WO2021223313A1 - Power transmission line without lightning shield line - Google Patents

Abstract

Provided is a power transmission line without a lightning shield line. The lightning and ice protection performance of a power transmission line is enhanced by removing a lightning shield line, which can easily be covered by ice, and by additionally installing a high-capacity lightning and ice-flashover protection combined insulator. The power transmission line without a lightning shield line comprises a lightning and ice protection insulator (100), a tower (200), wires (300) and a communication medium, wherein the through-current capability of the lightning and ice protection insulator (100) is higher than that of a traditional lightning arrester, and the lightning and ice protection insulator is used for suspending the wires (300) and can also conduct a lightning current to the tower (200); and the tower (200) is used for conducting the lightning current to the ground in a natural grounding manner. By means of the solution of the power transmission line without a lightning shield line, the problem of a traditional line whereby same is prone to the breakage of a lightning shield line due to same being covered by ice is solved; and the construction cost of a power transmission line is reduced, and the economy and reliability of the power transmission line are improved while the lightning and ice protection performance of the power transmission line is improved.

Description

Transmission line without lightning line

This disclosure claims the priority of a Chinese patent application filed with the Chinese Patent Office on May 8, 2020, the application number is 202010381892.X, and the invention title is "Transmission Line Without Lightning Line", the entire content of which is incorporated into this disclosure by reference .

Technical field

The present disclosure relates to the field of power transmission technology, and in particular to a power transmission line without a lightning line.

Background technique

With the rapid development of power construction, the power grid covers more and more areas, and transmission lines often need to be erected in some mountainous areas with complex terrain. These areas often have climate phenomena that are cold in winter and easy to be iced and thunder and lightning occur frequently in spring and summer. In the above-mentioned areas with special geographical environment, when encountering severe weather, the transmission line is prone to ice flashover or lightning flashover, which can cause tripping and blackout accidents, which seriously threatens the safe and stable operation of large power grids.

In the transmission line, the lightning protection wire is used to prevent the excessive lightning current from directly hitting the wire, which plays a role in lightning protection. However, the existing lightning protection wire of the transmission line still cannot effectively prevent the lightning protection. above 50. At the same time, because the lightning wire is located above the wire and there is no power frequency operating current, the ice coating of the lightning wire is more serious in winter, and it is very easy to cause the lightning wire to be disconnected or short-circuit accidents caused by the ice coating, causing the power system to trip and power outage. In the southern rain and snow disaster in 2008, taking Hunan Electric Power Company as an example, multiple transmission lines tripped due to ice coating and the distance between conductors and lightning conductors was less than their electrical insulation distance; 35 lightning conductors were disconnected on 500kV transmission lines, 220kV 83 lightning protection lines for transmission lines were broken, and 22 lightning protection lines for 110kV transmission lines were broken. After 2008, although there has not been a large-scale icing disaster, the accidents of icing and disconnection of lightning protection lines still occur frequently, which has caused a serious impact on the safe operation of the power grid.

In the prior art, the direct current ice melting method is usually used to melt the ice on the wire. However, because the lightning protection line is grounded by the poles and towers, the ice melting method is obviously different from that of the conventional wire. The ice melting technology is difficult and the ice melting cost is high. The cancellation of lightning protection lines can effectively improve the anti-icing capability of transmission lines. However, after the cancellation of the lightning protection line, the lightning protection performance of the transmission line is greatly reduced. Therefore, it is necessary to improve the lightning protection capability of transmission lines without lightning protection lines. In the existing lightning protection measures for transmission lines, in addition to traditional methods such as erecting coupled ground wires and reducing the grounding resistance of the tower, it is also possible to install line lightning arresters on the transmission line towers that are prone to lightning strikes to improve the lightning protection performance of the grid. . However, due to the parallel installation of lightning arresters and insulators, additional external hanging points need to be added to the tower. The construction volume is large, the economy is poor, and the insulation coordination is complicated. There have been many cases in China that the use of line arresters to prevent lightning flashover has been cancelled due to difficulties in installation and transformation. At the same time, the existing lightning arresters have insufficient current capacity and are easily damaged by direct lightning strikes and cannot be applied to transmission lines without lightning protection lines.

Based on this, there is an urgent need to propose technical solutions for lightning protection and ice protection for transmission lines without lightning protection lines to effectively solve the technical problems of lightning protection and ice protection for transmission lines in alpine mountainous areas.

Summary of the invention

(1) Technical problems to be solved

The technical problem to be solved by the present disclosure is to solve the problems of icing and disconnection of lightning protection lines and lightning strike faults in existing power transmission lines in alpine mountainous areas.

(2) Technical solution

In order to solve the above technical problems, the embodiments of the present disclosure provide a lightning-free power transmission line, including: lightning protection and ice protection insulators, towers, wires, and communication media. The lower end of the insulator is used to suspend the wires and the communication media. The upper end of the insulator is used to connect the tower; the insulator is used to connect the wire and the tower, the tower is used to support the weight of the wire and the communication medium, and at the same time lead the lightning current into the ground; the insulator includes a lightning protection section and an insulation section And a through-core rod; the through-core rod penetrates the lightning protection section and the insulation section, and is used to connect the tower and suspend the wire and the communication medium;

One end of the lightning protection section is connected in series with one end of the insulation section, the other end of the lightning protection section is suspended on a tower, and the other end of the insulation section is suspended with a wire;

The insulating section includes an insulating umbrella skirt and a pair of equalizing rings, the pair of equalizing rings are sleeved on the core rod and located at both ends of the insulating section, and are used to form a series gap of the lightning protection section; An insulating umbrella skirt is sleeved on the core rod to prevent external insulation flashover; the lightning protection section includes a zinc oxide resistor piece and a pair of fittings; the zinc oxide resistive piece is sleeved on the core rod, The pair of fittings are two bent metal electrodes located at both ends of the lightning protection section, one end of each of the metal electrodes is fixed on the through-core rod by crimping, and the other end is an electrode with a spherical structure , A parallel protection gap is formed between the two electrodes; the potential gradient of the zinc oxide resistor chip is not less than 300V/mm, and the 4/10μs flow capacity is not less than 300kA;

The distance between the two spherical electrodes constituting the parallel protection gap of the lightning protection section is determined by the following formula:

Among them, i(t) is the lightning current, u represents the overvoltage at both ends of the lightning protection section under the action of the lightning current, and A, B, and C are constants. The volt-ampere characteristic curve of the zinc oxide resistor can be obtained through testing and fitting; d Represents the distance between the parallel protection gaps of the lightning protection section; M and N are constants, and the lightning discharge voltage between the ball-ball electrodes of the pair of fittings at different distances d is obtained through testing and fitting; J represents the discharge voltage deviation , The value range of J is 0.9-1.1.

(3) Beneficial effects

Compared with the prior art, the above-mentioned technical solutions provided by the embodiments of the present disclosure have the following advantages:

The lightning protection and ice protection insulator in the embodiment of the present disclosure guarantees insulation and conducts lightning current to the tower at the same time. Its current flow capacity is higher than that of traditional lightning arresters, can withstand direct lightning strikes, and ensure that the lightning trip rate of transmission lines without lightning protection lines is less than the same A grounded transmission line of voltage level.

In the transmission line without lightning protection line provided by the embodiment of the present disclosure, the lightning protection line is removed from the transmission line and the lightning protection and ice protection insulator is added to the transmission line, the lightning protection and ice protection insulator parameter performance calculation model of the transmission line without lightning protection line is established, and the design is designed The tower structure without lightning line and the traditional OPGW communication alternative, break through the technical bottleneck of lightning protection and ice protection for transmission lines in high-cold mountainous areas, completely solve the problems of lightning protection line icing and disconnection and lightning failure, and improve the lightning protection and ice protection performance of transmission lines. Significantly reduce the cost of line construction, and enhance the reliability and economy of the power system.

It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure.

Description of the drawings

The drawings herein are incorporated into the specification and constitute a part of the specification, show embodiments consistent with the disclosure, and are used together with the specification to explain the principle of the disclosure.

In order to more clearly explain the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, In other words, other drawings can be obtained based on these drawings without creative labor.

Figure 1 is a schematic diagram of a transmission line in the prior art;

FIG. 2 is a schematic diagram of a power transmission line without a lightning line provided by an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of a lightning and ice protection insulator provided by an embodiment of the present disclosure;

4 is a schematic diagram of another lightning and ice insulator provided by an embodiment of the disclosure;

FIG. 5 is a schematic diagram of another lightning and ice insulator provided by an embodiment of the disclosure;

FIG. 6 is a schematic diagram of a traditional grounding structure of a pole and tower provided by an embodiment of the present disclosure;

FIG. 7 is a schematic diagram of a natural grounding structure of a pole and tower provided by an embodiment of the disclosure.

Detailed ways

In order to make the purpose, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present disclosure, not All examples. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present disclosure.

In related technologies, as shown in Figure 1, there are lightning protection lines in traditional transmission lines. The lightning protection line supports are provided to support the lightning protection lines. However, the installation of lightning protection lines cannot cope with the problem of icing and disconnection of the lightning protection lines in the high-cold area.

In order to solve the above technical problems, according to the embodiments of the present disclosure, a power transmission line without lightning protection line is provided, as shown in FIG. Not shown), in which: the lightning and ice insulator 100, the lower end of which is used to suspend the wire 300 and the communication medium, the upper end of which is used to connect the tower 200 to conduct lightning current to the tower 200; the tower 200 is used to support the wire 300 The weight of the insulator is 100, and the lightning current is introduced into the ground at the same time; the communication medium of the transmission line includes one of the following: all-dielectric self-supporting optical fiber cable ADSS or optical fiber composite phase line OPPC. In specific application scenarios, power communication is used to transmit power information such as power dispatch, relay protection, and equipment status. In the prior art, high-voltage lines mostly use OPGW communication optical cables as the communication medium. After the lightning protection wire is removed in this embodiment, the OPGW is replaced with ADSS or OPPC. The ADSS is installed under the power transmission wire, and the OPPC optical cable is installed in the wire to cancel lightning protection. Transmission line signal transmission behind the line.

In this embodiment, lightning protection and ice protection insulators are provided in the transmission line, and the lightning protection wire in the related technology is eliminated, so the corresponding environmental problems in the alpine region can be well dealt with. In specific applications, the wire is supported by lightning and ice insulators, the tower carries the weight of the wire, the lightning and ice insulators conduct the lightning current to the tower, and the tower leads the lightning current to the ground, which can effectively prevent lightning from affecting the transmission line. Damage.

Optionally, as shown in FIG. 3 in this embodiment, the lightning protection and ice protection insulator 100 includes a lightning protection section 10, an insulation section 20 and a core rod 30. The core rod 30 penetrates through the lightning protection section 10 and the insulating section 20, and the lower end of the core rod 30 is used to suspend the wire 300. The insulating section 20 includes a pair of equalizing rings 202 and an insulating umbrella skirt 204. The equalizing rings 202 are located at both ends of the insulating section 20 to form a series gap of the lightning protection section 10. A zinc oxide resistor 102 is installed in the lightning protection section 10 to absorb lightning current during lightning strikes.

Specifically, the lightning protection section 10 is connected in series with the insulating section 20, and the upper end of the lightning protection section 10 is suspended on a pole tower 200 for suspending the wire 300. A cylindrical core rod 30 penetrates through the lightning protection section 10 and the insulation section 20, and the core rod 30 is made of epoxy resin to ensure insulation and at the same time to withstand the tension of the wire.

When the lightning current acts on the wire 300, the two ends of the insulating section 20 are pierced by the arc, and the lightning current enters the earth along the zinc oxide resistor 102 inside the lightning protection section 10. After the lightning current decays, there is a gap between the zinc oxide resistor 102 and the insulating section 20. Cooperate with extinguishing the power frequency freewheeling arc to ensure the normal and stable operation of the line.

Optionally, in this embodiment, the lightning protection section 10 includes a zinc oxide resistive sheet 102 and a metal fitting 104, wherein the zinc oxide resistive sheet 102 is sleeved on the core rod 30; the metal fitting 104 is two bent metal electrodes One end of the electrode is fixed on the epoxy core rod 30 by crimping, and the other end has a spherical structure, and a protective gap is formed between the two spherical electrodes.

The ring resistor inside the lightning protection section can be a zinc oxide resistor chip with high potential gradient and high current flow capacity. Preferably, the potential gradient of the zinc oxide resistor chip is not less than 300V/mm, and the current flow capacity of 4/10μs is not less than 300kA. The height of the lightning and ice insulator structure can be set according to the actual window size, which can extinguish the power frequency freewheeling arc after the lightning current decays.

The hardware 104 at both ends of the lightning protection section 10 is connected in parallel to form a lightning protection gap. When the amplitude of the lightning current is too large, the residual voltage generated by the lightning current at both ends of the zinc oxide resistor 102 exceeds the breakdown voltage of the protection gap, and the lightning protection gap is Lightning breakdown, the lightning current flows into the tower and the ground through the lightning protection gap and the insulation section 20 to prevent excessive lightning current from causing damage to the zinc oxide resistor 102.

Optionally, in this embodiment, the insulating section 20 includes a pressure equalizing ring 202 and an insulating umbrella skirt 204, wherein the pressure equalizing ring 202 is located at both ends of the insulating section 20 and is used to form a series gap of the lightning protection section 10. In an actual application scenario, when a lightning strike occurs, the series gap of the lightning protection section 10 formed by the equalizing rings at both ends of the insulating section 20 is broken down, and the lightning current flows into the ground through the lightning protection section 10. A silicone rubber umbrella skirt 204 is wrapped on the outer surface of the lightning and ice insulator to prevent flashover of the external insulation.

One end of the lightning protection section 10 is connected with the insulating section 10, and the other end is suspended on the pole tower 200. By connecting the lightning protection section 10 and the insulation section 20 in series, the technical effect of the integration of the insulator and lightning arrester is realized, and the problems of icing of the lightning protection wire and the lightning protection installation of the lightning arrester are solved at the same time, and the economic efficiency is poor.

Further optionally, in another embodiment shown in FIG. 4, the lightning protection and ice protection insulator 100 includes a lightning protection section 10, an insulation section 20 and a core rod 30. The structure of the lightning protection section 10 is the same as that of the embodiment in FIG. 3, but the difference is that the insulating section 20 connected to the lightning protection section 10 includes two parallel sections. The structure of each of the two parallel sections is the same as that of the single The insulation section 20 is the same. The core rod 30 has an inverted Y shape and penetrates the two parallel parts of the lightning protection section 10 and the insulation section 20. The two lower ends of the core rod 30 of the inverted Y shape are used to suspend the wire 300. Preferably, the lower half of the inverted Y-shaped core rod 30 and the wire 300 form an isosceles triangle. Further, the insulating section 20 may include more than two parallel sections, and the structure of each parallel section is the same as the single insulating section 20 in FIG. 3.

Further optionally, in another embodiment shown in FIG. 5, the lightning protection and ice protection insulator 100 includes a lightning protection section 10, an insulation section 20 and a core rod 30. The structure of the insulating section 20 is the same as that of the embodiment in FIG. 3, but the difference is that the lightning protection section 10 connected by the insulating section 20 includes two parallel sections. Same for Thunder Section 10. The core rod 30 is Y-shaped and penetrates the two parallel parts of the lightning protection section 10 and the insulating section 20. The two upper ends of the Y-shaped core rod 30 are suspended on the pole tower 300. Preferably, the upper half of the Y-shaped core rod 30 and the horizontal part of the suspended pole tower 200 form an isosceles triangle. Further, the lightning protection section 10 may include more than two parallel sections, and the structure of each parallel section is the same as the single lightning protection section 10 in FIG. 3.

The lightning protection section of the lightning and ice protection insulator can be regarded as a lightning arrester in the traditional sense. In order to ensure that the lightning protection and ice protection insulator can effectively protect against lightning, it must have sufficient energy absorption capacity. The current flow capacity of the lightning protection section is determined by the line corridor. The characteristics of lightning activity, tower structure, grounding resistance and other parameters are jointly determined. Assuming that the lightning resistance level of the transmission line without lightning protection line is I ₀ , the current capacity of the lightning arrester in the lightning protection section is calculated by the following formula:

In the above formula, i(t) is the standard surge current capacity of the lightning protection section, and its wave head/wave tail time is 4/10μs respectively; u(t) represents the corresponding residual voltage of the lightning protection section under the action of large current; i ₀ (t) is the lightning current flowing through the lightning protection section, the waveform is taken as the standard lightning wave, its wave head/wave tail time is 2.6/50μs respectively, the amplitude is I ₀ *a, a is the lightning protection when the wire is struck by lightning The lightning current shunt coefficient of the segment; u ₀ (t) is the residual voltage at both ends of the lightning protection segment under the action of _{i 0 (t); T represents the lightning current action time.}

The electromagnetic transient simulation model of non-lightning line transmission line including lightning and ice protection insulators is established in the simulation software. In the simulation results, the relationship between the current capacity of the lightning protection and ice protection insulators and the lightning trip rate is calculated. In the simulation, the tower adopts Multiwave impedance model, the grounding resistance is 5 ohms. The lightning current adopts the standard lightning current waveform of 2.6/50μS. When lightning strikes directly below the lightning and ice insulator of the central tower, a single lightning and ice insulator bears the largest lightning current. In a specific application scenario, take the lightning strike density of 3.1 times/km ² .a in the thunderous area, and the lightning current amplitude probability P is shown in formula (2), where I is the lightning current amplitude:

The relationship between the current capacity of the lightning protection and ice protection insulator and the lightning trip rate is shown in Table 1. Considering the multiple lightning process, the corresponding current capacity of the lightning protection and ice protection insulator is selected according to the lightning protection requirements of different voltage levels in practical applications.

Table 1 Corresponding relationship between current capacity and lightning trip rate

Table 2 shows the correspondence relationship between transmission lines of different voltage levels and the current capacity of lightning and ice flashover composite insulators.

Table 2 Current capacity parameters of lightning and ice flashover composite insulators of different voltage levels

Voltage level	110kV	220kV	500kV	1000kV
4/10μs impulse flow	150-175kA	175-400kA	400-500kA	≥500kA
2ms square wave flow	1000-1500A	1500-2000A	2000-3000A	≥3000A

In the prior art, it is determined that a breakdown accident occurs when the lightning overvoltage exceeds the flashover voltage of the insulator. In this embodiment, it is determined that a trip occurs when the energy flowing through the lightning protection section exceeds the energy tolerance of the lightning protection and ice flashover composite insulator. Accident, that is, the corresponding relationship between the lightning trip rate of the transmission line and the current capacity is calculated based on the lightning distribution characteristics.

Optionally, in this embodiment, the lightning protection section of the lightning protection and ice protection insulator is connected in parallel with the protection gap, and the electrode distance is determined by the following formula:

In the above formula, i(t) is the lightning current, u represents the overvoltage at both ends of the lightning protection section under the action of the lightning current, and A, B, and C are constants. The volt-ampere characteristic curve of the zinc oxide resistor is obtained through the test and fitted Obtained; d represents the distance between the parallel protection gaps of the lightning protection section, M and N are constants. Through the test, the lightning discharge voltage between the 104 ball and the ball electrode of the fitting at different distances d is obtained and fitted; where J represents consideration For the deviation of the discharge voltage after humidity, rainfall and other factors, the value range of J is between 0.9-1.1.

Different from the prior art, this embodiment considers the influence of rainfall and humidity when calculating the breakdown voltage of the gap. For example, when the air humidity is 100%, the breakdown voltage is increased relative to 70%-80% humidity. 1.1 times (J takes 1.1); under rain conditions, the breakdown voltage is reduced to 0.9 times (J takes 0.9).

For transmission lines without lightning protection lines, when the grounding resistance is continuously increasing between 5Ω-3000Ω, as the grounding resistance increases, the lightning protection performance of the transmission line continues to improve. FIG. 6 is a schematic diagram of a traditional grounding structure of a pole and tower provided by an embodiment of the present disclosure; FIG. 7 is a schematic diagram of a natural grounding structure of a pole and tower provided by an embodiment of the disclosure. In Figures 6 and 7, the solid line represents the metal pole and the dashed line represents the ground plane, and the grounding body of the pole and tower is below the ground plane. Optionally, in this embodiment, the tower structure is improved, and the ground electrodes of the tower before and after the lightning line are eliminated. The comparison relationship is shown in FIG. 6 and FIG. 7. It can be seen from Figure 7 that the natural grounding method is adopted for the poles and towers after the ground wire is removed, without a separate grounding body structure, and no soil resistance reduction measures, which increases the lightning protection performance of the transmission line and reduces the construction cost of the transmission line.

Optionally, in this embodiment, the power transmission line is not provided with a lightning protection line. In specific application scenarios, for example, in the related technology, the lightning protection wire support is the weak point of the tower. For the tower in the transmission line without lightning protection wire in this embodiment, the corresponding lightning protection wire support can be cancelled to prevent repetition. The support of the lightning protection cable under ice broke.

Through the embodiments of the present disclosure, the lightning protection and ice protection scheme of the transmission line in which the lightning protection line is eliminated and the lightning protection and ice insulator is added to the transmission line, the parameter performance calculation model of the lightning protection and ice protection insulator for the transmission line without lightning protection line is established, and no lightning protection is designed The pole tower structure is an alternative method of communication with the traditional OPGW. Break through the technical bottleneck of lightning protection and ice protection for transmission lines in high-cold mountain areas, completely solve the problems of lightning protection line icing and disconnection and lightning strike faults, while improving the lightning protection and ice protection performance of transmission lines, greatly reducing line construction costs, and enhancing the reliability of the power system Sex and economy.

It should be noted that in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply these There is any such actual relationship or sequence between entities or operations. Moreover, the terms "include", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes those that are not explicitly listed Other elements of, or also include elements inherent to this process, method, article or equipment. If there are no more restrictions, the element defined by the sentence "including a..." does not exclude the existence of other identical elements in the process, method, article, or equipment that includes the element.

The above are only specific implementations of the present disclosure, so that those skilled in the art can understand or implement the present disclosure. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to the embodiments shown in this document, but should conform to the widest scope consistent with the principles and novel features disclosed in this document.

Industrial applicability

The present disclosure cancels lightning protection lines in the transmission lines and installs lightning and ice protection insulators, establishes a lightning protection and ice protection insulator parameter performance calculation model for transmission lines without lightning protection lines, and designs a tower structure without lightning protection lines and a traditional OPGW communication alternative. , Broke through the technical bottleneck of lightning protection and ice protection for transmission lines in high-cold mountain areas, completely solved the problems of lightning protection line icing and disconnection and lightning strike failure, and at the same time improved the lightning protection and ice protection performance of transmission lines, greatly reduced line construction costs, and enhanced power System reliability and economy have strong industrial applicability.

Claims (9)

1. A power transmission line without lightning protection wire, comprising a lightning and ice protection insulator (100), a tower (200), a wire (300) and a communication medium, and the lower end of the insulator (100) is used for suspending the wire (300) and the communication medium, The upper end of the insulator (100) is used to connect the tower (200); the insulator (100) is used to connect the wire (300) and the tower (200), and the tower (200) is used to support the wire (300) And the weight of the communication medium, and the lightning current is introduced into the ground at the same time, characterized in that: the insulator (100) includes a lightning protection section (10), an insulation section (20) and a core rod (30); the core The rod (30) penetrates the lightning protection section (10) and the insulating section (20), and is used for connecting the pole tower (200) and suspending the wire (300) and the communication medium;

   One end of the lightning protection section (10) is connected in series with one end of the insulation section (20), the other end of the lightning protection section (10) is suspended on a tower (200), and the other end of the insulation section (20) is suspended with a wire (300);

   The insulating section (20) includes an insulating umbrella skirt (204) and a pair of equalizing rings (202), and the pair of equalizing rings (202) are sleeved on the core rod (30) and located in the insulating section The two ends of (20) are used to form the series gap of lightning protection section; the insulating umbrella skirt (204) is sleeved on the core rod to prevent external insulation flashover; the lightning protection section (10) It includes a zinc oxide resistor piece (102) and a pair of fittings (104); the zinc oxide resistor piece (102) is sleeved on the core rod (30), and the pair of fittings (104) are located in the lightning protection Two bent metal electrodes at both ends of the section (10), one end of each metal electrode is fixed on the through-core rod (30) by crimping, and the other end is an electrode with a spherical structure. A parallel protection gap is formed between the electrodes; the potential gradient of the zinc oxide resistor is not less than 300V/mm, and the 4/10μs flow capacity is not less than 300kA;

   The distance between the two spherical electrodes constituting the parallel protection gap of the lightning protection section is determined by the following formula:

   

   Among them, i(t) is the lightning current, u represents the overvoltage at both ends of the lightning protection section under the action of the lightning current, and A, B, and C are constants. The volt-ampere characteristic curve of the zinc oxide resistor can be obtained through testing and fitting; d Represents the distance between the parallel protection gaps of the lightning protection section; M and N are constants, and the lightning discharge voltage between the ball-ball electrodes of the pair of fittings (104) at different distances d is obtained through testing and fitting; J represents Discharge voltage deviation, the value range of J is between 0.9-1.1.
2. The lightning-free power transmission line according to claim 1, wherein the insulating section (20) includes at least two sections connected in parallel, each of which includes an insulating umbrella skirt (204) and a pair of equalizing rings (202), the pair of pressure equalizing rings (202) are sleeved on the through core rod (30) and located at the two ends of each parallel part to form a lightning protection section series gap; the insulating umbrella skirt (204) Set on the core rod to prevent flashover of external insulation;

   The core rod (30) is inverted Y-shaped, and penetrates the two parallel parts of the lightning protection section (10) and the insulating section (20), the inverted Y-shaped core rod The two lower ends of (30) are used to hang the wires (300).
3. The lightning-free power transmission line according to claim 2, characterized in that the lower half of the inverted Y-shaped through core rod (30) and the wire (300) form an isosceles triangle.
4. The power transmission line without lightning protection line according to claim 1, characterized in that:

   The lightning protection section (10) includes at least two sections connected in parallel, each of which includes a zinc oxide resistor piece (102) and a pair of fittings (104); the zinc oxide resistor piece (102) is sleeved on the core On the core rod (30), the pair of fittings (104) are two bent metal electrodes located at both ends of the lightning protection section (10), and one end of each metal electrode is fixed to the On the core rod (30), the other end is an electrode with a spherical structure, and a parallel protection gap is formed between the two electrodes;

   The core rod (30) is Y-shaped, and penetrates the two parallel parts of the lightning protection section (10) and the insulating section (20), and the Y-shaped core rod (30) The two upper ends are suspended from the pole tower (200).
5. The lightning-free power transmission line according to claim 4, characterized in that the upper half of the Y-shaped through core rod (30) and the horizontal part of the suspended tower (200) form an isosceles triangle.
6. The power transmission line without lightning protection line according to claim 1, wherein the lightning protection flow capacity of the lightning protection section in the insulator is calculated by the following formula:

   

   Among them, i(t) is the standard surge current capacity of the lightning protection section, and its wave head/tail time is 4/10μs respectively; u(t) represents the corresponding residual voltage of the lightning protection section under the action of large current; i ₀ (t) is the standard lightning wave, the wave head/tail time is 2.6/50μs respectively, the amplitude is I ₀ *a, a is the lightning current shunt coefficient entering the lightning protection section when lightning strikes the wire, I ₀ is no lightning protection wire The lightning resistance level of the transmission line; u ₀ (t) is the residual voltage at both ends of the lightning protection section under the action of _{i 0 (t); T represents the lightning current action time;}

   The electromagnetic transient simulation model of non-lightning line transmission lines including lightning and ice protection insulators is established in the simulation software, and the relationship between the current capacity of the lightning protection and ice protection insulators and the lightning trip rate is calculated. According to the lightning protection of different voltage levels in actual applications Need to select the corresponding lightning and ice insulator flow capacity.
7. The power transmission line without lightning conductors according to claim 6, characterized in that, in the simulation software, the tower adopts a multi-wave impedance model, and the ground resistance is 5 ohms; the lightning current adopts the standard lightning current waveform of 2.6/50 μS; When the central tower is directly under the lightning and ice insulator, a single lightning and ice insulator bears the largest lightning current; in a specific application scenario, take the lightning strike density of 3.1 times/km ² ·a in the lightning area, and the lightning current amplitude probability P is shown in the following formula, where I is the lightning current amplitude:

   
8. The lightning-free power transmission line according to claim 1, wherein the communication medium includes at least one of an all-dielectric self-supporting optical cable ADSS or an optical fiber composite phase line OPPC, and the ADSS is installed under the power transmission line. The OPPC is installed in the power transmission line.
9. The power transmission line without lightning line according to claim 1, characterized in that the power transmission line without lightning line does not have overhead lightning line and lightning line support; the tower adopts natural grounding and does not require a separate grounding body structure.

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