Direct lightning damage prevention method and device for cement pole tower of distribution line

Abstract

The invention discloses a direct lightning damage prevention method and device for a distribution line cement pole tower, and the method comprises the steps: carrying out the breakdown test of a cement test block of the distribution line cement pole tower, and obtaining the breakdown voltage characteristics of the cement test block; performing a large-current through-current test on internal steel bars of the distribution line cement pole tower to obtain thermal collapse current characteristics of the internal steel bars; establishing a direct lightning electrical simulation model of the distribution line cement pole tower according to the breakdown voltage characteristic and the thermal collapse current characteristic; and based on the direct lightning electrical simulation model, selecting the direct lightning damage prevention device for the cement tower of the distribution line and the electrical parameters of the direct lightning damage prevention device. The beneficial effects of the invention are that the cement test block is subjected to a breakdown test and the internal reinforcing steel bar is subjected to a large-current through-flow test, so that accurate breakdown voltage characteristics and thermal collapse current characteristics are obtained, the lightning protection effect is improved, and economic loss caused by lightning stroke is reduced at the same time; by establishing a comprehensive direct lightning electrical simulation model, the simulation accuracy is improved, and the lightning protection design is closer to the actual situation.

Description

Technical Field

[0001] The invention relates to the technical field of power distribution line fault management, in particular to a method and device for preventing direct lightning damage to a cement pole tower of a power distribution line. Background Art

[0002] Distribution line towers are an important part of distribution lines. In sections or substations where lightning strikes are frequent, distribution line towers are very susceptible to direct lightning strikes, which can cause breakdown and peeling of the tower cement layer, resulting in damage to the tower and pole collapse accidents, seriously affecting the power supply reliability of the distribution line. However, traditional methods for preventing and controlling direct lightning strikes on distribution line towers have been relatively neglected. Existing prevention and control methods (such as installing artificial grounding electrodes) do not take into account the insulation tolerance performance of the actual distribution network line tower cement layer and the thermal collapse performance of the internal steel bars, resulting in the existing technical means being difficult to effectively adapt to the actual distribution network line direct lightning prevention and control needs.

[0003] Based on this, in order to solve the above problems, it is necessary to conduct in-depth research on the methods of direct lightning prevention and control of distribution network line towers, fully consider the direct lightning conditions in the area where the towers are located and the electrical performance of the cement towers, perform simulation and electrical parameter selection in the electrical simulation model, and realize differentiated direct lightning prevention and control of distribution network lines, so as to effectively ensure the power supply reliability of distribution network lines. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above problems or problems existing in the prior art, the present invention is proposed.

[0006] Therefore, the object of the present invention is to provide a method and device for preventing direct lightning damage to cement pole towers of distribution lines, which can.

[0007] To solve the above technical problems, the present invention provides the following technical solutions: a method for preventing direct lightning damage to cement towers of distribution lines, comprising performing a breakdown test on cement test blocks of cement towers of distribution lines to obtain the breakdown voltage characteristics of the cement test blocks; performing a large current flow test on the internal steel bars of cement towers of distribution lines to obtain the thermal collapse current characteristics of the internal steel bars; establishing a direct lightning electrical simulation model of cement towers of distribution lines according to the breakdown voltage characteristics and the thermal collapse current characteristics; and selecting a direct lightning damage prevention device for cement towers of distribution lines and its electrical parameters based on the direct lightning electrical simulation model.

[0008] As a preferred solution of the method for preventing direct lightning damage to cement pole towers of distribution lines of the present invention, the breakdown test of cement test blocks of cement pole towers of distribution lines comprises:

[0009] Clamp the contact electrode on the thickness layer of the cement test block of the distribution line cement tower, and slowly increase the voltage until the test block has internal penetration breakdown;

[0010] Record the voltage value when the test block breaks down;

[0011] Repeat the above steps for several times to obtain a set of breakdown voltage value sequence data;

[0012] The median of the breakdown voltage value sequence data is taken as the breakdown voltage value of the cement test block of the distribution line cement tower with a probability of 50%.

[0013] As a preferred solution of the method for protecting a cement tower of a power distribution line from direct lightning damage of the present invention, the method comprises: performing a large current flow test on the steel bars inside the cement tower of the power distribution line, comprising:

[0014] Ground one end of the steel bar inside the cement tower of the distribution line, and apply a surge current with a 2.6 / 50μs lightning current waveform from the other end;

[0015] Starting from 0kA, the current is applied in increments of 1kA until obvious thermal collapse damage occurs to the cement layer inside the cement tower of the distribution line;

[0016] Record the current value that causes thermal collapse in the above steps;

[0017] Repeat the above steps for several times to obtain a set of thermal collapse current value sequence data;

[0018] The median of the thermal breakdown current value series data is taken as the thermal breakdown current value of the steel bars inside the cement tower of the distribution line.

[0019] As a preferred solution of the method for protecting distribution line cement towers from direct lightning damage of the present invention, a direct lightning electrical simulation model of distribution line cement towers is established according to the breakdown voltage characteristics and the thermal collapse current characteristics. The direct lightning electrical simulation model includes a lightning current model, a wave impedance model, a tower volume resistance model, a tower internal inductance model and a tower natural grounding impact grounding impedance model.

[0020] As a preferred solution of the method for protecting distribution line cement towers from direct lightning damage of the present invention, the amplitude of the lightning current model is the lightning current amplitude with a probability of 90% within a circular range of 2km in diameter at the installation location of the distribution line cement tower, and the lightning current waveform parameter is 2.6 / 50μs.

[0021] As a preferred solution of the method for protecting cement towers from direct lightning damage in distribution lines of the present invention, the wave impedance model value is 150Ω, the tower volume resistance model value is 300MΩ, the tower internal inductance model value is 12μH, and the tower natural grounding impulse grounding impedance model value is 10Ω.

[0022] In order to solve the above technical problems, the present invention provides the following technical solutions: a device for preventing direct lightning damage to cement towers of distribution lines, including a method for preventing direct lightning damage to cement towers of distribution lines; and a first unit is a tower horizontal bar separately grounded down conductor unit, including:

[0023] A first inductance element connected to the tower crosspiece, a grounding resistance element connected in series with the first inductance element, and a grounding down conductor for connecting the grounding resistance element to the ground;

[0024] The second unit: The unit where the tower crosspiece is connected to the internal steel bars through an inductor element, including:

[0025] A second inductor connected to the tower crosspiece, used to connect the second inductor to the connection resistance of the internal steel bars;

[0026] Among them, the first unit and the second unit are selected according to the simulation results of the direct lightning electrical simulation model of the distribution line cement tower, and the direct lightning electrical simulation model is established based on the breakdown voltage characteristics of the cement test block of the distribution line cement tower and the thermal collapse current characteristics of the internal steel bars.

[0027] As a preferred solution of the device for preventing direct lightning damage to cement pole towers of distribution lines of the present invention, the device for preventing direct lightning damage to cement pole towers of distribution lines comprises:

[0028] A simulation model of the first unit is established, in which the inductance element is set to 2.0 μH and the grounding resistance element is an adjustable element;

[0029] Adjust the grounding resistance element in the direct lightning electrical simulation model and observe the voltage between the tower crosspiece and the internal steel bars;

[0030] If the grounding resistance is greater than 0.2Ω and the voltage extreme value between the tower crosspiece and the internal steel bar does not exceed the obtained breakdown voltage value, the first unit is selected; otherwise, the second unit is selected.

[0031] As a preferred solution of the device for preventing direct lightning damage to cement pole towers of distribution lines of the present invention, the device for preventing direct lightning damage to cement pole towers of distribution lines further comprises:

[0032] A simulation model of the second unit was established, in which the connection resistance between the tower crosspiece and the internal steel bar was 0.01Ω;

[0033] In the direct lightning electrical simulation model, the inductance of the inductor is increased to observe the current flowing into the ground by the internal steel bars;

[0034] When the internal steel bar entering-ground current is less than the obtained thermal breakdown current value, the inductance of the inductor element in this state is used as the value of the inductor element in the second unit.

[0035] As a preferred solution of the device for protecting cement towers from direct lightning damage of distribution lines of the present invention, when the first unit is selected:

[0036] The inductance value of the first inductor element is 2.0 μH, and the grounding resistance element is an adjustable resistor, and its resistance value is greater than 0.2Ω;

[0037] When selecting Unit 2:

[0038] The inductance value of the second inductor is determined through simulation, so that the internal steel bar grounding current is smaller than the thermal collapse current value of the steel bars inside the cement tower of the distribution line, and the resistance value of the connection resistor is 0.01Ω.

[0039] Beneficial effects of the present invention: by performing a breakdown test on a cement test block and a large current flow test on an internal steel bar, the present invention obtains accurate breakdown voltage characteristics and thermal collapse current characteristics, thereby ensuring the accuracy and reliability of the lightning protection design, improving the lightning protection effect, and reducing the economic losses caused by lightning strikes; by establishing a comprehensive direct lightning electrical simulation model, including multiple key parameters such as lightning current, wave impedance, and tower volume resistance, the accuracy of the simulation is improved, the lightning protection design is closer to the actual situation, the design cost of the lightning protection device is reduced, and the safety performance of the distribution line is improved; by providing two complementary direct lightning damage protection devices and selecting and optimizing parameters based on the simulation results, the differentiated design of lightning protection measures is realized, and the applicability and effectiveness of the lightning protection device are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0041] Figure 1 The figure is a schematic diagram of the overall process of the method for protecting cement pole towers of distribution lines from direct lightning damage.

[0042] Figure 2 This is a schematic diagram of the structure of the device for protecting cement pole towers from direct lightning damage in distribution lines.

[0043] Figure 3This is a schematic diagram of the first unit structure of the device for protecting cement pole towers from direct lightning damage on distribution lines.

[0044] Figure 4 This is a schematic diagram of the second unit structure of the device for protecting cement pole towers from direct lightning damage on distribution lines. DETAILED DESCRIPTION

[0045] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0046] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0047] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0048] Example 1

[0049] Reference Figure 1-2 , which is the first embodiment of the present invention, provides a method for protecting a distribution line cement tower from direct lightning damage, which includes a method for performing a breakdown test on a cement test block of a distribution line cement tower.

[0050] Specifically, S1: performing a breakdown test on a cement test block of a distribution line cement tower to obtain a breakdown voltage characteristic of the cement test block;

[0051] S2: Conduct a large current flow test on the internal steel bar M1 of the distribution line cement tower to obtain the thermal collapse current characteristics of the internal steel bar M1;

[0052] S3: Establish an electrical simulation model of direct lightning strikes on cement towers of distribution lines based on breakdown voltage characteristics and thermal collapse current characteristics;

[0053] S4: Select the lightning damage protection device for distribution line cement towers and its electrical parameters based on the lightning electrical simulation model.

[0054] It should be noted that a breakdown test was conducted on the cement test block of the distribution line cement tower, and the breakdown voltage values ​​of the cement test block of the distribution line cement tower were collected multiple times to obtain the breakdown voltage value of the cement test block of the distribution line cement tower with a probability of 50%. A large current flow test was conducted on the steel bar M1 inside the distribution line cement tower to obtain the thermal collapse current value inside the distribution line cement tower. According to the breakdown voltage value of the cement test block of the distribution line cement tower with a probability of 50% and the thermal collapse current value inside the distribution line cement tower, a direct lightning electrical simulation model for the distribution line cement tower was established. According to the direct lightning electrical simulation model and simulation conclusions of the distribution line cement tower, the distribution line cement tower anti-direct lightning damage device and the corresponding electrical parameters were selected.

[0055] Preferably, its material should be consistent with the material of the distribution line cement tower body, the test block should be a test block module with a length of 70±2mm, a width of 50±2mm, and a thickness of 42±1mm, and the number of test blocks should not be less than 50 pieces.

[0056] Preferably, the test should be carried out under the conditions of an ambient temperature of 10±5°C, a relative humidity of 70±10%RH and standard atmospheric pressure, and the outer surface of the cement test block of the distribution line cement tower should be clean and free of dirt.

[0057] Furthermore, the breakdown test of cement test blocks of cement towers of distribution lines includes:

[0058] S11: Clamp the electrodes on the thickness layer of the cement test block of the cement tower of the distribution line, and slowly increase the voltage until the test block has internal penetration breakdown; Use the instrument to slowly increase the voltage until the cement test block of the cement tower of the distribution line has internal penetration breakdown;

[0059] S12: Record the voltage value when the test block is broken down in step S11;

[0060] S13: Repeat the above steps for multiple times to obtain a set of breakdown voltage value sequence data; perform S11 to S12 breakdown tests on each distribution line cement tower cement test block to obtain a set of breakdown voltage value sequence data

[0061] S14: Take the median of the breakdown voltage sequence data of the cement pole tower cement block of the distribution line obtained in S13 as the breakdown voltage value of the cement pole tower cement block of the distribution line at a probability of 50%.

[0062] Preferably, the test piece should be a specimen of not less than 1m in length cut from a distribution line cement tower, and the material, size, and spatial structure of the steel bars M1 inside the test piece should be consistent with those inside the actual distribution line cement tower.

[0063] Preferably, the material of the cement test block of the distribution line cement tower should be consistent with the material of the distribution line cement tower body. The breakdown test of the cement test block of the distribution line cement tower should be carried out under the conditions of ambient temperature 10±5℃, relative humidity 70±10%RH, and standard atmospheric pressure, and the outer surface of the cement test block of the distribution line cement tower should be clean and free of dirt.

[0064] Furthermore, the large current flow test of the steel bar M1 inside the cement tower of the distribution line includes:

[0065] S21: Ground one end of the steel bar M1 inside the cement tower of the distribution line, and apply a surge current with a 2.6 / 50μs lightning current waveform from the other end;

[0066] Make sure that the tail end of one of the steel bars M1 inside the cement tower of the distribution line is reliably grounded, and use an instrument to slowly increase the current from the head end of the internal steel bar M1 to perform a lightning current impulse test. The current waveform is the lightning current waveform, the parameter is selected as 2.6 / 50s, and the amplitude is adjustable.

[0067] S22: Starting from 0kA, the current is applied in increments of 1kA until the cement layer M2 inside the cement tower of the distribution line shows obvious thermal collapse damage;

[0068] S23: Record the current value causing thermal collapse in the above steps;

[0069] S24: Repeat the above steps multiple times to obtain a set of thermal breakdown current value sequence data;

[0070] Lightning current impulse tests S21 to S23 were carried out on the remaining steel bars inside the distribution line cement tower test piece, and at least 15 thermal collapse current values ​​were collected to obtain a set of thermal collapse current value series data.

[0071] S25: Take the median of the thermal breakdown current value sequence data as the thermal breakdown current value of the steel bar M1 inside the cement tower of the distribution line.

[0072] Preferably, a large current flow test is carried out on the internal steel bars M1 of the distribution line cement tower. The test piece should be a test piece with a length of not less than 1m cut from the distribution line cement tower as the test piece. The material, size and spatial structure of the internal steel bars M1 of the test piece should be consistent with the actual internal steel bars M1 of the distribution line cement tower.

[0073] Furthermore, according to the breakdown voltage characteristics and thermal collapse current characteristics, a direct lightning electrical simulation model of the distribution line cement tower is established. The direct lightning electrical simulation model includes a lightning current model, a wave impedance model, a tower volume resistance model, a tower internal inductance model and a tower natural grounding impulse grounding impedance model.

[0074] Furthermore, the amplitude of the lightning current model is taken as the lightning current amplitude with a probability of 90% within a circular range of 2km in diameter at the installation location of the cement tower of the distribution line, and the lightning current waveform parameter is 2.6 / 50μs.

[0075] Furthermore, the wave impedance model is taken as 150Ω, the tower volume resistance model is taken as 300MΩ, the tower internal inductance model is taken as 12μH, and the tower natural grounding impulse grounding impedance model is taken as 10Ω.

[0076] It should be noted that the test specimens with a length of not less than 1m were taken from the actual towers as the test pieces, which ensured a high degree of consistency between the test results and the actual situation. This method overcomes the errors that may be caused by using simulated samples in traditional methods.

[0077] In summary, the present invention obtains accurate breakdown voltage characteristics and thermal collapse current characteristics by conducting breakdown tests on cement test blocks and large current flow tests on internal steel bars M1, thereby ensuring the accuracy and reliability of lightning protection design, improving lightning protection effects, and reducing economic losses caused by lightning strikes; by establishing a comprehensive direct lightning electrical simulation model, including multiple key parameters such as lightning current, wave impedance, and tower volume resistance, the accuracy of the simulation is improved, the lightning protection design is closer to the actual situation, the design cost of the lightning protection device is reduced, and the safety performance of the distribution line is improved; by providing two complementary direct lightning damage protection devices and selecting and optimizing parameters based on the simulation results, the differentiated design of lightning protection measures is realized, and the applicability and effectiveness of the lightning protection device are improved.

[0078] Example 2

[0079] The second embodiment of the present invention provides a device for protecting a cement pole tower of a distribution line from direct lightning damage, which includes a breakdown voltage test of a cement test block of a cement pole tower of a distribution line.

[0080] The breakdown voltage test of cement test blocks of distribution line cement towers was carried out, and the breakdown voltage data of the test blocks were obtained, as shown in Table 1.

[0081] Table 1 Cement test block breakdown voltage test

[0082] Number of trials Breakdown voltage kV Number of trials Breakdown voltage kV 1 20.3 6 18.2 2 23.5 7 21.0 3 22.5 8 22.3 4 30.2 9 19.6 5 22.5 10 23.5

[0083] According to the data in Table 1, the median breakdown voltage of the test block is 22.5 kV, which is recorded as Uk.

[0084] A large current flow test was carried out on the steel bars M1 inside the cement tower of the distribution line, and the thermal breakdown current of the steel bars M1 inside the cement tower was found to be 263kAIm.

[0085] The experiment was conducted using a 2.6 / 50μs lightning current waveform. This particular waveform was chosen based on an in-depth study of actual lightning characteristics. The 2.6μs wave head time can accurately simulate the rapid rise characteristics of lightning, while the 50μs half-peak time matches the duration of typical lightning. In this embodiment, the thermal breakdown current of the steel bar M1 inside the cement tower we obtained was 263kA, which directly reflects the tolerance capacity of the actual tower.

[0086] A tower lightning strike model was built in the electromagnetic transient simulation software. The lightning current waveform parameter was selected as 2.6 / 50s, the wave impedance model value was 150Ω, the internal inductance model value was 12μH, and the tower natural grounding impulse grounding impedance model value was 10Ω.

[0087] First, the model is built according to the first unit 100, wherein the inductance of the grounding down conductor is 2μH, the grounding impedance parameter in the model is adjusted, and the voltage between the pole tower crossbar and the internal steel bar M1 in the model is observed. In this embodiment, when the grounding impedance parameter is adjusted to 0.1Ω, in the model, the voltage between the pole tower crossbar and the internal steel bar M1 is 30.2kA, which has exceeded the median breakdown voltage value of the test block of 22.5kV, which shows that the model is not applicable.

[0088] The model is constructed according to the second unit 200, the connection resistance between the tower crossbar and the internal steel bar M1 is set to 0.01Ω, the inductance of the model inductor element is adjusted, simulation is performed in the tower direct lightning model, and the current of the internal steel bar M1 entering the ground is observed. When the current of the internal steel bar M1 entering the ground in the model is less than the thermal collapse current of the internal steel bar M1 of the distribution line cement tower, the inductance value is used as the inductor element parameter value in the second unit 200.

[0089] In summary, for the distribution line tower, the tower lightning protection device is designed according to the second unit 200, and the parameters of the electrical components of the device are taken according to the data obtained in the previous steps.

[0090] Example 3

[0091] Reference Figure 2-4 , which is the third embodiment of the present invention, provides a device for protecting a cement tower of a distribution line from direct lightning damage, which includes a first unit 100 and a second unit 200.

[0092] Specifically, the first unit 100 is a tower crossbar separate grounding down conductor unit, including:

[0093] A first inductance element connected to the tower crosspiece 101, a grounding resistance element connected in series with the first inductance element, and a grounding down conductor 102 for connecting the grounding resistance element to the ground;

[0094] The second unit 200: a unit in which the tower crosspiece is connected to the internal steel bar M1 through an inductor element, comprising:

[0095] A second inductor element 201 connected to the tower crosspiece 101, used to connect the second inductor element 201 with the connection resistance of the internal steel bar M1;

[0096] The first unit 100 and the second unit 200 are selected according to the simulation results of the direct lightning electrical simulation model of the distribution line cement tower, which is established based on the breakdown voltage characteristics of the cement test block of the distribution line cement tower and the thermal collapse current characteristics of the internal steel bar M1.

[0097] Furthermore, the device for preventing direct lightning damage to cement towers of distribution lines includes:

[0098] A simulation model of the first unit 100 is established, wherein the inductance element is set to 2.0 μH and the grounding resistance element is an adjustable element;

[0099] In the direct lightning electrical simulation model, the grounding resistance element is adjusted to observe the voltage between the tower crossbar and the internal steel bar M1;

[0100] If the grounding resistance is greater than 0.2Ω and the voltage extreme value between the tower crosspiece and the internal steel bar M1 does not exceed the obtained breakdown voltage value, the first unit 100 is selected; otherwise, the second unit 200 is selected.

[0101] Furthermore, the device for preventing direct lightning damage to cement towers of distribution lines also includes:

[0102] A simulation model of the second unit 200 is established, wherein the connection resistance between the tower cross 101 and the internal steel bar M1 is 0.01Ω;

[0103] In the direct lightning electrical simulation model, the inductance of the inductor is increased to observe the current flowing into the ground by the internal steel bar M1.

[0104] When the ground current of the internal steel bar M1 is less than the obtained thermal breakdown current value, the inductance of the inductor element in this state is used as the value of the inductor element in the second unit 200.

[0105] Preferably, S41: the second unit 200 model is an electrical structure in which the inductor element is connected to the tower crosspiece, and the tower crosspiece is connected to the internal steel bar M1.

[0106] S42: Establish a direct lightning simulation model in S41, set the connection resistance between the tower crossbar and the internal steel bar M1 to 0.01Ω, increase the inductance of the inductor element in S41, perform simulation in the tower direct lightning model, and observe the current of the internal steel bar M1 entering the ground.

[0107] S43: If the internal steel bar M1 buried in the ground is less than the obtained thermal breakdown current of the internal steel bar M1 of the distribution line cement tower in the simulation step S42, the inductance of the inductor element in this state is used as the value of the inductor element in the second unit 200, and the other parameters remain unchanged.

[0108] Further, when the first unit 100 is selected:

[0109] The inductance value of the first inductor element is 2.0 μH, and the grounding resistance element is an adjustable resistor, and its resistance value is greater than 0.2Ω;

[0110] When the second unit 200 is selected:

[0111] The inductance value of the second inductor is determined through simulation, so that the ground current of the internal steel bar M1 is smaller than the thermal breakdown current value of the steel bar M1 inside the distribution line cement tower 103, and the resistance value of the connection resistor is 0.01Ω.

[0112] Preferably, S31: preferably the first unit 100 model, whose electrical model is composed of an inductor element and a grounding resistance element connected in series.

[0113] S32: The inductance element in the first unit 100 is set to 2.0 μH, and the grounding resistance element is an adjustable element. In the tower lightning model, the grounding resistance element in S31 is adjusted to reduce the grounding resistance value, and simulation is performed in the tower lightning model to observe the voltage between the tower crossbar and the internal steel bar M1.

[0114] S33: If the grounding resistance in the model is not less than 0.2Ω, and the voltage extreme value between the tower crossbar and the internal steel bar M1 in the simulation model does not exceed the breakdown voltage value of the distribution line cement tower cement test block with a probability of 50% obtained in step 3, the distribution line cement tower direct lightning damage protection device selects the first unit 100.

[0115] S34: If the grounding resistance in the model is below 0.2Ω, and the voltage between the tower crossbar and the internal steel bar M1 in the simulation model exceeds the breakdown voltage value of the distribution line cement tower cement test block with a probability of 50%, the separate grounding down conductor device of the tower crossbar is abandoned, and the second unit 200 is selected for simulation.

[0116] Importantly, it should be noted that the construction and arrangement of the present application shown in a number of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible, for example, the size, scale, structure, shape and proportion of various elements, and parameter values ​​such as temperature, pressure, etc., mounting arrangements, use of materials, color, directional changes, etc., without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of the execution function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0117] Furthermore, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment may not be described, i.e., those features that are not relevant to the best mode presently contemplated for carrying out the invention or those features that are not relevant to implementing the invention.

[0118] It should be understood that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but for those of ordinary skill having the benefit of this disclosure, the development effort will be a routine task of design, fabrication, and production without undue experimentation.

[0119] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preventing direct lightning damage to cement towers of power distribution lines, characterized in that: include, Conduct breakdown tests on cement test blocks of distribution line cement towers to obtain breakdown voltage characteristics of cement test blocks; Conduct a large current flow test on the internal steel bars of the distribution line cement tower to obtain the thermal collapse current characteristics of the internal steel bars (M1); Establishing a lightning electrical simulation model for distribution line cement towers according to the breakdown voltage characteristics and thermal collapse current characteristics; A direct lightning damage protection device for cement pole towers of distribution lines and its electrical parameters are selected based on the direct lightning electrical simulation model.

2. The method for protecting a cement tower of a power distribution line from direct lightning damage according to claim 1, characterized in that: The breakdown test of the cement test block of the distribution line cement tower comprises: Clamp the contact electrode on the thickness layer of the cement test block of the distribution line cement tower, and slowly increase the voltage until the test block has internal penetration breakdown; Record the voltage value when the test block breaks down; Repeat the above steps for several times to obtain a set of breakdown voltage value sequence data; The median of the breakdown voltage value sequence data is taken as the breakdown voltage value of the cement test block of the distribution line cement tower at a probability of 50%.

3. The method for protecting a cement tower of a power distribution line from direct lightning damage as claimed in claim 2, characterized in that: The large current flow test on the steel bars (M1) inside the cement tower of the distribution line includes: One end of the steel bar (M1) inside the cement tower of the distribution line is grounded, and a surge current with a 2.6 / 50μs lightning current waveform is applied from the other end; Starting from 0kA, the current is applied in increments of 1kA until the cement layer M2 inside the cement tower of the distribution line shows obvious thermal collapse damage; Record the current value that causes thermal collapse in the above steps; Repeat the above steps for several times to obtain a set of thermal collapse current value sequence data; The median of the thermal breakdown current value sequence data is taken as the thermal breakdown current value of the steel bars (M1) inside the cement tower of the distribution line.

4. The method for protecting a cement tower of a power distribution line from direct lightning damage as claimed in claim 3, characterized in that: The direct lightning electrical simulation model for the distribution line cement tower is established according to the breakdown voltage characteristics and the thermal collapse current characteristics. The direct lightning electrical simulation model includes a lightning current model, a wave impedance model, a tower volume resistance model, a tower internal inductance model and a tower natural grounding impulse grounding impedance model.

5. The method for protecting a distribution line cement tower from direct lightning damage as claimed in claim 4, characterized in that: The amplitude of the lightning current model is the lightning current amplitude with a probability of 90% within a circular range of 2km in diameter at the installation location of the cement tower of the distribution line, and the lightning current waveform parameter is 2.6 / 50μs.

6. The method for protecting a distribution line cement tower from direct lightning damage as claimed in claim 5, characterized in that: The wave impedance model is set to 150Ω, the tower volume resistance model is set to 300MΩ, the tower internal inductance model is set to 12μH, and the tower natural grounding impulse grounding impedance model is set to 10Ω.

7. A device for preventing direct lightning damage to cement towers of power distribution lines, characterized in that: The method for protecting cement towers of power distribution lines from direct lightning damage as claimed in claim 6; as well as, The first unit (100) is a tower crossbar independent grounding down conductor unit, comprising: A first inductance element connected to the tower crosspiece (101), a grounding resistance element connected in series with the first inductance element, and a grounding down conductor (102) used to connect the grounding resistance element to the ground; The second unit (200): a unit in which the tower crosspiece is connected to the internal steel bar (M1) via an inductor element, comprising: A second inductor element (201) connected to the tower crosspiece (101), used for connecting the second inductor element (201) with a connection resistor of the internal steel bar (M1); The first unit (100) and the second unit (200) are selected according to the simulation results of the direct lightning electrical simulation model of the distribution line cement tower, and the direct lightning electrical simulation model is established based on the breakdown voltage characteristics of the cement test block of the distribution line cement tower and the thermal collapse current characteristics of the internal steel bar (M1).

8. The device for protecting cement towers from direct lightning damage of power distribution lines as claimed in claim 7, characterized in that: The device for preventing direct lightning damage to cement towers of power distribution lines comprises: Establishing a simulation model of the first unit (100), wherein the inductance element is set to 2.0 μH and the grounding resistance element is an adjustable element; Adjusting the grounding resistance element in the direct lightning electrical simulation model and observing the voltage between the tower crosspiece and the internal steel bar (M1); If the grounding resistance is greater than 0.2Ω and the voltage extreme value between the tower crosspiece and the internal steel bar (M1) does not exceed the obtained breakdown voltage value, the first unit (100) is selected; otherwise, the second unit (200) is selected.

9. The device for protecting a cement tower from direct lightning damage of a power distribution line according to claim 8, characterized in that: The device for preventing direct lightning damage to cement towers of power distribution lines also includes: A simulation model of the second unit (200) is established, wherein the connection resistance between the tower crosspiece (101) and the internal steel bar (M1) is 0.01Ω; In the direct lightning electrical simulation model, the inductance of the inductor element is increased, and the current flowing through the internal steel bar (M1) into the ground is observed; When the ground current of the internal steel bar (M1) is less than the obtained thermal breakdown current value, the inductance of the inductor element in this state is used as the value of the inductor element in the second unit (200).

10. The device for protecting cement pole towers from direct lightning damage of power distribution lines according to claim 9, characterized in that: When the first unit (100) is selected: The inductance value of the first inductor element is 2.0 μH, and the grounding resistance element is an adjustable resistor, and its resistance value is greater than 0.2Ω; When the second unit (200) is selected: The inductance value of the second inductor element is determined through simulation, so that the ground current of the internal steel bar (M1) is smaller than the thermal breakdown current value of the internal steel bar (M1) of the distribution line cement tower (103), and the resistance value of the connection resistor is 0.01Ω.

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