Research And Realization Of Water System Control Strategy In Central Air-conditioning System

The function of central air-conditioning water system is heating or cooling rooms, and the energy consumption of this system has taken a great place in total energy consumption of building.Generally speaking,there are three ways to save energy of water system:one is strengthen the people's awareness of energy saving and teach the how to use central air-conditioning system rightly;The other one is improve and optimize the control strategy of central air-conditioning water system.The last one is centralization of management by computer.This paper discusses the latter two.After known and analyzed the traditional air-conditioning water system and variable water volume(VWV) system,definite every segment and eruptions'control strategy of VWV system,where the Laboratory is in Xi'an University of Technology and Architecture Intelligence Building Institute.Including number required of water chilling unit and primary pump,temperature control of chilling water,etc.Put emphasis on the control method of secondary variable water volume system.By analyzing the disadvantages of existing control method,in order to conquer that disadvantages, improve the system performance,the paper puts forward a new way named cascade control to deal with the frequency of secondary pump,then,design it.Nowadays,computer control technology has been wildly used.So the control strategy of VWV system should be realized after definite and improve the control strategy.First,a hierarchical network is set up.This network has three layers:element layer,where the sensors and executing agencies are;control layer,where the controller like Programmable Logic Controller are;management layer,where the industrial computers and configuration software are.The data interchange between these layers. The control algorithm programmed and run in the controller and host computers.The paper use"LabVIEW"to develop integrated software in order to manage the whole VWV system.At the same time,the transfer functions in the cascade control are identified,then,design a PID controller and adjustment variable of this regulator.At last, simulate and have an experiment on the real system by using LabVIEW.