State Space Modeling For Multi-zone VAV Air-conditioning System And Its Optimized Control Research

Variable air volume air-conditioning (VAC AC) system is a new-type air-conditioning technology which was developed as demanding of energyconservation. Due to its excellent thermal comfortability and ideal energy-saving, VAV AC system is put into widespread application. The nonlinear andtime-dependent features make the control of VAV AC more difficult than theconstant air volume system. Thus，developing a simulation model seemsessential to designing optimized control for VAV AC system.Based on the state space model theory, the dynamic models for eachcomponent of VAV AC were developed which featured in multi-input-multi-output. The model could reflect the components’ transient response to the inputdisturbance. Then the key parameters in the model were determined throughexperiment and the validation of the model was conducted. The simulationresults were in good agreement with the experiment data.A system model was developed by combining the validated componentmodels which were used for simulating the dynamic operation of a simplifiedVAV AC under different operation condition. Based on the established model,a GPC controller was designed to keep the supply air temperature at a requiredvalue by regulating the cooled water flow rate of the surface heat exchanger.The simulation results manifested that the supply air temperature could beeffectively maintained at a favorable level under the GPC strategy whichrealize the ideal control effect. Besides, the optimized fan speed tactics underdifferent system air volume is determined using the VAV AC system model tomeet the demand of reducing the energy consumption of fan.