Design And Application Of Reconfigurable Universal DDC For Building Automation

In recent years,the rapid development and practical application of internet of things,big data and artificial intelligence technology have provided new ideas,new directions and new opportunities for the development of intelligent buildings,and a new type of intelligent building "smart building" came into being at the historic moment.Building networking system platform is a kind of "smart building" architecture proposed on the premise of analyzing the drawbacks of traditional intelligent building architecture,and on the basis of in-depth study of existing new technologies and theories.The system platform is a networked,self-organizing and reconfigurable system architecture,which can eliminate the problems encountered in the operation of traditional intelligent building system architecture,such as the difficulty of crosssystem coordinated operation of electrical equipment,heavy workload of configuration and poor reconfigurability.The reconfigurable universal DDC(Direct Digital Control)is the product requirement of building networking system platform and the equipment cornerstone of building networking platform.Firstly,the structure of building networking system platform is introduced,including perception layer,network layer,platform service layer and application layer.The position of reconfigurable universal DDC in the system platform and its functional requirements in building air conditioning system,fresh air system,water supply and drainage system,air supply and exhaust system,lighting system are analyzed.The hardware and software schemes of reconfigurable universal DDC,especially the multi-task partitioning and scheduling based on FreeRTOS embedded real-time operating system,are developed.Secondly,the reconfigurable universial DDC hardware circuit is designed,and four reconfigurable universal DDC are proposed for BAS(Building Automation System).The reconstruction method of general DDC is studied.A universal DDC reconstruction scheme based on dynamic link list is proposed.A basic unit library for building BAS system reconstruction was established,including 15 basic units such as PID module,delay module,mathematical operation module and logical operation module.The reconfiguration communication protocol between PC reconfiguration software and DDC is established by analyzing the interconnection between reconfiguration units based on intermediate variables.Thirdly,the reconfiguration function of universal DDC is realized and applied.The specific implementation methods of universal DDC reconfiguration function are studied,including the mathematical model of functional modules,the definition of reconfiguration variables,and the reconfiguration algorithm unit.The upper computer reconfiguration software is developed,including reconstructing basic units,reconstructing software interface and reconstructing information download.The general DDC is applied in air conditioning system,fresh air system,air supply and exhaust system,water supply and drainage system and lighting system.Then,the function of LoRa-based DDC wireless ad hoc network is studied.Firstly,the structure of wireless sensor network is selected and the characteristics of wireless network are analyzed.Secondly,the channel allocation strategy based on pseudo-random sequence,multirouting selection strategy based on data fusion,multi-routing redundancy adaptive transmission strategy,boot-up automatic networking and network dynamic maintenance algorithm are specifically designed.Finally,the performance indicators of wireless sensor networks are tested.Finally,the reconfigurable universal DDC is applied in constant pressure water supply system and intelligent lighting control system,which further verifies the stability,reliability and realizability of the reconfigurable function of the developed products,thus laying a solid foundation for building networking system platform.