Design of Precision Mixing Fertilizer System for Potato Water and Fertilizer Integration Based on PLC
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摘要:
针对当前我国大田马铃薯水肥一体化灌溉系统混肥和检测不精确、没有具体针对马铃薯作物、智能化程度低等问题,设计研发了一款基于PLC、物联网控制的精确控制水肥一体化系统。由于大田马铃薯生长环境差、不稳定因素多,该系统使用PLC控制。相比较单片机的控制方式,PLC具有可靠性高、抗干扰能力强、编程简单方便、恶劣工作环境适应性强和施工方便等很多优点。由于传统大田水肥机利用增压泵将文丘里吸肥器吸取的肥料直接注入主管道利用水流冲刷自然混肥,无法保证混肥的精准性,EC、pH传感器也无法精准测量,导致田间作物肥料浓度无法保证一致,作物质量及产量相对较低。相比传统水肥机,增加混肥腔混肥能够明显降低水肥浓度误差。EC、pH传感器实时读取当前的水肥浓度及酸碱度,与预设值做PID运算,再将PID输出通过线性转换转换为脉冲输出时间,通过PLC输出控制文丘里电磁阀的通断吸肥时间,实现水肥浓度的精确调整,配合恒压变频柜使水压在设定值范围内波动,实现水肥精确、稳定输出。
Abstract:Aiming at problems of inaccurate fertilizer mixing and detection, no specific target for potato crops, and low level of intelligence of current field potato water fertilizer integrated irrigation system in China, a precision control water fertilizer integrated system based on PLC and Internet of Things control was designed and developed. Due to poor growth environment and many unstable factors of potato in the field, the system used PLC control. Compared with control mode of single chip microcomputer, PLC has many advantages such as high reliability, strong anti-interference ability, simple and convenient programming, strong adaptability to harsh industrial environment and convenient construction. Because traditional field water fertilizer machine used a booster pump to directly inject fertilizer absorbed by the Venturi fertilizer aspirator into main pipe to flush natural fertilizer with water, accuracy of fertilizer mixing cannot be guaranteed, and the EC and pH sensors cannot be accurately measured, resulting in inconsistent fertilizer concentrations of crops in the field, and relatively low crop quality and yield. Compared with traditional water fertilizer machine, adding fertilizer mixing chamber could significantly reduce concentration error of water and fertilizer. EC and pH sensors read current water and fertilizer concentration and pH in real time, perform PID calculation with preset value, and then converted the PID output into pulse output time through linear conversion. The on-off fertilizer suction time of Venturi solenoid valve was controlled through PLC output to achieve accurate adjustment of water and fertilizer concentration, and water pressure fluctuated within set value range with constant voltage frequency conversion cabinet to achieve accurate and stable output of water and fertilizer.
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Keywords:
- potato /
- water and fertilizer integration /
- PLC control /
- Internet of Things /
- fertilizer mixing chamber /
- PID
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表 1 I/O地址分配
Table 1. I/O address allocation
项目 元件 编号 输入 A通道流量计 X0 B通道流量计 X1 C通道流量计 X2 输出 A阀(肥液) Y0 B阀(肥液) Y1 C阀(酸液) Y2 施肥泵 Y3 主泵控制点 Y4 搅拌1 Y5 搅拌2 Y6 搅拌3 Y7 表 2 静态混合器参数
Table 2. Parameter of static mixer
项目 指标值 型号 SK-686100 公称直径/mm 100 D/mm 110 L1/mm 990 L2/mm 850 参考流量/(m3·h−1) 30~120 联结方式 法兰 压力等级 1 材质 UPVC 表 3 EC值田间试验数据
Table 3. EC field experiment data
单位:μs/cm 位置 60 s 120 s 180 s 240 s 300 s ① 2340 2400 2450 2500 2460 ② 2440 2440 2480 2490 2420 ③ 2310 2390 2480 2470 2520 设定值 2500 平均值 2363 2410 2453 2487 2467 差值 −147 −90 −47 −23 −33 表 4 pH值田间试验数据
Table 4. pH field experiment data
位置 60 s 120 s 180 s 240 s 300 s ① 6.59 6.59 6.40 6.47 6.53 ② 6.52 6.53 6.45 6.44 6.47 ③ 6.49 6.40 6.41 6.43 6.49 设定值 6.50 平均值 6.53 6.51 6.42 6.45 6.50 差值 0.03 0.01 −0.08 −0.05 0 -
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