CN106841942B - A method of it obtains and impacts lower grounding body surrounding soil ionic discharge starting field strength - Google Patents
A method of it obtains and impacts lower grounding body surrounding soil ionic discharge starting field strength Download PDFInfo
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- CN106841942B CN106841942B CN201710032007.5A CN201710032007A CN106841942B CN 106841942 B CN106841942 B CN 106841942B CN 201710032007 A CN201710032007 A CN 201710032007A CN 106841942 B CN106841942 B CN 106841942B
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- 239000002689 soil Substances 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 title claims abstract description 15
- 238000012360 testing method Methods 0.000 claims abstract description 24
- 239000004020 conductor Substances 0.000 claims abstract description 7
- 238000005259 measurement Methods 0.000 claims abstract description 7
- 230000003116 impacting effect Effects 0.000 claims abstract description 4
- 239000002184 metal Substances 0.000 claims description 7
- 238000005553 drilling Methods 0.000 claims description 4
- 230000005672 electromagnetic field Effects 0.000 abstract 1
- 230000005611 electricity Effects 0.000 description 4
- 238000000926 separation method Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000010891 electric arc Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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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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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Testing Relating To Insulation (AREA)
- Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
Abstract
The present invention discloses a kind of method for obtaining and impacting lower grounding body surrounding soil ionic discharge starting field strength, using grounding rod and cylinder-shaped return electrode structured testing, by measurement grounding rod and return electrode between soil resistance with application surge voltage change curve, the starting voltage of ionic discharge is derived using the slope of change curve, and corresponding grounding body surrounding soil ionic discharge is obtained by Theory of Electromagnetic Field and originates field strength.Lower grounding body surrounding soil ionic discharge starting field strength is impacted since the resistance variations by soil between grounding rod and cylinder obtain, it is as a result more objective；Due to being tested using grounding rod and cylindrical structure, grounding rod surface field strength is more evenly.The present invention can be used in assessment measurement earth conductor surrounding soil flash-over characteristic, and earth work is instructed to build.
Description
Technical field
The present invention relates to technical field of high voltage, in particular to a kind of measurement earth conductor surrounding soil ionic discharge starting
The method of field strength.
Background technique
It, often need to be by electric system and its certain parts of electrical equipment in the power system in order to work and security needs
Be greatly connected, here it is ground connection.Electric system ground connection can be divided into working earthing, lightning protection and protection for its purpose
Three kinds of ground connection.Wherein lightning protection is the harm in order to avoid thunder and lightning, and the thunder resisting equipments such as lightning rod, lightning conducter and arrester all must
Corresponding earthing or grounding means must be equipped with so that lightning current is imported the earth.
Since lightning current is very big, concentrate diffusing that can generate very high current potential ladder when entering ground in the soil by earthing or grounding means
Degree, more than soil tolerance field strength when, will Discharge Phenomena in soil.The electric discharge of soil will largely effect on earthing or grounding means
Lightning Characteristic causes impulse earthed resistance to become mixed nonlinear change in time-varying and frequency, and influences lightning rod in turn, keeps away
The lightning protection characteristic of thunder line and arrester.Electric discharge in soil is started in the form of ionic discharge first.Therefore having very much must
Study the ionic discharge starting field strength of grounding rod surrounding soil under impact.
The form for the electric discharge research of soil discharging gap used is mainly point-plate, point-point, ball-ball at present, and
Grounding body is usually rodlike in practice, therefore lacks line-sheet separation flash-over characteristic.Due to line sheet separation and point-plate, point-point,
Ball-sphere gap is entirely different, and under line-sheet separation under low current, soil starts partial ionization occur, with the increasing of electric current
Add, ionized space gradually becomes larger, when electric current greatly to certain value after, there is arc discharge in soil.Due to the gradually hair of ionic discharge
Exhibition, it is not suddenly change, is not easy to observe, needs to develop soil ionic discharge starting field strength measurement method.
Summary of the invention
It is an object of the invention to propose a kind of side for obtaining the lower grounding body surrounding soil ionic discharge starting field strength of impact
Method instructs earth work to build for assessing measurement earth conductor surrounding soil flash-over characteristic.
To achieve the goals above, the present invention adopts the following technical scheme:
A method of it obtains and impacts lower grounding body surrounding soil ionic discharge starting field strength, connect based on one kind for observing
The device of ground stick surrounding soil impulsive discharge characteristic, described device include return electrode and subject grounding rod；Return electrode uses
Coaxial metal cylindrical structure, return electrode, divide three sections: both ends are the pressure sections being arranged symmetrically, and middle straight line section is test section；?
Pressing section includes sequentially connected grading ring, quadrant segmental arc and equal straightening line segment；Lead between equal straightening line segment and test section
Insulating concrete cylinder is crossed to separate；Subject grounding rod is placed in return electrode axle center, is tested filling soil between grounding rod and return electrode；?
Pressure section and test section respectively pass through a ground line and are connected with each other, finally by ground connection；Lightning impulse generator high pressure is defeated
It is terminated on subject grounding rod out, low-voltage output connects on the ground line of return electrode；
A kind of obtain impacts the method that lower grounding body surrounding soil ionic discharge originates field strength, specifically includes following step
It is rapid:
1), using coaxial metal cylindrical structure return electrode, tested grounding rod is placed in axle center, is put into soil in return electrode
Earth；
2), return electrode is vertically placed on insulation, and drilling in the middle part of insulating stand is passed through for subject grounding rod；
3), the high pressure of lightning impulse generator terminates on subject grounding rod；
4), the low pressure of lightning impulse generator terminates on ground line；
5) subject grounding rod and the potential difference between coaxial return electrode, are measured using impulse voltage divider, and read with oscillograph
Take time domain waveform；
6), the dash current of measurement lightning impulse generator output, and time domain waveform is read with oscillograph；
7), the charging voltage of lightning impulse generator is stepped up, successively measures step 5) under corresponding charging voltage, 6)
In voltage, electric current；
8) the impulse resistance Rim for, being tested grounding rod, return electrode and the coaxial circles columnar structures of soil constitution is Voltage Peak
Value UmaxWith current peak ImaxThe ratio between:
9), when derivative absolute value of the impulse resistance to surge voltage is greater than threshold alpha, start shelf depreciation occur in soil
Phenomenon, when conductor nearby field strength be ionization starting field strength Ec:
In formula, subject grounding rod radius is ri, return electrode test section radius is ro。
Further, return electrode is vertically placed on insulating stand, and insulating stand includes insulating supporting disk and supports insulative branch
The insulating supporting column of support plate；Drilling in the middle part of insulating supporting disk is passed through for subject grounding rod.
Further, the ground line periphery of test section is equipped with the Rogowski coil for testing electric current.
Further, described device further includes the impact for measuring the potential difference between subject grounding rod and return electrode
Divider.
Further, α=5%.
Compared with the existing technology, the present invention has following the utility model has the advantages that the resistance for passing through soil between grounding rod and cylinder
Variation, which obtains, impacts lower grounding body surrounding soil ionic discharge starting field strength, more objective；It is tested using grounding rod and cylindrical structure,
Grounding rod surface field strength is more evenly.
Detailed description of the invention
Fig. 1 is changing rule schematic diagram of the pedotheque impulse resistance with surge voltage；
Fig. 2 is a kind of for observing the structural schematic diagram of the device of grounding rod surrounding soil impulsive discharge characteristic.
Specific embodiment
It please refers to shown in Fig. 2, the present invention is a kind of to obtain the side for impacting lower grounding body surrounding soil ionic discharge starting field strength
Method, be applied to it is a kind of for observing the device of grounding rod surrounding soil impulsive discharge characteristic, the device include return electrode and by
Try grounding rod 2；Return electrode uses coaxial metal cylindrical structure, and subject grounding rod is placed in axle center.
Return electrode uses coaxial metal cylindrical structure, and divide three sections: both ends are the pressure section 21 being arranged symmetrically, middle straight line
Section 22 is test section.Pressure section 21 includes sequentially connected grading ring 210, quadrant segmental arc 211 and equal straightening line segment
212；It is separated between equal straightening line segment 212 and test section 22 by insulating concrete cylinder 24.
Pressure 21 outer profile of section is by equal straightening line segment and outward quadrant segmental arc 211 structure tangent with it
At.Equal straightening line segment to ensure the electric field in test section, along the test section on direction field distribution consistency, outward
Arc section then guarantees that the creeping discharge of soil will not occur in end four points opened always, in this way, soil discharge scenario can then collect
In in test section region.
It presses between section 21 and test section 22 and carries out electrical isolation using one section of insulating concrete cylinder 24, to prevent from pressing section 21
Soil electric discharge impacts test result.Section 21 and test section 22 is pressed respectively to be connected with each other by a ground line, finally led to
Cross 25 ground connection of ground line；On subject grounding rod, low-voltage output connects in reflux electricity lightning impulse generator High voltage output termination
On the ground line 25 of pole.
The coaxial cylinders structural vertical that return electrode and subject grounding rod 2 form is placed on insulating stand, and insulating stand includes
The insulating supporting column 32 of insulating supporting disk 31 and supports insulative support plate 31；30 are drilled in the middle part of insulating supporting disk 31, so that subject
Earth conductor electrode (subject grounding rod 2) passes through.
One's duty invents a kind of method for obtaining and impacting lower grounding body surrounding soil ionic discharge starting field strength, including following step
It is rapid:
1), using coaxial metal cylindrical structure return electrode, tested grounding rod 2 is placed in axle center, is put into soil in return electrode
Earth.
2), return electrode is vertically placed on insulating stand, drilling in the middle part of insulating stand, so that subject grounding rod passes through.
3), the high pressure of lightning impulse generator terminates on subject grounding rod；
4), the low pressure of lightning impulse generator terminates on ground line；
5) subject grounding rod and the potential difference between coaxial return electrode, are measured using impulse voltage divider, and read with oscillograph
Take time domain waveform；
6), the dash current of measurement lightning impulse generator output, and time domain waveform is read with oscillograph；
7), the charging voltage of lightning impulse generator is stepped up, successively measures step 5) under corresponding charging voltage, 6)
In voltage, electric current.
8), the impulse resistance Rim of definition subject grounding rod, return electrode and the coaxial circles columnar structures of soil constitution is electricity
Voltage crest value UmaxWith current peak ImaxThe ratio between:
9), such as step 7), under the effect of varying strength high-voltage pulse, soil degree of discharge difference will lead to RimDifference, by
This available one group of R corresponding to high-voltage pulse intensityimValue, in non-breakdown phase, RimWith UmaxThe rule of variation is such as Fig. 1 institute
Show.As can be seen that the impulse resistance of soil is still to reduce there is no punch-through when although surge voltage peak value is lower
, illustrate that soil has shelf depreciation generation under the Impulse Voltage, only not yet forms discharge channel, often referred to " ionization "
For the shelf depreciation of this generation in the soil.
10), since ionization gradually increases, voltage and current is not in apparent turning point.In order to fixed
Amount analysis ionization phenomena, introduces the concept of ionization starting field strength, and is calculated as follows and seeks: when impulse resistance is to impact electricity
When the derivative absolute value of pressure is more than or equal to a certain specified value α, it is believed that start partial discharge phenomenon occur in soil, so that impact
Resistance generate variation, will at this time conductor nearby field strength be defined as ionization starting field strength Ec:
In formula, subject grounding rod radius is ri, return electrode test section radius is ro。
For example, general α takes 5%, intuitively understand, R is worked as in α expressionim-UmaxCertain point tangent line and horizontal axle clamp on curve
When angle θ reaches arctan α, then it is assumed that the point is critical point.Using test data carry out interpolation, can difference seek impulse resistance
To the derivative of surge voltage, when meeting critical condition, corresponding soil ionic discharge starting field strength E can be acquiredc。
In test, ro=15cm, riFor 0.5cm, 1.2/50 μ s surge voltage wave is applied to soil, in different charging electricity
It presses under grade, different voltage current waveforms will be correspondingly made available.With 1.0-2.0mm of partial size, the sandy soil that water content is 6.8%
For, pedotheque impulse resistance shown in FIG. 1 is obtained with the changing rule of surge voltage.When α takes 5%, it can be obtained accordingly from Fig. 1
Surge voltage be about 6.12kV, be brought into formula (2) can obtain soil ionic discharge starting field strength EcFor 3.6kV/cm.
Claims (4)
1. a kind of obtain the method for impacting lower grounding body surrounding soil ionic discharge starting field strength, which is characterized in that based on one kind
For observing the device of grounding rod surrounding soil impulsive discharge characteristic, described device includes return electrode and subject grounding rod (2)；
Return electrode uses coaxial metal cylindrical structure, and three sections of return electrode point: both ends are the pressure sections (21) being arranged symmetrically, intermediate straight
Line segment is test section (22)；Pressure section (21) includes sequentially connected grading ring (210), quadrant segmental arc (211) and equal
Straightening line segment (212)；It is separated between equal straightening line segment (212) and test section (22) by insulating concrete cylinder (24)；Return electrode axis
The heart places subject grounding rod (2), is tested filling soil between grounding rod (2) and return electrode；Press section (21) and test section each
It is connected with each other by a ground line, finally by ground connection；Lightning impulse generator High voltage output termination is being tried
On ground stick, low-voltage output is connect on the ground line of return electrode；
A kind of obtain impacts the method that lower grounding body surrounding soil ionic discharge originates field strength, and grounding body uses grounding rod,
Specifically includes the following steps:
1), using coaxial metal cylindrical structure return electrode, subject grounding rod is placed in axle center, is put into soil in return electrode；
2), return electrode is vertically placed on insulating stand, and drilling in the middle part of insulating stand is passed through for subject grounding rod；
3), the high pressure of lightning impulse generator terminates on subject grounding rod；
4), the low pressure of lightning impulse generator terminates on ground line；
5) when, measuring subject grounding rod and the potential difference between coaxial return electrode using impulse voltage divider, and being read with oscillograph
Domain waveform；
6), the dash current of measurement lightning impulse generator output, and time domain waveform is read with oscillograph；
7), the charging voltage of lightning impulse generator is stepped up, successively measure step 5) under corresponding charging voltage, 6) in
Potential difference, electric current；
8), it is tested the impulse resistance R of grounding rod, return electrode and the coaxial circles columnar structures of soil constitutionimFor voltage peak Umax
With current peak ImaxThe ratio between:
9), when impulse resistance is greater than threshold alpha to the derivative absolute value of surge voltage, start shelf depreciation occur in soil existing
As making the conductor starting of field strength ionization nearby field strength Ec:
In formula, subject grounding rod radius is ri, return electrode test section radius is ro。
2. a kind of obtain according to claim 1 impacts the method that lower grounding body surrounding soil ionic discharge originates field strength,
It is characterized in that, return electrode is vertically placed on insulating stand, insulating stand includes insulating supporting disk (31) and supports insulative support
The insulating supporting column (32) of disk (31)；It drills (30) in the middle part of insulating supporting disk (31), is passed through for subject grounding rod (2).
3. a kind of obtain according to claim 1 impacts the method that lower grounding body surrounding soil ionic discharge originates field strength,
It is characterized in that, the ground line periphery of test section is equipped with the Rogowski coil for testing electric current.
4. a kind of obtain according to claim 1 impacts the method that lower grounding body surrounding soil ionic discharge originates field strength,
It is characterized in that, α=5%.
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| CN113311297A (en) * | 2021-05-19 | 2021-08-27 | 中国电力科学研究院有限公司 | Method for observing three-dimensional discharge morphology of soil around grounding device |
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| CN103293419A (en) * | 2013-05-31 | 2013-09-11 | 华南理工大学 | Evaluation method of grounding device impact performance |
| CN103424652A (en) * | 2013-07-30 | 2013-12-04 | 中国电力科学研究院 | Impact performance simulation test method and device for grounding body with large simulated size and large amplitude value |
| KR20150089271A (en) * | 2014-01-27 | 2015-08-05 | 엘에스산전 주식회사 | discriminant method between Partial Discharge signal and imported noise on mold transfomer in switchboard |
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