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機(jī)械與電氣工程學(xué)院 畢業(yè)設(shè)計(jì) 論文 外文翻譯 所在學(xué)院 機(jī)電學(xué)院 班 級 08 機(jī)自 6 班 姓 名 沈玉萍 學(xué) 號(hào) 08141010626 指導(dǎo)教師 龔方 合作導(dǎo)師 2011 年 12 月 9 日 原文 DCS Based Process Control Simulating System Abstract A distributed control system DCS based on two layer networks for experimental teaching is presented in this paper Three sets of equipments are used as process objects with their parameters such as pressure temperature level and flow rate being controlled variables This system has multiform training functions Students can not only set up basic experiments about the process control but can also design complicated control system The result of 4 years use shows it is an ideal engineering simulating system for students major in industrial automation Key Words DCS process control simulating system experimental teaching network 1 INTRODUCTION Control education is an integral part of the community s activities and one of its most important mechanisms for transition and impact In 1998 the National Science Foundation NSF and the IEEE Control Systems Society CSS jointly sponsored a workshop in control engineering education which made a number of recommendations for improving control education One of them is about experiments Experiments continue to form an important part of a control education and projects should form an integral part of the curriculum for both undergraduate and graduate students The idea of using distributed control system for process control emerged in the 1970s Now it is widely used in manufacturing chemicalindustry papermaking textile food processing power etc DCS integrating advanced computer control communications and CRT technologies has played an important role in raising technological level reducing cost and making production more flexible and integrated So it is very important to establish a DCS simulating system in university We have set up the system in 2002 The system can bring more understanding of real world problems to the students 2 SYSTEM BUILDUP Most modern industrial process control system adopts two layer network topological structure The lower one field bus comes close to the process and the upper one Ethernet mainly locates inside control room Such structure disperses control and centralizes management and operation Our system bases just this structure with the benefits of letting students familiar with current industrial network control As shown in Figure 1 our system consists of 16 operator stations one I O station and 3 sets of process equipments 2 1 The Distributed Computer System From Figure 1 we can see that the distributed computer system is connected by two layer networks The monitoring network is implemented via 10M 100M pen Ethernet The TCP IP protocol is used The buses connected by I O stations and operator stations are information channels for plantwide supervision and control According to the specifications of a process the web server linked to Internet can also be set to achieve remote monitor This network is arranged redundantly so the system proves reliable The field network interconnected by I O station and its I O modules uses Profibus DP and transmits a variety of information and parameters in real time The operator stations are general purpose PCs They act as engineering stations when used for off line configuration so 16 students can program at the same time While for on line use the students can monitor and control the process on these PCs The I O station is a domestic product developed by Beijing Hollysys Co Ltd Its design adopts standardization and modularization The I O station based on high performance microprocessors and mature control algorithms can response as soon as possible to the internal and external events It has 5 local modules i e two FM148 analog input cards one FM151 analog output ard one FM161 digital input card and one FM171 digital output card Each card has particular microprocessor responsible for its control test calculation and diagnosis thus enhancing its selfcontrol level and dramatically improve its reliability and safety The station or modules can be shifted without disturbance in case of trouble Therefore the system is able to control in real time and with high quality 2 2Process Equipments Process control is an important course of automatic major After learning the theories in the classroom the students have an eager for digesting and understanding The control community has a strong history of impact on many important problems and industry involvement will be critical for the eventual success of the future directions How to imitate industrial process is an important concern We have built 3 sets of equipments representing pressure process level process temperature and flow rate process individually The three sets of equipments can also be used for normal instrumentation control or direct digital control All the connections are wired to the panel so does the I O station The process equipments can be flexibly linked to different controller by plug contacts on the panels There are different kinds of transducers installed on the process to provide a variety of signals such as tempera ture level pressure and flow rate These signals are analog inputs to DCS The final operating elements include electric heater switching components and control valves DCS outputs analog or digital signals to the elements The combination of the process equipments with the distributed computer system explores the frontiers of control including increased use of computing communications and networking as well as exploration of control in application domains 3 SOFTWARE CONFIGURATION AND OPERATION In the computer control field it has been customary to overcome some of the programming problems by providing table driven software A user of the DCS is provided with a configuration package that allows the user to generate a DCS system simply by configuring so very little effort is needed to program The package providing device database control scheme graph and report forms configuration is run off line on the engineering station Configuration of the DCS is implemented from up to down by conforming to hardware structure It is divided into the following 5 steps Devices registration to configure system hardware including the number of I O stations or operator stations along with their network addresses and each I O station s hardware such as data transmission card I O card Database configuration to define signal points and parameters set Control scheme configuration classified as conventional configuration which provides many control blocks like feedback cascade ratio and self defined one that is programmed in real time control language similar to BASIC Graph configuration to make various pictures such as survey standard display adjust control trend flow chart alarm displayed on high resolution color CRT and compound windows more abundant and menu function more live this configuration to configure diagrams for operator to monitor and control the process in real time Report forms configuration to provide statistic report of the process Before running the software all the configurations must be compiled linked and downloaded to the operators where several networked PC sharing the overall workload are able to monitor and control all aspects of process from a variety of live displays and friend interactions Or the operator will run the system downloaded last time The operator is extended with flat sealed film keyboard touch screen and global mouse to let operations easier Through the man machine interaction the process data can be collected analyzed recorded and controlled in real time the system structure and configure loops can be modified on line local breakdown can be fixed on line Once the process is abnormal the hardware will self diagnose and inform the operator stations that personnel around the field find the breakdown and that the indicator lamps on cards on I O station shows the fault location Such dual means of indication together with breakdown alarm and hot plug in plug out make it possible to fix breakdown on line and to run system safely and reliably 4 EXPERIMENTAL PROJECTS Our DCS simulating system can train 16 students at the same time The training functions are versatile from hardware and software configuration to complicated system design and debug By I O station 11 inputs from the 3 sets of equipments are measured and controlled 7 control valves and 1 electric heater of the processes are manipulated in real time to implement temperature pressure level and flow rate control breakdowns are detected and the system is maintained Live measured values and status indications reveal the current situation Process operators monitor and control the long distance processes from their own consoles The students operate the system as if they are in the real world industrial automation The flow chart of temperature and flow rate control sys tem is shown in Figure 2 T1 T2 are measured temperature of the inner and outer water tank FT1 FT2 are flow rate of the water into the inner and outer tank WVL1 and WVL2 are two outputs from the I O station to change the open range of the valves ZK is a switch for turning on or off the electric heater This system control is made up of 2 single variable closed loops T1 control and FTI Control 1cascade T1 T2 and 1proportion FT1 FT2 loop All loops adopt normal PID which parameters can be dynamic adjusted from the operator station The four control loops and main chart of the system can be easily shifted by pressing the buttons on the bottom of the graph as shown in Fig 2 5 CONCLUSION The result of 4 years use for both undergraduate and graduate shows experimental training is especially efficient to help students understand the technique of industry process the dynamic characters of the control system and to improve students ability to operate and control the process The convenient hardware connections make the DCS teaching system easily operated and the effortless software configuration renders different control algorithms implemented flexibly Besides basic experiments about the process control students have also designed complex control system to meet stricter product specifications 譯文 基于 DCS 過程控制仿真系統(tǒng) 摘要 本文提出的是一個(gè)建立在實(shí)驗(yàn)教學(xué)雙層網(wǎng)絡(luò)上的分布式控制系統(tǒng) DCS 其中配備三套設(shè)備 用于監(jiān)測實(shí)驗(yàn)過程對象中自身的流量 水平 溫度的次數(shù) 變量 該系統(tǒng)具有多種形式的培訓(xùn)職能 學(xué)生不僅可以設(shè)立有關(guān)控制程序的基 本實(shí)驗(yàn) 而且還可以設(shè)計(jì)復(fù)雜的控制系統(tǒng) 經(jīng)過 4 年的使用結(jié)果表明 DCS 過 程控制仿真系統(tǒng)是一個(gè)非常理想的工程模擬系統(tǒng) 我們可以利用它做工業(yè)自動(dòng) 化的學(xué)習(xí)研究 關(guān)鍵詞 DCS 過程控制 仿真系統(tǒng) 實(shí)驗(yàn)教學(xué) 網(wǎng)絡(luò) 1 緒論 控制系統(tǒng)的教育機(jī)構(gòu)是社會(huì)體系中的組成部分 在有舉足輕重的位置 它 是一個(gè)重要的轉(zhuǎn)變和影響機(jī)制 在 1998 年 美國國家科學(xué)基金會(huì) NSF 和電 氣和電子工程師控制系統(tǒng)協(xié)會(huì) CSS 聯(lián)合舉辦教育控制工程教育研討會(huì) 本提 出了如何改善控制系統(tǒng)的教育機(jī)構(gòu)的若干建議 其中就有關(guān)于實(shí)驗(yàn)的提議 研 究人員表明 DCS 過程控制系統(tǒng)應(yīng)當(dāng)始終作為控制系統(tǒng)學(xué)習(xí)的重要組成部分 應(yīng) 作為對本科生和研究生課程的組成部分 上世紀(jì) 70 年代 分布式控制系統(tǒng)就出 現(xiàn)在過程控制應(yīng)用之中 到現(xiàn)在 它被廣泛用于制造 化工 造紙 紡織 食 品加工 電力等各種領(lǐng)域 分布式控制系統(tǒng)結(jié)合了先進(jìn)的計(jì)算機(jī) 控制 通信 和 CRT 技術(shù) 為生產(chǎn)技術(shù)水平不斷提高 減少成本起到重要的作用 使得生產(chǎn) 更具有靈活性和綜合性 如此看來 我們在大學(xué)期間 建立一個(gè) DCS 仿真系統(tǒng) 是非常重要的 在 2002 年 我們成功建立了這個(gè)系統(tǒng) 該系統(tǒng)的建立 可以讓 學(xué)生更多的了解實(shí)際遇到的問題 2 系統(tǒng)建立 大多數(shù)現(xiàn)代工業(yè)過程控制系統(tǒng)都是采用兩層網(wǎng)絡(luò)拓?fù)浣Y(jié)構(gòu) 系統(tǒng)采用一個(gè) 較低的現(xiàn)場總線來關(guān)閉進(jìn)程 用一個(gè)以太網(wǎng)來控制整個(gè)系統(tǒng)操作 使用這種分 散式結(jié)構(gòu)控制和集中管理和運(yùn)作 我們的系統(tǒng)就是基于這樣的機(jī)構(gòu)上 可以更 有利于學(xué)生熟悉目前的工業(yè)控制 如圖 1 我們的系統(tǒng)包括 16 個(gè)操作站 一個(gè) I O 站和 3 套加工設(shè)備 2 1 分布式計(jì)算機(jī)系統(tǒng) 我們從圖 1 的分布式計(jì)算機(jī)系統(tǒng)可以看出 分布式計(jì)算機(jī)系統(tǒng)是由 2 層網(wǎng) 絡(luò)連接組成 該監(jiān)測網(wǎng)絡(luò)是通過 10M 100M 以太網(wǎng)實(shí)施控制 并在 TCP IP 協(xié) 議下使用 系統(tǒng)由總線連接各個(gè) I O 站點(diǎn) 操作員站連接所有信息渠道 可以 在整個(gè)系統(tǒng)范圍進(jìn)行監(jiān)督和控制 依據(jù)整個(gè)過程的結(jié)構(gòu) 在網(wǎng)絡(luò)服務(wù)器鏈接到 互聯(lián)網(wǎng)的 條件下 也可以設(shè)置實(shí)現(xiàn)遠(yuǎn)程控制 該網(wǎng)絡(luò)采用冗余安排 以便使得系統(tǒng) 絕對的可靠 外部網(wǎng)絡(luò)通過 I O 總站連接到系統(tǒng) 并在 I O 模塊中使用現(xiàn)場總 線段落準(zhǔn)確的傳輸各種信息和參數(shù) 操作站作為工程總站 通過主機(jī)的控制 在不在現(xiàn)場的情況下 可以讓 16 名學(xué)生同時(shí)進(jìn)行工程訓(xùn)練 而且學(xué)生可以使用電腦程序通過網(wǎng)絡(luò)對這些操作進(jìn) 程監(jiān)視和控制 該系統(tǒng) I O 控制站是基于北京和利時(shí)發(fā)展有限公司的產(chǎn)品 它 的設(shè)計(jì)采用標(biāo)準(zhǔn)化和模塊化 該 I O 站的基于高性能微處理器和成熟的控制 算法 能盡快回應(yīng)系統(tǒng)內(nèi)部和外部的各種操作 它由 5 個(gè)本地模塊組成 即兩 個(gè) FM148 模擬輸入卡 一 FM151 模擬輸出卡 一卡 FM161 數(shù)字輸入和一個(gè) FM171 數(shù)字輸出卡 每個(gè)卡都具有其特定的微處理器 負(fù)責(zé)不同的控制 測試 計(jì)算和診斷 由此來加強(qiáng)系統(tǒng)自身的控制水平 大大提高了它的可靠性和安全 性 在糟糕的情況下 這樣的控制站可以一直啟動(dòng)無干擾模式 由此可見 這 樣的系統(tǒng)可以保證高品質(zhì)的且非常準(zhǔn)確的控制 2 2 工藝設(shè)備 過程控制是一個(gè)非常重要并且艱巨的工程 學(xué)生通過課堂理論學(xué)習(xí)之后 需要進(jìn)一步去消化和理解 而這個(gè)控制系統(tǒng)在過去很多年里影響到很多重要事 件 而在未來的發(fā)展方向主要與各個(gè)行業(yè)的合作 這將是最終取得成功的關(guān)鍵 如何去模仿工業(yè)過程是一個(gè)重要的問題 我們已建立 3 個(gè)獨(dú)立設(shè)備 分別用于 代表壓力加工設(shè)備 工藝水平 溫度和流量水平 并且這 3 套的設(shè)備也可用于 正常儀表控制或直接數(shù)字控制 所有設(shè)備都通過線路連接到控制面板 同時(shí)也 連接到 I O 站點(diǎn) 并且可以自由的與控制面板上的任何插頭連接 在過程控制 系統(tǒng)中安裝有各種不同的傳感器 用于監(jiān)測如溫度 真實(shí)姿態(tài) 液位 壓力和 流量 給控制站反饋多種信息 這些信息通過模擬輸入到 DCS 然后通過電熱 水器 開關(guān)元件 和控制閥等操作元件控制整個(gè)過程 形成一個(gè)反饋系統(tǒng) 然 后集散控制系統(tǒng)輸出模擬或數(shù)字信號(hào)的元素 這套控制系統(tǒng)設(shè)備是與分布式計(jì) 算機(jī)控制系統(tǒng)結(jié)合而進(jìn)行的前沿探索 包括增加使用的計(jì)算 通信和網(wǎng)絡(luò) 以 及在應(yīng)用程序的控制等等 3 軟件配置和運(yùn)行 在計(jì)算機(jī)控制領(lǐng)域 已經(jīng)克服了驅(qū)動(dòng)軟件編程的一些問題 DCS 系統(tǒng)為用 戶提供一個(gè)配置包 允許生成一個(gè)簡單的 DCS 系統(tǒng)配置 所以用戶可以很輕松 的設(shè)計(jì)方案 這個(gè)提供有設(shè)備 數(shù)據(jù)庫 控制計(jì)劃 圖形和報(bào)表配置的系統(tǒng)包 在工程站內(nèi)可以離線運(yùn)行 DCS 的配置是順應(yīng)硬件結(jié)構(gòu)從上網(wǎng)下實(shí)現(xiàn)的 它分 為一下 5 個(gè)步驟 設(shè)備登記系統(tǒng)硬件配置 其中包括跟蹤其網(wǎng)絡(luò)的 I O 站或操作站地址和 每個(gè) I O 站的硬件 如數(shù)據(jù)傳輸卡 I O 卡 數(shù)據(jù)庫配置來定義信號(hào)點(diǎn)和參數(shù)設(shè)置 控制計(jì)劃配置列為常規(guī)配置 提供許多反饋控制塊 梯級 比率和自定義 這是類十余 BASIC 語言的實(shí)施控制程序 用圖像來顯示各種諸如調(diào)查 標(biāo)準(zhǔn)顯示 調(diào)整 控制 趨勢 流程圖的數(shù) 據(jù) 然后用高分辨率彩色顯像管和更豐富的復(fù)合窗口和菜單功能顯示操作現(xiàn)場 用此配置來配置運(yùn)行圖 一檢查和控制實(shí)時(shí)處理 報(bào)告提供的統(tǒng)計(jì)表格配置的進(jìn)程 在運(yùn)行該軟件下 所有的配置都將被編 譯 鏈接并下載到運(yùn)營商 這個(gè)運(yùn)行商必須有幾個(gè)聯(lián)網(wǎng)的電腦用于共享整體工 作情況 以便可以監(jiān)視和控制現(xiàn)場展示各種進(jìn)程的所有方面 或者經(jīng)營者將運(yùn) 行系統(tǒng)下載最后一次 經(jīng)營者擴(kuò)展了平面密封薄膜鍵盤 觸摸屏和鼠標(biāo) 讓所 有行動(dòng)更容易 通過人機(jī)互動(dòng)的過程中可以收集數(shù)據(jù) 分析 記錄和實(shí)時(shí)控制 該系統(tǒng)結(jié)構(gòu)和配置的循環(huán)可以被修改 在線 本地故障可在線修復(fù) 一旦這個(gè) 過程是不正常的 硬件會(huì)自動(dòng)診斷并通知操作員站 現(xiàn)場工作人員圍繞故障進(jìn) 行查找 并在卡片上我指示燈 O 站顯示故障位置 這種雙重手段的跡象說明 具有連接故障報(bào)警和熱插件插件可以實(shí)現(xiàn)在線修正線路故障 使得系統(tǒng)運(yùn)行的 更加安全可靠 4 實(shí)驗(yàn)項(xiàng)目 我們的 DCS 仿真培訓(xùn)系統(tǒng)可以讓 16 名學(xué)生同時(shí)操作 培訓(xùn)職能對硬件和軟 件配置復(fù)雜的系統(tǒng)設(shè)計(jì)和調(diào)試都是通用的 I O 站的 11 個(gè)輸入點(diǎn)由 3 臺(tái)進(jìn)行 測量和控制的設(shè)備 7 個(gè)控制閥和一個(gè)電加熱器的進(jìn)程實(shí)現(xiàn)的 用于實(shí)時(shí)操作 執(zhí)行溫度 壓力 液位 流量的控制和故障檢測和系統(tǒng)的維護(hù) 現(xiàn)場測量值和 狀態(tài)的跡象表明目前系統(tǒng)的運(yùn)行狀況 自身的操作站可以處理系統(tǒng)運(yùn)行的過程 監(jiān)控和控制 學(xué)生操作該系統(tǒng) 猶如他們是在現(xiàn)實(shí)工業(yè)自動(dòng)化操作中 溫度和 流量控制系統(tǒng) 透射電鏡流程圖如圖 2 所示 T1 和 T2 用來測量的內(nèi) 外水箱 的溫度 FT1 和 FT2 用來顯示內(nèi)外水箱的水流流速 WVL1 and WVL2 是兩個(gè)從 I O 站輸出的數(shù)值 控制閥門開啟程度 ZK 是一個(gè)打開或關(guān)閉電加熱器的開關(guān) 該系統(tǒng)的控制是由 2 個(gè)單變量閉合回路 T1 控制和 FTI 控制 一個(gè)串聯(lián) T1 T2 一個(gè)比例循環(huán) FT1 FT2 構(gòu)成 所有的回路采用從操作站動(dòng)態(tài)調(diào)整的常規(guī) PID 四個(gè)控制回路和系統(tǒng)的主要圖表可以很容易地轉(zhuǎn)向按本圖底部的按鈕 如 圖 2 所示 5 結(jié)論 在 4 年的本科和研究生的使用結(jié)果表明 實(shí)驗(yàn)培訓(xùn)可以非常有效的讓學(xué)生 了解產(chǎn)業(yè)的工藝技術(shù) 而這個(gè)控制系統(tǒng)的動(dòng)態(tài)特性 更可以提高學(xué)生的操作和 控過程的能力 便捷的連接 使 DCS 的硬件教學(xué)系統(tǒng)操作非常簡便 同時(shí)簡便 的軟件配置使得實(shí)施不同的控制算法變的非常靈活 除了對于過程控制的基本 實(shí)驗(yàn) 學(xué)生們還設(shè)計(jì)了復(fù)雜的控制系統(tǒng) 以滿足更嚴(yán)格的產(chǎn)品規(guī)格