Farmland irrigation pipeline leakage point detection system based on microwave impedance

Abstract

The invention discloses a farmland irrigation pipeline leakage point detection system based on microwave impedance, and relates to the technical field of pipeline systems, the farmland irrigation pipeline leakage point detection system comprises a microwave impedance measurement circuit, a coaxial multiplexer, a leakage detection sensing element, a data collector, a wireless data transmission module and a PC terminal, the PC terminal determines the leakage position or the leakage degree of the leakage point according to the reflection signal, and further determines the axial position and the radial position of the leakage point according to the leakage position or the leakage degree. The microwave impedance measuring circuit is used for detecting the leakage point of the farmland irrigation pipeline, the microwave impedance measuring circuit injects a step signal into one end of the leakage detection sensing element, the signal is partially or completely reflected when encountering an impedance mismatching point when propagating along the leakage detection sensing element, and the leakage point of the farmland irrigation pipeline can be detected on the premise that soil is not excavated. Real-time and accurate positioning of the leakage point of the farmland irrigation pipeline can be realized.

Description

Technical Field

[0001] The present application relates to the technical field of pipeline systems, and in particular to a microwave impedance-based farmland irrigation pipeline leakage detection system. Background Art

[0002] Buried irrigation pipes are widely used in automated irrigation of farmland. Their health status plays a vital role in irrigation efficiency, agricultural water metering, and automated collection and measurement of water resource information. There is a huge demand and market for buried pipe inspection. Buried pipes are prone to leakage due to factors such as overload operation and uneven soil settlement. Pipe leakage not only affects irrigation efficiency and wastes water resources, but also causes root damage and rot of crops. Therefore, real-time inspection of buried pipes can provide reliable technical support for the integrity evaluation and operation and maintenance guarantee of the irrigation system, and is an important measure to ensure the safety of farmland irrigation projects and the environment.

[0003] Time domain reflection technology is an effective non-contact detection technology. Through the propagation and reflection of microwaves in the medium, the change of dielectric constant of the medium can be effectively detected. When a buried pipeline leaks, the dielectric constant of the soil near it will change greatly. Therefore, the location of the leakage point can be effectively detected by using reflection technology. For example, CN110410685A discloses a system and method for locating underground pipe network leakage based on time domain reflection technology. The patent sets two parallel detection lines near the pipeline, inputs signals to the detection lines and collects reflected signals. The location of the pipeline leakage can be determined by analyzing the reflected signals.

[0004] However, the above patent can only determine the leakage position of the pipeline in the axial direction, and the diameter of the irrigation pipeline is usually relatively large. Even if the axial leakage position is known, it is difficult to monitor the leakage degree, and it still takes a lot of time and cost to determine the radial position of the leakage point. Therefore, the existing patent has a relatively low monitoring degree and positioning accuracy for the leakage point. Summary of the invention

[0005] The embodiment of the present application provides a microwave impedance-based farmland irrigation pipeline leakage detection system to solve the problem of low accuracy in leakage degree monitoring and leakage point positioning in the prior art.

[0006] The embodiment of the present application provides a farm irrigation pipeline leakage point detection system based on microwave impedance, including a microwave impedance measurement circuit, a coaxial multiplexer, a leakage detection sensor element, a data collector, a wireless data transmission module and a PC terminal, wherein the microwave impedance measurement circuit, the coaxial multiplexer and the leakage detection sensor element are electrically connected in sequence, and the microwave impedance measurement circuit, the data collector and the wireless data transmission module are also electrically connected in sequence, and the microwave impedance measurement circuit generates a microwave signal and transmits it to the leakage detection sensor element through the coaxial multiplexer, and the leakage detection sensor element receives the reflected signal and transmits it to the leakage detection sensor element through the coaxial multiplexer. The device transmits the reflected signal to the microwave impedance measurement circuit. The data collector collects the reflected signal and then transmits it to the PC terminal through the wireless data transmission module. The leakage detection sensor element is a parallel double wire. The leakage detection sensor element is spirally wound on the outer side of the buried pipeline with a uniform pitch. The PC terminal determines the leakage position or leakage degree of the leakage point according to the reflected signal. The leakage position or leakage degree is the position relative to the length of the leakage detection sensor element. The PC terminal also determines the axial position and radial position of the leakage position or leakage degree relative to the buried pipeline according to the leakage position or leakage degree and the pitch.

[0007] In a possible implementation, when the leakage point just starts to leak, the leakage point is a point-shaped area whose leakage area is smaller than the threshold value, and the leakage position is determined according to the following formula:

[0008] in, is the leakage location, is the reflection time of the leakage point, is the initial reflection time, is the end reflection time, The length of the leak detection sensing element.

[0009] In a possible implementation, when the leakage point is a sheet-like area with a leakage area greater than a threshold value due to continuous leakage or large-area leakage, the leakage degree is determined according to the following formula:

[0010] in, is the leakage degree, i.e. the length of the leakage detection sensor element passing through the sheet area, is the reflection time of the leakage detection sensor element entering the leakage point, is the reflection time of the leakage detection sensor element leaving the leakage point, is the initial reflection time, is the end reflection time, The length of the leak detection sensing element.

[0011] In a possible implementation, the axial position of the leakage point is determined according to the following formula:

[0012] in, Y is the axial position, A is the thread pitch, l The length of the leakage detection sensor element wrapped around the buried pipe. Leakage location or leakage degree.

[0013] In a possible implementation, the radial position of the leakage point is determined according to the following formula:

[0014] in, is the radial position, % is the remainder symbol, l The length of the leak detection sensor element wrapped around the buried pipe once.

[0015] In a possible implementation, it also includes a bracket and an equipment box, the bracket is fixed in the base, the equipment box is arranged on the bracket, and the microwave impedance measurement circuit, the coaxial multiplexer, the data collector and the wireless data transmission module are all arranged in the equipment box.

[0016] In a possible implementation, it also includes a solar panel and a lead-acid battery. The solar panel is set on a bracket, and the lead-acid battery is set in an equipment box. The solar panel charges the lead-acid battery, and the lead-acid battery supplies power to the microwave impedance measurement circuit, the data collector and the wireless data transmission module.

[0017] In a possible implementation, the leakage detection sensor element includes a first parallel double-wire conductor and a second parallel double-wire conductor, and the first parallel double-wire conductor and the second parallel double-wire conductor are both coated with a parallel double-wire insulator; the coaxial multiplexer is electrically connected to the leakage detection sensor element through a coaxial cable, and the coaxial cable includes a coaxially arranged coaxial central conductor and a coaxial shielding layer, the coaxial central conductor and the coaxial shielding layer have an insulating medium, and the coaxial shielding layer is coated with a polyvinyl chloride sheath; The first parallel two-wire conductor and the second parallel two-wire conductor are electrically connected to the coaxial line center conductor and the coaxial line shielding layer, respectively.

[0018] The microwave impedance-based farmland irrigation pipeline leakage detection system in this application has the following advantages: In order to accurately locate the leakage point of the farmland irrigation pipeline and get rid of the limitation of the pipe material, this application uses the microwave impedance measurement circuit for the leakage point detection of the farmland irrigation pipeline. The microwave impedance measurement circuit injects a rapidly rising step signal or pulse signal into one end of the leakage detection sensor element. When the signal propagates along the leakage detection sensor element and encounters an impedance mismatch point, it will be partially or completely reflected. Without excavating the soil, the leakage point of the farmland irrigation pipeline can be located in real time and accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A schematic diagram of the composition of a microwave impedance-based farm irrigation pipeline leakage detection system provided in an embodiment of the present application.

[0021] Figure 2 A schematic diagram of the installation status of the microwave impedance-based farmland irrigation pipeline leakage detection system provided in an embodiment of the present application in a farmland.

[0022] Figure 3 A schematic diagram of the composition of the on-site detection component provided in an embodiment of the present application.

[0023] Figure 4 A schematic cross-sectional view of a leakage detection sensor element provided in an embodiment of the present application.

[0024] Figure 5 A schematic cross-sectional view of a coaxial cable provided in an embodiment of the present application.

[0025] Figure 6 A schematic diagram of the principles of axial and radial positioning of a leakage point provided in an embodiment of the present application.

[0026] Explanation of the accompanying symbols: 1. Solar panel; 2. Lead-acid battery; 3. Microwave impedance measurement circuit; 4. Leakage detection sensor element; 5. Coaxial multiplexer; 6. Data collector; 7. Wireless data transmission module; 8. PC terminal; 9. Buried pipeline; 10. Bracket; 11. Equipment box; 12. Base; 13. Backfill soil; 14. Coaxial cable; 15. Leakage point; 16. First parallel double-wire conductor; 17. Second parallel double-wire conductor; 18. Parallel double-wire insulator; 19. Coaxial line center conductor; 20. Coaxial line shielding layer; 21. Insulating medium; 22. Polyvinyl chloride sheath. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0028] Figure 1 A schematic diagram of the composition of a farm irrigation pipeline leakage detection system based on microwave impedance provided in an embodiment of the present application. The embodiment of the present application provides a farm irrigation pipeline leakage detection system based on microwave impedance, including a microwave impedance measurement circuit 3, a coaxial multiplexer 5, a leakage detection sensor element 4, a data collector 6, a wireless data transmission module 7 and a PC (personal computer) terminal 8. The microwave impedance measurement circuit 3, the coaxial multiplexer 5 and the leakage detection sensor element 4 are electrically connected in sequence, and the microwave impedance measurement circuit 3, the data collector 6 and the wireless data transmission module 7 are also electrically connected in sequence. After the microwave impedance measurement circuit 3 generates a microwave signal, it is transmitted to the leakage detection sensor element 4 through the coaxial multiplexer 5. After the leakage detection sensor element 4 receives the reflected signal, it transmits it to the leakage detection sensor element 4 through the wireless data transmission module 7. The coaxial multiplexer 5 transmits the signal to the microwave impedance measurement circuit 3. The data collector 6 collects the reflected signal and transmits it to the PC terminal 8 through the wireless data transmission module 7. The leakage detection sensor element 4 is a parallel double wire. The leakage detection sensor element 4 is spirally wound on the outer side of the buried pipeline 9 with a uniform pitch. The PC terminal 8 determines the leakage position or leakage degree of the leakage point 15 according to the reflected signal. The leakage position or leakage degree is the position relative to the length of the leakage detection sensor element 4. The PC terminal 8 also determines the axial position and radial position of the leakage position or leakage degree relative to the buried pipeline 9 according to the leakage position or leakage degree and the pitch.

[0029] Exemplarily, the microwave signal generated by the microwave impedance measurement circuit 3 is a step signal or a pulse signal. While transmitting the microwave signal to the coaxial multiplexer 5, the microwave impedance measurement circuit 3 will also record the waveform information of the microwave signal, and the waveform information will be collected by the data collector 6. The microwave signal is transmitted to the leakage detection sensor element 4 outside the buried pipeline 9 through the coaxial multiplexer 5. When the microwave signal propagates along the leakage detection sensor element 4, when it encounters the increase in local impedance of the soil caused by leakage, it will cause the microwave signal to be reflected and form a reflection signal. The reflection signal is transmitted back to the microwave impedance measurement circuit 3 through the coaxial multiplexer 5, and the data collector 6 collects the waveform information of the reflection signal and transmits it to the PC terminal 8 through the wireless data transmission module 7.

[0030] Since the data collector 6 also collects the waveform information of the microwave signal, the PC terminal 8 will receive the waveform information of the microwave signal and the waveform information of the reflected signal at the same time. The reflection position of the microwave signal is the dry-wet interface of the soil body through which the leakage detection sensor element 4 passes, and the reflection position can be determined by the transmission rate and reflection time of the microwave signal in the leakage detection sensor element 4. After receiving the waveform information of the microwave signal and the waveform information of the reflected signal, the reflection time caused by the change of the dielectric constant of the soil body in the reflected signal can be determined by comparing the two waveform information. According to the reflection time and the transmission rate of the microwave signal, the distance between the reflection position and a specific position on the leakage detection sensor element 4, such as the position where the leakage detection sensor element 4 is inserted into the soil body, can be obtained. This distance can be used to indicate the position of the leakage point 15, that is, the leakage position or the degree of leakage.

[0031] Further, when the leakage point 15 is a point-shaped area where the leakage area is smaller than the threshold, the leakage position is determined according to the following formula: (1) in, is the leakage point 15 is the leakage position when the leakage area is smaller than the point area generated by the threshold, in meters, is the reflection time of the leakage point 15, in nanoseconds, is the starting reflection time, in nanoseconds, is the end reflection time, in nanoseconds, is the length of the leakage detection sensor element 4, in meters.

[0032] Specifically, the leakage position is the length of the leakage detection sensor element 4 between the position of the leakage detection sensor element 4 at the leakage point 15 and the position where the leakage detection sensor element 4 is inserted into the soil. Since the dielectric constant of the leakage detection sensor element 4 will change suddenly when it is inserted into the soil, at the leakage point 15 and at the end, reflection signals will be generated at these three positions. The leakage position can be determined by analyzing the reflection time corresponding to these reflection signals.

[0033] Furthermore, when the leakage point 15 is a continuous leakage or the leakage area is larger than the sheet area formed by the threshold, the leakage degree is determined according to the following formula: (2) in, is the degree of leakage when the leakage point 15 is continuously leaking or the leakage area is larger than the sheet area formed by the threshold, in meters, that is, the length of the leakage detection sensor element 4 passing through the sheet area, is the reflection time of the leakage detection sensor element 4 entering the leakage point 15, in nanoseconds, is the reflection time of the leakage detection sensor element 4 from the leakage point 15, in nanoseconds, is the starting reflection time, in nanoseconds, is the end reflection time, in nanoseconds, is the length of the leakage detection sensor element 4, in meters.

[0034] Specifically, if the range of the leakage point 15 is relatively large, the leakage detection sensor element 4 will enter the leakage point 15 and leave the leakage point 15. In both cases, a sudden change in the dielectric constant of the soil will occur. Therefore, reflection signals will be generated at the entry and exit positions. The time of these two reflection signals can reflect the starting point and end point of the leakage point 15, that is, the range of the leakage point 15.

[0035] Since the wet area of ​​the soil around the leakage point 15 pipeline gradually increases, the PC terminal 8 can obtain multiple reflection times after comparing the waveform information of the microwave signal and the waveform information of the reflected signal. If there are three reflection times, it means that the leakage point 15 has just started to leak, and the position of the leakage point 15 can be determined. If the reflection time is four, it means that the wet area of ​​the soil around the leakage point 15 increases, and the corresponding leakage degree can be determined according to the different reflection times. Of course, the reflection time may also be other numbers. If it is more than four, it means that there is more than one leakage point 15, and the number of leakage points 15 on the pipeline can be judged according to the specific situation of the reflection time.

[0036] Furthermore, the axial position is determined according to the following formula: (3) in, Y is the axial position in meters, A is the pitch in meters, l is the length of the leakage detection sensor element 4 wrapped around the buried pipe 9, in meters. is the leakage position or leakage degree, in meters. When the leakage point 15 is a point, the leakage position or leakage degree The value is , and when the leakage point 15 is in the form of a sheet, the leakage position or degree The value is .

[0037] Specifically, l It can be calculated by the following formula: (4) in, R is the outer radius of the buried pipeline 9, in meters.

[0038] Furthermore, the radial position is determined according to the following formula: (5) in, is the radial position, unit is degree, % is the remainder symbol, Indicates the location or extent of leakage Divide by length l The remainder after l It is the length of the leakage detection sensor element 4 wrapped around the buried pipeline 9 once, in meters.

[0039] The method of using the detection system in the embodiment of the present application is as follows: In the first step, before burying the buried pipeline 9, a parallel double wire is continuously wound and fixed in a spiral shape with a uniform pitch on the outer surface of the buried pipeline 9 as a leakage detection sensor element 4.

[0040] The second step is to connect one end of each leakage detection sensor element 4 to a connection end of the coaxial multiplexer 5. The coaxial multiplexer 5 in the present application has multiple connection ends, each of which is used to connect a leakage detection sensor element 4. Since each leakage detection sensor element 4 is wound around a buried pipe 9, the coaxial multiplexer 5 can provide microwave signals to multiple buried pipes 9 at the same time and receive reflected signals. In the embodiment of the present application, the length of each leakage detection sensor element 4 is relatively short. Therefore, it is necessary to sequentially set multiple leakage detection sensor elements 4 on a longer buried pipe 9. Each leakage detection sensor element 4 is used to detect one end of the buried pipe 9. Multiple leakage detection sensor elements 4 arranged sequentially can cover the entire length of the buried pipe 9. Figure 2 As shown. This short-length multi-segment detection method can avoid the serious attenuation and dispersion of microwave signals in the leakage detection sensor element 4 due to long-distance transmission to a certain extent, and improve the accuracy of the detection result. The coaxial multiplexer 5 switches the connected leakage detection sensor element 4 under the control of the microwave impedance measurement circuit 3, and controls the microwave signal output and reflection signal input of each leakage detection sensor element 4 in turn in a polling manner.

[0041] The third step is to connect the other end of the coaxial multiplexer 5 to the microwave impedance measurement circuit 3.

[0042] In the fourth step, the soil 13 is backfilled around the buried pipeline 9, and the buried pipeline 9 is run with water.

[0043] In the fifth step, a microwave signal is sent to the leakage detection sensor element 4 through the microwave impedance measurement circuit 3. The microwave signal is transmitted in the leakage detection sensor element 4 and completely reflected at the end. The data collector 6 collects the waveform information of the microwave signal and the reflected signal, and sends it to the PC terminal 8 through the wireless data transmission module 7. The waveform information obtained by the data collector 6 is observed at the PC terminal 8. If a certain position of the buried pipeline 9 under inspection leaks, the water content of the soil around the leakage point 15 increases, causing the dielectric constant of the local soil at the leakage point 15 to change, causing the microwave signal transmitted in the leakage detection sensor element 4 to be reflected, and the position where the buried pipeline 9 leaks is located according to equations (1)-(2).

[0044] In the sixth step, the leakage position or leakage degree located by the microwave impedance measurement circuit 3 is a linear distance, and the arrangement of the leakage detection sensor element 4 is to be spirally wound with a uniform pitch and fixed on the outer surface of the buried pipeline 9. This arrangement is to determine the radial leakage position or leakage degree of the pipeline while determining the axial leakage position or leakage degree of the pipeline. For axial positioning, since each point on the uniform spiral line has a one-to-one correspondence with the projection position of the spiral line on the pipe axis, as shown in equations (3)-(4), the axial positioning of the leakage point 15 is achieved through this correspondence. For radial positioning, the projection position of the point on each circle of the spiral line on the pipe cross section is also a one-to-one correspondence, as shown in equations (5) and Figure 6 , the radial positioning of the leakage point 15 is achieved through this corresponding relationship.

[0045] In a possible embodiment, it also includes a bracket 10 and an equipment box 11, the bracket 10 is fixed in the base 12, the equipment box 11 is arranged on the bracket 10, and the microwave impedance measurement circuit 3, the coaxial multiplexer 5, the data collector 6 and the wireless data transmission module 7 are all arranged in the equipment box 11.

[0046] For example, the bracket 10 is a cylindrical rod, and the equipment box 11 is fixed by welding to the side of the bracket 10 near the upper end. The base 12 is a concrete block, which is a prefabricated part. The screws for installing the bracket 10 have been pre-buried during the production. When in use, the base 12 is transported and buried on the ground near the buried pipeline 9, and then the bracket 10 is installed on the base 12.

[0047] In a possible embodiment, it also includes a solar panel 1 and a lead-acid battery 2, the solar panel 1 is arranged on a bracket 10, the lead-acid battery 2 is arranged in an equipment box 11, the solar panel 1 charges the lead-acid battery 2, and the lead-acid battery 2 supplies power to the microwave impedance measurement circuit 3, the data collector 6 and the wireless data transmission module 7.

[0048] For example, in addition to solar power generation, other forms of power sources, such as wind power generation or city electricity, can be integrated on the bracket 10, so that when the solar panel 1 cannot generate electricity normally due to weather reasons, the backup power supply can continue to charge the lead-acid battery 2, and the lead-acid battery 2 can then provide a stable 12V DC power supply to the microwave impedance measurement circuit 3, the data collector 6 and the wireless data transmission module 7, ensuring that the detection system can operate stably and continuously.

[0049] In a possible embodiment, the leakage detection sensor element 4 includes a first parallel double-wire conductor 16 and a second parallel double-wire conductor 17, and the first parallel double-wire conductor 16 and the second parallel double-wire conductor 17 are both coated with a parallel double-wire insulator 18; the coaxial multiplexer 5 is electrically connected to the leakage detection sensor element 4 through a coaxial cable 14, and the coaxial cable 14 includes a coaxially arranged coaxial line center conductor 19 and a coaxial line shielding layer 20, the coaxial line center conductor 19 and the coaxial line shielding layer 20 have an insulating medium 21, and the coaxial line shielding layer 20 is coated with a polyvinyl chloride sheath 22; the first parallel double-wire conductor 16 and the second parallel double-wire conductor 17 are electrically connected to the coaxial line center conductor 19 and the coaxial line shielding layer 20 respectively.

[0050] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0051] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A microwave impedance-based agricultural irrigation pipeline leakage detection system, comprising a microwave impedance measurement circuit (3), a coaxial multiplexer (5), a leakage detection sensor element (4), a data collector (6), a wireless data transmission module (7) and a PC terminal (8), wherein the microwave impedance measurement circuit (3), the coaxial multiplexer (5) and the leakage detection sensor element (4) are electrically connected in sequence, and the microwave impedance measurement circuit (3), the data collector (6) and the wireless data transmission module (7) are also electrically connected in sequence, wherein the microwave impedance measurement circuit (3) generates a microwave signal and transmits it to the leakage detection sensor element (4) through the coaxial multiplexer (5), and the leakage detection sensor element (4) receives a reflected signal and transmits it to the microwave impedance measurement circuit (3) through the coaxial multiplexer (5), and the data collector (6) collects the reflected signal and transmits it to the PC terminal (8) through the wireless data transmission module (7), wherein: The leakage detection sensor element (4) is a parallel double wire. The leakage detection sensor element (4) is spirally wound on the outer side of the buried pipeline (9) with a uniform pitch. The PC terminal (8) determines the leakage position or leakage degree of the leakage point (15) according to the reflected signal. The leakage position or the leakage degree is a position relative to the length of the leakage detection sensor element (4). The PC terminal (8) also determines the axial position and radial position of the leakage position or the leakage degree relative to the buried pipeline (9) according to the leakage position or the leakage degree and the pitch.

2. The farmland irrigation pipeline leakage detection system based on microwave impedance according to claim 1 is characterized in that: When the leakage point (15) is a point-shaped area whose leakage area is smaller than the threshold, the leakage position is determined according to the following formula: in, The leakage point (15) is the leakage position when the leakage area is smaller than the point-shaped area generated by the threshold, is the reflection time of the leakage point (15), is the initial reflection time, is the end reflection time, is the length of the leakage detection sensor element (4).

3. The farmland irrigation pipeline leakage detection system based on microwave impedance according to claim 1 is characterized in that: When the leakage point (15) is continuously leaking or the leakage area is larger than the sheet-like area formed by the threshold, the leakage degree is determined according to the following formula: in, is the leakage degree when the leakage point (15) is continuously leaking or the leakage area is larger than the sheet-like area formed by the threshold, that is, the length of the leakage detection sensor element (4) passing through the sheet-like area, is the reflection time of the leakage detection sensor element (4) entering the leakage point (15), is the reflection time of the leakage detection sensor element (4) leaving the leakage point (15), is the initial reflection time, is the end reflection time, is the length of the leakage detection sensor element (4).

4. The farmland irrigation pipeline leakage detection system based on microwave impedance according to claim 1 is characterized in that: The axial position is determined according to the following formula: in, Y is the axial position, A is the thread pitch, l is the length of the leakage detection sensor element (4) wound around the buried pipeline (9) once, is the leakage position or the leakage extent.

5. The farmland irrigation pipeline leakage detection system based on microwave impedance according to claim 1 is characterized in that: The radial position is determined according to the following formula: in, is the radial position, % is the modulo symbol, l The length of the leakage detection sensor element (4) wound around the buried pipeline (9) once.

6. The farmland irrigation pipeline leakage detection system based on microwave impedance according to claim 1 is characterized in that: It also comprises a bracket (10) and an equipment box (11), wherein the bracket (10) is fixed in a base (12), the equipment box (11) is arranged on the bracket (10), and the microwave impedance measurement circuit (3), the coaxial multiplexer (5), the data collector (6) and the wireless data transmission module (7) are all arranged in the equipment box (11).

7. The farmland irrigation pipeline leakage detection system based on microwave impedance according to claim 6 is characterized in that: It also comprises a solar panel (1) and a lead-acid battery (2), wherein the solar panel (1) is arranged on the bracket (10), and the lead-acid battery (2) is arranged in the equipment box (11); the solar panel (1) charges the lead-acid battery (2), and the lead-acid battery (2) supplies power to the microwave impedance measurement circuit (3), the data collector (6), and the wireless data transmission module (7).

8. The farmland irrigation pipeline leakage detection system based on microwave impedance according to claim 1 is characterized in that: The leakage detection sensor element (4) comprises a first parallel double-wire conductor (16) and a second parallel double-wire conductor (17), wherein the first parallel double-wire conductor (16) and the second parallel double-wire conductor (17) are both coated with a parallel double-wire insulator (18) on the outside. The coaxial multiplexer (5) is electrically connected to the leakage detection sensor element (4) via a coaxial cable (14); the coaxial cable (14) comprises a coaxially arranged coaxial central conductor (19) and a coaxial shielding layer (20); the coaxial central conductor (19) and the coaxial shielding layer (20) have an insulating medium (21); the coaxial shielding layer (20) is coated with a polyvinyl chloride sheath (22); The first parallel dual-wire conductor (16) and the second parallel dual-wire conductor (17) are electrically connected to the coaxial line center conductor (19) and the coaxial line shielding layer (20), respectively.

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