CN110398635B - Calculation model of ground resistance - Google Patents

Calculation model of ground resistance Download PDF

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CN110398635B
CN110398635B CN201910650253.6A CN201910650253A CN110398635B CN 110398635 B CN110398635 B CN 110398635B CN 201910650253 A CN201910650253 A CN 201910650253A CN 110398635 B CN110398635 B CN 110398635B
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ground
lead
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CN110398635A (en
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殷勤
熊润
杨文�
赵杰
韩彪
朱文洋
吴培仁
朱洪彬
刘思源
王文文
彭尧尧
王东
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Army Engineering University of PLA
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/146—Measuring arrangements for current not covered by other subgroups of G01R15/14, e.g. using current dividers, shunts, or measuring a voltage drop
    • G01R15/148—Measuring arrangements for current not covered by other subgroups of G01R15/14, e.g. using current dividers, shunts, or measuring a voltage drop involving the measuring of a magnetic field or electric field
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/08—Measuring resistance by measuring both voltage and current
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/20—Measuring earth resistance; Measuring contact resistance, e.g. of earth connections, e.g. plates

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Abstract

The invention discloses a calculation model of a ground resistance. The computational model includes: a convolution perfect matching layer, an ideal conductor layer, a grounding conductor and a lead-up wire; the convolution complete matching layer is used for determining a calculation area, the ideal conductor layer is coated on the convolution complete matching layer, the grounding conductor is arranged in the ground in the calculation area, and the lead-up lead is respectively connected with the grounding conductor and the ideal conductor layer. The invention omits the horizontal connecting wire and the reference conductor, avoids the reflection of the horizontal connecting wire and the reference conductor, ensures that the impact resistance of the grounding conductor can be accurately simulated only by adopting a smaller calculation area, and greatly reduces the calculation resources occupied by the simulation.

Description

Calculation model of ground resistance
Technical Field
The invention belongs to the technical field of simulation algorithms, and particularly relates to a calculation model of a ground resistance.
Background
A traditional calculation model of the grounding resistance is consistent with a test model of the power frequency resistance, and the method is widely applied to grounding system analysis and fine wire approximate precision analysis.
When the finite time domain difference method (FDTD method) is used for analyzing the electromagnetic field problem of the grounding resistor, the smaller the grid size in the FDTD method is, the higher the simulation precision is; it is generally desirable that the mesh size be much smaller than the size of the ground conductors being tested. In the existing calculation model of the ground resistance, a reference conductor and a horizontal connecting line for connecting the reference conductor and a tested ground conductor need to be introduced, and when the resistance of the tested ground conductor is calculated by using the FDTD method, the space of a calculation area is large, so that the grid number of the FDTD method is huge, excessive calculation resources are occupied, and even a common computer cannot perform the calculation work.
Disclosure of Invention
In order to solve the above-described problems of the prior art, it is an object of the present invention to provide a calculation model capable of reducing the ground resistance of a calculation region.
According to an embodiment of the present invention, there is provided a calculation model of a ground resistance, including: a convolution perfect matching layer, an ideal conductor layer, a grounding conductor and a lead-up wire; the convolution complete matching layer is used for cutting off a calculation area, the ideal conductor layer is coated on the convolution complete matching layer, the grounding conductor is arranged in the ground in the calculation area, and the lead-up lead respectively penetrates through the ground, the air and the convolution complete matching layer and is connected with the grounding conductor and the ideal conductor layer.
In an embodiment of the present invention, a first end of the lead-up wire is connected to the ground conductor, and a second end of the lead-up wire passes through the convolution perfect matching layer via air in the calculation region to be connected to the ideal conductor layer.
In an embodiment of the present invention, the ground conductor is in a central symmetrical pattern.
In an embodiment according to the present invention, further, under a cylindrical coordinate system, the impact current i (t) of the ground conductor is expressed by the following equation 1,
[ formula 1]
Figure BDA0002134944730000021
Wherein (i)0,k0) Representing the intersection of the lead-up conductor with the surface of the earth, ar representing the spatial step in the direction r in the cylinder coordinates,
Figure BDA0002134944730000024
in the representation of cylindrical coordinates
Figure BDA0002134944730000022
The strength of the magnetic field in the direction.
In an embodiment according to the present invention, further, under a cylindrical coordinate system, the impulse voltage v (t) of the ground conductor is expressed by the following equation 2,
[ formula 2]
Figure BDA0002134944730000023
Wherein E isr(i,k0) To representRadial electric field strength at the interface of earth and air, NlA coordinate value N on the x-axis in a rectangular coordinate system representing the intersection point of the lead-up wire and the ground surfacekAnd a coordinate value representing the integral path end point on the x-axis in the rectangular coordinate system.
In an embodiment according to the present invention, further the integration path end point is an intersection of the convolution perfect matching layer and the earth surface.
According to another embodiment of the present invention, there is also provided a calculation model of the ground resistance, which does not include the reference conductor and the horizontal connection line.
In another embodiment according to the present invention, further, the calculation model includes: a convolution perfect matching layer, an ideal conductor layer, a grounding conductor and a lead-up wire; the convolution complete matching layer is used for cutting off a calculation area, the ideal conductor layer is coated on the convolution complete matching layer, the grounding conductor is arranged in the ground in the calculation area, and the lead-up lead respectively penetrates through the ground, the air and the convolution complete matching layer and is connected with the grounding conductor and the ideal conductor layer.
In another embodiment according to the present invention, further, a first end of the lead-up wire is connected to the ground conductor, and a second end of the lead-up wire passes through the convolution perfect matching layer via air in the calculation region to be connected to the ideal conductor layer.
In another embodiment according to the present invention, further, the ground conductor is in an axisymmetric pattern.
The invention has the beneficial effects that: the invention omits the horizontal connecting wire and the reference conductor, avoids the reflection of the horizontal connecting wire and the reference conductor, ensures that the impact resistance of the grounding conductor can be accurately simulated only by adopting a smaller calculation area, and greatly reduces the calculation resources occupied by the simulation.
Drawings
The above and other aspects, features and advantages of embodiments of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:
FIG. 1 shows an architecture diagram of a prior art computational model of ground resistance;
FIG. 2 shows a schematic diagram of Ampere Loop Law as applied to an FDTD unit containing a riser conductor;
FIG. 3 shows an architecture diagram of a computational model of ground resistance according to an embodiment of the invention;
FIG. 4 is a schematic diagram of a computational model of ground resistance in column coordinates according to an embodiment of the invention;
FIG. 5 is a graph comparing the impulse resistance calculated by a prior art calculation model and the impulse resistance calculated by a calculation model according to an embodiment of the present invention.
Detailed Description
Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the specific embodiments set forth herein. Rather, these embodiments are provided to explain the principles of the invention and its practical application to thereby enable others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated.
First, a calculation model of a ground resistance according to the related art will be described in detail below in order to compare with a calculation model of a ground resistance according to an example of the present invention. The calculation of the impulse voltage (or transient voltage) and the impulse current (or transient current) of the grounding conductor is mainly described in detail. It will be appreciated that after the surge voltage and the surge current are calculated, the corresponding surge resistance (i.e. the impulse grounding resistance) can be calculated, i.e. the surge resistance is equal to the surge voltage divided by the surge current.
Fig. 1 shows an architecture diagram of a prior art calculation model of ground resistance.
Referring to fig. 1, the convolution perfect matching layer 50 defines a calculation area a for performing a shock resistance (i.e., a shock ground resistance) simulation calculation. It should be noted that in the description of the prior art, the earth, the ground, the air, etc. are all located within the calculation area a, unless particular emphasis is of course given.
Further, the ground conductor 10, the lead-up wire 20, the reference conductor 30, and the horizontal connecting wire 40 are all located in the calculation region a, and of course, the ground conductor 10 and the reference conductor 30 are all disposed in the ground. One end of the up lead 20 is connected to the ground conductor 10 while the other end of the up lead 20 is led out to the ground and connected to the reference conductor 30 through the horizontal connection line 40. The reference conductor 30 is used to return the current to ground.
Continuing with reference to FIG. 1, LcRepresents the length of the horizontal connection line 40, i.e., the distance between the reference conductor 30 and the lead-up wire 20; hcRepresents the height of the horizontal connecting line 40 from the ground; l isiRepresenting the length of the integration path when calculating the surge voltage; l isrIndicating the length of reference conductor 30 into the earth. Here, in the calculation simulation, in order to inject a current into the calculation model to generate an electric field and a magnetic field, an excitation source 60 may be connected to the lead wire 20. And in FIG. 1, HsIt means the height of the injection of the excitation source 60, i.e., the height from the ground of the connection point of the excitation source 60 and the lead-up wire 20. Here, a lightning strike back current is selected as the excitation source 60, which may be expressed as equation 1 below.
Iin(t)＝I0(e-αt-e-βt) (1)
Wherein, I0＝109405V/m，α＝22708s-1，β＝1294530s-1。
The calculation process of the impulse voltage v (t) and the impulse current i (t) of the grounded conductive body 10 will be described in detail with reference to fig. 1 and 2. In the following calculation, the ground is assumed to be a uniform ground, and the ground is assumed to have constant constitutive parameters.
<Impulse voltage>
The surge voltage (or transient voltage) v (t) of the ground conductor 10 is the difference between the potential of the lead-up wire 20 and the potential at infinity, and the surge voltage of the ground conductor 10 is expressed by the following equation 2.
Figure BDA0002134944730000041
Here, NlShowing the intersection of the lead-up conductor 20 with the ground. That is, in equation 2, the electric field strength is integrated up to infinity from the intersection of the upper conductor 20 and the ground.
In the FDTD analysis, a voltage across one Yee grid of the FDTD may be defined as the following equation 3.
Vj＝Ej·Δsj (3)
The impulse voltage v (t) is effectively approximated by integrating the electric field strength along the interface of air and ground from the riser wire 20 (i.e., the intersection of the riser wire 20 and ground) to the boundary of the calculation region (point K in fig. 1). Combining equation 2 and equation 3, the surge voltage v (t) is finally expressed as equation 4 below.
Figure BDA0002134944730000042
Here, EjRepresenting the electric field strength component, Δ s, of the interface of air and groundjIs the grid size, NKIs the grid number of the K points in fig. 1.
<Rush current>
Fig. 2 shows a schematic diagram of the application of ampere-loop law to an FDTD grid surrounding a riser conductor.
Referring to fig. 2, the rush current (or transient current) i (t) of the grounded conductor 10 is obtained by integrating the boundary magnetic field along the four FDTD grids including the riser wire 20, i.e., using a square integration path shown by a dotted line in fig. 2. However, the magnetic field strength varies with distance from the wire. That is, the magnetic field strength varies from different locations on the riser wire 20. For example, the distance of the integration path to the lead-up conductor 20 is from
Figure BDA0002134944730000051
A ofxChange of/2 to
Figure BDA0002134944730000052
Of
Figure BDA0002134944730000053
Means that
Figure BDA0002134944730000057
Magnetic field intensity H ofxIs that
Figure BDA0002134944730000054
Intensity of magnetic field HxIs/are as follows
Figure BDA0002134944730000055
Wherein Δ ═ Δx＝ΔzAnd Δ is the FDTD grid size.
Here, the rush current i (t) of the ground conductive body 10 is derived from the integral of the magnetic field strength in an ampere loop with a radius (half of the mesh size) of Δ/2, and the rush current i (t) can be expressed as the following equation 5.
I(t)＝πΔHΔ/2 (5)
Further, a circular ampere loop may be utilized instead of a square ampere loop. The magnetic field strength component along the circular integral path of radius a/2 is fixed. In this way, the rush current i (t) of the ground conductor 10 can be simulated more accurately.
Further, the magnetic field intensity component H in the above equation 5Δ/2Approximately equal to the weighted average of the magnetic field strength at four nodes each at a distance of delta/2 from the lead-up conductor 20, and hence the magnetic field strength component HΔ/2Can be expressed as the following equation 6, wherein (i)0,j0,k0) Is the intersection of the lead-up conductor 20 with the ground.
Figure BDA0002134944730000056
Further, the above equation 6 is brought into the above equation 5 to obtain the following equation 7, that is, the impact current i (t) of the ground conductor 10 can be finally expressed as the following equation 7.
Figure BDA0002134944730000061
As described in the background art, since the reference conductor 30 and the horizontal connecting line 40 are introduced into the calculation model shown in fig. 1, the area of the calculation region a is large, which makes the number of grids very large when calculating by using the FDTD method, and has the disadvantage of occupying too much calculation resources, even making an ordinary computer unable to work. Here, in FIG. 1, LiShould be not less than 20m, LcShould be not less than 30m, LrShould be no less than 3 m. When H is presentcThe height is 0.9m, the length of the ground conductor 10 is 5m, the distance between the horizontal connection line 40 and the convolution perfect matching layer 50 is 0.6m, and the size of the entire calculation area a calculated using the calculation model shown in fig. 1 is 73m × 43m × 10.1m considering the thickness of the convolution perfect matching layer 50 as 10 layers and the grid size as 0.15 m.
Hereinafter, a calculation model of the ground resistance according to an embodiment of the present invention will be described in detail, in which the calculation of the impulse voltage (or referred to as transient voltage) and the impulse current (or referred to as transient current) of the ground conductor is mainly described in detail. It will be appreciated that after the surge voltage and the surge current are calculated, the corresponding surge resistance (i.e. the impulse grounding resistance) can be calculated, i.e. the surge resistance is equal to the surge voltage divided by the surge current.
Fig. 3 shows an architecture diagram of a computational model of the ground resistance according to an embodiment of the invention.
Referring to fig. 3, in the embodiment according to the present invention, the convolution perfect matching layer 100 defines a calculation region B for performing a shock resistance (i.e., a shock ground resistance) simulation calculation. It should be noted that in the description of the embodiments according to the invention, the earth, the ground, the air, etc. are located within the calculation region B, unless of course particular emphasis is placed.
Further, the ground conductor 200 and the lead-up wire 300 are both located in the calculation region B, and the ground conductor 10 is naturally disposed in the ground. The ideal conductor layer 400 is wrapped over the convoluted perfect matching layer 100 and further, the ideal conductor layer 400 is wrapped over the outer surface of the convoluted perfect matching layer 100.
The resistance of the ideal conductor layer 400 is 0, i.e., the conductivity is infinite. Ideally, the conductor layer 400 has no electric and magnetic fields within it and no tangential electric and normal magnetic fields on its surface. Since there is no electromagnetic field in the ideal conductor layer 400, the electromagnetic field is totally reflected when it is incident on the ideal conductor layer 400, and thus no electromagnetic energy enters the ideal conductor layer 400, and the energy density of the reflected wave is equal to that of the incident wave.
Further, the first end of the lead-up wire 300 is brought into the ground to be connected to the ground conductor 200. To provide a return path for the injected current, the second end of the up conductor 300 is brought out of ground and through the convoluted perfect matching layer 100 via air to connect with the ideal conductor layer 400. This corresponds to the introduction of a virtual reference conductor through which the excitation current flows back into the ground. Compared to the prior art computational model shown in FIG. 1, the computational model according to embodiments of the present invention has substantially reduced discontinuities and, thus, substantially reduced reflections; and the emulation area can be greatly reduced due to the removal of the reference conductor. When calculating the impulse grounding resistance by using the calculation model according to the embodiment of the present invention, the definition of the impulse voltage, the impulse current and the impulse grounding resistance is exactly the same as that of the calculation model of the prior art.
Continuing with FIG. 3, hcRepresenting the distance between the convolutional perfect matching layer 100 and the ground. Here, in the calculation simulation, in order to inject a current into the calculation model to generate an electric field and a magnetic field, an excitation source 500 may be connected to the lead wire 300. While in FIG. 3, hsIt means the injection height of the excitation source 500, i.e., the distance between the connection point of the excitation source 500 and the lead-up wire 300 and the ground. Here, as shown in FIG. 1, the lightning strike-back is selectedThe current is used as the excitation source 500, and the injected current is represented by the above equation 1, which is not described herein.
The following is a validation process of a computational model according to an embodiment of the invention.
When calculating the impulse grounding resistance within 2 mus by using the calculation model of the prior art, if the distance L between the reference conductor 30 and the lead-up wire 20 is consideredcIs large enough (L)cNot less than 300m) and the height H of the horizontal connecting line 40cIs sufficiently high (H)c≧ 300m), since the reflection of the reference conductor 30 and the horizontal connection line 40 has not yet arrived before the end of the simulation, the impulse grounding resistance at this time can be regarded as the reference impulse grounding resistance of the grounding conductor 10. To verify the validity of the calculation model according to the embodiment of the present invention, the impulse grounding resistance calculated by the calculation model according to the embodiment of the present invention is compared with the calculation model L of the prior artc300m and HcThe impulse grounding resistance at 300m was compared.
Here, the impulse grounding resistance was calculated when a single round steel with a radius of 5cm was used as a grounding conductor. In the calculation, the FDTD space step length in the two calculation models is delta-deltax＝Δy＝Δz0.5m, the time step is defined bytObtained as Δ/2 c. The calculation time length of both calculation models is 2 mus, and the impulse grounding resistance is shown in figure 5. As can be seen from fig. 5, the impulse grounding resistance calculated by the calculation model according to the embodiment of the present invention is identical to the reference impulse grounding resistance, that is, the impulse grounding resistance calculated by the two calculation models is identical for the same grounding conductor, thereby proving the effectiveness of the calculation model according to the embodiment of the present invention.
The computational area of the computational model according to an embodiment of the invention in plane xoz is 30m 20m, whereas the prior art computational model shown in fig. 1 is 330m 20m, i.e. the computational model of an embodiment of the invention occupies less than 10% of the computational area of the prior art computational model, i.e. the computational area B is less than 10% of the computational area a. The computational model according to the embodiment of the invention takes 21 seconds to compute and the prior art computational model takes more than 330 seconds, i.e. the computational model according to the embodiment of the invention takes only 6% of the prior art computational model. Therefore, the computational model according to the embodiment of the present invention can greatly reduce the computational resources occupied by numerical simulation compared to the prior art computational model.
Furthermore, another exemplary advantage of the computational model according to embodiments of the invention is that: due to its symmetry in the xoz plane, the calculation region B can be further reduced when dealing with symmetrical ground conductors. When the ground conductor of flat or square steel is simulated using the calculation type according to the embodiment of the present invention, the entire calculation area can be reduced to 1/4 of the calculation area of the calculation model of the prior art; when a circular grounding conductor is simulated by using the calculation model according to the embodiment of the invention, the calculation model can be further simplified into a two-dimensional calculation problem due to the axisymmetric characteristic (namely, the grounding conductor is axisymmetric with respect to the straight line where the lead-up conductor is located).
The calculation process of the surge voltage v (t) and the surge current i (t) of the grounding conductor 200, which is axisymmetric with respect to the straight line on which the lead-up wire is located, will be described in detail with reference to fig. 3 and 4. In the following calculation process, it is assumed that the ground is a uniform ground, and that the ground has a constant constitutive parameter (constitutive parameter).
In the two-dimensional cylindrical coordinates, iterative formulas of electric field intensity in the r direction and the z direction in the cylindrical coordinates are expressed as the following equations 8 and 9.
Figure BDA0002134944730000081
Figure BDA0002134944730000082
Further, in cylindrical coordinates, along cylindrical coordinates
Figure BDA0002134944730000083
The iterative formula of the magnetic field strength of the direction is expressed as the following formulaAnd (5) a seed 10.
Figure BDA0002134944730000084
In the above equations 8, 9 and 10, i, k are respectively the r-direction and z-direction progressive coefficients in the cylindrical coordinates, n is the time progressive coefficient, Δ z and Δ r are respectively the z-direction and r-direction spatial step length in the cylindrical coordinates, Δ t is the time step length, and σ t is the time step lengthgFor earth conductivity,. epsilon0Is the dielectric constant of air, epsilonrgIs the dielectric constant of earth with respect to air,
Figure BDA0002134944730000091
in cylindrical coordinates
Figure BDA0002134944730000092
Strength of the directional magnetic field, ErAnd EzThe electric field strengths in the r-direction and the z-direction in the cylindrical coordinates, respectively.
Through iterative calculation of the equations 8 to 10, the electric field strength and the magnetic field strength at each time (n Δ t) can be obtained, and then the voltage and the current at the corresponding time can be obtained through integration with the corresponding space step length.
Fig. 4 is a schematic diagram of a calculation model of the ground resistance in the cylindrical coordinates according to an embodiment of the present invention.
Referring to fig. 3 and 4, the rush current i (t) of the ground conductive body 200 according to the ampere-loop law may be expressed as the following equation 11.
Figure BDA0002134944730000093
Wherein (i)0,k0) Is the intersection of the lead-up conductor 300 and the ground,
Figure BDA0002134944730000094
Δ r is the radius of the integration loop of the inrush current I (t). In the formula 10
Figure BDA0002134944730000095
Is replaced by
Figure BDA0002134944730000096
And in the formula 10
Figure BDA0002134944730000097
Is replaced by
Figure BDA0002134944730000098
Thereby can obtain
Figure BDA0002134944730000099
By an iterative formula of
Figure BDA00021349447300000910
The magnetic field intensity at each moment can be obtained by iterative calculation of the iterative formula.
The surge voltage (or transient voltage) v (t) of the ground conductor 200 is the difference of the transient potential from the upper lead 300 to an infinite distance, and the surge voltage of the ground conductor 200 can be expressed as the following equation 12.
Figure BDA00021349447300000911
Er(i',k0) Representing the radial electric field strength, N, at the interface of earth and airlDenotes the coordinate on the x-axis of the intersection of the lead-up wire 300 and the ground, NkThe coordinates of the end point of the integration path (point K in fig. 3 and 4, one of the intersections of the inner surface of the convolution perfect matching layer 100 with the earth's surface) on the x-axis are represented. Will be in formula 8
Figure BDA00021349447300000912
Replace by i', and replace k in equation 10 by k0Thus, E can be obtainedr(i′,k0) By an iterative formula of Er(i′,k0) Each of the iterative formulas can be obtained by iterative calculationRadial electric field strength at each instant.
Due to the fact that the two-dimensional calculation region is adopted, the whole process of high-resolution FDTD simulation can be conducted, the electromagnetic field near the grounding conductor can be simulated accurately, and more accurate response of the grounding conductor is obtained.
In summary, according to the embodiments of the present invention, the virtual reference electrode is introduced, and the horizontal connection line and the reference conductor are omitted, so that reflection of the horizontal connection line and the reference conductor is avoided, and the impulse resistance of the ground conductor can be accurately simulated only by using a smaller calculation area, thereby greatly reducing calculation resources occupied by simulation. When the grounding conductor is in an axisymmetric pattern, the calculation process can be simplified to be carried out under a two-dimensional cylindrical coordinate (as shown in fig. 4), the calculation area can be further reduced, and the calculation resources are greatly saved.
While the invention has been shown and described with reference to certain embodiments, those skilled in the art will understand that: various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.

Claims (8)

1. A computational model of ground resistance, the computational model comprising: a convolution perfect matching layer, an ideal conductor layer, a grounding conductor and a lead-up wire; the convolution complete matching layer is used for determining a calculation area, the ideal conductor layer is coated on the convolution complete matching layer, the grounding conductor is arranged in the ground in the calculation area, and the lead-up lead is respectively connected with the grounding conductor and the ideal conductor layer;
a first end of the lead-up wire is connected to the ground conductor, and a second end of the lead-up wire passes through the convolution perfect matching layer via air within the calculation region to connect with the ideal conductor layer.
2. The computational model of claim 1, wherein the ground model is in an axisymmetric pattern.
3. The calculation model according to claim 1 or 2, characterized in that the impulse current I (t) of the ground conductor is expressed by the following equation 1 in a cylindrical coordinate system,
[ formula 1]
Figure FDA0003125404640000011
Wherein (i)0,k0) Representing the intersection of the lead-up conductor with the surface of the earth, ar representing the spatial step in the direction r in the cylinder coordinates,
Figure FDA0003125404640000014
in the representation of cylindrical coordinates
Figure FDA0003125404640000012
The strength of the magnetic field in the direction.
4. The calculation model according to claim 3, characterized in that the impulse voltage V (t) of the ground conductor is expressed as the following equation 2 in a cylindrical coordinate system,
[ formula 2]
Figure FDA0003125404640000013
Wherein E isr(i,k0) Representing the radial electric field strength, N, at the interface of earth and airlA coordinate value N on the x-axis in a rectangular coordinate system representing the intersection point of the lead-up wire and the ground surfacekAnd a coordinate value representing the integral path end point on the x-axis in the rectangular coordinate system.
5. The computational model of claim 4, wherein the integration path endpoint is an intersection of the convolution perfect match layer and the earth's surface.
6. A computational model of ground resistance, characterized in that it does not comprise a reference conductor and a horizontal connecting line, and in that it comprises: a convolution perfect matching layer, an ideal conductor layer, a grounding conductor and a lead-up wire; the convolution complete matching layer is used for determining a calculation area, the ideal conductor layer is coated on the convolution complete matching layer, the grounding conductor is arranged in the ground in the calculation area, and the lead-up lead is respectively connected with the grounding conductor and the ideal conductor layer.
7. The computational model of claim 6, wherein a first end of the lead-up wire is connected to the ground conductor and a second end of the lead-up wire is passed through the convolution perfect matching layer via air within the computational region to connect to the ideal conductor layer.
8. The computational model of claim 7, wherein the ground conduction model is in an axisymmetric pattern.
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Citations (4)

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