A lightning overvoltage clamping method for overhead line and lightning and vibration composite protection device

Abstract

This invention discloses a clamping method for lightning overvoltage on overhead lines and a combined lightning protection and vibration prevention device. The method includes the following steps: based on the propagation characteristics of lightning waves in a medium, a local impedance abrupt change point is set on the overhead line to alter the propagation process of the lightning wave; wherein, the local lightning wave impedance at the local impedance abrupt change point is less than the overhead line impedance; when the lightning wave reaches the impedance abrupt change point, the voltage wave undergoes negative reflection while the current wave undergoes positive reflection, and the electric field energy of the lightning wave is converted into magnetic field energy, thereby achieving the clamping of the lightning overvoltage. This invention actively clamps lightning overvoltage through impedance transformation and achieves integrated lightning protection and vibration prevention, completely eliminating the dependence of traditional protection on low grounding resistance, effectively reducing the lightning tripping rate while eliminating spatial conflicts and mutual interference between devices.

Description

Technical Field

[0001] This invention relates to the field of lightning protection technology for overhead power distribution lines, and more specifically to a clamping method for lightning overvoltage on overhead lines and a combined lightning protection and vibration damping device. Background Technology

[0002] Currently, lightning protection measures for overhead lines mainly include installing lightning protection wires (overhead ground wires), reducing the grounding resistance of towers, installing line surge arresters, and using arc-proof hardware. Among these, metal oxide surge arresters are the most widely used overvoltage protection devices. Their working principle utilizes the nonlinear volt-ampere characteristics of zinc oxide resistive elements, which exhibit a low-resistance state under lightning overvoltage, diverting the lightning current to the ground and thus limiting the voltage across the insulator string.

[0003] Furthermore, overhead conductors experience slight vibrations due to uniform, low-speed winds during continuous operation. These high-frequency, low-amplitude vibrations can cause fatigue breakage (i.e., "strand breakage") at the conductor clamp exit, severely threatening the mechanical strength of the line. Therefore, vibration dampers are typically installed on the conductors in engineering projects to absorb vibration energy.

[0004] Although the aforementioned existing technologies have solved the problems of lightning protection and vibration prevention to some extent, the following significant technical problems still exist in practical applications and long-term operation:

[0005] 1. Limitations of traditional current-discharge type lightning protection:

[0006] Most existing surge arresters use a "parallel grounding discharge" method. This method is highly dependent on the grounding resistance of the tower. In areas with high soil resistivity, such as mountains and rocky terrain, reducing grounding resistance is extremely difficult and costly. If grounding is poor, lightning current cannot be discharged smoothly, residual voltage rises, and backflashover is highly likely. In addition, surge arresters operate on the grid for extended periods, causing internal valve plates to age easily and posing an explosion hazard, resulting in a huge workload for maintenance.

[0007] 2. Lack of active control over the propagation process of lightning waves:

[0008] Current technologies primarily focus on "passive defense" after a lightning strike (such as current discharge and arc extinguishing), while neglecting the propagation characteristics of lightning waves on conductors. In fact, if the local wave impedance characteristics of the line could be altered to actively attenuate some of the lightning wave energy using the reflection principle of traveling waves, it would be a more fundamental protection approach that does not rely on grounding. However, such technologies are currently lacking in engineering applications.

[0009] 3. Separate lightning protection and vibration damping devices pose a potential "combined effect" risk:

[0010] In current engineering practice, lightning protection devices (such as surge arresters and gaps) and vibration damping devices (such as vibration dampers) are usually designed and installed independently.

[0011] Installation space conflict: Simultaneously arranging multiple hardware on a limited number of towers or conductors often leads to limited installation space and may even require modification of the tower head design.

[0012] Mutual interference: The vibration of the vibration damper may accelerate the loosening of the connection points of the lightning protection hardware; conversely, the concentrated mass of the lightning protection hardware may also change the vibration mode of the conductor, causing the vibration damper to fail.

[0013] Cost and efficiency: Separate installation increases construction procedures and material costs, and the dispersed components increase the difficulty of inspection.

[0014] Therefore, how to develop a composite device that does not rely on low grounding resistance, can actively clamp lightning overvoltage from the wave propagation mechanism, and can organically combine lightning protection and vibration prevention functions in a compact structure is a technical problem that urgently needs to be solved in the field of power transmission line protection. Summary of the Invention

[0015] In view of the above problems, the present invention is proposed to provide a clamping method for lightning overvoltage on overhead lines and a combined lightning protection and vibration prevention device to overcome or at least partially solve the above problems; by actively clamping lightning overvoltage through wave impedance transformation and realizing integrated lightning protection and vibration prevention, the traditional protection method is completely free from dependence on low grounding resistance, and the spatial conflict and mutual interference between devices are eliminated while effectively reducing the lightning tripping rate.

[0016] To achieve the above objectives, the present invention adopts the following technical solution:

[0017] In a first aspect, embodiments of the present invention provide a clamping method for lightning overvoltage on overhead lines, comprising the following steps:

[0018] Based on the propagation characteristics of lightning waves in a medium, local impedance abrupt change points are set on overhead lines to alter the propagation process of lightning waves; wherein, the local lightning wave impedance at the local impedance abrupt change point is less than the overhead line impedance.

[0019] When a lightning wave reaches the point of abrupt change in wave impedance, the voltage wave undergoes negative reflection while the current wave undergoes positive reflection. The electric field energy of the lightning wave is converted into magnetic field energy, thereby achieving clamping of lightning overvoltage.

[0020] Furthermore, the local lightning surge impedance is taken as 1 / 2 of the overhead line surge impedance value.

[0021] Furthermore, the provision of local impedance abrupt change points on overhead lines specifically includes:

[0022] An equipotential bypass resistor is connected across the overhead line; wherein the resistivity, length and cross-section of the bypass resistor are determined according to the positive sequence reactance and thermal fusing requirements of the overhead line, until the local lightning wave impedance is halved.

[0023] In a second aspect, embodiments of the present invention provide a lightning protection and vibration damping composite device for implementing the method described in any one of the first aspects, including a lightning protection component, a vibration damping component, and a clamping component;

[0024] The lightning protection component includes a linear non-inductive bypass resistor rod, the two ends of which are connected to the conductors of the overhead line at equal potentials via connectors.

[0025] The vibration damping component includes at least two vibration damping hammers, which are respectively disposed at both ends of the lightning protection component;

[0026] The clamping component is used to fix the linear non-inductive bypass resistor rod to the conductor of the overhead line.

[0027] Furthermore, the linear non-inductive bypass resistor rod is a solid cylindrical structure of equal diameter, made of sintered zinc oxide linear conductive ceramic material, and its composition is a ZnO-Al2O3-TiO2 system.

[0028] Furthermore, the cylindrical outer surface of the linear non-inductive bypass resistor is sequentially wrapped with a vulcanized silicone rubber insulating layer and a silicone rubber heat dissipation umbrella skirt.

[0029] Furthermore, both ends of the linear non-inductive bypass resistor are fixedly provided with copper-plated tin electrodes, power-connecting studs that are electrically connected to the copper-plated tin electrodes, and a protective steel cover with a through hole in the center that is adapted to the power-connecting stud.

[0030] The linear non-inductive bypass resistor, tin-plated copper electrode, power-connecting stud, and protective steel cover are on the same center line and are tightly fitted together in sequence.

[0031] Furthermore, the two anti-vibration hammers are respectively installed through the hammer through holes on the power-connecting studs at both ends of the lightning protection component, and are welded and fixed to the protective steel cover and fastening nuts;

[0032] Each vibration damping hammer head is shaped like a long-handled hammer, and the spatial angle between two vibration damping hammer heads is 60°.

[0033] Furthermore, the connector includes a copper braided strip and a C-type clamp; the copper braided strip is used to connect the grounding stud of the lightning protection component to the C-type clamp.

[0034] Furthermore, the clamping component is a split clamp consisting of two half-clamps and three sets of single-headed bolts; the half-clamps are metal plates with a double semi-circular curved structure along the longitudinal direction; the three sets of single-headed bolts fasten the two half-clamps, and after the two half-clamps are closed, they form conductor clamping holes and device clamping holes, realizing dual clamping and fixing of the overhead line conductors and the lightning protection and vibration reduction composite device.

[0035] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a clamping method for lightning overvoltage of overhead lines and a combined lightning protection and vibration damping device, which has the following beneficial effects:

[0036] This invention abandons the traditional passive protection mode of "parallel grounding discharge" for surge arresters and innovatively proposes a lightning overvoltage clamping method for overhead lines based on wave impedance transformation. By constructing a wave impedance abrupt change point on the conductor, and utilizing traveling wave propagation theory, the incident lightning wave is refracted and reflected at the wave impedance abrupt change point, thereby directly attenuating part of the lightning energy during wave propagation. This method does not rely on the grounding resistance of the tower, completely solving the problem of lightning protection failure caused by grounding difficulties in high soil resistivity areas such as high mountains and rocky areas.

[0037] This invention provides a lightning protection and vibration damping composite device, which creatively integrates a linear non-inductive bypass resistor rod (lightning protection component) and a vibration damping hammer (vibration damping component) into one unit and fixes them together with a shared clamping component. The structure is compact and synergistic, achieving a composite protection effect of "1+1>2".

[0038] This invention employs a linear, non-inductive bypass resistor as the core structural element in the lightning protection component, resulting in fast response and no risk of follow current. Furthermore, it utilizes a copper-plated tin electrode and a connecting stud at the electrical connection points, ensuring reliable contact and strong corrosion resistance; thus improving the reliability of the power grid operation. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0040] Figure 1 This is a flowchart of the clamping method for lightning overvoltage on overhead lines provided in an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram illustrating the functional relationship between the refracted wave and the incident wave provided in an embodiment of the present invention;

[0042] Figure 3This is a structural diagram of the lightning protection and vibration damping composite device provided in the embodiments of the present invention;

[0043] Figure 4 This is a schematic diagram of the lightning protection device structure provided in an embodiment of the present invention;

[0044] Figure 5 This is a three-dimensional view of the installation of the two vibration damping hammers provided in an embodiment of the present invention;

[0045] Figure 6 This is a side view of the installation of two vibration damping hammers provided in an embodiment of the present invention;

[0046] Figure 7 This is a cross-sectional view of the machining of two vibration damping hammers provided in an embodiment of the present invention;

[0047] Figure 8 This is a schematic diagram of the clamping component provided in an embodiment of the present invention. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] Example 1

[0050] This invention discloses a clamping method for lightning overvoltage on overhead lines, referring to... Figure 1 As shown, it includes the following steps:

[0051] Based on the propagation characteristics of lightning waves in a medium, local impedance abrupt change points are set on overhead lines to alter the propagation process of lightning waves; wherein, the local lightning wave impedance at the local impedance abrupt change point is less than the overhead line impedance.

[0052] When a lightning wave reaches the point of sudden change in wave impedance, the voltage wave undergoes negative reflection while the current wave undergoes positive reflection. The electric field energy of the lightning wave is converted into magnetic field energy, thereby achieving clamping of lightning overvoltage.

[0053] This embodiment is applied to the lightning protection renovation or new construction of overhead power distribution lines in mountainous and complex terrain. It utilizes the propagation characteristics of lightning waves in the medium and changes the propagation process of lightning waves on the line by setting local impedance abrupt change points, so as to partially attenuate the lightning energy and achieve the purpose of clamping lightning overvoltage.

[0054] First, regarding the propagation characteristics of lightning waves in a medium, specifically including:

[0055] During the propagation of a lightning wave (traveling wave) along a distributed-parameter line, the waveforms of the voltage and current waves remain constant, and their ratio is determined by the line's impedance. When the lightning wave reaches a point on the line where the impedance suddenly decreases, the voltage wave undergoes negative reflection while the current wave undergoes positive reflection. This means the voltage wave is weakened while the current wave is strengthened, and at this point, some of the electric field energy of the lightning wave is converted into magnetic field energy. This embodiment utilizes this principle, reducing the local impedance by bridging the line with a bypass resistor, thereby clamping off lightning overvoltage.

[0056] Secondly, the local lightning surge impedance at the point of abrupt change in local surge impedance is taken as 1 / 2 of the line surge impedance value.

[0057] Assuming that when the lightning wave reaches the point of abrupt change in local impedance, the incident voltage value is... The incident value of the current wave Voltage wave reflection value Current wave reflection value The voltage wave refraction value The refractive value of the current wave Alternatively, suppose This refers to the surge impedance value of the overhead line. Given the local lightning wave impedance value, the Peterson equation is listed at the point of abrupt change in local wave impedance as follows:

[0058]

[0059]

[0060]

[0061]

[0062]

[0063] Let the wave impedance ratio The ratio of the refracted value to the incident value of the voltage wave is obtained by solving:

[0064]

[0065] The ratio of the refracted value to the incident value of the current wave is:

[0066]

[0067] Because the voltage and current wave refraction values ​​at the local impedance abrupt change point are the actual voltage and current values ​​acting on the overhead line. (Refer to...) Figure 2As shown, the functional relationship between the refracted wave and the incident wave is illustrated; the horizontal axis represents the wave impedance ratio, and the vertical axis represents the ratio. The blue curve represents the ratio of the refracted value to the incident value of the voltage wave, which is a monotonically increasing curve; the red curve represents the ratio of the refracted value to the incident value of the current wave, which is a monotonically decreasing curve. Figure 2 It intuitively demonstrates the fundamental laws of transmission line theory: when ,Right now At this time, the system is in a matched state, and the voltage and current transfer ratios are both 1. When At this time, voltage transmission is attenuated, down to as low as 0 (negative total internal reflection); while current transmission is amplified, up to a factor of 2 (positive total internal reflection). The two curves at... The intersection point verifies the transmission characteristics under impedance matching.

[0068] Figure 2 It also reflects the fact that the local lightning surge impedance value From 0 to the overhead line surge impedance value When the voltage is constant, the refracted voltage wave is an increasing function, while the refracted current wave is a decreasing function. The smaller the impedance of the sudden change wave, the better the clamping effect of lightning overvoltage, but the more severe the current thermal effect; conversely, the clamping effect is worse, but the current increase is controllable.

[0069] Based on the ratio of the refractive value to the incident value of the voltage wave and the ratio of the refractive value to the incident value of the current wave, this embodiment provides some impedance value selections as shown in Table 1 below:

[0070] Table 1 Selection Table for Local Lightning Wave Impedance Values ​​of Lines

[0071]

[0072] While meeting the requirements for lightning overvoltage clamping, the thermal effect, electromagnetic shock, and mechanical vibration of the lightning current surge on the central conductor of the span should be balanced. Although these effects are the main direction of partial attenuation of lightning energy, it should be considered that they do not exceed the protection level of other dimensions of the line and equipment. Therefore, in this embodiment, the local lightning surge impedance value is determined to be 1 / 2 of the surge impedance of the overhead line.

[0073] Finally, equipotential bypass resistors are used on the line to halve the local lightning wave impedance.

[0074] The formula for calculating the surge impedance of an overhead line is as follows:

[0075]

[0076] in, , These represent the positive-sequence reactance and positive-sequence susceptance of the overhead line, respectively.

[0077] Since the product of positive-sequence reactance and positive-sequence susceptance of an overhead line is a constant (the square of the phase constant), when the positive-sequence reactance is reduced to half of its original value, the positive-sequence susceptance increases to twice its original value. At this time, the ratio of positive-sequence reactance to positive-sequence susceptance is 1 / 4 of its original value. Therefore, in order to achieve a local lightning surge impedance of 1 / 2 of the line surge impedance, the local positive-sequence reactance of the overhead line should be reduced to 1 / 2 of its original value.

[0078] In this embodiment, a short bypass resistor is connected across the overhead line, with a unit resistance value of R. The equivalent unit impedance of the line is:

[0079]

[0080] Taking the inductive reactance portion, we have:

[0081]

[0082] The derivation leads to:

[0083]

[0084] This embodiment calculates the positive sequence reactance of the line based on parameters such as the conductor layout dimensions and conductor radius:

[0085]

[0086] in, This refers to the geometric mean distance between phase conductors of an overhead line, in meters (m). This represents the effective radius of the overhead line conductor, in meters (m). Since the positive-sequence reactance of overhead distribution lines is generally 0.15–0.35 Ω / km, with smaller values ​​for multi-circuit lines and larger values ​​for single-circuit lines, solving the inductive reactance formula yields:

[0087]

[0088] This embodiment considers the thermal fusing effect of lightning current impulses, so the resistor cross-section should be approximately equal to the conductor cross-section, corresponding to a resistor cross-section diameter of φ20mm. Considering the commonly used FD or FR type vibration dampers for overhead distribution lines, with a length of approximately 400mm to 500mm, this embodiment sets the length of the bridging bypass resistor to 500mm. Furthermore, based on the design principle of installing one set of resistors approximately every 500 meters of tension section in the overhead distribution line, the resistivity of the bridging bypass resistor is determined as follows:

[0089]

[0090]

[0091] in, This indicates the design resistance value of the bridging bypass resistor. Indicates the design installation spacing of the bridging bypass resistor. It represents its equivalent resistance per unit length, by Determine and coordinate the implementation of wave impedance transformation. The resistivity of the bridging bypass resistor. Indicates the design length of the resistive element. This indicates the designed cross-sectional area of ​​the resistive element.

[0092] According to the material handbook, sintered zinc oxide linear conductive ceramic (ZnO-Al2O3-TiO2) meets the above resistivity requirements. The content of Al2O3 and TiO2 is about 3 mol% each. This material has the characteristics of high melting point, good thermal conductivity, high linearity and excellent weather resistance, which meets the requirements of engineering applications.

[0093] Example 2

[0094] This invention discloses a lightning protection and vibration damping composite device for implementing the overhead line lightning overvoltage clamping method in Embodiment 1, referring to... Figure 3 As shown, it includes lightning protection components, vibration damping components, and clamping components;

[0095] The lightning protection components include a linear non-inductive bypass resistor rod, the two ends of which are connected to the conductors of the overhead line through connectors at the same potential.

[0096] The vibration damping component includes at least two vibration damping hammers, which are respectively installed at both ends of the lightning protection component;

[0097] The clamping component is used to fix the linear non-inductive bypass resistor rod to the conductor of the overhead line.

[0098] This embodiment integrates a linear non-inductive bypass resistor rod with an anti-vibration hammer head into one unit, and fixes it to the conductor of the overhead line through a shared clamping component, forming a novel device with a compact structure and multiple functions.

[0099] Reference Figure 4 As shown, the lightning protection device includes a linear non-inductive bypass resistor rod, copper-plated tin electrodes at both ends of the linear non-inductive bypass resistor rod, a connecting stud electrically connected to the copper-plated tin electrodes, a protective steel cover with a through hole in the center that fits the connecting stud, an annular vulcanized silicone rubber insulation covering the linear non-inductive bypass resistor rod, a silicone rubber heat dissipation umbrella skirt covering the rubber insulation, and a copper braided strip, a C-type clamp, and a fastening nut to enable connection with the overhead line conductor and ensure the axial freedom of the linear non-inductive bypass resistor rod.

[0100] The lightning protection component in this embodiment includes a linear non-inductive bypass resistor rod. This linear non-inductive bypass resistor rod is a solid, uniform-diameter cylindrical structure with a length of 500mm. It is made of sintered zinc oxide linear conductive ceramic material, which adopts a ZnO-Al2O3-TiO2 system. Zinc oxide (ZnO) accounts for 94 mol%, and aluminum oxide (Al2O3) and titanium dioxide (TiO2) each account for 3 mol%. The resistivity is approximately [missing value]. By reducing the local positive sequence reactance of the line, the requirement that the local lightning surge impedance be reduced to half of the line surge impedance can be achieved.

[0101] In addition, the cylindrical outer surface of the linear non-inductive bypass resistor rod is sequentially wrapped with a vulcanized silicone rubber insulation layer and a silicone rubber heat dissipation skirt to resist lightning current surges, high temperatures, outdoor aging, and provide waterproofing and moisture resistance. In this embodiment, the vulcanized silicone rubber insulation layer and the silicone rubber heat dissipation skirt are formed by casting and curing around the linear non-inductive bypass resistor rod using a mold. The insulation and outer sheath skirt have the characteristics of resisting lightning current surges, high temperatures, outdoor aging, and providing waterproofing and moisture resistance.

[0102] Both ends of the linear non-inductive bypass resistor rod are fixedly provided with tin-plated copper electrodes, a stud electrically connected to the tin-plated copper electrodes, and a protective steel cover with a through hole in the center that is adapted to the stud. In this embodiment, the stud is made of copper-nickel-silicon alloy (CuNi2Si) with good combined conductivity and mechanical properties, and the protective steel cover is made of Q235 carbon steel or SUS304 stainless steel.

[0103] The copper-plated tin electrode is a circular platform shape. The bottom diameter is the same as the diameter of the linear non-inductive bypass resistor rod, and the top diameter is the same as the diameter of the connecting stud. The bottom is sintered onto the end face of the linear non-inductive bypass resistor rod with silver paste, and the top is sintered onto the end face of the connecting stud with silver paste.

[0104] The vibration damping hammers of the vibration damping component are respectively inserted through the hammer head through holes and mounted on the connecting studs at both ends of the lightning protection component, and are welded and fixed to the protective steel cover and the fastening nut. The fastening nut is located at the outermost end of the connecting stud, and a copper braided strip is connected to the connecting stud and linked to a C-type clamp. The copper braided strip and the C-type clamp are used to connect the overhead line conductors, ensuring the axial freedom of the linear non-inductive bypass resistor rod and preventing damage to the linear non-inductive bypass resistor rod due to thermal expansion and contraction of the conductors caused by the fixed connection. In this embodiment, the overall length of the lightning protection component, including the linear non-inductive bypass resistor rod, the tin-plated copper electrode, and the connecting stud, is 600mm.

[0105] The vibration damping component in this embodiment includes two vibration damping hammers, as shown in the reference... Figure 5 The image shown is a 3D diagram illustrating the installation of two vibration damping hammers; refer to... Figure 6 The image shows a side view of the two vibration damping hammers in operation; refer to... Figure 7The diagram shows a cross-sectional view of two vibration damping hammers. Each hammer is shaped like a long-handled hammer, with a larger hammerhead at one end (a circular or polygonal counterweight) and a connecting handle at the other end. The connecting handle has a through hole for the hammerhead, the size of which is adapted to the power stud. The hammerhead is a solid metal structure used to provide the inertial mass required for vibration damping. In this embodiment, the total length of the vibration damping hammer from the edge of the hammerhead to the edge of the connecting handle is 180 mm. Figure 7 The document also specifically demonstrates how the vibration damping hammerhead passes through the hammerhead through-hole into the electrical studs at both ends of the lightning protection component, and is then firmly welded to the protective steel covers and fastening nuts at both ends. Figure 6 The two vibration damping hammers are installed at a certain spatial angle, specifically 60°, to meet the frequency requirements for vibration damping in light winds.

[0106] The clamping component in this embodiment is referred to... Figure 8 As shown, the left half is a front view and the right half is a side view. It includes two half-clamps, a front and a rear, and a single-headed bolt. Each half-clamp has a bolt hole that matches the single-headed bolt. When the front and rear half-clamps are combined, they form a conductor clamping hole and a device clamping hole, which together fix the lightning protection and vibration reduction composite device on the conductor of the overhead line.

[0107] This embodiment of the clamp consists of two halves: a front half and a rear half. The halves are rectangular metal plates with a thickness of 5mm. The two halves are structurally symmetrical, and when closed, they form a complete clamping structure.

[0108] Each half-clamp is actually a metal part that has been bent twice. The upper half of each half-clamp is bent to form a semi-circular arc surface, the size of which is adapted to the conductor of the overhead line. When the two half-clamps are closed, they form a conductor clamping hole. The lower half is also bent to form a semi-circular arc surface, the size of which is adapted to the cross-sectional diameter of the silicone rubber heat dissipation umbrella skirt wrapped around the linear non-inductive bypass resistor rod. When the two half-clamps are closed, they form a device clamping hole.

[0109] This embodiment takes into account the protection requirements for conductor vibration in the wind and considers the combination of resistance rod and vibration damper into an integrated device, which can simultaneously achieve the dual functions of lightning supplementary protection and wind vibration protection.

[0110] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0111] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A clamping method for lightning overvoltage on overhead lines, characterized in that, Includes the following steps: Based on the propagation characteristics of lightning waves in a medium, local impedance abrupt change points are set on overhead lines to alter the propagation process of lightning waves; wherein, the local lightning wave impedance at the local impedance abrupt change point is less than the overhead line impedance. When a lightning wave reaches the point of abrupt change in wave impedance, the voltage wave undergoes negative reflection while the current wave undergoes positive reflection. The electric field energy of the lightning wave is converted into magnetic field energy, thereby achieving clamping of lightning overvoltage.

2. The method as described in claim 1, characterized in that, The local lightning surge impedance is taken as 1 / 2 of the overhead line surge impedance value.

3. The method as described in claim 2, characterized in that, The provision of local impedance abrupt change points on overhead lines specifically includes: An equipotential bypass resistor is connected across the overhead line; wherein the resistivity, length and cross-section of the bypass resistor are determined according to the positive sequence reactance and thermal fusing requirements of the overhead line, until the local lightning wave impedance is halved.

4. A lightning protection and vibration damping composite device, used to implement the method as described in any one of claims 1-3, characterized in that, Includes lightning protection components, vibration damping components, and clamping components; The lightning protection component includes a linear non-inductive bypass resistor rod, the two ends of which are connected to the conductors of the overhead line at equal potentials via connectors. The vibration damping component includes at least two vibration damping hammers, which are respectively disposed at both ends of the lightning protection component; The clamping component is used to fix the linear non-inductive bypass resistor rod to the conductor of the overhead line.

5. The apparatus as described in claim 4, characterized in that, The linear non-inductive bypass resistor rod is a solid cylindrical structure of equal diameter, made of sintered zinc oxide linear conductive ceramic material, and its composition is a ZnO-Al2O3-TiO2 system.

6. The apparatus as claimed in claim 5, characterized in that, The cylindrical outer surface of the linear non-inductive bypass resistor is sequentially wrapped with a vulcanized silicone rubber insulating layer and a silicone rubber heat dissipation umbrella skirt.

7. The apparatus as claimed in claim 5, characterized in that, Both ends of the linear non-inductive bypass resistor are fixedly provided with copper-plated tin electrodes, power-connecting studs that are electrically connected to the copper-plated tin electrodes, and a protective steel cover with a through hole in the center that is adapted to the power-connecting stud. The linear non-inductive bypass resistor, tin-plated copper electrode, power-connecting stud, and protective steel cover are on the same center line and are tightly fitted together in sequence.

8. The apparatus as claimed in claim 7, characterized in that, The two vibration damping hammers are respectively installed through the hammer through holes on the power connecting studs at both ends of the lightning protection component, and are welded and fixed to the protective steel cover and fastening nuts; Each vibration damping hammer head is shaped like a long-handled hammer, and the spatial angle between two vibration damping hammer heads is 60°.

9. The apparatus as claimed in claim 8, characterized in that, The connector includes a copper braided strip and a C-type clamp; the copper braided strip is used to connect the power-connecting studs of the lightning protection component to the C-type clamp.

10. The apparatus as claimed in claim 4, characterized in that, The clamping component is a split clamp consisting of two half-clamps and three sets of single-headed bolts; the half-clamps are metal plates with a double semi-circular curved structure along the longitudinal direction; the three sets of single-headed bolts fasten the two half-clamps, and after the two half-clamps are closed, they form conductor clamping holes and device clamping holes, realizing dual clamping and fixing of the overhead line conductors and the lightning protection and vibration reduction composite device.

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