A medium-voltage cable with fiber optic composite carbon fiber core for high-altitude wind power

Abstract

This invention relates to the field of medium-voltage cable technology, specifically a fiber-optic composite carbon fiber core medium-voltage cable for high-altitude wind power. From the inside out, it comprises a fiber-optic composite carbon fiber core rod, an aluminum profile conductor layer, a PI film sintered layer, and an overhead insulation layer, with each layer coaxially arranged and tightly bonded. The fiber-optic composite carbon fiber core rod, as the core load-bearing component, consists of carbon fiber bundles, tightly wrapped optical fibers, and a cladding layer. The aluminum profile conductor layer is made of stranded aluminum profile monofilaments. The PI film sintered layer is formed by wrapping and sintering PI tape. The overhead insulation layer is extruded onto the outside of the PI film sintered layer. This invention achieves high strength load-bearing capacity, long length and lightweight design, real-time monitoring, and high insulation and weather resistance, making it suitable for high-altitude wind power medium-voltage transmission scenarios.

Description

Technical Field

[0001] This invention relates to the field of medium-voltage cable technology, specifically to a medium-voltage cable with fiber optic composite carbon fiber core for high-altitude wind power, suitable for medium-voltage power transmission between high-altitude wind power platforms and ground power grids, and can also realize real-time acquisition and transmission of airship operating condition data information, adaptable to harsh operating environments such as high-altitude strong winds, alternating high and low temperatures, and strong ultraviolet radiation. Background Technology

[0002] High-altitude wind power, as a new type of clean energy generation technology, typically deploys its power generation platforms in high-altitude, windy areas. The cables must be suspended at high altitudes, facing large spans and high load-bearing requirements, in addition to long-term corrosion from strong winds, temperature differences, ultraviolet radiation, and salt spray, making the operating conditions extremely harsh. Currently, the industry mostly uses copper-core medium-voltage rubber-sheathed cables, but their performance in practical applications is not ideal. Traditional copper-core torsion-resistant cables are heavy, and their load-bearing capacity relies primarily on the copper conductor itself, making long-length production difficult and requiring additional load-bearing structures during installation. To ensure insulation performance, the rubber sheath insulation layer is thicker, further increasing the cable's outer diameter and weight, making long-distance high-altitude suspension increasingly difficult. Existing fiber optic composite cables are mostly designed for ground-based power grids or conventional wind power scenarios, lacking targeted optimization for the special requirements of high-altitude strong winds, medium-voltage transmission, and long-term weather resistance, making it difficult to guarantee system operational stability. Summary of the Invention

[0003] The technical problem to be solved by this invention is that existing high-altitude wind power cables have insufficient load-bearing capacity, cannot be produced in large lengths, cannot be monitored in real time, and have poor structural stability, thus failing to meet the requirements for long-term stable operation of high-altitude wind power.

[0004] The technical solution adopted by this invention to solve its technical problem is: a medium-voltage cable with optical fiber composite carbon fiber core for high-altitude wind power, comprising, from the inside out, an optical fiber composite carbon fiber core rod, an aluminum profile conductor layer, a PI film sintered layer, and an overhead insulation layer, with each layer coaxially arranged and tightly bonded; the optical fiber composite carbon fiber core rod serves as the core load-bearing component, the aluminum profile conductor layer is made of aluminum profile single filaments twisted together, the PI film sintered layer is made of two layers of 0.05mm PI tape wrapped and sintered, and the overhead insulation layer is extruded on the outside of the PI film sintered layer with a thickness of 1.5mm.

[0005] Furthermore, the fiber composite carbon fiber core rod consists of carbon fiber bundles, tightly packed optical fibers, and a cladding layer; the carbon fiber bundles are made of multiple strands of prepreg yarn twisted together, with a twisting pitch of 50mm~80mm; there are 2~4 tightly packed optical fibers, symmetrically embedded inside the carbon fiber bundles; the cladding layer is a modified epoxy resin with a thickness of 0.8mm~1.2mm.

[0006] Furthermore, the carbon fiber bundle is made of 19 or 37 strands of prepreg yarn twisted together, and the core rod diameter after twisting is 6mm~10mm, with a tensile strength ≥2800MPa and an elongation at break ≥1.8%; the outer side of the tightly packed optical fiber is wrapped with a polytetrafluoroethylene buffer layer with a thickness of 0.2mm~0.3mm.

[0007] Furthermore, the aluminum profile conductor layer uses 6061 aluminum alloy aluminum profile monofilaments, which, after aging heat treatment, have a tensile strength ≥220MPa and a conductivity ≥61%IACS. The aluminum profile monofilaments have a fan-shaped or tile-shaped cross section and are concentrically stranded. The stranding pitch is 12 to 16 times the diameter of the aluminum profile monofilament. During stranding, pre-deformation and compaction treatment are performed, and the filling factor is ≥90%.

[0008] Furthermore, the aluminum profile has 19 to 61 single wires, and the cross-sectional area of ​​each single wire is 2 mm² to 5 mm².

[0009] Furthermore, the PI tape of the PI film sintering layer is a modified polysiloxane-polyimide composite film with a wrapping angle of 45°, an overlap rate of 30%~50%, a sintering temperature of 750℃~850℃, a sintering time of 3min~5min, and a total thickness of 0.10mm, which is firmly bonded to the surface of the aluminum profile conductor layer.

[0010] Furthermore, the overhead insulation layer uses modified cross-linked polyethylene material, with the addition of nano-level inorganic fillers, antioxidants and light stabilizers. The dielectric strength is ≥25kV / mm, the high and low temperature resistance range is -40℃~80℃, the concentricity during extrusion is ≤5%, and the wall thickness deviation is ≤±0.1mm.

[0011] Furthermore, the cable can withstand 35kV medium-voltage transmission, is suitable for suspension requirements at heights of 4000m or more, and has a service life of ≥30 years.

[0012] The beneficial effects of this invention are as follows: The fiber-optic composite carbon fiber core rod, as the core load-bearing component, reduces weight by more than 40% compared to traditional steel cores, increases tensile strength by 2-3 times, and reduces the coefficient of linear expansion by more than 60%, meeting the requirements for long-length suspensions exceeding 2000m. Combined with the excellent corrosion resistance and fatigue resistance of carbon fiber materials, it can operate continuously for more than 30 years in high-altitude strong winds and ultraviolet environments, significantly reducing maintenance frequency. The aluminum profile conductor layer uses fan-shaped or tile-shaped monofilament stranding with a fill factor exceeding 90%, reducing conductive loss by 15%-2% compared to round stranded conductors. The high-strength aluminum alloy material, with a 5% strength, balances conductivity and mechanical strength, making it resistant to loosening and wear under strong winds at high altitudes. The PI film sintered layer and the overhead insulation layer form a double protection, with the sintered layer providing high-temperature resistant sealing and isolation. The modified overhead insulation layer has a dielectric strength of no less than 25kV / mm, maintaining stability in high UV, large temperature difference, and salt spray environments. Meanwhile, the tightly packed optical fiber embedded with a carbon fiber core rod provides real-time feedback on cable temperature and stress changes based on the Brillouin scattering principle, enabling early warning for safety. Overall, this ensures the reliability and safety of high-altitude wind power transmission. Attached Figure Description

[0013] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0014] Figure 1 This is a schematic diagram of the cross-sectional structure of the optical fiber composite carbon fiber core medium-voltage cable for high-altitude wind power according to the present invention.

[0015] Explanation of reference numerals in the attached figures: 1. Fiber composite carbon fiber core rod; 11. Carbon fiber bundle; 12. Tightly packed fiber; 13. Cladding layer; 2. Aluminum profile conductor layer; 3. PI thin film sintered layer; 4. Overhead insulation layer. Detailed Implementation

[0016] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0017] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connection" and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0018] Figure 1 The high-altitude wind power fiber composite carbon fiber core medium voltage cable shown includes, from the inside out, a fiber composite carbon fiber core rod 1, an aluminum wire conductor layer 2, a PI film sintered layer 3, and an overhead insulation layer 4. Each layer is coaxially arranged and tightly bonded, with a coaxiality error ≤0.1mm.

[0019] The fiber-optic composite carbon fiber core rod 1, as the core load-bearing component of the cable, is coaxially positioned at the center of the cable and consists of a carbon fiber bundle 11, a tight-buffered optical fiber 12, and a cladding layer 13. The carbon fiber bundle 11 is made of multiple strands of high-strength pre-impregnated carbon fiber yarn twisted together, with a twist pitch controlled between 50mm and 80mm to ensure the core rod's tensile strength and flexibility, adapting to high-altitude strong wind loads and large-span suspension requirements. The tight-buffered optical fiber 12 is embedded inside the carbon fiber bundle 11, using 2 to 4 tightly-buffered optical fibers symmetrically distributed. The optical fibers are selected as single-mode or multi-mode fibers. Based on the Brillouin scattering time-domain reflectometry principle, it can realize real-time monitoring of cable operating parameters such as temperature and stress, providing data support for safety early warning. The cladding layer 13, made of modified epoxy resin, is wrapped around the carbon fiber bundle 11 and the tight-buffered optical fiber 12, with a thickness of 0.8mm to 1.2mm. It serves to fix, insulate, and buffer, preventing the optical fiber from being worn by the carbon fiber bundle, while also improving the bonding force between the core rod and the outer conductor.

[0020] The carbon fiber bundle 11 is preferably made of 19 or 37 strands of pre-impregnated carbon fiber yarn twisted together. After twisting, the core rod diameter is 6mm~10mm, the tensile strength is ≥2800MPa, and the elongation at break is ≥1.8%, ensuring that the core rod has sufficient load-bearing capacity to meet the requirements of high-altitude, large-span suspension. The tightly wrapped optical fiber 12 is preferably wrapped with a polytetrafluoroethylene buffer layer with a thickness of 0.2mm~0.3mm to further protect the optical fiber and prevent it from being damaged by core rod twisting, cable bending, or high-altitude vibration, thus ensuring the stability of the monitoring signal.

[0021] The aluminum profile conductor layer 2 is wrapped around the outer side of the fiber composite carbon fiber core rod 1 and is composed of several aluminum profile monofilaments twisted together. The aluminum profile monofilaments are made of 6061 aluminum alloy, and after aging heat treatment, they have a tensile strength ≥220MPa and a conductivity ≥61%IACS, balancing high strength and high conductivity. The aluminum profile monofilaments have a fan-shaped or tile-shaped cross-section and are twisted concentrically. The twisting pitch is 12 to 16 times the diameter of the aluminum profile monofilament. Constant tension control is used during twisting, and each aluminum profile monofilament is pre-deformed. After twisting, a compaction treatment is performed to ensure that the conductor layer fill factor is ≥90%, the surface is smooth and burr-free, reducing conductive loss, and improving the structural stability of the conductor layer, avoiding the loosening and wear of monofilaments caused by strong wind vibrations at high altitudes. The aluminum profile wire is preferably made of 19 to 61 single wires, with a single wire cross-sectional area of ​​2 mm² to 5 mm², and the outer diameter of the stranded conductor layer is 15 mm to 25 mm. The conductor DC resistance is ≤0.1 Ω / km (20℃), which meets the requirements of medium voltage and high current transmission in high-altitude wind power.

[0022] The PI film sintered layer 3 is wrapped around the outer side of the aluminum profile conductor layer 2. It is formed by wrapping and sintering two 0.05mm thick polyimide films, with a total thickness of 0.10mm. The PI film is preferably a modified polysiloxane-polyimide composite film, which has a much lower resistance to atomic oxygen erosion than ordinary PI film and extends its high and low temperature resistance range to -60℃ to 200℃, further improving the high temperature resistance, weather resistance, and service life of the sintered layer. During the wrapping of the PI film, the wrapping angle is controlled at 45°, and the overlap rate is 30% to 50%. After wrapping, it is placed in a sintering furnace for high-temperature sintering at 750℃ to 850℃ for 3 to 5 minutes. Through sintering, the two PI film layers are tightly bonded and firmly adhered to the surface of the aluminum profile conductor layer 2, expelling interlayer air and forming a sealed isolation barrier. The sintered layer can serve as insulation, high temperature resistance, and corrosion protection, while also buffering the stress between the outer insulation layer and the conductor layer, preventing the insulation layer from peeling off from the conductor layer due to thermal expansion and contraction, and making it suitable for high-altitude and high-low temperature alternating environments.

[0023] The overhead insulation layer 4 is extruded onto the outside of the PI film sintered layer 3, with a thickness of 1.5mm. It is made of modified cross-linked polyethylene material with high insulation performance and high weather resistance. The material's weather resistance, high and low temperature resistance, and insulation performance are improved through synergistic modification with nano-scale inorganic fillers (alumina and silane coupling agents modified silica) and special antioxidants and light stabilizers. The extrusion process employs three-layer co-extrusion online monitoring technology to ensure that the concentricity of the insulation layer is ≤5%, the wall thickness deviation is ≤±0.1mm, and the surface is smooth without bubbles or cracks. This insulation layer can withstand 35kV medium-voltage transmission requirements, has a dielectric strength ≥25kV / mm, and can operate stably for a long time within the range of -40℃ to 80℃. It is resistant to ultraviolet radiation, salt spray, and sand and dust erosion, effectively preventing medium-voltage leakage and insulation aging, and ensuring the safety of medium-voltage transmission.

[0024] An additional bird-proof sheath can be added to the surface of the overhead insulation layer 4. The sheath thickness is 0.3mm~0.5mm. It uses modified materials with added repellent additives to reduce the risk of insulation damage caused by bird activity. At the same time, water-swellable water-blocking powder is added inside the insulation layer to form a radial water-blocking barrier to prevent moisture intrusion and improve the cable's moisture resistance.

[0025] The cable of this invention uses an optical fiber composite carbon fiber core rod 1 as the core load-bearing component. Compared with traditional steel cores, it is more than 40% lighter, has a 2-3 times higher tensile strength, and a more than 60% lower coefficient of linear expansion. It also offers superior self-supporting capacity when laid vertically, making it suitable for long-length suspension applications exceeding 2000m. The aluminum profile conductor layer 2 uses fan-shaped or tile-shaped aluminum profiles twisted into single strands with a fill factor ≥90%, reducing conductive loss by 15%-25% compared to traditional round stranded conductors. The PI film sintered layer 3 provides effective insulation, high-temperature resistance, and corrosion protection. The modified overhead insulation layer 4 significantly improves weather resistance, effectively resisting harsh high-altitude environments. The synergistic cooperation between these layers achieves high strength load-bearing capacity, high conductivity efficiency, high insulation and weather resistance, lightweight design for long lengths, and real-time monitoring capabilities, making it suitable for high-altitude wind power medium-voltage transmission scenarios.

[0026] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A medium-voltage cable with fiber optic composite carbon fiber core for high-altitude wind power, characterized in that: From the inside out, it includes an optical fiber composite carbon fiber core rod (1), an aluminum profile conductor layer (2), a PI film sintered layer (3), and an overhead insulation layer (4). Each layer is coaxially arranged and tightly bonded. The optical fiber composite carbon fiber core rod (1) serves as the core load-bearing component. The aluminum profile conductor layer (2) is made of aluminum profile single filaments twisted together. The PI film sintered layer (3) is made of two layers of 0.05mm PI tape wrapped and sintered. The overhead insulation layer (4) is extruded on the outside of the PI film sintered layer (3) and has a thickness of 1.5mm.

2. The optical fiber composite carbon fiber core medium-voltage cable for high-altitude wind power according to claim 1, characterized in that: The fiber composite carbon fiber core rod (1) is composed of carbon fiber bundle (11), tight-packed optical fiber (12) and cladding layer (13); the carbon fiber bundle (11) is made of multiple strands of pre-impregnated carbon fiber yarn twisted together, with a twisting pitch of 50mm~80mm; there are 2~4 tight-packed optical fibers (12), which are symmetrically embedded inside the carbon fiber bundle (11); the cladding layer (13) is modified epoxy resin with a thickness of 0.8mm~1.2mm.

3. A medium-voltage cable with fiber optic composite carbon fiber core for high-altitude wind power according to claim 2, characterized in that: The carbon fiber bundle (11) is made of 19 or 37 strands of carbon fiber prepreg yarn twisted together. The diameter of the core rod after twisting is 6mm~10mm, the tensile strength is ≥2800MPa, and the elongation at break is ≥1.8%. The tight-packed optical fiber (12) is wrapped with a polytetrafluoroethylene buffer layer with a thickness of 0.2mm~0.3mm.

4. A medium-voltage cable with fiber optic composite carbon fiber core for high-altitude wind power according to claim 1, characterized in that: The aluminum profile conductor layer (2) is made of 6061 aluminum alloy aluminum profile monofilament. After aging heat treatment, the tensile strength is ≥220MPa and the conductivity is ≥61%IACS. The aluminum profile monofilament has a fan-shaped or tile-shaped cross section and is concentrically stranded. The stranding pitch is 12 to 16 times the diameter of the aluminum profile monofilament. Pre-deformation and compaction treatment are carried out during stranding, and the filling coefficient is ≥90%.

5. A medium-voltage cable with fiber optic composite carbon fiber core for high-altitude wind power according to claim 4, characterized in that: The aluminum profile has 19 to 61 single wires, and the cross-sectional area of ​​each single wire is 2 mm² to 5 mm².

6. A medium-voltage cable with fiber optic composite carbon fiber core for high-altitude wind power according to claim 1, characterized in that: The PI tape of the PI film sintering layer (3) is a modified polysiloxane-polyimide composite film with a wrapping angle of 45°, an overlap rate of 30%~50%, a sintering temperature of 750℃~850℃, a sintering time of 3min~5min, and a total thickness of 0.10mm. It is firmly bonded to the surface of the aluminum wire conductor layer (2).

7. A medium-voltage cable with fiber optic composite carbon fiber core for high-altitude wind power according to claim 1, characterized in that: The overhead insulation layer (4) is made of modified cross-linked polyethylene material, with the addition of nano-level inorganic fillers, antioxidants and light stabilizers. The dielectric strength is ≥25kV / mm, the high and low temperature resistance range is -40℃~80℃, the concentricity during extrusion is ≤5%, and the wall thickness deviation is ≤±0.1mm.

8. A medium-voltage cable with optical fiber composite carbon fiber core for high-altitude wind power according to any one of claims 1 to 7, characterized in that: The cable can withstand 35kV medium voltage transmission, is suitable for suspension requirements at heights of 4000m and above, and has a service life of ≥30 years.

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