CN110412395A - Improved grounding net of transformer substation analogue test platform and test method - Google Patents
Improved grounding net of transformer substation analogue test platform and test method Download PDFInfo
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- 238000012360 testing method Methods 0.000 title claims abstract description 75
- 238000010998 test method Methods 0.000 title claims abstract description 22
- 239000002689 soil Substances 0.000 claims abstract description 147
- 229920001817 Agar Polymers 0.000 claims abstract description 57
- 239000008272 agar Substances 0.000 claims abstract description 57
- 238000004088 simulation Methods 0.000 claims abstract description 27
- 238000000034 method Methods 0.000 claims abstract description 16
- 239000002184 metal Substances 0.000 claims abstract description 15
- 238000005259 measurement Methods 0.000 claims abstract description 12
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- 230000001681 protective effect Effects 0.000 claims abstract description 5
- 235000015110 jellies Nutrition 0.000 claims description 44
- 239000008274 jelly Substances 0.000 claims description 44
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 33
- 239000010410 layer Substances 0.000 claims description 22
- 238000002955 isolation Methods 0.000 claims description 18
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 15
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- 239000000843 powder Substances 0.000 claims description 9
- 239000002356 single layer Substances 0.000 claims description 9
- 239000011780 sodium chloride Substances 0.000 claims description 8
- 239000011259 mixed solution Substances 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 150000003839 salts Chemical class 0.000 claims description 3
- 238000003756 stirring Methods 0.000 claims description 3
- 238000009966 trimming Methods 0.000 claims description 3
- 238000005457 optimization Methods 0.000 abstract description 12
- 239000000463 material Substances 0.000 abstract description 7
- 239000000243 solution Substances 0.000 abstract description 6
- 238000002347 injection Methods 0.000 abstract description 4
- 239000007924 injection Substances 0.000 abstract description 4
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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
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
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Abstract
The invention discloses improved grounding net of transformer substation analogue test platform and test methods; test platform is made of isolating transformer, pressure regulator, electrolytic cell and protective resistance; in the selection of protective resistance, the resistance for testing the power limit of isolating transformer, the fault current of injection and metal box used is comprehensively considered；The application method, which freezes system using agar, to be made to simulate blocky soil, and agar freezes body and is integrally formed with ground connection pessimistic concurrency control.By changing the resistivity for simulating blocky soil, the blocky soil size of finishing simulation, variable is controlled to carry out soil resistivity class, soil range class correlation test, while also can be carried out the grounded screens improved tests such as the optimization of grounded screen material, grounded screen whole design optimization.The present invention can improve measurement result accuracy, and provide blocky soil class and test the solution that can not carry out problem, can carry out experimental study to the blocky soil issues under simple blocky soil issues and two-layer soil structure.
Description
Technical Field
The invention relates to the technical field of grounding grid overvoltage, in particular to an improved transformer substation grounding grid simulation test platform and a test method.
Background
The environment of the transformer substation is complex, and large-scale large-current experiments may damage various primary equipment and secondary equipment which are used in large quantities in the substation, so that fewer experiments are allowed; meanwhile, the operation time of the transformer substation is relatively long, the overhaul time is relatively short, the work in the aspect of scientific research is relatively complex, the incoordination in time is not beneficial to relevant experiments of the grounding grid, and the influence of seasons and accidental factors is large.
In recent years, in order to research soil problems, a soil model structure of a grounding grid is not limited to a single soil horizontal layered structure or a single soil vertical layered structure, and in recent years, a block soil structure with different soil resistivity and same internal resistivity in different regions of the same region exists. The difficulty of the research of grounding problems is increased by the massive soil structure.
At present, the main problems of the research on the grounding grid of the transformer substation are that the grounding overvoltage experiment is difficult to implement, and the experimental research on the grounding grid is less due to the limitation of the field environment and the cost, so that the research enthusiasm of researchers on the grounding grid overvoltage experiment is greatly influenced, and the scientificity and the practicability of related research achievements are also reduced. On the other hand, as the research on the soil in the transformer substation area is deeper and the problem of the massive soil is caused, the threshold and the difficulty of the overvoltage test of the grounding grid are higher and higher, and how to solve the experimental problem of the grounding grid under the condition is the research direction in the future.
The existing grounding grid simulation test method has large limitation: on one hand, the simulated soil structure is simple, the problems of complex soil structures such as block soil and the like are solved, the accuracy and the practicality of the test result are questioned, and the research on the block soil problems under the simple block soil structure and the multilayer soil structure cannot be carried out; secondly, the existing simulation test method has insufficient flexibility in the test of control variable classes, and the simulated fault current has a promotion space.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide an improved transformer substation grounding grid simulation test platform and a test method, and aims to solve the problems that the existing grounding grid simulation test method is large in limitation, simple in simulated soil structure and insufficient in flexibility in tests of control variables.
The purpose of the invention is realized by adopting the following technical scheme:
an improved transformer substation grounding grid simulation test platform comprises an isolation transformer, a voltage regulator, a protection resistor and an electrolytic cell which are connected in sequence; wherein,
and a grounding net model and a medium for simulating soil are arranged in the electrolytic cell.
On the basis of the above embodiment, it is preferable that the medium for simulating soil includes agar jelly, water;
the grounding net model and the agar jelly for simulating the blocky soil are arranged at the top inside the electrolytic cell;
water for simulating single-layer soil is arranged in the electrolytic bath; or,
water for simulating upper soil of double-layer soil is arranged in the middle of the inside of the electrolytic bath; the agar jelly for simulating the bottom soil of the double-layer soil is arranged at the bottom inside the electrolytic cell.
In any of the above embodiments, preferably, the electrolytic cell is a metal electrolytic cell;
the radius of the metal electrolytic tank is more than twice the length of the diagonal line of the grounding grid model;
the shape of the metal electrolytic tank is square or hemispherical.
On the basis of any embodiment, the electrolytic cell preferably further comprises a wooden frame arranged above the electrolytic cell and cotton threads connected with the wooden frame;
the fixing of the agar jelly for simulating the block soil is realized by cotton threads.
An improved transformer substation grounding grid simulation test method comprises the following steps:
a resistance step, selecting a protection resistance;
a natural step, preparing a medium in an electrolytic cell according to actual needs, and simulating natural soil; the natural soil comprises single-layer soil and/or double-layer soil;
a block step, namely manufacturing an agar jelly body containing a grounding grid model in a mould and simulating block soil;
the method comprises the steps of assembling, namely fixing the massive soil at a proper position in an electrolytic bath, and connecting each test instrument by using a lead;
a measuring step, namely switching on a power supply, injecting fault current into corresponding fault points on the massive soil, and carrying out required measuring work;
and testing, namely changing the resistivity of the block soil, trimming the size of the block soil, and controlling variables to perform related tests of the soil resistivity class and the soil range class.
On the basis of the above embodiment, preferably, the resistance step includes:
step S11, determining the combined resistance of the grounding grid model, the medium and the electrolytic cell through preliminary measurement;
step S12, selecting a high-power resistor as a protection resistor, and determining the use limit of the high-power resistor; the usage limit of the high power resistor includes power;
step S13, judging whether the selected protection resistor is matched with the combined resistor, if not, returning to the step S12;
step S14, if the protection resistance matches the combined resistance, then a preliminary simulated fault current I is determinedx；
Step S15, according to IxCalculating the integral power of the electrolytic cell and the protection resistor, and judging whether the integral power exceeds the power limit of the isolation transformer and the voltage regulator and a certain margin is reserved; wherein the power limitations of the isolation transformer and the voltage regulator are related to the usage limitations of the high power resistor;
step S16, if the margin is exceeded or the margin is insufficient, the method returns to the step S12 to reselect the protection resistor, or reselect the isolation transformer or the voltage regulator;
and step S17, if the power is not exceeded and the margin is appropriate, completing the matching design of the protection resistor and the test platform, and ending the selection of the protection resistor.
Alternatively, preferably, the natural step includes:
preparing water as a medium in an electrolytic cell, and simulating single-layer soil; or,
agar jelly is prepared as a bottom medium and water is prepared as an upper medium in an electrolytic cell to simulate double-layer soil.
On the basis of the above examples, it is preferable that the resistivity of both agar jelly and water can be adjusted by adding the content of common salt.
Or, preferably, the blocking step includes:
fixing the grounding net model in a mold by using cotton threads;
dissolving a certain amount of NaCl in water, adding a certain amount of agar powder, uniformly stirring, heating, and pouring the hot mixed solution into a custom-made mold;
and cooling the mixed solution to obtain the agar jelly simulating the blocky soil.
Or, preferably, in the block-shaped step, after the step of fixing the ground net model in the mold with cotton, the method further includes:
lead-in wires of failure points are arranged in a mould in advance, so that the lead-in wires are integrally formed when the blocky soil is manufactured.
Compared with the prior art, the invention has the beneficial effects that:
the invention discloses an improved transformer substation grounding grid simulation test platform and a test method, which mainly comprise an improved test platform and an application method thereof. The test platform comprises a test platform main body, a test platform control module and a control module, wherein the test platform main body comprises an isolation transformer, a voltage regulator, an electrolytic cell and a protection resistor, and the power limit of the isolation transformer, the injected fault current and the resistance of a metal box used in the test are comprehensively considered in the selection of the protection resistor; and secondly, an improved grounding simulation test method is characterized in that agar jelly is used for manufacturing simulated block-shaped soil, and the agar jelly and a grounding grid model are integrally formed. The resistivity of the simulated block soil is changed, the size of the simulated block soil is trimmed, and the variable is controlled to perform soil resistivity type and soil range type related tests, and simultaneously, grounding grid improvement tests such as grounding grid material optimization, grounding grid overall design optimization and the like can also be performed. The invention can improve the accuracy of the measurement result, simulate the overvoltage test of the transformer substation grounding grid with higher accuracy, provide a solution for solving the problem that the block soil test cannot be carried out, carry out test research on the simple block soil problem and the block soil problem under the double-layer soil structure, and provide a new research idea for the influence research of the block soil under the multi-layer soil.
The test platform provided by the invention has the advantages that the protection resistor is reasonably selected according to the actual situation, so that the larger injection current can be ensured to be obtained, the accuracy of the measurement result is improved, and the test effect is closer to the actual field test; according to the invention, the simulated block-shaped soil is prepared by using the agar jelly, and the agar jelly and the grounding grid model are integrally formed, so that the stability of the simulated block-shaped soil is ensured, the accuracy of a test result is improved, and meanwhile, grounding grid improvement tests such as grounding grid material optimization, grounding grid overall design optimization and the like can be carried out; the invention provides a solution which can not be carried out by block soil tests, and control variable tests of parameters such as resistivity, range and the like of the block soil can be carried out according to the method; meanwhile, a new test method is provided for the research on the influence of massive soil under multilayer soil.
Drawings
FIG. 1 is a flow chart illustrating test platform protection resistance selection according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram illustrating an improved simulation test platform for a substation grounding grid according to an embodiment of the present invention;
FIG. 3 is a schematic diagram showing the position relationship between a measuring line and the boundary of a grounding grid model and an agar jelly in simulated massive soil according to an embodiment of the invention;
FIG. 4 is a graph showing the variation of the step voltage with the resistivity of agar when the size of simulated soil blocks obtained by measurement is 26cm × 26 cm;
fig. 5 shows a flow chart of an improved transformer substation grounding grid simulation test method provided by an embodiment of the present invention.
In the figure, 1, an isolation transformer; 2. a voltage regulator; 3. a protection resistor; 4. an electrolytic cell; 5. a ground net model; 6. agar jelly for simulating block soil; 7. water used for simulating upper soil under double-layer soil condition; 8. agar jelly used to simulate the bottom soil in the case of double layers of soil.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and the detailed description, and it should be noted that any combination of the embodiments or technical features described below can be used to form a new embodiment without conflict.
Detailed description of the preferred embodiment
As shown in fig. 2, an embodiment of the present invention provides an improved transformer substation grounding grid simulation test platform, which includes an isolation transformer, a voltage regulator, a protection resistor, and an electrolytic cell, which are connected in sequence; wherein, a grounding net model and a medium for simulating soil are arranged in the electrolytic cell.
For example, the scale of the model may be 100, the size of the ground net model used may be 20cm × 20cm, the number of meshes may be 4 × 4, the diameter of the conductor may be 2mm, and the buried depth may be 0.8 cm.
Preferably, the medium for simulating soil may include agar jelly, water;
the grounding net model and the agar jelly for simulating the blocky soil are arranged at the top inside the electrolytic cell;
water for simulating single-layer soil is arranged in the electrolytic bath; alternatively, as shown in FIG. 2,
water for simulating upper soil of double-layer soil is arranged in the middle of the inside of the electrolytic bath; the agar jelly for simulating the bottom soil of the double-layer soil is arranged at the bottom inside the electrolytic cell.
In the embodiment of the invention, the material, size and shape of the electrolytic bath are not limited, preferably, the electrolytic bath is a metal electrolytic bath; the radius of the metal electrolytic tank is more than twice the length of the diagonal line of the grounding grid model; the shape of the metal electrolytic tank is square or hemispherical, and is selected according to actual conditions. In this case, the electrolytic bath is a metal water tank, and the length, width and height thereof may be, for example, 114cm × 114cm × 30 cm.
Preferably, the embodiment of the invention also comprises a wood frame arranged above the electrolytic bath and cotton threads connected with the wood frame; the fixing of the agar jelly for simulating the block soil is realized by cotton threads.
In the first embodiment, an improved transformer substation grounding grid simulation test platform is provided, and correspondingly, an improved transformer substation grounding grid simulation test method is also provided. Since the method embodiment is basically similar to the platform embodiment, the description is simple, and the relevant points can be referred to the partial description of the platform embodiment. The method embodiments described below are merely illustrative.
Detailed description of the invention
As shown in fig. 5, an embodiment of the present invention provides an improved transformer substation grounding grid simulation test method, including:
a resistance step S1 of selecting a protection resistance;
a natural step S2, preparing a medium in the electrolytic cell according to actual needs, and simulating natural soil; the natural soil comprises single-layer soil and/or double-layer soil;
a block step S3, manufacturing agar jelly containing a grounding grid model in a mould, and simulating block soil;
an assembling step S4, fixing the block soil at a proper position in the electrolytic bath, and connecting each test instrument by using a lead;
a measuring step S5, switching on a power supply, injecting fault current into the corresponding fault point on the massive soil, and carrying out required measuring work;
and a test step S6, changing the resistivity of the block soil, trimming the size of the block soil, and controlling variables to perform related tests of the soil resistivity class and the soil range class.
In the selection of the protective resistance, the power limit of the isolation transformer used in the test, the injected fault current and the resistance of the metal electrolysis cell need to be considered comprehensively. In order to obtain the largest possible analog current, considering the reasonable fit of the testing instrument, as shown in fig. 1, it is preferable that the resistance step S1 includes:
step S11, determining the combined resistance of the grounding grid model, the medium and the electrolytic cell through preliminary measurement; for example, in one application scenario of an embodiment of the present invention, the resistance of the cell and agar jelly is initially measured at about 10 Ω;
step S12, selecting a high-power resistor as a protection resistor, and determining the use limit of the high-power resistor; the usage limit of the high power resistor includes power;
step S13, judging whether the selected protection resistor is matched with the combined resistor, if not, returning to the step S12;
step S14, if the protection resistance matches the combined resistance, then a preliminary simulated fault current I is determinedx；
Step S15, according to IxCalculating the integral power of the electrolytic cell and the protection resistor, and judging whether the integral power exceeds the power limit of the isolation transformer and the voltage regulator and a certain margin is reserved; wherein the power limitations of the isolation transformer and the voltage regulator are related to the usage limitations of the high power resistor;
step S16, if the margin is exceeded or the margin is insufficient, the method returns to the step S12 to reselect the protection resistor, or reselect the isolation transformer or the voltage regulator;
and step S17, if the power is not exceeded and the margin is appropriate, completing the matching design of the protection resistor and the test platform, and ending the selection of the protection resistor.
In an application scenario of the embodiment of the invention, the power of the existing isolation transformer is 1000W, the power of the voltage regulator is 5000W, the protection resistance with required parameters of about 10 Ω and 250W is estimated through a flow chart in consideration of the whole power limitation and the safety and stability of a test process, and the injection fault current is simulated by 5A. The market has almost no high-power low-resistance resistor, so 5 resistors of 50 omega and 50W can be selected to be connected in parallel to replace the protective resistor, and the test result proves that the scheme is feasible.
After the measurement of a measuring instrument, the conductivity of the used water is about 898gS/cm, namely the resistivity is 11.13 omega m, and the used water is used as the upper layer of the double-layer soil; taking water, NaCl and agar powder in a mass ratio of 100: 0.05: 1, mixed as a lower layer of double-layer soil, measured to have a resistivity of about 6.26 Ω m. The resistivity can be considered to be unchanged, considering that the temperature does not change much during the measurement. Preferably, the natural step S2 may include:
preparing water as a medium in an electrolytic cell, and simulating single-layer soil; or,
agar jelly is prepared as a bottom medium and water is prepared as an upper medium in an electrolytic cell to simulate double-layer soil.
Wherein the resistivity of agar jelly and water can be adjusted by adding salt.
Preferably, the block step S3 may include:
fixing the grounding net model in a mold by using cotton threads; for example, a ground net model is fixed in a mold with a cotton thread of 0.8mm in diameter in advance;
dissolving a certain amount of NaCl in water, adding a certain amount of agar powder, uniformly stirring, heating, and pouring the hot mixed solution into a custom-made mold;
and cooling the mixed solution to obtain the agar jelly simulating the blocky soil.
The mass ratio of agar powder used for simulating the blocky soil to water is 3.5:100, and the formed agar jelly has certain strength. Meanwhile, the resistivity of the agar jelly can be relatively accurately adjusted in the test. When in test, firstly, the agar jelly with low resistivity is prepared, and the mass ratio of water to NaCl to agar powder is 100: 0.42: 3.5, the resistivity of the shaped agar jelly was about 0.95. omega. m.
The agar powder and water used in the test need to reach a certain mass ratio, the formed agar jelly has a certain strength, and the integrity of the agar jelly cannot be damaged after the grounding net model is lifted by cotton threads in a metal box. And secondly, performing grounding grid improvement tests such as grounding grid material optimization, grounding grid overall design optimization and the like.
The resistivity of both water and simulated soil blocks can be adjusted relatively accurately by varying the amount of salt added, whereby controlled variable type tests can be accomplished.
Preferably, the block step S3, after the step of fixing the ground net model in the mold with cotton, may further include: lead-in wires of failure points are arranged in a mould in advance, so that the lead-in wires are integrally formed when the blocky soil is manufactured.
Fig. 3 shows the relationship between the measurement lines performed and the simulated soil block, and discusses the effect of changes in the resistivity of the soil block on the performance of the earth mat. In the first step, agar jelly with the length and width of 26cm multiplied by 26cm and the thickness of 1cm is manufactured in a mould to simulate surface block soil with the length and width of 26m multiplied by 26m and the depth of 1m, wherein the center of a grounding net model conductor is positioned at the agar depth of 0.8 cm. The 5A fault current is injected at the center O point, and the ground potential of the critical area on the left side of the O point is measured. The diameter of the measuring probe used is 2mm, the measuring probe penetrates into the water surface by 1mm, the measuring probe is used for measuring, starting from x being 42cm, taking a point every 0.1cm until x being 50cm, and obtaining 81 points in total, and further obtaining the step voltage distribution.
Fig. 4 is a schematic diagram illustrating the influence of different resistivities of the bulk soil on the secondary peak of the step voltage in the embodiment, wherein the mass ratio of water to NaCl to agar powder is 100: 0.16: 3.5, taking water, NaCl and agar powder in a mass ratio of 100: 0.09: 3.5, the resistivity of the shaped agar jelly was about 1.96. omega. m and 3.75. omega. m, and the previous procedure was repeated. And continuously changing the simulated block resistivity for comparison so as to discuss the influence of the change of the block soil resistivity on the performance of the grounding network.
In the embodiment of the invention, on the selection of the protection resistor, the power limit of an isolation transformer used in the test, the injected fault current and the resistance of the metal box are comprehensively considered; the simulated block-shaped soil is made of agar jelly, and the agar jelly and the grounding grid model are integrally formed. The resistivity of the simulated block soil is changed, the size of the simulated block soil is trimmed, and the variable is controlled to perform soil resistivity type and soil range type related tests, and simultaneously, grounding grid improvement tests such as grounding grid material optimization, grounding grid overall design optimization and the like can also be performed. The embodiment of the invention can improve the accuracy of the measurement result, simulate the overvoltage test of the transformer substation grounding grid with higher accuracy, provide a solution for solving the problem that the block soil test cannot be carried out, carry out test research on the simple block soil problem and the block soil problem under the double-layer soil structure, and provide a new research idea for the influence research of the block soil under the multi-layer soil.
According to the embodiment of the invention, the protection resistor can be reasonably selected according to actual conditions, so that a larger injection current can be ensured to be obtained, the accuracy of a measurement result is improved, and the test effect is closer to that of an actual field test; the simulated block-shaped soil is manufactured by using the agar jelly, and the agar jelly and the grounding grid model are integrally formed, so that the stability of the simulated block-shaped soil is guaranteed, the accuracy of a test result is improved, and meanwhile, grounding grid improvement tests such as grounding grid material optimization, grounding grid overall design optimization and the like can be performed; the method provides a solution which can not be carried out by the block soil test, and can carry out the control variable tests of parameters such as the resistivity, the range and the like of the block soil according to the method; meanwhile, a new test method is provided for the research on the influence of massive soil under multilayer soil.
The present invention has been described in terms of its practical application, and it is to be understood that the above description and drawings are only illustrative of the presently preferred embodiments of the invention and are not to be considered as limiting, since all changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. Although the present invention has been described to a certain extent, it is apparent that appropriate changes in the respective conditions may be made without departing from the spirit and scope of the present invention. It is to be understood that the invention is not limited to the described embodiments, but is to be accorded the scope consistent with the claims, including equivalents of each element described. Various other modifications and changes may be made by those skilled in the art based on the above-described technical solutions and concepts, and all such modifications and changes should fall within the scope of the claims of the present invention.
Claims (10)
1. An improved transformer substation grounding grid simulation test platform is characterized by comprising an isolation transformer, a voltage regulator, a protective resistor and an electrolytic bath which are sequentially connected; wherein,
and a grounding net model and a medium for simulating soil are arranged in the electrolytic cell.
2. The improved substation grounding grid simulation test platform of claim 1, wherein the medium for simulating soil comprises agar jelly, water;
the grounding net model and the agar jelly for simulating the blocky soil are arranged at the top inside the electrolytic cell;
water for simulating single-layer soil is arranged in the electrolytic bath; or,
water for simulating upper soil of double-layer soil is arranged in the middle of the inside of the electrolytic bath; the agar jelly for simulating the bottom soil of the double-layer soil is arranged at the bottom inside the electrolytic cell.
3. The improved substation grounding grid simulation test platform of claim 1 or 2, wherein the electrolytic cell is a metal electrolytic cell;
the radius of the metal electrolytic tank is more than twice the length of the diagonal line of the grounding grid model;
the shape of the metal electrolytic tank is square or hemispherical.
4. The improved transformer substation grounding grid simulation test platform according to claim 1 or 2, further comprising a wooden frame arranged above the electrolytic cell and cotton wires connected with the wooden frame;
the fixing of the agar jelly for simulating the block soil is realized by cotton threads.
5. An improved transformer substation grounding grid simulation test method is characterized by comprising the following steps:
a resistance step, selecting a protection resistance;
a natural step, preparing a medium in an electrolytic cell according to actual needs, and simulating natural soil; the natural soil comprises single-layer soil and/or double-layer soil;
a block step, namely manufacturing an agar jelly body containing a grounding grid model in a mould and simulating block soil;
the method comprises the steps of assembling, namely fixing the massive soil at a proper position in an electrolytic bath, and connecting each test instrument by using a lead;
a measuring step, namely switching on a power supply, injecting fault current into corresponding fault points on the massive soil, and carrying out required measuring work;
and testing, namely changing the resistivity of the block soil, trimming the size of the block soil, and controlling variables to perform related tests of the soil resistivity class and the soil range class.
6. The improved substation grounding grid simulation test method of claim 5, wherein the resistance step comprises:
step S11, determining the combined resistance of the grounding grid model, the medium and the electrolytic cell through preliminary measurement;
step S12, selecting a high-power resistor as a protection resistor, and determining the use limit of the high-power resistor; the usage limit of the high power resistor includes power;
step S13, judging whether the selected protection resistor is matched with the combined resistor, if not, returning to the step S12;
step S14, if the protection resistance matches the combined resistance, then a preliminary simulated fault current I is determinedx；
Step S15, according to IxCalculating the integral power of the electrolytic cell and the protection resistor, and judging whether the integral power exceeds the power limit of the isolation transformer and the voltage regulator and a certain margin is reserved; wherein the power limitations of the isolation transformer and the voltage regulator are related to the usage limitations of the high power resistor;
step S16, if the margin is exceeded or the margin is insufficient, the method returns to the step S12 to reselect the protection resistor, or reselect the isolation transformer or the voltage regulator;
and step S17, if the power is not exceeded and the margin is appropriate, completing the matching design of the protection resistor and the test platform, and ending the selection of the protection resistor.
7. The improved substation grounding grid simulation test method of claim 5, wherein the natural steps comprise:
preparing water as a medium in an electrolytic cell, and simulating single-layer soil; or,
agar jelly is prepared as a bottom medium and water is prepared as an upper medium in an electrolytic cell to simulate double-layer soil.
8. The improved simulation test method for the grounding grid of the transformer substation as claimed in claim 7, wherein the resistivity of the agar jelly and the resistivity of the water can be adjusted by adding the content of the salt.
9. The improved substation grounding grid simulation test method of claim 5, wherein the block-like step comprises:
fixing the grounding net model in a mold by using cotton threads;
dissolving a certain amount of NaCl in water, adding a certain amount of agar powder, uniformly stirring, heating, and pouring the hot mixed solution into a custom-made mold;
and cooling the mixed solution to obtain the agar jelly simulating the blocky soil.
10. The improved transformer substation grounding grid simulation test method according to claim 5, wherein in the block step, after the step of fixing the grounding grid model in the mold by using cotton wires, the method further comprises the following steps:
lead-in wires of failure points are arranged in a mould in advance, so that the lead-in wires are integrally formed when the blocky soil is manufactured.
Priority Applications (1)
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