集散控制系统(DCS)简介.doc

Distributed Control SystemTotal Distributed control system is based on multiplemicroprocessors based on the use of modern network technology, modern control technology, graphics technology and redundancy technology to achieve the object of the regulation ofdecentralized control, monitoring, management, control technology. Characterized by decentralized control based on decentralized control of the object to adapt in order to focus on surveillance and control operations to achieve overall objectives. System has high stability, reliability and scalability.Distributed control systems are generally composed of four parts: (1) process input and output devices; (2) process control device; (3) operation interface; (4) data communication systems.The drive toward openness in the 1980s gained momentum through the 1990s with the increased adoption of Commercial off-the-shelf (COTS) components and IT standards. Probably the biggest transit ion undertaken during this time was the move from the UNIX operat- ing system to the Windows environment. While the realm of the real time operating system (RTOS) for control applications remains dom- inated by real time commercial variants of UNIX or proprietary op- erating systems, everything above real-time control has made the transition to Windows.The introduction of Microsoft at the desktop and server layers resulted in the development of technologies such as OLE for Proce- ss Control (OPC), which is now a de facto industry connectivity standard. Internet technology also began to make its mark in auto- mation and the DCS world, with most DCS HMI supporting Internet connectivity. The 90s were also known for the Fieldbus Wars, where rival organizations competed to define what would become the IEC fieldbus standard for digital communication with field instru- mentation instead of 4-20 milliamp analog communications. The first fieldbus installations occurred in the 1990s. Towards the end of the decade, the technology began to develop significant momentum, with the market consolidated around Foundation Fieldbus and Profibus PA for process automation applications. Some suppliers built new systems from the ground up to maximize functionality with fieldbus, such as ABB with System 800xA6, Emerson Process Management7 with the DeltaV control system, Siemens8 with the Simatic PCS79 and azbil10 from Yamatake with the Harmonas-DEO system.The impact of COTS, however, was most pronounced at the hardware layer. For years, the primary business of DCS suppliers had been the supply of large amounts of hardware, particularly I/O and controllers. The initial proliferation of DCSs required the installation of prodigious amounts of this hardware, most of it manufactured from the bottom up by DCS suppliers. Standard computer components from manufacturers such as Intel and Motorola, however, made it cost prohibitive for DCS suppliers to continue making their own components, workstations, and networking hardware.As the suppliers made the transition to COTS components,they also discovered that the hardware market was shrinking fast. COTS not only resulted in lower manufacturing costs for the supplier, but also steadily decreasing prices for the end users, who were also becoming increasingly vocal over what they perceived to be unduly high hardware costs. Some suppliers that were previously stronger in the PLC business, such as Rockwell Automation, Siemens, were able to leverage their expertise in manufacturing control hardware to enter the DCS marketplace with cost effective offerings, while the stability/scalability/reliability and functionality of these emerging systems are still improving. The traditional DCS suppliers introduced new generation DCS System based on the latest Communication and IEC Standards, which resulting in a trend of combining the traditional concepts/functionalities for PLC and DCS into a one for all solution - named Process Automation System. The gaps among the various systems remain at the areas such as: the database integrity, pre-engineering functionality, system maturity, communication transparency and reliability. While it is expected the cost ratio is relatively the same (the more powerful the systems are, the more expensive they will be), the reality of the automation business is often operating strategically case by case. The current next evolution step is called Collaborative Process Automation Systems.To compound the issue, suppliers were also realizing that the hardware market was becoming saturated. The lifecycle of hardware components such as I/O and wiring is also typically in the range of 15 to over 20 years, making for a challenging replacement market. Many of the older systems that were installed in the 1970s and 1980s are still in use today, and there is a considerable installed base of systems in the market that are approaching the end of their useful life. Developed industrial economies in North America, Europe, and Japan already had many thousands of DCSs installed, and with few if any new plants being built, the market for new hardware was shifting rapidly to smaller, albeit faster growing regions such as China, Latin America, and Eastern Europe.Distributed Control System, also known as distributed control system, as opposed to centralized control system for the purposes of a new computer control system, which is a centralized control system based on the development of evolved. Function in the system, DCS, and centralized control system is little different, but in the realization of system function method is entirely different. First of all, DCS skeleton - system network, which is the foundation and core of DCS. As the network for the DCS system-wide real-time, reliability and scalability, play a decisive role, so that the manufacturers have carried out carefully in this design. For the DCSs system network, it must meet the requirements of real-time, that is completed within defined time limits transmission of information. By OK time limit, that means no matter the circumstances, the information transmission can be completed within this time limit, and this time limit is to be controlled according to the process of real-time requirements determined. Therefore, indicators of network performance measurement system is not the network speed,known as bits per second (bps), but the system network of real-time, that is able to multi-long period of time to ensure that the transmission of the information needed to complete . System network is also to be very reliable in any case, the network communication can not be interrupted, so most manufacturers have adopted DCS dual-bus, ring, or double star-shaped network topology. In order to meet the requirements of the system scalability, the system on the network can access the maximum number of nodes should be compared with the large number of nodes actually used several times. In this way, on the one hand can always add new nodes, it can also make the system run on less communication network load conditions, in order to ensure that the system of real-time and reliability. In the system during the actual operation, each node in the Internet and the next network is always possible, especially in the operator station, so that network reconfiguration will be conducted regularly, and this operation is absolutely not affect the normal operation of the system, therefore, the system the network should have a strong online network reconfiguration functions. Secondly, it is a completely on-site I / O processing and realization of direct digital control (DOS) function of network nodes. To set up a general set of DCS in the field I / O controllers, to share the whole system I / O and control functions. This will not only avoid the site because of a failure caused by failure of the entire system, improve system reliability, you can also enable the site to share data acquisition and control functions, helping improve overall system performance. DCS operator station is run operations to deal with all the relevant human-machine interface (HMI-Human Machine Interface, or operator interface) function of network nodes. System network is a DCS engineer station, which is off-line DCS configuration, the configuration of the system of work and on-line, control, maintenance of network nodes, its main function is to provide for the configuration of the DCS, configuration tools to work (ie, configuration software), and DCS-line real-time monitor run time on the network each node DCS operation, allowing the system engineers by engineers to stop in time to adjust the system configuration and some system parameters set, so that at any time in the DCS under good working condition. With centralized control systems, all of the DCS are required to have system configuration functions, can be said that there is nosystemconfigurationfunction of the system can not be called DCS.集散控制系统(DCS)集散控制系统是以多个微处理机为基础利用现代网络技术、现代控制技术、图形显示技术和冗余技术等实现对分散控制对象的调节、监视管理的控制技术。其特点是以分散的控制适应分散的控制对象，以集中的监视和操作达到掌握全局的目的。系统具有较高的稳定性、可靠性和可扩展性。集散控制系统一般有四部分组成：（1）过程输入输出装置；（2）过程控制装置；（3）操作接口；（4）数据通讯系统。走向20世纪80年代开放驱动器中获得了20世纪90年代与商业越来越多地采用过的势头现货（COTS）的组件和IT标准。也许最大的过渡过程，在这个时候进行的是从UNIX操作系统迁移到Windows环境。而实时操作系统控制应用（RTOS）的领域仍然受到实时或专有的UNIX操作系统，上面实时控制主宰一切商业变种已到Windows的过渡。 这方面，微软在台式机和服务器层引入导致了技术的发展，如过程控制（OPC），现在已成为一种事实上的工业标准的OLE连接。互联网技术也开始发挥影响，在自动化和区议会的世界，大多数DCS人机界面支持互联网连接。九十年代，又称为的“现场总线大战”，在那里比赛的对手组织界定什么将成为国际电工委员会与外地，而不是4-20毫安的模拟通信仪器数字通信现场总线标准。现场总线安装的第一个发生在20世纪90年代。在接近2010年底，这项技术开始发展的重要力量，与周围基金会现场总线和Profibus PA巩固了流程自动化应用市场。一些供应商从底层建立新体制，最大限度地获得如ABB现场总线与系统800xA功能6，艾默生过程管理同的DeltaV控制系统，西门子8 7与西门子Simatic PCS 7的9和azbil 10武与Harmonas，教育署各分区系统。 在COTS的影响，但是，最明显的硬件层。多年来，集散控制系统供应商的主要业务一直是大量的硬件，供应，特别是I / O和控制器。最初的DCSs增殖所需的这些硬件的安装数量惊人，其中大部分来自由下而上，由DCS供应商生产的。计算机制造商的标准组件，如英特尔和摩托罗拉，然而，使成本DCS供应商望而却步，继续作出自己的组件，工作站和网络硬件。 由于供应商的向COTS组件的过渡，他们还发现，硬件市场快速萎缩。现成不仅造成对供货商降低生产成本，但对最终用户，谁也正成为越来越强的麻烦，他们认为是过高的硬件成本价格也持续下降。一些供应商，以前强于临业务，如罗克韦尔自动化，西门子，能够充分发挥其在制造控制硬件，进入成本效益的产品的集散市场的专门知识，而稳定/可扩展性/可靠性和这些新兴功能系统仍然改善。传统的DCS供应商推出的新一代DCS系统基于最新的通信和IEC标准，这是传统观念相结合的趋势/为PLC和DCS功能造成转变为支持全方位的解决方案之一-名为“过程自动化系统”。各系统之间的差距继续存在，如：在地区的数据库的完整性，预工程的功能，系统的成熟程度，沟通的透明度和可靠性。虽然预期的成本的比例是比较相同的（更强大的系统，较昂贵的，他们会）的自动化商业现实经营战略往往是逐案。目前的下一个演进步骤是所谓的协作过程自动化系统。 雪上加霜的问题，供应商也意识到，硬件市场已渐趋饱和。如我生命周期的硬件组件/ O和电线也通常在15范围内超过20年，更换为一个具有挑战性的市场决策。老一辈的人在20世纪70年代和80年代安装的系统，许多人目前仍在使用，并存在着相当大的安装基础，在市场上的系统，已接近其使用寿命结束。在北美，欧洲，日本等先进工业国家已经安装DCSs成千上万，以及几乎没有新厂正在兴建，对新硬件的市场迅速转向更小，虽然快速增长的中国，拉美地区和东欧。 集散控制系统也叫分布式控制系统，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。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（DOS）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oper