Power transmission line lightning protection device with dual functions of energy consumption saving and lightning protection

Abstract

The invention relates to the technical field of lightning protection, and provides a power transmission line lightning protection device with dual functions of energy consumption saving and lightning protection, which comprises a pilot-operated rainwater capacitive switch element, an insulator string with a gap and an overhead lightning conductor, an overhead lightning conductor is connected with the iron tower body through the insulator string with the gap; and the pilot-operated rainwater capacitive switch element is connected with a grounding cross arm of the iron tower body after being in T-shaped connection with the overhead lightning conductor. According to the embodiment of the invention, the pilot-operated type rainwater capacitive switch element is installed below the insulator string with the gap to serve as a new bypass capacitive channel, and when it rains in thunderstorm days, ground charges can be conducted to the overhead lightning conductor from the iron tower body through a rope of the pilot-operated type rainwater capacitive switch element, so that the transmission of pilot charges is realized, and the ground charges are protected. Therefore, lightning strike can be preferentially hit to the lightning conductor, and induction shielding failure tripping accidents caused by the lightning strike to the phase conductor by bypassing the lightning conductor can be prevented.

Description

Technical Field

[0001] The present disclosure relates to the field of lightning protection technology, and more particularly, to a lightning protection device for transmission lines having dual functions of energy conservation and lightning strike protection. Background Art

[0002] In high-voltage transmission lines of 220 kV and above, there is an electromagnetic induction phenomenon between the overhead ground wire and the transmission conductors. Due to the spatial arrangement limitations of the conductors and the ground wire, the induced electromotive forces generated by each phase conductor on the overhead ground wire cannot cancel each other out, resulting in a longitudinal induced electromotive force in the overhead ground wire. Due to the existence of this induced electromotive force, the overhead ground wire will not only generate an induced current but also may cause power loss. Especially in large-scale and high-voltage transmission lines, the problem of power loss in the overhead ground wire gradually emerges.

[0003] Currently, transmission lines generally adopt the method of grounding tower by tower, forming a loop between the overhead ground wire and the grounding body. Although this approach effectively ensures safety, it also causes the problem of power loss. The traditional calculation method of power loss in transmission lines only considers the loss caused by the resistance of the conductors and ignores the induced power loss of the overhead ground wire. This makes the actual calculation of line loss have a large deviation. Especially for the power grid in East China, the annual power loss due to the overhead ground wire can reach about 1.5 billion kWh. Although the insulation transformation of the ground wire can effectively eliminate this loss, in a long transmission line, the insulated ground wire may cause an increase in the induced voltage, which in turn affects the lightning protection ability of the line. Summary of the Invention

[0004] At least one embodiment of the present disclosure provides a lightning protection device for transmission lines having dual functions of energy conservation and lightning strike protection. By installing a pilot rain capacitive switch element below the gap insulator string as a new bypass capacitive channel, when it rains during a thunderstorm, the ground charge can be conducted from the tower body to the overhead lightning protection wire through the rope of the pilot rain capacitive switch element, thereby realizing the transfer of pilot charge. Furthermore, it can achieve that lightning strikes the lightning protection wire first, preventing the induced shielding failure tripping accident caused by lightning bypassing the lightning protection wire and striking the phase conductor.

[0005] An embodiment of the present disclosure provides a lightning protection device for transmission lines having dual functions of energy conservation and lightning strike protection, including a pilot rain capacitive switch element (1), a gap insulator string (2), and an overhead lightning protection wire (3);

[0006] The overhead lightning protection wire (3) is connected to the tower body through the gap insulator string (2);

[0007] The pilot rain capacitive switch element (1) is T-connected to the overhead lightning protection wire (3) and then connected to the grounding cross arm of the tower body.

[0008] In some possible embodiments, the pilot rain capacitive switch element (1) includes a rainwater adaptive equivalent capacitor composed of double electrode plates, a rain collecting funnel and a water seepage hole; wherein, an asbestos rope is threaded between the double electrode plates of the rainwater adaptive equivalent capacitor.

[0009] In some possible embodiments, under the preset thunderstorm weather conditions, the pilot rain capacitive switch element (1) is in a conducting state.

[0010] In some possible embodiments, under the preset normal weather conditions, the pilot rain capacitive switch element (1) is in an off state.

[0011] In some possible embodiments, the gap insulator string (2) includes a ceramic insulator with discharge gap needles at both ends.

[0012] In some possible embodiments, the gap insulator string (2) further includes a composite insulator with discharge gap needles at both ends.

[0013] In some possible embodiments, the gap of the discharge gap needle is 4 - 5 cm.

[0014] In some possible embodiments, the overhead lightning protection wire (3) includes steel wires.

[0015] In some possible embodiments, the overhead lightning protection wire (3) further includes an optical fiber composite overhead ground wire.

[0016] In some possible embodiments, the overhead lightning protection wire (3) further includes an aluminum conductor steel reinforced.

[0017] The lightning protection device for a transmission line provided in the embodiments of the present disclosure, which has the dual functions of saving energy consumption and protecting against lightning strikes, includes a pilot rain capacitive switch element, a gap insulator string, and an overhead lightning protection wire; the overhead lightning protection wire is connected to the iron tower body through the gap insulator string; the pilot rain capacitive switch element is connected to the overhead lightning protection wire in a T shape and then connected to the grounding cross arm of the iron tower body.

[0018] In this embodiment, a pilot rain capacitive switch element is installed below the gap insulator string as a new bypass capacitive channel. When it rains during a thunderstorm, the ground charge can be conducted from the iron tower body to the overhead lightning protection wire through the rope of the pilot rain capacitive switch element, thereby realizing the transfer of the pilot charge, and further preventing the lightning strike from hitting the phase conductor by bypassing the lightning protection wire and causing an induced shielding failure trip accident.

[0019] To make the above objects, features and advantages of the present disclosure more obvious and understandable, the following specific embodiments are given, and in conjunction with the accompanying drawings, the detailed description is as follows. Brief Description of the Drawings

[0020] To more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required to be cited in the embodiments will be briefly introduced below. These drawings are incorporated into the specification and constitute a part of this specification. These drawings illustrate the embodiments that conform to the present disclosure and are used together with the specification to explain the technical solutions of the present disclosure. It should be understood that the following drawings only illustrate some embodiments of the present disclosure and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0021] Figure 1 Shows a schematic diagram of high-frequency coupling of lightning strikes on a lightning protection wire to a phase conductor provided by an embodiment of the present disclosure;

[0022] Figure 2 Shows a schematic diagram of a lightning protection device for a transmission line with dual functions of energy conservation and lightning protection provided by an embodiment of the present disclosure;

[0023] Figure 3 Shows a schematic diagram of a pilot rain capacitive switch element provided by an embodiment of the present disclosure;

[0024] Figure 4 Shows a schematic diagram of a rain collection funnel in a pilot rain capacitive switch element provided by an embodiment of the present disclosure. Detailed Description of the Embodiments

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only some of the embodiments of the present disclosure, rather than all of them. Usually, the components of the embodiments of the present disclosure described and illustrated in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the drawings is not intended to limit the scope of the present disclosure to be protected, but only represents the selected embodiments of the present disclosure. Based on the embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present disclosure.

[0026] It should be noted that: Similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0027] In this text, the term "and / or" merely describes an associated relationship, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Additionally, the term "at least one" in this text means any one of multiple or any combination of at least two of multiple. For example, including at least one of A, B, and C can represent including any one or more elements selected from the set composed of A, B, and C.

[0028] With the continuous growth of power demand and the continuous expansion of the power grid scale, as the backbone network for power transmission, the operating efficiency and security of 220 kV and above transmission lines are directly related to the stability and reliability of the entire power system. However, during the operation of transmission lines, the induction and loss problems of overhead ground wires are becoming increasingly prominent. Traditional transmission line designs mainly focus on the current transmission efficiency and security of conductors. For overhead ground wires, although they are an important part of lightning protection, their own power losses are often underestimated or ignored. This neglect not only leads to deviations in the calculation of transmission line losses but also affects the economic operation of the power grid and the achievement of energy conservation and emission reduction goals. Therefore, in-depth research and solution of the induction and loss problems of overhead ground wires in 220 kV and above transmission lines are of great significance for improving the operating efficiency of the power grid, reducing line losses, and ensuring the security of power supply.

[0029] It has been found through research that the overhead ground wires in related technologies generally adopt the tower-by-tower grounding method. When the conductor is energized, this method will form a longitudinal induced electromotive force on the ground wire due to electromagnetic induction, and then generate a continuous induced current, resulting in power loss. The traditional transmission line loss calculation method only considers the power loss of conductor resistance and ignores the loss on the overhead ground wire, making the line loss calculation result have a large deviation. Although there are theoretical calculation models that can estimate the induced voltage and energy loss of the ground wire, there are still many challenges in practical applications.

[0030] To solve this problem, the existing technology has proposed a transformation scheme for insulating the overhead ground wire, that is, changing the grounding method of the ground wire from grounding at each tower to insulating from the ground to cut off the current path and eliminate power loss. However, while this scheme brings energy-saving effects, it also causes new problems - the induced voltage on the insulated overhead ground wire increases, especially in long-distance transmission lines, this phenomenon is more significant, resulting in a significant decline in lightning protection ability. The weakening of lightning protection performance not only threatens the safe operation of transmission lines but may also cause accidents such as lightning trips, affecting the continuity and stability of power supply. Therefore, how to maintain or improve the lightning protection ability of overhead ground wires while ensuring energy conservation and loss reduction has become an urgent technical problem to be solved.

[0031] Here, in order to effectively ensure the safe and stable operation of transmission lines in complex lightning environments and reduce the incidence of tripping accidents caused by lightning strikes, with reference to Figure 1 As shown, it is assumed that when the lightning strike point hits the center of the span of the overhead lightning protection wire, due to the existence of an equivalent capacitance C0 between the lightning protection wire and phase conductor A, this capacitance will form a specific electrical path under the action of lightning. If no corresponding measures are taken, after a lightning strike at the center of the span of the overhead lightning protection wire, the high-frequency components of the lightning will penetrate to the phase A conductor through induction and coupling effects. The intrusion of this high-frequency electrical energy will cause the voltage on the phase conductor to rise sharply. Once it exceeds the withstand voltage of the phase conductor insulator, the phase conductor insulator will be broken down, and then a flashover tripping accident will occur, seriously threatening the power supply reliability of the power grid.

[0032] It can be understood that the equivalent capacitance between the phase conductor and the lightning protection wire and ground wire is an important electrical parameter, and its value is related to factors such as the layout of the line and the conductor spacing. The general empirical value is C D = 0.01374 μF / 1km. When the span is 400 m, according to the calculation principle of capacitance, the equivalent capacitance C0 under this span can be calculated as C0 = 0.4 × 0.01374 = 5.5 nF. If the frequency f of the lightning high-frequency component is 250 kHz, its equivalent capacitive reactance This means that under the action of the lightning high-frequency component, this equivalent capacitance will present a capacitive reactance of about 116 Ω, providing a path for the lightning energy to invade the phase conductor.

[0033] Here, in order to prevent lightning from entering the capacitive channel of the phase conductor and effectively block the intrusion of the lightning high-frequency component on the phase conductor, a low-impedance bypass channel needs to be constructed. When lightning strikes, most of the lightning energy will preferentially pass through this bypass channel and be introduced into the ground, thus avoiding damage to the phase conductor.

[0034] Based on the above research, in the embodiments of the present disclosure, a lightning protection device for transmission lines with dual functions of energy conservation and lightning protection is provided, including a pilot-type rain capacitive switch element, a gap insulator string, and an overhead lightning protection wire; the overhead lightning protection wire is connected to the iron tower body through the gap insulator string; the pilot-type rain capacitive switch element is T-shaped connected to the overhead lightning protection wire and then connected to the grounding cross arm of the iron tower body.

[0035] In this embodiment, by installing a pilot-type rain capacitive switch element under the gap insulator string as a new bypass capacitive channel, when it rains during a thunderstorm, the ground charge can be conducted from the iron tower body to the overhead lightning protection wire through the rope of the pilot-type rain capacitive switch element, thereby realizing the transfer of the pilot charge, and further realizing that the lightning strike preferentially hits the lightning protection wire and preventing the induced shielding failure tripping accident caused by the lightning bypassing the lightning protection wire and hitting the phase conductor.

[0036] The following will describe in detail a lightning protection device for a transmission line with dual functions of energy conservation and lightning strike protection in conjunction with the accompanying drawings.

[0037] See Figure 2 As shown, it is a schematic diagram of a lightning protection device for a transmission line with dual functions of energy conservation and lightning strike protection provided by an embodiment of the present disclosure. Taking the lightning protection device for a transmission line with dual functions of energy conservation and lightning strike protection shown in the figure as an example, the device includes a pilot-type rain capacitive switch element 1, a gap insulator string 2, and an overhead ground wire 3; the overhead ground wire 3 is connected to the iron tower body through the gap insulator string 2; the pilot-type rain capacitive switch element 1 is T-connected to the overhead ground wire 3 and then connected to the grounding cross arm of the iron tower body.

[0038] Specifically, when the transmission line is struck by lightning, the pilot-type rain capacitive switch element 1 can cut off the current or provide an effective path, enabling the lightning to be safely introduced into the ground, thereby avoiding damage to the equipment. In addition, this switch element is designed as a pilot type and has a low triggering energy, enabling it to quickly respond to environmental changes and ensure that the impact of lightning strikes on the transmission line is minimized.

[0039] Exemplarily, referring to Figure 3 As shown, it is a schematic diagram of a pilot-type rain capacitive switch element provided by the present disclosure. The element includes a rain self-adaptive equivalent capacitor composed of double electrode plates, a rain collecting funnel, and a water seepage hole. Here, an asbestos rope passes through the double electrode plates of the rain self-adaptive equivalent capacitor, which can quickly respond to environmental changes and provide a low-impedance channel when high-frequency current passes through, thereby effectively guiding the lightning current into the ground.

[0040] Specifically, the principle of the pilot-type rain capacitive switch element is that since the lightning current is a high-frequency current, when rainwater fills the capacitor plates through the rain collecting funnel (the specific structure can refer to Figure 4 As shown), and with the addition of the guiding rope (i.e., asbestos rope) in the middle, the switch can exhibit a low impedance under high-frequency current and a high impedance under power frequency, thereby ensuring its high efficiency during lightning strikes and remaining insulated under normal current, thus reducing the energy consumption loss of the equipment.

[0041] Here, the diameter of the rain collecting funnel can be set to 5 cm to 30 cm; the gap between the double electrode plates of the rain self-adaptive equivalent capacitor can be set to 4 to 5 cm; the asbestos rope can be made of asbestos material with a diameter of 2 to 3 cm thick.

[0042] Exemplarily, when filling the container with rainwater, its equivalent capacitance value can reach the level of C = 200 nF to 500 nF. Here, if the capacitance value at this time is too small according to the project standard, the distance d between the plates can be adjusted. When d is smaller, the capacitance C will increase. After adjusting to about C = 500 nF (under the condition of meeting the project standard), through installation and debugging, after connecting the pilot rain capacitive switch element to the ground wire, the capacitive reactance for the high-frequency current of the ground wire to flow into the ground can reach the target. In this way, the overhead ground wire can not only meet the requirements of energy conservation and loss reduction but also achieve the lightning protection requirements, ensuring the safe operation of the line.

[0043] In the embodiments of the present disclosure, after the rainwater fills the capacitor plates, the equivalent capacitance of the capacitor can reach 500 to 1500 nF, that is, it can approach a capacitance value of about 1 μF. In this way, the high-frequency current can easily pass through the pilot rain switch, and this switch is equivalent to an equivalent high-frequency path. However, at the power frequency of 50 Hz, it presents a high impedance, that is, it is in an insulated state at the power frequency. In this way, the purpose of both ensuring the reduction of losses of the ground wire and enabling the ground wire to play a lightning protection role is achieved.

[0044] Specifically, in the preset thunderstorm weather conditions, the pilot rain capacitive switch element 1 is in a conducting state under the lightning high-frequency current. In the preset normal weather conditions, the pilot rain capacitive switch element 1 is in an open state under the normal power frequency (such as 50 Hz).

[0045] It can be understood that the gap insulator string 2, as a support structure, plays the roles of isolation and support, can effectively prevent the current from being conducted through the iron tower, plays an electrical isolation role, and avoids lightning from being conducted to other system devices through the iron tower. At the same time, when the lightning strike voltage is too high, if the pilot rain capacitive switch element fails, the gap insulator string 2 can also serve as a backup protection for lightning strikes. Among them, the gap design of the gap insulator string 2 can enable this component to effectively block lightning strikes in thunderstorm weather, ensuring the safety of the system. In addition, the gap design also effectively reduces the maintenance cost of the equipment because the durability and reliability of the insulator are relatively high, reducing the common maintenance problems in traditional equipment.

[0046] In some possible embodiments, the gap insulator string 2 can be a ceramic insulator or a composite insulator with discharge gap needles at both ends, and the gap of the discharge gap needles of the two can be set to 4 to 5 cm.

[0047] In some possible embodiments, its discharge voltage can be designed to be at the level of 40 to 50 kV to meet the requirement of reducing the induced current of the ground wire to a basically zero level.

[0048] It is understandable that the overhead lightning protection wire 3 plays a role of basic support and lightning conduction in the whole device. It is connected to the iron tower body through the gap insulator string 2. Under normal operating conditions, the gap of the gap insulator string 2 maintains the insulation performance, keeping the overhead lightning protection wire 3 electrically isolated from the iron tower body. When lightning overvoltage occurs, the gap can be broken down to form a discharge channel, allowing the lightning current to pass through smoothly and be introduced into the iron tower body, and then flow into the ground.

[0049] In some possible embodiments, in order to select appropriate materials according to different application scenarios and requirements, taking into account factors such as cost, strength, corrosion resistance, and special functions (such as communication transmission) while ensuring the lightning protection effect, the overhead lightning protection wire 3 can use steel wire, optical fiber composite overhead ground wire, or aluminum conductor steel reinforced. The steel wire has high mechanical strength and electrical conductivity, and relatively low cost, and is suitable for lightning protection of general power lines. The optical fiber composite overhead ground wire (OPGW) can not only play a role in lightning protection but also transmit optical signals simultaneously to achieve communication functions, and is commonly used in transmission lines that require communication functions. The aluminum conductor steel reinforced combines the mechanical strength of steel and the electrical conductivity of aluminum, and can undertake certain power transmission tasks while meeting the lightning protection requirements, and is applied in some special lines.

[0050] Furthermore, the pilot rain capacitive switch element 1 is connected to the overhead lightning protection wire 3 in a T-shaped connection manner and then connected to the grounding cross arm of the iron tower body. Under normal weather conditions, due to the lack of sufficient moisture to form a conductive channel, the element presents a high impedance state and has no interference with the normal operation of the power transmission line. When there are frequent lightning activities or the environmental humidity is relatively high, rainwater accumulates on the surface of the element to form a conductive layer. At this time, the equivalent capacitance of the element increases and the capacitive reactance decreases, and the switch element is triggered to conduct, and the lightning energy is shunted to the ground in advance through it, reducing the lightning impact borne by the overhead lightning protection wire 3.

[0051] Here, the T-shaped connection manner is mainly because it can achieve a more stable and reliable electrical connection between the element and the overhead lightning protection wire 3. In the T-shaped connection structure, an electrical path similar to a "T" shape is formed between the element and the lightning protection wire. This structure can not only effectively disperse the current, reduce the risk of local overheating and arc generation, but also enhance the mechanical strength of the connection, ensuring that the connection between the element and the lightning protection wire will not be loosened or broken due to external forces under harsh weather conditions such as strong wind and heavy rain. In addition, the T-shaped connection manner helps to optimize the distribution of the electromagnetic field, reduce the influence of electromagnetic interference on the power transmission line, and improve the stability and safety of the entire power system.

[0052] In the embodiments of the present disclosure, a lightning protection device for a transmission line with the dual functions of energy consumption saving and lightning strike protection is provided. By installing a pilot rain capacitive switch element below the gap insulator string as a new bypass capacitive channel, when it rains during a thunderstorm, the ground charge can be conducted from the tower body to the overhead lightning protection line through the rope of the pilot rain capacitive switch element, thereby realizing the transfer of the pilot charge. Furthermore, it can be ensured that the lightning strike preferentially hits the lightning protection line and prevent the induced bypass strike tripping accident caused by the lightning bypassing the lightning protection line and hitting the phase conductor.

[0053] Those skilled in the art can understand that in the above method of the specific implementation manner, the writing order of each step does not mean a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined according to its function and possible internal logic.

[0054] Finally, it should be noted that the above-described embodiments are only specific implementation manners of the present disclosure, used to illustrate the technical solutions of the present disclosure, rather than limiting them. The protection scope of the present disclosure is not limited thereto. Although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: any person skilled in the art within the technical scope disclosed by the present disclosure can still modify the technical solutions recorded in the foregoing embodiments or easily think of changes, or perform equivalent replacements on some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure, and should all be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A lightning protection device for a transmission line with the dual functions of energy consumption saving and lightning strike protection, characterized in that, It includes a pilot-operated rain capacitive switch element (1), a gap insulator string (2), and an overhead lightning protection wire (3); The overhead lightning protection wire (3) is connected to the iron tower body through the gap insulator string (2); The pilot-operated rain capacitive switch element (1) is T-connected to the overhead lightning protection wire (3) and then connected to the grounding cross arm of the iron tower body.

2. The device according to claim 1, wherein, The pilot-operated rain capacitive switch element (1) includes a rain self-adaptive equivalent capacitor composed of double electrode plates, a rain collecting funnel, and a water seepage hole; wherein, an asbestos rope is threaded between the double electrode plates of the rain self-adaptive equivalent capacitor.

3. The device according to claim 2, wherein, In a preset thunderstorm weather condition, the pilot-operated rain capacitive switch element (1) is in a conducting state.

4. The device according to claim 2, wherein, In a preset normal weather condition, the pilot-operated rain capacitive switch element (1) is in an open state.

5. The device according to claim 1, characterized in that, The gap insulator string (2) includes ceramic insulators with discharge gap needles at both ends.

6. The device according to claim 1, characterized in that, The gap insulator string (2) further includes composite insulators with discharge gap needles at both ends.

7. The device according to any one of claims 5 or 6, characterized in that, The gap of the discharge gap needle is 4 - 5 cm.

8. The device according to claim 1, characterized in that, The overhead lightning protection wire (3) includes steel wires.

9. The device according to claim 1, wherein The overhead lightning protection wire (3) further includes an optical fiber composite overhead ground wire.

10. The device according to claim 1, characterized in that, The overhead lightning protection wire (3) further includes an aluminum conductor steel-reinforced wire.

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