A non-follow-current multi-stage gap surge protection device and overvoltage protection method

Abstract

This invention relates to the field of lightning protection technology for high-voltage transmission lines in power systems, specifically to a non-following current multi-stage gap lightning protection device and overvoltage protection method. The device includes multiple multi-stage gap bodies, a high-voltage fixing component, and a low-voltage fixing component. The two ends of each multi-stage gap body are connected to the high-voltage and low-voltage fixing components, respectively. Each multi-stage gap body includes multiple transverse electrodes. These transverse electrodes all point towards the space enclosed by the multiple multi-stage gap bodies and are arranged transversely at intervals in the longitudinal space, forming multi-stage discharge gaps between adjacent transverse electrodes. The high-voltage and low-voltage fixing components are respectively equipped with high-voltage and low-voltage electrodes. This invention employs a split-type distributed structure. The ingenious arrangement of multiple transverse electrodes forms exposed multi-stage discharge gaps, which can quickly guide the movement of the electric arc. The flashover path has stable and reliable discharge performance, effectively dissipating lightning energy and protecting the safety of the distribution network lines.

Description

Technical Field

[0001] This invention relates to the field of lightning protection technology for high-voltage transmission lines in power systems, specifically to a non-following current multi-stage gap lightning protection device and an overvoltage protection method. Background Technology

[0002] Lightning strikes on high-voltage transmission lines can directly damage power equipment and have subsequent adverse effects. In the field of lightning protection for power distribution network lines, when a line is struck by lightning and the lightning current amplitude exceeds the line's lightning withstand level, causing a flashover of the line insulation, the line will not trip because the flashover time is very short. However, after the lightning disappears, the power frequency arc generated by the line's operating voltage will continue to exist stably, which will cause the line to trip.

[0003] Existing technologies for preventing line tripping caused by lightning strikes mainly employ arc-extinguishing techniques to protect the power system. Examples include a fixed external series gap multi-chamber gap surge arrester that can be replaced under energized conditions, as disclosed in patent publication number "CN112909880A", and a series gap surge arrester disclosed in patent publication number "CN112769040A". These technologies utilize lightning overvoltage to discharge and burn within the constrained gap, causing the gas within the gap to expand rapidly, thereby extinguishing the discharge arc.

[0004] However, due to the small geometric dimensions of the transverse electrode, after multiple high-amplitude lightning strikes, there are defects such as severe burning of the transverse electrode and rupture of the arc extinguishing channel, which leads to the failure of the overvoltage protection device. The arc extinguishing effect of this type of protection device, which uses gas heating and expansion to blow away the arc within the constraint gap, is generally not very effective. Summary of the Invention

[0005] The main objective of this invention is to address the shortcomings of the aforementioned background technology and provide a safe, reliable, and more effective overvoltage protection device and overvoltage protection method for distribution network lines, specifically a non-follow-current multi-stage gap lightning protection device and overvoltage protection method.

[0006] The technical solution adopted in this invention is: a non-continuous current multi-stage gap lightning protection device, comprising multiple multi-stage gap bodies, high-voltage fixing components, and low-voltage fixing components; the high-voltage fixing components and low-voltage fixing components are respectively fixedly connected to both ends of the multi-stage gap bodies;

[0007] Each multi-stage gap body has multiple lateral electrodes arranged in parallel along the length direction of the multi-stage gap body, and the lateral electrodes of two adjacent multi-stage gap bodies are staggered vertically to form a multi-stage discharge gap.

[0008] The high-voltage fixing component and the low-voltage fixing component are respectively provided with high-voltage electrode and low-voltage electrode. The high-voltage electrode is used to generate flashover with the uppermost transverse electrode of the multi-stage gap body. The flashover conduction causes the multi-stage discharge gap to generate flashover. The flashover conduction also causes the lowermost transverse electrode of the multi-stage gap body to generate flashover with the low-voltage electrode.

[0009] Furthermore, the multi-stage gap body includes an insulating core; the transverse electrode is provided with an electrode fixing hole, and the insulating core passes through the electrode fixing hole and is connected to the transverse electrode.

[0010] Furthermore, the multi-level gap body also includes multiple umbrella skirts and a composite jacket disposed on the insulating core; an umbrella skirt is disposed between adjacent transverse electrodes on each multi-level gap body, an umbrella skirt is disposed between the uppermost transverse electrode and the high-voltage electrode on each multi-level gap body, an umbrella skirt is disposed between the bottommost transverse electrode and the low-voltage electrode on each multi-level gap body, and the longitudinal projection of each umbrella skirt in each multi-level gap body covers the adjacent transverse electrode directly below it.

[0011] Furthermore, the end of the transverse electrode furthest from the insulating core is provided with a hemispherical discharge end.

[0012] Furthermore, there are no fewer than three multi-level gap bodies, and the transverse electrodes of the three or more multi-level gap bodies are arranged in an orderly interval in the longitudinal direction, so that the discharge ends of the transverse electrodes are arranged in a spiral in space.

[0013] Furthermore, it also includes a positioning component for positioning the mounting angle of the multi-stage clearance body.

[0014] Furthermore, the multi-stage gap body has a high-pressure end clamping member and a low-pressure end clamping member at both ends for connecting with high-pressure fasteners and low-pressure fasteners, respectively.

[0015] Furthermore, all the transverse electrodes point to the same longitudinal line, and both the high-voltage electrode discharge end and the low-voltage electrode discharge end are located on the longitudinal line.

[0016] Furthermore, in the longitudinal direction, the discharge ends of two adjacent transverse electrodes are equidistant in the longitudinal cross-sectional space.

[0017] Furthermore, the discharge ends of two adjacent transverse electrodes are spaced 48–52 mm apart in the longitudinal section.

[0018] Another aspect of the present invention provides a method for overvoltage protection of power lines based on the above-mentioned lightning protection device, comprising the following steps:

[0019] S1. Connect the non-follow-current multi-stage gap surge protection device to the power system distribution network line;

[0020] S2. Lightning overvoltage is introduced through the high-voltage electrode of the non-continuous current multi-stage gap surge protection device;

[0021] S3. The high-voltage electrode flashes over with the uppermost horizontal electrode of the non-continuous current multi-stage gap lightning protection device.

[0022] S4. In the longitudinal space, flashover occurs between adjacent transverse electrodes;

[0023] S5. The bottom horizontal electrode and the low voltage electrode of the non-continuous current multi-stage gap surge protection device generate flashover. The lightning current is discharged through the electrode exposed to the air, reducing the generation of electric arc and causing the electric arc to spread out in the air. The exposed discharge arc can move out of the space enclosed by multiple multi-stage gap bodies based on the magnetic field generated by the flashover to extinguish the arc.

[0024] The advantages of this invention include: 1. This invention adopts a split-type distributed structure, and the multi-stage discharge gap formed by the ingenious arrangement of multiple transverse electrodes, combined with high-voltage and low-voltage electrodes, is more conducive to forming a reliable flashover, which can effectively reduce the probability of lightning arcing and increase the difficulty of power frequency discharge; the unconstrained gap directly exposes the discharge gap to the outdoors, which can quickly guide the lightning discharge arc to move towards the outer edge of the transverse electrode, which is more conducive to arc extinguishing; at the same time, it can effectively reduce the temperature of the transverse electrode surface and reduce the burn-out of the transverse electrode; the stable and reliable discharge performance of the multi-stage discharge gap can effectively release lightning energy and protect the safety of the distribution network line;

[0025] 2. The multi-stage gap body of the present invention includes an insulating core, which passes through the electrode fixing hole of the transverse electrode and is connected to the transverse electrode by interference fit to effectively fix the transverse electrode.

[0026] 3. Multiple umbrella skirts are set on the same multi-level gap body between adjacent transverse electrodes, and the longitudinal projection covers the transverse electrodes. Combined with the composite jacket, the uniqueness of the flashover path between two adjacent electrodes during a lightning strike can be guaranteed, thus generating a more reliable flashover.

[0027] 4. The discharge end of the transverse electrode has a hemispherical structure and a smooth spherical surface, which makes the charge distribution at the discharge end uniform, ensures that the breakdown point of lightning overvoltage is evenly distributed, and is not prone to accidental breakdown, thus avoiding the distortion of the transverse electrode caused by frequent discharge at a certain point.

[0028] 5. The transverse electrodes of three or more multi-stage gap bodies are arranged in an orderly interval in the longitudinal direction, so that the discharge ends of the transverse electrodes are arranged in a spiral, which is more conducive to the outward expansion of the arc, lengthens the arc resistance, and is more conducive to arc extinguishing; avoid the need to add more transverse electrodes to ensure the arc extinguishing effect when using two multi-stage gap bodies, which would lengthen the length of the multi-stage gap body and make installation and maintenance difficult.

[0029] 6. The positioning components facilitate the precise installation of the multi-stage gap body, avoiding deviations between the orientation of the lateral electrodes of the installed multi-stage gap body and the design direction;

[0030] 7. The multi-stage clearance body can be connected and fixed to the high-pressure fastener and the low-pressure fastener by using high-pressure fasteners and low-pressure fasteners;

[0031] 8. The discharge terminals are evenly spaced in the longitudinal section, which facilitates the generation of stable and reliable flashover;

[0032] 9. When the discharge ends of two adjacent transverse electrodes are spaced 48-52 mm apart in the longitudinal section, a stable and reliable flashover can be guaranteed to discharge lightning current, and it is not easy to generate an electric arc.

[0033] 10. The overvoltage protection method of the present invention is applicable to various high voltage distribution lines such as 10kV and 35kV, and can protect the safety of distribution lines with lightning impulse action voltage values ​​up to 240kV.

[0034] The non-following current multi-stage gap lightning protection device of the present invention is suitable for overvoltage protection of power distribution network lines. It adopts an open structure of transverse electrode gap, which can quickly guide the lightning discharge arc to move outward of the transverse electrode, effectively reducing the temperature of the transverse electrode surface and reducing the burn-out of the transverse electrode. The ingenious arrangement of the transverse electrodes in the non-following current multi-stage gap structure ensures reliable flashover of lightning impulses, reduces the arc-building rate of power frequency arcs, increases the difficulty of power frequency discharge, and improves the reliability of line safe operation, making it highly valuable for promotion. Attached Figure Description

[0035] Figure 1 : A schematic diagram of the structure of the non-continuous current multi-stage gap lightning protection device of the present invention;

[0036] Figure 2 : A schematic diagram of the structure of the multi-stage gap body of the present invention;

[0037] Figure 3 : Schematic diagram of the transverse electrode structure of the multi-level gap body of the present invention;

[0038] Figure 4 : Schematic diagram of the high-pressure fastener structure of the present invention;

[0039] Figure 5 : Schematic diagram of the low-pressure fastener structure of the present invention;

[0040] Figure 6 : A schematic diagram of the spatial relative positions of the electrodes in the cross-section of the multi-level gap body of the present invention;

[0041] Figure 7 : A schematic diagram of the spatial relative positions of the electrodes in the longitudinal section of the multi-level gap body of the present invention;

[0042] Figure 8 : Schematic diagram of the installation of the non-continuous current multi-stage gap lightning protection device of the present invention;

[0043] Wherein: 1—low-pressure fixing component, 11—low-pressure fastening hole, 12—low-pressure electrode, 13—low-pressure hardware fixing hole, 14—low-pressure mounting hole, 2—multi-stage gap body, 20—multi-stage discharge gap, 21—transverse electrode, 211—discharge end, 212—electrode fixing hole, 22—high-pressure end clamping component, 221—first threaded hole, 222—locating pin, 23—umbrella skirt, 24—composite outer jacket, 25—low-pressure end clamping component, 251—second threaded hole, 3—high-pressure fixing component, 31—high-pressure fastening hole, 32—high-pressure electrode, 33—high-pressure mounting hole, 4—insulating core, 5—fastening nut. Detailed Implementation

[0044] The embodiments of the present invention are described in detail below, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary. The drawings are not drawn to scale and are intended to explain the content of the present invention, and should not be construed as limiting the present invention.

[0045] In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified; the orientation or positional relationship indicated by "longitudinal", "lateral", etc. as described herein is based on the orientation or positional relationship shown in the accompanying drawings.

[0046] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0047] This invention relates to a non-follow-current multi-stage gap lightning protection device, specifically, as follows: Figure 1-8As shown, it includes multiple multi-stage gap bodies 2, high-voltage fixing components 3, and low-voltage fixing components 1. The high-voltage fixing components 3 and low-voltage fixing components 1 are connected to both ends of each multi-stage gap body 2. Each multi-stage gap body 2 includes multiple rod-shaped transverse electrodes 21 arranged side-by-side along the length of the multi-stage gap body 2. The multiple transverse electrodes 21 on the same multi-stage gap body 2 point in the same direction. The transverse electrodes 21 on different multi-stage gap bodies 2 all point into the space enclosed by the multiple multi-stage gap bodies 2, and are staggered vertically in the longitudinal space, so that a flashover path between the transverse electrodes 21 is a diagonal line in space (with an angle to the horizontal and vertical directions), and the multiple flashover paths are connected in a spiral shape in space. Preferably, any two transverse electrodes 21 on the same multi-stage gap body 2 are not adjacent in the longitudinal arrangement of all transverse electrodes 21 (i.e., other multi-stage gap bodies are provided between adjacent transverse electrodes 21 on the same multi-stage gap body 2). The transverse electrodes 21 of the 2 are arranged vertically and vertically to form a multi-stage discharge gap 20 between adjacent transverse electrodes 21 (the multi-stage discharge gap 20 includes air gaps 2A, 2B, and 2C); preferably, multiple multi-stage gap bodies 2 form a regular polygon, and the transverse electrodes 21 all point to the central axis inside the space; the high-voltage fixing component 3 and the low-voltage fixing component 1 are respectively provided with a high-voltage electrode 32 and a low-voltage electrode 12. The high-voltage electrode 32 is used to generate flashover with the uppermost transverse electrode 21 of the multiple multi-stage gap bodies 2, and to generate flashover in the multi-stage discharge gap 20 through flashover conduction, and to generate flashover between the bottommost transverse electrode 21 of the multi-stage gap body 2 and the low-voltage electrode 12 through flashover conduction; when connected to the power system distribution network line, the high-voltage fixing component 3 is used to connect with the overhead distribution network circuit; the high-voltage fixing component 3 and the low-voltage fixing component 1 are made of cast iron material with passivated surface treatment.

[0048] In a further embodiment, this embodiment describes the above-mentioned multi-level gap body 2, specifically, as follows: Figure 2 As shown, the multi-stage gap body 2 also includes a columnar insulating core 4; the aforementioned transverse electrode 21 is provided with an electrode fixing hole 212, and the insulating core 4 passes through the electrode fixing hole 212 and is interference-fitted with the transverse electrode 21, so that the multiple transverse electrodes 21 on the same insulating core 4 have the same orientation. The insulating core 4 can fix multiple transverse electrodes 21 and also serves as a support. The insulating core 4 can be of other shapes and structures, as long as it can be used to fix the transverse electrodes 21.

[0049] In the preferred embodiment, the multi-level gap body 2 described above has been optimized, specifically, as follows: Figure 1-2As shown, the multi-stage gap body 2 also includes multiple umbrella skirts 23 and a composite outer jacket 24 disposed on the insulating core 4; the umbrella skirts 23 are disposed on the insulating core; an umbrella skirt 23 is disposed between adjacent transverse electrodes 21 on each multi-stage gap body 2, an umbrella skirt 23 is disposed between the uppermost transverse electrode 21 and the high voltage electrode 32 on each multi-stage gap body 2, and an umbrella skirt 23 is disposed between the bottommost transverse electrode 21 and the low voltage electrode 12 on each multi-stage gap body 2. The longitudinal projection of each umbrella skirt 23 in each multi-stage gap body 2 covers the adjacent transverse electrode 21 directly below it, and the arrangement of the umbrella skirt 23 preserves the flashover channel between the transverse electrode 21 and the longitudinally adjacent electrodes (transverse electrode 21, high voltage electrode 32, low voltage electrode 12). Through the composite outer jacket 24 and the umbrella skirts 23, the uniqueness of the flashover path between two adjacent electrodes during a lightning strike is ensured, thereby generating a more stable and reliable flashover, and also protecting the transverse electrode 21 from being clean; the composite outer jacket 24, formed by the silicone rubber vulcanization process, can also protect the insulating core 4 and other components from being damaged by lightning strikes.

[0050] In other embodiments, this embodiment optimizes the aforementioned lateral electrode 21, specifically, as follows: Figure 1-3 As shown, the end of the transverse electrode 21 furthest from the insulating core 4 is provided with a hemispherical discharge end 211. Both the high-voltage electrode 32 and the low-voltage electrode 12 include discharge ends 211, meaning the surface of the discharge end 211 is a smooth spherical surface. This ensures uniform charge distribution at the discharge end 211, guaranteeing a uniform distribution of lightning overvoltage breakdown points, reducing the likelihood of accidental breakdown, and preventing frequent discharges at a single point that could cause deformities in the transverse electrode 21. Preferably, the diameter of the hemispherical structure of the discharge end 211 of the transverse electrode 21 is 8–12 mm. The transverse electrode 21 is made of a conductive material with high specific heat capacity and precision-machined using a mold, which effectively reduces the temperature rise of the transverse electrode 21 and promotes rapid dissipation of arc heat. Furthermore, the discharge end 211 can be machined into a hemispherical, conical, or other shape; the electrode fixing hole 212 can be circular, rectangular, or other shapes.

[0051] In the preferred embodiment, the number of the multi-level gap bodies 2 has been optimized, specifically, as follows: Figure 1 and Figure 8 As shown, there are no fewer than three multi-stage gap bodies 2, and the transverse electrodes 21 of the multi-stage gap bodies 2 are arranged in an orderly interval in the longitudinal direction, so that the discharge ends 211 of all transverse electrodes 21 are arranged in a spiral in three-dimensional space. Even if the flashover path is spiral, the spiral shape can be selected to rotate clockwise or counterclockwise downwards according to the design. Compared with straight and Z-shaped flashover paths, the spiral flashover path lengthens the arc resistance, which is conducive to the outward expansion of the arc and is more conducive to arc extinguishing. Preferably, there are three multi-stage gap bodies 2 arranged in a regular triangular prism structure, and all transverse electrodes 21 point to the central axis of the regular triangular prism.

[0052] In the preferred embodiment, this embodiment optimizes the lightning protection device, specifically, as follows: Figure 2 As shown, the device also includes a positioning component for positioning the installation angle of the multi-stage gap body 2. The positioning component includes a positioning pin 222 and a positioning hole that cooperates with the positioning pin 222 for positioning. The positioning pin 222 is set at the top or bottom of the multi-stage gap body 2. The high-pressure fixing component 3 or the low-pressure fixing component 1 is provided with a positioning hole corresponding to the positioning pin 222 (corresponding to the position of the positioning pin 222). When installing the multi-stage gap body 2, the positioning pin 222 is inserted into the positioning hole, so that the pointing direction of the transverse electrode 21 of the multi-stage gap body 2 is unique, which facilitates the precise positioning and installation of the multi-stage gap body 2 and avoids the deviation of the orientation of the transverse electrode 21 of the installed multi-stage gap body 2 from the design direction.

[0053] In a further embodiment, this embodiment describes the connection method of the above-mentioned multi-level gap body 2, specifically, as follows: Figure 2 , Figure 4 , Figure 5 and Figure 8 As shown, the multi-stage gap body 2 has a high-pressure end clamping member 22 and a low-pressure end clamping member 25 at both ends for connection with the high-pressure fixing member 3 and the low-pressure fixing member 1, respectively; the high-pressure fixing member 3 has multiple high-pressure fastening holes 31 and high-pressure mounting holes 33, and the top of the high-pressure end clamping member 22 has a first threaded hole 221. The multi-stage gap body 2 is threadedly connected to the high-pressure end clamping member 22 through the high-pressure fastening hole 31 by a first spiral fastener; the high-pressure electrode 32 is connected to the high-pressure mounting hole 33 by a clamping process; one side of the high-pressure fixing member 3 is connected by a fastening nut 5 and a guide The wire connector is fixedly connected to the high-voltage distribution network line; the low-voltage fastener 1 includes a low-voltage fastening hole 11, a low-voltage mounting hole 14 and a low-voltage fitting fixing hole 13. The bottom end of the low-voltage end clamping member 25 is provided with a second threaded hole 251. The multi-stage gap body 2 is threadedly connected to the low-voltage end clamping member 25 through the low-voltage fastening hole 11 by a second spiral fastener. The low-voltage electrode 12 is connected to the low-voltage mounting hole 14 by a clamping process. The low-voltage fastener 1 is fixedly connected to the fittings that support this lightning protection device through the low-voltage fitting fixing hole 13 by a third spiral fastener.

[0054] In the preferred embodiment, the arrangement of the lateral electrode 21 is optimized, specifically, as follows: Figure 1 and Figure 6 As shown, all the transverse electrodes 21 point to the same longitudinal line within the space enclosed by the multi-level gap body 2. The discharge end 211 of the high-voltage electrode 32 and the discharge end 211 of the low-voltage electrode 12 are both located on the longitudinal line facing the transverse electrodes 21.

[0055] In a further embodiment, the arrangement of the lateral electrode 21 described above has been optimized, specifically, as follows: Figure 7As shown, in the longitudinal direction (in the longitudinal space of all transverse electrodes 21), the discharge ends 211 of two adjacent transverse electrodes 21 are equally spaced in the longitudinal cross-sectional space (i.e., Figure 7 In the case of H1=H2), it is preferable that the longitudinal spacing of all discharge terminals 211 of the high-voltage electrode 32, the low-voltage electrode 12 and the transverse electrode 21 is equal, so that the flashover is more stable and reliable and conducive to the discharge of lightning energy.

[0056] In the preferred embodiment, the longitudinal spacing of the transverse electrodes 21 is described in detail, specifically as follows: Figure 7 As shown, in the longitudinal direction, the distance between the discharge ends 211 of two adjacent transverse electrodes 21 in the longitudinal cross-sectional space is any value between 45 and 55 mm, which can be 46, 47, 48, 49, 51, 52, 53, or 54 mm. In multiple tests, when the distance between the discharge ends 211 of adjacent transverse electrodes 21 in the longitudinal space is about 50 mm, it can ensure reliable flashover and lengthen the arc resistance, avoiding the problem of arcing when the distance is too close and unstable flashover when the distance is too far, thus preventing the discharge of lightning energy.

[0057] This invention also provides an overvoltage protection method for power lines using the above-mentioned lightning protection device, applicable to various high-voltage distribution network lines such as 10kV and 35kV, and capable of protecting distribution network lines with lightning impulse action voltage values ​​up to 240kV. The method includes the following steps:

[0058] S1. Connect the non-continuous current multi-stage gap lightning protection device to the power system distribution network line, including connecting the high voltage electrode 32 to the overhead distribution network line circuit, and connecting the low voltage electrode 12 to the direct grounding system or the non-direct grounding system circuit according to the design.

[0059] S2. Lightning overvoltage is introduced through the high-voltage electrode 32 of the non-continuous current multi-stage gap surge protection device;

[0060] S3. The high-voltage electrode 32 flashes over with the uppermost horizontal electrode 21 of the non-continuous current multi-stage gap lightning protection device.

[0061] S4. In the longitudinal space of all transverse electrodes 21, flashover occurs between adjacent transverse electrodes 21.

[0062] S5. The bottom horizontal electrode 21 and the low voltage electrode 12 of the non-continuous current multi-stage gap lightning protection device generate flashover. The lightning current is discharged through the electrode exposed to the air, reducing the generation of electric arc and causing the electric arc to spread out in the air. The exposed discharge arc can move perpendicularly to the magnetic field generated by the flashover to the outside of the space enclosed by multiple multi-stage gap bodies 2 to extinguish the arc.

[0063] The working principle of the above-mentioned non-continuous current multi-stage gap lightning protection device is explained below.

[0064] In the field of lightning protection for power distribution lines, when a line is struck by lightning and the lightning current amplitude exceeds the line's lightning withstand level, causing a flashover of the line insulation, the line will not trip because the flashover time is very short. However, if the power frequency arc generated by the line's operating voltage continues to exist stably after the lightning disappears, it is easy to cause the line to trip.

[0065] The probability of a lightning flashover transforming into a power frequency arc depends on the average electric field strength in the arc path, as well as the instantaneous value of the power frequency voltage at the moment of flashover and the deionization conditions. Based on experiments and operational experience, the probability of a lightning flashover transforming into a stable power frequency arc is called the arc-building rate, denoted by η.

[0066] It can be calculated using the following formula.

[0067] η = 4.5E 0.75 — 14 (%)

[0068] In the formula, E is the average operating voltage gradient of the insulator string [kV (RMS) / m];

[0069] For neutral-point directly grounded systems:

[0070]

[0071] For neutral point not directly grounded systems:

[0072]

[0073] For a neutral-point directly grounded system with an iron crossarm, ue represents the line rated voltage [kV (RMS)]; l j The flashover distance of the insulator string is (m).

[0074] For a neutral-point ungrounded system, a single-phase flashover will not cause a trip. Only when the second phase conductor flashes over will it cause a phase-to-phase flashover and trip. In the above formula, the line voltage and the phase-to-phase insulation length are given.

[0075] Practice has shown that when E≤6[kV(effective value) / m], the arc-building rate is very small, and it can be approximated that the arc-building rate η=0.

[0076] Based on the operating voltage of the distribution network lines and E≤6[kV(RMS) / m], the flashover distance designed by the non-following current multi-stage gap surge protection device ensures reliable flashover of the above-mentioned lines under lightning impact and reduces the arc-building rate of power frequency arcs.

[0077] The high-voltage fixing component 3 of the non-follow-current multi-stage gap surge protector is fixed to the overhead distribution network line by a clamp through a connecting wire. When the line is subjected to lightning overvoltage, the high-voltage fixing component 3 leads the lightning overvoltage to the high-voltage electrode 32, causing the multi-stage discharge gap 20 on the multi-stage gap body 2 to break down and discharge. The lightning overvoltage causes the transverse electrode 21 on the multi-stage gap body 2 to flash over rapidly in sequence. The multi-stage gap body 2 then flashes over with the low-voltage electrode 12 on the low-voltage fixing component 1, thus discharging the lightning current.

[0078] The discharge arc generates a longitudinal magnetic field along the spiral path (the flashover path between the discharge ends 211). The arc current is inclined in space and can move rapidly outside the space enclosed by multiple multi-level gap bodies in the longitudinal magnetic field, promoting arc extinguishing and reducing the temperature of the electrode discharge surface. The design of the transverse electrode 21 with high specific heat capacity is more conducive to reducing the temperature rise of the electrode during overvoltage arcing, allowing the heat generated by the arc to dissipate and reducing the burn-off of the transverse electrode 21. The spherical structure of the discharge end 211 of the transverse electrode 21 can avoid malfunctions caused by sharp discharge at the corners. The metal gap structure formed between the transverse electrodes 21 reduces the temperature of the discharge arc, the discharge arc plasma is in a deionized state, and the discharge arc resistance is very high, making the arc easier to extinguish. This can ensure stable release when the transmission line is subjected to lightning overvoltage, protecting the safety of the transmission line.

[0079] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A non-following current multi-stage gap lightning protection device, characterized in that: It includes multiple multi-stage gap bodies (2), high-pressure fasteners (3) and low-pressure fasteners (1); the high-pressure fasteners (3) and low-pressure fasteners (1) are respectively fixedly connected to both ends of the multi-stage gap bodies (2); Each multi-level gap body (2) includes multiple transverse electrodes (21) arranged in parallel along the length direction of the multi-level gap body (2). All transverse electrodes (21) point to the interior of the space enclosed by the multiple multi-level gap bodies (2). The transverse electrodes (21) of two adjacent multi-level gap bodies (2) are staggered vertically to form a multi-level discharge gap (20). High-voltage fixing component (3) and low-voltage fixing component (1) are respectively provided with high-voltage electrode (32) and low-voltage electrode (12). The high-voltage electrode (32) is used to generate flashover with the uppermost transverse electrode (21) in the multi-level gap body (2). The multi-level discharge gap (20) is generated by flashover conduction. The lowermost transverse electrode (21) in the multi-level gap body (2) is also generated by flashover conduction with the low-voltage electrode (12).

2. The non-following current multi-stage gap lightning protection device as described in claim 1, characterized in that: The multi-stage gap body (2) includes an insulating core (4); the transverse electrode (21) is provided with an electrode fixing hole (212), and the insulating core (4) passes through the electrode fixing hole (212) and is connected to the transverse electrode (21).

3. The non-following current multi-stage gap lightning protection device as described in claim 2, characterized in that: The multi-level gap body (2) also includes multiple umbrella skirts (23) and a composite jacket (24) disposed on the insulating core (4); an umbrella skirt (23) is disposed between adjacent transverse electrodes (21) on each multi-level gap body (2), an umbrella skirt (23) is disposed between the uppermost transverse electrode (21) and the high voltage electrode (32) of each multi-level gap body (2), an umbrella skirt (23) is disposed between the bottommost transverse electrode (21) and the low voltage electrode (12) of each multi-level gap body (2), and the longitudinal projection of each umbrella skirt (23) in each multi-level gap body (2) covers the adjacent transverse electrode (21) directly below it.

4. A non-following current multi-stage gap lightning protection device as described in any one of claims 1 to 3, characterized in that: The transverse electrode (21) has a hemispherical discharge end (211) at the end away from the insulating core (4).

5. A non-following current multi-stage gap lightning protection device as described in claim 4, characterized in that: There are no fewer than three multi-level gap bodies (2). The transverse electrodes (21) of the three or more multi-level gap bodies (2) are arranged in an orderly interval in the longitudinal direction, so that the discharge ends (211) of the transverse electrodes (21) are arranged in a spiral in space.

6. A non-following current multi-stage gap lightning protection device as described in claim 4, characterized in that: It also includes a positioning component for positioning the mounting angle of the multi-stage gap body (2).

7. A non-following current multi-stage gap lightning protection device as described in claim 4, characterized in that: The multi-stage gap body (2) has a high-pressure end clamping member (22) and a low-pressure end clamping member (25) at both ends for connecting with high-pressure fasteners and low-pressure fasteners, respectively.

8. A non-following current multi-stage gap lightning protection device as described in claim 4, characterized in that: In the longitudinal direction, the discharge ends (211) of two adjacent transverse electrodes (21) are equally spaced in the longitudinal cross-section space.

9. A non-following current multi-stage gap lightning protection device as described in claim 8, characterized in that: The discharge ends (211) of two adjacent transverse electrodes (21) are spaced 48-52 mm apart in the longitudinal section.

10. A method for overvoltage protection of power lines based on the non-follow-current multi-stage gap surge protection device according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Connect the non-follow-current multi-stage gap surge protection device to the power system distribution network line; S2, lightning overvoltage is introduced through the high voltage electrode (32) of the non-continuous current multi-stage gap lightning protection device; S3, the high-voltage electrode (32) flashes over with the uppermost horizontal electrode (21) of the non-continuous current multi-stage gap lightning protection device; S4. In the longitudinal space, flashover occurs between adjacent transverse electrodes (21); S5. The bottom horizontal electrode (21) and the low voltage electrode (12) of the non-continuous multi-stage gap lightning protection device generate flashover. The lightning current is discharged through the electrode exposed to the air, reducing the generation of electric arc and causing the electric arc to spread out in the air. The exposed discharge arc can move to the outside of the space enclosed by multiple multi-stage gap bodies (2) based on the magnetic field generated by the flashover to extinguish the arc.

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