Design And Application Of Intelligent Greenhouse Based On PLC

With the development of agricultural refinement and industrialization,the demand for agricultural facilities is becoming more and more important.As an important means of crop cultivation,the research and application of agricultural greenhouses is also more urgent.In the reality of using Chinese greenhouse,the foreign equipment is introducted mostly and directly.Due to the greenhouse at the beginning of the design,it is based on the actual conditions in foreign countries.Therefore,the control system from the control model to the executive body,doesn't match with Chinese agricultural production well.The control effect is not ideal with the high price.In addition,the most of the self-built traditional greenhouses in China are still limited to the simple insulation level.And the level of automation and modernization is very low,which is difficult to meet the requirement of the mass production of modern agriculture.The intelligent greenhouse with low cost and actual condition needs to be designed and developed.In combination with the actual project background,a complete set of intelligent greenhouse control system based on PLC is designed in this paper.First,the heat transferring balance of the greenhouse is analyzed.The temperature control model of the greenhouse is established,and the PID correction control based on the improved genetic algorithm is proposed.The control system is simulated with MATLAB,and the output status of the system is compared with the conventional PID and the improved algorithm PID setting.Also,the optimization effect of the correction control is verified.Then,the growth factors of the greenhouse crops are analyzed,and the control strategy and the control mode of the greenhouse control system is determined.According to the actual production requirements and gardening characteristics of greenhouse,the overall structure and hardware design of greenhouse control system is completed,including the control host and the mechanism of detection and execution about design,calculation and selection.In the light of the principle of hardware and electrical equipment,STEP7 Micro WIN and WinCC V7 are adopted to solve the development and the design of PLC programming and the host computer control interface,so as to realize the overall preliminary design of greenhouse control system.Thirdly,in FLUENT,numerical simulation and analysis of the wind speed,the temperature and the air flow in the inner space of the greenhouse are carried out.Some problems in the preliminary design are pointed out,and the improvement plan for the layout and the design of the greenhouse is put forward.Finally,the whole design scheme is implemented and installed,and the electrical device and system are debugged to verify whether to meet the control requirements.In view of some data in the actual operation process,the systematic error of greenhouse control system is analyzed theoretically based on the measurement technology.Then suggestions for correction are put forward.