Data Communication And Real-time Optimization Research On Air-condition System In Intelligent Building

With continuous progress of our country’s urbanization advancement and theimprovement of people’s living conditions, people’s request to indoor environmentare also getting higher and higher. Heating、 ventilation and air conditioning(HAVC)are important guarantee of human healthy, comfortable working and livingenvironment. The proportion of the operating energy consumption of HVAC systemagainst building energy consumption is becoming larger and larger. It is the key ofreducing the energy consumption of HVAC system that making HVAC system in theoptimal operating status on the condition that people’s demand of the indoorenvironment conditions is met. Therefore, it is particularly important that faultdiagnosis and optimal control for HVAC system are done.In onder to acquire the real-time operating data for fault diagnosis and optimalcontrol of HVAC system, this paper first analyzes Data Access Specification of OPCtechnology. On the basis of the above， the OPC Client is developed by OPCtechnology on the platform of visual basic6.0and can communicate with OPC Serversuccessfully. The data acquiring and sending for the field equipment is realized. TheOPC Client developed by OPC technology can run continually and stably. Then, thispaper introduces in detail BACnet, the sole data communications in HVAC system.Data communication program is developed on the basis of BACnet protocol, and acomparison with the current popular data communication protocols in HAVC systemis made. With the advantages of BACnet protocol, the data communication programdeveloped by BACnet protocol realizes operating data acquisit form the fieldequipment. Lastly, this paper introduces optimization of chilled water supplytemperature setpoint in the air-condition system. According to the dynamicmathematical model of chiller established by the real-time operating data, a method tooptimize chilled water supply temperature set point in the air-condition system isproposed in this paper.The real-time field data can be collected by the OPC Clientprogram. Based on the relationship between the chiller power consumption and thepart load ratio, and the real-time dynamic model established by the least squaremethod of forgetting factor, the optimal PLR(Part Load Rate) of each chiller by usingSQP methods (sequential quadratic programming) can be easily worked out. Then theoptimal chilled water supply temperature setpoint of each chiller can be obtained.According to the method above， the real-time optimization program has been developed.In this study, the research object is the chilled water system in a largecommercial building located in Hong Kong. The data communication program andoptimal control program has been validated online and can run continually and stably.