CN111859583A - Grounding grid of railway traction substation in plateau mountainous area and its construction method - Google Patents

Abstract

The invention relates to a plateau mountain railway traction substation grounding grid and a construction method thereof. The construction method comprises the following steps: constructing a soil model of a traction substation with high fill and frozen plateau soil, and dividing the soil model into at least three soil layers; the at least three soil layers comprise at least one frozen soil layer, at least one filling layer positioned on the upper side of the frozen soil layer and at least one auxiliary layer positioned on the lower side of the frozen soil layer; determining the ground short-circuit current of the traction substation; establishing a layered and distributed three-dimensional grounding network; the three-dimensional grounding grid comprises at least three layers of grounding grids, wherein at least one layer of grounding grid is positioned on the auxiliary layer, at least one layer of grounding grid is positioned on the filling layer and is used as an equipment grounding grid, and at least one layer of grounding grid is positioned between the equipment grounding grid and the grounding grid in the auxiliary layer, and the adjacent layers of grounding grids are electrically connected; judging whether the three-dimensional grounding grid meets the grounding requirement or not based on the grounding short-circuit current and the grounding grid parameters of the three-dimensional grounding grid; if not, the three-dimensional grounding grid is adjusted until the grounding requirement is met.

Description

Grounding grid of railway traction substation in plateau mountainous area and its construction method

technical field

The present disclosure relates to the technical field of grounding systems for traction substations, and in particular, to a grounding grid for railway traction substations in plateau mountainous areas and a construction method thereof.

Background technique

With the development of society, electrified railways are gradually extended to the mountainous and plateau areas. Among them, the terrain of railways in mountainous areas is complex, often accompanied by the geological conditions of vertical and horizontal ravines, high mountains and deep valleys, and the proportion of bridges and tunnels on the lines is high. Setting up traction substations in mountainous areas often requires a much smaller field area than in plain areas, which also limits the area of the substation's grounding grid. and personal safety.

At the same time, valleys and rivers are usually distributed in mountainous areas, and traction substations located in these areas are threatened by flooding. The water level rises in the rainy season, and the water level in the canyon can rise several meters higher than that in the dry season. In order to ensure the safety of the site, according to the design specifications, the elevation of the traction substation site must be above the 100-year flood level, and the elevation of the substation and AT site must be above the 50-year flood level. Ping must be filled with high fill, and the century-old flood level of some projects is ten meters or even tens of meters higher than the original ground. A large number of fill works are required for traction substations. The filling material is mostly crushed stone, and the soil resistivity is high, basically above 1000Ω·m, which is very unfavorable to the grounding system.

Due to the cold winter, the plateau area has seasonal or permafrost, and the soil resistivity varies greatly in different seasons, which brings greater uncertainty and instability to the performance of the grounding grid buried in it. To sum up, the grounding grid design of the traction substation of the plateau mountain railway faces many difficulties.

SUMMARY OF THE INVENTION

In order to solve the above technical problems or at least partially solve the above technical problems, the present disclosure provides a grounding grid of a railway traction substation in plateau mountainous areas and a construction method thereof, which are applicable to the terrain and geological conditions of railways in plateau mountainous areas, and can simplify the grounding Network construction difficulty.

The present disclosure provides a construction method for the grounding grid of a railway traction substation in plateau mountainous areas, the construction method comprising:

Build a soil model of a traction substation with high fill and plateau permafrost, and divide the soil model into at least three soil layers; the at least three soil layers include at least one permafrost layer, located in the permafrost layer at least one fill layer on the upper side and at least one auxiliary layer on the lower side of the frozen soil layer;

Determine the short-circuit current into the ground of the traction substation;

A layered and distributed three-dimensional grounding grid is established; the three-dimensional grounding grid includes at least three layers of ground grids, at least one layer of ground grids is located on the auxiliary layer, and at least one layer of ground grids is located on the fill layer and serves as an equipment ground grid , and at least one layer of ground grid is located between the equipment ground grid and the ground grid in the auxiliary layer, and the ground grids of adjacent layers are electrically connected;

Judging whether the three-dimensional grounding grid meets the grounding requirement based on the short-circuit current into the ground and the grounding grid parameters of the three-dimensional grounding grid;

If not, adjust the three-dimensional grounding grid until the grounding requirements are met.

Optionally, dividing the soil model into at least three soil layers includes:

Equivalent processing is performed on the soil model according to the horizontal layers, and the soil model is divided into at least three soil layers according to the resistivity of the soil.

Optionally, before building a soil model of a traction substation with high fill and plateau permafrost, and dividing the soil model into at least three soil layers, the method further includes:

Obtain a terrain model of high fill, plateau permafrost, and determine the resistivity of the soil at each location in the terrain model.

Optionally, the determining the short-circuit current to the ground of the traction substation includes:

Based on the system short-circuit capacity, grounding resistance and the external power line model of the traction substation, the shunt coefficient is calculated to determine the short-circuit current into the ground of the traction substation.

Optionally, the ground grids of each layer are made of metal conductor material, and the ground grids of adjacent layers are electrically connected by metal conductors.

Optionally, the method of adjusting the three-dimensional grounding grid includes at least one of the following:

Enlarging the laying area of at least one layer of the ground net;

increasing the depth of the ground mesh in the auxiliary layer; and

Increase the number of layers of the ground grid.

Optionally, meeting the grounding requirements includes: the grounding resistance, the grounding potential, and the step potential all meet the safety threshold range.

The present disclosure also provides a grounding grid of a railway traction substation in plateau mountainous areas, which can be constructed by applying the above construction method, and the grounding grid includes:

A three-dimensional grounding grid composed of at least three layers of ground grids, the three-dimensional grounding grid is associated with the soil model; wherein at least one layer of ground grids is located on the auxiliary layer, and at least one layer of ground grids is located on the fill layer and is grounded as equipment The grid and at least one layer of ground grid are located between the equipment ground grid and the ground grid in the auxiliary layer, and the ground grids on adjacent layers are electrically connected; the three-dimensional ground grid meets the grounding requirements.

Optionally, along the direction in which the auxiliary layer points to the filling layer, the density of the mesh holes of the ground net increases sequentially.

Compared with the prior art, the technical solutions provided by the embodiments of the present disclosure have the following advantages: building a soil model based on high fill and plateau permafrost, and dividing it into at least three layers including a permafrost layer, a fill layer and an auxiliary layer Soil layer, a layered and distributed three-dimensional grounding grid is established based on the soil model, and at least one layer of grounding grid in the three-dimensional grounding grid is located under the frozen soil layer, and at least one layer of grounding grid serves as the equipment grounding grid and the intermediate grounding grid. The grid can be set to at least one layer according to the soil thickness in the soil model; after that, it is judged whether the three-dimensional grounding grid meets the grounding requirements based on the grounding grid parameters of the three-dimensional grounding grid and the short-circuit current into the ground of the traction substation, and when not Adjust it when satisfied until it meets the grounding requirements. In this way, the three-dimensional grounding grid can be adapted to the topography and geological conditions of the plateau and mountainous areas, and by forming a layered and distributed three-dimensional grounding grid, the problem of limited horizontal layout area of the grounding grid can be compensated for by extending in the vertical direction. The grounding grid that meets the grounding requirements is laid out in a limited and small area, which reduces the requirements for the environment, thereby reducing the difficulty of building the grounding grid.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the disclosure and together with the description serve to explain the principles of the disclosure.

In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the accompanying drawings that are required to be used in the description of the embodiments or the prior art will be briefly introduced below. In other words, on the premise of no creative labor, other drawings can also be obtained from these drawings.

1 is a schematic flowchart of a method for constructing a grounding grid of a railway traction substation in plateau mountainous areas according to an embodiment of the present disclosure;

2 is a schematic structural diagram of a grounding grid of a railway traction substation in plateau mountainous areas provided by an embodiment of the present disclosure;

FIG. 3 is a schematic structural diagram of another grounding grid of a railway traction substation in plateau mountainous areas according to an embodiment of the present disclosure.

Detailed ways

In order to more clearly understand the above objects, features and advantages of the present disclosure, the solutions of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features in the embodiments may be combined with each other under the condition of no conflict.

Many specific details are set forth in the following description to facilitate a full understanding of the present disclosure, but the present disclosure can also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only a part of the embodiments of the present disclosure, and Not all examples. The various embodiments of the present disclosure generally described and illustrated in the drawings herein may be combined with each other without conflict, and the structural components or functional modules therein may be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the disclosure provided in the accompanying drawings is not intended to limit the scope of the disclosure as claimed, but is merely representative of selected embodiments of the disclosure. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present disclosure.

In the description of the present disclosure, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the disclosed product is usually placed in use, only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying References to devices or elements must have, be constructed, and operate in a particular orientation and are therefore not to be construed as limitations of the present disclosure. Furthermore, relational terms such as the terms "first," "second," "third," etc. are used only to distinguish one entity or operation from another, and do not necessarily require or imply that such entities or operations are There is no such actual relationship or sequence between operations. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device that includes a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in a process, method, article or apparatus that includes the element. Furthermore, the terms "horizontal", "vertical", "overhanging" etc. do not imply that a component is required to be absolutely horizontal or overhang, but rather may be slightly inclined. For example, "horizontal" only means that its direction is more horizontal than "vertical", it does not mean that the structure must be completely horizontal, but can be slightly inclined.

In the description of the present disclosure, it should also be noted that, unless otherwise expressly specified and limited, the terms "arranged", "installed", "connected" and "connected" should be understood in a broad sense, for example, it may be a fixed connection, It can also be a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or the internal communication between the two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood in specific situations.

The grounding grid of the railway traction substation in the plateau mountainous area and the construction method thereof provided by the embodiments of the present disclosure, by constructing a layered and distributed three-dimensional grounding grid structure according to the soil geological conditions in the plateau mountainous area, and adjusting the structural parameters of the grounding grid , so that the grounding grid can be adapted to the terrain and geological conditions of the railway in the plateau and mountainous areas, so that the grounding grid can meet the purpose of compliance, economy and long-term effect. The grounding grid of the plateau mountain railway traction substation provided by the embodiment of the present disclosure will be exemplarily described below with reference to FIGS. 1-2 .

FIG. 1 is a schematic flowchart of a method for constructing a grounding grid of a railway traction substation in plateau mountainous areas according to an embodiment of the present disclosure. Referring to Figure 1, the construction method includes:

S110. Build a soil model of a traction substation with high fill and plateau permafrost, and divide the soil model into at least three soil layers.

Wherein, the at least three soil layers include at least one permafrost layer, at least one fill layer located on the upper side of the permafrost layer, and at least one auxiliary layer located on the lower side of the permafrost layer.

Among them, soil properties, especially soil resistivity, have a direct impact on the grounding resistance of the grounding grid of the traction substation. Exemplarily, the resistivity of the permafrost layer varies greatly in different seasons, the soil resistivity of the fill layer is generally higher, and the soil resistivity of the auxiliary layer under the permafrost layer is generally lower. In this step, the soil model is divided into at least three soil layers to prepare for the laying of ground grids of each layer of the physical grounding grid in the subsequent steps.

Exemplarily, referring to FIG. 2 or FIG. 3, taking the orientation shown in the figure as an example, between the original ground 002 and the flat ground 003 is a fill layer, and the permafrost layer 001 may be located under the original ground 002. The layer is below the permafrost layer 001. This is only an example of the relative relationship of each layer. In an actual application process, each layer may fluctuate according to the actual topography, which is not limited in this embodiment of the present disclosure.

S120. Determine the short-circuit current into the ground of the traction substation.

Among them, this step prepares for the subsequent determination of whether the three-dimensional grounding grid meets the grounding requirements.

Exemplarily, this step can be implemented using a power excitation model. For example, the FSDIST module of the CDEGS software can be used to simulate the external power supply lines of the traction substation, and combined with the short-circuit capacity of the system, the short-circuit current into the ground when the traction substation is short-circuited can be calculated.

In other embodiments, other methods known to those skilled in the art may also be used to determine the short-circuit current to the ground of the traction substation, which is not limited in the embodiments of the present disclosure.

S130. Establish a layered and distributed three-dimensional grounding grid.

The three-dimensional grounding grid 10 includes at least three layers of grounding grids, at least one grounding grid is located on the auxiliary layer, at least one grounding grid is located on the fill layer and serves as the equipment grounding grid, and at least one grounding grid is located on the equipment grounding grid and the auxiliary layer. Between the ground grids in the adjacent layers, the ground grids of the adjacent layers are electrically connected.

Exemplarily, referring to FIG. 2 or FIG. 3, the equipment grounding grid is shown as the top-level grounding grid 13, the grounding grid provided in the auxiliary layer is actually located under the permafrost layer 001, and is shown as the bottom-level grounding grid 11, and the top-level grounding grid is shown. Each layer of ground net between 13 and the bottom ground net 11 can be called the middle ground net 12, and the middle ground net 12 can be optionally set to a single layer according to the thickness of the fill layer in the soil model (as shown in Figure 3). ), double layer (as shown in Figure 2) or multilayer (not shown in the figure); on this basis, by electrically connecting the ground grids of each layer, a "cage" three-dimensional grounding grid 10 with a multi-layer distribution structure is formed. The three-dimensional grounding grid 10 can be constructed according to the terrain, topography and geological characteristics of the plateau mountainous area, and the horizontal space occupied by the three-dimensional structure can be reduced, which is beneficial to reduce the difficulty of constructing the grounding grid in the plateau mountainous area.

S140. Determine whether the three-dimensional grounding grid meets the grounding requirement based on the short-circuit current into the ground and the grounding grid parameters of the three-dimensional grounding grid.

Among them, the three-dimensional grounding grid meets the grounding requirements, which means that it meets the equipment safety and personal safety when a short-circuit fault occurs in the traction transmission. The step may include: verifying various performance indexes of the grounding grid when the grounding grid is short-circuited in the traction station based on the short-circuit current into the ground and the grounding grid parameters of the three-dimensional grounding grid. Specific key performance indicators are exemplarily shown below.

If not, the three-dimensional grounding grid does not meet the grounding requirement, and at this time, S150 is performed.

S150. Adjust the three-dimensional grounding grid until the grounding requirements are met.

So far, a three-dimensional grounding grid that is suitable for plateau and mountainous areas and meets grounding requirements has been formed.

The method for constructing the grounding grid of a railway traction substation in plateau mountainous areas provided by the embodiment of the present invention is to build a soil model based on high fill and plateau permafrost, and divide it into at least a permafrost layer, a fill layer and an auxiliary layer. Three-layer soil layers, a layered and distributed three-dimensional grounding grid is established based on the soil model, and at least one layer of ground grids in the three-dimensional grounding grid is located under the frozen soil layer, and at least one layer of ground grids is used as equipment grounding grids and intermediate grounding grids. The layered ground grid can be set to at least one layer according to the soil thickness in the soil model; then, based on the ground grid parameters of the three-dimensional grounding grid and the short-circuit current into the ground of the traction substation, it is judged whether the three-dimensional grounding grid meets the grounding requirements, and If it is not satisfied, adjust it until it meets the grounding requirements, so that the three-dimensional grounding grid can be adapted to the terrain and geological conditions of the plateau and mountainous areas, and by forming a layered and distributed three-dimensional grounding grid, the vertical grounding grid can be adjusted vertically. The extension of the grounding grid makes up for the problem of the limited horizontal layout area of the grounding grid, so that the grounding grid that meets the grounding requirements can be laid in a limited small area, which reduces the requirements for the environment and reduces the construction difficulty of the grounding grid.

In an embodiment, the dividing the soil model into at least three soil layers in S110 may include: performing equivalent processing on the soil model in horizontal layers, and dividing the soil model into at least three soil layers according to the resistivity of the soil.

Among them, through the equivalent treatment of horizontal stratification, the stratification method of the soil model can be simplified. While this construction method is suitable for the plateau and mountainous area, it is beneficial to reduce the difficulty of constructing the grounding grid.

On this basis, the soil resistivity can be expressed by the average resistivity, minimum resistivity, maximum resistivity or other representative resistivity values of soils with different components in a single layer after horizontal stratification. By dividing the soil resistivity into orders of magnitude intervals, the soil model can be divided into at least three soil layers. For example, adjacent monolayers with a soil resistivity of 10Ω·m are divided into the same soil layer, adjacent monolayers with a resistivity of 100Ω·m are divided into another soil layer, and adjacent monolayers with a resistivity of 1000Ω·m are divided into another soil layer. The single layer is divided into another soil layer, which can be set according to the requirements of the grounding grid of the railway traction substation in the plateau and mountainous areas and the construction method thereof, and the embodiments of the present disclosure will not list them one by one.

In an embodiment, before S110, the method may further include: acquiring a terrain model of high fill and plateau permafrost, and determining the resistivity of soil at each position in the terrain model.

Among them, the terrain model can be established by on-site measurement or by calling local terrain data, and the resistivity of the soil can be obtained through measurement, so as to provide a basis for establishing the soil model.

In one embodiment, S120 may include: calculating a shunt coefficient based on the system short-circuit capacity, grounding resistance, and a model of the external power supply line of the traction substation (also referred to as a "power excitation model") to determine the short-circuit to ground of the traction substation current.

Exemplarily, the external power line model of the traction substation may include power supply incoming line voltage, line length, transmission line tower span, transmission line type, grounding line type, and the like. Based on the above parameters, in the FSDIST module of the CDEGS software, the short-circuit current into the ground of the traction substation can be determined.

In one embodiment, the ground grids of each layer are made of metal conductor material, and the ground grids of adjacent layers are electrically connected by metal conductors.

In this way, engineering methods can be used to construct a three-dimensional grounding grid in terms of structure and shape, and traditional resistance reduction measures such as resistance reducing agents, ion grounding electrodes, and deep well grounding can be avoided to improve the timeliness problem, which is conducive to making the grounding grid long-term and stable. Stable and reliable operation; at the same time, due to the use of conventional metal grounding materials, under the premise of achieving the same effect of grounding, its economy is far superior to the use of resistance reducing agents, ion grounding electrodes or deep well grounding and other resistance reducing measures. That is conducive to reducing costs.

In an embodiment, the method of adjusting the three-dimensional grounding grid in S150 includes at least one of the following: expanding the laying area of at least one layer of grounding grids; increasing the depth of the grounding grids in the auxiliary layer; and increasing the number of layers of grounding grids.

Among them, expanding the laying area of the ground grid can expand the grounding area of the ground grid, which is conducive to improving the grounding effect; increasing the depth of the ground grid in the auxiliary layer is conducive to making the bottom ground grid contact the soil layer with lower resistivity, so as to improve the grounding effect. It is beneficial to improve the grounding effect; increasing the number of layers of the grounding grid is conducive to reducing the overall resistance of the three-dimensional grounding grid and improving the grounding effect. Therefore, by adjusting at least one aspect, the adjusted three-dimensional grounding grid can meet the grounding requirement.

In an embodiment, satisfying the grounding requirement in S150 includes that the grounding resistance, the grounding potential, and the step potential all meet the safety threshold range.

Among them, the grounding resistance needs to be as small as possible, the contact potential and the step potential also need to be as small as possible to meet the equipment safety and personal safety when the traction substation is short-circuited.

Exemplarily, the MALZ module of the CDEGS software can be used to simulate and calculate the three-dimensional grounding grid in combination with the soil model and the power excitation model above to determine whether the above-mentioned indicators meet the safety threshold range.

Exemplarily, the safety threshold ranges of grounding resistance, grounding potential, and step potential can be set according to the requirements of the grounding grid of the traction substation and its construction method, and must meet industry standards, which are neither described nor limited in the embodiments of the present disclosure.

The method for constructing the grounding grid of the railway traction substation in the plateau and mountainous areas provided by the embodiment of the present disclosure can effectively solve the problem of constructing the grounding grid of the traction substation under the terrain and geological conditions of the plateau and mountainous areas, and has the advantages of economical rationality, strong adaptability and The advantage of good long-term stability.

On the basis of the above embodiments, the embodiments of the present disclosure also provide a grounding grid for a railway traction substation in plateau mountainous areas, where the grounding grid can be constructed by any of the construction methods provided in the above embodiments. Therefore, the grounding grid also has the beneficial effects of the construction method in the above-mentioned embodiment, and the similarities can be understood with reference to the explanation of the construction method above, which will not be repeated below.

Exemplarily, FIG. 2 is a schematic structural diagram of a grounding grid of a traction substation in plateau mountains provided by an embodiment of the present disclosure, and FIG. 3 is a schematic structural diagram of another grounding grid of a traction substation in plateau mountainous areas provided by an embodiment of the present disclosure. 2 or 3, the grounding grid includes: a three-dimensional grounding grid 10 composed of at least three layers of grounding grids, and the three-dimensional grounding grid 10 is associated with the soil model 00; wherein, at least one layer of grounding grid The grid is located on the fill layer and serves as an equipment grounding grid, and at least one layer of grounding grids is located between the equipment grounding grid and the grounding grid in the auxiliary layer, and the grounding grids of adjacent layers are electrically connected; the three-dimensional grounding grid meets the grounding requirements.

Exemplarily, FIG. 2 only exemplarily shows that the three-dimensional grounding grid 10 includes four layers of grounding grids, which are the bottom grounding grid 11 , the first intermediate grounding grid 121 , the second intermediate grounding grid 122 and the top grounding grid. 13; Exemplarily, FIG. 3 only exemplarily shows that the three-dimensional grounding grid 10 includes three layers of grounding grids, which are the bottom grounding grid 11, the single-layer intermediate grounding grid 12, and the top grounding grid 13; in other implementations In the method, the number of layers of the grounding grid may also be set according to the requirements of the grounding grid, which is not limited in this embodiment of the present disclosure.

In one embodiment, along the direction in which the auxiliary layer points to the filling layer, the density of the mesh holes of the ground net increases sequentially.

Among them, the density of the mesh holes increases, and the contact area between the ground net and the soil increases, which is conducive to the realization of guiding the electric charge to the ground, thereby helping to improve the grounding effect.

The grounding grid of the traction substation in the plateau and mountainous areas and the construction method thereof provided by the embodiments of the present disclosure, according to the terrain, topography, geology and other characteristics of the plateau and mountain railways, from establishing a soil model to checking the performance indicators of the three-dimensional grounding grid, a set of A complete and effective grounding grid construction method; at the same time, a layered and distributed "cage"-shaped three-dimensional grounding grid structure is proposed, which can meet the characteristics of plateau and mountain railways; thirdly, due to the use of engineering methods, from the structure, Instead of using traditional resistance reducing agents, ion grounding electrodes, deep well grounding and other resistance reduction measures, the entire three-dimensional grounding grid is constructed in shape, which can improve the timeliness problem and is conducive to the long-term, stable and reliable operation of the grounding grid; finally, due to The three-dimensional grounding grid can use conventional grounding materials, and under the premise of achieving the same grounding effect, its economy is far superior to resistance reducing measures such as resistance reducing agents, ion grounding electrodes, and deep well grounding, which is conducive to reducing costs.

The above descriptions are only specific embodiments of the present disclosure, so that those skilled in the art can understand or implement the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (9)

1. A method for constructing a grounding grid of a railway traction substation in a plateau mountain area is characterized by comprising the following steps:

building a soil model of a traction substation with high fill and frozen plateau soil, and dividing the soil model into at least three soil layers; the at least three soil layers comprise at least one frozen soil layer, at least one filling layer positioned on the upper side of the frozen soil layer and at least one auxiliary layer positioned on the lower side of the frozen soil layer;

determining the ground short-circuit current of the traction substation;

establishing a layered and distributed three-dimensional grounding network; the three-dimensional grounding grid comprises at least three layers of grounding grids, wherein at least one layer of grounding grid is positioned on the auxiliary layer, at least one layer of grounding grid is positioned on the filling layer and is used as an equipment grounding grid, at least one layer of grounding grid is positioned between the equipment grounding grid and the grounding grid in the auxiliary layer, and the adjacent layers of grounding grids are electrically connected;

Judging whether the three-dimensional grounding grid meets grounding requirements or not based on the grounding short-circuit current and grounding grid parameters of the three-dimensional grounding grid;

and if not, adjusting the three-dimensional grounding grid until the grounding requirement is met.

2. The method of constructing as claimed in claim 1, wherein dividing the soil model into at least three soil layers comprises:

and performing equivalent treatment on the soil model according to horizontal layering, and dividing the soil model into at least three soil layers according to the resistivity of the soil.

3. The construction method according to claim 2, wherein before building a soil model of a traction power substation with high fill and plateau frozen soil and dividing the soil model into at least three soil layers, the method further comprises:

the method comprises the steps of obtaining a terrain model of high fill and plateau frozen soil, and determining the resistivity of the soil at each position in the terrain model.

4. The construction method according to claim 1, wherein the determining the incoming short circuit current of the traction substation comprises:

and calculating a shunt coefficient based on the system short-circuit capacity, the grounding resistance and the external power supply circuit model of the traction substation, and determining the grounding short-circuit current of the traction substation.

5. The construction method according to claim 1, wherein each layer of the earth screen is made of a metal conductor material, and adjacent layers of the earth screens are electrically connected by the metal conductor.

6. The construction method according to claim 1, wherein the manner of adjusting the stereo grounding grid comprises at least one of:

expanding the laying area of at least one layer of the ground net;

increasing the depth of the counterpoise in the auxiliary layer; and

and increasing the layer number of the ground net.

7. The build method of claim 1, wherein meeting a grounding requirement comprises: the ground resistance, ground potential and step potential all satisfy the safe threshold range.

8. A grounding grid of a railway traction substation in a plateau mountain area, which is constructed by applying the construction method of any one of claims 1 to 7, and comprises:

the three-dimensional grounding grid is formed by at least three layers of grounding grids and is associated with the soil model; wherein, at least one layer of grounding grid is positioned on the auxiliary layer, at least one layer of grounding grid is positioned on the filling layer and is used as an equipment grounding grid, and at least one layer of grounding grid is positioned between the equipment grounding grid and the grounding grid in the auxiliary layer, and the adjacent layers of grounding grids are electrically connected; the three-dimensional grounding grid meets the grounding requirement.

9. A grounding grid as claimed in claim 8, characterized in that the density of the meshes of the grid increases successively in the direction of the auxiliary layer towards the filling layer.

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