Soil resistivity measurement method and detection device

Abstract

The invention discloses a soil resistivity measurement method and a detection device, and relates to the technical field of soil resistivity measurement, the soil resistivity detection device comprises a voltage detection unit and a constant current source unit capable of adjusting frequency, one end of the constant current source unit is connected with a tower through a metal clamp, and the other end of the constant current source unit is connected with an auxiliary ground pole; the voltage detection unit is used for measuring the voltage of the constant current source; according to the invention, the soil resistivity detection device, the auxiliary earth pole and the grounding body are adopted to measure the soil resistivity, the grounding pole of the power transmission line tower is fully utilized, and high-precision measurement of the soil resistivity is realized at the power transmission line tower; according to the invention, the soil resistivity of the power transmission line tower can be accurately measured, on one hand, on-site measurement can be facilitated without being influenced by a measurement environment, and on the other hand, the influence of contact resistance can be well eliminated.

Description

Technical Field

[0001] The present invention relates to the technical field of soil resistivity measurement, in particular to a soil resistivity measurement method and detection device. Background Art

[0002] Transmission towers are a crucial component of power transmission lines. Once a lightning incident occurs on a transmission tower, it can pose a serious threat to nearby lives, paralyzing my country's power transmission lines and impacting the lives of citizens. Therefore, research on the lightning protection reliability of transmission towers is crucial. Soil resistivity is crucial for research on the lightning protection reliability of transmission towers, and is also crucial for research on lightning protection technology for transmission lines and practical engineering. Research on the lightning protection reliability of transmission towers must begin with soil resistivity. Relevant research has shown that soil resistivity plays a key role in this research, and relevant standards have proposed different tower grounding resistance requirements for different soil resistivity environments. Soil resistivity is affected by many factors, including soil moisture content, soil type, soil salinity, and temperature, and requires certain corrections.

[0003] Currently, the main methods for measuring soil resistivity include the four-electrode method, the Wenner line method, and the Schlumberger method. However, the existing measurement methods all have strict precautions during the measurement process, such as the placement, spacing, and penetration depth of the electrodes. The penetration depth of the electrodes should not exceed 1 / 20 of the electrode spacing to avoid interference from underground metal objects. In addition, the measurement is greatly affected by the environment. The measurement needs to be carried out in the dry season or after several days of clear weather, and requires an open area, otherwise it will affect the measurement accuracy. However, the conditions for accurate measurement are not available around the towers. Therefore, the existing methods cannot accurately measure the soil resistivity of transmission line towers. Summary of the Invention

[0004] To solve the above problems, the purpose of the present invention is to provide a soil resistivity measurement method and detection device, which can accurately measure the soil resistivity of transmission line towers. The measurement accuracy is not affected by the environment, and provides data support and technical guarantee for the evaluation of the lightning protection and grounding performance of transmission line towers.

[0005] To achieve the above-mentioned purpose, the present invention is implemented through the following technical solutions:

[0006] A soil resistivity detection device includes a voltage detection unit and a constant current source unit capable of adjusting frequency. One end of the constant current source unit is connected to a pole tower via a metal clip, and the other end is connected to an auxiliary ground electrode. The voltage detection unit is used to measure the voltage of the constant current source.

[0007] Preferably, the frequency of the constant current source unit is 0-20 kHz.

[0008] Preferably, the auxiliary ground electrode is made of galvanized round steel.

[0009] Preferably, the auxiliary ground electrode has a length of 0.1 to 1 m and a diameter of 5 to 20 mm.

[0010] The present invention also includes a soil resistivity measurement method, which uses a soil resistivity detection device, an auxiliary ground electrode and a grounding body to measure the soil resistivity. The grounding body and the tower adopt a square plus radial grounding form.

[0011] Preferably, the auxiliary ground pole is driven into the center point O of the four-corner tower, and the buried depth is equal to the length, both of which are p.

[0012] Preferably, the area center point O of the four-corner tower is calculated according to the following steps:

[0013] Suppose the four endpoints of the four-corner tower are A, B, C, and D, and determine the midpoints E, F, G, and H of AB, CD, AD, and BC respectively. Connect EF and GH, and their intersection O is the center of the area.

[0014] Preferably, the steps include:

[0015] S1, specify the parameters of the auxiliary pole, specifically the length p and the diameter m of the auxiliary pole;

[0016] S2, clarify the relevant parameters of the tower and grounding body, specifically the radial length l1, the distance between adjacent tower feet l2, the burial depth h, and the grounding body diameter d;

[0017] S3, drive the auxiliary ground pole into the ground at the center point O of the four-corner tower, and the buried depth and length of the auxiliary ground pole are equal, both are p;

[0018] S4, tightly connect the two ends of the soil resistivity detection device to the tower and the auxiliary ground electrode respectively, turn on the soil resistivity detection device, inject 20mA current into the auxiliary ground electrode, and detect the voltage value at both ends of the soil resistivity detection device;

[0019] S5, gradually increase the frequency, when the measured voltage value no longer changes, record the voltage value U, and use the formula Calculate the resistance between two points;

[0020] S6, using formula Calculate soil resistivity.

[0021] Preferably, the length of the radiation line in the grounding body is 1 to 10 m, and the burial depth is 1 to 5 m.

[0022] Preferably, the diameter of the grounding body is 5 to 20 mm.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The soil resistivity measurement method of the present invention can accurately measure the soil resistivity of a transmission line tower. On the one hand, it is convenient for on-site measurement and is not affected by the measurement environment. On the other hand, it can better eliminate the influence of contact resistance.

[0025] A soil resistivity measurement method of the present invention fully utilizes the grounding electrode of a transmission line tower to achieve high-precision soil resistivity measurement at the transmission line tower. Auxiliary electrodes are arranged at the center points of the four corners of the tower. Current is injected using an AC constant current source through a soil resistivity detection device of the present invention. The frequency is 20 kHz and the current value is 20 mA. High-frequency measurement is adopted to avoid the shunting effect of the overhead ground wire. Moreover, since the voltage detection circuit has a high input resistance, its shunting effect on the constant current source can be ignored, thereby further ensuring the measurement accuracy of the soil resistivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the grounding form of the transmission line tower;

[0027] Figure 2 This is a schematic diagram of the four down conductors of the tower, the four sides of the grounding body and the four radial lines;

[0028] Figure 3 This is a schematic diagram after the auxiliary ground pole is driven into the ground;

[0029] Figure 4 This is a schematic diagram before the auxiliary ground electrode is driven into the center of the four-foot grounding position of the tower (measurement point O);

[0030] Figure 5 This is a schematic diagram of the equivalent resistance of the auxiliary ground electrode;

[0031] Figure 6 It is the equivalent resistance diagram of the tower grounding body;

[0032] Figure 7 It is a schematic diagram of the equivalent resistance value between the auxiliary ground electrode and the tower grounding body;

[0033] Figure 8 This is a schematic diagram of the resistance after constant current and voltage are injected between the auxiliary ground electrode and the tower grounding body;

[0034] Figure 9 It is a structural diagram of a soil resistivity detection device;

[0035] Figure 10 Schematic diagram of the area center point O of the four-corner tower;

[0036] Reference numerals: 1 down conductor, 2 grounding body edge, 3 grounding body radial line. DETAILED DESCRIPTION

[0037] The purpose of the present invention is to provide a soil resistivity measurement method and detection device, which are achieved through the following technical solutions:

[0038] The theoretical basis of the present invention is as follows:

[0039] The grounding form of transmission line towers generally adopts the grounding form of square frame plus radial grounding body (radial line), such as Figure 1 As shown in the figure, the four tower feet are arranged in a square, the length of the radial line is l1, and the length of its side is l2. If its burial depth is h and the diameter of the grounding body is d, the distance from the center point of the square on the ground to the four down conductors, the four sides of the grounding body and the four radial lines is as follows: Figure 2 As shown, according to GB / T50065-2011 Grounding Design Specifications for AC Electrical Installations, the grounding resistance value of the grounding body is shown in formula (1).

[0040]

[0041] The measured value means the equivalent resistance value from the transmission line tower to the soil at the infinite end.

[0042] If an auxiliary ground electrode is driven into the ground, Figure 3 As shown, its burial depth is p, and the diameter of the grounding body is m. Then the grounding resistance value of the auxiliary electrode (also a grounding body) is as shown in formula (2):

[0043]

[0044] The measured value means the equivalent resistance value from the auxiliary earth electrode to the infinite end soil.

[0045] Drive an auxiliary ground electrode into the center of the four grounding feet of the tower. Figure 4 As shown, the equivalent resistance diagram of the auxiliary ground electrode can be obtained as follows Figure 5 The tower grounding resistance diagram is shown as Figure 6 As shown, then the equivalent resistance R between the auxiliary ground electrode and the tower grounding resistance is as follows: Figure 7 Its value is shown in formula (3):

[0046]

[0047] A constant current I is injected between the auxiliary ground electrode and the tower, and the voltage U between the two is measured. The ratio between the two is R in formula (3), as shown in Figure 8 As shown:

[0048] Then the soil resistivity ρ at this location can be calculated according to formula (4):

[0049]

[0050] In order to inject a constant current I between the auxiliary ground electrode and the tower and measure the voltage U between the two, the present invention designs a soil resistivity detection device, such as Figure 9 As shown, one end of the soil resistivity detection device is securely connected to the tower via a metal clamp, and the other end is securely connected to the auxiliary ground electrode. The constant current source circuit generates a 20mA current, which is injected into the measurement circuit. The voltage detection circuit measures the voltage across the constant current source, that is, the voltage across resistor R. Furthermore, the voltage detection circuit has a high input resistance, and the current injected into the voltage detection circuit by the constant current source is negligible. Since the overhead ground wire is connected to the top of the transmission line tower, it has a shunt effect, but this shunt decreases with increasing frequency. Therefore, the AC frequency generated by the constant current source is between 0 and 20kHz.

[0051] The present invention is further described below with reference to specific embodiments.

[0052] Example 1

[0053] A soil resistivity detection device includes a voltage detection unit and a constant current source unit capable of adjusting frequency. One end of the constant current source unit is connected to a pole tower via a metal clip, and the other end is connected to an auxiliary ground electrode. The voltage detection unit is used to measure the voltage of the constant current source.

[0054] The frequency of the constant current source unit is 0-20 kHz.

[0055] The auxiliary ground electrode is made of galvanized round steel.

[0056] The auxiliary ground electrode has a length of 0.1 to 1 m and a diameter of 5 to 20 mm.

[0057] Example 2

[0058] A soil resistivity measurement method employs a soil resistivity detection device, an auxiliary ground electrode, and a grounding body to measure soil resistivity. The grounding body and the tower adopt a square plus radial grounding structure. The method comprises the following steps:

[0059] S1, specify the parameters of the auxiliary pole, specifically the length p and the diameter m of the auxiliary pole;

[0060] S2, clarify the relevant parameters of the tower and grounding body, specifically the radial length l1, the distance between adjacent tower feet (side length) l2, the burial depth h, and the grounding body diameter d;

[0061] S3, drive the auxiliary ground pole into the ground at the center point O of the four-corner tower, and the buried depth and length of the auxiliary ground pole are equal, both are p;

[0062] The area center point O of the four-corner tower is calculated according to the following steps:

[0063] like Figure 10 As shown, let the four endpoints of the four-corner tower be A, B, C, and D, determine the midpoints E, F, G, and H of AB, CD, AD, and BC respectively, connect EF and GH, and their intersection O is the center of the area.

[0064] S4, tightly connect the two ends of the soil resistivity detection device to the tower and the auxiliary ground electrode respectively, turn on the soil resistivity detection device, inject 20mA current into the auxiliary ground electrode, and detect the voltage value at both ends of the soil resistivity detection device;

[0065] S5, gradually increase the frequency, when the measured voltage value no longer changes, record the voltage value U, and use the formula Calculate the resistance between two points;

[0066] S6, using formula Calculate soil resistivity.

[0067] The soil resistivity measurement method and detection device of the present invention are used to detect the soil resistivity of three towers. The results are as follows:

[0068] For example, the round steel grounding element of Tower 1 has a side length of l2 = 10m, a radial length of l1 = 2m, a diameter of d = 16mm, and a burial depth of h = 2m. The auxiliary ground electrode in the measurement tool kit has a length of p = 0.3m and a diameter of m = 10mm. After determining the center points of the tower's four legs, drive the auxiliary ground electrode in, and use a soil resistivity tester to measure the resistance value to be 372Ω. Substitute this into the formula:

[0069]

[0070] The calculated result is ρ = 154.6Ω·m.

[0071] The grounding body parameters, auxiliary electrode parameters and test data used by Tower 2 and Tower 3 are shown in Table 1.

[0072] Table 1 Grounding body parameters and auxiliary electrode parameters and test data of tower 2 and tower 3

[0073]

[0074] It can be seen from the above results that the measurement method of the present invention can accurately measure the soil resistivity of transmission line towers, providing data support and technical guarantee for the evaluation of the lightning protection and grounding performance of transmission line towers.

Claims

1. A soil resistivity detection device, characterized in that: It includes a voltage detection unit and a constant current source unit capable of adjusting frequency. One end of the constant current source unit is connected to the tower through a metal clip, and the other end is connected to the auxiliary ground electrode. The voltage detection unit is used to measure the voltage of the constant current source.

2. A soil resistivity detection device according to claim 1, characterized in that: The frequency of the constant current source unit is 0-20 kHz.

3. A soil resistivity detection device according to claim 6, characterized in that: The auxiliary ground electrode is made of galvanized round steel.

4. A soil resistivity detection device according to claim 6, characterized in that: The auxiliary ground electrode has a length of 0.1 to 1 m and a diameter of 5 to 20 mm.

5. A soil resistivity measurement method, characterized in that: The soil resistivity is measured by using a soil resistivity detection device, an auxiliary ground electrode and a grounding body. The grounding body and the tower adopt a square plus radial grounding form.

6. A soil resistivity measurement method according to claim 5, characterized in that: The auxiliary ground pole is driven into the center point O of the four-corner tower, and the buried depth is equal to the length, both of which are p.

7. A soil resistivity measurement method according to claim 6, characterized in that: The area center point O of the four-corner tower is calculated according to the following steps: Suppose the four endpoints of the four-corner tower are A, B, C, and D, and determine the midpoints E, F, G, and H of AB, CD, AD, and BC respectively. Connect EF and GH, and their intersection O is the center of the area.

8. A soil resistivity measurement method according to claim 7, characterized in that: The following steps are involved: S1, specify the parameters of the auxiliary pole, specifically the length p and the diameter m of the auxiliary pole; S2, clarify the relevant parameters of the tower and grounding body, specifically the radial length l1, the distance between adjacent tower feet l2, the burial depth h, and the grounding body diameter d; S3, drive the auxiliary ground pole into the ground at the center point O of the four-corner tower, and the buried depth and length of the auxiliary ground pole are equal, both are p; S4, tightly connect the two ends of the soil resistivity detection device to the tower and the auxiliary ground electrode respectively, turn on the soil resistivity detection device, inject 20mA current into the auxiliary ground electrode, and detect the voltage value at both ends of the soil resistivity detection device; S5, gradually increase the frequency, when the measured voltage value no longer changes, record the voltage value U, and use the formula Calculate the resistance between two points; S6, using the formula Calculate soil resistivity.

9. A soil resistivity measurement method according to claim 8, characterized in that: The length of the radiation line in the grounding body is 1 to 10 meters, and the burial depth is 1 to 5 meters.

10. A soil resistivity measurement method according to claim 8, characterized in that: The diameter of the grounding body is 5 to 20 mm.

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