The Development And Research Of Plant Heating Ventilation Air Conditioning System Based On PLC Control

Now the construction industry has developed rapidly. When it improves the living environment, it has been increasing energy consumption at the same time. With the total energy consumption is rising year by year, the most energy consumption is from the air conditioning unit in the heating system. It is more than about ninety percent of the whole building energy consumption, and it is more than twenty percent of the total energy consumption in the whole society. Such a huge energy consumption, it is not only accelerates the energy crisis, but also leads to the waste of resources and environmental pollution. So it is very necessary to reduce the energy consumption of the construction industry, especially the energy consumption of the heating ventilation air conditioning. And it is very necessary to take appropriate controlling strategies to raise the level of the automatic control of air conditioning, realize the energy saving.Take the heating ventilation air conditioning unit in the plant as the researching object, analyses the possible factor that it causes the energy consumption of the air conditioning unit very largely. Thus it is concluded that the level of automation control system in air conditioning unit and the efficiency is low, the energy consumption is large. And put forward the subject that research and develop the air conditioning unit controlling system based on PLC technology. This paper introduces the controlling process of the heating ventilation air conditioning system in the factory in detail. It expounds the working principle of the air conditioner in each process and controlling method of the main equipment. According to the actual situation of the factory and the second law of thermodynamics, we established the mathematical model of temperature and humidity of the air conditioning system. Based on the mathematical model, we established the mathematical expression of the temperature and humidity, accomplish designing the PID controller of the air conditioning unit.By combining the PLC with the PLC and PID control technology, we completed the whole hardware system design of the control system of the air conditioning unit.Based on the equipment of AB company Control Logix series PLC, we design a set of practical, safe, reliable, economic, air conditioning automatic control system, by using mathematical model, PLC control technology and PID controlling method. Based on Windows XP system operation platform, we use the Factory view studio software to build an air conditioning automatic controlling project, including engineers station, monitoring system images, and alarm trend log.The air conditioning unit control system optimizes the control of the operation of air conditioning unit. It can dynamically detect and track the air conditioning load, so it realizes the real-time control of air conditioning unit operation. It effectively solves the problem that under the complex load changing the air conditioning unit adjustment ability is poor. So it improves the efficiency of air conditioning unit and the energy efficiency when the working condition is complex and achieves the best energy-saving effect.