Design And Realization Of Central Air Conditioning Monitoring System Based On PROFIBUS In Intelligent Building

In modern times the central air-conditioning has become an essential part of large intelligent buildings,it provides people a comfortable living and working environment,but because of its complex structure and large system,it is difficult to deal with the fault detection and processing which brings a lot of work to the staff.So how to monitor the central air conditioning system equipment is an effective measure to solve this problem.First of all,combined with the domestic and foreign development situation of central air-conditioning system.We introduce the basic structure of the central air conditioning system and sub working principle,then the paper put forward the proposals for central air conditioning system based on PROFIBUS.according to the relevant theoretical knowledge of the field bus.Secondly,after analyzing the control demand of central air conditioning system,we use the Siemens WinCC as system monitoring platform to realize the central air conditioning subsystem's real-time monitoring and data's analysis and complete the design of operator station,the process station and gateway station of the central air conditioning system.Because of the traditional intelligent building's large network load and the delay of communication data transmission,it is difficult to guarantee the quality of remote monitoring,The traditional central air conditioning is through the RS485 bus to realize data transmission and because of its own transmission mode of the number of restrictions,communication distance and the speed of response.We design a new type of central air-conditioning control system which includes the new thermostat through the Modbus/TCP gateway for data transmission.In order to further improve the performance of the gateway stability,and it can effectively solve the above problems.In view of the central air conditioner motor variable frequency system is based on none speed sensor vector control system,and the vector control system has a high requirement to obtain accurately motor speed.This paper uses the voltage current flux of mixed observation model and it can identify the motor speed more accurately,and thus it can improve the none speed sensor vector control system of motor variable frequency system's performance and improve the stability of the central air conditioning running.Finally,we use PLC as the control core of field equipment control and through field bus technology for central air conditioning to realize each node on-line debugging,and then realize the design of dynamic images,system report,trend curve,energy consumption report and switching functions in both English and Chinese which based on WinCC.Combined with Bang-Bang control,PID control,and fuzzy control design of the mixing port control system to improve the control system of the robust performance and stability.