CN115443891B - A method and device for automatically adjusting drip irrigation flow according to solar radiation intensity - Google Patents

Abstract

The invention discloses a method for automatically adjusting drip irrigation flow according to solar radiation intensity. Photovoltaic components drive a water pump to press irrigation water into an irrigation pipe network. The irrigation pipe network is composed of multiple irrigation branch pipes. Measurement and control is installed at the water inlet of each irrigation branch pipe. Integrated valve, integrated measurement and control valve adjusts the flow and pressure of the water delivery main pipe and irrigation branch pipes by changing the valve opening. When the intensity of solar radiation is high, multiple integrated measurement and control valves are automatically opened to increase the number of irrigation branch pipes, thus increasing the irrigation area. To achieve the purpose of making full use of excess irradiation intensity; when the intensity of solar irradiation is small, some valves are automatically closed to increase pipeline pressure to meet the pressure demand for irrigation. This invention uses solar energy as the irrigation power, and uses intelligent measurement and control integrated valves to adjust the flow and pressure of the irrigation pipeline under different irradiation intensities, realizing automatic adjustment of the flow and pressure of the irrigation pipe network, meeting the irrigation needs of the irrigation area, and improving the overall photovoltaic water pump Energy efficiency of lifting and drip irrigation systems.

Description

A method and device for automatically adjusting drip irrigation flow according to solar radiation intensity

Technical field

The invention belongs to the field of agricultural water-saving irrigation and efficient utilization of renewable energy in dry areas, and particularly relates to a method and device for automatically adjusting drip irrigation flow according to solar radiation intensity.

Background technique

In recent years, photovoltaic drip irrigation systems have made great progress in remote farmland irrigation without power supply, which is the development trend of agricultural irrigation in the future. However, solar energy has unstable and intermittent characteristics, which makes the photovoltaic drip irrigation system unable to work normally under stable voltage, especially When the intensity of solar radiation is weak, the pressure of the irrigation pipeline cannot meet the working needs of the drippers. When the intensity of radiation is high, due to the limitations of the irrigation area and irrigation devices, the excess energy cannot be fully utilized, resulting in extremely poor energy utilization of the photovoltaic drip irrigation system. Low. In view of the low overall efficiency of the current photovoltaic drip irrigation system and insufficient utilization of solar energy, some scholars have considered installing energy storage equipment such as batteries and reservoirs, which has resulted in high system costs. Batteries can easily pollute the environment, which is contrary to the original intention of solar clean energy. The flow rate of the photovoltaic irrigation system is uncontrollable, resulting in the current low degree of automation of the photovoltaic drip irrigation system, high water and energy consumption, and difficulty in promotion. Therefore, there is an urgent need for a photovoltaic drip irrigation device that can automatically adjust pipeline flow according to solar radiation intensity to solve the problems of low energy utilization of photovoltaic drip irrigation systems and insufficient intelligence of the irrigation system.

Contents of the invention

In view of the current problems of low energy utilization, uncontrollable flow, and low intelligence of photovoltaic drip irrigation systems, the present invention provides a method for automatically adjusting drip irrigation flow according to solar radiation intensity. This method uses an automatic adjustment valve according to solar radiation intensity. Opening, reduce branch pipe flow, increase branch pipe pressure, increase the working range of the photovoltaic water pump, increase the irrigation water volume of the photovoltaic water pump water lifting system, and achieve micro-regulation of irrigation branch pipe flow.

To achieve the above tasks, the present invention adopts the following technical solutions: a method for automatically adjusting drip irrigation flow according to solar radiation intensity, converting solar energy into electrical energy through photovoltaic components to provide power for photovoltaic water pumps, and integrating measurement and control through PLC control in the PLC valve control system The valve opening is determined by establishing a mathematical model between the valve opening of the integrated measurement and control valve under different irradiation intensities and solar irradiation intensity, water pump flow and lift, and inputting it into the PLC controller. According to different irrigation pipeline pressure requirements, The pressure sensor is detected and fed back to the PLC controller. The opening of the valve to which the valve should be adjusted is calculated through the mathematical model and the target pressure to achieve precise adjustment of the pipeline flow of the drip irrigation system.

The mathematical model between the valve opening of the measurement and control integrated valve and solar radiation intensity, water pump flow rate and lift under different irradiation intensities is as follows:

The relationship between the output power per unit area of photovoltaic modules and solar radiation intensity is determined as shown in formula (1):

P _a = ₁ G (1)

In the formula, P _a is the output power of the photovoltaic module per unit area, W; η ₁ is the conversion efficiency of the photovoltaic module. The output power of the photovoltaic module is related to its area.

The output power of photovoltaic modules can be calculated by formula (2):

P=S _p P _a (2)

In the formula, P is the output power of the photovoltaic module in the test, W; S _p is the panel area of the photovoltaic module, m ² .

When the output power of the photovoltaic module is fixed, the lift and flow rate of the water pump are inversely proportional to each other, and the photovoltaic water pump efficiency η ₂ satisfies equation (3):

In the formula, ρ is the density of water, with a value of 1×10 ³ kg/m ³ ; g is the acceleration of gravity, with a value of 9.8m ² /s; Q is the flow rate of the water pump, m ³ /s; H is the head of the water pump, m.

When the valve is fully open, the lift and flow rate of the photovoltaic water pump and the output power of the photovoltaic module satisfy equations (4) and (5):

Q ₁ ＝a ₁ P ² +b ₁ P+c ₁ (4)

H ₁ =a ₂ P ² +b ₂ P+c ₂ (5)

In the formula, Q ₁ is the flow rate of the photovoltaic water pump when the valve is fully open, L/h; H ₁ is the lift of the photovoltaic water pump when the valve is fully open, m; a ₁ , a ₂ , b 1 , b _{2 ,} c ₁ , c ₂ are model parameters , related to pipeline size and valve type.

The head-valve opening model and the flow-valve opening model satisfy the logistic regression equation, whose forms are as shown in equations (4) and (5):

In the formula, H _n and Q _n are the pressure and flow rate at the water inlet of the pipeline respectively; A ₁ , A ₂ , X ₀ and m are model parameters. As the input power of the photovoltaic water pump changes, the values of the four parameters change regularly at the same time. ;k is the valve opening.

Another object of the present invention is to provide a device that automatically adjusts drip irrigation flow according to solar radiation intensity, including a reservoir, a photovoltaic water pump, a photovoltaic module, an irrigation main pipe, a PLC valve control system, wires, an integrated measurement and control valve, and an irrigation pipe network , irrigation branch pipe, pressure-compensated dripper, the photovoltaic water pump is installed next to the reservoir, the photovoltaic water pump has a built-in MPPT solar controller, and its water outlet is connected to one end of the irrigation main pipe; the other end of the irrigation main pipe It is connected to the irrigation pipe network; there are several branch pipes evenly distributed on the irrigation pipe network, each branch pipe is connected to the water inlet of the integrated measurement and control valve, and the water outlet of the integrated measurement and control valve is connected to the irrigation branch pipe; the irrigation branch pipe There are several pressure compensated drippers installed on it.

The photovoltaic module provides a power source for the photovoltaic water pump through the MPPT solar controller.

The measurement and control integrated valve is composed of a motor, a screw, a plunger guide rail, a plunger, a rubber cushion, a fixing nut, a water inlet shrink tube, a valve body shell, a valve body water inlet pipe, and a valve body water outlet. The valve body A motor is installed on the top of the casing, a valve body water inlet pipe is provided at the lower end, and a valve body water outlet is provided at the middle end. The power shaft of the motor is connected to the upper end of the screw, and the lower end of the screw passes through the plunger guide rail and is connected with the plunger guide rail. The built-in threaded connection of the upper end of the plunger is installed in the plunger guide rail. The plunger guide rail is fixedly installed in the valve body shell. The lower end of the plunger is installed with a rubber cushion through a fixing nut; the valve body The water inlet pipe is provided with a water inlet shrink tube on one end located in the valve body shell.

The PLC valve control system is composed of a PLC controller, a pressure sensor and a radiation intensity-valve opening mathematical model. The PLC controller is connected to the motor, pressure sensor and photovoltaic component of the measurement and control integrated valve through wires.

Furthermore, the device for automatically adjusting the flow rate of drip irrigation according to the intensity of solar radiation is characterized in that a rubber cushion is installed at the lower end of the plunger corresponding to the water inlet shrink tube.

Furthermore, the device for automatically adjusting drip irrigation flow according to solar radiation intensity is characterized in that the plunger can move linearly on the plunger guide rail driven by the screw.

The invention adopts an angle-type measurement and control integrated valve, which is installed at the water inlet of the branch pipe of the irrigation pipe network of the photovoltaic water pump water lifting system. According to the demand for irrigation pressure of the branch pipe, the opening of the valve is adjusted to ensure that under different irradiation intensities, The purpose of normal operation of the irrigation pipe network; through the above mathematical model of radiation intensity-valve opening, the optimal opening of the valve under different irradiation intensity and target pressure can be calculated, and it can be regulated in real time to improve the overall efficiency of the system while achieving The irrigation flow is controllable, providing technical support for the intelligentization and greening of smart agriculture.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention uses an integrated measurement and control valve to control the flow of branch pipes in the water delivery pipe network of the photovoltaic water pump water lifting system. When the intensity of solar radiation is small, the opening of the valve is automatically adjusted to reduce the flow of the branch pipes, increase the pressure of the branch pipes, and increase the work of the photovoltaic water pump. interval, increase the irrigation water volume of the photovoltaic water pump water pumping system, and achieve micro-regulation of the flow of irrigation branch pipes.

2. The present invention uses an integrated measurement and control valve to control the opening and closing of each irrigation branch pipe. When the solar radiation intensity is high, the number of irrigation branch pipes is controlled by adjusting the valve opening and closing, thereby increasing the irrigation area and ensuring that the pressure-compensated drippers on the branch pipes are normal every day. Under the premise of working, increase the number of irrigation branch pipes and improve the full utilization of solar energy. According to the changing characteristics of irradiation intensity, carry out zoned irrigation within a day to ensure uniform irrigation and further optimize the working range of the photovoltaic water pump, which is suitable for photovoltaic drip irrigation. Systematic macro-control of large-area irrigation areas.

3. Based on the characteristics of the measurement and control integrated valve, the present invention establishes a mathematical model of radiation intensity-valve opening. For micro-control and micro-control of the flow and pressure of the irrigation pipe network, under different solar radiation intensities, according to the branch pipe and Based on the working pressure requirements of the pressure-compensated dripper, the PLC controller monitors the data through the pressure sensor and determines the optimal valve opening to maximize the solar energy utilization of the photovoltaic drip irrigation system and further improve the efficiency of the entire system.

Description of the drawings

Figure 1 is a schematic diagram of the overall structure of the device of the present invention;

Figure 2 is a schematic structural diagram of the integrated measurement and control valve;

Figure 3 is a schematic diagram of the equipment connection of the photovoltaic drip irrigation device that automatically adjusts the pipeline flow according to the intensity of solar radiation;

Figure 4 is a schematic diagram of the device control and adjustment method;

Figure 5 is a schematic diagram of the relationship between irradiation intensity per unit area and photovoltaic module output power;

Figure 6 is a schematic diagram of the relationship between the valve opening and the flow rate of the photovoltaic water pump under different irradiation intensities;

Figure 7 is a schematic diagram of the relationship between the valve opening and the lift of the photovoltaic water pump under different irradiation intensities;

Figure 8 is a schematic diagram of the changes in irrigation flow rate before and after optimization of a single irrigation pipeline under different irrigation loads;

Figure 9 is a schematic diagram of the changes in the working number of different irrigation branch pipes with solar radiation intensity on a sunny day.

The numbers in the figure represent: 1-reservoir, 2-photovoltaic water pump, 3-photovoltaic module, 4-irrigation main pipe, 5-PLC valve control system, 6-wire, 7-measurement and control integrated valve, 8-irrigation pipe network, 9 -Irrigation branch pipe, 10-pressure compensated dripper, 51-PLC controller, 52-pressure sensor, 71-motor, 72-screw, 73-plunger guide rail, 74-plunger, 75-rubber cushion, 76- Fixing nut, 77-water inlet shrink tube, 78-valve body shell, 79-valve body water inlet, 710-valve body water outlet.

Detailed ways

The ending solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

Example 1

A method of automatically adjusting the drip irrigation flow rate according to the intensity of solar radiation. The valve opening of the integrated measurement and control valve is controlled by the PLC in the PLC valve control system. By establishing the relationship between the valve opening of the integrated measurement and control valve and the intensity of solar radiation under different irradiation intensities, The mathematical model between the water pump flow and head is input into the PLC controller. According to the pressure requirements of different irrigation pipelines, the pressure sensor is detected and fed back to the PLC controller. The mathematical model and the target pressure are used to calculate the valve to which the valve should be adjusted. According to the opening condition, the pipeline flow rate of the drip irrigation system can be accurately adjusted. The micro-control process is shown in Figure 4a.

The mathematical model between the valve opening of the measurement and control integrated valve under different irradiation intensities and the solar irradiation intensity, water pump flow rate and head is as follows.

Convert solar energy into electricity through photovoltaic modules to power photovoltaic water pumps

The relationship between the output power per unit area of photovoltaic modules and solar radiation intensity is determined as shown in formula (1):

P _a = ₁ G (1)

In the formula, P _a is the output power of the photovoltaic module per unit area, W; η ₁ is the conversion efficiency of the photovoltaic module. The output power of the photovoltaic module is related to its area.

The output power of photovoltaic modules can be calculated by formula (2):

P=S _p P _a (2)

In the formula, P is the output power of the photovoltaic module in the test, W; S _p is the panel area of the photovoltaic module, m ² , and the value here is 3m ² ;

When the output power of the photovoltaic module is fixed, the lift and flow rate of the water pump are inversely proportional to each other, and the photovoltaic water pump efficiency η ₂ satisfies equation (3):

In the formula, ρ is the density of water, with a value of 1×10 ³ kg/m ³ ; g is the acceleration of gravity, with a value of 9.8m ² /s; Q is the flow rate of the water pump, m ³ /s; H is the head of the water pump, m.

When the valve is fully open, the lift and flow rate of the photovoltaic water pump and the output power of the photovoltaic module satisfy equations (4) and (5):

Q ₁ ＝a ₁ P ² +b ₁ P+c ₁ (4)

H ₁ =a ₂ P ² +b ₂ P+c ₂ (5)

In the formula, Q ₁ is the flow rate of the photovoltaic water pump when the valve is fully open, L/h; H ₁ is the lift of the photovoltaic water pump when the valve is fully open, m; a ₁ , a ₂ , b 1 , b _{2 ,} c ₁ , c ₂ are model parameters , related to pipeline size and valve type.

The head-valve opening model and the flow-valve opening model satisfy the logistic regression equation, whose forms are as shown in equations (6) and (7):

In the formula, H _n and Q _n are the pressure and flow rate at the water inlet of the pipeline respectively; A ₁ , A ₂ , X ₀ and m are model parameters. As the input power of the photovoltaic water pump changes, the values of the four parameters change regularly at the same time. ;k is the valve opening.

Establish a mathematical model of radiation intensity-valve opening from formulas (1) to (7), and establish a precise control model of the pump lift and flow rate as the opening changes. According to the changes in solar radiation intensity, a single irrigation pipe can be realized by controlling the measurement and control integrated valve. Micro-control of road traffic.

For multiple irrigation pipelines, the relationship between the flow rate of irrigation branch pipes and main pipes is shown in Equation (8)

In the formula, n is the number of branch pipes, that is, the number of irrigation area divisions, Q is the flow rate of the _main pipe, which is the flow rate at the outlet of the photovoltaic water pump; Q ₁ , Q ₂ ,..., Q _n are the flow rates at the inlets of each branch pipe respectively.

When the irradiation intensity is high, the flow rate Q of the photovoltaic water pump is _relatively large. Due to the compensation dripper at the irrigation end, the total flow rate of irrigation in the existing pipeline is fixed. By increasing the number of integrated measurement and control valves, the irrigation area can be increased to realize photovoltaic drip irrigation. The redistribution of the system will further improve the solar energy utilization rate of the system. The macro-control process is shown in Figure 4b.

In the embodiment of the present invention, the photovoltaic components select two solar monocrystalline silicon panels with dimensions of 1640mm×982mm×40mm (length*width*thickness) and a rated power of 260W; the photovoltaic water pump adopts the model S243T-30 with a rated power of It is 260W, water pump voltage: DC24v (18v~45v); the measurement and control integrated valve structure is shown in Figure 2. The irradiation intensity-valve opening mathematical model of the valve body was obtained through experiments. The test location was the hydraulic hall of Northwest A&F University in Yangling, Shaanxi. Based on the data of solar irradiation intensity and photovoltaic panel output power, the irradiation intensity per unit area and photovoltaic The component output power piecewise function, its schematic diagram is shown in Figure 5; use the above test device to measure the flow rate and lift of the photovoltaic water pump with different irradiation intensities and different valve openings, and improve the mathematics of formulas (1) to (7) relationship, improve the radiation intensity-valve opening mathematical model, and provide a theoretical basis for micro- and macro-adjustment of the photovoltaic water pump water pumping system. The relationship between the valve opening and the photovoltaic water pump flow and lift under different irradiation intensities is shown in Figures 5 and 6 Show.

The relationship between the output power of photovoltaic modules and solar radiation intensity is determined as Equation (9)

When the valve is fully open, the lift and flow rate of the photovoltaic water pump and the output power of the photovoltaic module satisfy equations (9) and (10):

Q ₁ ＝-0.0190P ² +11.9P+370 (9)

H ₁ =-8.570P ² +0.0760P+0.0876 (10)

The relationship formula between the output power of the photovoltaic module simulator and the photovoltaic water pump flow valve opening model parameters A ₁ , A ₂ , X ₀ , n is shown in Table 1.

In the same way, the relationship between the output power of the photovoltaic module simulator and the photovoltaic water pump lift valve opening model parameters A ₁ , A ₂ , X ₀ , n is shown in Table 2.

Furthermore, the integrated measurement and control valve adopts an angular structure, has a simple flow channel, and is not prone to sedimentation and blockage inside.

Furthermore, the radiation intensity-valve opening mathematical model is derived from experiments, in which the photovoltaic water pump flow rate, lift and valve opening satisfy the logistic regression equation.

Furthermore, the PLC controller is equipped with a radiation intensity-valve opening mathematical model to form a PLC valve control system.

A method of automatically adjusting the drip irrigation flow rate according to the solar radiation intensity of the present invention is based on the normal distribution trend of the radiation intensity of a day. In the morning and afternoon, the radiation intensity is relatively small, and around noon, the radiation intensity is larger. The measurement and control integrated valve adjusts the valve opening. When the radiation intensity is weak in the morning and evening, some irrigation branch pipes are closed to meet the irrigation needs of small-area crops; when the radiation intensity is high at noon, the valve switches of more irrigation branch pipes are opened. To meet the irrigation needs of large-area crops, the macro-control of the pipeline flow of the drip irrigation system can be achieved through alternate irrigation of the irrigation area at different times. The adjustment method is shown in Figure 9. When the radiation intensity is small, the pipeline pressure provided by the photovoltaic water pump is low and cannot meet the minimum working pressure of the dripper. The valve opening is adjusted by the motor to change the flow and pressure in the pipeline. According to the flow-lift during the working process of the water pump ( pressure) relationship curve, the pipeline pressure-flow curve refers to the actual pressure-flow curve in the pipeline under the influence of the valve opening. When these two curves intersect, the water pump can work. Increase the pipeline water pressure by adjusting the valve opening to meet the minimum pressure requirement of the dripper; when the radiation intensity changes slightly, the pipeline flow and pressure can be converted into each other by changing the valve opening. According to the solar radiation intensity, Automatically adjust the valve opening, reduce branch pipe flow, increase branch pipe pressure, increase the working range of the photovoltaic water pump, increase the irrigation water volume of the photovoltaic water pump water lifting system, and achieve micro-regulation of irrigation branch pipe flow, which optimizes the before and after effects under different target pressures As shown in Figure 8.

Example 2

Referring to Figures 1 to 2, a device that automatically adjusts drip irrigation flow according to solar radiation intensity consists of a reservoir 1, a photovoltaic water pump 2, a photovoltaic module 3, an irrigation pipe network 8, a measurement and control integrated valve 7, a PLC valve control system 5, It consists of 6 electric wires, 4 water main pipes, 9 irrigation branch pipes, and 10 pressure-compensated drippers.

The photovoltaic water pump 2 is installed next to the reservoir, and its water outlet is connected to the water delivery pipe network 8; the water delivery pipe network 8 includes a water delivery main pipe 4 and an irrigation branch pipe 9; one end of the water delivery main pipe 4 is connected The other end of the photovoltaic water pump 2 is connected to the irrigation branch pipe to form a water delivery pipe network 8; the water inlet of the irrigation branch pipe 9 is equipped with a measurement and control integrated valve 7 for controlling the flow rate into the irrigation branch pipe 9, and the water outlet is equipped with equally spaced pressure compensation drops. The head 10 is used for field irrigation; the measurement and control integrated valve 7 has a motor 71 installed on the upper end for driving the screw 72. The plunger 74 moves up and down along the plunger guide rail 73, and a rubber cushion 75 is placed on the plunger 74. It is fixed with a nut 76, and a water inlet shrink tube 77 is installed below the fixed nut 76. The above structure is integrated in the valve body shell 78. The lower end of the valve body is the water inlet pipe 79, and the upper end is the water outlet 710.

The PLC valve control system 5 includes a PLC controller 51, a pressure sensor 52 and an irradiation intensity-valve opening mathematical model. The PLC controller 51 is connected to the measurement and control integrated valve 7 and monitors the pressure change of the irrigation branch pipe 9 through the pressure sensor 52. Combined with the radiation intensity-valve opening mathematical model in the PLC controller 51, the valve opening of the measurement and control integrated valve 7 is adjusted to meet the irrigation pressure demand of the irrigation branch pipe 9.

Figure 3 is a schematic diagram of the equipment connection of a photovoltaic drip irrigation device that automatically adjusts pipeline flow according to solar radiation intensity. In the figure, the PLC reads the analog value in the pressure transmitter through the RS485 interface, converts it into pipeline pressure, and brings it into the valve opening model. Calculate the optimal valve opening, control the rotation of the motor in the measurement and control integrated valve through the output ports Y0, Y1, and Y2, and adjust to the calculated valve opening.

The micro-control of the photovoltaic drip irrigation system is to install a pressure-compensated dripper 10 at the end of a single micro-irrigation pipeline. According to irrigation hydraulic calculations, the pipeline must meet the target pressure of irrigation in order to work properly. When the irradiation intensity is low, normal irrigation cannot occur due to insufficient pipeline pressure. By adjusting the valve opening of the measurement and control integrated valve 7 to increase the pipeline pressure, normal irrigation of the irrigation pipe network 8 is achieved. The optimization effect is shown in Figure 8.

The macroscopic adjustment of the photovoltaic drip irrigation system is aimed at multiple irrigation branch pipes 9. When the radiation intensity is high, the opening and closing of the integrated measurement and control valve 7 is adjusted to increase the irrigation area. When the radiation intensity is weak, the integrated measurement and control valve is adjusted to increase the irrigation area. Closing the valve 7 reduces the number of irrigation lines in the irrigation branch pipe 9, thereby reducing the irrigation area. Through the irrigation area in turn, as shown in Figure 9, for the fixed photovoltaic water pump 2, full utilization of solar energy is achieved and the energy of the system is improved. usage efficiency.

The invention discloses a device that automatically adjusts pipeline flow according to solar radiation intensity. Photovoltaic components drive a water pump to press irrigation water into an irrigation pipe network. The irrigation pipe network is composed of multiple irrigation branch pipes and is installed at the water inlet of each irrigation branch pipe. The integrated measurement and control valve adjusts the flow and pressure of the water delivery main pipe and irrigation branch pipes by changing the valve opening. When the intensity of solar radiation is high, multiple integrated measurement and control valves are automatically opened to increase the number of irrigation branch pipes, thereby increasing the irrigation area. , to achieve the purpose of making full use of excess radiation intensity; when the solar radiation intensity is small, some valves are automatically closed to increase pipeline pressure to meet the pressure demand for irrigation. When the solar radiation intensity is low, the flow rate is reduced and the pipeline pressure is increased to meet the pressure demand of the irrigation pipeline; the present invention uses solar energy as irrigation power, and uses an intelligent measurement and control integrated valve to adjust the flow and pressure of the irrigation pipeline under different irradiation intensities to achieve The automatic adjustment of the flow and pressure of the irrigation pipe network meets the irrigation needs of the irrigation area; the device effectively combines the sinusoidal changing characteristics of solar energy and uses the valve opening and closing and opening changes of the measurement and control integrated valve to achieve full and effective utilization of solar energy in different periods. The complementary adjustment method of irrigation flow at macro and micro levels can improve the energy utilization efficiency of the entire photovoltaic water pump drip irrigation system.

Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art will understand that various changes, modifications, and substitutions can be made to these embodiments without departing from the principles and spirit of the invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (4)

1. A method for automatically adjusting drip irrigation flow according to solar radiation intensity, which is characterized by converting solar energy into electrical energy through photovoltaic modules to provide power for photovoltaic water pumps, and controlling the valve opening of the integrated valve through PLC control in the PLC valve control system. By establishing a mathematical model between the valve opening of the measurement and control integrated valve and solar radiation intensity, water pump flow and lift under different irradiation intensities, and inputting it into the PLC controller, according to different irrigation pipeline pressure requirements, the pressure sensor detects and It is fed back to the PLC controller, and the opening of the valve to which it should be adjusted is calculated through the mathematical model and the target pressure to achieve precise adjustment of the pipeline flow of the drip irrigation system; The mathematical model between the valve opening of the measurement and control integrated valve and solar radiation intensity, water pump flow rate and lift under different irradiation intensities is as follows: The relationship between the output power per unit area of photovoltaic modules and solar radiation intensity is determined as shown in formula (1): P _a = ₁ G (1) In the formula, P _a is the output power of the photovoltaic module per unit area, W; η ₁ is the conversion efficiency of the photovoltaic module, and the output power of the photovoltaic module is related to its area; The output power of photovoltaic modules can be calculated by formula (2): P=S _p P _a (2) In the formula, P is the output power of the photovoltaic module in the test, W; S _p is the panel area of the photovoltaic module, m ² ; When the output power of the photovoltaic module is fixed, the lift and flow rate of the water pump are inversely proportional to each other, and the photovoltaic water pump efficiency η ₂ satisfies equation (3): In the formula, ρ is the density of water, with a value of 1×10 ³ kg/m ³ ; g is the acceleration of gravity, with a value of 9.8m ² /s; Q is the flow rate of the water pump, m ³ /s; H is the head of the water pump, m; When the valve is fully open, the lift and flow rate of the photovoltaic water pump and the output power of the photovoltaic module satisfy equations (4) and (5): Q ₁ ＝a ₁ P ² +b ₁ P+c ₁ (4) H ₁ =a ₂ P ² +b ₂ P+c ₂ (5) In the formula, Q ₁ is the flow rate of the photovoltaic water pump when the valve is fully open, L/h; H ₁ is the lift of the photovoltaic water pump when the valve is fully open, m; a ₁ , a ₂ , b 1 , b _{2 ,} c ₁ , c ₂ are model parameters , related to pipeline size and valve type; The head-valve opening model and the flow-valve opening model satisfy the logistic regression equation, whose forms are as shown in equations (4) and (5): In the formula, H _n and Q _n are the pressure and flow rate at the water inlet of the pipeline respectively; A ₁ , A ₂ , X ₀ and m are model parameters. As the input power of the photovoltaic water pump changes, the values of the four parameters change regularly at the same time. ;k is the valve opening. 2. A device that automatically adjusts drip irrigation flow according to solar radiation intensity, characterized by including a reservoir (1), a photovoltaic water pump (2), a photovoltaic module (3), an irrigation main pipe (4), and a PLC valve control system (5), electric wires (6), integrated measurement and control valve (7), irrigation pipe network (8), irrigation branch pipes (9), pressure compensated dripper (10), the photovoltaic water pump (2) is installed in the water storage Next to the pool (1), the photovoltaic water pump (2) has a built-in MPPT solar controller, and its water outlet is connected to one end of the irrigation main pipe (4); the other end of the irrigation main pipe (4) is connected to the irrigation pipe network (8) Connection; there are several branch pipes evenly distributed on the irrigation pipe network (8), each branch pipe is connected with the water inlet of the integrated measurement and control valve (7), and the water outlet of the integrated measurement and control valve (7) is connected with the irrigation branch pipe (7). 9) Connected; several pressure-compensated drippers (10) are installed on the irrigation branch pipe (9); The photovoltaic module (3) provides a power source for the photovoltaic water pump (2) through the MPPT solar controller; The measurement and control integrated valve (7) consists of a motor (71), a screw (72), a plunger guide rail (73), a plunger (74), a rubber cushion (75), a fixing nut (76), and a water inlet shrink tube. (77) is composed of a valve body shell (78), a valve body water inlet pipe (79), and a valve body water outlet (710). The top of the valve body shell (78) is equipped with a motor (71), and the lower end is provided with a valve body. The water inlet pipe (79) has a valve outlet (710) at the middle end. The power shaft of the motor (71) is connected to the upper end of the screw (72). The lower end of the screw (72) passes through the plunger. guide rail (73), and is connected with the built-in thread at the upper end of the plunger (74) installed in the plunger guide rail (73). The plunger guide rail (73) is fixedly installed in the valve body shell (78). The lower end of the plunger (74) is equipped with a rubber cushion (75) through a fixing nut (76); the valve body water inlet pipe (79) is provided with a water inlet shrink tube on one end located in the valve body shell (78) (77); The PLC valve control system (5) is composed of a PLC controller (51), a pressure sensor (52) and a radiation intensity-valve opening mathematical model. The PLC controller (51) is connected to the valve through a wire (6) respectively. The motor (71), pressure sensor (52) and photovoltaic component (3) of the integrated measurement and control valve are connected. 3. A device for automatically adjusting drip irrigation flow according to solar radiation intensity according to claim 2, characterized in that a rubber cushion (75) and a water inlet shrink tube (77) are installed at the lower end of the plunger (74). )Corresponding. 4. A device for automatically adjusting drip irrigation flow according to solar radiation intensity according to claim 2, characterized in that the plunger (74) can be moved on the plunger guide rail (73) under the push of the screw (72). ) moves in a straight line.