The Research Of The Central Air-conditioning Distributed Control System In The Intelligent Buildings

This research is based on the project of Kaitong building in Luogang District of Guangzhou, which investigated systematically the distributed control of frequency conversion system of the central air-conditioning. Additionally,the intelligent monitoring and control system combined with the computer and touch-screen technology was designed, in which the RS-485/232communication bus were used as the platform.In this work, the automatic control system of the central air-conditioning of the project is analyzed detailed firstly. Then, the PID frequency conversion control was designed and applied successfully for some equipments in the central air-conditioning room, such as compressor, cooling pump and refrigeration pump. And a PLC program for the whole distributed control system is designed on the basis. In addition, the PID control, which was used widely in the central air-conditioning control system, was introduced in detail. The result suggests that the PID frequency conversion control method in the central air-conditioning is very effective after testing repeatedly in the practical application because of it’s faster dynamic response velocity. Nowadays, the touch screen technology is applied everywhere, especially in the field of industrial control. Combined the powerful functions of PLC control system with the intuitive configuration software, the touch screen is easier to use, more reliable to operate and more direct to display the work state of the system. The combination of the technology and professional air-conditioning technology has been gradually applied to the central air-conditioning system with the progress of frequency conversion technology and the reduction of the cost. The most important feature of the control system we designed in this work is that it could not only ensures the stability of the control system, but also convenient the on-site operation for technician.