DCS分布式控制系统中英文资料对照外文翻译文献综述

DCS分布式控制系统中英文资料对照外文翻译文献综述
DCS分布式控制系统中英文资料对照外文翻译文献综述

DCS分布式控制系统

中英文资料对照外文翻译文献综述

中文:

DCS

DCS是分布式控制系统的英文缩写(Distributed Control System),在国内自控行业又称之为集散控制系统。

即所谓的分布式控制系统,或在有些资料中称之为集散系统,是相对于集中式控制系统而言的一种新型计算机控制系统,它是在集中式控制系统的基础上发展、演变而来的。它是一个由过程控制级和过程监控级组成的以通信网络为纽带的多级计算机系统,综合了计算机,通信、显示和控制等4C技术,其基本思想是分散控制、集中操作、分级管理、配置灵活以及组态方便。在系统功能方面,DCS和集中式控制系统的区别不大,但在系统功能的实现方法上却完全不同。

首先,DCS的骨架—系统网络,它是DCS的基础和核心。由于网络对于DCS 整个系统的实时性、可靠性和扩充性,起着决定性的作用,因此各厂家都在这方面进行了精心的设计。对于DCS的系统网络来说,它必须满足实时性的要求,即在确定的时间限度内完成信息的传送。这里所说的“确定”的时间限度,是指在无论何种情况下,信息传送都能在这个时间限度内完成,而这个时间限度则是根据被控制过程的实时性要求确定的。因此,衡量系统网络性能的指标并不是网络的速率,即通常所说的每秒比特数(bps),而是系统网络的实时性,即能在多长的时间内确保所需信息的传输完成。系统网络还必须非常可靠,无论在任何情况下,网络通信都不能中断,因此多数厂家的DCS均采用双总线、环形或双重星形的网络拓扑结构。为了满足系统扩充性的要求,系统网络上可接入的最大节点数量应比实际使用的节点数量大若干倍。这样,一方面可以随时增加新的节点,另一方面也可以使系统网络运行于较轻的通信负荷状态,以确保系统的实时性和可靠性。在系统实际运行过程中,各个节点的上网和下网是随时可能发生的,特别是操作员站,这样,网络重构会经常进行,而这种操作绝对不能影响系统的正常运行,因此,系统网络应该具有很强在线网络重构功能。

其次,这是一种完全对现场I/O处理并实现直接数字控制(DDC)功能的网络节点。一般一套DCS中要设置现场I/O控制站,用以分担整个系统的I/O和控

制功能。这样既可以避免由于一个站点失效造成整个系统的失效,提高系统可靠性,也可以使各站点分担数据采集和控制功能,有利于提高整个系统的性能。DCS 的操作员站是处理一切与运行操作有关的人机界面(HMI-Human Machine Interface或operator interface)功能的网络节点。

工程师站是对DCS进行离线的配置、组态工作和在线的系统监督、控制、维护的网络节点,其主要功能是提供对DCS进行组态,配置工作的工具软件(即组态软件),并在DCS在线运行时实时地监视DCS网络上各个节点的运行情况,使系统工程师可以通过工程师站及时调整系统配置及一些系统参数的设定,使DCS 随时处在最佳的工作状态之下。与集中式控制系统不同,所有的DCS都要求有系统组态功能,可以说,没有系统组态功能的系统就不能称其为DCS。

DCS自1975年问世以来,已经经历了二十多年的发展历程。在这二十多年中,DCS虽然在系统的体系结构上没有发生重大改变,但是经过不断的发展和完善,其功能和性能都得到了巨大的提高。总的来说,DCS正在向着更加开放,更加标准化,更加产品化的方向发展。

作为生产过程自动化领域的计算机控制系统,传统的DCS仅仅是一个狭义的概念。如果以为DCS只是生产过程的自动化系统,那就会引出错误的结论,因为现在的计算机控制系统的含义已被大大扩展了,它不仅包括过去DCS中所包含的各种内容,还向下深入到了现场的每台测量设备、执行机构,向上发展到了生产管理,企业经营的方方面面。传统意义上的DCS现在仅仅是指生产过程控制这一部分的自动化,而工业自动化系统的概念,则应定位到企业全面解决方案,即total solution 的层次。只有从这个角度上提出问题并解决问题,才能使计算机自动化真正起到其应有的作用。

DCS具有以下特点:

(1)高可靠性。由于DCS将系统控制功能分散在各台计算机上实现,系统结构采用容错设计,因此某一台计算机出现的故障不会导致系统其他功能的丧失。此外,由于系统中各台计算机所承担的任务比较单一,可以针对需要实现的功能采用具有特定结构和软件的专用计算机,从而使系统中每台计算机的可靠性也得到提高。

(2)开放性。DCS采用开放式,标准化、模块化和系列化设计,系统中各台计算机采用局域网方式通信,实现信息传输,当需要改变或扩充系统功能时,可将新增计算机方便地连入系统通信网络或从网络中卸下,几乎不影响系统其他计算机的工作。

错误!未指定书签。DCS的发展历史

DCS是分布式控制系统的英文缩写(Distributed Control System),在国内自控行业又称之为集散控制系统。

它是一个由过程控制级和过程监控级组成的以通信网络为纽带的多级计算

机系统,综合了计算机(Computer)、通讯(Communication)、显示(CRT)和控制(Control)等4C技术,其基本思想是分散控制、集中操作、分级管理、配置灵活、组态方便。)

它的发展大体分为三个阶段。

第一阶段:1975-1980年,在这个时期集散控制系统的技术特点表现为:1)采用微处理器为基础的控制单元,实现分散控制,有各种各样的算法,通过组态独立完成回路控制,具有自诊断功能

2)采用带CRT显示器的操作站与过程单元分离,实现集中监视,集中操作3)采用较先进的冗余通信系统

第二阶段:1980—1985.,在这个时期集散控制系统的技术特点表现为:

1)微处理器的位数提高,CRT显示器的分辨率提高

2)强化的模块化系统

3)强化了系统信息管理,加强通信功能

第三阶段,1985年以后,集散系统进入第三代,其技术特点表现为:

1)采用开放系统管理

2)操作站采用32位微处理器

3)采用实时多用户多任务的操作系统

进入九十年代以后,计算机技术突飞猛进,更多新的技术被应用到了DCS 之中。PLC是一种针对顺序逻辑控制发展起来的电子设备,它主要用于代替不灵活而且笨重的继电器逻辑。现场总线技术在进入九十年代中期以后发展十分迅猛,以至于有些人已做出预测:基于现场总线的FCS将取代DCS成为控制系统的主角。

DCS是 Data Communication Subsystem (数据通信子系统)的简称。

以轨道交通行业为例,DCS是一个纯透明的非安全性系统,他是控制中心和列车之间发送报文的载体。

DCS第二层涵义:Dorsal Column Stimulator[医]脊柱刺激器

在特殊控制领域,如核电站控制系统,DCS的含义为数字化控制系统(Digital control system)。

国内DCS主要厂家有:上海新华,鲁能控制,国电智深,浙大中控,和利时,上海华文,上海乐华,浙江中自等。国外的有西屋(艾默生)、FOXBORO、ABB、西门子、霍尼韦尔、横河、山武-霍尼韦尔公司、FISHER-ROSEMOUNT公司等错误!未指定书签。DCS特点和发展概述

DCS是分散控制系统(Distributed Control System)的简称,国内一般习惯称为集散控制系统。它是一个由过程控制级和过程监控级组成的以通信网络为纽带的多级计算机系统,综合了计算机(Computer)、通讯(Communication)、显示(CRT)和控制(Control)等4C技术,其基本思想是分散控制、集中操作、分

级管理、配置灵活、组态方便。

DCS具有以下特点:

(1)高可靠性由于DCS将系统控制功能分散在各台计算机上实现,系统结构采用容错设计,因此某一台计算机出现的故障不会导致系统其它功能的丧失。此外,由于系统中各台计算机所承担的任务比较单一,可以针对需要实现的功能采用具有特定结构和软件的专用计算机,从而使系统中每台计算机的可靠性也得到提高。

(2)开放性 DCS采用开放式、标准化、模块化和系列化设计,系统中各台计算机采用局域网方式通信,实现信息传输,当需要改变或扩充系统功能时,可将新增计算机方便地连入系统通信网络或从网络中卸下,几乎不影响系统其他计算机的工作。

(3)灵活性通过组态软件根据不同的流程应用对象进行软硬件组态,即确定测量与控制信号及相互间连接关系、从控制算法库选择适用的控制规律以及从图形库调用基本图形组成所需的各种监控和报警画面,从而方便地构成所需的控制系统。

(4)易于维护功能单一的小型或微型专用计算机,具有维护简单、方便的特点,当某一局部或某个计算机出现故障时,可以在不影响整个系统运行的情况下在线更换,迅速排除故障。

(5)协调性各工作站之间通过通信网络传送各种数据,整个系统信息共享,协调工作,以完成控制系统的总体功能和优化处理。

(6)控制功能齐全控制算法丰富,集连续控制、顺序控制和批处理控制于一体,可实现串级、前馈、解耦、自适应和预测控制等先进控制,并可方便地加入所需的特殊控制算法。 DCS的构成方式十分灵活,可由专用的管理计算机站、操作员站、工程师站、记录站、现场控制站和数据采集站等组成,也可由通用的服务器、工业控制计算机和可编程控制器构成。处于底层的过程控制级一般由分散的现场控制站、数据采集站等就地实现数据采集和控制,并通过数据通信网络传送到生产监控级计算机。生产监控级对来自过程控制级的数据进行集中操作管理,如各种优化计算、统计报表、故障诊断、显示报警等。随着计算机技术的发展,DCS可以按照需要与更高性能的计算机设备通过网络连接来实现更高级的集中管理功能,如计划调度、仓储管理、能源管理等。

错误!未指定书签。DCS 在国内外的发展与应用状态

1975 年美国最大的仪表控制公司Honeyw ell 首次向世界推出了它的综合分散控制系统TDC—2000 ( Toal D ist ribu ted Con t ro l -2000) , 这一系统的发表, 立即引起美国工业控制界高度评价, 称之为“最鼓舞人心的事件”。世界各国的各大公司也纷纷仿效, 推出了一个又一个集散系统, 从此过程控制进入了集散系统的新时期。

在此期间有日本横河公司推出的CEN TUM , 美国泰勒仪表公司的MO SË , 费雪尔公司的DCÉ —400, 贝利公司的N —90, 福克斯波罗公司的Cpect rum 和德国西门子公司的Telepermm。

随着计算机特别是微型计算机与网络技术的飞速发展, 加上各制造商的激烈竞争, 使DCS 很快从70 年代的第一代发展到90 年代初的第三代DCS。尽管在这之前的集散系统的技术水平已经很高, 但其中存在着一个最主要的弊病是: 各大公司推出的几十种型号的系统, 几乎都是本公司的专利产品, 每个公司为了保护自身的利益, 采用的都是专利网络, 这就为全厂、全企业的管理带来问题。

随着计算机的发展与网络开发使各控制厂商更多地采用商业计算机的技术, 80年代末许多公司推出新一代的集散系统, 其主要特征是新系统的局部网络采用MA P 协议; 引用智能变送器与现场总线结构; 在控制软件上引入PLC 的顺序控制与批量控制, 使DCS 也具有PLC 的功能。

至90 年代初各国知名的DCS 有:3000, Bailey 的IN F I—90,Ro semoun t 的RS—3, W est Hoo se 的WDPF, L eeds &Non th rup 的MAX—1000,Foxbo ro 的IöA S,日本横河的CEN TUM。这里所提到的均为大型的DCS, 为了适应市场的需要各厂商也开发了不少中小型的DCS 系统如S—9000,MAX—2, LXL ,A 2 PACS 等等。

目前国内DCS主要有:新华XDPS,鲁能的LN2000,国电智深DCS,中控DCS,和利时DCS,南京科远DCS,浙江中自等。国外的有西屋(艾默生)ovation、FOXBORO、ABB、西门子PCS7、霍尼韦尔、横河DCS等。

英文翻译

DCS

DCS Distributed Control System is the abbreviation of (Distributed Control System), automation industry in the country is also known as distributed control system.

The so-called distributed control system, or in some of the information in the call distribution system, as opposed to centralized control systems, a new computer control system, which is a centralized control system based on the development, evolution and come. It is a process by the process control level and the composition of monitoring level communications network as a link to the multi-level computer systems, integrated computer, communication, display and control technologies such as 4C, the basic idea is decentralized control, centralized operations, hierarchical management , flexible configuration, and configuration easy. Function in the system,

DCS, and centralized control systems are not very different, but in the realization of system functions methods are completely different.

First, DCS's skeleton - the system network, which is the foundation and core DCS. As the network of the system for real-time DCS, reliability and scalability, play a decisive role, so the manufacturers have been careful in this area of design. For the DCS system network, it must meet the requirements of real-time, that is completed within defined time limits transmission of information. Here the word "determine" the time limit is in any case, the information transfer can be completed within this time limit, and this time limit is based on real-time controlled process requirements identified. Therefore, indicators of network performance measurement system is not the network's rate, known as bits per second (bps), but the real-time system network, which can ensure the long period of time to complete the required information transmission . System network also must be very reliable in any case, network communications are not interrupted, so most manufacturers of DCS were double bus, ring or dual star network topology. Scalability to meet the requirements of the system, the system can access the network should be higher than the maximum number of nodes in the large number of nodes actually used several times. In this way, one can always add a new node, it can also make the system run in a lighter network traffic load conditions, to ensure that the system real-time and reliability. During the actual operation of the system, each node of the Internet and the net may occur at any time, in particular, operator stations, so that reconfiguration will always be, and this operation must not affect the normal operation, therefore, the system network should have a strong online network reconfiguration functions.

Secondly, this is a completely on-site I / O processing and realization of direct digital control (DDC) feature of network nodes. To set the general scene in a DCS I / O controllers, to share the entire system I / O and control functions. This site can be avoided due to a failure caused by the failure of the entire system, improve system reliability, the site also allows sharing of data acquisition and control functions, will help improve overall system performance. DCS operator station is run operation to deal with all the human-machine interface (HMI-Human Machine Interface, or operator interface) function of network nodes.

DCS engineer station is off-line configuration, the system configuration work, and online monitoring, control, maintenance of the network node, and its main function is to provide to the DCS configuration, software configuration tool (ie, the configuration software) and running online in real time DCS DCS network to monitor the operation of each node, the system engineer can engineer station to adjust the system

configuration settings and some system parameters, the DCS at any time under the best working condition. And centralized control systems, are required to have all of the DCS system configuration functions, it can be said, no system configuration functions of the system can not be called as a DCS.

DCS since its inception in 1975, has already experienced twenty years of development. In two decades, DCS system architecture although there is no significant change, but through constant development and improvement of its functionality and performance have been a huge increase. In general, DCS is toward more open, more standardized product in the direction of development.

As the field of process automation computer control system, the traditional DCS is only a narrow concept. If only the production process that DCS automation system, which will lead to wrong conclusions, because the meaning of the computer control system has been greatly expanded, and it includes not only the DCS in the past included a variety of content, but also drill down to the each site measuring equipment, implementing agencies, upwards to the production management, all aspects of business. Traditional DCS now only refers to this part of the production process control automation, and industrial automation system concept, should be targeted to enterprise-wide solution, total solution level. Only from this perspective to ask questions and solve problems, to really play the computer automation of its role.

DCS has the following characteristics:

(1) high reliability. DCS system to control the spread of the computer implementation, the system uses fault-tolerant design of the structure, so a computer system malfunction will not cause the loss of other functions. In addition, each computer system, the tasks undertaken by relatively simple functions can be used for the need to achieve a specific structure and special computer software, so that the reliability of each computer system has also been improved.

(2) open. DCS an open, standardized, modular and serial design, the system means each computer using the LAN communication, to achieve information transmission, when the need to change or expand the system functionality can be added easily connected to a computer system communication network or Remove from the network, almost does not affect the work of other computer systems.

History of development of DCS

DCS Distributed Control System is the abbreviation of (Distributed Control System), automation industry in the country is also known as distributed control system.

It is a process by the process control level and the composition of monitoring level

communications network as a link to the multi-level computer systems, integrated computer (Computer), communication (Communication), display (CRT) and control (Control) and other 4C technology, The basic idea is decentralized control, centralized operations, hierarchical management, flexible configuration, easy configuration. )

Its development can be divided into three stages.

Stage :1975-1980, during this period the technical characteristics of distributed control system as follows:

1) using microprocessor-based control unit, to achieve decentralized control, a wide variety of algorithms, through the loop control configuration independently, with self-diagnostic function

2) The operating station with a CRT display unit and the process of separation, centralized monitoring, centralized operation

3) a more advanced communication system redundancy

The second phase :1980-1985., Distributed control system during this period the technical features as follows:

1) increase the number of bits microprocessors, CRT display resolution to improve

2) strengthening the modular system

3) strengthen the system of information management, strengthening communication The third phase, after 1985, the third generation of distributed systems, and its technical characteristics were as follows:

1) The adoption of open systems management

2) 32-bit microprocessor operating station

3) using real-time multi-user multi-tasking operating system

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.

DCS is a Data Communication Subsystem (data communications subsystems) for short.

To rail transportation industry, for example, DCS is a pure non-transparent security system, he is sent between the control center and train carrier packet.

DCS second layer of meaning: Dorsal Column Stimulator [medical] spine stimulator In the special control areas, such as nuclear power plant control system, DCS is the meaning of digital control system (Digital control system).

DCS main domestic manufacturers are: Shanghai Xinhua, the super control, State Power Zhishen, Zhejiang University in control, and Belgium, Shanghai Chinese, Shanghai Leroy, from Zhejiang and so on. There Westinghouse abroad (Emerson), FOXBORO, ABB, Siemens, Honeywell, Yokogawa, Yamatake - Honeywell, FISHER-ROSEMOUNT companies

Overview of characteristics and development of DCS

DCS is a distributed control system (Distributed Control System) for short, is commonly called the domestic general distributed control system. It is a process by the process control level and the composition of monitoring level communications network as a link to the multi-level computer systems, integrated computer (Computer), communication (Communication), display (CRT) and control (Control) technologies such as 4C, the The basic idea is decentralized control, centralized operations, hierarchical management, flexible configuration, easy configuration. DCS has the following characteristics:

(1) high reliability of the DCS system to control the spread of the computer implementation, the system uses fault-tolerant design of the structure, so a computer system malfunction will not cause the loss of other functions. In addition, each computer system, the tasks undertaken by relatively simple functions can be used for the need to achieve a specific structure and special computer software, so that the reliability of each computer system has also been improved.

(2) DCS open an open, standardized, modular and serial design, the system uses the computer local area network communication means to achieve information transmission, when the need to change or expand the system functionality can be added easily with a computer communication network into the system or removed from the network, almost does not affect the work of other computer systems.

(3) flexibility in the configuration software through the process of application objects according to different hardware and software configuration, which determine the measurement and control signals and inter-connection of the control algorithms from the library and select the appropriate control law called from the basic graphic components graphic library required for various monitoring and alarm screen, thus easily constitute the required control system.

(4) easy maintenance features a single small or micro-dedicated computer, with easy maintenance, convenient features, and when a local or a computer failure, you can run the system without affecting the case of line replacement, rapid troubleshooting . (5) coordination between the various stations of various data transmission through the

communication network, the whole system of information sharing, coordination of work to complete the control system's overall functionality and optimization.

(6) control functional control algorithm rich set of continuous control, sequence control and batch control in one, can be realized cascade, feedforward, decoupling, adaptive and predictive control, advanced control, and easily add the necessary Special control algorithms. The composition of DCS approach is flexible, managed by a dedicated computer stations, operator stations, engineering stations, recording station, site controller and data acquisition stations and other components, but also by a common server, industrial computer and programmable controller was. At the bottom of the process control level are generally distributed on-site controllers, data acquisition stations, data acquisition and control in place, and through the data communications network to monitor and control level computer. Production control level on the data from the process control level centralized operations management, such as various optimization, statistical reports, fault diagnosis, alarm and so on. With the development of computer technology, DCS can follow a more high-performance needs and computer equipment connected through the network to achieve more advanced centralized management features, such as planning and scheduling, warehouse management, energy management.

DCS in the development and application of state at home and abroad

In 1975, the largest U.S. companies Honeyw ell instrument control to the world launched its first integrated distributed control system TDC-2000 (Toal D ist ribu ted Con t ro l -2000), published in the system, immediately aroused the U.S. industrial control community highly, calling it "the most inspiring event." Major companies around the world quickly followed, introduced one by one distribution system, from process control to enter a new era of distributed systems.

During this period the Japanese Yokogawa introduced CEN TUM, the United States Taylor Instrument Company MO S?, Fischer's DCé-400, Bailey's N -90, Foxboro Cpect rum and the German company Siemens Company Telepermm.

With micro-computer and computer networks in particular, the rapid development of technology, coupled with fierce competition of the manufacturers, so that DCS quickly from the first generation of the 70s to the early 90s the development of the third generation of DCS. Although distribution systems before that the technical level is already high, but there is a major drawback is: the major companies introduced dozens of models of the system, almost all of the company's patented product, each company in order to protect their own interests, patents are used in the network, which

英文文献翻译

中等分辨率制备分离的 快速色谱技术 W. Clark Still,* Michael K a h n , and Abhijit Mitra Departm(7nt o/ Chemistry, Columbia Uniuersity,1Veu York, Neu; York 10027 ReceiLied January 26, 1978 我们希望找到一种简单的吸附色谱技术用于有机化合物的常规净化。这种技术是适于传统的有机物大规模制备分离,该技术需使用长柱色谱法。尽管这种技术得到的效果非常好,但是其需要消耗大量的时间,并且由于频带拖尾经常出现低复原率。当分离的样本剂量大于1或者2g时,这些问题显得更加突出。近年来,几种制备系统已经进行了改进,能将分离时间减少到1-3h,并允许各成分的分辨率ΔR f≥(使用薄层色谱分析进行分析)。在这些方法中,在我们的实验室中,媒介压力色谱法1和短柱色谱法2是最成功的。最近,我们发现一种可以将分离速度大幅度提升的技术,可用于反应产物的常规提纯,我们将这种技术称为急骤色谱法。虽然这种技术的分辨率只是中等(ΔR f≥),而且构建这个系统花费非常低,并且能在10-15min内分离重量在的样本。4 急骤色谱法是以空气压力驱动的混合介质压力以及短柱色谱法为基础,专门针对快速分离,介质压力以及短柱色谱已经进行了优化。优化实验是在一组标准条件5下进行的,优化实验使用苯甲醇作为样本,放在一个20mm*5in.的硅胶柱60内,使用Tracor 970紫外检测器监测圆柱的输出。分辨率通过持续时间(r)和峰宽(w,w/2)的比率进行测定的(Figure 1),结果如图2-4所示,图2-4分别放映分辨率随着硅胶颗粒大小、洗脱液流速和样本大小的变化。

最新和利时dcs介绍

和利时d c s介绍

DCS系统概述 一、过程控制系统的发展历程 早期的控制系统往往是一台二次仪表控制一个回路,各回路的仪表相互之间没有关联关系,单个回路的仪表损坏之后并不影响其他回路仪表的正常运行。 第一代过程控制系统(PCS,Pneumatic Control System)是基于气信号的气动仪表控制系统; 第二代过程控制系统(ACS,Analogous Control System)是基于模拟电流信号的电动模拟单元组合式仪表控制系统; 20世纪80年代,微处理机的出现和应用,从而产生了分布式控制系统,即第三代过程控制系统(DCS,Distributed Control System); 20世纪90年代,现场总线技术的出现产生了新的一代过程控制系统,即现场总线控制系统FCS(Fieldbus Control System) 。 DCS即集散型控制系统,又称分布式控制系统(Distributed Control System)。它是指利用计算机技术将所有的二次显示仪表集中在电脑上显示,同时所有的一次表及调节阀等仍然分散安装在生产现场,DCS系统的核心是布置在机柜室的现场控制站,一旦控制站出现出现故障,将会导致灾难性的后果,为了避免这种情况的发生,各DCS生产厂家采用在线冗余(如同机泵的备用泵一样,一台坏了,另一台自动运行,而且是无扰动的切换。在这种切换方式下,我们人根本感觉不到任何变化发生)的技术来解决这一问题。 DCS系统的主要基础是4C技术,即计算机-Computer、控制-Control、通信-Communication和CRT显示技术。

DCS系统通过某种通信网络(如以太网、总线等)将分布在工业现场的现场控制站和操作室(控制中心)的操作员站及工程师站等连接起来,以完成对现场生产设备的分散控制和集中操作管理(工程师站与操作站一样都是普通的计算机,只是因为其内部装有组态软件而已,大多数情况下工程师站也能作为操作站使用)。 下图以一个水位信号调节的例子简单地说明DCS系统在实际生产中的应用过程: 被控对象(过程):工艺生产设备(如反应釜,换热器,汽包、水箱等),从传感器(测量变送单元)到执行器之间。 被控参数:各种工艺参数,如液位,温度,压力等。 测量变送:对被控参数进行测量转换的装置(转换成标准信号)。 调节器:把测定值和设定值进行比较和运算并输出控制信号的装置。 执行器(调节阀):接收调节器来的信号并予以执行的装置。 我们可以把上述过程引申如下:

文献综述,外文翻译,论文网站

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DCS系统简介

百科名片 DCS是分布式控制系统的英文缩写(Distributed Control System),在国内自控行业又称之为集散控制系统。即所谓的分布式控制系统,或在有些资料中称之为集散系统,是相对于集中式控制系统而言的一种新型计算机控制系统,它是在集中式控制系统的基础上发展、演变而来的。它是一个由过程控制级和过程监控级组成的以通信网络为纽带的多级计算机系统,综合了计算机,通信、显示和控制等4C技术,其基本思想是分散控制、集中操作、分级管理、配置灵活以及组态方便。 基本介绍 首先,DCS的骨架—系统网络,它是DCS的基础和核心。由于网络对于DCS整个系统的实时性、可靠性和扩充性,起着决定性的作用,因此各厂家都在这方面进行了精心的设计。对于DCS的系统网络来说,它必须满足实时性的要求,即在确定的时间限度内完成信息的传送。这里所说的“确定”的时间限度,是指在无论何种情况下,信息传送都能在这个时间限度内完成,而这个时间限度则是根据被控制过程的实时性要求确定的。因此,衡量系统网络性能的指标并不是网络的速率 DCS ,即通常所说的每秒比特数(bps),而是系统网络的实时性,即能在多长的时间内确保所需信息的传输完成。系统网络还必须非常可靠,无论在任何情况下,网络通信都不能中断,因此多数厂家的DCS均采用双总线、环形或双重星形的网络拓扑结构。为了满足系统扩充性的要求,系统网络上可接入的最大节点数量应比实际使用的节点数量大若干倍。这样,一方面可以随时增加新的节点,另一方面也可以使系统网络运行于较轻的通信负荷状态,以确保系统的实时性和可靠性。在系统实际运行过程中,各个节点的上网和下网是随时可能发生的,特别是操作员站,这样,网络重构会经常进行,而这种操作绝对不能影响系统的正常运行,因此,系统网络应该具有很强在线网络重构功能。其次,这是一种完全对现场I/O处理并实现直接数字控制(DDC)功能的网络节点。一般一套DCS中要设置现场I/O控制站,用以分担整个系统的I/O和控制功能。这样既可以避免由于一个站点失效造成整个系统的失效,提高系统可靠性,也可以使各站点分担数据采集和控制功能,有利于提高整个系统的性能。DCS的操作员站是处理一切与运行操作有关的人机界面(HMI-Human Machine Interface或operator interface)功能的网络节点。工程师站是对DCS进行离线的配置、组态工作和在线的系统监督、控制、维护的网络节点,其主要功能是提供对DCS进行组态,配置工作的工具软件(即组态软件),并在DCS在线运行时实时地监视DCS网络上各个节点的运行情况,使系统工程师可以通过工程师站及时调整系统配置及一些系统参数的设定,使DCS随时处在最佳的工作状态之下。与集中式控制系统不同,所有的DCS都要求有系统组态功能,可以说,没有系统组态功能的系统就不能称其为DCS。DCS自1975年问世以来,已经经历了三十多年的发展历程。在这三十多年中,DCS虽然在系统的体系结构上没有发生重大改变,但是经过不断的发展和完善,其功能和性能都得到了巨大的提高。总的来说,DCS正在向着更加开放,更加标准化,更加产品化的方向发展。作为生产过程自动化领域的计算机控制系统,传统的DCS仅仅是一个狭义的概念。如果以为DCS只是生产过程的自动化系统,那就会引出错误的结论,因为现在的计算机控制系统的含义已被大大扩展了,它不仅包括过去DCS 中所包含的各种内容,还向下深入到了现场的每台测量设备、执行机构,向上发展到了生产管理,企业经营的方方面面。传统意义上的DCS现在仅仅是指生产过程控制这一部分的自动化,而工业自动化系统的概念,则应定位到企业全面解决方案,即total solution 的层次。

计算机网络-外文文献-外文翻译-英文文献-新技术的计算机网络

New technique of the computer network Abstract The 21 century is an ages of the information economy, being the computer network technique of representative techniques this ages, will be at very fast speed develop soon in continuously creatively, and will go deep into the people's work, life and study. Therefore, control this technique and then seem to be more to deliver the importance. Now I mainly introduce the new technique of a few networks in actuality live of application. keywords Internet Network System Digital Certificates Grid Storage 1. Foreword Internet turns 36, still a work in progress Thirty-six years after computer scientists at UCLA linked two bulky computers using a 15-foot gray cable, testing a new way for exchanging data over networks, what would ultimately become the Internet remains a work in progress. University researchers are experimenting with ways to increase its capacity and speed. Programmers are trying to imbue Web pages with intelligence. And work is underway to re-engineer the network to reduce Spam (junk mail) and security troubles. All the while threats loom: Critics warn that commercial, legal and political pressures could hinder the types of innovations that made the Internet what it is today. Stephen Crocker and Vinton Cerf were among the graduate students who joined UCLA professor Len Klein rock in an engineering lab on Sept. 2, 1969, as bits of meaningless test data flowed silently between the two computers. By January, three other "nodes" joined the fledgling network.

变电站_外文翻译_外文文献_英文文献_变电站的综合概述

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