Control Of The Central Air Conditioning Refrigeration System Based On DCS

With the development of people’s living standards, the air conditioning system has become a part of people’s lives, it improves the comfort of people’s lives, and the energy consumption of the air conditioning system has also become an urgent problem in today’s energy shortage environment. With the substantial rise of building automation, energy saving and intelligent control of a central air conditioning system has become the focus of research in this field.First of all, on the basis of reading many foreign and domestic references, it summarizes the development and status of the Central Air Conditioning Refrigeration System as well as the knowledge of distributed control system. In the thesis, the DCS-based control of central air conditioning refrigeration systems has been put forward.Followed by, in the design of central air-conditioning and refrigeration control system based on DCS, The thesis took the ABB AC700DCS as the control platform and carried out the automation control of the central air-conditioning and refrigeration systems. Aspects of cooling water、refrigerator and chilled water for the refrigeration system realized real-time monitoring and feedback of the important variables. The cooling towers、 cooling pumps、refrigeration pumps and compressors realized the control of start and stop and frequency. This paper used self-tuning PID to control superheat degree at the outlet of the evaporator up to the ideal setting by opening of electronic expansion valve. It achieves a reasonable distribution of refrigerant and improves the energy efficiency of air conditioning. Finally, the project had experimental implementation by the central air-conditioning system HVAC experiment platform and realized successful online. Operator station can display the condition of the central air-conditioning water system in real time conditions and have the remote control of various parts, the control operation is simple. The project had simple control, accurate, rapid, high reliability, high degree of automation characteristics.The DCS control central air-conditioning system, it play DCS system the advantage of real-time、fast and accurate. The project achieved good control effect and improve the control quality, it realized automated control of the central air-conditioning system and provided stability and reliability of the system.