Research And Design Of Heat-metering Measurement And Control System Based On Virtual Instrument

As the continued and rapid development of economy,the situation of energy shortage is becoming more clearly,energy-saving has become the focus of common attention of countries in the world.It play an important role in energy-saving of building carrying on a heating system reform and improving heating efficiency.At present,China's metering technology of heating is still in pilot stage.Metering method of heating don't have unified technical standards.At the same time,because users use autonomic regulation method,the traditional adjusting means of heating system is no longer suitable for the adjustment of metered heating system.In view of above existence question,two aspects are the focus of this thesis.One is comparing and analyzing each heating method,another is regulating the heating system effectively that heat metering has been reformed to satisfy the user requirements.Within the heating metering technology widely used,it changes traditional constant flow operation mode to variable flow operation mode which requires heating network can adjust automatically according the needs of users.Based on the analysis and study on adjustment and controlling theory of metering heating system,this thesis focus on implementation method's analysis of adjustment and control for heat metering in consumers heating system,it also has proposed a design scheme of metering heating measurement and control system.Combining with the Virtual Instrument technology and Fuzzy Control technology.it developed a metering heating measurement and control system based on Virtual Instrument technology.The system uses computer as hardware platform,graphical programming language LabVIEW as software development platform and PCI-6014 DAQ card of U.S. NI Company's for data acquisition and the controlling of signals output.The system not only meets heating variable flow system for operating regulation,but also improves the heating system efficiency of heating system operation greatly.Using the modern Virtual Instrument technology,modular hardware and software for rogramming,it obviousely reduced the development cycle and made the system has very strong scalability and transplantation,and made more easily for system renewal and upgrades.At the same time,it can display man-machine interface friendly,running state of thermal conditions intuitively and concisely using of Lab VIEW as a system development platform.Firstly,this thesis introduced the source of subject,current status of study and significance.Secondly,it did comparative analysis on each heat metering method that existed from working principle and system structure.It also has a deep study in heating-network regulation approach of heat meter method,flow temperature coefficient method and hot distribution table method which has been incorporated in Gansu local standard Technical specification for heat metering of central heating system.What's more, it introduced the basic concept of Visual Instrument and construction of using LabVIEW as measurement and control platform briefly.Finally,it designed a metering heating measurement and control system based on Visual Instrument technology,and given a detailed description and analysis of hardware component and software component modules.System hardware include sensors,selection and distribution of DAQ card.On this basis, the thesis has studied two aspects of the software system components and concrete design scheme of several function modules combining LabVIEW platform. The two aspects of the software system components is the main program of the software process and the functional structure.Each module mainly include landing module.parameter setting module,multi-channel data synchronous acquisition module.temperature conversion module,signal analysis and processing module,signal output controlling module,saving and printing module and so on,in order to achieve the design of metering heating measurement and control system.Using the data which was metered in heat metering reforming project in Yuzhong,Gansu province,this thesis analysed three metering methods that include heat meter method,flow temperature coefficient method and hot distribution table method about the district heat consumption and heating index data,it provided a scientific basis for the selection of heating meter method.And it also did an emphatically analysis on energy-saving effects of heating metering measurement and control system.Heating metering measurement and control system can save about 25% heating energies comparing with manual regulation and 2% heating energies comparing with climate compensator. On the condition of meetting the heat demands of the users,the system realized maximum energy saving.