Research On VAV Terminal Indoor Temperature Control System

The control performance of the air conditioning system is related to the thermal comfort of indoor personnel and the level of building energy consumption.The VAV air conditioning system has become one of the focuses of the air conditioning system research in recent years due to its characteristics of comfort,energy saving and flexibility.The VAV terminal room temperature control system is studied in this paper because the regulating performance of the VAV-BOX directly affects the operating quality of the VAV air conditioning system.The VAV terminal room temperature control system changes the opening degree of the air valve through the electric regulating valve,and then changes the air supply volume to meet the demand of room thermal load and stabilize the indoor temperature at the set value.Due to the characteristics of the terminal system,such as multi-variable coupling,time-varying parameters,input and output are non-linear,the traditional PID control is difficult to achieve the desired control effect in practical engineering.Therefore,advanced intelligent control algorithm can be used to formulate or optimize the control strategy and improve the control performance.The main contents of this paper are as follows:(1)Briefly analyzed the VAV air conditioning system,focuse on the study of the basic principle,type and control method of VAV-BOX.The mechanism mathematical model of each main link of the VAV-BOX is established by using the mechanism method.(2)The traditional PID controller is selected as the controller of the VAV terminal room temperature control system,and the control parameters are obtained through the engineering tuning method.Build the simulation model,and the performance of the control system is analyzed through simulation experiments.(3)Introducing the fuzzy control theory into the tradition PID control system,a fuzzy self-tuning PID controller with both advantages is obtained.During the operation of the VAV terminal room temperature fuzzy PID control system,the proportional coefficient,integral coefficient and differential coefficient of the PID controller are self-tuned online.By comparing with the traditional PID control system,the superiority of the fuzzy PID control system is verified.(4)In view of the above two kinds of control modes in system modeling inaccuracies,time-varying and fuzzy control rules too dependent on characteristics of expert experiences,put forward a new strategy,introducing the neural network model predictive control theory into the VAV terminal room temperature control system.Identifing the terminal system,controller and the system model is established for simulation,verify the feasibility of this control strategy,provides a new idea for the VAV terminal room temperature control.