A 35 kV torsion-resistant cable for wind turbines

Abstract

The present invention relates to the technical field of cables, and specifically relates to a 35 kV torsion-resistant cable for a wind turbine, which is composed of a cable core and a ground wire. The cable core and the ground wire are covered and fixed by a torsion-resistant strengthening layer and an outer sheath layer; the torsion-resistant cable provided by the present invention has a perfect appearance after 10,000 times of 1080° forward and reverse torsion tests at normal temperature and 5,000 times of 1080° forward and reverse torsion tests at low temperature. After torsion, a voltage of AC 50 Hz 73.5 kV is applied for 60 minutes of voltage withstand, and no breakdown phenomenon occurs, having excellent anti-torsion performance.

Description

Technical Field

[0001] The invention relates to the technical field of cables, in particular to a torsion-resistant cable for a 35kV wind turbine generator. Background Art

[0002] With the rapid development of my country's economy, the acceleration of industrialization and urbanization, energy demand has grown rapidly. As people pay more attention to environmental protection, clean energy, energy conservation and emission reduction, they optimize the energy structure, reduce the proportion of petrochemical energy, and vigorously develop new energy. Renewable energy such as wind energy, photovoltaic solar energy, biomass energy and geothermal energy have ushered in development opportunities.

[0003] The development of the wind power industry has given rise to the demand for special cables for wind turbines. For example, the power and control signal cables in the uppermost section of the tower need to rotate continuously with the wind turbine, which puts higher requirements on the cable's anti-torsion performance. Summary of the invention

[0004] Purpose of the invention: In view of the above technical problems, the present invention proposes a torsion-resistant cable for a 35kV wind turbine.

[0005] The technical solutions adopted are as follows:

[0006] A 35kV torsion-resistant cable for a wind turbine generator, comprising a cable core and a ground wire, wherein the cable core and the ground wire are fixed by being coated with an anti-torsion reinforcement layer and an outer sheath layer;

[0007] The outer sheath layer is prepared from the following raw materials in parts by weight:

[0008] 90-100 parts of polyvinyl chloride, 5-10 parts of liquid amino-terminated nitrile rubber, 5-10 parts of star-shaped comb-shaped polybutadiene-g-polymethyl methacrylate copolymer, 10-20 parts of silica nanotubes, 3-5 parts of composite lead stabilizer, 5-10 parts of carbon black, 0.1-1 parts of paraffin, 1-2 parts of stearic acid, 1-3 parts of phosphate flame retardant, 0.1-0.5 parts of antioxidant and 20-40 parts of plasticizer.

[0009] Furthermore, the cable core comprises a conductor, a conductor shielding layer, an EPR insulating layer and an insulating shielding layer from the inside to the outside.

[0010] Among them, the conductor is of the 5th type of soft copper coaxial stranded wire structure, and the production process is drawing - bunch stranding - double stranding. The single wire for drawing is 1.75 ± 0.05 mm. Under the conditions of an annealing coefficient of 95%, a speed of 16 - 22 m / s, and 14 drawing passes, it is drawn into a single wire of 0.38 mm. Then, an automatic high - speed bunching machine is used to bunch and strand the 0.38 - mm wires. The single - wire arrangement form of 2×8 + 1×6 (2 strands of 8 wires of 0.38 mm and 1 strand of 6 wires of 0.38 mm are stranded together) is used to control the pitch - diameter ratio within 18 - 20 times for bunching and stranding. The stranding direction is left - hand. Then, it is further double - stranded through a 6 + 12 + 18 / 500 type cage strander. According to the arrangement of 1 + 6 + 12, the inner - layer pitch - diameter ratio is controlled within 18 - 20 times, and the outer - layer pitch - diameter ratio is controlled within 16 - 18 times. The stranding directions are all left - hand, forming the conductor;

[0011] The bunching and stranding are carried out in the single - wire arrangement form of 2×8 + 1×6, and the double - stranding arrangement is 1 + 6 + 12. This structural design helps to improve the overall stability and torsional resistance of the cable. The control of the pitch - diameter ratio ensures the tightness and uniformity of the stranded wire, thus enhancing the torsional strength of the cable. The same - direction stranding means that all the stranding directions are left - hand. This same - direction stranding can reduce the internal stress of the cable during torsion, improving the stability and durability of the cable.

[0012] Furthermore, the torsional - resistance strengthening layer is woven from Kevlar fibers at 8 spindles / 2000D, with 4 spindles on each side (front and back), the pitch being 110 - 130 mm, and cross - weaving. Each spindle is evenly spaced for weaving, and the weaving density is 20 - 26%. The design of 4 spindles on each side (front and back) makes the Kevlar fibers evenly distributed in the cable, which can provide balanced support when the cable is twisted, avoiding damage caused by excessive local stress.

[0013] Furthermore, the preparation method of the star - shaped comb - like polybutadiene - g - polymethyl methacrylate copolymer is as follows:

[0014] The star - shaped polybutadiene is synthesized into star - shaped epoxidized polybutadiene by the formic acid - hydrogen peroxide in - situ method. The star - shaped epoxidized polybutadiene then undergoes an incomplete esterification reaction with 2 - bromoisobutyryl bromide under the action of water to obtain star - shaped brominated polybutadiene. Then, using star - shaped brominated polybutadiene as the initiator, cuprous chloride and copper chloride as the catalyst and regulator respectively, and N,N,N',N",N" - pentamethyldiethylenetriamine as the ligand, the polymerization of methyl methacrylate is initiated by the ATRP method to finally obtain the star - shaped comb - like polybutadiene - g - polymethyl methacrylate copolymer.

[0015] Further, the molar ratio of epoxy groups to 2-bromo isobutyryl bromide in the star-shaped epoxidized polybutadiene is 1:0.1-0.8. Controlling the molar ratio of epoxy groups to 2-bromo isobutyryl bromide in the star-shaped epoxidized polybutadiene can control the number of residual epoxy groups in the star-shaped epoxidized polybutadiene. Controlling the number of epoxy groups can control the crosslinking density of epoxy groups and amino groups in the outer sheath layer, achieving the purpose of improving the tensile properties of the outer sheath.

[0016] Further, the molar ratio of bromine atoms to methyl methacrylate in the star-shaped brominated polybutadiene is 1:10-40.

[0017] Further, the preparation method of the silica nanotubes is as follows:

[0018] The sepiolite is crushed and washed with deionized water, first added to hydrochloric acid solution for impurity removal, the obtained reaction solution is filtered and the collected solid is washed thoroughly with deionized water, then added to the polyvinylpyrrolidone solution, ultrasonic oscillation treatment is carried out and then sodium borohydride is added, the obtained reaction solution reacts at 50-70°C for 1-5 h, and finally the product is collected, washed thoroughly with deionized water and dried.

[0019] Further, the phosphate flame retardant is any one or a combination of tris(isopropylphenyl) phosphate, tris(2-chloroethyl) phosphate, tris(2-chloropropyl) phosphate.

[0020] Further, the antioxidant is any one or a combination of antioxidant 1010, antioxidant 1076, antioxidant 245, antioxidant 168.

[0021] Further, the plasticizer is any one or a combination of dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, benzyl butyl phthalate, diisononyl phthalate.

[0022] Advantages of the present invention:

[0023] The present invention provides a 35 kV wind turbine torsion-resistant cable. The conductor is stranded by using a single-wire arrangement form of 2×8+1×6 and a composite stranding arrangement of 1+6+12. This structural design helps to improve the overall stability and torsion resistance of the cable. The control of the pitch diameter ratio ensures the tightness and uniformity of the stranded wire, thereby enhancing the torsional strength of the cable. The same-direction stranding means that all the stranding directions are left-handed. This same-direction stranding can reduce the internal stress of the cable during torsion, improving the stability and durability of the cable;

[0024] The torsional reinforcement layer is woven from Kevlar fibers at 8 spindles / 2000D, with 4 spindles on each side (front and back). The pitch is 110 - 130 mm, and it is cross-woven. Each spindle is evenly spaced and woven. The weaving density is 20 - 26%. The design of 4 spindles on each side makes the Kevlar fibers evenly distributed in the cable, which can provide balanced support when the cable is twisted, avoiding damage caused by excessive local stress.

[0025] The outer sheath layer in the present invention has excellent tensile properties, which can significantly improve the torsional resistance of the cable. The star-shaped comb-like polybutadiene-g-polymethyl methacrylate copolymer has a special star-shaped comb-like structure, has good compatibility with PVC, and also contains polymethyl methacrylate side chains and epoxy groups. The star-shaped comb-like structure inhibits the strong interaction between the polar C-Cl bonds of the PVC chains, and can enhance the outer sheath material by dissipating the energy of external forces. Polymethyl methacrylate is conducive to promoting the brittle-ductile transition of the PVC matrix, generating a large amount of free volume and increasing the movement opportunities of macromolecules, so the tensile properties are improved. The epoxy groups can cross-link with the epoxy groups in the liquid terminal amino nitrile rubber, thus playing a positive role in enhancing the tensile properties of the outer sheath layer. The liquid terminal amino nitrile rubber has good compatibility with PVC, easily forms a cellular structure coated with PVC, and is dispersed in the PVC continuous phase to form a "sea-island" structure, inducing the generation of crazes and shear bands and absorbing energy, playing a toughening and anti-torsion effect. The silica nanotubes not only have a reinforcing effect, but also, as an efficient and environmentally friendly flame retardant, can synergistically improve the fire and flame retardant properties of the outer sheath layer with phosphate flame retardants. Of course, the above mechanism is only a speculation based on experimental results, and there may be omissions and errors, but it will not have a negative impact on the creativity of the present invention. Brief Description of the Drawings

[0026] Figure 1 It is a schematic structural diagram of the cable provided in Example 1, and the labels in the figure represent respectively:

[0027] 1 - outer sheath layer, 2 - ground wire, 3 - torsional reinforcement layer, 4 - insulation shielding layer, 5 - EPR insulation layer, 6 - conductor shielding layer, 7 - conductor. Detailed Embodiments

[0028] For those not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase. The technologies not mentioned in the present invention refer to the prior art. Unless otherwise specified, the following examples and comparative examples are parallel tests and adopt the same treatment steps and parameters. Example 1

[0029] A 35 kV wind turbine cable with torsional resistance, and the specific structure is shown in Figure 1, which consists of a cable core and a ground wire 2. The cable core and the ground wire 2 are covered and fixed by a torsion-resistant strengthening layer 3 and an outer sheath layer 1;

[0030] The cable core includes a conductor 7, a conductor shielding layer 6, an EPR insulation layer 5, and an insulation shielding layer 4 from the inside to the outside;

[0031] Among them, the conductor 7 is the 5th type of soft copper coaxial stranded wire structure, and the production process is drawing - bunch stranding - multiple stranding. The single wire for drawing is 1.75 ± 0.05 mm. Under the conditions of an annealing coefficient of 95%, a speed of 16 - 22 m / s, and 14 drawing passes, it is drawn into a single wire of 0.38 mm. Then, an automatic high-speed bunching machine is used to bunch and strand the 0.38 mm wires. The pitch diameter ratio is controlled at 18 - 20 times in the single wire arrangement form of 2×8 + 1×6, and the bunching direction is left-handed. Then, it is further multi-stranded by a 6 + 12 + 18 / 500 type cage strander. According to the arrangement of 1 + 6 + 12, the inner layer pitch ratio is controlled at 18 - 20 times, and the outer layer pitch diameter ratio is controlled at 16 - 18 times. The bunching directions are all left-handed, forming the conductor 7;

[0032] The conductor shielding layer 6 is formed by winding an aluminum-plastic composite tape, and the insulation shielding layer 4 is formed by covering a PET electrical insulation film;

[0033] The torsion-resistant strengthening layer 3 is woven from Kevlar fibers at 8 spools / 2000D, with 4 spools on each side, the pitch is 110 - 130 mm, cross-woven, and evenly spaced and arranged for each spool. The weaving density is 20 - 26%;

[0034] By weight, the outer sheath layer 1 is prepared from the following raw materials:

[0035] 100 parts of polyvinyl chloride, 8 parts of liquid terminal amino nitrile rubber, 6 parts of star-shaped comb-shaped polybutadiene-g-polymethyl methacrylate copolymer, 15 parts of silicon dioxide nanotubes, 3 parts of composite lead stabilizer, 10 parts of carbon black, 0.5 part of paraffin, 2 parts of stearic acid, 2 parts of flame retardant IPPP, 0.25 part of antioxidant 1010, 25 parts of plasticizer DOP.

[0036] The preparation method of the star-shaped comb-shaped polybutadiene-g-polymethyl methacrylate copolymer is as follows:

[0037] 9.39 g of a cyclohexane solution of 1,3-butadiene (1,3-butadiene: cyclohexane = 1:8) is sequentially added, V : V),(2.85 mL of a cyclohexane solution of n-butyllithium (2 mol / L)) and 0.6 mL of THF were pressured into a dry round-bottom flask with nitrogen and mixed well. The reaction solution was reacted in a 50 °C constant temperature water bath under nitrogen protection for 3 h. Then, 1.42 mL of a cyclohexane solution of SiCl4 (1.1 mol / L) was added, and the reaction continued under insulation for 4 h. After returning to room temperature, the reaction solution was precipitated with anhydrous ethanol. The obtained precipitate was dried in vacuo at 50 °C to constant weight to obtain the crude product. The crude product was extracted in a Soxhlet extractor with acetone for 12 h to obtain star-shaped polybutadiene. 5 g of star-shaped polybutadiene was dissolved in 100 mL of toluene, 1.74 g of formic acid was added, and 4.2 g of hydrogen peroxide was titrated within 30 min in a 40 °C constant temperature water bath. After maintaining the reaction for 2 h, the reaction solution was washed with deionized water and the organic phase was separated. Ethanol was added for precipitation. The obtained precipitate was dried in vacuo at 50 °C to constant weight to obtain star-shaped epoxidized polybutadiene and the epoxy degree was calculated. Under nitrogen protection, 5 g of star-shaped epoxidized polybutadiene was added to 50 mL of THF and stirred to dissolve it completely. Then, triethylamine, 50 mL of THF, and 1 mL of deionized water were added. 2-Bromo-2-methylpropionyl bromide was added dropwise within 30 min under ice bath conditions. The molar ratio of epoxy groups, triethylamine, and 2-bromo-2-methylpropionyl bromide in star-shaped epoxidized polybutadiene was 1:0.5:0.4. After reacting at room temperature for 48 h, it was passed through an activated alumina column with chloroform as the eluent. Ethanol was added to the eluent for precipitation. The obtained precipitate was dried in vacuo at 50 °C to constant weight to obtain star-shaped brominated polybutadiene. The bromine content in it was determined by chemical titration method. Star-shaped brominated polybutadiene, copper(I) chloride, copper(II) chloride, N,N,N',N",N"-pentamethyldiethylenetriamine with a molar ratio of 1:1:0.2:1 were mixed well and then methyl methacrylate was added. The molar ratio of bromine atoms in star-shaped brominated polybutadiene to methyl methacrylate was controlled to be 1:20. After repeating the operations of liquid nitrogen freezing-vacuum pumping-thawing 3 times, the reaction was carried out in a 50 °C constant temperature water bath for 8 h. The polymerization was terminated with an ice-salt bath. After adding an appropriate amount of THF to dissolve the product, a neutral alumina column was used with THF as the eluent. Ethanol was added to the eluent for precipitation. The obtained precipitate was dried in vacuo at 50 °C to constant weight to obtain star-shaped comb-shaped polybutadiene-g-poly(methyl methacrylate) copolymer.

[0038] The preparation method of the silicon dioxide nanotubes is as follows:

[0039] 100 g of sepiolite was crushed and passed through an 80-mesh sieve, and then washed thoroughly with deionized water to remove water-soluble impurities. Then, it was added to a sufficient amount of 6 mol / L hydrochloric acid solution and stirred at room temperature for 12 h for impurity removal. After the obtained reaction solution was filtered, the solid was collected and washed thoroughly with deionized water until neutral and dried. 6 g of the obtained product was added to 200 mL of a 2.91 wt% polyvinylpyrrolidone solution. After ultrasonic oscillation treatment for 30 min, 12 g of sodium borohydride was added. The obtained reaction solution was reacted at 65 °C for 3 h. Finally, the solid product was collected by centrifugation, washed thoroughly with deionized water, and dried.

[0040] The preparation method of the above outer sheath layer is as follows:

[0041] Weigh each component according to the formula and mix them evenly, ensuring that the mixing temperature does not exceed 120 °C. After the material temperature drops to room temperature, place it on an open plasticizer for plasticization. The temperature of the front roller is 160 ± 10 °C, and the temperature of the rear roller is 140 ± 10 °C. After kneading for 5 minutes, discharge the material, then preheat it on a flat vulcanizer at 160 °C and 5 MPa for 5 minutes, raise the pressure to 14 MPa, keep the pressure unchanged, hot press for 5 minutes, and then discharge the material.

[0042] Verified according to the B.4.1 normal temperature torsion test and B.4.2 - 25 °C low temperature torsion test in GB / T 33606 - 2017, after 10000 times of 1080° torsion test in both positive and negative directions at normal temperature and 5000 times of 1080° torsion test in both positive and negative directions at low temperature, the appearance of the cable is intact. After torsion, a voltage of AC 50HZ 73.5KV is applied for 60 minutes of voltage withstand test, and no breakdown phenomenon occurs. Example 2

[0043] It is basically the same as Example 1, except that, by weight, the outer sheath layer is prepared from the following raw materials:

[0044] 100 parts of polyvinyl chloride, 10 parts of liquid terminal amino nitrile rubber, 10 parts of star - comb - shaped polybutadiene - g - polymethyl methacrylate copolymer, 20 parts of silicon dioxide nanotubes, 5 parts of composite lead stabilizer, 10 parts of carbon black, 1 part of paraffin, 2 parts of stearic acid, 3 parts of phosphate - based flame retardant, 0.5 part of antioxidant, 30 parts of plasticizer.

[0045] Verified according to the B.4.1 normal temperature torsion test and B.4.2 - 25 °C low temperature torsion test in GB / T 33606 - 2017, after 10000 times of 1080° torsion test in both positive and negative directions at normal temperature and 5000 times of 1080° torsion test in both positive and negative directions at low temperature, the appearance of the cable is intact. After torsion, a voltage of AC 50HZ 73.5KV is applied for 60 minutes of voltage withstand test, and no breakdown phenomenon occurs. Example 3

[0046] It is basically the same as Example 1, except that, by weight, the outer sheath layer is prepared from the following raw materials:

[0047] 90 parts of polyvinyl chloride, 5 parts of liquid terminal amino nitrile rubber, 5 parts of star - comb - shaped polybutadiene - g - polymethyl methacrylate copolymer, 10 parts of silicon dioxide nanotubes, 3 parts of composite lead stabilizer, 5 parts of carbon black, 0.1 part of paraffin, 1 part of stearic acid, 1 part of phosphate - based flame retardant, 0.1 part of antioxidant, 20 parts of plasticizer.

[0048] Verified by the normal temperature torsion test in B.4.1 and the -25°C low temperature torsion test in B.4.2 of GB / T 33606-2017, after 10,000 times of 1080° forward and reverse torsion tests at normal temperature and 5,000 times of 1080° forward and reverse torsion tests at low temperature, the appearance of the cable is intact. After torsion, a voltage of AC 50HZ 73.5KV is applied for 60 minutes of withstand voltage test, and no breakdown phenomenon occurs. Example 4

[0049] Basically the same as Example 1, the difference is that, by weight, the outer sheath layer is prepared from the following raw materials:

[0050] 100 parts of polyvinyl chloride, 5 parts of liquid terminal amino nitrile rubber, 10 parts of star-shaped comb-shaped polybutadiene-g-polymethyl methacrylate copolymer, 10 parts of silicon dioxide nanotubes, 5 parts of composite lead stabilizer, 5 parts of carbon black, 1 part of paraffin, 1 part of stearic acid, 3 parts of phosphate ester flame retardant, 0.1 part of antioxidant, 30 parts of plasticizer.

[0051] Verified by the normal temperature torsion test in B.4.1 and the -25°C low temperature torsion test in B.4.2 of GB / T 33606-2017, after 10,000 times of 1080° forward and reverse torsion tests at normal temperature and 5,000 times of 1080° forward and reverse torsion tests at low temperature, the appearance of the cable is intact. After torsion, a voltage of AC 50HZ 73.5KV is applied for 60 minutes of withstand voltage test, and no breakdown phenomenon occurs. Example 5

[0052] Basically the same as Example 1, the difference is that, by weight, the outer sheath layer is prepared from the following raw materials:

[0053] 90 parts of polyvinyl chloride, 10 parts of liquid terminal amino nitrile rubber, 5 parts of star-shaped comb-shaped polybutadiene-g-polymethyl methacrylate copolymer, 20 parts of silicon dioxide nanotubes, 3 parts of composite lead stabilizer, 10 parts of carbon black, 0.1 part of paraffin, 2 parts of stearic acid, 1 part of phosphate ester flame retardant, 0.5 part of antioxidant, 20 parts of plasticizer.

[0054] Verified by the normal temperature torsion test in B.4.1 and the -25°C low temperature torsion test in B.4.2 of GB / T 33606-2017, after 10,000 times of 1080° forward and reverse torsion tests at normal temperature and 5,000 times of 1080° forward and reverse torsion tests at low temperature, the appearance of the cable is intact. After torsion, a voltage of AC 50HZ 73.5KV is applied for 60 minutes of withstand voltage test, and no breakdown phenomenon occurs.

[0055] Comparative Example 1:

[0056] Basically the same as Example 1, the difference is that liquid terminal amino nitrile rubber is not added.

[0057] Verified by the normal temperature torsion test in B.4.1 and the low temperature torsion test at -25°C in B.4.2 of GB / T 33606-2017, after 10,000 times of 1080° forward and reverse torsion tests at normal temperature and 5,000 times of 1080° forward and reverse torsion tests at low temperature, the outer sheath layer of the cable cracked. After applying a voltage of AC 50HZ 73.5KV for 60 minutes of withstand voltage, breakdown phenomena occurred in all cases.

[0058] Comparative Example 2:

[0059] It is basically the same as Example 1, except that ordinary nitrile rubber is used instead of liquid terminal amino nitrile rubber.

[0060] Verified by the normal temperature torsion test in B.4.1 and the low temperature torsion test at -25°C in B.4.2 of GB / T 33606-2017, after 10,000 times of 1080° forward and reverse torsion tests at normal temperature and 5,000 times of 1080° forward and reverse torsion tests at low temperature, the appearance of the cable was intact. After applying a voltage of AC 50HZ 73.5KV for 60 minutes of withstand voltage, breakdown phenomena occurred in all cases.

[0061] Comparative Example 3:

[0062] It is basically the same as Example 1, except that star-shaped comb-shaped polybutadiene-g-polymethyl methacrylate copolymer is not added.

[0063] Verified by the normal temperature torsion test in B.4.1 and the low temperature torsion test at -25°C in B.4.2 of GB / T 33606-2017, after 10,000 times of 1080° forward and reverse torsion tests at normal temperature and 5,000 times of 1080° forward and reverse torsion tests at low temperature, the outer sheath layer of the cable cracked. After applying a voltage of AC 50HZ 73.5KV for 60 minutes of withstand voltage, breakdown phenomena occurred in all cases.

[0064] Comparative Example 4:

[0065] It is basically the same as Example 1, except that silicon dioxide nanotubes are not added.

[0066] Verified by the normal temperature torsion test in B.4.1 and the low temperature torsion test at -25°C in B.4.2 of GB / T 33606-2017, after 10,000 times of 1080° forward and reverse torsion tests at normal temperature and 5,000 times of 1080° forward and reverse torsion tests at low temperature, the appearance of the cable was intact. After applying a voltage of AC 50HZ 73.5KV for 60 minutes of withstand voltage, breakdown phenomena occurred in all cases.

[0067] Performance detection:

[0068] The outer sheath layers prepared in Examples 1-5 and Comparative Examples 1-4 were made into test pieces;

[0069] The tensile strength and elongation at break were tested in accordance with GB / T 1040.3-2006. The test specimens were dumbbell-shaped specimens with dimensions of 50 mm × 4 mm, and the tensile speed was 250 mm / min.

[0070] The test results are shown in Table 1 below:

[0071]

[0072] As can be seen from Table 1 above, the outer sheath layer prepared by the present invention has excellent tensile properties and can significantly improve the anti-torsion performance of the cable; from the comparison between Example 1 and Comparative Example 1, it can be seen that the addition of liquid terminal amino nitrile rubber plays a positive role in improving the tensile properties of the outer sheath layer; from the comparison between Example 1 and Comparative Example 2, it can be seen that the liquid terminal amino nitrile rubber has a better effect on improving the tensile properties of the outer sheath layer than ordinary nitrile rubber; from the comparison between Example 1 and Comparative Examples 3 and 4, it can be seen that the addition of star-shaped comb-like polybutadiene-g-polymethyl methacrylate copolymer and silicon dioxide nanotubes both play a positive role in improving the tensile properties of the outer sheath layer.

[0073] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A 35kV torsion-resistant cable for a wind turbine, characterized in that: It consists of a cable core and a ground wire, wherein the cable core and the ground wire are fixed by being covered by a torsion-resistant reinforcement layer and an outer sheath layer; The outer sheath layer is prepared from the following raw materials in parts by weight: 90-100 parts of polyvinyl chloride, 5-10 parts of liquid amino-terminated nitrile rubber, 5-10 parts of star-shaped comb-shaped polybutadiene-g-polymethyl methacrylate copolymer, 10-20 parts of silica nanotubes, 3-5 parts of composite lead stabilizer, 5-10 parts of carbon black, 0.1-1 parts of paraffin, 1-2 parts of stearic acid, 1-3 parts of phosphate flame retardant, 0.1-0.5 parts of antioxidant, and 20-40 parts of plasticizer; The preparation method of the star-shaped comb-shaped polybutadiene-g-polymethyl methacrylate copolymer is as follows: The star-shaped polybutadiene is synthesized by a formic acid-hydrogen peroxide in-situ method to obtain a star-shaped epoxidized polybutadiene, the star-shaped epoxidized polybutadiene is then subjected to an incomplete esterification reaction with 2-bromoisobutyryl bromide under the action of water to obtain a star-shaped brominated polybutadiene, and the star-shaped brominated polybutadiene is used as an initiator, cuprous chloride and cupric chloride are used as a catalyst and a regulator, respectively, and N,N,N',N'',N''-pentamethyldiethylenetriamine is used as a ligand to initiate polymerization of methyl methacrylate by an ATRP method to finally obtain the star-shaped comb-shaped polybutadiene-g-polymethyl methacrylate copolymer; The molar ratio of epoxy group to 2-bromoisobutyryl bromide in the star-shaped epoxidized polybutadiene is 1:0.1-0.8; The molar ratio of bromine atoms in the star-shaped brominated polybutadiene to methyl methacrylate is 1:10-40; The preparation method of silica nanotubes is as follows: The sepiolite is crushed and washed with deionized water, first added to a hydrochloric acid solution to remove impurities, the reaction solution is filtered, the solid is collected and washed thoroughly with deionized water, then added to a polyvinyl pyrrolidone solution, ultrasonically treated, and then sodium borohydride is added. The reaction solution is reacted at 50-70°C for 1-5h, and finally the product is collected, washed thoroughly with deionized water, and then dried.

2. The 35kV torsion-resistant cable for wind turbine generator according to claim 1, characterized in that: The cable core comprises a conductor, a conductor shielding layer, an EPR insulating layer and an insulating shielding layer from inside to outside.

3. The 35kV torsion-resistant cable for wind turbine generator according to claim 1, characterized in that: The torsion-resistant reinforcement layer is woven from Kevlar fibers.

4. The 35kV torsion-resistant cable for wind turbine generator according to claim 1, characterized in that: The phosphate flame retardant is any one or more combinations of tris(isopropylphenyl) phosphate, tris(2-chloroethyl) phosphate, and tris(2-chloropropyl) phosphate.

5. The 35kV torsion-resistant cable for wind turbine generator according to claim 1, characterized in that: The antioxidant is any one or more combinations of antioxidant 1010, antioxidant 1076, antioxidant 245, and antioxidant 168.

6. The 35kV torsion-resistant cable for wind turbine generator according to claim 1, characterized in that: The plasticizer is any one or more combinations of dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, dioctyl phthalate, butyl benzyl phthalate, and diisononyl phthalate.

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