can very thoroughly teach the concept of sympathetic tripping within onelecture. For example, a simple system with mutually coupled lines can be prepared, with relays at the ends of all lines. Then with a fault in one line, the relays of the be visualized and animated. The students can observe that the relays of the another line. And more important, the students can make changes to the designs of the lines and observe the relative effect of design parameters on induced voltages and currents, etc.VII. CONCLUSIONThis paper for visualization and animation of protective relaying. The virtual power system the instruction of protective relaying courses. It is also an excellent tool for assigning term projects on various aspects of protective relaying. One important feature of the tool is that the user can apply disturbances to the system while the system operates (i.e., faults, load shedding, motor start-up, etc.). The response of the relays is instantaneously observed. The paper a multitasking environment.The paper and animation of instrumentation channel error, b)impedance relay, and c) a transformer differential relay. From these examples, it is clear that virtual laboratories can be quite beneficial from the educational point of view as they can provide insight of the system under study that are impossible in a physical laboratory. In addition, the virtual power system is valuable for testing commercially available digital relays with appropriate interfaces between the virtual power system and the numerical relay software.The effectiveness of this approach assessed informally with discussions with students and evaluation of the term projects. The response is positive and enthusiastic (for example, two of the term project reports were over 100 pages long and the content reflected an excellent understanding of protective relaying concepts and technology). We plan to conduct formal evaluation of the approach by the students.The tool is continuously under development as additional relay functions and animation and visualization objects of various protective relay functions are being developed. This task is open ended because of the plethora of existing power system relaying devices and possible ways to visualize and animate their functions. There is also a multiplicity of term projects that can be designed and assigned to students with the virtual power system as the basic tool. We also plan to make this tool available to power educators. Presently, the tool is posted on the course web site, when the course is offered. The web site is terminated when the course is completed. In the next offering of the course, the web site will be made permanent and accessible to power educators.附录1 外文资料译文。
住宅小区配电设计外文文献翻译中英文
外文文献翻译(含：英文原文及中文译文)译文字数：3700多字文献出处：J Ehnberg. Power of Community Distribution to Design[J] Value Engineering, 2016, 2(3):14-21英文原文Power of Community Distribution to DesignJ EhnbergABSTRACTThe 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, 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 onpower net and the loss brought from power-off.KEYWORDS: power supply and distribution, power distribution reliability , reactive compensation, load distributionIn general, major changes to the building include: high voltage and low voltage distribution systems, transformers, and backup power systems. Power systems include power distribution and control, indoor and outdoor lighting systems include all types of lighting, and lightning protection systems include intrusion protection, lightning sensors, grounding, equipotential bonding, and local equipotential bonding. Auxiliary equipotential bonding. In just 20 years, the system has undergone enormous changes in the face of technology and products. Many design ideas have also changed dramatically. Switchgear, such as the first circuit-breaker oil circuit breaker in a high-voltage system, and the subsequent development of an oil circuit breaker, are not only large in size but generally contain oil. Due to the large size of the switchgear, we must also establish a separate equipment room that occupies a large amount of floor area. Vacuum circuit breakers and sulfur hexafluoride circuit breakers are not only small in size, but also have a large short-circuit capacity. The size of the housing is much larger than that of the original cabinets, and the circuit breakers do not have any oil and the fire performance is greatly improved. And circuit breakers and other low-voltage devices are in one room, which saves space and is easy tomanage. In the past, large-capacity low-voltage circuit breakers gradually increased the capacity of the short-circuit current, gradually reduced the scale, and became more stable, making the system safer and more reliable, which facilitated the design. Towards the development of intelligent low-voltage circuit breakers, various parameters of the circuit breaker can be controlled by the bus industry and the signals are transmitted directly to the computer.The appearance of dry-type transformers has brought great convenience to the electrical design of buildings because there is no possibility of leakage of transformer oil and fire so that it can be easily installed in the building itself and even directly into the load center. It also eliminates the transformer's demand for oil and can use dry-type transformers when building large-capacity equipment. Four Taiwanese 2500kV A dry-type transformers have been used in actual engineering design.In terms of using emergency generators, it is much more advanced than in the past in terms of performance and size. In addition to using diesel generators; emergency lighting uses EPS standby power; devices that interrupt power within a millisecond can use UPS.The control of electrical equipment varies from the control of a single component to the control of relays. In addition to the smaller size of the various components for better performance, the specification of thecontrol box is also reduced. Because digital technology is more used in control to achieve the best control status to control the equipment. Further improve the effect of energy conservation.The 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 international advanced electric knowledge, the dissertation introduces the research hotspot for present electric power syetem 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 andcurrent 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 andsocial 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 modes about 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 onpower 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 guidelinefor the programming design of the lOkV electric distribution net and building up a solid net, reasonable layout, qualified safe and efficiently-worked electric distribution net.Auto-Tune SequenceThe auto-tuning sequence begins after the hysteresis and deviation values have been determined. The tuning process begins when the initial output step is applied to the loop output.This change in output value should cause a corresponding change in the value of the process variable. When the output change drives the PV away from setpoint far enough to exceed the hysteresis boundary a zero-crossing event is detected by the auto-tuner. Upon each zero crossing event the auto-tuner drives the output in the opposite direction.The tuner continues to sample the PV and waits for the next zero crossing event. A total of twelve zero-crossings are required to complete the sequence. The magnitude of the observed peak-to-peak PV values (peak error) and the rate at which zero-crossings occur are directly related to the dynamics of the process. Early in the auto-tuning process, the output step value is proportionally adjusted once to induce subsequent peak-to-peak swings of the PV to more closely match the desired deviation amount. Once the adjustment is made, the new output step amount is written into the Actual Step Size field (ASTEP) of the loop table. The auto-tuning sequence will be terminated with an error, if thetime between zero crossings exceeds the zero crossing watchdog interval time. The default value for the zero crossing watchdog interval time is two hours.中文译文住宅小区配电设计J Ehnberg摘要电力系统的基本功能是向客户输送电力。
论文某小区供配电系统设计本科生毕业设计论文[精选整理].doc
![论文某小区供配电系统设计本科生毕业设计论文[精选整理].doc](https://img.taocdn.com/s3/m/aa8e0448a21614791611280f.png)
本科生毕业设计（论文）某小区供配电系统设计Design for the Power Supply and distribution systemof a residence community总计： 36 页表格： 10 个插图： 9 幅南阳理工学院本科毕业设计（论文）某小区供配电系统设计Design for the Power Supply and distribution systemof a residence community学院：电子与电气工程学院专业：电气工程及其自动化学生姓名：学号：指导教师（职称）：评阅教师：完成日期：南阳理工学院Nanyang Institute of Technology毕业设计（论文）原创性声明和使用授权说明原创性声明本人郑重承诺：所呈交的毕业设计（论文），是我个人在指导教师的指导下进行的研究工作及取得的成果。
尽我所知，除文中特别加以标注和致谢的地方外，不包含其他人或组织已经发表或公布过的研究成果，也不包含我为获得及其它教育机构的学位或学历而使用过的材料。
对本研究提供过帮助和做出过贡献的个人或集体，均已在文中作了明确的说明并表示了谢意。
作者签名：日期：指导教师签名：日期：使用授权说明本人完全了解大学关于收集、保存、使用毕业设计（论文）的规定，即：按照学校要求提交毕业设计（论文）的印刷本和电子版本；学校有权保存毕业设计（论文）的印刷本和电子版，并提供目录检索与阅览服务；学校可以采用影印、缩印、数字化或其它复制手段保存论文；在不以赢利为目的前提下，学校可以公布论文的部分或全部内容。
作者签名：日期：学位论文原创性声明本人郑重声明：所呈交的论文是本人在导师的指导下独立进行研究所取得的研究成果。
除了文中特别加以标注引用的内容外，本论文不包含任何其他个人或集体已经发表或撰写的成果作品。
对本文的研究做出重要贡献的个人和集体，均已在文中以明确方式标明。
本人完全意识到本声明的法律后果由本人承担。
毕业设计英文文献翻译(电力方向附带中文)
毕业设计英文文献翻译(电力方向附带中文)大学毕业设计英文文献翻译,关于电力系统方向,电力谐波!绝对原创!HarmonicsService reliability and quality of power have become growing concerns for many facility managers, especially with the increasing sensitivity of electronic equipment and automated controls. There are several types of voltage fluctuations that can cause problems, including surges and spikes, sags, harmonic distortion, and momentary disruptions. Harmonics can cause sensitive equipment to malfunction and other problems, including overheating of transformers and wiring, nuisance breaker trips, and reduced power factor.What Are Harmonics?Harmonics are voltage and current frequencies riding on top of the normal sinusoidal voltage and current waveforms. Usually these harmonic frequencies are in multiples of the fundamental frequency, which is 60 hertz (Hz) in the US and Canada. The mostcommon source of harmonic distortion is electronic equipment using switch-mode power supplies, such as computers, adjustable-speed drives, and high-efficiency electronic light ballasts.Harmonics are created by these Dswitching loads‖ (also called “nonlinear loads,‖ because current does not vary smoothly with voltage as it does with simple resistive and reactive loads): Each time the current is switched on and off, a current pulse is created. The resulting pulsed waveform is made up of a spectrum of harmonic frequencies, including the 60 Hz fundamental and multiples of it. This voltage distortion typically results from distortion in the current reacting with system impedance. (Impedance is a measure of the total opposi tion―resistance, capacitance, and inductance―to the flow of an alternating current.) The higher-frequency waveforms, collectively referred to as total harmonic distortion (THD), perform no useful work and can be asignificant nuisance.Harmonic waveforms are characterized by their amplitude and harmonic number. In the U.S. and Canada, the third harmonic is 180 Hz―or 3 x 60 Hz―and the fifth harmonic is 300 Hz (5 x 60Hz). The third harmonic (and multiples of it) is the largest problem in circuits with single-phase loads such as computers and fax machines. Figure 1 shows how the 60-Hz alternating current (AC) voltage waveform changes when harmonics are added.大学毕业设计英文文献翻译,关于电力系统方向,电力谐波!绝对原创!The Problem with HarmonicsAny distribution circuit serving modern electronic devices will contain some degree of harmonic frequencies. The harmonics do not always cause problems, but the greater the power drawn by these modern devices or other nonlinear loads, the greater the level of voltage distortion. Potential problems (or symptoms of problems) attributed to harmonics include:■ Malfunction of sensitive equipment■ Random tripping of circuit breakers■ Flickering lights■ Very high neutral currents■ Overheated phase conductors, panels, and transformers ■ Premature failure of transformers and uninterruptible power supplies (UPSs)■ Reduced power factor■ Reduced system capacity (because harmonics create additional heat, transformers and otherdistribution equipment cannot carry full rated load)Identifying the ProblemWithout obvious symptoms such as nuisance breaker trips or overheated transformers, how do you determine whether harmonic current or voltages are a cause for concern? Here are several suggestions for simple, inexpensive measurements that a facility manager or staff electrician could take, starting at the outlet and moving upstream:■ Measure the peak and root mean square (RMS) voltage at a sample of receptacles. The Dcrest factor‖ is the ra tio of peak to RMS voltage. For a perfectly sinusoidal voltage, the crest factor will be 1.4. Low crest factor is a clear indicator of the presence of harmonics. Note that these measurements must be performed with a Dtrue RMS‖ meter―one that doesn‘t assume a perfectly sinusoidal waveform.■ Inspect distribution panels. Remove panel covers and visually inspect components for signs of overheating, including discolored or receded insulation or discoloration of terminal screws. If you see any of these symptoms, check that connectionsare tight (since loose connections could also cause overheating), and compare currents in all conductors to their ratings.■ Measure phase and neutral currents at the transformer secondary with clamp-on current probes. If no harmonics are being generated, the neutral current of a three-phase distribution system carries only the imbalance of the phase currents. In a well-balanced three-phase distribution system, phase currents will be very similar, and current in the neutral conductor should be much lower than phase current and far below its rated current capacity. If phase currents are similar and neutral current exceeds their imbalance by a wide margin, harmonics are present. If neutral current is above 70 percent of the cond uctor‘s rated capacity, you need to mitigate the problem.■Compare transformer temperature and loading with nameplate temperature rise and capacity ratings. Even lightly loaded transformers can overheat if harmonic current is high. A transformer that is near or over its rated temperature rise but is loaded well below its rated capacity is a clear sign that harmonics are at work. (Many transformers have built-in temperature gauges. If yours does not, infrared thermography can be used to detect overheating.)大学毕业设计英文文献翻译,关于电力系统方向,电力谐波!绝对原创!In addition to these simple measurements, many power-monitoring devices are now commercially available from a variety of manufacturers to measure and record harmonic levels. These instruments provide detailed information on THD, as well as on the intensity of individual harmonic frequencies. After taking the appropriate measurements to determine whether you have high levels of harmonics and, if so, to find the source, you will be well-positioned to choose the best solution.Solutions to Harmonics ProblemsThe best way to deal with harmonics problems is through prevention: choosing equipment and installation practices that minimize the level of harmonics in any one circuit or portion of a facility. Many power quality problems, including those resulting from harmonics, occur when new equipment is haphazardly added to older systems. However, even within existing facilities, the problems can often be solved with simple solutions such as fixing poor or nonexistent grounding on individual equipment or the facility as a whole, moving a few loads between branch circuits, or adding additional circuits to help isolate the sensitiveequipment from what is causing the harmonic distortion. If the problems cannot be solved by these simple measures, there are two basic choices: to reinforce the distribution system to withstand the harmonics or to install devices to attenuate or remove the harmonics. Reinforcing the distribution system means installing double-size neutral wires or installing separate neutral wires for each phase, and/or installing oversized or Krated transformers, which allow for more heat dissipation. There are also harmonic-rated circuit breakers and panels, which are designed to prevent overheating due to harmonics. This option is generally more suited to new facilities, because the costs of retrofitting an existing facility in this way could be significant. Strategies for attenuating harmonics, from cheap to more expensive, include passive harmonic filters, isolation transformers, harmonic mitigating transformers (HMTs), the Harmonic Suppression System (HSS) from Harmonics Ltd., and active filters(Table 1).Passive filters (also called traps) include devices that provide low-impedance paths to divert harmonics to ground and devices that create a higher-impedance path to discourage the flow of harmonics. Both of these devices, by necessity, change theimpedance characteristics of the circuits into which they are inserted. Another weakness of passive harmonic technologies is that, as their name implies, they cannot adapt to changes in the electrical systems in which they operate. This means that changes to the electrical system (for example, the addition or removal of power factorCcorrection capacitors or the addition of more nonlinear loads) could cause them to be overloaded or to create Dresonances‖ that could actually amplify, rather than diminish, harmonics.Active harmonic filters, in contrast, continuously adjust their behavior in response to the harmonic current content of the monitored circuit, and they will not cause resonance. Like an automatic transmission in a car, active filters are designed to accommodate a full range of expected operating conditions upon installation, without requiring further adjustments by the operator.Isolation transformers are filtering devices that segregate harmonics in the circuit in which they are created, protecting upstream equipment from the effects of harmonics. These transformers do not remove the problem in the circuit generating the harmonics, but they can prevent the harmonics from affecting more sensitive equipment elsewhere within the facility.大学毕业设计英文文献翻译,关于电力系统方向,电力谐波!绝对原创!Harmonic mitigating transformers actually do relieve problematic harmonics. HMTs can be quite cost-effective in the right application, because they can both improve reliability and reduce energy costs. The right application includes transformers that are heavily or moderately loaded and where high levels of harmonic currents are present. In addition, HMTs are very effective in supporting critical loads that are backed up by a UPS. UPSs and backup generators tend to have high impedance, which results in high voltage distortion under nonlinear loading. Because of this, equipment that operates flawlessly when supplied by utility power may malfunction when the backup system engages during a utility outage. Note that some of these power systems have output filters (either passive or active) to control harmonic levels. The presence or absence of such filters should be determined before adding an HMT.The Harmonics Ltd. Harmonic Suppression System is a unique solution for single-phase loads that is designed to suppress the third harmonic. An HSS is generally more expensive than an HMT, but it is designed to attenuate the harmonicsproblems throughout the entire distribution system, not just upstream of the transformer. The types of facilities that present the best opportunities for HSS installation are those that place a very high premium on power quality and reliability, such as server farms, radio and television broadcast studios, and hospitals. (See .) Economic EvaluationEvaluating the life-cycle costs and effectiveness of harmonics mitigation technologies can be ve ry challenging―beyond the expertise of most industrial facility managers. After performing the proper measurement and analysis of the harmonics problem, this type of evaluation requires an analysis of the costs of the harmonics problem (downtime of sensitive equipment, reduced power factor, energy losses or potential energy savings) and the costs of the solutions. A good place to start in performing this type of analysis is to ask your local utility or electricity provider for assistance. Many utilities offer their own power quality mitigation services or can refer you to outside power quality service providers.Additional ResourcesInstitute of Electrical and Electronics Engineers (IEEE),Standard 519-1992, DIEEE大学毕业设计英文文献翻译,关于电力系统方向,电力谐波!绝对原创!Recommended Practices and Requirements for Harmonic Control in Electric Power Systems‖ (1992), available at .Relationship between harmonics and symmetrical componentsAbstract New terminology is introduced to make clear the relationship between harmonics and symmetrical components. Three-phase sets are classified in terms of symmetrical sets and asymmetrical sets. Subclasses are introduced with the names symmetrical balanced sets, symmetrical unbalanced sets, asymmetrical balanced sets and asymmetrical unbalanced sets to show that a threephase set can resolve to either one, two or three symmetrical component sets. The results from four case studies show that these subclasses and their resolution to symmetrical component sets improve understanding of harmonic analysis of systems having balanced and unbalanced harmonic sources and loads.Keywords asymmetrical sets; harmonic flows; harmonic sources; symmetrical component sets; symmetrical sets Any periodic wave shape can be broken down into oranalysed as a fundamentalwave and a series of harmonics.Three-phase harmonic analysis requires a clear understanding of the relationship between symmetrical component injections from harmonic sources (e.g. adjustable speed drives, ASDs) and their relationship to harmonic flows (symmetrical components) arising from the application of a harmonic source to a linear system.Alimited number of references contain brief information concerning harmonics and symmetrical components. Reference 1, provides a paragraph on this topic and uses the heading Relationship between Harmonics and Symmetrical Components‘.It includes a table that is supported by a brief explanatory paragraph. The table expresses harmonics in terms of positive, negative and zero sequences. It states that these sequences are for harmonics in balanced three-phase systems. The heading refers to symmetrical components while the content refers to balanced three-phase systems. Herein lies the anomaly. Classically, symmetrical components (especially ero sequence) are only applied in unbalanced systems. The following questions rose after reading the Ref. 1 paragraph.(a)Do symmetrical components (especially zero sequence), in the classical sense,apply in balanced as well as unbalanced non-sinusoidal systems and is this abreak from tradition?(b)What do the terms, symmetrical, asymmetrical, balanced, unbalanced andsymmetrical components mean?(c)What are the conditions under which a system must operate so that harmonicsresolve to positive, negative and zero sequences and is the table given inRef. 1 correct?The terminology used is found inadequate for describing non-sinusoidal systems.There is thus a need to introduce a three-phase terminology that will show the relationship and make the comparison between injections (currents) and harmonic flows (voltages and currents) meaningful.References 3 provides the basis for the solution by providing definitions for threephase sets‘, symmetrical sets‘an d symmetricalcomponent sets‘.The purpose of this paper is to introduce an approach to harmonic analysis大学毕业设计英文文献翻译,关于电力系统方向,电力谐波!绝对原创!based on the classification of three-phase sets and to make to comparison between injections from harmonic sources and corresponding harmonic flows quantifiable by expressing the results in terms of the number of symmetrical component sets found.Harmonic flows and their resolution to symmetrical components depends upon the magnitudes and phase sequences of the injections from a harmonic source, on the system‘s sequence impedances, on three- and four-wire connections and on whether the customer‘s linear load on the system is balanced or unbalanced. Therefore, what is injected in terms of symmetrical component sets by a harmonic source is not necessarily received by the system, i.e. the harmonic flows may resolve to one, two or three symmetrical component sets and this depends upon the type of three-phase set found. Therefore, any three-phase harmonic may be partially made up of any of thesymmetrical component sets.Four case studies are reported and they show a novel method for teaching the flow of power system harmonics. It is important to use case studies as part of one‘s teaching as they link learning to concepts and improve understanding. They show how the method of symmetrical components can be extended to a system‘s response to harmonic flows. When taught as a group, the four case studies improve cognitive skills by showing that the symmetrical component responses under unbalanced situations are different to the balanced state.IEEE __TIONS ON POWER __NICS VOL.19,NO.3,__年大学毕业设计英文文献翻译,关于电力系统方向,电力谐波!绝对原创!谐波服务的可靠性和电能质量已成为越来越多设施经理的关注，尤其是随着电子设备和自动化控制灵敏度提高了很多。
电气专业毕业设计外文翻译
附录AA few examples will refresh your memory about the content of Chapter 8 and thegeneral approach to a nodal-analysis solution.EXAMPLE 17.12 Determine the voltage across the inductor for the network of Fig.Solution:Steps 1 and 2 are as ndicated in Fig.17.22.Step 3:Note Fig.17.23 for the application of Kirchhoff ’s current law to node V1:Fig.17.22 Fig.17.23∑Ii=∑I0 0=I1+I2+I3V1-E/Z1+(V1/Z2)+(V1-V2)/Z3=0Rearranging terms: V1[1/Z1+1/Z2+1/Z3]-V2[1/Z3]=E1/Z1 (17.1)Note Fig.17.24 for the application of Kirchhoff ’s current law to node V2:0=I3+I4+IV2-V1/Z3+V2/Z4+I=0Rearranging terms: V2[1/Z3+1/Z4]-V1[1/Z3]=-I (17.2)Fig.17.24Grouping equations: V1[1/Z1+1/Z2+1/Z3]-V2[1/Z3]=E1/Z1V1[1/Z3]-V2[1/Z3+1/Z4] =I1/Z1+1/Z2+1/Z3=1/0.5k Ω+1/10 k Ω+1/2k Ω=2.5mS ∠-2.29°1/Z3+1/Z4=1/2k Ω+1/-5k Ω=0.539mS ∠21.80°and V1[2.5ms ∠-2.29°]-V2[0.5mS ∠0°]=24m Α∠0°V1[0.5mS ∠0°]-V2[0.539mS ∠21.80°]=4m Α∠0°with 24m Α∠0° -0.5mS ∠0°4mΑ∠0°-0.539mS∠21.80°V1= 2.5ms∠-2.29°-0.5mS∠0°0.5mS∠0°-0.539mS∠21.80°=(24mΑ∠0°)(-0.539mS∠21.80°)+(0.5mS∠0°)(4mΑ∠0°)/[(2.5ms∠-2.29°)(-0.539mS∠21.80°)+(0.5mS∠0°)(0.5mS∠0°)]=-10.01ν-j4.81ν/-1.021-j0.45=11.106ν∠-154.33°/1.116∠-156.21°V1=9.95∠1.88°MathCad The length and complexity of the above mathematical development strongly suggest the use of an alternative approach such as MathCad.Note in MathCad 17.2 that the equations are entered in the same format as Eqs.(17.1) and (17.2).Both V1 and V2 were generated,but because only V1 was asked for,it was the only solution converted to the polar form.In the lower solution the complexity was significantly reduced by simply recognizing that the current is in milliamperes and the impedances in kilohms. The result will then be in volts.K :=10³m :=0.01 rad :=1V1 :=1+j V2 :=1+j deg :=π/180GivenV1·[1/5·k+1/10j·k+1/2·k]-V2·1/2·k≈24·mV1·[1/2·k]-V2[1/2·k+1/-5j·k]≈4·mFind(V1,V2)= 9.944 +0.319j Volts1.786 -0.396j VoltsV1 :=9.944+0.319j V1 =9.949 arg(V1)=1.837·degRecognizing that current in mA results ehen Z is in kilohmns,an alternative format follows:GivenV1·[1/5+1/10j+1/2]-V2·1/2≈24V1·1/2-V2[1/2+1/-5j]≈4Find(V1,V2)= 9.944 +0.319j Volts1.786 -0.396j VoltsV1 :=9.944+0.319j V1 =9.949 arg(V1)=1.837·degMATHCAD 17.2Dependent Current Sources For dependent current sources,the procedure is modified as follows:Steps 1 and 2 are the same as those applied for independent sources.Step 3 is modified as follows:Treat each dependent current source like an independent source when Kirchhoff’s current law applied to each defined node.However,once the equations are established,substitute the equation for the controlling quantity to ensure that the unknowns are limited solely to the chosen nodal voltages.1.Step 4 is as before.EXAMPLE 17.13 Write the nodal equations for the network of Fig.17.25 having a dependent current source.Solution: Steps 1 and 2 are as defined in Fig.17.25.Fig.17.25.Step 3: At node V1, I=I1+I2V1/Z1+V1-V2/Z2-I=0and V1[1/Z1+1/Z2]-V2[1/Z2]=IAt node V2, I2+I3+ΚI=0V2-V1/Z2+V2/Z3+Κ[V1-V2/Z2]=0and V1[1-Κ/Z2]-V2[1-Κ/Z2+1/Z3]=0resulting in two equations and two unknowns.Independent Voltage Sources between Assigned Nodes For independent voltage sources between assigned nodes,the procedure is modified as follows:1.Steps 1 and 2 are the same as those applied for independent sources.2.Step 3 is modefied as follows:Treat each source betwwen defined nodes as ashort circuit(recall the supernode classification of Chapter 8),and write the nodal equations for each remaining independent node.Then relate the chosen nodal voltages to the independent voltage source to ensure that the unknowns of the ginal equations are limited solely to the nodal voltages.3.Step 4 is as before.EXAMPLE 17.14 Write the nodal equations for the network of Fig.17.26 having an independent source between two assigned nodes.Solution: Steps 1 and 2 defined in Fig.17.26.Step 3:Replacing the independent source E with a short-circuit equivalent results in a supernode that will generate the following equation when Kirchhoff’s current law is applied to node V1: I1=V1/Z1+V2/Z2+I2with V2-V1=EFig.17.26.and we have two equationsand two unknowns.Dependent Voltage Source between Defined Nodes For dependent voltage sources between defined nodes,the procedure is modified as follows:1.Steps 1 and 2 are the same as those applied for independent voltage sources.2.Step 3 is modified as follows:The procedure is essentially the same as thatapplied for independent voltage sources,except now the dependent sourcess having to be defined in terms of the chosen nodal voltage to ensure that the final equations have only nodal voltage as their unknown quantities.3.Step 4 is as before.EXAMPLE 17.15Write the nodal equations for the network of Fig.17.27 having a dependent voltage source between two defined nodes.Solution: Steps 1 and 2 are defined in Fig.17.27.Fig.17.27.Step 3:Replacing the dependent source μVx with a short-circuit equivalent will result in the following equation when Kirchhoff's current law is applied at node V1:I=I1+I2V1/Z1+(V1-V2)/Z2-I=0and V2=μVx=μ[V1-V2]or V2=μV1/1+μresulting in two equations and two unknowns.Note that because the impedance Z3 is in parallelwith a voltage source,it does not appear in the analysis.It will,however,affect the current through the dependent voltage source.Format ApproachA close examination of Eqs.(17.1) and (17.2) in Example 17.12 will reveal thatthey are the same equations that would have been obtained using the format approach introduce in Chapter 8.Recall that the approach required that the voltage source first be converted to a current source,but the writing of the equations was quite direct and minimized any chances of an error due to lost sign or missing term.The sequence of steps required to apply the format approach is the following:1.Choose a reference node and assign a subscripted voltage lable to the(N-1)remaining independent nodes of the network.2.The number of equations required for a complete solution is equal to the numberof subcripted voltages(N-1).Column 1 of each equation is formed by summing the admittances tied to the node of interest and multiplying the result by that subscripted nodal voltage.3.The mutual terms are always subtracted from the terms of the first column.It ispossible to have more than one mutual term if the nodal voltage of interest has an element in common with more than one other nodal voltage.Each mutual term is product of the mutual admittance and the other nodal voltage tied to that admittance.4.The column to the right of the equality sign is the algebraic sum of the currentsources tied to the node of interest.A current source is assigned a positive sign if it supplies current to a node,and a negative sign if it draws current from the node. Solve resulting simultaneous equations for the desired nodal voltages.The comments offered for mesh analysis regarding independent and dependent sources apply here also.EXAMPLE 17.16Using the format approach to nodal analysis,find the voltage across the 4-Ωresistor in Fig.17.28.Fig.17.28.Solution: Choosing nodes(Fig.17.29) and writing the nodal equations,we have Z1=R=4ΩZ2=jXl=j5ΩZ3=-jXc=-j2ΩFig.17.29V1(Y1+Y2)-V2(Y2)=-I1V2(Y3+Y2)-V1(Y2)=+I2or V1(Y1+Y2)-V2(Y2)=-I1-V1(Y2)+V2(Y3+Y2)=+I2Y1=1/Z1 Y2=1/Z2 Y3=1/Z3Using determinants yields-I1 -Y2+I2 Y2+Y3V1 = =-(Y3+Y2)I1+I2Y2/(Y1+Y2)(Y3+Y2)-Y2Y2Y1+Y2 -Y2-Y2 Y3+Y2=-(Y3+Y2)I1+I2Y2/Y1Y3+Y2Y3+Y1Y2Substituting numerical values,we haveV1=-[(1/-j2Ω)+(1/j5Ω)]6Α∠0°+4Α∠0°(1/j5Ω)/(1/4Ω)(1/-j2Ω)+(1/j5Ω)(1/-j2Ω)+(1/4Ω)(1/j5Ω)=-(+j0.5-j0.2)6∠0°+4∠0°(-j0.2)/(1/j8)+(1/10)+(1/j20)=(-0.3∠90°)(6∠0°)+4∠0°(-j0.2)/j0.125+0.1-j0.05=-1.8∠90°+0.8∠-90°/0.1+j0.075=2.6ν∠-90°/0.125∠36.87°V1=20.80ν∠-126.87°MathCad Using MathCad and the matrix format with the admittance parameters will quickly provide a solution for V1 in Example 17.16,as shown in MathCad 17.3.Z1 :=4 Z2 :=5j Z3 :=-2j rad :=1 deg :=π/180Y := [1/Z1+1/Z2] -1/Z2 I := -6 -1/Z2 [1/Z2+1/Z3] 4I/Y= -12.48 -16.64j Volts8.32 -2.24j VoltsV1 := -12.48 -16.64j V1=20.8 arg(V1)=-126.87·degV2 := 8.32 -2.24j V2=8.616 arg(V2)=-15.068·degMATHCAD 17.3EXAMPLE 17.17 Using the format approach,write the nodal equations for the network of Fig.17.30.Fig.17.30.Solution: The circuit is redrawn in Fig.17.31,whereZ1=R1+jXl1=7Ω+j8ΩE1=20ν∠0°Z3=-jXc=-j10ΩZ2=R2+jXl2=4Ω+j5ΩI1=10Α∠20°Z4=R3=8ΩConverting the voltage source to a current source and choosing nodes,we obtain Fig.17.32.Note the “neat”appearance of the network using the subscripted impedances.Working directly with Fig.17.30would be more difficult and could produce errors.Write the nodal equations: V1(Y1+Y2+Y3)-V2(Y3)=+I2V2(Y3+Y4)-V1(Y3)=+I1Y1=1/Z1 Y2=1/Z2 Y3=1/Z3 Y4=1/Z4 which are rewritten as V1(Y1+Y2+Y3)-V2(Y3)=+I2-V1(Y3)+V2(Y3+Y4)=+I1EXAMPLE 17.18 Write the nodal equations for the network of Fig.17.33.Do not solve.Solution: Choose nodes(Fig.17.34): Z1=R1 Z2=jXl1 Z3=R2-jXc2Z4=-jXc1 Z5=R3 Z6=jXl2 and write the nodal equations: V1(Y1+Y2)-V2(Y2)=+I1V2(Y2+Y3+Y4)-V1(Y2)-V3(Y4)=-I2V3(Y4+Y5+Y6)-V2(Y4)=+I2which are rewritten as V1(Y1+Y2)-V2(Y2)+0=+I1-V1(Y2)+ V2(Y2+Y3+Y4)-V3(Y4)=-I20-V2(Y4)+V3(Y4+Y5+Y6)=+I2Y1=1/R1 Y2=1/jXl1 Y3=1/R2-jXc2 Y4=-1/jXc1 Y5=1/R3 Y6=1/jXl2Fig.17.31Note the symmetry about the diagonal for this example and those preceding it in this section.EXAMPLE 17.19Apply nodal analysis to the network of Fig.17.35.Determine the voltage Vl.Solution: In this case there is no need for a source conversion.The network is redrawn in Fig.17.36 with the chosen nodal voltage and subscripted impedances.Apply the format approach: Y1=1/Z1=1/4kΩ=0.25mS∠0°= G1∠0°Y2=1/Z2=1/1kΩ=1mS∠0°= G1∠0°Y3=1/Z3=1/2kΩ∠90°=0.5mS∠-90°=-j0.5mS=-jBlV1: (Y1+Y2+Y3)V1=-100Iand V1=-100I/Y1+Y2+Y3=-100I/0.25mS+1mS-j0.5mS=-100×10³I/1.25-j0.5=-100×10³I/1.3463∠-21.80°=-74.28×10³I∠21.80°=-74.28×10³I(Vi/1kΩ)∠21.80°V1=Vl=-(74.28Vi)V∠21.80°17.6 BRIDGE NETWORKS(ac)The basic bridge figuration was discussed in some detali in Section 8.11 for dc networks.We now continue to examine bridge networks by considering those that have reactive components and a sinusoidal ac voltage or current applied.We will first analyze various familiar forms of the bridge network using mesh analysis and nodal analysis(the format approach).The balance conditions will be investigated throughout the section.Apply mesh analysis to the network of Fig.17.37.The network is redrawn in Fig.17.38,where Z1=1/Y1=1/G1+jBc=G1/(G1²+Bc ²)-jBc/( G1²+Bc²)Z2=R2 Z3=R3 Z4=R4+jXl Z5=R5Applying the format approach: (Z1+Z3)I1-(Z1)I2-(Z3)I3=EFig.17.32(Z1+Z2+Z5)I2-(Z1)I1-(Z5)I3=0(Z3+Z4+Z5)I3-(Z3)I1-(Z5)I2=0which are rewritten as (Z1+Z3)I1-(Z1)I2-(Z3)I3=E-(Z1)I1+(Z1+Z2+Z5)I2-(Z5)I3=0-(Z3)I1-(Z5)I2+(Z3+Z4+Z5)I3=0Note the symmetry about the diagonal of the above equations.For balabce,Iz5=0Α,andIz5=I2-I3=0From the above equations,Z1+Z3 E -Z3-Z1 0 -Z5-Z3 0 (Z3+Z4+Z5)I2==E(Z1Z3+Z1Z4+Z1Z5+Z3Z5)/ΔZ1+Z3 -Z1 -Z3-Z1 (Z1+Z2+Z5) -Z5-Z3 -Z5 (Z3+Z4+Z5)where Δsignifies the determinant of the denominator(or coefficients).Similarly,I3=E(Z1Z3+Z3Z2+Z1Z5+Z3Z5)/Δand Iz5=I2-I3=E(Z1Z4-Z3Z2)/ΔFor Iz5=0,the following must be satisfied(for a finite Δnot equal to zero):Z1Z1= Iz5=0 (17.3)This condition will be analyzed in greater depth later in this section.举几个例子就刷新你对第8章的内容和一般方法一节点，分析解决内存。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
毕业设计（论文）外文参考资料及译文译文题目：Kangle community Power Of Distribution in Yandu Of yancheng盐城市盐都区康乐小区配电设计学生姓名：学号： 0804110437 专业：电气工程及其自动化所在学院：机电工程学院指导教师：职称：讲师2012 年 3 月 3日Power Of community Distribution To DesignABSTRACT: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, 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 electric knowledge, 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 andsets 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 groundingmode 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 modes about 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 withthe 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 electric distribution 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.1996.6译文:小区配电设计摘要：电力系统的基本功能是向用户输送电能。