Lightning conductor for fan blade and preparation method of lightning conductor

Abstract

The invention discloses a lightning conductor for a fan blade and a preparation method thereof, and belongs to the technical field of lightning conductors, the lightning conductor for the fan blade comprises a conductor unit, a shielding unit and an insulating layer; the shielding unit is Fe < 3 + > dynamic chelating silica gel; the Fe < 3 + > dynamic chelating silica gel is crosslinked with a tannic acid-Fe < 3 + > complex; the molar ratio of tannic acid to Fe < 3 + > in the tannic acid-Fe < 3 + > complex is 1: (2-3). The introduction of the silica gel can avoid adverse effects caused by small air gaps generated when the conductor units and the insulating layers are directly compounded, the overall bending resistance is improved, an electric field can be uniformly distributed through dynamic chelating of iron ions, partial discharge is prevented, and the iron ions are combined with phenolic hydroxyl groups in tannic acid to form dynamic chelating bonds, so that the service life of the cable is prolonged. Under electric shock, valence state transformation is achieved, surrounding heat is absorbed, silica gel defects are repaired, the service life of silica gel is prolonged, and the service life of the lightning conductor is also prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of lightning protection wires, and in particular relates to a lightning protection wire for wind turbine blades and a preparation method thereof. Background Art

[0002] Wind turbine blade lightning conductors, also known as downconductors, are primarily installed inside the blades. By connecting the blade tip lightning receptors and the tower grounding grid, they form a wind turbine lightning protection system. They play a crucial role in wind turbine lightning protection systems, significantly reducing the likelihood of lightning strikes. Their primary function is that when lightning strikes the blade tip lightning receptor, the lightning current is conducted to the ground via the downconductor, effectively preventing damage to the blades and other wind turbine components, ensuring the proper operation of the wind turbine system. With the continuous increase in installed wind turbine capacity and the increasing length of wind turbine blades, the number of lightning conductors required has increased accordingly, and their importance in wind turbine equipment is becoming increasingly prominent.

[0003] During operation, the blades of a wind turbine will swing and bend under the influence of wind. When the blades rotate to the top, the wind thrust is the greatest, and the blades bend and deform to the greatest extent. When the blades rotate to the bottom, close to the ground, the wind thrust decreases, the blades deform and rebound, and the deformation amplitude reaches a minimum. As the blade length increases, the swing amplitude and deformation of the blades will also increase. During one rotation of the wind turbine blade, the blades bend, rebound, and bend again, forming a cyclical swing. Since the lightning conductor for the wind turbine blades is fixed inside the blades, it swings toward the blades, causing the lightning conductor inside the blades to bend and swing accordingly, and its frequency is consistent with the frequency of the blades bending and rebounding.

[0004] When a lightning conductor undergoes long-term bending and rebound, the conductor in the lightning conductor will easily break due to long-term stress and bending fatigue. Under the influence of long-term high-load lightning and strong electric fields, the possibility of the lightning conductor breaking during bending deformation becomes greater. At this time, when lightning strikes the lightning rod, the current is blocked at the break in the lightning conductor and cannot be conducted into the earth. The huge energy of the lightning is converted into heat, causing fire and explosion at the break of the conductor. In severe cases, the entire blade will break and fall, causing huge losses.

[0005] Existing technologies mainly focus on monitoring broken wire faults or monitoring the improvement of lightning conductors. However, this method can only detect faults and then repair the broken parts by replacing blades or repairing them, but it cannot fundamentally solve the broken wire problem. The safety of the blades is still not guaranteed, and the service life of the lightning conductor is greatly reduced. Summary of the Invention

[0006] The purpose of the present invention is to provide a lightning conductor for wind turbine blades and a preparation method thereof, so as to solve the problem of the lightning conductor breaking due to long-term lightning strikes and bending deformation, and to extend the service life of the lightning conductor.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] In the first aspect, the present invention provides a lightning protection wire for wind turbine blades, comprising a conductor unit, a shielding unit and an insulating layer; the shielding unit is Fe 3+ Dynamic chelating silicone gel;

[0009] Fe 3+ Dynamic chelated silica gel cross-linked with tannic acid-Fe 3+ Complex; the tannic acid-Fe 3+ Tannic acid and Fe in the complex 3+ The molar ratio is 1:(2~3).

[0010] Preferably, the raw material of the insulating layer is tetrafluoroethylene-ethylene copolymer.

[0011] Preferably, the thickness of the insulating layer is 0.15 to 0.25 mm.

[0012] By adopting the above-mentioned technical solution, the lightning conductor of the present invention is extruded with silicone rubber between the conductor unit and the insulation layer. Silicone rubber itself has excellent flexibility and a small bending radius, making the resulting lightning conductor more flexible overall, thereby reducing the mechanical stress on the conductor unit when the wind turbine blade is bent, and avoiding fatigue fracture caused by repeated bending. Compared with conventional shielding polymers, it has a higher elastic modulus and aging resistance, allowing the lightning conductor to maintain structural integrity after repeated bending and huge lightning strike energy. The introduction of the silicone rubber layer can better and more evenly distribute the stress generated during bending, improving stability after long-term bending.

[0013] Furthermore, the silica gel used in the present invention is Fe 3+ Dynamic chelating silica gel, Fe 3+ Chelation can impart a certain degree of conductivity to the silicone gel. When a conductor comes into direct contact with an insulating layer, due to its uneven surface and twisted structure, tiny air gaps form. These tiny air gaps have a dielectric constant much lower than that of solid insulating materials. At the same voltage, they experience higher electric field strengths, triggering partial discharges and ultimately leading to insulation breakdown. The silicone gel of the present invention can fill these tiny air gaps. Its conductive silicone gel shielding unit can also evenly distribute the electric field, preventing partial discharge. This is particularly true under the long-term vibration of wind turbine blades, which can prevent breakdown and deterioration of the insulation interface.

[0014] At the same time, traditional semi-conductive layers mostly use cross-linked polymers with high content of conductive carbon black. However, when the carbon black filling reaches a certain level, the hardness and brittleness of the material increase significantly, which easily leads to bending stress concentration and thermomechanical fatigue. Under the long-term bending vibration of the wind turbine blade, the high-hardness semi-conductive layer is prone to cracks at the conductor-insulation interface, making it unable to withstand the huge short-term high current carrying capacity caused by lightning strikes. 3+ The chelation of silicone gel makes it conductive without relying on a large amount of carbon black particles. It can effectively avoid the increase in rigidity caused by fillers, thereby greatly improving the bending resistance of the lightning conductor.

[0015] Furthermore, the Fe 3+ The chelation is done by tannic acid as a bridge to connect Fe 3+ and silica gel matrix, Fe 3+ By combining with the phenolic hydroxyl groups in tannic acid to form a dynamic chelate bond, Fe 3+ Can absorb electrons and convert into Fe 2+ At the same time, it will absorb the surrounding heat to achieve the purpose of cooling and protecting the fan blades. After the lightning strike, Fe 2+ It will gradually absorb the free radicals in the system and convert them into Fe 3+ , slowly returning to its original state, Fe 3+ / Fe 2+ The valence state switching can effectively repair the micro cracks in silicone gel caused by the high temperature of lightning strikes, thereby effectively protecting the lightning conductor for a long time and increasing the service life of the lightning conductor.

[0016] Preferably, Fe 3+ Dynamic chelating silicone gel includes the following raw materials in parts by weight:

[0017] 100 parts of hydroxy silicone oil-based gel;

[0018] Tannic acid-Fe 3+ 6-10 parts of complex;

[0019] 0.5-1 part of carbon nanotubes;

[0020] 0.2-0.3 parts of cross-linking agent;

[0021] 0.1 to 0.2 parts of catalyst.

[0022] Preferably, the viscosity of the hydroxy silicone oil is 5000 to 10000 mPa·s.

[0023] Preferably, the crosslinking agent includes a combination of one or more of tetramethoxysilane, methyltrimethoxysilane, propylmethoxysilane, vinyltrimethoxysilane and methyltriacetoxysilane.

[0024] Preferably, the catalyst comprises a combination of one or more of dibutyltin diacetate, dibutyltin dilaurate and stannous octoate.

[0025] By adopting the above technical solution, the Fe 3+ Dynamic chelated silicone gel uses hydroxy silicone oil as the matrix material. Under the action of catalyst and cross-linking agent, hydroxy silicone oil is condensed to form silicone gel. On the one hand, it can better react with the silanol groups on the surface of carbon nanotubes, reduce the interfacial tension between carbon nanotubes and silicone gel matrix, improve the dispersion uniformity, and thus effectively inhibit the structuring phenomenon of silicone gel and improve the bending resistance of the material; on the other hand, tannic acid-Fe 3+ The dynamic bonds formed by the complex can combine with the hydroxyl network of hydroxy silicone oil to construct a multiple dynamic cross-linking system, thereby significantly improving the mechanical properties of the material and better integrating Fe 3+ Introduced into silica gel. The addition of tannic acid can not only complex Fe 3+ , helping to achieve Fe 3+ The change in valence state can also enhance the interfacial bonding between the silicone gel and the conductor unit and the insulating layer, thereby improving long-term stability.

[0026] And in Fe 3+ Carbon nanotubes are also added to the dynamic chelated silica gel. The one-dimensional tubular structure and high aspect ratio of carbon nanotubes can form a three-dimensional network skeleton in the silica gel, thereby improving the tensile strength and tear resistance of the material. At the same time, the tannic acid-Fe 3+ The complex network gives the silicone gel a certain degree of self-repairing ability, and the dynamic bonds can be quickly reconstructed after damage, restoring structural integrity. The polar groups on the surface of the carbon nanotubes are hydrogen-bonded with the hydroxyl silicone oil matrix and tannic acid molecules in the silicone gel, enhancing interfacial bonding, better dispersing external loads, and improving the bending resistance of the lightning rod.

[0027] At the same time, the addition of carbon nanotubes can form a continuous conductive network in the silica gel, and tannic acid-Fe 3+ The iron ions in the complex can provide additional charge transfer channels. The redox activity of the iron ions can also cooperate with the π-π conjugated structure of the carbon nanotubes to promote electron hopping conduction, better disperse the charge, increase the current carrying capacity of the lightning conductor, withstand multiple long-term lightning energy impacts, quickly disperse the lightning current, reduce local Joule heat during lightning strikes, and reduce carbonization damage to the lightning conductor.

[0028] Preferably, Fe 3+ The raw materials of the dynamic chelating silicone gel also include polyethylene glycol; the added amount of the polyethylene glycol is 10 to 15 parts.

[0029] Preferably, the molecular weight of polyethylene glycol is 400-800.

[0030] By adopting the above technical solution, Fe 3+ The physical entanglement of the dynamic cross-linking coordination bonds and carbon nanotubes in the dynamic chelating silicone gel will affect the dynamic cross-linking density, thereby affecting the valence change process of iron ions under the action of a strong electric field. The fixed network of carbon nanotubes will also hinder the self-healing behavior of the dynamic bonds, and after a long time, breakage due to bending will occur.

[0031] Because the Fe 3+ Dynamic chelating silica gel can also introduce polyethylene glycol. The introduction of polyethylene glycol segments can improve the dispersion of carbon nanotubes in silica gel and reduce the agglomeration tendency of carbon nanotubes. On the other hand, it can help to build a dynamic cross-linking network and regulate the tannic acid-Fe 3+ The complex forms a cross-linked network with relaxation behavior, which reduces energy dissipation during bending. Its flexible chain segments can suppress the expansion of cracks by absorbing energy, significantly improving the material's fatigue resistance and better improving the bending resistance of lightning rods.

[0032] Preferably, Fe 3+ Dynamic chelating silica gel is prepared according to the following method:

[0033] Add soluble trivalent iron salt to the tannic acid aqueous solution and ultrasonically react for 5 to 10 minutes to obtain tannic acid-Fe 3+ Complex; Mix hydroxy silicone oil with polyethylene glycol, add carbon nanotubes, stir and mix for 20 to 40 minutes, and then add tannic acid-Fe 3+ The complex, cross-linking agent and catalyst are stirred for 2 to 3 hours, and finally allowed to stand at room temperature for 20 to 30 hours.

[0034] Preferably, the soluble ferric salt includes one or more of ferric chloride, ferric nitrate nonahydrate, ferric sulfate nonahydrate and ferric pyrophosphate.

[0035] Preferably, in Fe 3+ The technical effects of the present invention can be achieved without adding polyethylene glycol during the preparation of the dynamic chelating silica gel.

[0036] By adopting the above technical solution, a large amount of phenolic hydroxyl groups in tannic acid complex iron ions to form a complex. The low-viscosity hydroxyl silicone oil has a low degree of polymerization, a short molecular chain, and suppressed cross-linking density. The formed silicone gel has good elasticity and good molding ability, and the obtained silicone gel has good bending resistance.

[0037] Preferably, the raw material of the conductor unit is a graphene composite metal conductor; the metal conductor includes any one of a copper conductor and an aluminum alloy conductor.

[0038] Preferably, the mass fraction of graphene is 2-3%.

[0039] Preferably, the graphene composite metal conductor is prepared by any one of ball milling, powder metallurgy and oxidation-reduction method.

[0040] By adopting the above technical solution, the selection of lightning conductor material will directly affect the efficiency of lightning current conduction, the mechanical properties of the blades, and the long-term durability. Although general metal conductors have excellent electrical conductivity, they have poor fatigue resistance and are prone to corrosion, which will seriously affect the service life of wind turbine blades. Therefore, the conductor unit raw material of the present invention is a graphene composite metal conductor material. The surface of the graphene sheet can be evenly covered with a metal layer to form a continuous three-dimensional conductive network. This composite structure expands the conduction path of the lightning current from a single channel of traditional metal to a multi-level coordinated path, significantly reducing the resistivity, thereby enhancing the carrying capacity of the lightning current, effectively dispersing the instantaneous current generated by lightning strikes, and avoiding the risk of melting due to local overheating.

[0041] Graphene's two-dimensional π-π conjugated structure also imparts excellent electromagnetic shielding effectiveness to the composite material. When a lightning strike occurs, the graphene sheets attenuate the electromagnetic wave energy through a dual mechanism of dielectric loss and magnetic loss, channeling the current to the grounding system. The graphene composite metal also significantly improves its bending fatigue resistance, inhibiting crack growth and absorbing cyclic load energy, thereby significantly extending the service life of the lightning conductor.

[0042] Preferably, the lightning conductor for wind turbine blades further comprises a self-status remote monitoring unit; the self-status remote monitoring unit detects current and / or temperature anomalies in the lightning conductor through a wireless monitoring device, issues an early warning, and performs line break monitoring.

[0043] By implementing this technical solution, the self-status remote monitoring unit can measure abnormal changes in the lightning conductor in real time, triggering a warning signal that is then transmitted to the control system, accurately locating the breakpoint. This ensures visibility into the status of the wind turbine lightning protection system and manages risks. This early warning of potential corrosion and loosening of the lightning conductor reduces delamination damage to the blade composite material caused by lightning strikes, extending blade service life.

[0044] In a second aspect, the present invention provides a method for preparing a lightning conductor for a wind turbine blade, comprising the following process steps:

[0045] S1. twisting the graphene composite metal conductor to obtain a conductor unit;

[0046] S2. Insulated extruded tetrafluoroethylene - ethylene copolymer to obtain a tetrafluoroethylene - ethylene copolymer coating, extruded between the conductor unit and the tetrafluoroethylene - ethylene copolymer coating to form a shielding unit of Fe3 + dynamic chelating silicone gel;

[0047] S3. Radiation cross-linking of the tetrafluoroethylene-ethylene copolymer coating layer yields an insulating layer, and finally a self-status remote monitoring unit is installed to obtain a lightning conductor for the wind turbine blades.

[0048] Beneficial effects of the present invention:

[0049] 1. The lightning protection wire for wind turbine blades of the present invention is extruded with Fe between the conductor unit and the insulation layer. 3+ Dynamic chelation silicone gel can avoid the adverse effects caused by tiny air gaps when the conductor unit and the insulation layer are directly compounded. It can also use its excellent flexibility and small bending radius to improve the bending resistance of the lightning conductor. In addition, silicone gel undergoes dynamic chelation of iron ions. On the one hand, it brings a certain conductivity, evenly distributes the electric field, and prevents local discharge, thereby avoiding the occurrence of breakdown. On the other hand, it can combine with the phenolic hydroxyl groups in tannic acid to form dynamic chelation bonds, realize valence state transformation under electric shock, absorb surrounding heat, repair silicone gel defects, and increase the service life of silicone gel.

[0050] 2. Fe used in the present invention 3+ Dynamic chelating silicone gel contains carbon nanotubes, which can form a three-dimensional network skeleton in the silicone gel, thereby improving the tensile strength and tear resistance of the material; it can also form a continuous conductive network in the silicone gel to better disperse the charge, increase the current carrying capacity of the lightning conductor, quickly disperse the lightning current, and reduce the carbonization damage of the lightning conductor.

[0051] 3. Fe used in the present invention 3+ In order to improve the performance of dynamic chelated silica gel, polyethylene glycol is also introduced. Polyethylene glycol can improve the dispersion of carbon nanotubes in silica gel, reduce the agglomeration tendency of carbon nanotubes, and regulate the tannic acid-Fe 3+ The complex forms a relaxation behavior of the cross-linked network, and its flexible chain segments can inhibit the expansion of cracks by absorbing energy, significantly improving the fatigue resistance of the material and better improving the bending resistance of the lightning rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The present invention will be further described below with reference to the accompanying drawings.

[0053] Figure 1 This is a schematic structural diagram of a lightning protection wire for a wind turbine blade according to embodiment 1 of the present invention;

[0054] Figure 2 It is a schematic diagram of the fan blade swing;

[0055] Figure 1 Middle: 1. Conductor unit; 2. Shielding unit; 3. Insulation layer. DETAILED DESCRIPTION

[0056] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0057] Preparation Example

[0058] Preparation Example 1, a Fe 3+ Dynamic chelating silica gel is prepared according to the following method:

[0059] Add ferric chloride to the tannic acid aqueous solution, wherein the molar ratio of tannic acid to ferric chloride is 1:3, and ultrasonically react for 5 minutes to obtain tannic acid-Fe 3+ complex;

[0060] 8 g of carbon nanotubes (diameter 5-15 nm, length 0.5-2 μm) were added to 1000 g of hydroxy silicone oil (average viscosity 6000 mPa·s) and stirred for 30 min. Then, 80 g of the tannic acid-Fe 3+ The complex, 2 g of tetramethoxysilane and 2 g of dibutyltin diacetate were stirred for 2 h, and finally allowed to stand at room temperature for 24 h to obtain the product.

[0061] Preparation Example 2, a Fe 3+ The dynamic chelating silica gel is different from Preparation Example 1 only in that the molar ratio of tannic acid to ferric chloride is 1:2.

[0062] Preparation Example 3 and Preparation Example 4, a Fe 3+ The dynamic chelating silica gel is different from Preparation Example 1 only in that the raw material ratio is adjusted, as shown in Table 1:

[0063] Table 1 Formula of Preparation Example 1, Preparation Example 3 and Preparation Example 4

[0064] Preparation Example 1 Preparation Example 3 Preparation Example 4 Hydroxyl silicone oil / g 1000 1000 1000 Carbon nanotubes / g 8 10 5 <![CDATA[Tannic acid-Fe 3+ complex / g]]> 80 60 100 Tetramethoxysilane / g 2 3 2 Dibutyltin diacetate / g 2 2 1

[0065] Preparation Example 5, a Fe 3+ The dynamic chelating silica gel is different from the preparation example 1 only in that tannic acid-Fe 3+ The amount of the complex added was 30 g.

[0066] Preparation Example 6, a Fe 3+ The dynamic chelating silica gel is different from the preparation example 1 only in that tannic acid-Fe 3+ The amount of the complex added was 120 g.

[0067] Preparation Example 7, a Fe 3+The dynamic chelating silica gel is different from Preparation Example 1 only in that the molar ratio of tannic acid to ferric chloride is 1:1.

[0068] Preparation Example 8, a Fe 3+ The dynamic chelating silica gel is different from Preparation Example 1 only in that the molar ratio of tannic acid to ferric chloride is 1:4.

[0069] Preparation Example 9, a Fe 3+ Dynamic chelating silica gel is prepared according to the following method:

[0070] 8 g of carbon nanotubes (diameter 5-15 nm, length 0.5-2 μm) were added to 1000 g of hydroxy silicone oil (average viscosity 6000 mPa·s) and stirred for 30 min. Then, 80 g of ferric chloride aqueous solution, 2 g of tetramethoxysilane and 2 g of dibutyltin diacetate were added in sequence. The mixture was stirred for 2 h and allowed to stand at room temperature for 24 h.

[0071] Preparation Example 10: A silica gel was prepared according to the following method:

[0072] 8 g of carbon nanotubes (diameter 5-15 nm, length 0.5-2 μm) were added to 1000 g of hydroxy silicone oil (average viscosity 6000 mPa·s) and stirred for 30 min. Then, 80 g of the above-obtained tannic acid aqueous solution, 2 g of tetramethoxysilane and 2 g of dibutyltin diacetate were added in sequence. The mixture was stirred for 2 h and allowed to stand at room temperature for 24 h.

[0073] Preparation Example 11, a Fe 3+ The dynamic chelating silica gel is different from Preparation Example 1 only in that no carbon nanotubes are added.

[0074] Preparation Example 12, a Fe 3+ Dynamic chelating silica gel is prepared according to the following method:

[0075] Add ferric chloride to the tannic acid aqueous solution, wherein the molar ratio of tannic acid to ferric chloride is 1:3, and ultrasonically react for 5 minutes to obtain tannic acid-Fe 3+ complex;

[0076] 1000g of hydroxy silicone oil (average viscosity of 6000mPa·s) and 120g of polyethylene glycol (average molecular weight of 400) were mixed, 8g of carbon nanotubes (diameter of 5-15nm, length of 0.5-2μm) were added, and stirred for 30min. Then, 80g of the tannic acid-Fe 3+ The complex, 2 g of tetramethoxysilane and 2 g of dibutyltin diacetate were stirred for 2 h, and finally allowed to stand at room temperature for 24 h to obtain the product.

[0077] Preparation Example 13, a Fe 3+ The dynamic chelating silica gel is different from Preparation Example 12 only in that the amount of polyethylene glycol added is 100 g.

[0078] Preparation Example 14, a Fe 3+ The dynamic chelating silica gel is different from Preparation Example 12 only in that the amount of polyethylene glycol added is 150 g.

[0079] Example

[0080] Example 1: A lightning conductor for a wind turbine blade is prepared according to the following process steps:

[0081] S1. Twisting the graphene-composite copper conductors to obtain a conductor unit, wherein the mass fraction of the composite graphene is 3%;

[0082] S2. Insulation extrusion tetrafluoroethylene - ethylene copolymer to obtain a tetrafluoroethylene - ethylene copolymer coating layer, the conductor unit and the tetrafluoroethylene - ethylene copolymer coating layer extruded between the Fe prepared in Example 1 3+ Dynamic chelating silicone gel forms a shielding unit;

[0083] S3. The insulating layer is obtained by radiation cross-linking the tetrafluoroethylene-ethylene copolymer coating. The average thickness of the insulating layer is 0.2 mm. Finally, a self-status remote monitoring unit is installed to obtain a lightning conductor for the wind turbine blade.

[0084] Example 2, a lightning conductor for wind turbine blades, is different from Example 1 only in that the same amount of Fe prepared in Example 2 is used. 3+ Dynamic chelating silica gel replaces the Fe prepared in Preparation Example 1 3+ Dynamic chelating silicone gel.

[0085] Example 3, a lightning conductor for wind turbine blades, is different from Example 1 only in that the same amount of Fe prepared in Example 3 is used. 3+ Dynamic chelating silica gel replaces the Fe prepared in Preparation Example 1 3+ Dynamic chelating silicone gel.

[0086] Example 4, a lightning conductor for wind turbine blades, is different from Example 1 only in that the same amount of Fe prepared in Example 4 is used. 3+ Dynamic chelating silica gel replaces the Fe prepared in Preparation Example 1 3+ Dynamic chelating silicone gel.

[0087] Example 5, a lightning conductor for wind turbine blades, is different from Example 1 only in that the same amount of Fe prepared in Example 5 is used. 3+ Dynamic chelating silica gel replaces the Fe prepared in Preparation Example 1 3+ Dynamic chelating silicone gel.

[0088] Example 6, a lightning conductor for wind turbine blades, is different from Example 1 only in that the same amount of Fe prepared in Example 6 is used. 3+ Dynamic chelating silica gel replaces the Fe prepared in Preparation Example 1 3+ Dynamic chelating silicone gel.

[0089] Example 7, a lightning conductor for wind turbine blades, differs from Example 1 only in that an equal amount of Fe prepared in Example 11 is used. 3+ Dynamic chelating silica gel replaces the Fe prepared in Preparation Example 1 3+ Dynamic chelating silicone gel.

[0090] Example 8, a lightning conductor for wind turbine blades, which differs from Example 1 only in that an equal amount of Fe prepared in Example 12 is used. 3+ Dynamic chelating silica gel replaces the Fe prepared in Preparation Example 1 3+ Dynamic chelating silicone gel.

[0091] Example 9, a lightning conductor for wind turbine blades, differs from Example 1 only in that an equal amount of Fe prepared in Example 13 is used. 3+ Dynamic chelating silica gel replaces the Fe prepared in Preparation Example 1 3+ Dynamic chelating silicone gel.

[0092] Example 10, a lightning conductor for wind turbine blades, differs from Example 1 only in that an equal amount of Fe prepared in Example 14 is used. 3+ Dynamic chelating silica gel replaces the Fe prepared in Preparation Example 1 3+ Dynamic chelating silicone gel.

[0093] Comparative Example

[0094] Comparative Example 1, a lightning conductor for wind turbine blades, differs from Example 1 only in that an equal amount of Fe prepared in Example 7 is used. 3+ Dynamic chelating silica gel replaces the Fe prepared in Preparation Example 1 3+ Dynamic chelating silicone gel.

[0095] Comparative Example 2, a lightning conductor for wind turbine blades, differs from Example 1 only in that an equal amount of Fe prepared in Example 8 is used. 3+ Dynamic chelating silica gel replaces the Fe prepared in Preparation Example 1 3+ Dynamic chelating silicone gel.

[0096] Comparative Example 3, a lightning conductor for wind turbine blades, which differs from Example 1 only in that an equal amount of Fe prepared in Example 9 is used. 3+ Dynamic chelating silica gel replaces the Fe prepared in Preparation Example 1 3+ Dynamic chelating silicone gel.

[0097] Comparative Example 4, a lightning conductor for wind turbine blades, differs from Example 1 only in that an equal amount of Fe prepared in Preparation Example 10 is used. 3+ Dynamic chelating silica gel replaces the Fe prepared in Preparation Example 1 3+ Dynamic chelating silicone gel.

[0098] Comparative Example 5, a lightning conductor for wind turbine blades, differs from Example 1 only in that an equal amount of copper conductor is used to replace the graphene composite copper conductor.

[0099] Comparative Example 6: A lightning conductor for a wind turbine blade is prepared according to the following process steps:

[0100] S1. Twisting the graphene-composite copper conductors to obtain a conductor unit, wherein the mass fraction of the composite graphene is 3%;

[0101] S2. Tetrafluoroethylene-ethylene copolymer is extruded on the outside of the conductor unit for insulation, and radiation cross-linking is performed to obtain an insulation layer with an average thickness of 0.2 mm. Finally, a self-status remote monitoring unit is installed to obtain a lightning conductor for the wind turbine blades.

[0102] Performance testing

[0103] Sample preparation: Take a 50 cm long lightning conductor for wind turbine blades obtained in the examples and comparative examples, install one end of the conductor on a fixed chuck and the other end on a rotating chuck, and hang a weight with a load of W = 5N (500gf) at the lower end of the conductor.

[0104] Performance test: The sample is rotated by rotating the rotary chuck, applying a ±180° twist to the portion between the fixed and rotating chucks of the lightning conductor. The rotating chuck first rotates +180° and returns to its original position, then rotates -180° and returns to its original position, and repeats this cycle. The twisting speed is 30 times / min, and one round trip in each direction is counted as one twist. Then, while repeatedly twisting, a voltage of several volts is continuously applied to the shield layer from both ends of the lightning conductor. The wire is considered broken when the current value drops by 20% compared to the start of the test.

[0105] The test results are shown in Table 2:

[0106] Table 2 Performance test results

[0107]

[0108] According to Table 2, combined with Example 1 and Comparative Example 6, it can be seen that the bending life of Example 1 is significantly increased compared with Comparative Example 6. The reason is that the difference between Example 1 and Comparative Example 6 is that there is Fe between the conductor unit and the insulation layer. 3+Dynamic chelating silicone gel can help fill the tiny air gap between the conductor unit and the insulation layer, better disperse the stress generated during bending, and improve the overall bending resistance.

[0109] Combining Example 1, Example 5, Example 6 and Comparative Example 3, it can be seen that the bending life of Example 5, Example 6 and Comparative Example 3 is reduced compared with Example 1. The reason is that Example 5, Example 6 and Comparative Example 3 have a significant effect on the tannic acid-Fe 3+ The amount of complex added was adjusted, and when tannic acid-Fe 3+ When the amount of complex added is reduced, the dynamic chelate bond in the silicone gel is reduced, which will increase the rigidity of the material, reduce the heat absorption effect under the action of current, and reduce the bending life of the material under the action of strong electric field. In comparative example 3, no tannic acid-Fe was added. 3+ The conductivity of the complex also decreased, and the overall performance decreased more significantly. 3+ When the amount of complex added increases, the cross-linking density inside the silicone gel will increase significantly, which is not conducive to improving flexibility and causes the bending resistance of the material to decrease.

[0110] Combining Example 1 and Example 8, it can be seen that the bending life of Example 8 is increased compared with Example 1. The reason is that Example 8 has a 3+ Polyethylene glycol segments are also introduced into the preparation process of dynamic chelating silica gel. Polyethylene glycol can improve the dispersion of carbon nanotubes in silica gel and also cooperate with tannic acid-Fe 3+ Complexes reduce bending stress concentration, and flexible segments can absorb the energy generated during bending to inhibit crack expansion, significantly improving the material's fatigue resistance and bending resistance.

[0111] In conjunction with Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 4, it can be seen that the bending life of Comparative Example 1, Comparative Example 2 and Comparative Example 4 is reduced compared to Example 1. The reason is that the molar ratio between tannic acid and iron ion is adjusted in Comparative Example 1, Comparative Example 2 and Comparative Example 4, the iron ion content added in Comparative Example 1 decreases, the dynamic chelate bond of iron ion formed decreases, and iron ion is difficult to improve the carrying capacity of lightning arrester by absorbing electrons under strong electric field and is difficult to absorb the heat generated around, thereby causing fatigue resistance to decrease and bending resistance to decrease. Comparative Example 4 does not contain iron ions, and the performance degradation is more obvious, and the electrical conductivity also decreases, and the dispersion effect on charge also decreases. When the iron ion content increases, the iron ions will gradually coordinate with the polar groups in the hydroxy silicone oil matrix in large quantities, the dynamic bond content decreases, and the cross-linking density increases, which will cause the flexibility of the material to decrease and the bending resistance to decrease.

[0112] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0113] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A lightning conductor for wind turbine blades, characterized in that: It includes a conductor unit, a shielding unit and an insulating layer; the shielding unit is Fe 3+ Dynamic chelating silicone gel; The Fe 3+ Dynamic chelated silica gel cross-linked with tannic acid-Fe 3+ Complex; the tannic acid-Fe 3+ Tannic acid and Fe in the complex 3+ The molar ratio is 1:(2~3).

2. The lightning conductor for wind turbine blades according to claim 1, characterized in that: The Fe 3+ Dynamic chelating silicone gel includes the following raw materials in parts by weight: 100 parts of hydroxy silicone oil; Tannic acid-Fe 3+ 6-10 parts of complex; 0.5-1 part of carbon nanotubes; 0.2-0.3 parts of cross-linking agent; 0.1 to 0.2 parts of catalyst.

3. The lightning conductor for wind turbine blades according to claim 2, characterized in that: The viscosity of the hydroxy silicone oil is 5000 to 10000 mPa·s.

4. The lightning conductor for wind turbine blades according to claim 2, characterized in that: The Fe 3+ The raw materials of the dynamic chelating silicone gel also include polyethylene glycol; the added amount of the polyethylene glycol is 10 to 15 parts.

5. The lightning conductor for wind turbine blades according to claim 4, characterized in that: The Fe 3+ Dynamic chelating silica gel is prepared according to the following method: Add soluble trivalent iron salt to the tannic acid aqueous solution and ultrasonically react for 5 to 10 minutes to obtain tannic acid-Fe 3+ Complex; Mix hydroxy silicone oil with polyethylene glycol, add carbon nanotubes, stir and mix for 20 to 40 minutes, and then add tannic acid-Fe 3+ The complex, cross-linking agent and catalyst are stirred for 2 to 3 hours, and finally allowed to stand at room temperature for 20 to 30 hours.

6. The lightning conductor for wind turbine blades according to claim 1, characterized in that: The raw material of the conductor unit is a graphene composite metal conductor; the metal conductor includes any one of a copper conductor and an aluminum alloy conductor.

7. The lightning conductor for wind turbine blades according to claim 6, characterized in that: The mass fraction of the graphene is 2-3%.

8. The lightning conductor for wind turbine blades according to claim 1, characterized in that: The raw material of the insulating layer is tetrafluoroethylene-ethylene copolymer.

9. The lightning conductor for wind turbine blades according to claim 1, characterized in that: The lightning conductor for wind turbine blades further comprises a self-status remote monitoring unit; the self-status remote monitoring unit detects abnormal current and / or temperature in the lightning conductor through a wireless monitoring device, issues an early warning, and performs line break monitoring.

10. A method for preparing a lightning conductor for a wind turbine blade according to any one of claims 1 to 9, characterized in that: The process steps include: S1. twisting the graphene composite metal conductor to obtain a conductor unit; S2. Insulation extrusion tetrafluoroethylene-ethylene copolymer to obtain tetrafluoroethylene-ethylene copolymer coating layer, between the conductor unit and the tetrafluoroethylene-ethylene copolymer coating layer extrusion Fe 3+ Dynamic chelating silicone gel forms a shielding unit; S3. Radiation cross-linking of the tetrafluoroethylene-ethylene copolymer coating layer yields an insulating layer, and finally a self-status remote monitoring unit is installed to obtain a lightning conductor for the wind turbine blades.

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