DCS is the abbreviation of Distributed Control System, commonly referred to as Distributed Control System in China. It is a multi-level computer system composed of process control level and process monitoring level, connected by a communication network. It integrates 4C technologies such as computer, communication, display, and control. Its basic idea is decentralized control, centralized operation, hierarchical management, flexible configuration, and convenient configuration. DCS has the following characteristics:
(1) High reliability
Due to the DCS’s decentralized implementation of system control functions on various computers, the system structure adopts fault-tolerant design, so the failure of one computer will not cause the loss of other system functions. In addition, due to the relatively single task undertaken by each computer in the system, specialized computers with specific structures and software can be used for the functions that need to be implemented, thereby improving the reliability of each computer in the system.
(2) Openness
DCS adopts an open, standardized, modular, and serialized design. Each computer in the system communicates through a local area network to achieve information transmission. When it is necessary to change or expand system functions, new computers can be easily connected to or removed from the system communication network, almost without affecting the work of other computers in the system.
(3) Flexibility
By using configuration software to configure software and hardware according to different process application objects, namely determining measurement and control signals and their interconnections, selecting applicable control laws from the control algorithm library, and calling basic graphics from the graphics library to form various monitoring and alarm screens required, the required control system can be conveniently formed.
(4) Easy to maintain
A small or micro specialized computer with a single function, characterized by simple and convenient maintenance. When a certain part or computer malfunctions, it can be replaced online without affecting the operation of the entire system, quickly eliminating faults.
(5) Coordination
Various data is transmitted between workstations through communication networks, and the entire system information is shared and coordinated to complete the overall functions and optimization processing of the control system.
(6) Complete control functions
The control algorithm is rich, integrating continuous control, sequential control, and batch control. It can achieve advanced control such as cascade, feedforward, decoupling, adaptive, and predictive control, and can easily add special control algorithms as needed.
The composition of DCS is very flexible, which can be composed of dedicated management computer stations, operator stations, engineer stations, recording stations, on-site control stations, and data acquisition stations, as well as general servers, industrial control computers, and programmable controllers.
The process control level at the bottom level is generally achieved by decentralized on-site control stations, data acquisition stations, and other on-site data collection and control, and transmitted to the production monitoring level computer through a data communication network. The production monitoring level conducts centralized operation and management of data from the process control level, such as various optimization calculations, statistical reports, fault diagnosis, display alarms, etc. With the development of computer technology, DCS can be connected to higher performance computer equipment through a network as needed to achieve more advanced centralized management functions, such as planning and scheduling, warehouse management, energy management, etc.