Cognitive practice is an indispensable practical link for students majoring in electronic information engineering, an important link to understand the future development of this major, and can lay a foundation for subsequent teaching and graduation. The following is the information engineering paper I brought to you, hoping to help you.
With the gradual improvement of automation control level in electric power enterprises, the expansion of modern industrial process control scale, the increasing complexity and the strengthening of process flow, distributed control system dcs has been widely used in power plants and industrial enterprises.
The use of dcs has greatly improved the safety and stability of unit operation, changed the traditional operation mode and management state in the production process, and achieved remarkable economic and social benefits.
Distributed control system (dcs) is a system which takes microprocessor as the core, adopts data communication technology and crt display technology, and carries out centralized operation management and decentralized control on the production process. It is also called fully distributed control system (tdcs or tdc). Or distributed computer control system (dccs).
Dcs is a new control system developed in the middle of 7X era, which is the product of the combination of 4c technologies (computer, control, communication and crt display). With the development of technology, it is integrated with information management technology. At present, dcs is a modern equipment to complete process control and information management (that is, 5c technology). Distributed control system is a new control system based on the premise of large-scale industrial production process and its increasingly complex control objects, from the perspective of integrated automation of production process, according to the principle of decomposition and coordination in system engineering, with microprocessor as the core, combined with control technology, communication technology and rt display technology. The system has been widely used in process control in various industries, especially in thermal power plants.
Since the advent of 19XX, dcs has undergone four major changes. In 1970s, the hardware, operating system and monitoring software of the operating station were all dedicated and developed by dcs manufacturers themselves, and there was no dynamic flow chart. The communication network is basically polling. In 1980s, communication networks mostly adopted token mode. In 1990s, a universal system appeared in the operating station. At the end of 1990s, some communication networks followed the tcp/ip protocol, and some began to adopt Ethernet. The development of the fourth generation dcs system is mainly reflected in its more integrated functions, including process control, logic control and batch control, realizing mixed control and further decentralization. Honeywell's latest experion pks (Process Knowledge System), Emerson's Plant Web (Emerson Process Management), foxboro's a2, Yokogawa's r3(prm- Factory Resource Management System) and abb's industrialit system are the signs. The fourth generation of dcs has been formed. The most important symbol of the new generation of dcs is the two words beginning with I: informatization and integration.
From the functional point of view, the decentralized control system is a multi-functional hierarchical control system. Distributed control system can be divided into four levels: direct control, process management, production management and operation management.
Computers with different types and functions are used at all levels to form subsystems with certain relative independence and undertake designated tasks. High-speed data communication lines are used to connect with each other, transmit information to each other and coordinate work.
The direct control level, also known as the process control level, is the basis of dcs, which realizes the tasks of data acquisition, process control, equipment monitoring, system testing and diagnosis, alarm and redundant switching in the production process. The process management layer, also known as the supervisory management layer, comprehensively monitors all the information of each station in the process, and is responsible for the coordination and management of the work of each direct control layer and the contact with the computer of the superior production management layer, in addition to completing the optimization control calculation and the setting of the optimal setting value of each production process. At the production management level, the management computer is responsible for production coordination, command and control of the overall production situation. The management layer resides in the central computer and is responsible for the overall coordination and management of the whole factory, the management methods and strategies of the enterprise, and the optimization of the whole production system.
The meaning of decentralized control system is mainly reflected in decentralization, which has two aspects: first, it emphasizes that the geographical location of various controlled production equipment is decentralized, and the corresponding control equipment of the system is also geographically decentralized; Second, the functions of the control system are decentralized, that is, the data acquisition, process control, operation display and monitoring operations of the computer control system are decentralized according to functions, that is, the risk of the whole system is decentralized. Using the communication network, storage equipment and software system of the system, the whole system is centrally monitored and operated, and centralized operation and management are carried out. It is beneficial to fully understand and effectively manipulate the production process and system operation.
The distributed control system adopts color screen display (such as ordinary crt, touch display and wall-mounted large screen) and convenient operation tools (such as keyboard, mouse and touch screen), which fundamentally improves man-machine contact. The operation is convenient and the display is intuitive, which provides the monitoring of the operated equipment. Configuration software provided by dcs includes system configuration, process control configuration, screen configuration, report configuration, etc. , which greatly facilitates users to design new control systems and flexible expansion systems.
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