A lightning protection method and device

Abstract

This invention discloses a lightning protection method that sets the connection between the lightning-attracting end and the grounding end to a high-impedance state under normal conditions and a conductive state under a high electric field. The invention also discloses a lightning protection device based on this method, comprising a lightning arrester, a down conductor, a grounding end, and a charge suppressor. The down conductor and charge suppressor are disposed between the lightning arrester and the grounding end of a wind turbine blade. The charge suppressor includes a high-electric-field conductive circuit and a positive charge repulsion circuit. The high-electric-field conductive circuit exhibits high impedance under normal conditions, and the positive charge repulsion circuit is a unilaterally conductive circuit under high electric field conditions. After unilateral conduction under high electric field conditions, the end of the positive charge repulsion circuit connected to the grounding end carries a positive charge. The advantages of this invention are: it solves the problem of active lightning attraction for facilities such as wind turbine blades, while ensuring that lightning strikes can be conducted to the ground, greatly reducing damage to facilities caused by lightning strikes.

Description

Technical Field

[0001] This invention relates to the field of lightning protection for wind power generation, and more particularly to a lightning protection method and lightning protection device. Background Technology

[0002] Lightning protection for wind turbine blades has always been a major challenge. Current technologies primarily rely on lightning protection and grounding, yet lightning disasters continue to occur frequently across various sectors. For example, lightning strikes on wind turbine blades are a common technical problem in the industry. Extensive data verification has shown that in scenarios like wind farms and wind turbine blades, lightning strikes are mainly caused by the upward leader generated by the facility itself (active lightning attraction). The damage caused annually is substantial; for instance, this has led to a year-on-year increase in the damage rate of wind turbine blades due to lightning. According to incomplete statistics from the World Wind Energy Association and the IEC, the annual blade damage rate due to lightning is as high as 7%. Current lightning protection methods largely rely on passive lightning attraction, neglecting active lightning attraction, making facilities like wind turbines extremely vulnerable to damage. Summary of the Invention

[0003] The technical problem to be solved by this invention is how to prevent wind turbine blades from actively attracting lightning without affecting lightning protection conduction. In response to the above-mentioned technical problem, a lightning protection method and device are proposed.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a lightning protection method, wherein the connection between the lightning conductor and the grounding terminal is configured to be in a high impedance state under normal conditions and to become a conductive state under a high electric field.

[0005] Another object of the present invention is to provide a lightning protection device, which includes a lightning arrester, a down conductor, a grounding terminal, and a charge suppressor. The lightning arrester is disposed at the end of the facility to be protected, and the grounding terminal is disposed at the end of the facility to be protected that is connected to the earth. The down conductor and the charge suppressor are disposed between the lightning arrester and the grounding terminal. The lightning arrester, the down conductor, the charge suppressor, and the grounding terminal are connected in sequence. The charge suppressor includes a high-field conducting circuit and a positive charge repulsion circuit. The high-field conducting circuit and the positive charge repulsion circuit are connected in parallel and then in series between the down conductor and the grounding terminal. The high-field conducting circuit is a circuit that conducts under high electric field conditions from the direction of the lightning arrester to the grounding terminal. The high-field conducting circuit normally exhibits high impedance. The positive charge repulsion circuit is a circuit that conducts on one side under high electric field conditions. After the positive charge repulsion circuit conducts on one side under high electric field conditions, the end connected to the grounding terminal carries a positive charge.

[0006] Furthermore, the positive charge repulsion circuit is a charge storage circuit.

[0007] Furthermore, the positive charge repulsion circuit includes a high-voltage capacitor.

[0008] Furthermore, the positive charge repulsion circuit also includes a first discharge tube, which is connected in series with a capacitor under high electric field, and one end of the first discharge tube is connected to a lead wire.

[0009] Furthermore, the high-electric-field conduction circuit includes a high-voltage varistor and a second discharge tube, which are connected in series. One end of the high-voltage varistor is connected to a lead wire, and one end of the second discharge tube is connected to a ground terminal. The circuit formed by the high-voltage varistor and the second discharge tube in series is connected in parallel with the circuit formed by the first discharge tube and the high-electric-field capacitor in series.

[0010] Furthermore, the second discharge tube is a gas-filled discharge tube.

[0011] Compared with the prior art, the beneficial effects of the present invention are:

[0012] This invention solves the problem of active lightning attraction for wind turbine blades by setting a charge suppressor between the lightning-attracting end and the grounding end. Under normal conditions (high electric field), the charge conduction channel between the blade down conductor and the grounding end is blocked. When the blade down conductor and the unit are in a high-resistance state or open circuit state under normal conditions, the down conductor and the unit are in a low-resistance conducting state after lightning strikes the blade lightning arrester. This solves the problem of active lightning attraction for wind turbine blade facilities, while ensuring that the lightning can be conducted to the ground when struck by lightning, which greatly reduces the damage to facilities caused by lightning. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0014] Figure 2 This is a circuit diagram of the charge suppressor in this invention. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] See Figures 1-2As shown in the illustration, this specific embodiment discloses a lightning protection method and device. Specifically, this embodiment uses a lightning protection system installed on a wind turbine blade as an example. The lightning protection system includes multiple parts such as a blade lightning arrester, down conductor, pitch bearing, hub, main bearing, frame, yaw bearing, and tower, which are electrically connected to form an overall lightning conduction channel. Because the wind turbine is reliably connected to the ground, it exhibits an overall positive charge characteristic. Simultaneously, due to the connection between the metal conductors and the metal blade lightning arrester within the wind turbine blades and the ground, under the influence of a high electric field, the blade lightning arrester continuously outputs positive charges from the ground. This causes the blade tip to easily release an upward leader towards the sky at 11-12 o'clock and 12-1 o'clock, facilitating conduction with the downward leader traveling through the thundercloud, forming a discharge channel, and leading to a lightning strike on the turbine. This specific embodiment of the invention uses a wind turbine as an example and does not represent a limitation on the scope of this application. It can also be applied to other fields with appropriate adaptive adjustments.

[0017] Specifically, the connection between the lightning arrester and the grounding terminal is configured to be in a high-impedance state under normal conditions and to become conductive under a high electric field. In this embodiment, the connection between the down conductor at the blade tip and the root is configured to be conductive under a high electric field, while other states prevent upward charge from flowing from the blade root.

[0018] It includes a lightning arrester 1, a down conductor 2, a grounding terminal 3, and a charge suppressor 4. The lightning arrester 1 is located at the end of the blade, and the grounding terminal 3 is located at the end of the blade that connects to the ground. Specifically, the grounding terminal 3 is the flange that fixes the blade. In the prior art, the lightning protection device structure of wind turbine generator sets is usually that the two ends of the down conductor 2 are directly connected to the lightning arrester 1 at the end of the blade and the blade flange at the root, so as to conduct electricity to the ground when struck by lightning.

[0019] Down conductor 2 and charge suppressor 4 are disposed between lightning arrester 1, grounding terminal 3, and blade flange. Lightning arrester 1, down conductor 2, charge suppressor 4, and grounding terminal 3 are connected sequentially. Charge suppressor 4 includes a high-field conducting circuit and a positive charge repulsion circuit. The high-field conducting circuit and the positive charge repulsion circuit are connected in parallel and then in series between down conductor 2 and grounding terminal 3. The high-field conducting circuit is a circuit that conducts under high electric field conditions from lightning arrester 1 to grounding terminal 3. The high-field conducting circuit normally exhibits high impedance. The positive charge repulsion circuit is a circuit that conducts on one side under high electric field conditions. After the positive charge repulsion circuit conducts on one side under high electric field conditions, the end connected to grounding terminal 3 carries a positive charge. Specifically, the positive charge repulsion circuit is a circuit structure that stores charge through a high-field capacitor. Specifically, the positive charge repulsion circuit includes a high-field capacitor 43.

[0020] In addition, the positive charge repulsion circuit also includes a first discharge tube 44, which is connected in series with a capacitor 43 under high electric field. One end of the first discharge tube 44 is connected to the downlead 2. Preferably, the second discharge tube 42 is a gas-filled discharge tube, and it can also be a discharge tube of this type, provided that the breakdown stability under high electric field of lightning is satisfied.

[0021] The high-electric-field conducting circuit includes a high-voltage varistor 41 and a second discharge tube 42, which are connected in series. One end of the high-voltage varistor 41 is connected to the downlead 2, and one end of the second discharge tube 42 is connected to the ground terminal 3. The circuit consisting of the high-voltage varistor 41 and the second discharge tube 42 connected in series is connected in parallel with the circuit consisting of the first discharge tube 44 and the high-electric-field capacitor 43 connected in series. When lightning breaks down the second discharge tube 42, the circuit charges the high-electric-field capacitor 43 for a short time. Since lightning involves the movement of electrons, when the first discharge tube 44 is broken down, negative electrons accumulate at the end of the high-electric-field capacitor 43 connected to the first discharge tube 44. After the lightning strike ends, the first discharge tube 44 returns to an open-circuit state, and the high-electric-field capacitor 43 stores negative charge. Correspondingly, the other end of the capacitor will exhibit a positive charge state, repelling the positive charge in the direction of the lower connecting blade flange, thereby further inhibiting the continued accumulation of positive charge. Meanwhile, the second discharge tube 42 is normally in an open circuit state, which prevents positive charges from rising and thus avoids the upward leader from causing a lightning strike.

[0022] To address the issue of rising leader (point discharge) problems caused by ground-based charge accumulation in wind turbine blade leads (including lightning arresters), the most effective technical approach is to block charge conduction through the blade down conductors. Since wind turbine blades are the highest rotating components of a wind turbine, they serve as lightning arresters for the entire system. When a blade is struck by lightning, it should be able to conduct the lightning current to the ground through a lightning conductor. This invention provides a transient blocking device that, under high electric field conditions, can block the charge supplied from the ground to the blade down conductors. After the blade lightning arrester receives the lightning strike, it can transfer the lightning energy through the down conductors to the hub or frame, and then through the tower to the ground. In the normal state (high electric field) of the lightning protection device of the present invention, the charge conduction channel between the blade down conductor and the unit (yaw bearing or nacelle, frame) is blocked, and a charge blocking system is installed at the blade root; when the blade down conductor and the unit are in a high resistance state or open circuit state under normal conditions, when lightning strikes the blade lightning arrester, the down conductor and the unit are in a low resistance conduction state.

[0023] Under normal high electric field conditions, the down conductor 2 and the grounding terminal 3 are in a high-resistance state or an open circuit state. This disconnection prevents the charge on the frame and hub from being conducted to the lightning arrester 1 through the down conductor 2, thus preventing the lightning arrester 1 from forming an upward leader and effectively reducing the lightning attraction effect on the blade. When a thundercloud discharge strikes the blade's lightning arrester 1, the surge voltage formed by the impedance between the lightning arrester 1 and the down conductor 2 reaches the breakdown voltage of the charge suppressor 4. At this point, the charge suppressor 4 enters a low-resistance conducting state, enabling the conduction of the lightning current.

[0024] This invention solves the problem of active lightning attraction for wind turbine blades by setting a charge suppressor between the lightning-attracting end and the grounding end. Under normal conditions (high electric field), the charge conduction channel between the blade down conductor and the grounding end is blocked. When the blade down conductor and the unit are in a high-resistance state or open circuit state under normal conditions, the down conductor and the unit are in a low-resistance conducting state after lightning strikes the blade lightning arrester. This solves the problem of active lightning attraction for wind turbine blade facilities, while ensuring that the lightning can be conducted to the ground when struck by lightning, which greatly reduces the damage to facilities caused by lightning.

[0025] In the description of this invention, it should be understood that the terms "coaxial," "bottom," "one end," "top," "middle," "other end," "upper," "side," "top," "inner," "front," "center," "both ends," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0026] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "screw connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A lightning protection device, characterized in that, The system includes a lightning arrester (1), a down conductor (2), a grounding terminal (3), and a charge suppressor (4). The lightning arrester (1) is located at the end of the facility to be protected. The grounding terminal (3) is located at the end of the facility to be protected that is connected to the earth. The down conductor (2) and the charge suppressor (4) are located between the lightning arrester (1) and the grounding terminal (3). The lightning arrester (1), the down conductor (2), the charge suppressor (4), and the grounding terminal (3) are connected in sequence. The charge suppressor (4) includes a high-field conducting circuit and a positive charge repulsion circuit. The high-field conducting circuit and the positive charge repulsion circuit are connected in parallel and then in series between the down conductor (2) and the grounding terminal (3). The high-field conducting circuit is a circuit that conducts under high electric field conditions from the direction of the lightning arrester (1) to the grounding terminal (3). The high-field conducting circuit normally exhibits high impedance. The positive charge repulsion circuit is a circuit that conducts on one side under high electric field conditions. The positive charge repulsion circuit exhibits high impedance under high electric field conditions. After being turned on on one side, one end connected to the ground terminal (3) carries a positive charge; the positive charge repulsion circuit is a charge storage circuit; the positive charge repulsion circuit includes a capacitor (43) under high electric field; the positive charge repulsion circuit also includes a first discharge tube (44), the first discharge tube (44) and the capacitor (43) under high electric field are connected in series, and one end of the first discharge tube (44) is connected to the down conductor (2); the high electric field conducting circuit includes a high-voltage varistor (41) and a second discharge tube (42), the high-voltage varistor (41) and the second discharge tube (42) are connected in series, one end of the high-voltage varistor (41) is connected to the down conductor (2), one end of the second discharge tube (42) is connected to the ground terminal (3), and the circuit after the high-voltage varistor (41) and the second discharge tube (42) are connected in parallel with the circuit after the first discharge tube (44) and the capacitor (43) under high electric field are connected in series; the second discharge tube (42) is a gas discharge tube.

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