电气专业论文资料文献综述.doc

.- 沧 州 师 范 学 院 专 业 外 语 阅 读 文 献 综 述 学 院 机械与电气工程学院 姓 名 刘昊 学 号 1414216125 专 业 电气工程及其自动化 班 级 2014级1班 2017 年 1 月 PLC技术简介与应用 摘要:随着电子计算机技术的不断发展，PLC 技术在电气化自动控制制造与研发领域中的应用变得越来越广泛，发挥着不可替代的作用。PLC 技术在电气设备自动化控制中的应用是以微软的处理器作为基础，结合了现在的计算机技术，自动控制技术，现代通讯技术等的优势，极大的扩充了 PLC 技术在电气设备自动化控制应用中的适用领域，有很强的实效性。 PLC 技术有着高灵活性、高可靠性、便捷性，和工业机器人、CAD/CAM 并称现代自动化工业的三大顶梁柱。 本文介绍何为 PLC 技术，PLC 技术在电气设备自动化控制中的优势与应用，希望能有一定的借鉴作用。 关键词:PLC 技术；电气设备；自动化控制 一.PLC 技术的概念 PLC 是英语可编程控制器 Programmable logic Controller 的缩写，以微处理器为依托，结合通信，计算机，互联网和自动控制技术开发而成的工业上的控制装置。 PLC 技术起源于 20 世纪 70 年代，被成功的运用于汽车工业中。 随着 PLC 技术运算，处理速度，控制各种功能的进步与商业化， 它在电气设备自动化中的应用领域也变得越来越广泛，形成了仪表-电器-计算机控制的一体化模式。 PLC 技术在产品中的应用与生产， 是以 DCS 集散控制系统和 FCS 总线控制系统作为主要的控制形式。 PLC 技术在将来的发展中，将不仅仅是作为一个基础系统，而是一种全分布式，开放式的控制系统。 二.PLC的结构 P L C 技术的本质是应用于工业控制的计算机技术，因此，它的硬件结构组成同大多数 计算机结构是基本一致的， 都包括有:电源、C P U( 中央处理器)、 存储器、 功能模块、 通 信模块、 输入/ 输出接口电路等等。 三.PLC的工作原理概述 第一个步骤，输入采样。在这个步骤当中，可编程控制器读取采样数据主要通过扫描的方式，然后利用输入I/O输出映像区中所对应的单元对这些数据进行存储。在数据采样被输入之后，继续执行输出刷新操作对转入用户程序。 第二个步骤，程序执行。在用户程序执行的过程中，可编程控制器对用户程序进行扫描的执行顺序总是自上而下，在扫描的过程中，其运算按照固定的顺序和路线进行，其中，扫描顺序也是由左至右，由上至下，而扫描线路则是由用户程序的各个触电构成。 第三个步骤，系统输出刷新。在这一阶段所要完成的操作是可编程控制器在执行完用户程序之后的刷新。在刷新过程中，系统的中央处理器会根据输入I/O输出映像中相应的状态和前一阶段输入的数据来进行锁存电路，再完成对其他外设的驱动。 四.PLC主要特点分析 （1）有较高的性价比，功能完备。PLC 控制器内有大量编程元件供用户使用，具有很强大且完备的控制功能，还可以利用通信联网实现集中管理但分散控制。 (2)抗干扰能力强一方面，PLC 应用了大规模的集成电路技术，在生产工艺上采用先进的抗干扰处理技术，如内部电源采取屏蔽、稳压、保护；设置独立的输入 / 输出接口电路电源等措施，从自身硬件上增强了其抗干扰能力及设备的可靠性。另一方面，通过正确选择接地地点和完善接地系统，以及采用密封、防尘、抗震的外壳进行封装，也可以起到良好的减少外界干扰的效果。通过以上措施使得 PLC 能在较为恶劣的环境中可靠的工作，并减少故障的发生率，提高了系统的可靠性。 (3)PLC 控制器具有安装方便、易维修、操作简单等优点，PLC 控制器出现故障时，其故障原因可通过其运行和故障指示装置检查出，用户在系统发生故障时，可立即采取措施更换模块等措施进行恢复，同时PLC用户界面简单明了，对于用户来说很容易掌握。 五.PLC在电力系统中的应用现状 (1)顺序控制。在火力发电系统中，其内在辅助系统的工艺流程可以分为两种方式，即开关控制和顺序控制。随着我国对能源及环境保护的重视程度越来越高，因此在火力发电行业中，其生产过程的资源节约已经成为各企业管理的目标。为达到节能减排的终极目标，必须提高该企业辅助车间的自动化控制水平。随着 PLC 控制技术的问世，在火力发电企业的辅助系统中，传统继电控制器基本被 PLC 控制系统代替，于此同时，随着科技的不断进步，PLC控制系统不仅可以对单个工艺流程进行有效控制，而且可以通过将 PLC 连接通信总 线的方式来对整个生产环节进行协调。 （2）开关量控制 断路器控制。原来的火电系统内多采用电磁型继电器为主要元件的控制器，该系统采用了大量电磁元件，因此其自身的大量触点大大降低了系统的可靠性，同时该种系统还具有接线复杂、维修困难等缺点，而近年来PLC的运用则用大量软继电器代替大量的实物元 件，因此 大大提高了其可靠性，运行人员只需进行简单 的分合闸操作，在操作过程中系统能够根据实际能否运行而给出相应的指示信号。 自动切换。为了加强供电的可靠性，备用电源 自动投人装置多年前就应用在火电企业当中，最初为手动或 自动进行供回电线路的操作，虽然该操作过程往往之需要几秒钟的时间，但对于有连续供 电要求的用户来说也是不允许的，因此，为了提高供 电的可靠性，由PLC构成 的备用电源自动投人装置应运而生，其可以通过编程来使用各种运行方式，其将采集到的一次设备 的正常运行信号作为备用电源启动或关闭的依据，由于该控制系统具有数据处理以及逻辑判断功能，因此其不仅能完成备用电源自投的操作，且其能考虑系统运行情况以及其他操作要求，同时系统本身具有很强的抗干扰能力，并具有可靠性高、接线简单、调试操作方便以及成本低等优点。 (3)闭环控制 泵类电机。火电成内泵类启动方式一般有自动启动、机旁屏手动启动以及现场控制箱手动启动几种。自动状态下泵的开机时由PLC内顺控模块根据各个泵 的累积运行时间长短来选择主备用泵；而机旁屏开启方式则是需调节现场开关的方式来启闭泵，其主备用泵则是根据人类对运行时间的比较来决定每台泵的启闭，而若要在现场对其进行操作则需将开关调至“调速器手动”档位才能实现。 六.PLC 在电气自动化中的应用前景 控制与管理功能一体化。在一台控制器上同时实现控制功能和信息处理功能，PLC 产品采用计算机信息处理技术、网络通信技术和图形显示技术，使得 PLC 系统的生产控制功能和信息管理功能融为一体，进一步提高 PLC 的功能，最大限度满足现代化大生产的控制与管理的需要。 现代 PLC 控制技术将向体积更小、功能更强、价格更低、速度更快的微小型方向发展，同时也会朝着大型网络化、兼容性好、功能全及可靠性高的方向发展。在网络信息技术高速发展的时代，PLC 控制技术也将逐步得到优化，也必将拥有更为广阔的发展前景。 七.PLC在电气自动化中的发展趋势 伴随着科技的发展，全球工业计算机控制领域已经发生巨大变 革，PLC几乎到处都 有，对于PLC控制器的核心—控制软件来讲，开放式的编程组态工具软件以及开放式通信网络技术的突破，将PLC推向了更加开放的工业控制行业。 PLC控制系统在高端应用方面，将和工业PC控制系统相媲美，因为这两者在微处理器和内存芯片方面十分相似，将来的发展趋势是将更多的功能进一步集成到一个控制箱内，以方便用户的操作和使用，像顺序控制和过程控制将会采用功能化方式进行处理，其他类似运动控制等也能够共享到相同的控制结构体系中。可以相信，PLC技术的发展继续沿着开放式控制系统的方向，尤其是基于工业PC的控制系统。为了更好的提供用户使用，PLC在人机界面方面要做的完美、通信设备要更加完备、现场总线通信能力要更加的成熟，这样才能更好地适应各种不同工业控制场合的需求。除了在灵活性方面比传统PLC具有截然不同的优势外，还要做到能够缩短系统投放到市场的周期，并能降低系统投资费用，提高从工厂底层到企业办公自动化的数据信息流动效率等，这将是PLC未来发展不可抵挡的趋势。 结论:综上所述，PLC 技术在电气自动化控制中是一项先进的技术，它克服了传统电气自动化控制系统的诸多缺点，减少了材料消耗，减少了维护工作，帮助企业节省资源，提高企业的工作效率。同时 PLC 在电气自动化控制中的应用又需要进一步的发展，要突破现有的技术瓶颈，做到在各种环境下都能让PLC 运用到电气自动化的控制之中，同时，需要对现有的 PLC 技术进行改进，使之能在高温高压以及高电磁辐射等各种复杂的环境下进行工作，这样 PLC 在电气自动化控制中的应用才能得到充分的扩展和全面的开发利用。 参考文献 [1] 刘铁中.PLC技术在电气设备自动化控制中的应用.[J].科技视界，2013 [2] 于军，苗百春.PLC技术在电气自动化中的应用.[J].科技资讯，2013 [3] 张俊莉.PLC在电气自动化中的应用探究.[A].第二届“科协文化——中关村论坛”论文集. [4] 王华琳.PLC在电气自动化控制中的应用.[J].信息与电脑（理论版），2013 [5] 孙胜涛.PLC 在电气自动化控制中的应用分析.[J].电子技术与软件工程，2013， Introduction and application of PLC technology Abstract: With the continuous development of computer technology, PLC technology in the electric automatic control is becoming more and more widely applied in the field of manufacturing and research and development, play an irreplaceable role. PLC technology in the application of the electric equipment automation control based on Microsofts processor as the foundation, combined with the present computer technology, automatic control technology, modern communication technology and other advantages, greatly extend the application of PLC technology in the electric equipment automation control applicable areas, have very strong effectiveness. PLC technology has high flexibility, high reliability, convenience, and industrial robots, CAD/CAM and three big pillar of modern industrial automation. This paper introduces what is the PLC technology, PLC technology in electrical equipment of the advantage and application of automation control, hope to have certain reference function. Keywords: The PLC technology, Electrical equipment; Automatic control 1.The concept of PLC technology Is English PLC Programmable Controller Programmable logic Controller, which is based on microprocessor, combined with communication, computer, Internet and automatic control technology on the development of industrial control device. PLC technology originated in the 1970 s, has been successfully applied in automobile industry. As the technology of PLC, processing speed, control the progress of the various functions and commercialized, its applications in electrical equipment automation is also becoming more and more widely, formed the instrument - appliances - the integration of computer control mode. The PLC technology in the application of products and production, with DCS DCS and FCS bus control system as the main form. The development of PLC technology in the future, will not just as a basic system, but a whole distributed, open control system. 2.The structure of the PLC The essence of P L C technology is applied in the industrial control computer technology, as a result, the hardware structure is the basic consistent with most computer structure, all include: power supply, C P U , memory module, function module, letter, input/output interface circuit and so on. 3. The working principle of PLC The first step, the input samples. In this step, programmable controller read sampling data mainly through the way of scanning, and then use the input in the I/O output image area of the storage unit of the data. After the sampling data is input, continue to implement the output refresh operation to turn to the user program. The second step, the program execution. In the process of the user of the program execution, programmable controller for the user program to scan the execution order from top to bottom, always in the process of scanning, its operation shall be carried out in accordance with the fixed order and route, among them, the scanning sequence is from left to right, from top to bottom, and the scanning line is made up of each user program to get an electric shock. The third step, the system output refresh. The operation to be completed at this stage is a programmable controller to refresh after the execution of the user program. In the refresh process, the system CPU I/O output will be based on the input image in the corresponding state and the previous phase of the input data to latch circuit, then complete the drive for other peripherals. 4. PLC main characteristic analysis (1) Has high cost performance, fully functional. PLC controller contains a large number of programming components used by users, has the very strong and complete control function, still can use communication network to realize centralized management but decentralized control. (2) Strong anti-interference ability on the one hand, the application of PLC on a large scale integrated circuit technology, adopts advanced anti-jamming processing techniques in the production process, such as internal power to shield, voltage regulator, protection; Set up the independent power supply, input/output interface circuit from their own hardware to enhance its anti-jamming ability and reliability of equipment. On the other hand, through the correct selection of grounding location and improve the system, and the sealing, dustproof, seismic encapsulation shell, also can have good reduce interference effect. Through the above measures can make the PLC in a relatively harsh environment and reliable work, and to reduce the incidence of failure, improve the reliability of the system. (3) The PLC controller has the advantages of convenient installation, easy maintenance, simple operation, PLC controller failure, the failure cause by its operation and fault indication device, check out the users in the system failure occurs, immediately take measures to replace modules such as measures to restore, PLC user interface simple and clear at the same time, it is very easy for users to master. 5. Application of PLC in power system are reviewed (1) Sequential control. In the thermal power system, its internal auxiliary system of technological process can be divided into two ways, namely, switch control and sequence control. Along with our countrys emphasis on energy and environmental protection degree is more and more high, so in the thermal power industry, the production process of saving resources have become the target of each enterprise management. In order to reach the ultimate goal of energy conservation and emissions reduction, it is necessary to improve the automatic control level of the enterprise auxiliary workshop. With the advent of PLC control technology, in the auxiliary system of thermal power enterprises, the traditional relay controller is replaced by PLC control system, basic at the same time, with the constant progress of science and technology, PLC control system can not only to a single technological process for effective control, and be able to connect to PLC communication always To coordinate the way for the whole production line. (2) the switch quantity control Circuit breaker control. Original type thermal power system with electromagnetic relay as the main components of the controller, the system USES a large amount of electromagnetic components, so its a lot of contact greatly reduce the reliability of the system, simultaneously this system also has the disadvantages such as complex wiring, maintenance difficulties, and the application of PLC in recent years with a lot of soft relay instead of a lot of physical yuan, accordingly Greatly improve the reliability, operators need to closing operation, simple points in the process of operating system can be based on the actual operation and the corresponding indicator is given. Automatic switching. In order to enhance the reliability of power supply and standby power automatic device years ago used in thermal power enterprises, initially for the back line for manual or automatic operation, while the operating process often takes a few seconds, but for continuous electrical requirements of the user is not allowed, therefore, in order to improve the reliability of supply electricity, composed of PLC of standby power automatic device, it can be programmed to use all kinds of operation mode, it will be a equipment normal operation signals were collected as a basis for the standby power on or off, due to the control system with functions of data processing and logical judgment, so it can not only complete the reserve power source operation, and it can consider the system running situation and other operation requirements, at the same time, the system itself has a strong anti-interference ability, and has high reliability, simple wiring, debugging, convenient operation and low cost etc. (3) closed loop control Pump motor. Thermal power into the general pump startup mode automatically start, screen machine manual start and run several field manual control box. Automatic condition of pump is powered by PLC in sequence control module based on the accumulation of each pump running length of time to choose the main spare pump; And beside the machine screen open means is to adjust the switch to open/close pump, its main standby pump is based on human compare to run time to determine each pump type, while in the scene to manipulate it will switch to "manual" governor gear to achieve. 6. The application prospects of PLC in electrical automation Control and management integration. On a controller to control and information processing functions at the same time, PLC adopts computer information processing technology and network communication technology and graphics display technology, makes the production control function of PLC system and information management functions, to further improve the function of PLC, the maximum meet the needs of the modern production control and management. Modern PLC control technology to a smaller, more powerful and cheaper and faster microminiature direction, as well as toward a large network, good compatibility, full functions and high reliability. In the era of network information technology high speed development, PLC control technology will gradually optimized, will surely have a broader development prospects. 7. The development trend of PLC in electrical automation Along with the development of science and technology, tremendous changes have occurred in the field of global industrial computer control, PLC, almost everywhere, for the core of the PLC controller, control software, programming configuration tool software and open communication network technology breakthrough, PLC will be more open to the industrial control industry. PLC control system in high-end applications, and industrial PC control system, which is quite similar in terms of the microprocessor and memory chip, the development trend of the future will be more further integrated into the function of a control box, with convenient operation and use of the user, such as sequence control and process control will be using functional way to deal with, other similar motion control and so on also can share the same control structure system. Are to be believed, the development of PLC technology to continue along the direction of the open control system, especially the control system based on industrial PC. In order to better provide users, PLC in the aspect of man-machine interface to do perfect, communications equipment more complete, fieldbus communication ability will be more mature, so as to better adapt to the demand of various industrial control occasions. In addition to the flexibility than traditional PLC has a distinct advantage, but also can shorten the cycle of system into the market, and can reduce the investment cost of the system and improve the bottom from the factory to the data flow of information efficiency of enterprise office automation, etc., this will be the future developmen