Soil spark discharge critical breakdown field intensity measuring device, system and method

Abstract

The invention relates to a soil spark discharge critical breakdown field intensity measuring device, system and method, a soil test cylinder encloses a rotating cavity, to-be-measured soil is placed in the rotating cavity, a first metal circular plate electrode covers the top of the to-be-measured soil, and a second metal circular plate electrode is located at the bottom of the rotating cavity; the first metal circular plate electrode can move relative to the soil test cylinder; the measuring device and the impulse current generator form a closed loop, the voltage divider and the current transformer are both arranged on the closed loop, and the voltage divider and the current transformer are both connected with the data collector; the measuring method comprises the following steps: adding to-be-measured soil, connecting the measuring system, applying impact current, and calculating critical breakdown field strength. A uniform electric field environment is constructed in the soil by utilizing the symmetry of the soil test cylinder, so that the fringe effect and the end effect can be effectively avoided, the relatively accurate soil spark discharge critical breakdown field strength can be obtained, and a basis is provided for the impact characteristic simulation calculation of the grounding device.

Description

Technical Field

[0001] The present invention relates to the field of high voltage technology, and in particular to a device, system and method for measuring the critical breakdown field strength of soil spark discharge. Background Art

[0002] Currently, when transmission lines and towers are struck by lightning, the lightning current flows through the tower or through a lightning arrester, dissipating from the grounding device into the earth. The grounding device, under the influence of the surge current, generates a transient electromagnetic field around it, forming a certain electric field strength in the soil. As the surge current amplitude increases, the electric field strength in the soil continues to increase. If the electric field strength in the soil near the grounding conductor exceeds the critical breakdown field strength of the soil, spark discharges will occur in the soil near the grounding conductor, causing the soil to break down. The resistivity of the soil in the spark discharge area is greatly reduced, thus significantly reducing the voltage drop near the grounding conductor. Therefore, it is very necessary to study the surge discharge characteristics of the soil around the grounding device.

[0003] Numerous studies have confirmed that large surge currents in grounding systems can cause ionization of the soil surrounding the grounding element, generating spark discharges, resulting in a typical nonlinear surge response. To calculate the impact of soil ionization on the surge performance of grounding systems, soil spark discharge modeling is often required during simulation analysis and safety performance assessment of tower grounding systems. The key parameter in establishing this model is determining the critical breakdown field strength of the soil.

[0004] The nonlinear ionization of soil under high current surges is dependent on numerous electrical and geometric parameters, making its development difficult to predict. The breakdown field strength of soil depends on soil type and moisture content, and the ionization gradient varies significantly between soil types. The complexity of soil structure and the diversity of soil types make studying soil ionization and breakdown mechanisms an extremely challenging task.

[0005] At present, there is no unified conclusion on the critical breakdown field strength of various soils. Therefore, there is an urgent need for a measuring device for measuring the soil spark discharge breakdown field strength to obtain the critical breakdown field strength of different types of soils. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a device, system and method for measuring the critical breakdown field strength of soil spark discharge. The advantage of the present invention is that it can obtain relatively accurate critical breakdown field strength of soil spark discharge, providing a basis for the simulation calculation of the impact characteristics of the grounding device.

[0007] The above-mentioned object of the present invention is achieved through the following technical solutions: On the one hand, the present invention provides a device for measuring the critical breakdown field strength of soil spark discharge, comprising a soil test cylinder, a first metal circular plate electrode, and a second metal circular plate electrode; the soil test cylinder is arranged to form a rotating cavity, the first metal circular plate electrode and the second metal circular plate electrode are both placed in the rotating cavity, the first metal circular plate electrode and the second metal circular plate electrode are spaced apart along the center line direction of the rotating cavity, the soil to be measured is placed in the rotating cavity, the soil to be measured is located between the first metal circular plate electrode and the second metal circular plate electrode, the first metal circular plate electrode cover is arranged on the top of the soil to be measured, and the second metal circular plate electrode is located at the bottom of the rotating cavity, the first metal circular plate electrode can move relative to the soil test cylinder to adjust the distance between the first metal circular plate electrode and the second metal circular plate electrode; the first metal circular plate electrode and the second metal circular plate electrode are both connected to an impulse current generator, and the impulse current generator is used to apply an impulse current between the first metal circular plate electrode and the second metal circular plate electrode of the soil to be measured.

[0008] Preferably, in the device for measuring the critical breakdown field strength of soil spark discharge provided by the present invention, the soil test cylinder includes a cylinder body and an insulating support frame, the insulating support frame is arranged to form an installation cavity, and the cylinder body is inserted into the installation cavity.

[0009] Preferably, the device for measuring the critical breakdown field strength of soil spark discharge provided by the present invention, the insulating support frame includes a first epoxy ring, a second epoxy ring, a third epoxy ring and a plurality of epoxy rods, the first epoxy ring is sleeved on the top end of the cylinder, the second epoxy ring is sleeved on the bottom end of the cylinder, the third epoxy ring is located on the side of the second epoxy ring away from the first epoxy ring, the second epoxy ring and the third epoxy ring are spaced a preset distance apart, the top ends of the plurality of epoxy rods are all connected to the first epoxy ring, the bottom ends of the plurality of epoxy rods are all connected to the third epoxy ring through the second epoxy ring, and the plurality of epoxy rods are arranged at circumferential intervals around the epoxy ring.

[0010] Preferably, in the device for measuring the critical breakdown field strength of soil spark discharge provided by the present invention, the cylinder is made of organic glass.

[0011] Preferably, in the device for measuring the critical breakdown field strength of soil spark discharge provided by the present invention, a first cantilever is provided on the first metal circular plate electrode, and one end of the first cantilever away from the first metal circular plate electrode extends to the outside of the rotating cavity along the center line direction of the rotating cavity.

[0012] Preferably, in the device for measuring the critical breakdown field strength of soil spark discharge provided by the present invention, the first cantilever includes a first metal screw and a first metal nut, the bottom end of the first metal screw sequentially passes through the first metal nut and the top cover of the soil test cylinder and is inserted into the rotating cavity, and is connected to the first metal circular plate electrode; the first metal screw is threadedly connected to the first metal nut, and the first metal screw can move relative to the soil test cylinder; the first metal screw moves along the center line direction of the rotating cavity, and when the first metal screw moves and drives the first metal circular plate electrode to a preset position, the first metal nut is rotated until the bottom end of the first metal nut abuts against the top surface of the top cover of the soil test cylinder, so that the first metal screw is locked; the first metal nut is a current injection end, and the first metal nut is used to connect to the impulse current generator.

[0013] Preferably, in the device for measuring the critical breakdown field strength of soil spark discharge provided by the present invention, a second cantilever is provided on the second metal circular plate electrode, and one end of the second cantilever away from the second metal circular plate electrode extends to the outside of the rotating cavity along the center line direction of the rotating cavity.

[0014] Preferably, in the device for measuring the critical breakdown field strength of soil spark discharge provided by the present invention, the second cantilever includes a second metal screw and a second metal nut, the top end of the second metal screw sequentially passes through the second metal nut and the bottom cover of the soil test cylinder and is inserted into the rotating cavity, and is connected to the bottom surface of the second metal circular plate electrode, the second metal screw is threadedly connected to the second metal nut, and the top surface of the second metal nut is pressed against the bottom surface of the bottom cover of the soil test cylinder to lock the second metal screw; the second metal nut is a current return end, and the second metal nut is used to connect to the impulse current generator.

[0015] On the other hand, the present invention provides a measurement system for the critical breakdown field strength of soil spark discharge, comprising the above-mentioned measurement device for the critical breakdown field strength of soil spark discharge, a voltage divider, a current transformer and a data collector; the first metal circular plate electrode is connected to the output end of the impulse current generator, the second metal circular plate electrode is connected to the input end of the impulse current generator, the measuring device and the impulse current generator form a closed loop, the voltage divider and the current transformer are both arranged on the closed loop, the voltage divider is connected in parallel to the measuring device, the current transformer is connected in series to the measuring device, and the voltage divider and the current transformer are both connected to the data collector; the voltage divider is used to measure the voltage of the soil to be measured; the current transformer is used to measure the current of the closed loop.

[0016] On the other hand, the present invention provides a measurement method using the above-mentioned soil spark discharge critical breakdown field strength measurement system, comprising the following steps:

[0017] Placing the first metal circular plate electrode at the bottom of the rotating cavity formed by the soil test cylinder, placing the soil to be measured in the rotating cavity, and covering the top of the soil to be measured with the second metal circular plate electrode;

[0018] The first metal circular plate electrode is connected to the output end of the impulse current generator, the second metal circular plate electrode is connected to the input end of the impulse current generator, the measuring device and the impulse current generator form a closed loop, the voltage divider and the current transformer are both arranged on the closed loop, the voltage divider is connected in parallel to the measuring device, the current transformer is connected in series to the measuring device, and the voltage divider and the current transformer are both connected to the data collector;

[0019] applying impulse currents of different amplitudes to the soil to be measured in ascending order, and measuring the current and voltage at both ends of the soil to be measured, wherein a preset time interval is left between each two tests, and when the measured current and voltage waveforms jump, the soil to be measured is broken down;

[0020] Statistical analysis is performed through multiple tests. When the soil to be measured is broken down, the inter-electrode distance and the peak breakdown voltage at that time are recorded, and the critical breakdown field strength of the soil to be measured is calculated as the peak breakdown voltage / inter-electrode distance.

[0021] In summary, the beneficial technical effects of the present invention are as follows: the device, system and method for measuring the critical breakdown field strength of soil spark discharge provided by the present application, wherein the measuring device includes a soil test cylinder, a first metal circular plate electrode and a second metal circular plate electrode; the soil test cylinder is arranged to form a rotating cavity, the first metal circular plate electrode and the second metal circular plate electrode are both placed in the rotating cavity, the first metal circular plate electrode and the second metal circular plate electrode are spaced apart along the center line direction of the rotating cavity, the soil to be measured is placed in the rotating cavity, the soil to be measured is located between the first metal circular plate electrode and the second metal circular plate electrode, the first metal circular plate electrode cover is arranged on the top of the soil to be measured, and the second metal circular plate electrode is located at the bottom of the rotating cavity, the first metal circular plate electrode can move relative to the soil test cylinder to adjust the distance between the first metal circular plate electrode and the second metal circular plate electrode; the first metal circular plate electrode and the second metal circular plate electrode are both The impulse current generator is connected, and the impulse current generator is used to apply an impulse current between the first metal circular plate electrode and the second metal circular plate electrode of the soil to be measured; the measurement system includes a measuring device, a voltage divider, a current transformer and a data collector, the measuring device and the impulse current generator form a closed loop, the voltage divider and the current transformer are both arranged on the closed loop, the voltage divider is connected in parallel with the measuring device, the current transformer is connected in series with the measuring device, and the voltage divider and the current transformer are both connected to the data collector; the measurement method process is: adding the soil to be measured - connecting the measurement system - applying the impulse current - calculating the critical breakdown field strength of the soil to be measured; such a setting utilizes the symmetry of the soil test cylinder to construct a uniform electric field environment in the soil, which can effectively avoid edge effects and end effects, and can obtain a relatively accurate critical breakdown field strength of soil spark discharge, providing a basis for the simulation calculation of the impulse characteristics of the grounding device. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the device for measuring the critical breakdown field strength of soil spark discharge provided by the first embodiment of the present invention.

[0023] Figure 2 It is a structural schematic diagram of a soil test cylinder in a device for measuring critical breakdown field strength of soil spark discharge provided by a first embodiment of the present invention.

[0024] Figure 3 It is a structural diagram of a measurement system for critical breakdown field strength of soil spark discharge provided by the first embodiment of the present invention.

[0025] Figure 4 This is a flow chart of a method for measuring the critical breakdown field strength of soil spark discharge provided by the second embodiment of the present invention.

[0026] Figure 5aThese are the soil voltage curve and current curve under impulse current (without any discharge phenomenon) in the method for measuring the critical breakdown field strength of soil spark discharge provided by the second embodiment of the present invention.

[0027] Figure 5b These are the soil voltage curve and current curve under impulse current in the method for measuring the critical breakdown field strength of soil spark discharge provided by the second embodiment of the present invention (local spark discharge occurs near the electrode).

[0028] Figure 5c These are the soil voltage curve and current curve under impulse current (discharge penetration occurs between electrodes) in the method for measuring the critical breakdown field strength of soil spark discharge provided by the second embodiment of the present invention.

[0029] In the figure, 1. measurement system; 10. measuring device; 11. soil test cylinder; 111. cylinder; 1111. rotating cavity; 112. insulating support frame; 1121. first epoxy ring; 1122. second epoxy ring; 1123. third epoxy ring; 1124. epoxy rod; 12. first metal circular plate electrode; 121. first cantilever; 1211. first metal screw; 1212. first metal nut; 13. second metal circular plate electrode; 131. second cantilever; 1311. second metal screw; 1312. second metal nut; 20. voltage divider; 30. current transformer; 40. data collector; 50. impulse current generator; 2. soil to be measured. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below with reference to the accompanying drawings.

[0031] First embodiment:

[0032] Reference Figure 1 and Figure 2, a soil spark discharge critical breakdown field strength measurement system 1 disclosed in the first embodiment of the present invention includes a soil spark discharge critical breakdown field strength measurement device 10, a voltage divider 20, a current transformer 30 and a data collector 40; wherein, the soil spark discharge critical breakdown field strength measurement device 10 includes a soil test cylinder 11, a first metal circular plate electrode 12 and a second metal circular plate electrode 13; the soil test cylinder 11 is surrounded by a rotating cavity 1111, the first metal circular plate electrode 12 and the second metal circular plate electrode 13 are both placed in the rotating cavity 1111, and the first metal circular plate electrode 12 and the second metal circular plate electrode 13 are spaced apart along the center line direction of the rotating cavity 1111, and the soil 2 to be measured is placed in the rotating cavity 1111, and the soil 2 to be measured is located between the first metal circular plate electrode 12 and the second metal circular plate electrode 13 The first metal circular plate electrode 12 is covered on the top of the soil 2 to be measured, and the second metal circular plate electrode 13 is located at the bottom of the rotating cavity 1111. The first metal circular plate electrode 12 can move relative to the soil test cylinder 11 to adjust the distance between the first metal circular plate electrode 12 and the second metal circular plate electrode 13; the first metal circular plate electrode 12 and the second metal circular plate electrode 13 are both connected to the impulse current generator 50, and the impulse current generator 50 is used to apply an impulse current between the first metal circular plate electrode 12 and the second metal circular plate electrode 13 to the soil 2 to be measured; with this arrangement, a uniform electric field environment is constructed in the soil by utilizing the symmetry of the soil test cylinder 11, which can effectively avoid edge effects and end effects, and can obtain a relatively accurate critical breakdown field strength of soil spark discharge, providing a basis for the simulation calculation of the impulse characteristics of the grounding device.

[0033] It should be noted that the soil 2 to be measured is placed in the rotating cavity 1111 and is manually pressed and compacted uniformly so that the density of the soil 2 to be measured is consistent with that of the original soil.

[0034] The diameters of the first metal circular plate electrode 12 and the second metal circular plate electrode 13 are both consistent with the diameter of the rotating cavity 1111 .

[0035] Specifically, the surfaces of the first metal circular plate electrode 12 and the second metal circular plate electrode 13 should be polished to be smooth so as to reduce irregularities on the electrodes and prevent these irregularities from strengthening the local electric field.

[0036] Continue to refer to Figure 3In this embodiment, the first metal circular plate electrode 12 is connected to the output end of the impulse current generator 50, the second metal circular plate electrode 13 is connected to the input end of the impulse current generator 50, the measuring device 10 and the impulse current generator 50 form a closed loop, the voltage divider 20 and the current transformer 30 are both arranged on the closed loop, the voltage divider 20 is connected in parallel with the measuring device 10, the current transformer 30 is connected in series with the measuring device 10, and the voltage divider 20 and the current transformer 30 are both connected to the data collector 40; the voltage divider 20 is used to measure the voltage of the soil 2 to be measured; the current transformer 30 is used to measure the current of the closed loop.

[0037] During use, impulse currents of varying amplitudes, 8 / 20μs, are applied to the soil sample (2) in ascending order. The current and voltage across the soil are measured. To ensure that any static charge in the soil is discharged, a five-minute interval is maintained between tests. When the measured current and voltage waveforms change, i.e., a significant increase in the closed-loop current and a significant decrease in the voltage drop across the soil, the soil has broken down. Statistical analysis is performed through multiple tests. If the soil breaks down under the same test conditions, the inter-electrode distance and peak breakdown voltage (i.e., peak voltage before breakdown) are recorded. The critical breakdown field strength of the soil can be calculated as: peak breakdown voltage / inter-electrode distance.

[0038] Furthermore, in this embodiment, the soil test cylinder 11 includes a cylinder 111 and an insulating support frame 112. The insulating support frame 112 is arranged to form an installation cavity, and the cylinder 111 is inserted into the installation cavity. By setting the insulating support frame 112, the insulating support frame 112 is used to support and reinforce the cylinder 111.

[0039] The cylinder 111 is formed into a rotating cavity 1111 , and the first metal circular plate electrode 12 and the second metal circular plate electrode 13 are both placed in the rotating cavity 1111 formed by the cylinder 111 .

[0040] Exemplarily, the barrel 111 can be made of organic glass. Of course, the barrel 111 can also be made of plastic.

[0041] Furthermore, in this embodiment, the insulating support frame 112 includes a first epoxy ring 1121, a second epoxy ring 1122, a third epoxy ring 1123 and a plurality of epoxy rods 1124. The first epoxy ring 1121 is sleeved on the top end of the cylinder 111, the second epoxy ring 1122 is sleeved on the bottom end of the cylinder 111, and the third epoxy ring 1123 is located on the side of the second epoxy ring 1122 away from the first epoxy ring 1121. The second epoxy ring 1122 and the third epoxy ring 1123 are spaced a preset distance apart. The top ends of the plurality of epoxy rods 1124 are all connected to the first epoxy ring 1121, and the bottom ends of the plurality of epoxy rods 1124 are all connected to the third epoxy ring 1123 through the second epoxy ring 1122, and the plurality of epoxy rods 1124 are arranged at intervals around the circumference of the epoxy ring.

[0042] Specifically, the center line of the first epoxy ring 1121, the center line of the second epoxy ring 1122, and the center line of the third epoxy ring 1123 are all arranged parallel to the center line of the cylinder 111. In some feasible embodiments, the center line of the first epoxy ring 1121, the center line of the second epoxy ring 1122, and the center line of the third epoxy ring 1123 are all arranged collinearly with the center line of the cylinder 111.

[0043] In this embodiment, the number of epoxy rods 1124 is 6. Of course, the number of epoxy rods 1124 can also be 8 or 9.

[0044] Furthermore, in this embodiment, a first cantilever 121 is provided on the first metal circular plate electrode 12 , and one end of the first cantilever 121 away from the first metal circular plate electrode 12 extends along the center line of the rotating cavity 1111 to the outside of the rotating cavity 1111 .

[0045] The first cantilever 121 includes a first metal screw 1211 and a first metal nut 1212. The bottom end of the first metal screw 1211 passes through the first metal nut 1212 and the top cover of the soil test cylinder 11 in sequence and is inserted into the rotating cavity 1111 and connected to the first metal circular plate electrode 12. The first metal screw 1211 is threadedly connected to the first metal nut 1212, and the first metal screw 1211 can move relative to the soil test cylinder 11. The first metal screw 1211 moves along the center line direction of the rotating cavity 1111. When the first metal screw 1211 moves and drives the first metal circular plate electrode 12 to move to a preset position, the first metal nut 1212 is rotated until the bottom end of the first metal nut 1212 abuts against the top surface of the top cover of the soil test cylinder 11, so that the first metal screw 1211 is locked; the first metal nut 1212 is the current injection end, and the first metal nut 1212 is used to connect with the impulse current generator 50; by setting the first monitoring nut, the first metal nut 1212 plays a limiting role on the first metal screw 1211.

[0046] Specifically, the bottom end of the first metal screw 1211 passes through the first metal nut 1212 and the top cover of the cylinder 111 in sequence and is inserted into the rotating cavity 1111, and is connected to the first metal circular plate electrode 12. The center line of the first metal screw 1211 is set parallel to the center line of the cylinder 111. In some feasible methods, the center line of the first metal screw 1211 is set collinearly with the center line of the cylinder 111.

[0047] Furthermore, in this embodiment, a second cantilever 131 is provided on the second metal circular plate electrode 13 , and one end of the second cantilever 131 away from the second metal circular plate electrode 13 extends along the center line of the rotating cavity 1111 to the outside of the rotating cavity 1111 .

[0048] Among them, the second cantilever 131 includes a second metal screw 1311 and a second metal nut 1312. The top end of the second metal screw 1311 passes through the second metal nut 1312 and the bottom cover of the soil test cylinder 11 in sequence and is inserted into the rotating cavity 1111, and is connected to the bottom surface of the second metal circular plate electrode 13. The second metal screw 1311 is threadedly connected to the second metal nut 1312, and the top surface of the second metal nut 1312 is pressed against the bottom surface of the bottom cover of the soil test cylinder 11 to lock the second metal screw 1311; the second metal nut 1312 is the current return end, and the second metal nut 1312 is used to connect to the impulse current generator 50.

[0049] Specifically, the top end of the second metal screw 1311 passes through the second metal nut 1312 and the bottom cover of the cylinder 111 in sequence and is inserted into the rotating cavity 1111, and is connected to the bottom surface of the second metal circular plate electrode 13. The center line of the second metal screw 1311 is set parallel to the center line of the cylinder 111. In some feasible methods, the center line of the second metal screw 1311 is set collinearly with the center line of the cylinder 111.

[0050] Second embodiment:

[0051] Continue to refer to Figure 4 The second embodiment of the present invention provides a measurement method for the soil spark discharge critical breakdown field strength using the measurement system 1 of the first embodiment, comprising the following steps:

[0052] S101. Place the first metal circular plate electrode 12 at the bottom of the rotating cavity 1111 enclosed by the soil test cylinder 11, place the soil 2 to be measured in the rotating cavity 1111, and cover the top of the soil 2 to be measured with the second metal circular plate electrode 13.

[0053] Specifically, the soil 2 to be measured is placed in the rotating cavity 1111 and manually pressed and compacted evenly to ensure that the soil 2 to be measured maintains the same density as the original soil. The second metal disc electrode 13 is placed on the top of the soil 2 to ensure uniform and good contact between the soil 2 to be measured and the first and second metal disc electrodes 12, 13. The first metal screw 1211 is moved along the centerline of the rotating cavity 1111. The movement of the first metal screw 1211 drives the first metal disc electrode 12 to adjust the distance between the first and second metal disc electrodes 12, 13. When the first metal disc electrode 12 moves to a preset position, the first metal nut 1212 is rotated until the bottom end of the first metal nut 1212 abuts the top surface of the top cover of the soil testing cylinder 11, thereby locking the first metal screw 1211.

[0054] S102, the first metal circular plate electrode 12 is connected to the output end of the impulse current generator 50, the second metal circular plate electrode 13 is connected to the input end of the impulse current generator 50, the measuring device 10 and the impulse current generator 50 form a closed loop, the voltage divider 20 and the current transformer 30 are both arranged on the closed loop, the voltage divider 20 is connected to the measuring device 10 in parallel, the current transformer 30 is connected to the measuring device 10 in series, and the voltage divider 20 and the current transformer 30 are both connected to the data collector 40.

[0055] Specifically, the first metal nut 1212 is a current injection end, the second metal nut 1312 is a current return end, the first metal nut 1212 is connected to the output end of the impulse current generator 50, and the second metal nut 1312 is connected to the input end of the impulse current generator 50.

[0056] S103. Apply impulse currents of different amplitudes to the soil 2 to be measured in sequence from small to large, and measure the current and voltage at both ends of the soil 2 to be measured, wherein a preset time interval is set between each two tests. When the measured current and voltage waveforms jump, the soil 2 to be measured is broken down.

[0057] Specifically, impulse currents of 8 / 20μs with different amplitudes are applied to the soil samples in order from small to large, and the current and voltage at both ends of the soil 2 to be measured are measured. To ensure that any static charge in the soil 2 to be measured is released, a 5-minute interval is maintained between each test. When the measured current and voltage waveforms jump, that is, the closed-loop current has a significant increase and the voltage drop of the soil 2 to be measured has a significant decrease, it means that the soil 2 to be measured has been broken down. Typical soil voltage curves and current curves under impulse current are shown in the figure below. Figure 5a-5c As shown. Among them, Figure 5cFigure 2 shows the voltage and current waveforms when the soil 2 to be measured is broken down. At 70 μs, the voltage drop on the soil 2 to be measured suddenly drops, while the closed loop current rises sharply. This is the moment when the soil 2 to be measured is broken down.

[0058] S104. Statistical analysis is performed through multiple tests. When the soil 2 to be measured is broken down, the inter-electrode distance and the peak breakdown voltage at that time are recorded, and the critical breakdown field strength of the soil 2 to be measured is calculated as follows: peak breakdown voltage / inter-electrode distance.

[0059] Specifically, through statistical analysis of multiple tests, if under the same test conditions, the soil 2 to be measured has a probability of being broken down by about 50%, then the maximum value of the voltage wave between the first metal circular plate electrode 12 and the second metal circular plate electrode 13 at this time is the 50% impulse discharge voltage U under the voltage waveform. 50 By recording the inter-electrode distance and the breakdown voltage peak value (i.e., the voltage peak value before breakdown), the critical breakdown field strength of the soil 2 to be measured can be calculated as follows: breakdown voltage peak value / inter-electrode distance.

[0060] The present application provides a device 10, system and method for measuring the critical breakdown field strength of soil spark discharge, wherein the measuring device 10 includes a soil test cylinder 11, a first metal circular plate electrode 12 and a second metal circular plate electrode 13; the soil test cylinder 11 is arranged to form a rotating cavity 1111, the first metal circular plate electrode 12 and the second metal circular plate electrode 13 are both placed in the rotating cavity 1111, and the first metal circular plate electrode 12 and the second metal circular plate electrode 13 are spaced apart along the center line direction of the rotating cavity 1111, and the measured The soil 2 is placed in the rotating cavity 1111. The soil 2 to be measured is located between the first metal circular plate electrode 12 and the second metal circular plate electrode 13. The first metal circular plate electrode 12 is covered on the top of the soil 2 to be measured, and the second metal circular plate electrode 13 is located at the bottom of the rotating cavity 1111. The first metal circular plate electrode 12 can move relative to the soil test cylinder 11 to adjust the distance between the first metal circular plate electrode 12 and the second metal circular plate electrode 13. The first metal circular plate electrode 12 and the second metal circular plate electrode 13 are both The impulse current generator 50 is connected, and the impulse current generator 50 is used to apply an impulse current between the first metal circular plate electrode 12 and the second metal circular plate electrode 13 of the soil 2 to be measured. The measurement system 1 includes a measuring device 10, a voltage divider 20, a current transformer 30 and a data collector 40. The measuring device 10 and the impulse current generator 50 form a closed loop. The voltage divider 20 and the current transformer 30 are both arranged on the closed loop. The voltage divider 20 is connected in parallel with the measuring device 10, and the current transformer 30 is connected in series with the measuring device 10. The voltage divider 20 and the current transformer 30 are both connected to the data collector 40. The process of the measurement method is: adding the soil 2 to be measured - connecting the measurement system 1 - applying an impulse current - calculating the critical breakdown field strength of the soil 2 to be measured; such a setting utilizes the symmetry of the soil test cylinder 11 to construct a uniform electric field environment in the soil, which can effectively avoid edge effects and end effects, and can obtain a relatively accurate critical breakdown field strength of soil spark discharge, providing a basis for the simulation calculation of the impulse characteristics of the grounding device.

[0061] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

[0062] Finally, it should be noted that the above embodiments are merely examples for the purpose of illustrating the present invention and are not intended to limit the embodiments. Those skilled in the art will readily appreciate that other variations or modifications based on the above description are possible. It is not necessary and impossible to provide an exhaustive list of all embodiments. However, obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A device for measuring the critical breakdown field strength of soil spark discharge, characterized in that: It includes a soil test cylinder, a first metal circular plate electrode and a second metal circular plate electrode; The soil testing cylinder is configured to form a rotating cavity, the first metal circular plate electrode and the second metal circular plate electrode are both placed in the rotating cavity, the first metal circular plate electrode and the second metal circular plate electrode are spaced apart along the centerline direction of the rotating cavity, the soil to be measured is placed in the rotating cavity, the soil to be measured is located between the first metal circular plate electrode and the second metal circular plate electrode, the first metal circular plate electrode cover is provided on the top of the soil to be measured, the second metal circular plate electrode is located at the bottom of the rotating cavity, and the first metal circular plate electrode can move relative to the soil testing cylinder to adjust the distance between the first metal circular plate electrode and the second metal circular plate electrode; The first metal circular plate electrode and the second metal circular plate electrode are both connected to a surge current generator, and the surge current generator is used to apply a surge current between the first metal circular plate electrode and the second metal circular plate electrode of the soil to be measured.

2. The device for measuring the critical breakdown field strength of soil spark discharge according to claim 1, characterized in that: The soil testing cylinder comprises a cylinder body and an insulating support frame. The insulating support frame is arranged to form an installation cavity, and the cylinder body is inserted into the installation cavity.

3. The device for measuring the critical breakdown field strength of soil spark discharge according to claim 2, characterized in that: The insulating support frame includes a first epoxy ring, a second epoxy ring, a third epoxy ring and a plurality of epoxy rods. The first epoxy ring is sleeved on the top end of the cylinder, the second epoxy ring is sleeved on the bottom end of the cylinder, the third epoxy ring is located on the side of the second epoxy ring away from the first epoxy ring, and the second epoxy ring and the third epoxy ring are spaced a preset distance apart. The top ends of the plurality of epoxy rods are all connected to the first epoxy ring, and the bottom ends of the plurality of epoxy rods are all connected to the third epoxy ring through the second epoxy ring. The plurality of epoxy rods are arranged at intervals around the circumference of the epoxy ring.

4. The device for measuring the critical breakdown field strength of soil spark discharge according to any one of claims 2-3, characterized in that: The cylinder is made of organic glass.

5. The device for measuring the critical breakdown field strength of soil spark discharge according to claim 1, characterized in that: A first cantilever is provided on the first metal circular plate electrode, and one end of the first cantilever away from the first metal circular plate electrode extends to the outside of the rotating cavity along the center line direction of the rotating cavity.

6. The device for measuring the critical breakdown field strength of soil spark discharge according to claim 5, characterized in that: The first cantilever includes a first metal screw and a first metal nut. The bottom end of the first metal screw passes through the first metal nut and the top cover of the soil testing cylinder in sequence and is inserted into the rotating cavity and connected to the first metal circular plate electrode. The first metal screw is threadedly connected to the first metal nut, and the first metal screw is movable relative to the soil testing cylinder; The first metal screw moves along the center line of the rotating cavity. When the first metal screw drives the first metal circular plate electrode to a preset position, the first metal nut is rotated until the bottom end of the first metal nut abuts against the top surface of the top cover of the soil testing cylinder, thereby locking the first metal screw. The first metal nut is a current injection end, and the first metal nut is used to be connected to the impulse current generator.

7. The device for measuring the critical breakdown field strength of soil spark discharge according to claim 1, characterized in that: A second cantilever is provided on the second metal circular plate electrode, and one end of the second cantilever away from the second metal circular plate electrode extends to the outside of the rotating cavity along the center line direction of the rotating cavity.

8. The device for measuring the critical breakdown field strength of soil spark discharge according to claim 7, characterized in that: The second cantilever includes a second metal screw and a second metal nut. The top end of the second metal screw passes through the second metal nut and the bottom cover of the soil testing cylinder in sequence and is inserted into the rotating cavity and connected to the bottom surface of the second metal circular plate electrode. The second metal screw is threadedly connected to the second metal nut. The top surface of the second metal nut abuts against the bottom surface of the bottom cover of the soil testing cylinder to lock the second metal screw. The second metal nut is a current return end, and the second metal nut is used to be connected to the impulse current generator.

9. A measurement system for critical breakdown field strength of soil spark discharge, characterized by: A device for measuring the critical breakdown field strength of soil spark discharge according to any one of claims 1 to 8, a voltage divider, a current transformer and a data collector; The first metal circular plate electrode is connected to the output end of the impulse current generator, the second metal circular plate electrode is connected to the input end of the impulse current generator, the measuring device and the impulse current generator form a closed loop, the voltage divider and the current transformer are both arranged on the closed loop, the voltage divider is connected in parallel to the measuring device, the current transformer is connected in series to the measuring device, and the voltage divider and the current transformer are both connected to the data collector; The voltage divider is used to measure the voltage of the soil to be measured; The current transformer is used to measure the current of the closed loop.

10. A measurement method using the soil spark discharge critical breakdown field strength measurement system according to claim 9, characterized in that: The steps include: Placing the first metal circular plate electrode at the bottom of the rotating cavity formed by the soil test cylinder, placing the soil to be measured in the rotating cavity, and covering the top of the soil to be measured with the second metal circular plate electrode; The first metal circular plate electrode is connected to the output end of the impulse current generator, the second metal circular plate electrode is connected to the input end of the impulse current generator, the measuring device and the impulse current generator form a closed loop, the voltage divider and the current transformer are both arranged on the closed loop, the voltage divider is connected in parallel to the measuring device, the current transformer is connected in series to the measuring device, and the voltage divider and the current transformer are both connected to the data collector; applying impulse currents of different amplitudes to the soil to be measured in order from small to large, and measuring the current and voltage at both ends of the soil to be measured, wherein a preset time interval is left between each two tests, and when the measured current and voltage waveforms jump, the soil to be measured is broken down; Statistical analysis is performed through multiple tests. When the soil to be measured is broken down, the inter-electrode distance and the peak breakdown voltage at that time are recorded, and the critical breakdown field strength of the soil to be measured is calculated as the peak breakdown voltage / inter-electrode distance.

Images