CN203456602U - Radial grounding device capable of reducing impulse grounding impedance - Google Patents

Abstract

The utility model discloses a radial grounding device capable of reducing impulse grounding impedance. The device comprises a central grounding body and four extended electrodes with the same length. One ends of the four extended electrodes are fixedly connected to the central grounding body, and the four extended electrodes and the central grounding body are located in the same plane. The central grounding body is bilaterally symmetrical in structure. More than two grounding electrode outgoing line ends are fixed on each of more than one of the extended electrodes. Through adding the grounding electrode outgoing line ends to the extended electrodes of the device, local electric field intensity of the device is enforced, the spark effect during impulse current dispersal is improved, and thus the device achieves the goal of reducing impulse grounding impedance.

Description

A radial grounding device with impact resistance reduction function

technical field

The utility model relates to the technical field of lightning protection and grounding of power transmission lines, in particular to a radial grounding device with the function of impact resistance reduction, which is suitable for the transformation and new grounding of existing centralized grounding devices for power transmission line towers in areas with high soil resistivity such as mountainous areas. Device design. the

Background technique

The impact grounding impedance of the centralized grounding device is an important parameter in the lightning protection design of the power system. When the transmission line is struck by lightning, the impact lightning current flows into the ground through the tower grounding device, and the impact grounding impedance has a direct impact on the lightning resistance performance of the transmission line under the action of a large impact current. In areas with high soil resistivity, due to the poor ability of the soil to dissipate current into the ground, the impact grounding impedance is often very large, which poses a threat to the safe operation of the system. Therefore, reducing the impact grounding impedance of centralized grounding devices in high soil resistivity areas is important The lightning resistance level of transmission lines is of great significance.

For a long time, the grounding devices of power transmission line poles and towers have been designed in accordance with the provisions of the "Design Regulations for Grounding of Electric Power Equipment" (SDJ8-79). In 1997, it was updated to "Grounding of AC Electrical Installations" (DL/T621-1997). The basic content of the grounding device for transmission line poles and towers in the two regulations has not changed. Therefore, the basic principles of grounding design for a long time are consistent. The frequency grounding resistance is converted into the impact grounding resistance by the impact coefficient to describe the performance characteristics of the grounding device under the impact current, and the structure of the grounding device is determined according to the value of the power frequency grounding resistance. However, when the actual measurement results of the power frequency grounding resistance meet the requirements, the impact grounding resistance does not meet the requirements. After the line is struck by lightning, it still cannot play its effective role, and the line still trips. That is to say, the design of the tower grounding device of transmission lines should be analyzed from the impact dissipation characteristics, not only from the perspective of power frequency grounding resistance.

To reduce the impact grounding resistance of transmission line towers, the measures often used in projects mainly include increasing the size of the grounding body, using natural grounding bodies, horizontal extension grounding, deep buried grounding, partial soil replacement, use of resistance reducing agents, blasting grounding etc. However, each of these methods has its own relative application conditions. It is still very difficult to design a grounding device that is technically and economically reasonable and meets the requirements of impulse grounding impedance in areas with high soil resistivity. the

Contents of the invention

The technical problem to be solved by the utility model is to provide a radial grounding device with the function of impact resistance reduction in view of the deficiencies of the prior art. By changing the local structure of the centralized grounding device, the local electric field intensity is enhanced to promote The spark effect to achieve the purpose of reducing the impact grounding impedance.

In order to solve the above technical problems, the technical solution adopted by the utility model is: a radial grounding device with the function of impact resistance reduction, including a middle grounding body and four extension electrodes of equal length, one end of the four extension electrodes is connected to the The middle grounding body is fixedly connected, and the four extension electrodes are located on the same plane as the middle grounding body, the structure of the left and right sides of the middle grounding body is symmetrical, and more than one extension electrode is fixed with two or more Ground terminal.

The middle grounding body is a square, and the four extension electrodes are respectively fixedly connected to the four vertices of the square.

The middle grounding body is straight, and two ends of the straight line are respectively connected to two grounding electrodes.

The outlet end of the ground electrode intersects the extension electrode vertically, and the outlet end of the ground electrode is on the same plane as the extension electrode, and the middle part of the outlet end of the ground electrode is fixed on the extension electrode. The distance between two adjacent ground electrode outlet terminals on the root extension electrode is 1.5×H/2, where H is the length of the ground electrode outlet terminal, and the value range of H is 1.5m ~ 2m; for the square middle ground body, The distance between any vertex of the square and the ground electrode outlet end close to the vertex on the extension electrode connected to the vertex is 1.5S, where S is the side length of the square; The distance between the connected extension electrode and the terminal of the ground electrode outlet near this end is 1.5d, where d is the straight line length.

One end of the ground electrode outlet end is vertically connected to the extension electrode, and the ground electrode outlet end is perpendicular to the plane where the extension electrode is located, and the distance between two adjacent ground electrode outlet ends on each extension electrode is ≥2 H, where H is the length of the terminal of the grounding electrode outlet, and the value range of H is 1.5m~2m; for the grounding body in the middle of the square, the distance between any vertex of the square and the grounding electrode close to the vertex on the extension electrode connected to the vertex The distance between the outlet ends is 1.5S, where S is the side length of the square; for a straight-line central grounding body, the distance between any end of the straight line and the end of the ground electrode on the extension electrode connected to the end is 1.5d, where d is the length of the line.

The setting of the spacing between the terminals of the ground electrode outlets and the distance between the terminals of the ground electrode outlets and the middle grounding body can reduce the added shielding effect between the adjacent ground electrode outlets, so that the effect of dispersing air is better .

Compared with the prior art, the utility model has the beneficial effects as follows: the utility model increases the grounding electrode outlet terminal on the extension electrode of the grounding device, enhances the local electric field strength of the grounding device, and promotes the impact and dispersion process. The spark effect achieves the purpose of reducing the impact grounding impedance.

Description of drawings

Fig. 1 is a schematic diagram of the horizontal fixation of the terminal of the ground electrode outlet in the first embodiment of the present invention;

Fig. 2 is a schematic diagram of the vertical fixation of the terminal of the ground electrode outlet in the first embodiment of the present invention;

Fig. 3 is a schematic diagram of the horizontal fixation of the outlet end of the ground electrode according to the second embodiment of the present invention;

Fig. 4 is a schematic diagram of the vertical fixation of the terminal of the ground electrode outlet in the second embodiment of the present invention;

Fig. 5 is a schematic diagram of a platform for a simulated test of the improved centralized grounding device of the present invention.

Figure 6(a) is the distribution diagram of the cremation discharge area when the existing radial grounding device does not add the outlet terminal; Figure 6(b) is the distribution diagram of the cremation discharge area after the outlet terminal is added to the radial grounding device of the present utility model; The black area in Figure 6(a) and Figure 6(b) is the spark discharge area, and its field strength is greater than the soil breakdown field strength.

Detailed ways

As shown in Fig. 1 and Fig. 2, the grounding device of the first embodiment of the present utility model is an iron tower grounding device, comprising a central grounding body 1 and four extension electrodes 3 of equal length, one end of the four extension electrodes 3 is connected to the The middle grounding body 1 is fixedly connected, and the four extension electrodes 3 are located on the same plane as the middle grounding body 1. The left and right sides of the middle grounding body 1 are symmetrical in structure, and two of the four extension electrodes 3 are fixed on the same plane. The above ground electrode outlet terminal 2, wherein the middle ground body is a square.

As shown in Figure 1, when the ground electrode outlet terminal 2 and the extension electrode 3 perpendicularly intersect and are on the same plane, the middle part of the ground electrode outlet terminal 2 is welded on the extension electrode 3, and the adjacent two electrodes on each extension electrode 3 The distance between the terminal 2 of the ground electrode outlet is 1.5×H/2, where H is the length of the terminal 2 of the ground electrode outlet, and the range of H is 1.5m to 2m; the distance between any vertex of the square and the extension electrode 3 connected to the vertex The distance from the terminal of the ground electrode outlet close to the vertex is 1.5S, where S is the side length of the square.

As shown in Figure 2, the ground electrode outlet terminal 2 is vertically intersected with the extension electrode 3 and the ground electrode outlet terminal is perpendicular to the plane where the extension electrode 3 is located. The two adjacent ground electrode outlet terminals 2 on each extension electrode 3 Spacing ≥ 2 H, where H is the length of the ground electrode outlet terminal 2, and the value range of H is 1.5m to 2m; the distance between any vertex of the square and the extension electrode 3 connected to the vertex is close to the ground electrode outlet terminal of the vertex The distance is 1.5S, where S is the side length of the square, and S is 8-10m.

As shown in Fig. 3 and Fig. 4, the grounding device of the second embodiment of the present invention is a cement rod radial grounding device, and the middle grounding body 1 is linear, and any end of the straight line is close to the extended electrode connected to the end. The distance between the terminals of the ground electrode outlet at the end is 1.5d, where d is the length of the straight line, and d is 10m. The distances between the terminals of the ground electrode outlets in Fig. 3 and Fig. 4 are the same as those in Fig. 1 and Fig. 2 respectively.

The length of the extension electrode is generally L=20~50m.

The length of the grounding electrode outlet should be appropriate to avoid the shielding effect on the original centralized grounding device; it should not be too short, otherwise the added grounding electrode outlet will not be able to spread the flow due to the shielding effect of the centralized grounding device itself; it should not be too long, because the grounding The pole has an inductive effect under the high-frequency impact current, and the part of the ground pole that is too long cannot be used, and it also cannot play the role of spreading current, resulting in waste. In the first embodiment and the second embodiment, the length of the terminal of the ground electrode outlet is 2m.

As shown in Figure 5, the simulation test device used in the utility model mainly includes an impact high voltage and high current generator, a simulated earth test tank, centralized grounding devices of different structures, a tubular shunt, an impact voltage divider, a digital oscilloscope, etc. . The material of the centralized grounding device in the test is the same as that of the actual grounding device. According to the principle of the similarity theory of the impact test, the size and buried depth are reduced in proportion to the actual situation. Wiring according to the test principle diagram shown in Figure 5. Do the pre-test preparations and start the test. Use a digital oscilloscope to record the waveforms of the impulse current and impulse voltage under different grounding devices, read the peak values of the impulse voltage and impulse current, and calculate the impulse grounding resistance of the simulated grounding device.

Using the above-mentioned devices to carry out multiple groups of centralized grounding device shock dissipation contrast test. Change the local structure of the grounding device, add outlet terminals to the grounding device, and consider the influence of the number and position of the added outlets at the same time, and analyze and compare the impact grounding resistance in different situations. The spark discharge area of a group of comparative centralized grounding devices when impacting diffuse flow is shown in Figure 6(a) and Figure 6(b). It can be seen from Fig. 6(a) and Fig. 6(b) that by adding the outlet terminal at the appropriate position of the conventional centralized grounding device, the spark discharge area during the shock dissipation can be significantly enlarged, thereby reducing the shock grounding resistance, which proves that this Effectiveness of utility model devices.

At the same time, the soil in the artificial sand tank is adjusted by changing the water content to adjust its soil resistivity, and the impact dispersion test is carried out on the comparison group of centralized grounding devices under different soil resistivity conditions, especially in the case of high soil resistivity, as shown in the figure The improved centralized grounding device shown in Figures 1 to 4 has a more significant resistance reduction effect, which proves the effectiveness of the utility model device under high soil resistivity. the

Claims (9)

1. one kind possesses the radiation earthing device that resistance function falls in impact, comprise middle part earth electrode (1) and four isometric prolongation electrodes (3), described four prolongation electrode (3) one end are fixedly connected with described middle part earth electrode (1), and described four prolongation electrodes (3) are in the same plane with described middle part earth electrode (1), described middle part earth electrode (1) left and right sides symmetrical configuration, it is characterized in that, on the above prolongation electrode (3), be fixed with two above earth electrode wire outlet ends (2).

According to claim 1 possess impact the radiation earthing device fall resistance function, it is characterized in that, described middle part earth electrode (1) be square, described four prolongation electrodes (3) are fixedly connected with described foursquare four summits respectively.

According to claim 1 possess impact the radiation earthing device fall resistance function, it is characterized in that, described middle part earth electrode (1) is linear, described straight line two ends connect respectively two described grounding electrodes (3).

4. according to possessing described in claim 2 or 3, impact the radiation earthing device that falls resistance function, it is characterized in that, described earth electrode wire outlet end (2) intersects vertically with described prolongation electrode (3), and described earth electrode wire outlet end (2) is in the same plane with described prolongation electrode (3).

According to claim 5 possess impact the radiation earthing device fall resistance function, it is characterized in that, in the middle part of described earth electrode wire outlet end (2), be fixed on described prolongation electrode (3).

6. according to possessing described in claim 2 or 3, impact the radiation earthing device that falls resistance function, it is characterized in that, described earth electrode wire outlet end (2) one end and vertical connection of described prolongation electrode (3), and described earth electrode wire outlet end (2) is vertical with described prolongation electrode (3) place plane.

According to claim 5 possess impact the radiation earthing device fall resistance function, it is characterized in that, every spacing that extends the adjacent two earth electrode wire outlet ends (2) on electrode (3) is 1.5 * H/2, wherein H is the length of earth electrode wire outlet end (2), and H span is 1.5m～2m; For square middle part earth electrode (1), the distance of the upper earth electrode wire outlet end near this summit of prolongation electrode (3) that square arbitrary vertex distance is connected with this summit is 1.5S, and wherein S is the foursquare length of side; For linear middle part earth electrode (1), the distance of the upper earth electrode wire outlet end near this end of prolongation electrode (3) that the arbitrary end distance of straight line is connected with this end is 1.5d, and wherein d is straight length.

According to claim 6 possess impact the radiation earthing device fall resistance function, it is characterized in that, every spacing >=2 H that extends the adjacent two earth electrode wire outlet ends (2) on electrode (3), wherein H is the length of earth electrode wire outlet end (2), H span is 1.5m～2m; For square middle part earth electrode (1), the distance of the upper earth electrode wire outlet end near this summit of prolongation electrode (3) that square arbitrary vertex distance is connected with this summit is 1.5S, and wherein S is the foursquare length of side; For linear middle part earth electrode (1), the distance of the upper earth electrode wire outlet end near this end of prolongation electrode (3) that the arbitrary end distance of straight line is connected with this end is 1.5d, and wherein d is straight length.

9. according to possessing described in claim 7 or 8, impact the radiation earthing device that falls resistance function, it is characterized in that, on described four prolongation electrodes (3), be all fixed with earth electrode wire outlet end (2).

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