Lightning protection mechanism and method for a wind blade

Abstract

This invention belongs to the field of wind power equipment technology, specifically a lightning protection mechanism and method for wind turbine blades. It includes a lightning arrester installed on the blade and a lower guide wire installed inside the blade, the lightning arrester and the lower guide wire being electrically connected. It also includes a conductive component installed on the outer surface of the blade, which guides the lightning current to the lightning arrester. This invention utilizes a sheet-like, multiple-layer design for the extended metal mesh, with the multiple extended metal meshes not directly connected. Therefore, during a lightning strike, the number of extended metal meshes through which the lightning current flows is reduced. When a local extended metal mesh is damaged, it can be directly replaced. Furthermore, the distribution of the extended metal mesh, lightning guide strips, and metal plates on the blade allows them to form a unified whole for overall blade protection while remaining separate, enhancing the guidance effect of the lightning current and reducing damage to the lightning protection mechanism.

Description

Technical Field

[0001] This invention belongs to the field of wind power equipment technology, specifically a lightning protection mechanism and method for wind turbine blades. Background Technology

[0002] Most wind farms are built in mountainous or hilly areas with rugged terrain and complex topography and climate, resulting in frequent lightning activity. Especially after entering summer, the blades, as the most exposed components of wind turbines, bear about 15%-20% of the probability of being struck by lightning. Severe lightning strikes can even destroy multiple lightning arresters, causing huge economic losses to wind farms due to the high cost of repairs and the long downtime. Therefore, lightning protection measures for the blades are very important.

[0003] In the lightning protection measures for blades, lightning protection systems are usually used to guide and avoid lightning. By installing lightning rods at the tips of the blades and using down conductors to guide the lightning guided in the lightning rods to the wind turbine hub, the lightning is discharged to the ground in conjunction with the grounding facilities of the wind turbine. However, since the protection range of the lightning rods located at the blade tips is limited, especially with the gradual increase in blade length, relying solely on the lightning rods at the blade tips to protect the blades is no longer sufficient for lightning protection.

[0004] In related technologies, to enhance the lightning protection range of wind turbine blades, a combination of lightning arresters and metal conductors is often used. For example, the article "Lightning Damage and Lightning Protection of Wind Turbine Blades" mentions using a full-coverage steel wire mesh as a lightning arrester to guide lightning. Another example is the lightning protection device for wind turbine blades published in Chinese Patent Application No. 2022108555991, which proposes using a detachable and replaceable conductive shell to cover the blade, thereby improving the guidance of lightning and reducing the probability of the blade being struck and damaged by lightning. While these methods can enhance the protection of the blades, the metal mesh, although convenient to install, has limitations in guiding lightning. After a lightning strike, the metal mesh is highly susceptible to damage due to the thermal effect and electromagnetic force of the lightning current. Therefore, it needs to be repaired and replaced after a lightning strike. However, because the metal mesh is integrally formed, it needs to be replaced as a whole after damage, making the maintenance work cumbersome and wasting metal mesh materials. While using a conductive shell to protect the blades can extend its service life under lightning strikes due to its high durability, the weight and volume of the conductive shell itself can negatively impact the aerodynamics of the blades. Therefore, this invention proposes a lightning protection mechanism and method for wind turbine blades to solve the above-mentioned technical problems. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies and solve the aforementioned technical problems, this invention proposes a lightning protection mechanism and method for wind turbine blades.

[0006] The technical solution adopted by the present invention to solve its technical problem is: a lightning protection mechanism for wind turbine blades according to the present invention includes a lightning arrester installed on the blade and a lower guide wire installed inside the blade. The lightning arrester and the lower guide wire are connected in a conductive manner. The lightning arrester, together with the lower guide wire, guides the lightning current to the root of the blade.

[0007] It also includes a conductive component mounted on the outer surface of the blade, which is used to guide the lightning current to the lightning arrester;

[0008] The conductive component includes at least two metal plates, which are respectively fixedly installed on the leading edge and trailing edge of the blade, and the metal plates are fixedly connected to the lightning arrester.

[0009] A lightning conductor strip, wherein the lightning conductor strip is a segmented conductor strip, the lightning conductor strip is fixedly attached to the suction surface of the blade, and the lightning conductor strip is located between two metal plates.

[0010] Preferably, the lightning guide strips are evenly distributed at equal intervals on the suction surface of the blade, and the length direction of the lightning guide strips is perpendicular to the length direction of the metal plate.

[0011] Preferably, an extended metal mesh is installed on both sides of the metal plate, the extended metal mesh is electrically connected to the metal plate, and the extended metal mesh extends to the suction surface and pressure surface of the blade.

[0012] Preferably, the extended metal mesh is a sheet-like structure, and the extended metal mesh is designed in multiples, with multiple extended metal meshes evenly arranged along the length direction of the metal plate, and the extended metal mesh and the metal plate are arranged in a fish skeleton shape.

[0013] Preferably, the extended metal mesh and the lightning conductor strips are arranged at intervals.

[0014] Preferably, the metal plate is fixedly mounted with uniformly distributed pressure plates on the side near the extended metal mesh. The pressure plates are arranged along the thickness direction of the metal plate, and an installation groove is formed between two adjacent pressure plates. The ends of the extended metal mesh are multi-layered and the multi-layered extended metal mesh extends into the installation groove.

[0015] Preferably, the blade has a mounting hole, the pressure plate has a through hole, and a fastening bolt is installed on the pressure plate. The fastening bolt is threadedly connected to the mounting hole through the through hole.

[0016] Preferably, conductive paste is filled between the mounting groove and the extended metal mesh to reduce the contact resistance between the extended metal mesh and the pressure plate.

[0017] A lightning protection method for wind turbine blades, comprising the following steps:

[0018] S1. Install lightning protection system: When modifying the blade for lightning protection, install multiple lightning rods at intervals at the tip and middle of the blade, and connect the lightning rods to the lower guide wire inside the blade.

[0019] S2. Install the metal plate: Bend the metal plate so that it fits against the leading and trailing edges of the blade, and use mechanical connection methods such as bolts to fix the metal plate to the metal surface of the lightning arrester.

[0020] S3. Install the extension metal mesh: The staff manually pry open the pressure plate, fold the end of the extension metal mesh and insert it into the installation groove between the pressure plates. After applying conductive paste, use fastening bolts to press the pressure plate and the extension metal mesh between the pressure plates, and then stick the rest of the extension metal mesh to the blade surface.

[0021] S4. Attaching the lightning conductor strip: Attach the lightning conductor strip to the gaps in the extended metal mesh, ensuring that both ends of the lightning conductor strip extend towards the metal plate.

[0022] S5. Lightning protection: When the intensity of the atmospheric electric field around the blade changes, the lightning protection mechanism on the blade forms multiple upward leaders. When the downward leader formed by the thundercloud connects with the upward leader on the blade, a lightning interception channel is formed. Under the guidance of the lightning conductor strip, the extended metal mesh and the metal plate, the lightning current is discharged to the ground through the lightning arrester and the lower guide wire, thereby preventing lightning from directly striking the blade.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. The lightning protection mechanism and method for wind turbine blades described in this invention, by setting up conductive components in conjunction with lightning arresters, increases the lightning interception range and enhances the protection effect on the blades. In specific implementation, a small-volume, easy-to-install lightning conductor strip is used to form an ionization channel, guiding the lightning current to flow onto a metal plate. The metal plates, arranged along the blade length, act as conductors for the lightning current, guiding it to flow into the lightning arrester and the lower guide wire, thereby reducing the damage caused by lightning to the blades. Simultaneously, when the lightning conductor strip is set up in conjunction with the metal plate, on the one hand, the lightning conductor strip increases the range and area of ​​lightning current interception, facilitating lightning arrest on the metal plate and enhancing the guiding effect on the lightning current. On the other hand, since the lightning conductor strip is distributed between adjacent metal plates, the guiding distance of the lightning conductor strip is shorter, reducing the probability of the lightning conductor strip failing to guide the lightning current, thereby increasing the lightning arrestion success rate of the conductive components and the lightning arrester.

[0025] 2. The lightning protection mechanism and method for wind turbine blades described in this invention, by designing the extended metal mesh in sheet form and in multiples, and by ensuring that the multiple extended metal meshes are not directly connected, reduces the number of extended metal meshes through which the lightning current flows during a lightning strike. When a local extended metal mesh is damaged, it can be directly replaced. Furthermore, the distribution of the extended metal mesh, lightning conductor strips, and metal plates on the blade allows them to form a whole for overall blade protection while remaining separate to enhance the guidance effect on the lightning current and reduce the damage of the lightning current to the lightning protection mechanism. Attached Figure Description

[0026] The invention will now be further described with reference to the accompanying drawings.

[0027] Figure 1 This is a perspective view of the present invention;

[0028] Figure 2 This is a schematic diagram showing the connections of the various components of the lightning protection mechanism of the present invention;

[0029] Figure 3 This is a structural diagram of the metal plate and the extended metal mesh of the present invention;

[0030] Figure 4 This is a partial schematic diagram of the present invention;

[0031] Figure 5 This is a cross-sectional view of the metal plate and pressing sheet of the present invention;

[0032] Figure 6 This is a flowchart of the method of the present invention;

[0033] In the diagram: 1. Lightning arrester; 11. Lower guide wire; 2. Metal plate; 21. Lightning conductor strip; 22. Extended metal mesh; 23. Pressure plate; 24. Mounting groove; 25. Mounting hole; 26. Through hole; 27. Fastening bolt. Detailed Implementation

[0034] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0035] like Figures 1 to 6 As shown, the lightning protection mechanism for a wind turbine blade according to the present invention includes a lightning arrester 1 installed on the blade and a lower guide wire 11 installed inside the blade. The lightning arrester 1 and the lower guide wire 11 are connected in a conductive manner, and the lightning arrester 1 cooperates with the lower guide wire 11 to guide the lightning current to the root of the blade.

[0036] It also includes a conductive component mounted on the outer surface of the blade, the conductive component being used to guide the lightning strike current to the lightning arrester 1;

[0037] The conductive component includes at least two metal plates 2, which are respectively fixedly installed on the leading edge and trailing edge of the blade, and the metal plates 2 are fixedly connected to the lightning arrester 1.

[0038] Lightning guide strip 21, wherein the lightning guide strip 21 is a segmented guide strip, the lightning guide strip 21 is fixedly pasted on the suction surface of the blade, and the lightning guide strip 21 is located between two metal plates 2;

[0039] When wind turbine blades are in normal use, because they are made entirely of materials such as fiberglass and are non-metallic, the surface of the blades has relatively little static charge on sunny days. However, in cloudy or rainy weather, the atmospheric electric field strength is constantly changing. Under the influence of a high electric field, a large number of induced positive charges are generated on the lower guide wire 11 inside the blade. Under the effect of electrostatic equilibrium, the bottom layer inside the blade carries an equal amount of negative charge, causing an upward leader to form on the blade surface and blade tip. The presence of the upward leader makes the blade capable of receiving lightning strikes. In practical applications, by setting up a lightning protection mechanism, the upward leader formed on the blade is linked with the lightning protection mechanism, causing the lightning strike channel to connect with the lightning protection mechanism, thereby utilizing the lightning protection mechanism to receive lightning strikes. Specifically, the blade tip... The lightning arrester 1 installed on the blade and the conductive components installed on the outer surface of the blade form an upward leader at the blade tip and the blade body. When the downward leader of the thundercloud connects with the upward leader on the blade, the lightning path will preferentially select the conductive components or lightning arrester 1 to guide the lightning current, causing the lightning current to be discharged into the ground along the lower guide wire 11. Specifically, when the blade is lightning-affected, due to the high position of the blade tip and the reduced thickness of the blade tip, the distance between the lower guide wire 11 located inside the blade and the outside is short, resulting in a small breakdown voltage between the lower guide wire 11 and the blade on the contact side. Therefore, most blade lightning occurs at the blade tip. Thus, the lightning arrester 1 and the lower guide wire 11 arranged at the blade tip can effectively protect the blade from most lightning strikes. The blades are continuously rotating, and due to the presence of water film, salt, and dirt on their surfaces, they also have the potential to be struck by lightning. Therefore, there is a certain probability that lightning strikes will occur on the blade body. Furthermore, the suction surface of the blade is more likely to attract dirt, making it more susceptible to lightning strikes than the pressure surface. Additionally, the thinner trailing edge of the blade is more likely to be struck than the leading edge. When the lightning current bypasses the blade tip and connects with the upward leader in the middle of the blade, the conductive components guide the lightning current. The conductive components on the outer surface of the blade primarily rely on metal plates 2 and lightning conductor strips 21 to guide the current. Metal plates 2 are fixedly installed on the leading and trailing edges of the blade and distributed along the entire length of the blade. The metal plate 2 is installed upwards and connected to the lightning arrester 1, primarily to guide the lightning current into the lightning arrester 1. To reduce the impact of the weight and shape of the metal plate 2 on the aerodynamics of the blade, the metal plate 2 is only installed at the leading and trailing edges of the blade. Simultaneously, lightning conductor strips 21, arranged on the suction surface of the blade, guide the lightning current laterally, causing it to flow onto the metal plate 2. The lightning conductor strips 21 are made of a series of metal sheets and resistive materials alternately arranged on a composite base. Under normal circumstances, due to the gaps between the metal sheets, the conductive path is open, and the entire lightning conductor strip 21 is an insulator. When struck by lightning, a large amount of charge begins to accumulate at the ends of adjacent metal plate segments 2, generating a feather-like electric arc. When the voltage reaches a certain value...A thin metal fragment will puncture the air above, forming an ionization channel through which lightning current can flow. By installing lightning conductor strips 21 between the metal plates 2, the suction surface between the metal plates 2 is protected. When a lightning strike occurs on the suction surface, the lightning conductor strips 21 guide the lightning current towards the metal plates 2 and then into the lightning arrester 1, thereby preventing damage to the blades from the lightning current.

[0040] This invention, by setting a conductive component in conjunction with the lightning arrester 1, increases the lightning interception range and enhances the protection effect on the blades. In specific implementation, a small and easy-to-install lightning conductor strip 21 is used to form an ionization channel, guiding the lightning current to flow onto the metal plate 2. The metal plate 2, arranged along the blade length, acts as a conductor for the lightning current, guiding it to flow into the lightning arrester 1 and the lower guide wire 11, thereby reducing the damage caused by lightning to the blades. At the same time, when the lightning conductor strip 21 is set in conjunction with the metal plate 2, on the one hand, the setting of the lightning conductor strip 21 increases the range and area of ​​lightning current interception, making it easier for the metal plate 2 to intercept lightning, thus enhancing the guiding effect of the lightning current. On the other hand, since the lightning conductor strip 21 is distributed between adjacent metal plates 2, the guiding distance of the lightning conductor strip 21 is shorter, reducing the probability of the lightning conductor strip 21 failing to guide the lightning current, thereby enhancing the lightning interception success rate of the conductive component and the lightning arrester 1.

[0041] In a preferred embodiment of the present invention, the lightning guide strips 21 are evenly distributed at equal intervals on the suction surface of the blade, and the length direction of the lightning guide strips 21 is perpendicular to the length direction of the metal plate 2;

[0042] By arranging the lightning conductor strips 21 at equal intervals on the suction surface of the blades, and with the lightning conductor strips 21 perpendicular to the metal plate 2, the vertical design allows the lightning current to flow into the metal plate 2 along the shortest distance after lightning strike, reducing the flow distance of the lightning current above the lightning conductor strips 21 and thus reducing the damage to the lightning conductor strips 21 caused by lightning strike. On the other hand, since the lightning conductor strips 21 themselves have strong local induced voltage and are prone to lightning strikes, the length of the lightning conductor strips 21 will be reduced to increase the number of them in use, thereby reducing the wear and tear of the lightning conductor strips 21 during lightning protection.

[0043] In a preferred embodiment of the present invention, an extended metal mesh 22 is installed on both sides of the metal plate 2, the extended metal mesh 22 is electrically connected to the metal plate 2, and the extended metal mesh 22 extends to the suction surface and pressure surface of the blade;

[0044] During the guidance of lightning current, the blades themselves possess a certain degree of conductivity due to salt, dirt, and other contaminants on them. When the lightning current is guided towards the metal plate 2 by the lightning conductor, an extended metal mesh 22 is installed between the metal plate 2 and the lightning conductor to enhance the lightning reception efficiency of the metal plate 2. The extended metal mesh 22 serves as a conductor, increasing the lightning reception area of ​​the metal plate 2 and enhancing its efficiency in guiding lightning current. Simultaneously, the metal plate 2 itself generates significant heat during lightning reception. The combination of the extended metal mesh 22 and the metal plate 2 effectively increases the heat dissipation area, facilitating heat dissipation between the metal plate 2 and the extended metal mesh 22. Furthermore, the extended metal mesh 22 extends to the pressure surface of the blade. Since the probability of lightning strikes to the pressure surface is low, the extended metal mesh 22 is less likely to be damaged. Therefore, it is used in conjunction with conductive components to enhance the protection efficiency of the blade.

[0045] In a preferred embodiment of the present invention, the extended metal mesh 22 is a sheet-like structure, and the extended metal mesh 22 is designed in multiples, with multiple extended metal meshes 22 evenly arranged in the length direction of the metal plate 2, and the extended metal mesh 22 and the metal plate 2 are arranged in a fish skeleton shape.

[0046] Because the lightning current may be damaged when it flows on the extended metal mesh 22 due to the electromagnetic force and thermal effect of the lightning current, the extended metal mesh 22 is designed in sheet form and in multiples, and the multiple extended metal meshes 22 are not directly connected. Therefore, when a lightning strike occurs, the number of extended metal meshes 22 through which the lightning current flows is small. When a local extended metal mesh 22 is damaged, it can be directly replaced. Furthermore, the distribution of the extended metal mesh 22, the lightning conductor strip 21, and the metal plate 2 on the blade allows them to form a whole for the overall protection of the blade, while also being separated to enhance the guiding effect of the lightning current and reduce the damage of the lightning current to the lightning protection mechanism.

[0047] It should be noted that in this application, due to the use of the extended metal mesh 22, lightning conductor strip 21, and metal plate 2, the lightning current travels a shorter distance through the extended metal mesh 22 and lightning conductor strip 21 during lightning interception and conduction. This effectively reduces the probability of damage to the extended metal mesh 22 and lightning conductor strip 21. The metal plate 2, primarily used for conducting lightning current, is thicker and has higher heat resistance, thus suffering less damage when lightning current passes through it and can be used for a long time. In contrast, existing technologies only use the extended metal mesh 22 or lightning conductor strip 21 for lightning current interception and guidance. During the lightning interception process, the distance the lightning current travels from the interception position to the lightning arrester 1 is... The lightning current is relatively long, and under the thermal effect of the lightning current, the resistive material and composite baseband used for adhesion in the lightning current guide strip 21 will vaporize and melt, making the lightning current guide strip 21 easy to damage. When only the extended metal mesh 22 is used, the extended metal mesh 22 will also sublimate and melt under the thermal effect, making it more likely to be damaged. Moreover, when the extended metal mesh 22 is repaired locally, the contact resistance at the overlapping position is high and the connection stability is poor when the original extended metal mesh 22 is overlapped with the newly added extended metal mesh 22, which reduces the overall conductivity of the extended metal mesh 22. Therefore, the extended metal mesh 22 is difficult to repair, and if it is completely replaced, it is difficult and has high losses.

[0048] In a preferred embodiment of the present invention, the extended metal mesh 22 and the lightning conductor strip 21 are arranged at intervals;

[0049] By arranging the extended metal mesh 22 and the lightning guide strip 21 at intervals, and combining the performance of the lightning guide strip 21 and the extended metal mesh 22, the number of lightning guide strips 21 and the extended metal mesh 22 used can be reduced while ensuring comprehensive protection of the blades.

[0050] In a preferred embodiment of the present invention, the metal plate 2 is fixedly mounted with uniformly distributed pressure plates 23 on the side near the extended metal mesh 22. The pressure plates 23 are arranged along the thickness direction of the metal plate 2, and an installation groove 24 is formed between two adjacent pressure plates 23. The ends of the extended metal mesh 22 are multi-layered, and the multi-layered extended metal mesh 22 extends into the installation groove 24 respectively.

[0051] When connecting the extended metal mesh 22 to the metal plate 2, in order to minimize the contact resistance between the extended metal mesh 22 and the metal plate 2 and make the lightning current flow more smoothly from the extended metal mesh 22 to the metal plate 2, multiple pressure plates 23 are integrally formed on both sides of the metal plate 2. The pressure plates 23 are all thin metal sheets. During assembly, the ends of the extended metal mesh 22 are folded and inserted one by one into the mounting grooves 24 between the pressure plates 23. This increases the contact area between the extended metal mesh 22 and the pressure plates 23, reduces the contact resistance between them, and facilitates the flow of lightning current.

[0052] In a preferred embodiment of the present invention, the blade is provided with a mounting hole 25, and the pressure plate 23 is provided with a through hole 26. A fastening bolt 27 is installed on the pressure plate 23, and the fastening bolt 27 is threadedly connected to the mounting hole 25 through the through hole 26.

[0053] The fastening bolts 27 serve two purposes. First, during the installation of the extension metal mesh 22, the fastening bolts 27 are used to pressurize the connection between the pressure plate 23 and the blade, increasing the tightness of the connection between the extension metal mesh 22 and the pressure plate 23 while reducing contact resistance. Second, the pressure plate 23 is integrally formed with the metal plate 2, and fixing the pressure plate 23 increases the connection strength between the blade and the metal plate 2. Furthermore, after a lightning strike, when replacing a damaged extension metal mesh 22, the fastening bolts 27 can be loosened locally, allowing the corresponding pressure plate 23 to be relaxed, thus enabling the replacement of the extension metal mesh 22.

[0054] In a preferred embodiment of the present invention, conductive paste is filled between the mounting groove 24 and the extended metal mesh 22 to reduce the contact resistance between the extended metal mesh 22 and the pressure plate 23.

[0055] The application of conductive paste fills the gap between the extended metal mesh 22 and the pressure plate 23, increasing the conductive contact surface. At the same time, under the action of compression force, the oxide layer on the contact surface is broken, which reduces the contact resistance and enhances the conductivity between the extended metal mesh 22 and the pressure plate 23.

[0056] A lightning protection method for wind turbine blades, comprising the following steps:

[0057] S1. Install lightning protection system: When modifying the blade for lightning protection, install multiple lightning rods 1 at intervals at the tip and middle of the blade, and connect the lightning rods 1 to the lower guide wire 11 inside the blade.

[0058] S2. Install metal plate 2: Bend metal plate 2 so that it fits against the leading and trailing edges of the blade, and use mechanical connection methods such as bolts to fix metal plate 2 to the metal surface of lightning arrester 1.

[0059] S3. Install the extension metal mesh 22: The staff manually pry open the pressure plate 23, fold the end of the extension metal mesh 22 and insert it into the installation groove 24 between the pressure plates 23. After applying conductive paste, use the fastening bolts 27 to press the pressure plate 23 and the extension metal mesh 22 between the pressure plates 23, and stick the rest of the extension metal mesh 22 to the blade surface.

[0060] S4. Attach the lightning conductor strip 21: Attach the lightning conductor strip 21 into the gap of the extended metal mesh 22, so that both ends of the lightning conductor strip 21 extend toward the metal plate 2 respectively.

[0061] S5. Lightning protection: When the intensity of the atmospheric electric field around the blade changes, the lightning protection mechanism on the blade forms multiple upward leaders. When the downward leader formed by the thundercloud connects with the upward leader on the blade, a lightning interception channel is formed. Under the guidance of the lightning conductor 21, the extended metal mesh 22 and the metal plate 2, the lightning current is discharged to the ground through the lightning arrester 1 and the lower guide wire 11, thereby preventing lightning from directly striking the blade.

[0062] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A lightning protection mechanism for a wind turbine blade, comprising a lightning arrester (1) installed on the blade and a lower guide wire (11) installed inside the blade, wherein the lightning arrester (1) is electrically connected to the lower guide wire (11), and the lightning arrester (1) cooperates with the lower guide wire (11) to guide the lightning current to the root of the blade; Its features are: It also includes a conductive component mounted on the outer surface of the blade, the conductive component being used to guide the lightning current to the lightning arrester (1). The conductive component includes at least two metal plates (2), which are fixedly installed on the leading edge and trailing edge of the blade, respectively, and the metal plates (2) are fixedly connected to the lightning arrester (1). Lightning guide strip (21), the lightning guide strip (21) is a segmented guide strip, the lightning guide strip (21) is fixedly pasted on the suction surface of the blade, and the lightning guide strip (21) is located between two metal plates (2); The lightning guide strips (21) are evenly distributed at equal intervals on the suction surface of the blade, and the length direction of the lightning guide strips (21) is perpendicular to the length direction of the metal plate (2). Both sides of the metal plate (2) are equipped with extended metal mesh (22), which is electrically connected to the metal plate (2) and extends to the suction surface and pressure surface of the blade; The extended metal mesh (22) is a sheet-like structure. Multiple extended metal meshes (22) are evenly arranged along the length of the metal plate (2). The extended metal meshes (22) and the metal plate (2) are arranged in a fish skeleton shape. The extended metal mesh (22) and the lightning conductor strip (21) are arranged alternately; The metal plate (2) is fixedly installed with uniformly distributed pressure plates (23) on the side near the extended metal mesh (22). The pressure plates (23) are arranged along the thickness direction of the metal plate (2), and an installation groove (24) is formed between two adjacent pressure plates (23). The ends of the extended metal mesh (22) are multi-layered, and the multi-layered extended metal mesh (22) extends into the installation groove (24) respectively.

2. The lightning protection mechanism for wind turbine blades according to claim 1, characterized in that: The blade has an installation hole (25), and the pressure plate (23) has a through hole (26). The pressure plate (23) is fitted with a fastening bolt (27), and the fastening bolt (27) is threadedly connected to the installation hole (25) through the through hole (26).

3. The lightning protection mechanism for wind turbine blades according to claim 2, characterized in that: The mounting groove (24) and the extended metal mesh (22) are filled with conductive paste to reduce the contact resistance between the extended metal mesh (22) and the pressure plate (23).

4. A method for lightning protection of wind turbine blades, characterized in that: This method is applicable to the lightning protection mechanism for a wind turbine blade as described in claim 3, and the method includes the following steps: S1. Install lightning protection system: When modifying the blade for lightning protection, install multiple lightning rods (1) at intervals at the tip and middle of the blade, and connect the lightning rods (1) to the lower guide wire (11) inside the blade. S2. Install metal plate (2): Bend the metal plate (2) so that the metal plate (2) fits against the leading and trailing edges of the blade, and use bolts to mechanically connect the metal plate (2) to the metal surface of the lightning arrester (1). S3. Install the extension metal mesh (22): The staff manually pry open the pressure plate (23), fold the end of the extension metal mesh (22) and insert it into the installation groove (24) between the pressure plates (23). After applying conductive paste, the staff uses fastening bolts (27) to press the pressure plate (23) and the extension metal mesh (22) between the pressure plates (23) tightly, and then paste the rest of the extension metal mesh (22) onto the blade surface. S4. Attaching the lightning conductor strip (21): Attach the lightning conductor strip (21) to the gap in the extended metal mesh (22) and make both ends of the lightning conductor strip (21) extend toward the metal plate (2); S5. Lightning protection: When the intensity of the atmospheric electric field around the blade changes, the lightning protection mechanism on the blade forms multiple upward leaders. When the downward leader formed by the thundercloud is connected with the upward leader on the blade, a lightning interception channel is formed. Under the guidance of the lightning conductor (21), the extended metal mesh (22) and the metal plate (2), the lightning current is discharged to the ground through the lightning arrester (1) and the lower guide line (11), thereby preventing lightning from directly hitting the blade.

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