Design And Experiment Of PLC-based Automatic Control System For Integrated Drip Irrigation Of Farmland Water And Fertilizer

The traditional manual irrigation or semi-automatic irrigation method has problems such as high water consumption,high salinization rate,and a large amount of fertilizer water flowing into lakes after irrigation,causing serious eutrophication of water bodies,which can no longer meet the needs of modern agricultural development.Therefore,the degree of automation of farmland water and fertilizer integration irrigation technology restricts the process of rapid development of high quality and high yield of crops in the river-loop irrigation area.Based on the research and testing of water resources and soil conditions in the Loop,we completed the selection and structural layout of the first pivot component based on the Wuliang Suhai agricultural test field,determined the basic functions of the drip irrigation system,and provided the design requirements for the PLC-based automatic control system for drip irrigation in agricultural fields.The control system is designed with upper and lower units,and the lower unit uses a Siemens SMART200 PLC to communicate with sensors in the field via Modbus protocol to control the actions of the actuators.The manmachine interaction system in the upper station uses a Kunlun Tongzhou touch screen and is connected to the lower station through a network cable.The system is highly automated and can accurately measure soil moisture and nitrogen,phosphorus and potassium content,balance soil PH value,realize intelligent irrigation and fertilization,greatly reduce the waste of water and fertilizer,and improve agricultural production efficiency and yield of agricultural products.The main work content is:(1)According to the soil physical parameters of Wuliang Suhai area,the drip irrigation method is preferred for irrigation.According to the characteristics of water quality with many impurities,the filtration equipment adopts the combination of gravel centrifugal filter and mesh filter,and the selection and structure modeling of water and fertilizer integrated drip irrigation equipment.(2)Hardware design of integrated drip irrigation control system for water and fertilizer.Due to the large number of equipment components and high rated voltage,and considering the expansion of subsequent automation functions,PLC is used as the control center,sensor equipment is selected according to the irrigation requirements of the farmland in the demonstration park,I/O control points are assigned,and the installation and wiring of the control box are planned to ensure the functional achievability and operational stability of the automatic farmland irrigation system.(3)Software design of the integrated drip irrigation control system for water and fertilizer.Program design for irrigation and fertilization parameters of farmland.The automatic irrigation program,automatic fertilizer application program,water and fertilizer PH value fuzzy control program,sensor Modbus communication and human-machine interaction program design were completed,and the fuzzy simulation model was established with Simulink module and the reliability of the model was verified.In the design process,this project fully considered the special environmental and climatic conditions of the Wuliang Suhai region,and improved the system control accuracy and automation through the design and optimization of sensors,PLC and human-machine interaction system.Through experimental verification,the system is highly stable and can accurately measure the soil water content and fertilizer content of farmland to achieve precise fertilizer application and irrigation,which maximizes the utilization rate of water resources and target application efficiency of fertilizer,and has great application and promotion value.