Method for improving reliability of blade lightning protection system and wind power lightning protection blade

Abstract

The invention relates to the technical field of wind power blade lightning protection, in particular to a method for improving the reliability of a blade lightning protection system, by changing the structure and the arrangement mode of a medium-voltage cable, the cross section of the medium-voltage cable close to a blade tip part is reduced, the space of the blade tip part is effectively utilized, and the cross section area of a down lead is increased, so that the lightning channel resistance is reduced, and the reliability of the blade lightning protection system is improved. And the through-current capability of the downlead is enhanced. The structure of the medium-voltage cable is adjusted, the matched blade body lightning arrester support is assisted to restrain the degree of freedom in the circumferential direction of the medium-voltage cable, the possibility that the cable falls off is reduced, the mechanical reliability of the blade body lightning arrester support is enhanced, the space utilization rate in a blade tip cavity is improved, an insulating layer is thickened, and the insulating performance of the down lead is improved. And meanwhile, the contact resistance of the down lead and the lightning arrester is reduced, the through-current capability is improved, and the risk of lightning protection failure is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of wind turbine blade lightning protection, and specifically provides a method for improving the reliability of a blade lightning protection system and a wind turbine lightning protection blade. Background Art

[0002] Wind turbine blades are a very important component of wind power generation systems. Their main function is to convert the kinetic energy of wind into mechanical energy and drive the generator rotor to generate electricity. However, in areas with frequent lightning activities, wind turbine blades are easily targeted by lightning, causing serious damage or even destroying the entire wind turbine system. Therefore, taking a series of lightning protection measures is crucial to ensure the safe operation of wind turbine blades.

[0003] For wind turbine blades, the lightning protection principle of the blade lightning rod is to introduce lightning through the lightning rod on the surface of the blade, and the current is conducted to the metal flange or other structure at the root of the blade through the lightning protection wire (down conductor) inside the blade, and then the current is guided to the ground through the wind turbine's own lightning protection system to restrain lightning and protect the blade. The installation and positioning of the blade lightning rod base seriously affects the lightning protection effect of the blade lightning protection system. The positioning of the lightning rod base has very high requirements. The axial position, chord position, angle and height of the lightning rod base must meet the design requirements. If the position or angle is offset, the subsequent installation of the lightning rod will also be offset, making it difficult to install the lightning rod. There is a potential for increased resistance, poor lightning connection, and blades being struck by lightning, causing large economic losses.

[0004] The existing down conductor connections at the base of the blade cross lightning rod are all disconnected and then crimped separately. This connection method may cause the down conductor to break at the crimping point after long-term operation of the wind turbine, resulting in lightning protection failure. In addition, there are special-shaped down conductor connection structures at both ends of the base. The connection method between the special-shaped structure and the base is mostly welding or one-piece injection molding. The former has risks in structural reliability, and the latter has high cost. The blade branch lightning rod base also has a special-shaped down conductor connection structure, and the connection method is also welding or one-piece injection molding. The former has risks in structural reliability, and the latter has high cost and is inconvenient to replace.

[0005] In the drainage process of the entire lightning protection system, the down conductor is a key component. It is arranged in the blade cavity. From the root to the tip, the space in the blade cavity gradually becomes smaller, and the cavity includes conductive substances such as water vapor and dust. Therefore, it poses a considerable challenge to the insulation performance, drainage capacity and mechanical reliability of the down conductor. In the current related design work, the down conductor is only considered to be simply connected with the blade tip lightning rod and the blade body lightning rod. Its insulation performance, drainage capacity and mechanical reliability have not been fully explored and avoided.

[0006] After searching, CN113833616A discloses a lightning protection system for wind turbine blades, which is arranged in the wind turbine blade shell, including a web, a cable, a blade body base, a blade body lightning receptor, a blade tip base and a blade tip lightning receptor; the web is supported in the middle area inside the wind turbine blade shell, the cable is arranged on the trailing edge side of the web, the number of blade body bases is several, and several blade body bases are arranged at intervals on the trailing edge side along the length direction of the wind turbine blade, the blade body lightning receptors are arranged one by one on the blade body base, the blade tip base is arranged at the tip of the wind turbine blade, the cable passes through the blade body base in turn and is connected to the blade tip base, and the blade tip lightning receptor is connected to the blade tip base; the system has a firm connection, good insulation, fast installation, and is easy to replace and repair. This patent does not highlight the connection of the blade tip down conductor.

[0007] CN210686192U discloses a wind turbine blade with lightning protection function, and proposes an innovative solution for the connection between the blade tip lightning receptor and the blade body lightning receptor. The solution directly abandons the independent blade tip lightning receptor and the blade body lightning receptor, directly uses the lightning receptor to increase the lightning receptor area, and uses the wire to transfer the current of the lightning receptor to the blade internal down conductor, and finally leads it to the ground through the hub. The protection point of this patent is to increase the contact area, and does not consider the drainage capacity and insulation performance of the main down conductor.

[0008] In summary, how to design a method to improve the reliability of the blade lightning protection system, enhance the insulation performance, current capacity and reliability of the system, so as to improve the lightning protection reliability and stability of wind turbine blades is a problem that needs to be solved urgently. Summary of the invention

[0009] In order to solve the above problems, the present invention provides a method for improving the reliability of the blade lightning protection system, by adjusting the structure of the medium-voltage cable, and using a matching blade lightning receptor support to constrain the circumferential freedom of the medium-voltage cable, reducing the possibility of cable falling off, enhancing the mechanical reliability of the blade lightning receptor support, improving the space utilization rate in the blade tip cavity, thickening the insulation layer, and improving the insulation performance of the down conductor. At the same time, the contact resistance between the down conductor and the lightning receptor is reduced, the current carrying capacity is improved, and the risk of lightning protection failure is reduced.

[0010] In the area near the blade tip, flat conductors are used as medium-voltage cables, which increases the thickness of the conductor insulation layer and enhances the insulation performance of the system, while reducing the current skin effect and enhancing the current-carrying capacity. At the same time, a blade lightning arrester support with flat holes that is suitable for flat conductors is used to constrain the conductor circumferentially and enhance structural reliability. Integrated molding and connection are used to further enhance structural reliability.

[0011] In order to achieve the above object, the technical solution adopted by the present invention is: The present invention provides a method for improving the reliability of a blade lightning protection system. By changing the structure and arrangement of a medium-voltage cable, the cross-section of the medium-voltage cable near the blade tip becomes smaller, the space at the blade tip is effectively utilized, and the cross-sectional area of ​​the down conductor is increased to reduce the resistance of the lightning channel and enhance the current-carrying capacity of the down conductor.

[0012] The present invention creatively adjusts the cross-sectional structure of the medium voltage cable for the first time, reducing the cross-sectional area so as to effectively utilize the narrow space at the blade tip. This breaks the barriers of stereotyped thinking for the existing circular cable structure.

[0013] Furthermore, the medium voltage cable is designed and formed in an integrated manner according to the cross-sectional dimensions of the inner wall of the blade tip lightning receptor, the root dimensions of the blade body lightning receptor close to the blade tip lightning receptor, and the internal space dimensions of the blade tip. The arrangement of this structure is to make the entire medium voltage cable more consistent with the internal structure of the blade, and to make the assembly with the internal structure more stable, while effectively utilizing the space, maximizing the cross-sectional area of ​​the down conductor, thereby reducing the lightning channel resistance and enhancing the current carrying capacity of the down conductor.

[0014] Furthermore, the medium-voltage cable stacks multiple single-layer flat structures in the vertical direction (z direction) to form a multi-layer stacked flat conductor, and the multi-layer stacked flat conductor extends into the interior of the blade to form a main medium-voltage cable. Branch medium-voltage cables are installed on both sides of the main medium-voltage cable, and the branch medium-voltage cables are flat structures or circular structures in cross section. The medium-voltage cable of the present invention is set as a flat structure, and the branch medium-voltage cables connected thereto can be set as traditional round conductors or all replaced with flat structures. It can be selected according to actual needs, and round conductors can be selected for parts of the blade with large space. At the same time, the single-layer flat conductors are stacked using an integrated molding method and connected to the blade tip lightning arrester, which enhances the mechanical reliability of the wind turbine blade lightning protection system.

[0015] Furthermore, the single-layer flat structures of the multi-layer stacked flat conductors are insulated to form a medium voltage cable, and the ratio of the cross-section thickness of the single-layer flat structure to the cross-section thickness of the interlayer insulation layer is 6-8:2-4. This arrangement increases the insulation performance as much as possible while ensuring the flow capacity, thereby increasing the reliability of the medium voltage cable in the entire blade tip.

[0016] Furthermore, one end of the main medium-voltage cable passes through a blade body lightning arrester support and is connected to a blade tip lightning arrester, and the other end is connected to a low-voltage cable round conductor by a crimping tube.

[0017] Furthermore, the cross section of the blade air terminal support is a cross section, including a main body and a medium voltage cable installation wing extending outward from the main body, and a flat cross section through hole is arranged at the center of the medium voltage cable installation wing to adapt to the installation of the medium voltage cable. The design of the flat cross section through hole allows the flat conductor to pass through and then be crimped, thereby constraining the conductor of the medium voltage cable circumferentially and reducing the possibility of the conductor falling off.

[0018] Furthermore, the blade body lightning receptor support 2 includes a convex structure.

[0019] Furthermore, the convex structure is used to fix and connect the high-voltage down conductor. The arc center position of the convex structure is offset by a certain distance to open a through hole, and a slot is opened outside the through hole. The stripped high-voltage down conductor is placed into the through hole from the slot edge and pressed tightly. This structure avoids the situation in the existing design where the high-voltage down conductor is disconnected and crimped separately. The reliability of the integrated down conductor structure is enhanced, and there are no special-shaped structural parts, which reduces the cost and increases the reliability of use.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The method of improving the reliability of the blade lightning protection system of the present invention starts from the practical problem that the internal space of the blade, especially the blade tip space is limited, changes the structure of the down conductor, adjusts the structure of the medium voltage cable to a flat structure for the first time, and also adaptively adjusts the mounting hole structure of the blade body lightning receptor support, so that the entire down conductor can effectively utilize the space in the blade tip part in view of the complex environment of the blade tip part, enhance the insulation performance of the down conductor, reduce the skin effect of the lightning current, improve the current conduction capacity of the lightning current, and reduce the risk of lightning protection failure. In addition, when used, the down conductor reduces the possibility of cable falling off and enhances mechanical reliability.

[0021] In addition, the present invention also takes into account the installation problem of the down conductor without the need for a flat structure, and designs two blade lightning rod supports. Instead of cutting off the branch down conductor, the blade lightning rod is directly crimped and pressed with the branch down conductor, which can reduce the design of the base special structure, simplify the process, reduce the manufacturing cost of the lightning protection system, and increase the reliability of the entire branch down conductor. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the overall structure of a wind turbine blade lightning protection system according to the method for improving the reliability of a blade lightning protection system as described in the present invention.

[0023] Figure 2 A schematic diagram of a single-layer flat structure of a medium voltage cable in the method for improving the reliability of a blade lightning protection system according to the present invention.

[0024] Figure 3 A schematic structural diagram of the multi-layer stacked flat conductors of a medium voltage cable in the method for improving the reliability of a blade lightning protection system according to the present invention.

[0025] Figure 4 A schematic structural diagram of a blade lightning arrester support of a medium voltage cable according to the method for improving the reliability of a blade lightning protection system of the present invention.

[0026] Figure 5 This is a structural schematic diagram of the blade lightning arrester support 2 of the medium voltage cable of the method for improving the reliability of the blade lightning protection system described in the present invention.

[0027] Figure 6 A comparison of the round and flat conductors of medium voltage cables at the blade tip.

[0028] In the figure: 1-low-voltage cable round conductor, 2-crimping tube, 3-medium-voltage cable, 31-flat conductor layer, 32-insulating layer, 4-rivet, 5-blade body lightning arrester support one, 51-body, 52-medium-voltage cable mounting wing, 53-flat section through hole, 6-bolt, 7-blade tip lightning arrester, 8-medium-voltage cable, 9-blade body lightning arrester support two, 91-through hole, 92-slot, 100-blade web, 200-circular section conductor. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the following Figure 1-6 It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention. Example 1

[0030] like Figure 1-Figure 3 As shown, this embodiment starts with an improved wind turbine blade lightning protection system and structure. By changing the structure and arrangement of the medium-voltage cable, the cross-section of the medium-voltage cable 3 near the blade tip is reduced, the space at the blade tip is effectively utilized, and the cross-sectional area of ​​the down conductor is increased to reduce the lightning channel resistance and enhance the current carrying capacity of the down conductor.

[0031] Specifically, the medium voltage cable 3 is designed according to the cross-sectional dimensions of the inner wall of the blade tip lightning receptor 7, the root dimensions of the blade body lightning receptor close to the blade tip lightning receptor 7, and the internal space dimensions of the blade tip, and is formed in an integrated manner.

[0032] Since the existing circular cross-section conductors have uniform dimensions in all directions, in order to adapt to the narrow overall space at the blade tip, the y-direction dimension is relatively large and the z-direction dimension is relatively small. The space at the blade tip is narrow, and when a circular cross-section conductor is used, the thickness of the insulation layer on the surface of the conductor will be greatly limited, resulting in a decrease in the insulation performance of the blade lightning protection system down conductor and an increase in the probability of blade damage. The wind turbine blade lightning protection system of this embodiment uses a flat conductor as a medium-voltage cable 3. Under the same internal space dimensions of the blade tip, the use of a flat conductor can increase the cross-sectional area of ​​the down conductor, reduce the resistance of the lightning channel, and enhance the current carrying capacity of the down conductor. The flat conductor used can significantly increase the thickness of the insulation layer while ensuring that the thickness of the insulation layer at each part of the conductor is uniform, thereby ensuring the insulation performance of the blade lightning protection system down conductor and enhancing the reliability of the blade lightning protection system.

[0033] In this embodiment, the medium voltage cable 3 stacks multiple single-layer flat structures in the vertical direction (z direction) to form a multi-layer stacked flat conductor, and the multi-layer stacked flat conductor extends into the interior of the blade to form a main medium voltage cable. A branch medium voltage cable 8 is installed on both sides of the main medium voltage cable. The branch medium voltage cable 8 is a flat structure or a circular structure in cross section. The branch medium voltage cable 8 is arranged on both sides of the main medium voltage cable, and the branch medium voltage cable is connected to the blade body lightning arrester support 2 9. Specifically: one end of the medium voltage cable 3 is connected to the low voltage cable round conductor 1 by using a crimping tube 2; the medium voltage cable 3 and the branch medium voltage cable 8 can be riveted by using rivets 4, and the remaining blade body lightning arrester supports 2 9 are connected.

[0034] The single-layer flat structure of the multi-layer stacked flat conductors is insulated to form a medium voltage cable, that is, a flat conductor layer 31 and an insulating layer 32 are formed, and the ratio of the cross-sectional thickness of the single-layer flat structure to the cross-sectional thickness of the interlayer insulating layer is 6-8:2-4, and preferably 7:3 in this embodiment. This arrangement increases the insulation performance as much as possible while ensuring the current flow capacity, thereby increasing the reliability of the medium voltage cable in the entire blade tip area.

[0035] One end of the main medium voltage cable passes through the blade body lightning receptor support 5 and is connected to the blade tip lightning receptor 7, and the other end is connected to the low voltage cable round conductor 1 by using the crimping tube 2. Figure 4 As shown, the cross section of the blade lightning arrester support 5 is a cross section, including a main body 51 and a medium voltage cable installation wing 52 extending outward from the main body 51, and a flat cross-section through hole 53 is arranged in the center of the medium voltage cable installation wing to adapt to the installation of the medium voltage cable 3.

[0036] The blade body lightning rod support 5 used has a flat-section through hole, and the flat conductor is crimped after passing through, which constrains the conductor circumferentially and reduces the possibility of the conductor falling off; at the same time, the single-layer flat conductor is stacked by an integrated molding method and connected to the blade tip lightning rod, which enhances the mechanical reliability of the wind turbine blade lightning protection system.

[0037] like Figure 5As shown, the blade lightning rod support 2 9 of this embodiment includes a convex structure. The convex structure is used to fix and connect the high-voltage down conductor. The arc surface center position of the convex structure is offset by a certain distance to open a through hole 91, and a slot 92 is opened on the outside of the through hole. The stripped high-voltage down conductor is placed in the through hole 91 from the side of the slot 92 and pressed tightly. After the through hole is opened at a certain distance from the center position of the arc surface of the cylindrical cross lightning rod base, a side slot is opened to pass the high-voltage down conductor integrally, which can avoid the high-voltage down conductor being disconnected and then crimped, thereby improving the flow capacity of the high-voltage down conductor. At the same time, the high-voltage down conductor increases the structural reliability of the lightning protection system, reduces the risk of lightning protection failure, and improves the safety performance of the wind turbine operation; the arc surface center position of the cylindrical blade branch lightning rod base is offset by a certain distance to open a through hole, which is directly crimped with the branch down conductor and pressed in a certain way, which can reduce the design of the base special-shaped structure, simplify the process, and reduce the manufacturing cost of the lightning protection system.

[0038] The medium-voltage cable of the wind turbine blade lightning protection system adopts a flat conductor, and the first blade body lightning arrester has a flat hole, through which the medium-voltage cable passes and is crimped. The improved system and structure of the present invention can effectively utilize the space in the blade tip part under the conditions of narrow space at the blade tip part, a lot of conductive materials, and a high probability of lightning strike, increase the insulation thickness of the wire, improve the insulation performance of the down conductor at this part, and reduce the skin effect of the lightning current, improve the current conduction capacity of the lightning current, reduce the risk of lightning protection failure, and enhance the mechanical reliability of the system.

[0039] like Figure 6 As shown, the surface of the whole multi-layer flat-section conductor shown in the figure is subjected to polyurethane injection molding insulation treatment to obtain an insulation layer, and the down conductor is placed between the two blade webs 100 to complete the arrangement of the flat-section down conductor in the internal space of the blade tip. At the same time, the arrangement of the flat conductor and the round conductor in the blade cavity is compared. Compared with the insulation layer of the round-section conductor 200, the flat conductor can increase the thickness of its insulation layer 32 while ensuring the cross-sectional area of ​​the conductor, and is more suitable for the characteristics of the tip of the wind turbine blade having a smaller size in the z direction and a larger size in the y direction.

[0040] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

[0041] The above specific implementations of the present invention do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for improving the reliability of a blade lightning protection system, characterized in that: By changing the structure and arrangement of the medium voltage cable (3), the cross section of the medium voltage cable (3) near the blade tip is reduced, the space at the blade tip is effectively utilized, the cross section area of ​​the down conductor is increased, the lightning channel resistance is reduced, and the current carrying capacity of the down conductor is enhanced.

2. The method for improving the reliability of a blade lightning protection system according to claim 1, characterized in that: The medium voltage cable (3) is designed in size according to the cross-sectional size of the inner wall of the blade tip lightning receptor (7), the root size of the blade body lightning receptor close to the blade tip lightning receptor (7), and the internal space size of the blade tip, and is integrally formed.

3. The method for improving the reliability of a blade lightning protection system according to claim 2, characterized in that: The medium-voltage cable (3) stacks a plurality of single-layer flat structures in a vertical direction to form a multi-layer stacked flat conductor, and the multi-layer stacked flat conductor extends into the interior of the blade to form a main medium-voltage cable. Branch medium-voltage cables (8) are installed on both sides of the main medium-voltage cable (3), and the branch medium-voltage cables (8) are flat structures or circular structures in cross section.

4. The method for improving the reliability of a blade lightning protection system according to claim 3, characterized in that: The single-layer flat structures of the multi-layer stacked flat conductors are insulated to form a medium voltage cable (3), and the ratio of the cross-section of the single-layer flat structure to the cross-section thickness of the interlayer insulation layer is 6-8:2-4.

5. The method for improving the reliability of a blade lightning protection system according to any one of claims 1 to 4, characterized in that: One end of the main medium-voltage cable (3) passes through a blade body lightning receptor support (5) and is connected to a blade tip lightning receptor (7), and the other end is connected to a low-voltage cable round conductor (1) by means of a crimping tube (2).

6. The method for improving the reliability of a blade lightning protection system according to claim 5, characterized in that: The branch medium voltage cables (8) are arranged on both sides of the main medium voltage cable, and the branch medium voltage cables (8) are connected to the second blade air terminal support (9).

7. The method for improving the reliability of a blade lightning protection system according to claim 5, characterized in that: The blade air terminal support (5) has a cross-section, comprising a main body (51) and a medium-voltage cable installation wing (52) extending outward from the main body (51), and a flat-section through hole (53) is provided at the center of the medium-voltage cable installation wing (52) to accommodate the installation of a medium-voltage cable (8).

8. The method for improving the reliability of a blade lightning protection system according to claim 6, characterized in that: The blade body lightning arrester support 2 (9) comprises a convex structure.

9. The method for improving the reliability of a blade lightning protection system according to claim 8, characterized in that: The convex structure is used for fixing and connecting the high-voltage down conductor. The arc surface center position of the convex structure is offset by a certain distance to form a through hole (91). A slot (92) is formed outside the through hole (91). The stripped high-voltage down conductor is placed into the through hole (91) from the slot edge and pressed tightly.

10. A wind power lightning protection blade, characterized in that: The method for improving the reliability of a blade lightning protection system according to any one of claims 1 to 9 is used for preparation.

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