集散控制系統(tǒng) 畢業(yè)論文 英文翻譯.doc

集散控制系統(tǒng)一個典型的DCS控制系統(tǒng)集散控制系統(tǒng)（Distributed control system）是以微處理器為基礎的對生產過程進行集中監(jiān)視、操作、管理和分散控制的集中分散控制系統(tǒng)，簡稱DCS系統(tǒng)。該系統(tǒng)將若干臺微機分散應用于過程控制，全部信息通過通信網絡由上位管理計算機監(jiān)控，實現最優(yōu)化控制，整個裝置繼承了常規(guī)儀表分散控制和計算機集中控制的優(yōu)點，克服了常規(guī)儀表功能單一，人-機聯系差以及單臺微型計算機控制系統(tǒng)危險性高度集中的缺點，既實現了在管理、操作和顯示三方面集中，又實現了在功能、負荷和危險性三方面的分散。DCS系統(tǒng)在現代化生產過程控制中起著重要的作用。集散控制系統(tǒng)一般有以下四部分組成： 現場控制級又稱數據采集裝置，主要是將過程非控變量進行數據采集和預處理，而且對實時數據進一步加工處理，供CRT操作站顯示和打印，從而實現開環(huán)監(jiān)視，并將采集到的數據傳輸到監(jiān)控計算機。輸出裝置在有上位機的情況下，能以開關量或者模擬量信號的方式，向終端元件輸出計算機控制命令。 這一個級別直接面對現場，跟現場過程相連。比如閥門、電機、各類傳感器、變送器、執(zhí)行機構等等。它們都是工業(yè)現場的基礎設備、同樣也是DCS的基礎。在DCS系統(tǒng)中，這一級別的功能就是服從上位機發(fā)來的命令，同時向上位機反饋執(zhí)行的情況。拿軍隊來舉例的話，可以形容為最底層的士兵。它們只要能準確地服從命令，并且準確地向上級匯報情況即完成使命。至于它與上位機交流，就是通過模擬信號或者現場總線的數字信號。由于模擬信號在傳遞的過程或多或少存在一些失真或者受到干擾，所以目前流行的是通過現場總線來進行DCS信號的傳遞。 過程控制級又稱現場控制單元或基本控制器，是DCS系統(tǒng)中的核心部分。生產工藝的調節(jié)都是靠它來實現。比如閥門的開閉調節(jié)、順序控制、連續(xù)控制等等。 上面說到現場控制級是“士兵”，那么給它發(fā)號施令的就是過程控制級了。它接受現場控制級傳來的信號，按照工藝要求進行控制規(guī)律運算，然后將結果作為控制信號發(fā)給現場控制級的設備。所以，過程控制級要具備聰明的大腦，能將“士兵”反饋的軍情進行分析，然后做出命令，以使“士兵”能打贏“戰(zhàn)爭”。 這個級別不是最高的，相當于軍隊里的“中尉”。它也一樣必須將現場的情況反饋給更高級別的“上校”也就是下面講的過程管理級。 過程管理級DCS的人機接口裝置，普遍配有高分辨率、大屏幕的色彩CRT、操作者鍵盤、打印機、大容量存儲器等。操作員通過操作站選擇各種操作和監(jiān)視生產情況、這個級別是操作人員跟DCS交換信息的平臺。是DCS的核心顯示、操作跟管理裝置。操作人員通過操作站來監(jiān)視和控制生產過程，可以通過屏幕了解到生產運行情況，了解每個過程變量的數字跟狀態(tài)。這一級別在軍隊中算是很高的“上校”了。它所掌握的“大權”可以根據需要隨時進行手動自動切換、修改設定值，調整控制信號、操縱現場設備，以實現對生產過程的控制。 經營管理級又稱上位機，功能強、速度快、容量大。通過專門的通信接口與高速數據通路相連，綜合監(jiān)視系統(tǒng)各單元，管理全系統(tǒng)的所有信息。 這是全廠自動化系統(tǒng)的最高一層。只有大規(guī)模的集散控制系統(tǒng)才具備這一級。相當于軍隊中的“元帥”，他們所面向的使用者是廠長、經理、總工程師等行政管理或運行管理人員。 它的權限很大，可以監(jiān)視各部門的運行情況，利用歷史數據和實時數據預測可能發(fā)生的各種情況，從企業(yè)全局利益出發(fā)，幫助企業(yè)管理人員進行決策，幫助企業(yè)實現其計劃目標。 DCS系統(tǒng)的產生背景上世紀30年代40年代，工業(yè)自動化裝置采用的是分散性控制系統(tǒng)。也就是所有設備都是獨立運行，不聯網控制。操作員根據生產需求進行計算后，將獨立設備的特性調節(jié)到適合的程度，然后就開始工作。之后采用了氣動、電動模擬儀表組成過程控制系統(tǒng)，實現了一定程度上的集中監(jiān)視、操作和分散控制。較好的適應了工業(yè)生產的需求。可是，隨著生產規(guī)模和復雜程度的不斷提高，原有的控制系統(tǒng)顯得滯后、笨重、繁冗、因為一臺儀表只有一種控制規(guī)律，要實現某些復雜的控制就很困難。另外，控制儀表數量越來越多，用原來落后的儀表盤控制的話，控制盤越來越長，看得人眼睛都會花掉。最致命的就是老系統(tǒng)之間不便于實現通信，很難分級控制和綜合管理。再一個就是它的系統(tǒng)變更比較麻煩，只有通過更換儀表和變更儀表連線才能實現。 第三次科技革命開始后，隨著計算機技術的發(fā)展，人們開始嘗試將計算機用于過程控制。試圖利用計算機所具有的功能特點，來克服常規(guī)模擬儀表的局限性。但當時采用的辦法是用一臺計算機控制幾十甚至上百個回路，這樣做的危險性很高，如果計算機出現故障，會導致很嚴重的后果，這就是所謂的“危險集中”。若采用雙機雙工系統(tǒng)，雖可以提高系統(tǒng)的可靠性，但成本太高，如果工廠的生產規(guī)模不大，則經濟性很差，用戶難以接受。 直到上世紀70年代開始，隨著計算機技術的日漸成熟，大規(guī)模集成電路及微處理器的誕生后，人們開始思考是否能將“危險分散”。就是原來靠一臺大計算機完成的“艱巨”任務，能否用幾十臺微處理來完成？這樣的話，即使某一處理器壞了，也不至于會“牽一發(fā)而動全身”，從而使危險系數大大降低。答案是肯定的。至此DCS就誕生了。 進入九十年代以后，計算機技術突飛猛進，更多新的技術被應用到了DCS之中。PLC是一種針對順序邏輯控制發(fā)展起來的電子設備，它主要用于代替不靈活而且笨重的繼電器邏輯?，F場總線技術在進入九十年代中期以后發(fā)展十分迅猛，以至于有些人已做出預測：基于現場總線的FCS將取代DCS成為控制系統(tǒng)的主角。 集散控制系統(tǒng)的特點DCS控制系統(tǒng)與常規(guī)模擬儀表及集中型計算機控制系統(tǒng)相比，具有很顯著的特點。 1、系統(tǒng)構成靈活。從總體上看，DCS就是由各個工作站通過網絡通信系統(tǒng)組網而成的。你可以把他現象成“因特網”。根據生產需求，你可以隨時加入或者撤去工作站。系統(tǒng)組態(tài)很靈活。 2、操作管理便捷。DCS的人機反饋都是通過CRT跟鍵盤、鼠標等實現的。你可以想象成在因特網沖浪一樣，你可以監(jiān)視生產裝置乃至整個工廠的運行情況。 3、控制功能豐富。原先用模擬控制回路實現的復雜運算，通過高精度的微處理器來實現。難道還有什么算法CPU實現不了的嗎？！ 4、信息資源共享。你可以把工作站想象成因特網上的各個網站，只要你在DCS系統(tǒng)中，并且限夠大，你就能了解到你要的任何參數。 5、安裝、調試方便。相比原先的模擬控制系統(tǒng)，那么多的飛線頭，一大堆類似頭發(fā)絲的電線。DCS系統(tǒng)算是很方便了。 DCS系統(tǒng)的硬件結構DCS的硬件系統(tǒng)主要由集中操作管理裝置、分散過程控制裝置和通信接口設備等組成。通過通信網絡將這些硬件設備連接起來，共同實現數據采集、分散控制和集中監(jiān)視、操作及管理等功能。 現場控制站現場控制站中的主要設備是現場控制單元?，F場控制單元式DCS直接與生產過程進行信息交互的IO處理系統(tǒng)，它的主要任務是進行數據采集及處理，對被控對象實施閉環(huán)反饋控制、順序控制和批量控制。用戶可以根據不同的應用需求，選擇配置不同的現場控制單元構成現場控制站。它可以是以面向連續(xù)生產的過程控制為主，輔以順序邏輯控制，構成的一個可以實現多種復雜控制方案的現場控制站；也可以是以順序控制、連鎖控制功能為主的現場控制站；還可以是一個對大批量過程信號進行總體信息采集的現場控制站。 現場控制站是一個可以獨立運行的計算機檢測控制系統(tǒng)。由于它是專為過程檢測、控制而設計的通用型設備，所以其機柜、電源、輸入輸出通道和控制計算機等，與一般的計算機系統(tǒng)有所不同。 A typical DCS control system DCS (Distributed control system) is a microprocessor-based centralized onitoring of the production process, operation, management, centralized and decentralized control of distributed control system, called DCS. The system will be used in a number of units distributed process control computer, all information through the communication network by the host management computer monitor, to achieve optimal control, the device inherits the conventional instrument distributed control and the advantages of computer control to overcome the normal function of a single instrument, Human - Machine Contact poor and the single risk of micro-computer control system of a high concentration of defects, both achieved in the management, operation and display of three concentrate, but also realized in functionality, load and risk of spread in three areas. DCS system in the modern production process control plays an important role. Distributed control systems typically have the following four components: Field control level known as data acquisition devices, mainly the non-control variables during data acquisition and preprocessing, and further processing of real-time data for the CRT display and print operation station, in order to achieve open-loop monitoring, and collected data to monitoring computer. Output device in a PC case, or can switch analog signals the way the computer output to the terminal device control commands. This is one level directly to the scene, the process is connected with the site. Such as valves, motors, sensors, transmitters, actuators and so on. They are the basis for industrial field device, it is also the basis of DCS. In the DCS system, this level of function is to obey the commands sent by the host computer, while upward-bit machine feedback implemented. Take for example the armed forces to the case, can be described as the bottom of the soldiers. They just follow orders accurately and precisely report the situation to higher authorities to complete the mission. As for its exchange with the host computer is through the analog signal or fieldbus digital signal. Because analog signals in the transmission process, there are some more or less distortion or interference, so by popular fieldbus for DCS signals. Process control levelAlso known as the basic field control unit or controller, is the core part of the DCS system. Relied on the regulation of production processes are achieved. Such as regulating the opening and closing valves, sequence control, continuous control and so on.Speaking of field control level is above the soldiers, then it is in command of the process control level. It accepts signals coming from field control level, control law in accordance with the requirements of computing technology, and the results sent to the scene as a control signal level control device. Therefore, the process control level to have a smart brain, able to soldiers to analyze the feedback of the military, and then make an order to make the soldiers can win war. his level is not the highest, equivalent to the armys lieutenant. It must be the same site feedback to a higher level of Colonel is the following about the process management level.Process management levelDCS man-machine interface device, generally with a high resolution, large screen color CRT, the operator keyboard, printer, mass storage and so on. Select the operator station through the operation of various operating and monitoring production, This level is the operator with the DCS platform for exchange of information. DCSs core is shown operating with the management device. Operator through the operator station to monitor and control the production process, production can be learned through the operation of the screen to see the number of process variables with each state. This level be high in the armed forces, Colonel was. Its possession of power as needed to manually switch automatically at any time, modify the settings, adjust the control signals, control field devices to achieve the control of the production process.Management levelAlso known as the host computer, features, speed, large capacity. Through dedicated communication interface and high-speed data path connected, integrated surveillance system unit, and managing all system information.This is the highest whole plant floor automation systems. Only large-scale distributed control system is qualified for this level. The military equivalent of the Marshal, they are for the user is a director, manager, chief engineer and other administrative or operational management personnel.Its a great privilege, you can monitor the operation of various departments, the use of historical data and real-time data to predict the various situations that may occur from the overall interests of business to help business executives make decisions to help companies achieve their program objectives.DCS system background40s 30s last century, industrial automation equipment is used in dispersion control system. All equipment is run independently, not networked control. Operator calculated based on production requirements, will be independent of device characteristics to the appropriate level of regulation, and then began to work. After using a pneumatic, electric analog instrument into the process control system, a certain degree of centralized monitoring, operation and decentralized control. Better adapted to the needs of industrial production. However, with the production scale and complexity of the continuous improvement of the existing control system appears to lag, heavy, cumbersome, because a meter is only one control law to achieve some of the complex control is difficult. In addition, an increasing number of control instruments, using the original control of the instrument panel behind the words, the control panel and longer, to see peoples eyes will be spent. The most deadly is the old systems are not easy to implement communication, control and integrated management of difficult classification. Another is that it is too much trouble to change the system only changes through the replacement of meters and meter connections can be achieved.After the beginning of the third technological revolution, with the development of computer technology, people began to try to computers for process control. Have tried to use the computer features, to overcome the limitations of conventional analog gauges. But then the approach is to use a computer control dozens or even hundreds of loops, a high risk of doing so, if the computer fails, will lead to very serious consequences, and this is the so-called dangerous concentration. The use of a dual-duplex system, although you can improve system reliability, but the cost is too high, if the factorys production is small, then the economy is poor, the user is difficult to accept.Until the last century, 70 years, with increasingly sophisticated computer technology, the birth of large scale integrated circuits and microprocessors, people can start thinking about whether the dangerous spread. NTU is the original by a computer to complete the arduous task, can use dozens of micro-processing to complete? In this case, even if a processor is broken, that does not will affect the situation as a whole, so that greatly reduced the risk coefficient. The answer is yes. Thus was born the DCS.Into the next decade, computer technology advances, more new technology is being applied to the DCS. PLC is a sequential logic control developed for electronic equipment, which is used instead of inflexible and cumbersome relay logic. Fieldbus Technology in entering developed very rapidly since the mid nineties that some people have to predict: FCS based on field bus control system will replace the DCS as the protagonist.The characteristics of distributed control systemDCS control system with conventional analog gauges and centralized computer control system, compared with a very significant features.1, the system constitutes a flexible. Overall, DCS is the workstations through the network by the network communications system formed. You can put him into the phenomenon of Internet. Based on production needs, you can join at any time or removed workstations. System configuration is very flexible.2, operation and management easy. DCS through human-machine feedback CRT with keyboard, mouse, etc. to achieve. You can imagine the same as surfing the Internet, you can monitor the production device and the whole plant operation.3, the control feature-rich. The original analog control loop with the complex operations realized by the microprocessor to achieve high accuracy. Is there any method to achieve CPU can not it? !4, information resource sharing. You can imagine the station each site on the Internet, as long as you are in the DCS system, and permission is large enough, you can understand that any parameters you want.5, installation and debugging. Compared to the original analog control system, so many flying thread, a lot of hair like wires. DCS system be very convenient.DCS system hardware structureDCS hardware system mainly from centralized operations management device, distributed process control devices and communications interface devices and other components. Thr