Premixing type fertilization system and fertilization control method

Abstract

The invention discloses a premixed fertilization system and a fertilization control method, and belongs to the technical field of agricultural water and fertilizer integration, the premixed fertilization system comprises a water and fertilizer preparation system, a field fertilization system and a water and fertilizer application control system; the water and fertilizer preparation system comprises a water adding mechanism, a conveying mechanism and a fertilizer absorbing mechanism; the field fertilization system comprises a plurality of field plot fertilization pipes communicated with the main pipeline; the premixing type fertilization control method comprises the following steps: preparing a water and fertilizer solution according to a set value in advance by adopting a premixing type method, combining flow duty ratio characteristics of a fertilizer suction electromagnetic valve, obtaining a mother liquor EC value of each fertilizer liquid barrel through system operation, obtaining a relationship among parameters in real time, calculating a duty ratio of the fertilizer suction valve according to a real-time target value and each flow, and controlling the fertilizer suction electromagnetic valve according to the duty ratio. According to the method, the problems that the time for reaching the EC target value is long, the steady-state fluctuation is large, and the characteristics and parameters of control equipment cannot be automatically tested and corrected when the parameters change in the water and fertilizer integration technology are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural water-fertilizer integration, and in particular to a premixed fertilization system and a fertilization control method. Background Art

[0002] Integrated water and fertilizer technology is a technology that organically combines irrigation and fertilization, accurately couples water and fertilizer and supplies them to crops. It has many advantages such as water saving, high irrigation uniformity, labor saving, fertilizer saving, and increased yield. Compared with traditional irrigation modes such as flooding, integrated water and fertilizer technology can significantly improve the utilization rate of water, fertilizer and pesticides, usually saving 30% to 60% of water and 20% to 40% of fertilizer. Therefore, it has developed rapidly in my country and has been widely used.

[0003] Currently, the most commonly used integrated water and fertilizer equipment is a pipeline fertilizer applicator. A control system regulates water and fertilizer, continuously and quantitatively injecting a mixture of fertilizer and water into the irrigation pipe. The water and fertilizer mix in the main pipe, achieving integrated water and fertilizer. Its advantages include high-flow, continuous water and fertilizer supply at a low cost. However, it takes a long time for the water and fertilizer to reach the set EC target, generally taking 1-3 minutes, making it suitable for field crops with longer water and fertilizer cycles. In greenhouse substrate cultivation, water and fertilizer are applied simultaneously, 5-10 times per day, with 100-600ml of water per plant each time, for no more than 10 minutes. This requires achieving water and fertilizer concentrations quickly and accurately, even without the need for adjustment time. Instead, the water and fertilizer are adjusted to the required EC value before irrigation.

[0004] Existing premix fertilizer spreaders use a PID controller to control the duty cycle of the fertilizer suction solenoid valve based on the set EC target value, thereby varying the amount of fertilizer sucked in and gradually reaching the set EC value. However, the PID control method takes a long time to adjust, affecting the accuracy of water and fertilizer application. To address this issue, methods such as incremental PID algorithms, fuzzy controllers, and neural network models are currently being used to maximize the device's response speed. However, during the crop cultivation process, pressure, flow rate, mother liquor concentration, EC target value, and fertilizer type are constantly changing. Furthermore, factors such as pipeline transmission introduce severe nonlinearity, large lags, large inertia, and mathematical model uncertainty. These methods are only suitable for scenarios where some parameters are relatively fixed and cannot respond quickly to changing parameters. Therefore, the design of a premix fertilization system and fertilization control method is essential. Summary of the Invention

[0005] The object of the present invention is to provide a premixed fertilization system and a fertilization control method to solve the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a premixed fertilization system, comprising a water-fertilizer preparation system, a field fertilization system, and a water-fertilizer application control system;

[0007] The water-fertilizer preparation system includes a water adding mechanism, a conveying mechanism and a fertilizer absorbing mechanism. The water adding mechanism includes a water storage bucket, a water adding pump and a premixing bucket. The water suction end of the water adding pump is connected to the water storage bucket through a water delivery pipe, and the water discharge end of the water adding pump is connected to the premixing bucket through a water delivery pipe.

[0008] The delivery mechanism includes an irrigation pump, the water suction end of the irrigation pump is connected to the premixing barrel, the water discharge end of the irrigation pump is connected to the main pipeline, the main pipeline is connected to a fertilizer pipeline, one end of the fertilizer pipeline is connected to the premixing barrel, and the fertilizer suction mechanism is provided on the fertilizer pipeline;

[0009] The fertilizer suction mechanism includes a plurality of fertilizer suction pipes provided in the middle section of the fertilizer pipe, the middle section of the fertilizer suction pipe is connected to the fertilizer Venturi pipe, and one side of the fertilizer suction pipe is provided with a fertilizer mother liquid suction mechanism connected one-to-one with the fertilizer Venturi pipe;

[0010] The field fertilization system includes a plurality of field fertilization pipes connected to the main pipeline, and the field fertilization pipes are provided with field solenoid valves;

[0011] The water and fertilizer application control system is used to measure the initial water volume and the initial EC value of the water and fertilizer in the premix barrel, and pre-configure the EC value of the water and fertilizer in the premix barrel through the water adding mechanism, the conveying mechanism and the fertilizer mother liquid suction mechanism, so as to ensure that the EC value of the water and fertilizer entering the field is within the set value range at all times.

[0012] In a further embodiment, the fertilizer mother liquid suction mechanism includes a mother liquid barrel provided on one side of the fertilizer suction pipe, a stirring motor is provided on the top of the mother liquid barrel, and an output end of the stirring motor extends into the mother liquid barrel and is connected to the stirring mechanism;

[0013] The mother liquid barrel is communicated with an adjacent fertilizer venturi tube through a liquid suction pipe, and a fertilizer suction flow meter and a fertilizer suction electromagnetic valve are provided on the liquid suction pipe.

[0014] In a further embodiment, the water and fertilizer application control system includes a controller arranged outside the premixing barrel, an EC sensor and a fertilizer pressure sensor arranged on the fertilizer pipe in front of the fertilizer suction pipe, and the EC sensor and fertilizer pressure sensor are both electrically connected to the controller.

[0015] In a further embodiment, a water tank low water level sensor is provided in the water tank, a water flow meter is installed on the water pipe at the water outlet of the water pump, and a premixing tank water level meter is provided in the premixing tank.

[0016] In a further embodiment, a main flow meter is provided on the main pipeline.

[0017] In a further embodiment, a working pressure sensor is provided on the main pipeline in front of the field plot fertilizer pipe.

[0018] In a further embodiment, the controller includes a water adding pump frequency converter and an irrigation pump frequency converter, wherein the water adding pump frequency converter and the irrigation pump frequency converter are electrically connected to the water adding pump and the irrigation pump, respectively;

[0019] The controller is also electrically connected to the water adding pump, the irrigation pump, the fertilizing venturi tube, the fertilizer suction flow meter, the fertilizer suction solenoid valve, the water adding flow meter, the main pipe flow meter and the working pressure sensor.

[0020] A premixed fertilization control method comprises the following steps:

[0021] S1. Start the irrigation pump. After the pressure stabilizes for 10 seconds, open a fertilizer suction solenoid valve to suck a certain amount of mother liquid from the mother liquid barrel and then close it. After the EC value of the fertilization pipeline stabilizes for 5 seconds, record the EC sensor value ECa at this time. This value is the initial EC value of the water and fertilizer in the premix barrel.

[0022] Turn on the water pump to add water to the premix barrel. After calculating the amount of water added Qb using the water flow meter, wait until the EC value of the fertilizer pipeline stabilizes and record the EC sensor value ECb. The formula is:

[0023] *ECb=Qa*ECa, the initial water volume Qa in the premix barrel can be obtained:

[0024] Qa=Qb*ECb / (ECa-ECb)

[0025] Where: Qa is the initial water volume in the premix barrel, Qb is the amount of water added to the premix barrel, ECa is the initial EC value of the water and fertilizer in the premix barrel, ECb is the EC value of the water and fertilizer in the premix barrel after adding water, and the initial EC value of the water and fertilizer in the premix barrel and the initial water volume Qa are measured;

[0026] S2. Open the fertilizer suction solenoid valve in one of the mother liquid barrels and inject fertilizer liquid Q1 into the premix barrel. Q1 can be measured by the water flow meter. After the EC value of the fertilization pipeline stabilizes, record the EC sensor value ECc at this time. The formula is:

[0027] Qa*ECa+Q1*EC1=*ECc, the EC value EC1 in the mother liquid barrel can be obtained:

[0028] EC1 = *ECc-Qa*ECa) / Q1;

[0029] Repeat the above process for multiple mother liquid barrels to measure the EC values ​​EC1, EC2, EC3... in each mother liquid barrel respectively.

[0030] Repeat this step each time the mother solution is replaced to obtain a new mother solution EC value;

[0031] S3. Set working pressure and EC target value EC T , irrigation time, irrigation duration, proportion of each mother liquor, and field valves that need to be opened; when the irrigation time is reached, first check whether the premix barrel is at a low water level. If it is a low water level, start the water pump to add water. When the water level reaches 40cm or is not a low water level, start the irrigation pump, adjust the main pipe pressure to the set working pressure, and detect the EC value in the premix barrel. If it is greater than the set value, continue to add water. If it is less than the set value, adjust each fertilizer suction solenoid valve to suck fertilizer according to the set ratio, so that the EC value in the premix barrel reaches the set value. The EC value of water and fertilizer in the premix barrel is pre-prepared;

[0032] S4. When the EC value in the premix tank reaches the set value, the field plot solenoid valve is opened and the time is set. The irrigation pump is adjusted by the controller so that the working pressure sensor value reaches the set value. During the irrigation process, the controller ensures that the water pump flow rate is consistent with the irrigation pump flow rate.

[0033] During fertilization, the real-time main flow Q is obtained through the main flow meter, fertilizer suction flow meter and water addition flow meter. M , Fertilization flow Q F and water addition flow Q S , the water flow rate will be consistent with the main pipeline flow rate, so the water flow rate is used as the calculation basis, according to the target EC value EC set by the user T With the known mother liquor EC value and the set ratio, the duty cycle of the fertilizer suction solenoid valve can be calculated according to the following formula:

[0034] Qxi=(ki / )EC T *Q S / EC z

[0035] di=f(Qxi)

[0036] Where Qxi is the fertilizer suction flow rate of the i-th fertilizer suction pipe, k1...kn is the fertilizer suction ratio between n fertilizer suction pipes, EC T is the target EC value, Q S is the water addition flow rate, EC z is the combined EC value of each mother liquor, di is the duty cycle of the i-th fertilizer absorption solenoid valve at the target EC value, and f is the functional relationship between the flow rate of the fertilizer absorption solenoid valve and the duty cycle;

[0037] During operation, the duty cycle of each fertilizer suction solenoid valve is directly assigned in real time, so that the EC value of the water and fertilizer application control system can be quickly adjusted to the target EC value after operation. When the EC value is within the range of ±3% of the target value, PID regulation is enabled to achieve rapid stabilization, and the EC value of the water and fertilizer entering the field is within the set value range at all times;

[0038] S5. During operation, the water pump stops when the water level in the premix tank is high, the irrigation pump stops when the water level is low, the water pump stops when the water storage tank is low, and the fertilizer solenoid valve stops when the water level in the mother liquid tank is low, and an alarm is sounded; when the irrigation time is reached, the fertilizer solenoid valve, water pump, and irrigation pump stop, and the field plot solenoid valve is closed after 5 seconds, and the system ends operation.

[0039] In a further embodiment, a pressure reducing valve is provided at the inlet of the fertilization pipeline, and a pressure holding valve is provided on the main pipeline at the rear of the pressure reducing valve.

[0040] In a further embodiment, a main pipe pressure sensor is provided on the main pipeline in front of the pressure-sustained valve.

[0041] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention adopts a premixing method to prepare the water and fertilizer solution in advance according to the set value, which can achieve the EC value of the water and fertilizer entering the field within the set value range at all times; combined with the flow duty cycle characteristics of the fertilizer suction solenoid valve, the EC value of the mother liquor in each fertilizer liquid barrel can be obtained through system operation, and the relationship between various parameters can be obtained in real time, which can greatly simplify the control program and algorithm and reduce errors; the duty cycle of the fertilizer suction valve is calculated according to the real-time target value and each flow rate, which can achieve the EC value of the water and fertilizer entering the field within the set value range at all times; at the same time, combined with PID control, the adjustment is more accurate. The above method solves the problems in the water-fertilizer integrated technology of a long time to reach the EC target value, large steady-state fluctuations, and the inability to automatically test and correct the control equipment characteristics and parameters when the parameters change. The method is particularly suitable for small-area hydroponics in greenhouses or substrate cultivation where high requirements for water-fertilizer ratios are required. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a diagram of a fertilization system of the present invention;

[0043] Figure 2 is a characteristic diagram of the duty cycle of the solenoid valve of the present invention;

[0044] Figure 3 This is a flow chart for measuring the initial EC value and water volume of the premixing tank of the present invention;

[0045] Figure 4 This is a flow chart of measuring the EC value of the mother liquid barrel of the present invention;

[0046] Figure 5 This is a flow chart of the water-fertilizer integrated operation control of the present invention;

[0047] Figure 6 This is a graph showing the EC target value adjustment change of the present invention;

[0048] The accompanying drawings are marked as follows: 1. Low water level sensor of water storage tank; 2. Water storage tank; 3. Water adding pump; 4. Water adding flow meter; 5. Controller; 6. Water level gauge of premixing tank; 7. Premixing tank; 8. Mother liquor tank; 9. Stirring motor; 10. Fertilizer suction flow meter; 11. Fertilizer suction solenoid valve; 12. Fertilization Venturi tube; 13. Field area solenoid valve; 14. Working pressure sensor; 15. Main pipe flow meter; 16. EC sensor; 17. Pressure holding valve; 18. Pressure reducing valve; 19. Fertilization pressure sensor; 20. Main pipe pressure sensor; 21. Irrigation pump. DETAILED DESCRIPTION

[0049] In the following description, numerous specific details are provided to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without one or more of these details. In other instances, certain technical features well known in the art are not described to avoid confusion with the present invention.

[0050] See also Figures 1-6 , the present invention provides a technical solution: a premixed fertilization system, including a water and fertilizer preparation system, a field fertilization system and a water and fertilizer application control system;

[0051] The water-fertilizer preparation system includes a water adding mechanism, a conveying mechanism and a fertilizer absorbing mechanism. The water adding mechanism includes a water storage barrel 2, a water adding pump 3 and a premixing barrel 7. The water suction end of the water adding pump 3 is connected to the water storage barrel 2 through a water delivery pipe. The water adding pump 3 is controlled and operated by the water adding pump frequency converter in the controller 5. The speed of the water adding pump 3 is adjusted by the water adding pump frequency converter to achieve different flow rates. The water outlet end of the water adding pump 3 is connected to the premixing barrel 7 through a water delivery pipe. The water in the water storage barrel 2 is pumped to the premixing barrel 7. A water adding flow meter 4 is installed on the water delivery pipe at the water outlet end of the water adding pump 3. The controller 5 transmits a signal to the water adding flow meter 4, and the real-time water outlet flow rate can be detected; the premixing barrel 7 is used to mix water and fertilizer. It is connected to the water adding pump 3, the irrigation pump 21 and the fertilization pipeline through a pipeline. A premixing barrel water level gauge 6 is installed therein, and the controller 5 transmits a signal to the premixing barrel water level gauge 6 to detect the water level in the barrel.

[0052] The delivery mechanism includes an irrigation pump 21. The water suction end of the irrigation pump 21 is connected to the premixing barrel 7. The water discharge end of the irrigation pump 21 is connected to the main pipeline. The main pipeline is connected to a fertilizer pipeline. The irrigation pump 21 delivers water at a certain flow rate and pressure through the main pipeline to the field and the fertilizer pipeline. One end of the fertilizer pipeline is connected to the premixing barrel 7. The fertilizer suction mechanism is provided on the fertilizer pipeline.

[0053] The main pipeline is provided with a main flow meter 15 to measure the amount of water flowing from the main pipeline to the field in real time;

[0054] The fertilizer suction mechanism includes a plurality of fertilizer suction pipes provided in the middle section of the fertilizer pipe. The middle section of the fertilizer suction pipe is connected to the fertilizer Venturi pipe 12. A fertilizer mother liquid suction mechanism is provided on one side of the fertilizer suction pipe and is connected to the fertilizer Venturi pipe 12 in a one-to-one correspondence. When water flows through the fertilizer Venturi pipe 12, the fertilizer suction port of the fertilizer Venturi pipe 12 generates negative pressure, and the fertilizer mother liquid in the mother liquid barrel 8 is sucked in.

[0055] The field fertilization system includes several field fertilization pipes connected to the main pipeline. The field fertilization pipes are provided with field solenoid valves 13. The field solenoid valves 13 are located in each irrigation area of ​​the field to distribute water and fertilizer to the required planting area.

[0056] The water and fertilizer application control system is used to measure the initial water volume and the initial EC value of water and fertilizer in the premix barrel 7, and pre-configure the EC value of water and fertilizer in the premix barrel 7 through the water adding mechanism, the conveying mechanism and the fertilizer mother liquid suction mechanism, so as to ensure that the EC value of water and fertilizer entering the field is within the set value range at all times.

[0057] In a further embodiment, the fertilizer mother liquid suction mechanism includes a mother liquid barrel 8 provided on one side of the fertilizer suction pipe, a stirring motor 9 is provided on the top of the mother liquid barrel 8, an output end of the stirring motor 9 extends into the mother liquid barrel 8 and is connected to the stirring mechanism, wherein the stirring mechanism is a stirring blade, and the stirring motor 9 is electrically connected to the controller 5;

[0058] The mother liquid barrel 8 is communicated with the adjacent fertilizer venturi tube 12 through a liquid suction pipe, and a fertilizer suction flow meter 10 and a fertilizer suction electromagnetic valve 11 are provided on the liquid suction pipe.

[0059] Through the above technical solution, the stirring mechanism is driven to rotate by the stirring motor 9 to stir the fertilizer mother liquid in the mother liquid barrel 8 to make its concentration uniform. The real-time fertilizer suction flow rate is measured by the fertilizer suction flowmeter 10, and the opening time of the fertilizer suction solenoid valve 11 is controlled by PWM to control the fertilizer suction flow rate. The premixing barrel 7 is also provided with a stirring motor 8 and a stirring mechanism. Before the system is started, the stirring motors 8 of the mother liquid barrel 8 and the premixing barrel 7 are started for one minute. Thereafter, the stirring motor 8 keeps running during the operation until the water-fertilizer system stops working at the end of its operation.

[0060] In a further embodiment, the water and fertilizer application control system includes a controller 5 located outside the premixing barrel 7, an EC sensor 16 and a fertilizer pressure sensor 19 located on the fertilizer pipeline in front of the fertilizer suction pipe, and the EC sensor 16 and the fertilizer pressure sensor 19 are both electrically connected to the controller 5.

[0061] Through the above technical solution, the pressure of the fertilizer pipeline after the pressure reducing valve 18 is measured by the fertilizer pressure sensor 19 to determine whether the conditions for opening the fertilizer suction solenoid valve 11 are met to ensure the normal operation of all components of the system. The fertilizer suction solenoid valve 11 can be opened only when this pressure is greater than 0.05MPa. The EC value of the water and fertilizer after the water and fertilizer are fully mixed is measured by the EC sensor 16, that is, the final EC value entering the field. The controller 5 uses this value as the basis for controlling the amount of water and fertilizer applied.

[0062] In a further embodiment, a water tank low water level sensor 1 is provided in the water tank 2 .

[0063] Through the above technical solution, the water level in the water tank 2 is detected by the water tank low water level sensor 1, which is convenient for timely replenishment of water when the water in the water tank 2 is insufficient, wherein the water tank low water level sensor 1 is electrically connected to the controller 5.

[0064] In a further embodiment, a working pressure sensor 14 is provided on the main pipeline in front of the fertilizer pipe in the field plot.

[0065] Through the above technical solution, the main pipeline pressure after the pressure holding valve 17 is measured by the working pressure sensor 14, and this pressure is used to control the actual working pressure of each irrigation area in the field.

[0066] In a further embodiment, the controller 5 includes a water pump inverter and an irrigation pump inverter, which are electrically connected to the water pump 3 and the irrigation pump 21 respectively, wherein the controller 5 is also provided with a PLC, a display screen, related components and connecting lines, etc., and controls the operation of each component of the system according to the compiled program;

[0067] The controller 5 is also electrically connected to the water adding pump 3 , the irrigation pump 21 , the fertilizing venturi tube 12 , the fertilizer suction flow meter 10 , the fertilizer suction solenoid valve 11 , the water adding flow meter 4 , the main pipe flow meter 15 and the working pressure sensor 14 .

[0068] A premixed fertilization control method comprises the following steps:

[0069] S1. Start the irrigation pump 21. After the pressure stabilizes for 10 seconds, open a fertilizer suction solenoid valve 11 to suck a certain amount of mother liquid from the mother liquid barrel 8 and then close it. After the EC value of the fertilization pipeline stabilizes for 5 seconds, record the value ECa of the EC sensor 16 at this time. This value is the initial EC value of the water and fertilizer in the premix barrel 7;

[0070] Turn on the water pump 3 to add water to the premixing barrel 7. After the water flow meter 4 calculates the amount of water added Qb, wait until the EC value of the fertilizer pipeline stabilizes, and then record the value ECb of the EC sensor 16. The formula is:

[0071] Qa+Qb*ECb=Qa*ECa, the initial water volume Qa in the premixing tank 7 can be obtained:

[0072] Qa=Qb*ECb / (ECa-ECb)

[0073] Where: Qa is the initial water volume in the premixing tank 7, Qb is the amount of water added to the premixing tank 7, ECa is the initial EC value of the water and fertilizer in the premixing tank 7, ECb is the EC value of the water and fertilizer in the premixing tank 7 after adding water, and the initial EC value of the water and fertilizer in the premixing tank 7 and the initial water volume Qa are measured;

[0074] S2. Open one of the mother liquid barrels 8 in the fertilizer solenoid valve 11, into the premix barrel 7 to inject fertilizer liquid amount Q1, Q1 can be measured by the water flow meter 4, etc. After the EC value of the fertilization pipeline stabilizes, record the EC sensor 16 value ECc at this time, by the formula:

[0075] Qa*ECa+Q1*EC1=Q1+Qa+Qb*ECc, the EC value EC1 in the mother liquid barrel 8 can be obtained:

[0076] EC1=Q1+Qa+Qb*ECc-Qa*ECa / Q1;

[0077] The above process is repeated for multiple mother liquid barrels 8 to respectively measure the EC values ​​EC1, EC2, EC3, ... in each mother liquid barrel 8.

[0078] Repeat this step each time the mother solution is replaced to obtain a new mother solution EC value;

[0079] S3. Set working pressure and EC target value EC T , irrigation time, irrigation duration, proportion of each mother liquor, and field valves that need to be opened; when the irrigation time is reached, first detect whether the premix barrel 7 is at a low water level. If it is a low water level, start the water pump 3 to add water. When the water level reaches 40 cm or is not a low water level, start the irrigation pump 21, adjust the main pipe pressure to the set working pressure, detect the EC value in the premix barrel 7, if it is greater than the set value, continue to add water, if it is less than the set value, adjust each fertilizer suction solenoid valve 11 to suck fertilizer according to the set ratio, so that the EC value in the premix barrel 7 reaches the set value, and pre-prepare the EC value of water and fertilizer in the premix barrel 7;

[0080] S4. When the EC value in the premix barrel 7 reaches the set value, the field plot solenoid valve 13 is opened and the timing is performed, and the irrigation pump 21 is adjusted by the controller 5 so that the working pressure sensor 14 reaches the set value. During the irrigation process, the controller 5 makes the water pump 3 flow rate and the irrigation pump 21 flow rate consistent;

[0081] During fertilization, the real-time main flow Q is obtained through the main flow meter 15, the fertilizer suction flow meter 10 and the water addition flow meter 4. M , Fertilization flow Q F and water addition flow Q S, the water flow rate will be consistent with the main pipeline flow rate, so the water flow rate is used as the calculation basis, according to the target EC value EC set by the user T With the known mother liquor EC value and the set ratio, the duty cycle of the fertilizer suction solenoid valve 11 can be calculated according to the following formula:

[0082] Qxi=(ki / k1+……+kn)EC T *Q S / EC z

[0083] di=f(Qxi)

[0084] Where Qxi is the fertilizer suction flow rate of the i-th fertilizer suction pipe, k1...kn is the fertilizer suction ratio between n fertilizer suction pipes, EC T is the target EC value, Q S is the water addition flow rate, EC z is the combined EC value of each mother liquid, di is the duty cycle of the i-th fertilizer absorption solenoid valve 11 at the target EC value, and f is the functional relationship between the flow rate of the fertilizer absorption solenoid valve 11 and the duty cycle;

[0085] During operation, the duty cycle of each fertilizer suction solenoid valve 11 is directly assigned in real time, so that the EC value of the water and fertilizer application control system can be quickly adjusted to the target EC value after operation. When the EC value is within the range of ±3% of the target value, PID regulation is enabled to achieve rapid stabilization, and the EC value of the water and fertilizer entering the field is within the set value range at all times;

[0086] During operation, when the water level in the premix tank 7 is high, the water pump 3 is stopped; when the water level is low, the irrigation pump 21 is stopped; when the water level in the water storage tank 2 is low, the water pump 3 is stopped; when the water level in the mother liquid tank 8 is low, the fertilizer solenoid valve 11 is stopped, and an alarm is sounded; when the irrigation time is reached, the fertilizer solenoid valve 11, water pump 3, and irrigation pump 21 are stopped; after 5 seconds, the field plot solenoid valve 13 is closed, and the system ends operation.

[0087] In a further embodiment, a pressure reducing valve 18 is provided at the inlet of the fertilization pipeline, and a pressure holding valve 17 is provided on the main pipeline at the rear of the pressure reducing valve 18 .

[0088] Through the above technical solution, the higher pressure of the main pipeline is reduced to a set lower pressure through the pressure reducing valve 18, and no matter what the main pipeline pressure is, it can be kept constant, so that the operating environment of the fertilizer pipeline remains consistent; when the solenoid valve 13 in the field area is opened, the main pipeline pressure between the irrigation pump 21 and the pressure holding valve 17 can be maintained at the set value, ensuring that the pressure reducing valve 18 and the fertilizer pipeline have sufficient working pressure, so that the operating environment of the fertilizer pipeline remains consistent, wherein the pressure reducing valve 18 and the pressure holding valve 17 are electrically connected to the controller 5.

[0089] In a further embodiment, a main pipe pressure sensor 20 is provided on the main pipe in front of the pressure-sustaining valve 17 .

[0090] Through the above technical solution, the pipeline pressure between the irrigation pump 21 and the pressure reducing valve 18 and the pressure holding valve 17 is measured by the main pipe pressure sensor 20. This pressure is used to monitor the pressure in the main pipe when the field area solenoid valve 13 is not opened, wherein the main pipe pressure sensor 20 is electrically connected to the controller 5.

[0091] The preferred specific embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above specific embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the scope of protection of the present invention.

Claims

1. A premixed fertilization system, characterized in that: Including water and fertilizer preparation system, field fertilization system and water and fertilizer application control system; The water-fertilizer preparation system comprises a water adding mechanism, a conveying mechanism and a fertilizer absorbing mechanism, wherein the water adding mechanism comprises a water storage barrel (2), a water adding pump (3) and a premixing barrel (7), wherein the water suction end of the water adding pump (3) is connected to the water storage barrel (2) via a water delivery pipe, and the water discharge end of the water adding pump (3) is connected to the premixing barrel (7) via a water delivery pipe; The conveying mechanism includes an irrigation pump (21), the water suction end of the irrigation pump (21) is connected to the premixing barrel (7), the water discharge end of the irrigation pump (21) is connected to the main pipeline, the main pipeline is connected to a fertilizer pipeline, one end of the fertilizer pipeline is connected to the premixing barrel (7), and the fertilizer suction mechanism is arranged on the fertilizer pipeline; The fertilizer suction mechanism includes a plurality of fertilizer suction pipes arranged in the middle section of the fertilizer pipe, the middle section of the fertilizer suction pipe is connected to a fertilizer venturi pipe (12), and one side of the fertilizer suction pipe is provided with a fertilizer mother liquid suction mechanism connected to the fertilizer venturi pipe (12) in a one-to-one correspondence; The field fertilization system comprises a plurality of field plot fertilization pipes connected to the main pipeline, and the field plot fertilization pipes are provided with field plot solenoid valves (13); The water and fertilizer application control system is used to measure the initial water volume and the initial EC value of the water and fertilizer in the premix barrel (7), and pre-configure the EC value of the water and fertilizer in the premix barrel (7) through the water adding mechanism, the conveying mechanism and the fertilizer mother liquid suction mechanism, so as to ensure that the EC value of the water and fertilizer entering the field is within the set value range at all times.

2. A premix fertilization system according to claim 1, characterized in that: The fertilizer mother liquid suction mechanism comprises a mother liquid barrel (8) arranged on one side of the fertilizer suction pipe, a stirring motor (9) is provided on the top of the mother liquid barrel (8), and an output end of the stirring motor (9) extends into the mother liquid barrel (8) and is connected to the stirring mechanism; The mother liquid barrel (8) is communicated with an adjacent fertilizing venturi tube (12) via a liquid suction pipe, and a fertilizer suction flow meter (10) and a fertilizer suction electromagnetic valve (11) are provided on the liquid suction pipe.

3. A premix fertilization system according to claim 2, characterized in that: The water and fertilizer application control system comprises a controller (5) arranged outside the premixing barrel (7), an EC sensor (16) and a fertilizer pressure sensor (19) arranged on the fertilizer pipeline and located in front of the fertilizer suction pipe, wherein the EC sensor (16) and the fertilizer pressure sensor (19) are both electrically connected to the controller (5).

4. A premix fertilization system according to claim 3, characterized in that: A water tank low water level sensor (1) is provided in the water tank (2), a water flow meter (4) is installed on the water delivery pipe at the outlet end of the water pump (3), and a premixing tank water level meter (6) is provided in the premixing tank (7).

5. A premix fertilization system according to claim 4, characterized in that: The main pipeline is provided with a main flow meter (15).

6. The premix fertilization system according to claim 5, characterized in that: A working pressure sensor (14) is provided on the main pipeline at the front of the field plot fertilizer pipe.

7. The premix fertilization system according to claim 6, characterized in that: The controller (5) includes a water pump frequency converter and an irrigation pump frequency converter, wherein the water pump frequency converter and the irrigation pump frequency converter are electrically connected to the water pump (3) and the irrigation pump (21) respectively; The controller (5) is also electrically connected to the water adding pump (3), the irrigation pump (21), the fertilizing venturi tube (12), the fertilizer suction flow meter (10), the fertilizer suction solenoid valve (11), the water adding flow meter (4), the main flow meter (15) and the working pressure sensor (14).

8. A premixed fertilization control method according to claim 7, characterized in that: The steps include: S1. Start the irrigation pump (21). After the pressure stabilizes for 10 seconds, open a fertilizer suction solenoid valve (11) to suck a certain amount of mother liquid from the mother liquid barrel (8) and then close it. After the EC value of the fertilization pipeline stabilizes for 5 seconds, record the EC sensor (16) value ECa at this time. This value is the initial EC value of the water and fertilizer in the premix barrel (7); Turn on the water pump (3) to add water to the premixing barrel (7). After the amount of water added (Qb) is calculated by the water flow meter (4), wait until the EC value of the fertilizer pipeline is stable, and then record the value ECb of the EC sensor (16). The formula is: (Qa+Qb)*ECb=Qa*ECa, the initial water volume Qa in the premixing tank (7) can be obtained: Qa=Qb*ECb / (ECa-ECb) Where: Qa is the initial water volume in the premixing barrel (7), Qb is the amount of water added to the premixing barrel (7), ECa is the initial EC value of the water and fertilizer in the premixing barrel (7), ECb is the EC value of the water and fertilizer in the premixing barrel (7) after adding water, and the initial EC value of the water and fertilizer in the premixing barrel (7) and the initial water volume Qa are measured; S2. Open the fertilizer suction solenoid valve (11) in one of the mother liquid barrels (8) and inject the fertilizer liquid amount Q1 into the premix barrel (7). Q1 can be measured by the water flow meter (4). After the EC value of the fertilizer pipeline stabilizes, record the value ECc of the EC sensor (16) at this time. The formula is: Qa*ECa+Q1*EC1=(Q1+Qa+Qb)*ECc, the EC value EC1 in the mother liquid barrel (8) can be obtained: EC1=((Q1+Qa+Qb)*ECc-Qa*ECa) / Q1; The above process is repeated for multiple mother liquid barrels (8) to respectively measure the EC values ​​EC1, EC2, EC3, ... in each mother liquid barrel (8). Repeat this step each time the mother solution is replaced to obtain a new mother solution EC value; S3. Set working pressure and EC target value EC T , irrigation time, irrigation duration, proportion of each mother liquor, and field valves to be opened; when the irrigation time is reached, first detect whether the premix barrel (7) is at a low water level, and if it is at a low water level, start the water pump (3) to add water, and when the water level reaches 40 cm or is not at a low water level, start the irrigation pump (21), adjust the main pressure frequency conversion to the set working pressure, detect the EC value in the premix barrel (7), if it is greater than the set value, continue to add water, and if it is less than the set value, adjust each fertilizer suction solenoid valve (11) to suck fertilizer according to the set ratio, so that the EC value in the premix barrel (7) reaches the set value, and the EC value of water and fertilizer in the premix barrel (7) is pre-prepared; S4. When the EC value in the premix barrel (7) reaches the set value, the field plot solenoid valve (13) is opened and the time is set. The irrigation pump (21) is adjusted by the controller (5) so that the value of the working pressure sensor (14) reaches the set value. During the irrigation process, the flow rate of the water pump (3) and the flow rate of the irrigation pump (21) are consistent through the controller (5); During fertilization, the real-time main flow Q is obtained through the main flow meter (15), the fertilizer suction flow meter (10) and the water addition flow meter (4). M , Fertilization flow Q F and water flow rate Q S , the water flow rate will be consistent with the main pipeline flow rate, so the water flow rate is used as the calculation basis, according to the target EC value EC set by the user T With the known mother liquor EC value and the set ratio, the duty cycle of the fertilizer suction solenoid valve (11) can be calculated according to the following formula: Qxi=(ki / (k1+……+kn))EC T *Q S / EC z di=f(Qxi) Where Qxi is the fertilizer suction flow rate of the i-th fertilizer suction pipe, k1...kn is the fertilizer suction ratio between n fertilizer suction pipes, EC T is the target EC value, Q S is the water addition flow rate, EC z is the combined EC value of each mother liquor, di is the duty cycle of the i-th fertilizer absorption solenoid valve (11) at the target EC value, and f is the functional relationship between the flow rate of the fertilizer absorption solenoid valve (11) and the duty cycle; During operation, the duty cycle of each fertilizer suction solenoid valve (11) is directly assigned in real time, so that the EC value of the water and fertilizer application control system can be quickly adjusted to the target EC value after operation. When the EC value is within the range of ±3% of the target value, PID adjustment is enabled to achieve rapid stabilization, and the EC value of the water and fertilizer entering the field is within the set value range at all times; S5. During operation, when the water level in the premixing tank (7) is high, the water pump (3) is stopped; when the water level is low, the irrigation pump (21) is stopped; when the water level in the water storage tank (2) is low, the water pump (3) is stopped; when the water level in the mother liquid tank (8) is low, the fertilizer solenoid valve (11) is stopped, and an alarm is sounded; when the irrigation time is reached, the fertilizer solenoid valve (11), the water pump (3), and the irrigation pump (21) are stopped; after 5 seconds, the field plot solenoid valve (13) is closed, and the system ends operation.

9. The premix fertilization system according to claim 1, characterized in that: A pressure reducing valve (18) is provided at the inlet of the fertilizing pipeline, and a pressure holding valve (17) is provided on the main pipeline at the rear of the pressure reducing valve (18).

10. The premix fertilization system according to claim 9, characterized in that: A main pipe pressure sensor (20) is provided on the main pipe in front of the pressure-holding valve (17).

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