The Study Of Minimum Total Supply Air Volume Control In Variable Air Volume Air-conditioning System

Of all Ihe Building Automation Systems (BAS), heating, ventilating and air-conditioning (HVAC) systems are most important from the viewpoint of saving energy and improving the quality of the indoor environment. Therefore, adopting efficient control strategies for air-conditioning plays a vital role in developing improved energy management control (EMC) systems for intelligent buildings (IB). Nowadays, VAV air-conditioning system has gradually become most popular in China and abroad because of its sigraficant energy saving. The paper studies the static pressure control and minimum total supply air volume control of VAV air-conditioning system by experiment At present VAV air-conditioning system are all modelled by the method of mechanism analysis. To the point the paper ideritifies the part of the air-handling unit by the recursive least-squares method. It is concluded that the models of water damper-supply air temperature's loop and supply air fan-static pressure's loop ate close to the teal system. Genetic algorithm is used to optimize the parameters of PID controller that is used to control the plant LON (local operating network) is designed to control VAV air-conditioning system. By this means the static pressure control and minimum total supply air volume control are experimented. The paper analyzes the coupling among loops, the whole system's stability and energy saving effect under the two control methods. The experiment's results show that the system is stable under the static pressure control and energy saving under the minimum total supply air volume control. Although the terminal dampers's tuning time is prolonged under the minimum total supply air volume control, it can be reduced by adopting the appropriate sampling time when debugging the system. From all of this we can conclude thart the minimum total supply air volume control has a good application perspective. Also, the paper has provided a program for the system's monitoring and control. It is designed by visual basic. The program has fine operating interface and exchanges data with the system of Lonworks and Metasy by DDE (dynamic data exchange) technique.