Variable Air Volume Air Conditioning System Modeling And Intelligent Control Study

With the development of technology and improvement of living standard, air conditioning systems have become an important part of daily life, and their energy consumption drew more and more attention. Variable air volume (VAV) system gradually became the trend of large air conditioning system become of its great potential of energy conservation. Control system in VAV system is usually consisted by multiple PID control loops. But because the air conditioning system is a system of strong coupling and nonlinear, PID controller can hardly achieve satisfied performance. So it is necessary to study new control technologies to improve the performance of VAV system.The modeling and control strategies of VAV system are studied based on analysis of its operation process in this thesis, the main achievements are as follows:Firstly, conditioned zone model and VAV air side system model are proposed which establish the fundamentals of the study and analysis of VAV system control strategies.Secondly, fuzzy control technology is introduced to zone air temperature controller design because of the deficiency of PID controller on this aspect; a fuzzy-PID is designed. Simulations are done to obtain its performance as well as its influences on other control loops. The results demonstrate that fuzzy-PID control unit not only improve the control precision when compared to the traditional PID control but also shows its advantages on system stability, energy conservation.Finally, on the basis of VAV air side system model, fuzzy controller is applied to coordinated control of air side system. The simulation results show that fuzzy coordinated control strategy can achieve better performance as well as saving energy compared to traditional coordinated control strategy.Fuzzy intelligent control method investigated in this thesis achieve good control performance when applied in zone air temperature control and coordinated control in VAV system, which is a benefiting explore in applying intelligent control to VAV system.