A method for calculating the grounding resistance of a horizontally laid rectangular grounding body

Abstract

The present invention discloses a method for calculating the grounding resistance of a horizontally laid rectangular grounding body, belongs to the technical field of calculating high soil resistivity, and solves the problem that the resistivity of the grounding resistance cannot be calculated in high soil areas. The grounding device of the present invention comprises a rectangular panel, and the rectangular panel is placed and laid at a depth of 0.7m from the horizontal ground; the electric potential between the rectangular panel and any point parallel to the ground can be accurately calculated through a calculation formula; the present invention calculates the grounding resistance by transitioning from the rectangular panel to the ground soil current density, and can specifically calculate the grounding resistance value between the rectangular panel and the ground in the high soil area, thereby realizing the accurate calculation of the grounding resistance of the rectangular panel. The present invention has the advantage of solving the calculation method of the resistivity in the high soil area.

Description

Technical Field

[0001] The invention relates to the technical field of calculating high soil resistivity, and in particular to a method for calculating the grounding resistance of a horizontally laid rectangular parallelepiped grounding body. Background Art

[0002] With the rapid development of my country's economy, the power industry has entered a period of rapid development. However, the rapid economic development has also brought about an extreme shortage of land resources. The site selection of substations has become increasingly difficult, and the problem of high soil resistivity often occurs. At the same time, due to the large-scale promotion of GIS or HGIS distribution devices, the site area of ​​substations has been further reduced. The two have caused the problem of excessive grounding resistance in substations to be more common (the grounding resistance is specified to be ≤0.5Ω), and high grounding resistance can easily cause harm to substation operators and damage to equipment. Therefore, reducing grounding resistance is an important guarantee to ensure the safety of substation personnel and equipment.

[0003] Due to geographical restrictions, some substations have to be built in areas with high soil resistivity, which results in the design and calculation values ​​of grounding resistance, step voltage and contact voltage of these substations being too high and unable to meet the requirements of current standards. Therefore, it is one of the key points of substation electrical design and construction to reasonably determine the design of the grounding device and calculate the grounding resistance. Summary of the invention

[0004] The purpose of the present invention is to solve the technical problem that the resistivity of the grounding resistance cannot be calculated in high soil areas. The present invention provides a method for calculating the grounding resistance of a horizontally laid rectangular grounding body.

[0005] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions:

[0006] A method for calculating the grounding resistance of a horizontally laid rectangular parallelepiped grounding body comprises the following steps:

[0007] Step 1): Set basic parameters: Establish a 0-xyz coordinate system based on a uniformly charged rectangular panel. The origin of the coordinate system is a corner of the uniformly charged rectangular panel. The X axis is the length direction of the uniformly charged rectangular panel, the Y axis is the width direction of the uniformly charged rectangular panel, and the Z axis is the vertical direction of the uniformly charged rectangular panel. Set the coordinates of a point p in the coordinate system space to p(x0, y0, z0), set any differential point on the uniformly charged rectangular panel to ds=dxdy, the coordinates of the differential point are (x, y), and the longest differential diameter is the distance from the farthest point on the differential point to the origin;

[0008] Step 2): Calculate the differential potential generated by the rectangular panel to the space point P you , you The calculation formula is as follows (1):

[0009]

[0010] Wherein, 0≤x≤a, a is the length of the uniformly charged rectangular panel, 0≤y≤b, b is the width of the uniformly charged rectangular panel;

[0011] Step 3): Integrate the differential potential dU to obtain the potential U generated at point P. Formula (2) is as follows:

[0012]

[0013] Further deduction leads to the following formula (3). According to the formula (3), the potential U generated by any point p (x0, y0, z0) in the space coordinate system 0-xyz established by the rectangular panel is the following formula (6):

[0014]

[0015]

[0016] Step 4): Calculate the grounding resistance R using the formula (6) and the following current calculation formula (7), and the obtained formula (8) for the grounding resistance R is as follows:

[0017] The current calculation formula (7) is: I = Q × S = Q × a × b

[0018]

[0019] The beneficial effects of the present invention are as follows:

[0020] 1. The present invention reduces the grounding resistance by reducing the panel current density that transitions from the grounding panel to the soil. The new calculation method can specifically calculate the grounding resistance value of the grounding device using a rectangular panel in the area with high soil resistivity, thereby realizing the accurate calculation of the resistance of the panel grounding body, thereby fundamentally solving the problem of calculating the complex grounding resistance in the area with high soil resistivity.

[0021] 2. The present invention fundamentally improves the calculation and grounding costs in areas with high soil resistivity, reduces accidents, improves the utilization rate of equipment and has a simple structure.

[0022] 3. The present invention is conducive to the safe operation of the grounding resistor, and the safe and reliable voltage will not cause harm to people.

[0023] 4. The present invention occupies a small area, which can be ignored, and uses a small amount of steel. It can be laid in both complex outdoor areas and cities.

[0024] 5. The present invention is not only applicable to the grounding resistance under impulse current, but also applicable to the grounding resistance under power frequency current, and provides a calculation basis for solving the step voltage calculation.

[0025] 6. The present invention can calculate the resistivity of high soil resistance areas by burying the rectangular panels 0.7 m underground and laying the rectangular panels parallel to the ground. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the calculation of the potential at point P of the present invention.

[0027] Reference numerals: 1 - rectangular panel. DETAILED DESCRIPTION

[0028] In order for those skilled in the art to better understand the present invention, the present invention is further described in detail in the following embodiments. In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0029] Example 1

[0030] like Figure 1 As shown, this embodiment provides a device for calculating the grounding resistance of a horizontally laid rectangular grounding body, including a rectangular panel 1. The size of the rectangular panel 1 is calculated based on local installation and geological conditions. The rectangular panel 1 is horizontally laid and buried in the ground. For protection and safety, the plane of the rectangular panel 1 is buried at a depth of about 0.7m from the ground during burial. The burial depth is related to local installation and geological conditions.

[0031] Example 2

[0032] Based on the above-mentioned device for calculating the grounding resistance of a horizontally laid rectangular grounding body, this embodiment also discloses a method for calculating the grounding resistance (rectangular panel resistance) of a horizontally laid rectangular grounding body, including the following steps:

[0033] like Figure 1As shown, step 1): set basic parameters: establish a 0-xyz coordinate system based on the uniformly charged rectangular panel 1, the origin of the coordinate system is a corner of the uniformly charged rectangular panel 1, the X-axis is the length direction of the uniformly charged rectangular panel 1, the Y-axis is the width direction of the uniformly charged rectangular panel, and the Z-axis is the vertical direction of the uniformly charged rectangular panel. Set the coordinates of a point p in the coordinate system space to p(x0, y0, z0), set any differential point on the uniformly charged rectangular panel to ds=dxdy, the coordinates of the differential point are (x, y), the longest differential diameter is the distance from the farthest point on the differential point to the origin, such as: the distance from the coordinate (0, y) to the origin is y, the distance from the coordinate (x, 0) to the origin is x, and the distance from the coordinate (x, y) to the origin is

[0034] Step 2): Calculate the differential potential generated by the rectangular panel 1 on the spatial point P you , you The calculation formula is as follows (1):

[0035]

[0036] Wherein, 0≤x≤a, a is the length of the uniformly charged rectangular panel, 0≤y≤b, b is the width of the uniformly charged rectangular panel;

[0037] Step 3): Integrate the differential potential dU to obtain the potential U generated at point P, as shown in the following formula (2):

[0038]

[0039] Further deduction leads to formula (3) as follows:

[0040]

[0041] Among them, formula (3) is decomposed into two parts, ① and ②. Part ② is the part of part ① when a=0. Let The following further explains part ① in formula (3) to obtain formula (4):

[0042]

[0043] Let (a-x0) 2 +z0 2 =β 2 Substituting the parameter β into the formula, we get

[0044]

[0045] Let y-y0=βtgα (β is the parameter to be substituted into the formula)

[0046]

[0047] Let

[0048] Let Substituting into formula (4) gives the following formula (5):

[0049]

[0050]

[0051] The part ③ in formula (5) can be obtained, that is:

[0052] Let

[0053]

[0054] Let

[0055]

[0056] Without loss of generality, let

[0057]

[0058] Let

[0059]

[0060] Then the part ① in formula (3) for the above formula (5) is

[0061]

[0062] Among them,

[0063] Formula (5) is derived from formula (3). The above part ② in formula (3) is the formula part when the parameter a = 0 of the part ① in formula (3);

[0064] Therefore, the part ② in formula (3) is

[0065]

[0066] Finally, the electric potential generated by an arbitrary point p(x0, y0, z0) in space in the space coordinate system 0-xyz established with the rectangular panel 1 is: U = ① - ② to obtain formula (6). Let b < y0; U is the electric potential of an arbitrary point outside the rectangular panel 1, that is, the electric potential of an arbitrary point between the rectangular panel 1 and the ground.

[0067]

[0068] Here,

[0069] Let b>y0, b=y0 and U can be calculated by the same logic.

[0070] Step 3): Calculate the grounding resistance R using the formula (6) and the following current calculation formula (7), and obtain the formula (8) of the grounding resistance R as follows:

[0071]

[0072] Current calculation formula (7): I = Q × S = Q × a × b, formula (6) divided by formula (7) to obtain the following formula (8):

[0073]

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The patent protection scope of the present invention shall be based on the claims. All equivalent changes made using the contents of the description of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for calculating the grounding resistance of a horizontally laid rectangular grounding body, characterized in that: The following steps are involved: Step 1): Set basic parameters: Establish a 0-xyz coordinate system based on a uniformly charged rectangular panel. The origin of the coordinate system is a corner of the uniformly charged rectangular panel, the X axis is the length direction of the uniformly charged rectangular panel, the Y axis is the width direction of the uniformly charged rectangular panel, and the Z axis is the vertical direction of the uniformly charged rectangular panel. Set the coordinates of a point p in the coordinate system space to p(x0, y0, z0), set any differential point on the uniformly charged rectangular panel to ds=dxdy, the coordinates of the differential point are (x, y), and the longest differential diameter is the distance from the farthest point on the differential point to the origin; Step 2): Calculate the differential potential dU generated by the rectangular panel to the spatial point P. The calculation formula for dU is as follows: in, , a is the length of the uniformly charged rectangular panel, , b is the width of the uniformly charged rectangular panel; Step 3): Integrate the differential potential dU to obtain the potential U generated at point P, the formula is as follows: , further deduced, the formula is as follows: According to the above formula, the potential U generated by any point p (x0, y0, z0) in the space coordinate system 0-xyz established by the rectangular panel is as follows: Step 4): Calculate the grounding resistance R using the above formula and the following current calculation formula. The formula for the grounding resistance R is as follows: The current calculation formula is: 。

Images