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控制系统设计 造纸集散控制系统 集散控制系统

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造纸碱回收分布式控制系统设计,控制系统设计,造纸集散控制系统,集散控制系统

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Distributed Control systemDistributed Control system(DCS) is disperses the control system take the microprocessor as the foundation centralism. Since the 70s intermediate stage first set of collection and distribution control system being published, Distributed Control system already obtained the widespread application in the industry control domain.Distributed Control system principal characteristic is its centralized management and the disperser control. Moreover, along with the computer technology development, the networking already caused Distributed Control system mainly to use in dispersing the control, and turned towards the direction of the integrated management to develop. Not only the system opening enables the different manufacture manufacturer Distributed Control system product to be possible the interconnection, moreover causes them to be possible to carry on the data conveniently the exchange, the system opening also enables the third party the software to be possible to apply conveniently on the existing collection and distribution control system. Petrifies the profession in our country to move many set of different model collections and distributions and the control system, they are playing the extremely vital role in the process control.1Development historyDistributed Control system was in 1975 first Corporation promotes by American Huo Nepali Will (Honeywell). Because at that time in the process industry control application used the simulation electrically operated measuring appliance control system to solve the related control problem with difficulty, used the computer the direct digital control also with difficulty to overcome, they were:(1)The production process scale unceasing expansion causes the master control room measuring appliance quantity to be more and more many, the operator more and more is also high to the process surveillance and the operation request, the original simulation measuring appliance is competent with difficulty.(2)The measuring appliance technology and other high technology and new technologies are the same, the development speed is very quick, the renewal cycle is more and more short, the industrial technology development requests the measuring appliance control system to be able to meet their need to develop.(3)At that time the computer already started in the industry control domain to apply, it had the numerical control algorithm caused the control system the implementation to become convenient, the change extremely was also easy. But, because its price is very expensive, uses is the direct digital control or the surveillance computer control, because therefore creates the computer breakdown the harm reduces, causes the danger to be dispersible, becomes the application computer control system most important solution the question.(4)The centralism and the synthesis operation and the surveillance request to the entire factory, various workshops and the construction section level control and the operation have the corresponding data communication relation, not only it the request has the massive data transmission, also requests to have the high speed data transmission speed.Honeywell Corporations TDC-2000 is precisely in this case promotes. At that time DCS also in newly established stage, product or collection and distribution control system embryonic form. But the system has already included the DCS three big constituent, namely disperser operating controls, operation management installment and data communication system. It also had the DCS essential feature, namely centralized management, disperser control.Along with high technology and new technology and so on Semiconductor Technology, demonstration technology, control technology, networking and software technology development, Distributed Control system also obtained the rapid development. The second generation of collection and distribution control system main characteristic is the system function expands or the enhancement. For example, control algorithm expansion. The conventional control and the logical control, the batch control unifies; Process operation management scope expansion, function addition and so on. But an obvious change is the data communication system development, transforms from the host from the type quantity shape network correspondence into to the equality main line network correspondence or the ring net correspondence. But, various factories communications system does things their own way, corresponds existence certain difficulty in the different factory collection and distribution control system between. In the second generation of collection and distribution control system, the communications system has used the confined network, therefore, the system communication range expands, simultaneously the data transmission speed also greatly enhances.American Foxboro Corporation I/which promotes in 1987.The AS system symbolized Distributed Control system entered the third generation. Its main change is in the confined network aspect, I/The AS system has used 10 megabits/Second broadband networks and 5 megabits/Moves carries the belt net, conforms to the international standard to organize ISO the OSI open system interconnection reference model. Therefore, in conforms to between the open system various factories product to be possible to connect mutually, to correspond mutually and carries on the data exchange, the third party application software also can apply in the system, thus caused Distributed Control system to enter a higher stage, simultaneously the third generation collection and distribution control system provided the control function also had the enhancement. Usually, the system no longer is the conventional control, the logical control and the batch control synthesis, but increased each kind auto-adapted or the self regulating decides the control algorithm, the user may in to the accusation object characteristic understand in the few situations applies the control algorithm which provides, obtains the good controller parameter by the system automatic scan or through certain operation, therefore the third generation collection and distribution control system has provided the broader application place for the user.2.Basic structureThe three major parts of Distributed Control system are composed by below:(1)Dispersible operating controlsThe dispersible operating controls are Distributed Control system and the production process contact surface, the production process each kind of process variable transform through the disperser operating controls as the operation surveillance data, but operates each kind of information also delivers the implementing agency through the disperser operating controls. In the disperser operating controls, carries on the simulation quantity and the digital quantity interconversion, completes the control algorithm each kind of operation, to inputs carries on the related software filter and its some operations with the output.(2)Operation management installmentThe operation management installment is the operator and contact surface between the collection and distribution control system, the operator through the operation management installment understanding production process movement condition, and sends out the operational order through it to give the production process. Production process each kind of parameter demonstrated in the operation management installment that, is advantageous for the operator surveillance and the operation.(3)Communications systemThe dispersible operating controls and operation between the management installment to need to have a bridge to complete between the data the transmission and the exchange, this is the communications system.Some collection and distribution control system product increased the scene installment level control device and the field bus communications system in the disperser operating controls, some collection and distribution control system product increased the synthesis management level control device and the corresponding communications system in the operation management installment. These collection and distribution control system enable the system the graduation increase, the system communications system to have the different request to the different installment, but, looked from the system total structure, by three major part is composed.3.CharacteristicsDistributed Control system can be that it has by the widespread application reason the fine characteristic. Compares with the simulation electrically operated measuring appliance, it has the connection conveniently, uses the flexible connection the method connection easily to change, the display mode nimbly, the demonstration content diverse, the data reserves big and so on the merits; Compares with the computer common control, it has operates the inspector general conveniently, the danger disperses, merits and so on function disperser. Therefore, it was applied in all the various trades and occupations each domain.(1)Grades the hierarchical controlDistributed Control system is the graduation hierarchical control system. It in the vertical direction and the horizontal direction all is the graduation. The simple collection and distribution control system at least divides into two levels in the vertical direction, namely operation management level and process control level. In the horizontal direction between each process control level is the intercoordination graduation, they the data upward delivery operation management level, the simultaneous reception operation management level instruction, each level graduation also carry on mutually the data the exchange, such system is the graduation hierarchical system. Distributed Control system scale is bigger, the system vertical and the level graduation scope is also broader.Grades the hierarchical system merit is each graduation has respective division of labor scope, between has the coordination mutually, usually, this kind of coordination is completes through the previous graduation. About each graduation relations usually are following graduation deliver this level of and its subordinates graduation data on the level, carries on the coordination by on level according to the production request, and gives the corresponding instruction is the data, through the data communications system, delivers the data the lower level the related graduation. In the collection and distribution control system, the process control level gathering process each kind of data message, transforms them the digital quantity. These data obtain after the computation affect to the implementing agency data output, then, after transforms into the implementing agency the input signal, delivers the implementing agency to go. May see, in the collection and distribution control system, each graduation has respective function, completes respective operation. Between them namely has the division of labor also to have the relation, completes respective task in respective work, simultaneously their inter-coordination, restricts mutually, causing the overall system to move under the optimized operating condition.(2)Disperser controlThe disperser control is Distributed Control system another characteristic, the disperser is aims at the centralism to say. In the computer control system application initial period, the control system is central, namely a computer completes the complete operation surveillance and the process control.Overseas often is called the disperser control system to the collection and distribution control system, namely DCS. Its reason is places the disperser control the extremely important status. Not merely the disperser meaning disperses the control, it has also contained other significances. For example; the personnel disperses, the region disperses, the function disperses, the danger disperses, the equipment disperser and the operation disperser and so on. The disperser goal is in order to causing the danger to be dispersible, enhances the equipment to be possible the use factor.The central computer control system is developed in the master control room common control foundation comes. Because on a computer all process functions and so on information demonstration, record, operation, transformation concentrates in together, also has had a series of questions. Once first is the computer breaks down, will create the process operation the entire line paralysis, for this, the idea which the danger dispersed has raised, the redundant concept also produced. But, must use a same computer control system to take the original system reserve, regardless of technically all is economically invalid. By the computer function analyzing, it indicates that when carries on the disperser in the process control level, the carries on the process control and the operation management the disperser is possible and feasible.Along with the production process scale unceasing expansion, the equipment installment position also more and more disperses, concentrates the wide range in each kind of process parameter to a master control room becomes uneconomical, moreover operates is not convenient. Therefore, the region disperser and personnels disperser has also raised. But personnels disperser also has with the large scale production process management the close relationship. Also the region disperser and personnels disperser requests the computer control system to adapt. In common control computer system, in order to operate convenient, needs to have the display monitor which several operations uses, each operator carries on the operation in respective operation screen, because moves in the identical computer system, the system interrupt priority, the time-sharing operation and so on the request is also high, the system also can appear because of many users interrupt creates the computer the death machine. The operation dispersible and the multi-user multi-advancement computer operation system request has also raised.Through analysis and comparison, the people realized the centralism computer control system insufficient good way to solve the disperser control system. At the same time, in reality, the people also in unceasingly improve the disperser control system the performance, enables it to play the major role in the process control domain.(3)Autonomous and coordinationDistributed Control system each constituent is the autonomous system which does things their own way, they complete respective function respectively, also has the relation mutually, the data message exchanges mutually, each kind of condition restricts mutually, works under the system coordination.In the collection and distribution control system, the dispersible operating controls are an autonomous system, it completes functions and so on data gathering, signal processing, computation and data output. The operation management installment completes the data demonstration, operation surveillance and control signal functions and so on transmission. The communications system completes the operation management to install and to disperse the operating controls the data communication. Distributed Control system various part is respectively the independent autonomous system, but, they also coordinates the work mutually in the system.Because the overall system is an inter-coordination system, therefore, although each constituent is autonomous, but, any partial breakdowns also can to other part of influential. For example, the operation management installment breakdown will cause the operator to be unable to know the process the movement situation; The communications system breakdown can cause the data transfer to make a mistake; The operating controls breakdown causes the system to be unable the normal work. What should point out is that the different part breakdown to the overall system influence size is different. Therefore, when collection and distribution control system shaping and system disposition should consider the important spot establishment compares the redundant reliable part or has the necessity redundant measure and so on.In the collection and distribution control system, the disperser connotation is extremely widespread. The dispersible database, the disperser control function, the disperser data display, the disperser correspondence, the disperser power supply, the disperser load and so on, their disperser is the inter-coordination disperser. Therefore, has the centralism data management, the centralism control goal, centralism screen, centralism communication management and so on, in the disperser for disperses Writers Association to manage well distributed. Each dispersible autonomous system is under the unification centralized management and the coordination respective disperser work.4 The trend of developmentThe field bus is Distributed Control system