CN113311297A - Method for observing three-dimensional discharge morphology of soil around grounding device - Google Patents
Method for observing three-dimensional discharge morphology of soil around grounding device Download PDFInfo
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- CN113311297A CN113311297A CN202110545988.XA CN202110545988A CN113311297A CN 113311297 A CN113311297 A CN 113311297A CN 202110545988 A CN202110545988 A CN 202110545988A CN 113311297 A CN113311297 A CN 113311297A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1218—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing using optical methods; using charged particle, e.g. electron, beams or X-rays
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
- G01R31/1263—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
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Abstract
The invention discloses a method for observing three-dimensional discharge morphology of soil around a grounding device, and belongs to the technical field of high voltage. The method comprises the following steps: in a darkroom, placing a plurality of layers of x films with holes punched in the middle in a metal cylinder, penetrating a grounding rod through the axis position of the x film metal cylinder, and filling soil in the metal cylinder; taking out the metal cylinder from the darkroom, placing the metal cylinder in a preset range near the lightning impulse generator, and carrying out an impulse current/voltage test on the metal cylinder; acquiring a soil discharge photo; and determining the three-dimensional discharge morphology of the soil around the grounding device according to the acquired impact current waveform on the grounding rod, the potential difference waveform between the grounding rod and the metal cylinder and the acquired soil discharge photo. The invention can observe the discharge appearance of soil in all directions.
Description
Technical Field
The invention relates to the technical field of high voltage, in particular to a method for observing three-dimensional discharge morphology of soil around a grounding device.
Background
China suffers frequent lightning stroke every year and has great harm. Good grounding is a key measure for lightning protection. Lightning protection equipment such as lightning rods, lightning wires and lightning arresters are required to be provided with corresponding grounding devices so as to lead lightning current to the ground for discharging. Because the lightning current is very large, when the lightning current is concentrated and scattered to flow into the ground through the grounding device, a very high potential gradient is generated in the soil, and when the lightning current exceeds the tolerance field intensity of the soil, a discharge phenomenon can occur in the soil. The discharge of the soil will greatly affect the lightning impulse characteristics of the grounding device, resulting in non-linear changes in the impulse grounding resistance over time, and further affect the lightning protection characteristics of the lightning rod, the lightning conductor and the lightning arrester. Therefore, it is necessary to study the characteristics of the soil around the grounding device.
The current discharge research aiming at the soil has the following problems:
1. the method mainly researches the discharge characteristics of the soil under power frequency, and lacks the research on the discharge characteristics of the soil under the lightning stroke impact transient state;
2. the discharge gap is mainly in the form of a point-plate, point-point, ball-ball, whereas in practice the grounding body is usually composed of a rod-shaped grounding device connection assembly, and thus lacks the discharge characteristic of a wire-rod gap.
3. Although the appearance of the discharge of the soil around the grounding body can be captured by embedding the X-ray film near the grounding body in the ground, the X-ray film blocks a current dispersion path in the soil due to the parallel and close arrangement of the X-ray film and the grounding rod, so that the discharge around the grounding rod has a larger difference from the actual discharge.
4. Chongqing university adopts the mode of taking a picture in a space X-ray camera to observe soil discharge, but because X-ray attenuation is very fast, the mode can only shoot the strong discharge of a main discharge channel, and discharge branches before and after the main discharge channel is formed cannot be observed.
Disclosure of Invention
Aiming at the problems, the invention provides a method for observing the three-dimensional discharge morphology of soil around a grounding device, which comprises the following steps:
in a darkroom, placing a plurality of layers of x films with holes punched in the middle in a metal cylinder, penetrating a grounding rod through the axis position of the x film metal cylinder, and filling soil in the metal cylinder;
taking out the metal cylinder from the darkroom, placing the metal cylinder in a preset range near the lightning impulse generator, carrying out an impulse current/voltage test on the metal cylinder, and collecting an impulse current waveform on the grounding rod and a potential difference waveform between the grounding rod and the metal cylinder;
after the test is finished, placing the tested metal cylinder in a darkroom, taking out the x film layer by layer, and washing the x film to obtain a soil discharge photo;
and determining the three-dimensional discharge morphology of the soil around the grounding device according to the acquired impact current waveform on the grounding rod, the potential difference waveform between the grounding rod and the metal cylinder and the acquired soil discharge photo.
Optionally, the metal cylinder is of a metal coaxial cylinder structure, the upper part and the lower part of the metal cylinder are respectively provided with a grading ring, and the middle part of the metal cylinder is provided with two insulating rings.
Optionally, the metal cylinder is placed on an insulating table, and a hole is drilled in the middle of the insulating table for penetrating through the ground rod.
Optionally, an x-film is placed between the two insulating rings.
Optionally, the impulse current/voltage test specifically includes:
inserting the bottom end of the grounding rod into soil, and connecting the high-voltage end of the lightning impulse generator with the top end of the grounding rod;
connecting the low-voltage end of the lightning impulse generator with a metal cylinder;
a rush current/voltage is applied across the ground rod and the metal cylinder.
Alternatively, the rush current on the ground bar is measured using a rogowski coil.
Alternatively, the potential difference between the ground rod and the metal cylinder is measured using a ballistic voltage divider.
Optionally, the impulse current waveform on the ground rod and the potential difference waveform between the ground rod and the metal cylinder are collected by an oscilloscope.
The grading rings are arranged at the upper part and the lower part of the metal cylinder, so that no potential difference exists between all parts at the edge of the metal cylinder, the breakdown voltage of air is higher under a uniform electric field, the discharge of a test device is reduced, and the reliability and the safety of a test are improved. The insulating ring is arranged in the middle of the metal cylinder, so that the situation that the impact current flows back along the metal wall edge surface without flowing through soil can be effectively avoided. The film has no influence on the current path, and the real soil discharge morphology can be observed. And multiple layers of X-ray films are embedded at equal intervals along the grounding rod, so that the distribution of discharge along the grounding rod can be captured, and the three-dimensional discharge appearance capture of the soil around the grounding body is realized. The X-ray film covers the place far away from the grounding rod surface and the grounding body, so that local fine discharge, fine branches around the main discharge channel and the main discharge channel can be observed, and the discharge appearance can be observed in all directions.
Drawings
FIG. 1 is a flow chart of the method of the present invention;
FIG. 2 is a diagram of the arrangement of a metal cylinder in the method of the present invention;
FIG. 3(a) is a front view of the arrangement of multiple layers of x film in the method of the present invention;
FIG. 3(b) is a top view of the arrangement of multiple layers of x film in the process of the present invention;
FIG. 4 is a diagram of the development process of the discharge of the soil around the grounding electrode under the lightning strike after the x-film of the present invention is washed.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
The invention provides a method for observing three-dimensional discharge morphology of soil around a grounding device, as shown in figure 1, comprising the following steps:
in a darkroom, placing a plurality of layers of x films with holes punched in the middle in a metal cylinder, penetrating a grounding rod through the axis position of the x film metal cylinder, and filling soil in the metal cylinder;
taking out the metal cylinder from the darkroom, placing the metal cylinder in a preset range near the lightning impulse generator, carrying out an impulse current/voltage test on the metal cylinder, and collecting an impulse current waveform on the grounding rod and a potential difference waveform between the grounding rod and the metal cylinder;
after the test is finished, placing the tested metal cylinder in a darkroom, taking out the x film layer by layer, and washing the x film to obtain a soil discharge photo;
and determining the three-dimensional discharge morphology of the soil around the grounding device according to the acquired impact current waveform on the grounding rod, the potential difference waveform between the grounding rod and the metal cylinder and the acquired soil discharge photo.
The metal cylinder is of a metal coaxial cylinder structure, grading rings are arranged on the upper portion and the lower portion of the metal cylinder respectively, and two insulating rings are arranged in the middle of the metal cylinder.
Wherein, the metal cylinder is placed on the insulating platform, and the insulating platform middle part is bored for passing through the earth bar.
Wherein the x-film is placed between two insulating rings.
The impact current/voltage test specifically comprises the following steps:
inserting the bottom end of the grounding rod into soil, and connecting the high-voltage end of the lightning impulse generator with the top end of the grounding rod;
connecting the low-voltage end of the lightning impulse generator with a metal cylinder;
a rush current/voltage is applied across the ground rod and the metal cylinder.
Wherein the inrush current on the ground rod is measured using an inrush voltage divider.
Wherein the rush current on the ground rod is measured using a rogowski coil.
Wherein the potential difference between the ground rod and the metal cylinder is measured using a ballistic voltage divider.
The following is further illustrated with reference to specific examples:
as shown in fig. 2, the metal cylinder is provided with equalizing rings at the upper and lower parts thereof respectively to ensure that there is no potential difference between the parts at the edge of the metal cylinder, the insulating ring is provided at the middle part of the cylinder body to prevent the impact current from flowing back along the metal cylinder body, the metal cylinder adopts a metal coaxial cylinder structure,
the tested grounding rod is placed on the axis in the cylinder, the cylinder is filled with soil, the coaxial cylinder structure is vertically placed on the insulating table, and a hole is drilled in the middle of the insulating table so that the tested grounding rod can penetrate through the hole. Therefore, the current in the soil around the grounding rod is uniformly distributed in the radial direction perpendicular to the grounding body, and is consistent with the current distribution in the soil near the grounding body of the actual grounding device.
In the process of filling soil around the grounding rod, the middle of the X-ray film is punched in the darkroom, the grounding rod vertically penetrates through the X-ray film and is buried in the soil, and because the film and the current path are both vertical to the grounding rod, the trend of the film and the current path is consistent, the film has no influence on the current path basically.
Multiple layers of X-ray films are embedded at equal intervals along the ground rod, so that the distribution of discharge along the ground rod can be captured. Finally, the coaxial cylindrical structure is filled with soil, and the embedded multilayer X-ray films are shown in FIGS. 3(a) and 3 (b).
Taking out the metal cylinder with the grounding rod and the X-ray film embedded, placing the metal cylinder near a lightning impulse generator, and carrying out the test according to the following steps:
(1) the high-voltage end of the lightning impulse generator is connected to a tested grounding rod;
(2) the low-voltage end of the lightning impulse generator is connected to the metal cylinder;
(3) applying a surge current or voltage to the ground rod and the coaxial cylinder;
(4) measuring the potential difference between the tested grounding rod and the coaxial cylinder structure by adopting an impact voltage divider;
(5) measuring the impulse current of the test section connected to the grounding rod by adopting a Rogowski coil;
(6) the voltage and current waveforms in 4, 5 were observed and recorded using an oscilloscope.
And after the impact current or voltage is applied, the metal cylinder with the grounding rod and the X-ray film embedded therein is put back to the darkroom, the X-ray film is dug layer by layer in the darkroom, and then the picture shot by the X-ray film is washed out.
Soil discharge characteristics were analyzed based on the photographs taken of the soil discharge by the X-ray film and the measured voltage and current, as shown in fig. 4.
The grading rings are arranged at the upper part and the lower part of the metal cylinder, so that no potential difference exists between all parts at the edge of the metal cylinder, the breakdown voltage of air is higher under a uniform electric field, the discharge of a test device is reduced, and the reliability and the safety of a test are improved. The insulating ring is arranged in the middle of the metal cylinder, so that the situation that the impact current flows back along the metal wall edge surface without flowing through soil can be effectively avoided. The film has no influence on the current path, and the real soil discharge morphology can be observed. And multiple layers of X-ray films are embedded at equal intervals along the grounding rod, so that the distribution of discharge along the grounding rod can be captured, and the three-dimensional discharge appearance capture of the soil around the grounding body is realized. The X-ray film covers the place far away from the grounding rod surface and the grounding body, and can simultaneously observe local fine discharge, fine branches around the main discharge channel and the main discharge channel, and observe the discharge appearance in all directions.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein. The scheme in the embodiment of the application can be implemented by adopting various computer languages, such as object-oriented programming language Java and transliterated scripting language JavaScript.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all alterations and modifications as fall within the scope of the application.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such 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 intended to include such modifications and variations as well.
Claims (8)
1. A method of observing a three-dimensional discharge topography of soil surrounding a grounded device, the method comprising:
in a darkroom, placing a plurality of layers of x films with holes punched in the middle in a metal cylinder, penetrating a grounding rod through the axis position of the x film metal cylinder, and filling soil in the metal cylinder;
taking out the metal cylinder from the darkroom, placing the metal cylinder in a preset range near the lightning impulse generator, carrying out an impulse current/voltage test on the metal cylinder, and collecting an impulse current waveform on the grounding rod and a potential difference waveform between the grounding rod and the metal cylinder;
after the test is finished, placing the tested metal cylinder in a darkroom, taking out the x film layer by layer, and washing the x film to obtain a soil discharge photo;
and determining the three-dimensional discharge morphology of the soil around the grounding device according to the acquired impact current waveform on the grounding rod, the potential difference waveform between the grounding rod and the metal cylinder and the acquired soil discharge photo.
2. The method according to claim 1, wherein the metal cylinder is a metal coaxial cylinder structure, the metal cylinder is provided with grading rings respectively at the upper and lower parts, and two insulating rings are arranged in the middle of the metal cylinder.
3. The method of claim 1, wherein the metal cylinder is placed on an insulation table, and a hole is drilled in the middle of the insulation table for passing through the ground rod.
4. The method of claim 1, wherein the x-film is placed between two insulating rings.
5. The method according to claim 1, the inrush current/voltage test being in particular:
inserting the bottom end of the grounding rod into soil, and connecting the high-voltage end of the lightning impulse generator with the top end of the grounding rod;
connecting the low-voltage end of the lightning impulse generator with a metal cylinder;
a rush current/voltage is applied across the ground rod and the metal cylinder.
6. The method of claim 1, wherein the rush current on the ground rod is measured using a Rogowski coil.
7. The method of claim 1, the potential difference of the ground rod and metal cylinder being measured using a kicker divider.
8. The method of claim 1, wherein the impulse current waveform on the ground rod and the potential difference waveform between the ground rod and the metal cylinder are collected using an oscilloscope.
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| CN202110545988.XA CN113311297A (en) | 2021-05-19 | 2021-05-19 | Method for observing three-dimensional discharge morphology of soil around grounding device |
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| CN202110545988.XA CN113311297A (en) | 2021-05-19 | 2021-05-19 | Method for observing three-dimensional discharge morphology of soil around grounding device |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106841942A (en) * | 2017-01-17 | 2017-06-13 | 国家电网公司 | A kind of method for obtaining the lower grounding body surrounding soil ionic discharge starting field intensity of impact |
| CN106896303A (en) * | 2017-04-13 | 2017-06-27 | 深圳供电局有限公司 | The three-dimensional measuring apparatus and method of a kind of power system lightning-proof grounding body spark discharge |
| CN107064755A (en) * | 2017-03-31 | 2017-08-18 | 中国电力科学研究院 | A kind of method and system for determining soil flash-over characteristic |
| CN112415340A (en) * | 2020-10-27 | 2021-02-26 | 清华大学 | Device and method for observing three-dimensional discharge morphology of soil around grounding body |
| CN112485303A (en) * | 2020-12-08 | 2021-03-12 | 国网四川省电力公司电力科学研究院 | Method and system for analyzing characteristic parameters of soil multi-impact discharge |
-
2021
- 2021-05-19 CN CN202110545988.XA patent/CN113311297A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106841942A (en) * | 2017-01-17 | 2017-06-13 | 国家电网公司 | A kind of method for obtaining the lower grounding body surrounding soil ionic discharge starting field intensity of impact |
| CN107064755A (en) * | 2017-03-31 | 2017-08-18 | 中国电力科学研究院 | A kind of method and system for determining soil flash-over characteristic |
| CN106896303A (en) * | 2017-04-13 | 2017-06-27 | 深圳供电局有限公司 | The three-dimensional measuring apparatus and method of a kind of power system lightning-proof grounding body spark discharge |
| CN112415340A (en) * | 2020-10-27 | 2021-02-26 | 清华大学 | Device and method for observing three-dimensional discharge morphology of soil around grounding body |
| CN112485303A (en) * | 2020-12-08 | 2021-03-12 | 国网四川省电力公司电力科学研究院 | Method and system for analyzing characteristic parameters of soil multi-impact discharge |
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