The Research And Design Of The Central Air-condition Control System

With the rapid development of intelligent-building and automatic-control technology, central air-conditioning system becomes an indispensable part of a large building. Because of its complex structure, nonlinear and long time-delay lead to it a large energy consumption of buildings, how to realize the optimization of control-system and energy saving has become an important research focus today.This paper first describes and studies the background research and technology development status about the control system of central air-conditioning. In the background of Wanjiali-International-Mall central air-conditioning control system project, it introduces the working principle of the whole system and the selection of main equipment. The control strategy is described in detail. According to the characteristics of that the mathematical model is difficult to establish accurately, it presents the design and Simulation of a fuzzy-controller based on fuzzy control theory, and designs the program of PLC and a good PC monitoring system. The system also uses the frequency conversion technology, database,MODBUS-RTU and OPC-technology. they make the whole control-system and data processing more convenient and flexible. The efficiency and stability of system is improved greatly.Fuzzy-controller includes the variables selection and fuzzy of input and output, combined with the actual needs, knowledge and experience, it builds the fuzzy rules and reasoning process, finally, selecting a rational method of defuzzing, then a fuzzy output table following. It simulates controller in matlab, and compare with the PID, it shows an advantage in adjust-time and response speed. The HMI is based on the ArgusSoft configuration software which takes the database as the core. The system includes screen-display and data management. Such as the configuration data, monitoring interface, equipment-operating, modification of data, rights management, alarm-preservation and historic query etc. It provides a modular design, visual image, convenient operation for the operator at the same time makes the security of system and database.Finally, the system-debugging is described. It needs to test and analyse whether to meet the requirements. Aiming at the problems in process, the solutions are given. To ensure the design of system is in safe, reliable and stable, it can also save energy.