| Micro-irrigation is internationally recognized as the most water-saving irrigation technology,and is an important direction of development of the current domestic and international water-saving irrigation.Comparing with drip irrigation, its water consumption is about 20~30%, which water saving is about 70%. Running intelligent micro-irrigation techniques, you can use greenhouse bucket, hills and mountains fall naturally self-pressure irrigation, with water and energy saving, anti-clogging ability,precision irrigation, efficient fertilizer, increase production, intelligent management,equipment utilization advantages, meeting efficient agricultural production in Hilly and mountainous areas need.This study designed a semi-permeable membrane micro-irrigation intelligent equipment, using PLC as the core controller,Water pump and solenoid valve for the implementation of components. In the system model, the crop water requirement of the crop water requirement is recommended by the United Nations Food and Agriculture Organization FAO crop water requirement expert advisory group, according to the meteorological factors of monitoring of temperature, net radiation to obtain crop evapotran spiration, and by different crop coefficient, we derived for different crop of daily water demand. Through a semi-permeable membrane moistube hydraulic performance test, we obtain the water head height of the moistube. According to the principle of pressure head control, we design the upper and lower limits of water level in the system, monitoring the value of liquid level sensor, we obtain the height of the water level of the water tank to the inlet of the mositube and call the height h, using the controller to control the execution of the element water pump and the electromagnetic valve, making height h between the lower level and the upper lever.The main research contents are as follows:1、we study on the semi-permeable membrane moistube and lay on the analysis of the relationship of pressure and flow in the moistube 10 cm buried under soil conditions. We choose the semi-permeable membrane moistube which is made in Shenzhen city, and the test site is in fluid sprinkling hall of Jiangsu UniversityResearch Center of technology,the temperature of the hall between 5℃ and 9℃,environment relative humidity from 50% to 60%. We change the test water head by the lifting platform, under the pressure head of 1.10 m, 1.5m, 1.90 m, 2.30 m, 2.50 m and so on in respectively, we measure the flow of moistube under the condition of buried soil10 cm, and use software to fit the test results.2、Establish the relationship between temperature, the amount of net radiation and the reference crop evapotran spiration to determine the daily crop water requirement.through the daily crop water requirement to determine irrigation decision-making.According to the current weather conditions,we determine the formula for calculating the reference crop evapotran spiration, According to the crop coefficient of different crops, we get the crops daily water demand. According to the semi-permeable membrane moistube buried soil income flow and head relation and determine the semi-permeable membrane moistube irrigation water head height h, determined by the regulation of irrigation pressure head, water level upper limit of irrigation system design : 1.1h, the water level lower limit : 0.9h. Finally, the water level is controlled in the range of 0.9h to 1.1h.3、Analysis of irrigation decision-making model to design the overall layout of the system and design the circuit diagram, and then design the hardware part of the hardware for reasonable selection. The hardware part mainly includes the monitoring devices, the implementation of components, control components, monitoring components mainly by the liquid level, temperature, net radiation sensor, actuator is mainly composed of a water pump, an electromagnetic valve, control element is a programmable logic controller, namely the PLC. According to the circuit diagram of the system, the hardware components are carried out and the hardware is debugged.4、According to the control principle, the software design scheme is determined.The software part includes controller programming software, Kingview software.Controller programming software using ladder diagram and C language module to achieve sensor signal acquisition and processing, the numerical calculation of the technical model, the actual value and the set value of the comparison and so on.according to the regulation scheme, irrigation pressure head is controlled in the designrange, in order to achieve the best effect of crop irrigation. Monitoring software is recorded on the field data of the whole system to record and monitor the important parameters such as liquid level,temperature, net radiation, lower and upper limit of irrigation pressure head, draw the real-time curve picture of irrigation pressure head,query the historical data and print the report.In the end, the control process of the system is shown in the form of pictures.5、Debugging system. We set the system in a specific operating environment, the system is in normal operation state and some unexpected state system test, such as water tank liquid level is too low or too high, whether the alarm will be in the emergency situation, pump and valve operating conditions to achieve the desired effect,and to determine the whole irrigation system is reliable. |
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