A lightning protection grounding device for graded discharge of lightning current and a graded discharge method

Abstract

The present invention provides a lightning protection grounding device and method for graded discharge of lightning current. The grounding device includes a head-end grounding copper bar, a tail-end grounding copper bar and at least one middle grounding copper bar. The head-end grounding copper bar and the middle grounding copper bar are connected to the earth through grounding electrodes respectively. The head-end grounding copper bar and the middle grounding copper bar are connected in parallel circuit through a head-end protection gap and a head-end high-frequency wave arrester. A tail-end high-frequency wave arrester is connected in series between the middle grounding copper bar and the tail-end grounding copper bar. The head-end grounding copper bar is connected to the down conductor of the lightning rod, the tail-end grounding copper bar is connected to the working ground of the electrical equipment, and the tail-end grounding copper bar is also connected to the power supply neutral line of the electrical equipment. The present invention can realize the graded discharge of lightning current to the ground, and at the same time gradually reduce the residual pressure of the discharge current of each grounding copper bar, so that the working ground of the electrical equipment is always at the lowest potential level. The present invention is suitable for electrical equipment on-site occasions where it is impossible to provide a large land area to build a ground network or improve the cost-effectiveness of grounding.

Description

Technical Field

[0001] The present invention relates to the technical field of lightning protection, and in particular to a lightning protection grounding device for graded discharge of lightning current and a graded discharge method. Background Art

[0002] Lightning is a discharge phenomenon that exists in nature. When the amount of charge in the cloud accumulates to a certain level, it will discharge in the form of thunder. With the accelerated development of the mobile communication industry in recent years, the coverage of communication networks around the world is also expanding. Mobile communication base stations are often affected by lightning during operation, resulting in equipment failure, damage, and power outages, which greatly affects the signal transmission quality and signal coverage. The frequency of base stations is getting higher and higher, and communication equipment is getting smaller and smaller. With the popularization of high-frequency mobile communication networks, the number of mobile communication base stations has also increased significantly to a certain extent. The construction of standard grounding networks based on traditional lightning protection technology occupies a large area, especially for cities where every inch of land is valuable. It is almost impossible to build standard grounding networks for communication base stations. If the communication equipment is not grounded, when the lightning current invades, the lightning current will pass through the physical connection lines (power lines, signal lines, etc.) of the electrical equipment as a discharge channel, causing overcurrent and damage to the electrical equipment; or only a small ground network is made (the ground resistance is too high), even if an equipotential connector (SPD) is used, when the lightning invades, the high potential will instantly reach the functional grounding points of the electrical equipment (lightning protection grounding, safety protection ground, work ground, etc.), and the work ground is often the reference ground of the high integrated circuits in the electrical equipment, and its circuits use a large number of integrated chips, inductive and capacitive components, and its withstand voltage level is extremely limited. The introduction of high potential at the work ground will cause fatal damage to the high integrated circuits in the electrical equipment.

[0003] The utility model patent with announcement number CN209150715U discloses a device for multi-channel isolated grounding to resist strong lightning surges and prevent burning. However, there is a problem of back-breakback caused by instantaneous ground potential rise. There is still a problem of high potential instantly reaching various functional grounding points of electrical equipment, namely lightning protection grounding, safety protection ground, working ground, etc., which is particularly obvious when the grounding resistance is large. The residual pressure of the working grounding cannot be effectively suppressed, and the needs of special land use occasions cannot be met. In order to meet the needs of special occasions, combined with a small grounding network, a hierarchical discharge based on equipotential needs to be realized, and the residual pressure of the grounding copper busbar is gradually reduced to make the working ground of electrical equipment at the lowest potential level. Summary of the invention

[0004] In order to solve the above-mentioned technical problems, the present invention provides a lightning protection grounding device for graded discharge of lightning current, and its specific technical solution is as follows:

[0005] A lightning protection grounding device for graded discharge of lightning current includes a head-end grounding copper bar, a tail-end grounding copper bar and at least one middle grounding copper bar, wherein the head-end grounding copper bar and the middle grounding copper bar are connected to the earth through grounding electrodes respectively, the head-end grounding copper bar and the middle grounding copper bar are connected in parallel circuit through a head-end protection gap and a head-end high-frequency wave arrester, a tail-end high-frequency wave arrester is connected in series between the middle grounding copper bar and the tail-end grounding copper bar, the head-end grounding copper bar is connected to the down conductor of the lightning rod, the tail-end grounding copper bar is connected to the working ground of the electrical equipment, and the tail-end grounding copper bar is also connected to the power supply neutral line of the electrical equipment. The head-end grounding copper bar, the middle grounding copper bar and the tail-end grounding copper bar form a graded discharge form, the voltage loaded on each grounding copper bar is reduced step by step, and the potential of the tail-end grounding copper bar connected to the working ground of the electrical equipment is ensured to be always at the lowest level.

[0006] Furthermore, the intermediate grounding copper bus is connected to the metal component of the optical fiber and / or is connected to the mains at the same potential through an equipotential connector.

[0007] Furthermore, it includes a first intermediate grounding copper bar and a second intermediate grounding copper bar, wherein the first intermediate grounding copper bar is connected to the second intermediate grounding copper bar through an intermediate protection gap and an intermediate high-frequency wave arrester in parallel circuit, the first intermediate grounding copper bar is connected to the metal component of the optical fiber, and the second intermediate grounding copper bar is connected to the mains equipotential through an equipotential connector. According to the probability and intensity of the possibility of lightning current intrusion, the lightning rod is connected to the head end grounding copper bar because the direct lightning current is the largest. The optical fiber contains metal armor components that may produce direct lightning and induced lightning, so the optical fiber is connected to the first intermediate copper bar, and the power supply line may produce induced lightning, so it is connected to the second intermediate grounding copper bar. The above-mentioned setting is conducive to graded discharge of the ground from high to low according to the probability and intensity of various intruding lightning currents. The energy of the lightning current is weakened in layers to ensure that the grounding copper bar connected to the working ground of the electrical equipment is at a low potential level.

[0008] Furthermore, the breakdown threshold of the head-end protection gap is 400~1200V, and the current capacity is 50~100KA (10 / 350μs waveform); the breakdown threshold of the middle protection gap is 800~1600V, and the current capacity is 20~50KA (10 / 350μs waveform).

[0009] Furthermore, the inductance of the head-end high-frequency wave trap and the middle high-frequency wave trap are 300μH~10mH respectively, and the maximum current passing therethrough is 30A; the inductance of the tail-end high-frequency wave trap is 600μH~10mH, and the maximum current passing therethrough is 15A.

[0010] Furthermore, normally closed contactors are respectively connected in series on the circuit where the head-end high-frequency wave trap is located and on the circuit where the middle high-frequency wave trap is located.

[0011] Furthermore, an air switch is connected in series between the tail grounding copper bar and the power supply neutral line. By disconnecting the air switch, the fault current in the neutral line of the power supply system is prevented from causing heating of the grounding electrode and electric shock accidents.

[0012] Furthermore, it also includes an intelligent detection module, which includes a ground resistance measurement module and a switch quantity detection module. The ground resistance measurement module is used to measure the grounding resistance of the grounding electrode corresponding to each grounding copper busbar, and the switch quantity detection module is used to detect the state of the air switch. The ground resistance measurement module and the switch quantity detection module are respectively connected to the MCU processor, and the ground resistance measurement module and the switch quantity detection module transmit the detected information to the MCU processor.

[0013] Furthermore, normally closed contactors are respectively connected in series on the circuit where the head-end high-frequency wave trap is located and on the circuit where the middle high-frequency wave trap is located.

[0014] Furthermore, the electrical equipment includes a signal transceiver and a power cabinet, and the metal casing, power lines, and signal lines of the electrical equipment are directly or indirectly connected to the middle grounding copper busbar to form an equipotential structure, and a discharge channel is provided by the grounding electrode connected thereto.

[0015] In addition, the present invention also provides a graded discharge method, which adopts a protective gap and a high-frequency wave arrester in parallel to connect the head-end grounding copper bar and the middle grounding copper bar, the head-end grounding copper bar and the middle grounding copper bar are respectively connected to the earth through a grounding electrode to form a structure for graded discharge of lightning current, and at the same time, a tail-end high-frequency wave arrester is connected in series between the middle grounding copper bar and the tail-end grounding copper bar, so that the high and low potentials between the head-end grounding copper bar, the middle grounding copper bar and the tail-end grounding copper bar are separated and the potentials are reduced in sequence; the head-end grounding copper bar is connected to the down conductor of the lightning rod, the tail-end grounding copper bar is connected to the working ground of the electrical equipment, and the optical fiber and the mains power are connected to the middle grounding copper bar in sequence according to the size of the direct lightning current or the induced lightning current, and graded discharge is performed according to the size of the intruding lightning current; the electrical equipment is at the same potential when the lightning current invades, and it is ensured that the working ground of the electrical equipment is always at the lowest potential level.

[0016] Furthermore, the breakdown voltage threshold of the protection gap is smaller than the voltage loaded on the high-frequency wave trap when the maximum through-current of the high-frequency wave trap passes through the high-frequency wave trap.

[0017] Beneficial effects: 1. The present invention adopts the method of connecting the protection gap and the high-frequency wave arrester in parallel circuit, and the barrier effect of the high-frequency wave arrester when the lightning current invades, the mutual cooperation and coordination of the grounding electrode leakage and the protection gap conduction, so that multiple grounding copper bars form a graded discharge structure. No matter where the lightning current invades from, if the lightning current is too large, it will break through the protection gap and discharge to the ground step by step through each grounding copper bar. The potential of each grounding copper bar decreases step by step, so that the potential of the tail grounding copper bar connected to the electrical equipment is always at the lowest level.

[0018] 2. In the absence of lightning current intrusion, the high-frequency wave arrester is in a low-resistance state, and the grounding electrodes of multiple grounding copper bars are jointly grounded to form a ground grid with relatively small ground resistance; through the repeated grounding of the neutral line of the power supply of the electrical equipment, a reliable and safe working ground is provided for the electrical equipment, and an air switch is connected in series between the neutral lines of the power supply. By disconnecting the air switch, the fault current in the neutral line of the power supply system is prevented from causing heating of the grounding electrode and electric shock accidents; when there is an intrusion of lightning waves, the high-frequency wave arrester and the discharge gap are coordinated to discharge the current separately or gradually, ensuring that the grounding copper bar connected to the working ground of the electrical equipment is at a low potential level.

[0019] 3. The present invention uses the graded discharge and high and low potential isolation technology of the limited grounding electrode to ensure the safe operation of electrical equipment under the condition of small footprint and high grounding resistance of the limited grounding electrode, thus greatly saving land occupation, capital and personnel investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of embodiment 1 of the present invention;

[0021] Figure 2 is a schematic diagram of embodiment 2 of the present invention;

[0022] Figure 3 is a schematic diagram of embodiment 3 of the present invention;

[0023] Figure 4 is a schematic diagram of embodiment 4 of the present invention;

[0024] Figure 5 This is a schematic diagram of Example 5 of the present invention.

[0025] Figure numerals: 1-head end grounding copper bar; 2-first middle grounding copper bar; 3-second middle grounding copper bar; 4-tail end grounding copper bar; 5-middle grounding copper bar; 6-head end protection gap; 7-middle protection gap; 8-head end high frequency wave blocker; 9-middle high frequency wave blocker; 10-tail end high frequency wave blocker; 11-grounding electrode; 12-lightning rod; 13-optical fiber; 14-mains power; 15-electrical equipment; 16-equipotential connector; 17-air switch; 18-normally closed contactor; 19-intelligent detection module; 20-ground resistance measurement module; 21-lightning strike counting module; 22-switch quantity detection module; 23-MCU processor. DETAILED DESCRIPTION

[0026] In order to make the purpose, principle and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and possible embodiments of lightning intrusion. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] Example 1

[0028] like Figure 1 As shown, it includes a head-end grounding copper bar, a tail-end grounding copper bar and at least one middle grounding copper bar, the head-end grounding copper bar and the middle grounding copper bar are connected to the earth through grounding electrodes respectively, the head-end grounding copper bar and the middle grounding copper bar are connected in parallel circuit through a head-end protection gap and a head-end high-frequency wave arrester, a tail-end high-frequency wave arrester is connected in series between the middle grounding copper bar and the tail-end grounding copper bar, the head-end grounding copper bar is connected to the down conductor of the lightning rod, the tail-end grounding copper bar is connected to the working ground of the electrical equipment, and the tail-end grounding copper bar is also connected to the power neutral line of the electrical equipment.

[0029] In this embodiment, the soil conductivity ρ is first determined. Generally speaking, the soil conductivity suitable for lightning current discharge is 50~300Ω.M. The soil conductivity is selected as the limit value 300Ω.M for calculation. The grounding electrode adopts a galvanized steel pipe with a diameter of 50mm. The calculation formula of the power frequency grounding resistance of the galvanized steel pipe is: R 地=Kρ where K is the simplification coefficient. When a galvanized steel pipe with a diameter of 50mm and a length of 2M is used, the simplification coefficient can be taken as 0.38, that is, the grounding resistance of each grounding electrode is: 0.38*300=114Ω; the breakdown threshold of the head-end protection gap is selected as 1200V, the flow capacity is 50KA (10 / 350μs waveform), the inductance of the head-end high-frequency wave arrester is 300μH, and the maximum current that can pass is 30A, and the inductance of the tail-end high-frequency wave arrester is 600μH, and the maximum current that can pass is 15A. When the lightning current with a frequency of 50KHz invades the lightning rod, the lightning current is also shunted to the head-end high-frequency wave arrester. At this time, the head-end high-frequency wave arrester will generate an impedance of about 2πfL=94Ω, where f is the frequency of the lightning current and L is the inductance. When the current intensity through the head-end high-frequency wave arrester reaches the maximum current, the voltage difference between the two ends of the head-end high-frequency wave arrester exceeds 2800V, which is much larger than the breakdown threshold of the head-end protection gap. Therefore, the head-end protection gap is connected, and the lightning current is discharged to the ground through the middle grounding electrode. At this time, the grounding electrodes of the head-end grounding copper bar and the middle grounding copper bar are involved in the convergence, and the comprehensive power frequency grounding resistance is about 60Ω. It is more conducive to the discharge of the direct lightning current from the grounding electrode corresponding to the head-end grounding copper bar or the grounding electrode connected to the adjacent grounding copper bar. This hierarchical discharge method weakens the energy of the direct lightning current in layers to ensure that the grounding copper bar connected to the working ground of the electrical equipment is at a low potential level.

[0030] Example 2

[0031] like Figure 2 As shown, a lightning protection grounding device for graded discharge of lightning current includes a head-end grounding copper bar, a tail-end grounding copper bar and at least one intermediate grounding copper bar, the head-end grounding copper bar and the intermediate grounding copper bar are connected to the earth through grounding electrodes respectively, the head-end grounding copper bar and the intermediate grounding copper bar are connected in parallel circuit through a head-end protection gap and a head-end high-frequency wave arrester, a tail-end high-frequency wave arrester is connected in series between the intermediate grounding copper bar and the tail-end grounding copper bar, the tail-end grounding copper bar is connected to a power neutral line, the head-end grounding copper bar is connected to a down conductor of a lightning rod, the tail-end grounding copper bar is connected to a working ground of an electrical device, and the intermediate grounding copper bar is connected to a metal armored component of an optical fiber.

[0032] In this embodiment, the lightning current discharge method is the same as that of Embodiment 1, that is, the grounding electrodes of the head-end grounding copper bar and the middle grounding copper bar are connected in parallel circuit through the head-end protection gap and the head-end high-frequency wave trap for graded discharge. The difference is that the metal armor component of the optical fiber is connected to the middle grounding copper bar. Since there is a probability of direct lightning strikes on the metal armor component of the optical fiber, but the probability of direct lightning strikes is small, there is also a possibility of induced lightning, and the energy of induced lightning is less than the energy of direct lightning strikes. Therefore, the metal armor component of the optical fiber is connected to the middle grounding copper bar, which is more conducive to the discharge of direct lightning current or induced lightning current from the grounding electrode corresponding to the middle grounding copper bar or the grounding electrode connected to the adjacent grounding copper bar. This graded discharge method greatly suppresses the lightning current invading the metal armor component of the optical fiber, weakens it in layers, and ensures that the grounding copper bar connected to the working ground of the electrical equipment is at a low potential level.

[0033] Example 3

[0034] like Figure 3 As shown, a lightning protection grounding device for graded discharge of lightning current includes a head-end grounding copper bar, a tail-end grounding copper bar and at least one intermediate grounding copper bar, the head-end grounding copper bar and the intermediate grounding copper bar are connected to the earth through grounding electrodes respectively, the head-end grounding copper bar and the intermediate grounding copper bar are connected in parallel circuit through a head-end protection gap and a head-end high-frequency wave arrester, a tail-end high-frequency wave arrester is connected in series between the intermediate grounding copper bar and the tail-end grounding copper bar, the tail-end grounding copper bar is connected to a power neutral line, the head-end grounding copper bar is connected to a down conductor of a lightning rod, the tail-end grounding copper bar is connected to a working ground of an electrical equipment, and the intermediate grounding copper bar is connected to the mains through an equipotential connector.

[0035] In this embodiment, the lightning current discharge method is the same as that of Embodiment 1, that is, the grounding electrodes of the head-end grounding copper bar and the middle grounding copper bar are connected in parallel circuit through the head-end protection gap and the head-end high-frequency wave trap for hierarchical discharge. The difference is that the middle grounding copper bar is connected to the mains through an equipotential connector. Since the mains is mainly affected by induced lightning, the middle grounding copper bar is connected to the mains through an equipotential connector, which is more conducive to discharging the induced current from the mains from the grounding electrode corresponding to the middle grounding copper bar or the grounding electrode connected to the adjacent grounding copper bar. At the same time, the SPD equipotential connector is used to make the functional grounding of each electrical equipment reach an equipotential structure.

[0036] Example 4

[0037] like Figure 4As shown, a lightning protection grounding device for graded discharge of lightning current comprises a head-end grounding copper bar, a tail-end grounding copper bar and two intermediate grounding copper bars, which are respectively a first intermediate grounding copper bar and a second intermediate grounding copper bar. The head-end grounding copper bar, the first intermediate grounding copper bar and the second intermediate grounding copper bar are connected to the earth through grounding electrodes respectively. The head-end grounding copper bar and the first intermediate grounding copper bar are connected in parallel circuit through a head-end protection gap and a head-end high-frequency wave trap. The first intermediate grounding copper bar and the second intermediate grounding copper bar are connected in parallel circuit through an intermediate protection gap and an intermediate high-frequency wave trap. A tail-end high-frequency wave trap is connected in series between the second intermediate grounding copper bar and the tail-end grounding copper bar. The tail-end grounding copper bar is connected to a power neutral line. The head-end grounding copper bar is connected to a down conductor of a lightning rod. The tail-end grounding copper bar is connected to a working ground of an electrical device. The first intermediate grounding copper bar is connected to a metal armored component of an optical fiber. The second intermediate grounding copper bar is connected to the mains through an equipotential connector. An air switch is connected in series between the tail-end grounding copper bar and the power neutral line. The rated current of the air switch is 10A.

[0038] In this embodiment, a head-end grounding copper bar, a first middle grounding copper bar, and a second middle grounding copper bar are connected in sequence in a manner of a protective gap in parallel with a high-frequency wave arrester. At the same time, a tail-end high-frequency wave arrester is connected in series between the middle grounding copper bar and the tail-end grounding copper bar to form a structure for graded discharge of lightning current. The optical fiber and the mains power are connected to the middle grounding copper bar in sequence according to the size of the lightning current or the induced current, so that the protective ground of the electrical equipment is always at the lowest potential.

[0039] In this embodiment, the breakdown threshold of the head-end protection gap is 1200V, the current capacity is 50KA (10 / 350μs waveform), the breakdown threshold of the middle protection gap is 1600V, the current capacity is 35KA (10 / 350μs waveform), the inductance of the head-end high-frequency wave arrester and the middle high-frequency wave arrester are both 300μH, and the maximum current that can pass is 30A. When the voltage difference across the head-end high-frequency wave arrester exceeds the breakdown voltage threshold of the head-end protection gap, the head-end protection gap is activated, the head-end grounding copper bar and the first middle grounding copper bar are both involved in the convergence, and the comprehensive power frequency grounding resistance is about 60Ω. Similarly, when the residual lightning current is shunted to the middle high-frequency wave arrester, if the voltage across the middle high-frequency wave arrester is greater than the voltage threshold of the middle protection gap, the middle protection gap is activated, the head-end grounding copper bar, the first middle grounding copper bar and the second middle grounding copper bar are all involved in the convergence, and the comprehensive power frequency grounding resistance is about 40Ω. This graded discharge structure achieves equal potential in layers, weakens the energy of the intruding lightning current from high potential to low potential, and ensures that the grounding copper busbar connected to the working ground of the electrical equipment is at a low potential level.

[0040] Example 5

[0041] like Figure 5 As shown, this embodiment adds an intelligent detection module on the basis of Embodiment 4, and monitors the grounding resistance, switch value and number of lightning strikes through sensors and measurement technology. The intelligent detection module includes a ground resistance measurement module, a lightning strike counting module, a lightning peak and waveform monitoring module, an SPD leakage current monitoring module and a switch value monitoring module. The ground resistance measurement module is used to measure the grounding resistance of the grounding electrode corresponding to each grounding copper busbar; the circuit where the head-end high-frequency wave trap is located and the circuit where the middle high-frequency wave trap is located are respectively connected in series with normally closed contactors. In normal work, the normally closed contactor is closed, and the normally closed contactor is closed when measuring the grounding resistance. The contactor is disconnected; the lightning strike counting module is used to record the number of lightning strikes on the lightning rod, the metal armor components of the optical fiber and the mains; the lightning peak and waveform monitoring module is used to record the peak and waveform characteristics of the invading lightning current; the SPD leakage current monitoring module is used to monitor the equipotential working state, parameter changes and service life; the switch quantity detection module is used to detect the state of the air switch; the ground resistance measurement module, the lightning peak and waveform monitoring module, the SPD leakage current monitoring module, the lightning strike counting module and the switch quantity monitoring module are respectively connected to the MCU processor, and the detected information is transmitted to the MCU processor.

[0042] In this embodiment, the ground resistance measurement module can be but not limited to the ground resistance measurement device and measurement disclosed in the invention patent with application number 2019109522762 to measure the ground resistance of the grounding copper busbar grounding electrode; the lightning counting module can be but not limited to the lightning counting device disclosed in the utility model with application number 2019211105984; the lightning peak and waveform monitoring module can be but not limited to the method disclosed in the invention patent with application number 202010111232X for measurement; the SPD leakage current monitoring module can be but not limited to the device disclosed in the utility model patent with application number: 2019216861386 for monitoring; the switch quantity detection module can be but limited to the series node switch quantity monitoring module disclosed in the utility model patent with application number 2015209320927.

[0043] The intelligent detection module monitors data such as ground resistance, lightning peak value and waveform, SPD leakage current, air switch status, and lightning current intrusion count, and warns that the parameters of each electrical component match the conditions or provides data for adjusting the parameters of the electrical components to achieve the best performance of graded discharge; at the same time, it provides strong guarantees for timely troubleshooting and normal operation of electrical equipment.

[0044] In the above embodiments 1-5, the electrical equipment includes but is not limited to signal transceivers, power cabinets, air conditioners, switches, radiators and other equipment. The metal casing, power lines, and signal lines of the electrical equipment are directly or indirectly connected to the middle grounding copper busbar to form an equipotential structure, and the grounding electrode connected thereto provides a discharge channel; its working ground is connected to the tail grounding copper.

[0045] It should be noted that the above-mentioned lightning protection grounding device can be applied not only to the arrangement of lightning protection of base stations, but also to places such as gas stations and computer rooms that require lightning protection grounding. The above is only a preferred embodiment of the present invention and is not used to limit the present invention. Although the present invention is described in detail with reference to the above-mentioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the above-mentioned embodiments, or to replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A lightning protection grounding device for graded discharge of lightning current, characterized in that: It comprises a head-end grounding copper bar, a tail-end grounding copper bar and at least one middle grounding copper bar, wherein the head-end grounding copper bar and the middle grounding copper bar are connected to the earth through grounding electrodes respectively, the head-end grounding copper bar and the middle grounding copper bar are connected in parallel circuit through a head-end protection gap and a head-end high-frequency wave arrester, a tail-end high-frequency wave arrester is connected in series between the middle grounding copper bar and the tail-end grounding copper bar, the head-end grounding copper bar is connected to the down conductor of the lightning rod, the tail-end grounding copper bar is connected to the working ground of the electrical equipment, and the tail-end grounding copper bar is also connected to the power supply neutral line of the electrical equipment; The intermediate grounding copper bar is connected to the metal component of the optical fiber and / or is connected to the mains at the same potential through an equipotential connector; It includes a first intermediate grounding copper bar and a second intermediate grounding copper bar, wherein the first intermediate grounding copper bar is connected to the second intermediate grounding copper bar through an intermediate protection gap and an intermediate high-frequency wave trap in parallel circuit, the first intermediate grounding copper bar is connected to a metal component of an optical fiber, and the second intermediate grounding copper bar is connected to the mains equipotential through an equipotential connector; The electrical equipment includes a signal transceiver and a power cabinet. The metal casing, power lines and signal lines of the electrical equipment are connected to the middle grounding copper busbar to form an equipotential structure, and a discharge channel is provided by the grounding electrode connected thereto.

2. A lightning protection grounding device for graded discharge of lightning current according to claim 1, characterized in that: The breakdown threshold of the head-end protection gap is 400-1200V, the current capacity is 50-100KA, and the waveform is 10 / 350μs. The breakdown threshold of the intermediate protection gap is 800-1600V, the current capacity is 20-50KA, and the waveform is 10 / 350μs.

3. A lightning protection grounding device for graded discharge of lightning current according to claim 1, characterized in that: The inductance of the head-end high-frequency wave trap and the middle high-frequency wave trap are 300μH~10mH respectively, and the maximum current passing therethrough is 30A; the inductance of the tail-end high-frequency wave trap is 600μH~10mH, and the maximum current passing therethrough is 15A.

4. A lightning protection grounding device for graded discharge of lightning current according to claim 1, characterized in that: An air switch is connected in series between the tail end grounding copper bar and the power supply neutral line.

5. The lightning protection grounding device for graded discharge of lightning current according to claim 1 is characterized in that: It also includes an intelligent detection module, which includes a ground resistance measurement module and a switch quantity detection module. The ground resistance measurement module is used to measure the grounding resistance of the grounding electrode corresponding to each grounding copper busbar, and the switch quantity detection module is used to detect the state of the air switch. The ground resistance measurement module and the switch quantity detection module are respectively connected to the MCU processor, and the ground resistance measurement module and the switch quantity detection module transmit the detected information to the MCU processor.

6. A lightning protection grounding device for graded discharge of lightning current according to claim 5, characterized in that: Normally closed contactors are respectively connected in series on the circuit where the head-end high-frequency wave trap is located and on the circuit where the middle high-frequency wave trap is located.

7. A method for graded discharge of lightning current using a lightning protection grounding device for graded discharge of lightning current according to any one of claims 1 to 6, characterized in that: The head-end grounding copper bar and the middle grounding copper bar are connected in parallel with a protective gap and a high-frequency wave arrester. The head-end grounding copper bar and the middle grounding copper bar are respectively connected to the earth through a grounding electrode to form a structure for graded discharge of lightning current. At the same time, a tail-end high-frequency wave arrester is connected in series between the middle grounding copper bar and the tail-end grounding copper bar, so that the high and low potentials between the head-end grounding copper bar, the middle grounding copper bar and the tail-end grounding copper bar are separated and the potentials are reduced in sequence; the head-end grounding copper bar is connected to the down conductor of the lightning rod, the tail-end grounding copper bar is connected to the working ground of the electrical equipment, and the optical fiber and the mains power are connected to the middle grounding copper bar in sequence according to the size of the direct lightning current or the induced lightning current, and graded discharge is performed according to the size of the intruding lightning current; the electrical equipment is at the same potential when the lightning current invades, and it is ensured that the working ground of the electrical equipment is always at the lowest potential level.

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