A high-temperature superconducting triaxial cable

Abstract

This invention discloses a high-temperature superconducting three-phase coaxial cable, belonging to the field of superconducting electrical technology. The cable includes fixing screws and clips, a liquid nitrogen channel, an insulation layer, an inner skeleton, three-phase superconducting cables, and an outer skeleton. The fixing screws and clips are uniformly arranged along the cable axis to radially fix and axially limit the liquid nitrogen channel and insulation layer; the insulation layer provides electrical isolation between the cooling channel and the outer current-carrying structure; the inner skeleton has symmetrically divided channels along its circumference, with the three-phase superconducting cables embedded in corresponding channels, arranged symmetrically at 120° intervals, utilizing a quasi-isotropic structure to reduce magnetic field coupling and AC loss; the outer skeleton covers the outside of the copper skeleton. This invention solves the problems of poor structural stability and high AC loss in existing superconducting cables, achieving a compact structure, high current-carrying capacity, and stable operation for power transmission, suitable for high-power, compact AC / DC superconducting power transmission scenarios.

Description

Technical Field

[0001] This invention belongs to the field of superconducting electrical technology, specifically relating to a high-temperature superconducting three-phase coaxial cable, which is suitable for high-power, compact three-phase AC superconducting power transmission scenarios, while also meeting the requirements for low-loss DC high-current transmission. Background Technology

[0002] With the continuous expansion of power system capacity, traditional transmission cables face problems such as high loss, limited current carrying capacity, and large footprint. High-temperature superconducting cables, with their advantages of low loss, high current, and compact size, have become one of the key technologies for solving these problems. The mature application of second-generation REBCO high-temperature superconducting tape has further promoted the engineering development of superconducting cables. However, existing triaxial superconducting cables still have many shortcomings: low integration of cooling channels and conductor structure, resulting in poor cold energy transfer efficiency; insufficient phase positioning accuracy, strong magnetic field coupling leading to large AC losses; lack of reliable internal structure fixation, making them prone to displacement and wear under thermal expansion and contraction and electromagnetic forces; and unreasonable fixing methods for insulation layers and cooling channels, affecting long-term operational stability. To solve these problems, it is urgent to design a compact, highly efficient, precisely positioned, and reliably fixed triaxial superconducting cable. By optimizing the structural design and assembly method of each functional layer, the current carrying capacity, operational stability, and economy of the superconducting cable can be improved, promoting the large-scale application of superconducting power transmission technology. Summary of the Invention

[0003] The purpose of this invention is to provide a high-temperature superconducting triaxial cable to solve the problems of low cooling efficiency, strong interphase coupling, and poor structural stability of existing triaxial superconducting cables.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A high-temperature superconducting three-phase coaxial cable is disclosed. The high-temperature superconductor includes: fixing screws and clips, liquid nitrogen channels, insulation layers, inner skeleton, ABC three-phase superconducting cables, and outer skeleton. The components work together to achieve efficient cooling, reliable insulation, precise positioning, and stable power transmission. The ABC three-phase superconducting cable includes superconducting strands and flexible insulating metal materials.

[0005] The fixing screws and latches are mechanical fixing components, including an annular latch body and evenly distributed fixing screws. The annular latch body is made of epoxy resin, and the fixing screws are made of copper alloy to avoid magnetic interference. The fixing screws and latches achieve radial fixing of liquid nitrogen passage and insulation, and at the same time prevent relative displacement of each layer structure through axial limiting, ensuring the stability of the overall cable structure.

[0006] The liquid nitrogen channel is the core of the cooling medium flow. It is made of oxygen-free copper seamless tube. Oxygen-free copper has both excellent thermal conductivity and structural strength. The inner wall is polished to reduce the flow resistance of liquid nitrogen. 77K liquid nitrogen flows in the channel and uses forced convection to ensure that the cooling capacity is quickly transferred to each phase of the superconducting cable and maintain the superconducting operating environment.

[0007] The insulation layer is an electrical isolation component, made of polyimide film or epoxy resin composite material. This layer continuously and seamlessly covers the outside of the liquid nitrogen channel along the cable axis, achieving electrical isolation between the liquid nitrogen channel and the outer skeleton and superconducting cable. It also has low temperature resistance and high flexibility, which can adapt to the deformation requirements of cable thermal expansion and contraction, and avoid brittle breakage in low temperature environment.

[0008] The inner skeleton serves as a support and heat-conducting component. It is integrally formed from a high thermal conductivity copper alloy and is symmetrically distributed in three equal parts along the circumference to form three independent rectangular channels. The cross-section of the channels matches the shape of the ABC three-phase superconducting cable to ensure a tight fit after the superconducting cable is embedded. The inner skeleton provides stable mechanical positioning for the superconducting cable and can quickly conduct the heat generated during the operation of the superconducting cable to the liquid nitrogen channel, forming an efficient thermal path of "superconducting cable - inner skeleton - liquid nitrogen channel".

[0009] The ABC three-phase superconducting cable is the core of power transmission. It is made of tightly stacked second-generation REBCO high-temperature superconducting tapes. Each cable has a rectangular cross-section and is made of standard REBCO tapes stacked together. Gaps are reserved between the tapes and filled with flexible insulation material to balance current distribution and thermal expansion and contraction. Each phase of the superconducting cable is covered with a thin polyimide insulation layer. After the three phases are embedded in the corresponding channels of the copper skeleton, they are symmetrically distributed at a 120° angle along the circumference. The quasi-isotropic structure reduces the magnetic field coupling between phases, improves current balance, and reduces AC loss. The three-phase superconducting cables are connected in parallel. The current amplitude of each phase is equal and the phases differ by 120°. Different current carrying requirements can be adapted by adjusting the number of tapes stacked.

[0010] The outer skeleton is an integral protective component, made of aluminum alloy or copper alloy in a cylindrical structure, which has the advantages of both lightweight and mechanical strength. The outer skeleton covers the insulation layer and the outside of the ABC three-phase superconducting cable, and is closely attached to the insulation layer to form a continuous mechanical support and heat conduction path. This not only prevents radial displacement of the cable during transportation, laying and operation, and suppresses micro-vibrations caused by electromagnetic force, but also helps to dissipate radial heat, further improving the overall heat dissipation efficiency. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained according to the drawings provided by the present invention without creative effort.

[0012] Figure 1 This is a schematic diagram of the structure of the high-temperature superconducting triaxial cable provided by the present invention.

[0013] Figure 2 This is a schematic diagram of the fixing screws and bayonet structure of the high-temperature superconducting triaxial cable provided by the present invention.

[0014] Figure 3 This is a schematic diagram of the liquid nitrogen channel structure of the high-temperature superconducting triaxial cable provided by the present invention.

[0015] Figure 4 This is a schematic diagram of the insulation layer structure of the high-temperature superconducting triaxial cable provided by the present invention.

[0016] Figure 5 This is a schematic diagram of the inner skeleton structure of the high-temperature superconducting triaxial cable provided by the present invention.

[0017] Figure 6 A schematic diagram of the ABC three-phase superconducting cable body of the high-temperature superconducting three-phase coaxial cable provided by the present invention.

[0018] Figure 7 This is a schematic diagram of the outer skeleton structure of the high-temperature superconducting triaxial cable provided by the present invention. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The purpose of this invention is to provide a high-temperature superconducting three-phase coaxial cable to meet the requirements of high-power, compact three-phase AC superconducting power transmission scenarios, while also meeting the requirements of high-current, low-loss DC transmission.

[0021] Figure 1 This is a schematic diagram of the structure of a high-temperature superconducting three-phase coaxial cable provided by the present invention. The overall structure, from the inside out, consists of: ① fixing screws and clips, ② liquid nitrogen channel, ③ insulation layer, ④ inner skeleton, ⑤ ABC three-phase superconducting cable, and ⑥ outer skeleton. Please refer to [link / reference]. Figure 1 ,2 3, 4, the ② liquid nitrogen channel is in the shape of a three-phase spiral, the ③ inner layer of the insulation layer is in the shape of a spiral, and the outer layer is in the shape of a cylinder. The ① fixing screws and buckles fix the ② liquid nitrogen channel and the ③ insulation layer radially and limit their axial movement. A set of screws is set at intervals along the cable axis and is fitted on the inner side of the ② liquid nitrogen channel and the ③ insulation layer. The positioning is achieved by radially tightening the screws.

[0022] like Figure 3 , 4 As shown, liquid nitrogen flows through the ② liquid nitrogen channel as a cooling medium, providing a stable low-temperature environment for the entire cable and ensuring that the ⑤ABC three-phase superconducting cable operates below the superconducting critical temperature. The ② liquid nitrogen channel also serves as the central support reference for the ④ inner layer skeleton, ensuring the overall structure is coaxially arranged. The ③ insulating layer tightly covers the space between the ② liquid nitrogen channel and the ④ inner layer skeleton, and is made of polyimide, epoxy resin, polypropylene composite fiber paper, or low-temperature insulating film, achieving electrical isolation between the liquid nitrogen channel, the inner layer skeleton, and the superconducting conductor.

[0023] like Figure 1 , 2 As shown in Figures 3, 4, and 5, the ③ insulating layer and the ② liquid nitrogen channel wrap around the inner skeleton. After the insulating layer and the ② liquid nitrogen channel are fixed by the ① fixing screws and clips, the ④ inner skeleton is the core support base of the cable, which has sufficient mechanical strength and thermal conductivity. The ④ inner skeleton has three symmetrical channels evenly opened along the circumference, which are used to embed the A-phase, B-phase, and C-phase superconducting cables respectively. The channel shape matches the shape of the ⑤ ABC three-phase superconducting cable. It is placed in the middle of the ③ insulating layer and the ② liquid nitrogen channel and is tightly wrapped.

[0024] like Figure 1 , 4 As shown in Figures 5 and 6, the three-phase superconducting cable ⑤ABC serves as the current-carrying core of the cable, embedded in three corresponding channels of the inner skeleton ④, symmetrically distributed along the circumference at 120° intervals, forming a three-phase coaxial structure. Each phase of the superconducting cable is formed by stacking and twisting second-generation REBCO high-temperature superconducting tapes to constitute quasi-isotropic superconducting strands. The strands are wrapped with flexible insulating metal material or a thin insulating layer to achieve phase-to-phase insulation and mechanical protection. The current amplitude of each phase of the three-phase cable is equal, and the phases differ by 120° sequentially. During balanced operation, it has good external magnetic field cancellation effect and low AC loss, making it suitable for both power frequency AC and DC transmission scenarios.

[0025] like Figure 1 , 4As shown in Figures 7 and 8, the outer skeleton (⑥) is a cylindrical integral sheath that covers the outermost part of the inner skeleton (④) and the three-phase superconducting cable (⑤ABC). It is made of copper, aluminum alloy, or stainless steel. The outer skeleton (⑥) provides radial clamping, mechanical protection, vibration resistance, and compression resistance to all internal structures. At the same time, it further enhances the heat conduction path, assists in heat dissipation, and improves the overall structural rigidity of the cable, ensuring that the internal structure does not shift, wear, or deform during laying and operation.

[0026] In actual assembly and implementation, the present invention is assembled in a sequence from the inside out: 1) First, prepare ② the liquid nitrogen channel, clean and polish it to ensure a smooth flow path; 2) Evenly cover the outer wall of ② the liquid nitrogen channel with ③ the insulating layer, ensuring no gaps or wrinkles; 3) Install and pre-fix the ① fixing screws and clips at the set intervals to ensure coaxiality; 4) Coaxially insert ④ the inner skeleton, tightly fitting it with the insulating layer ③; 5) Embed ⑤ the three-phase superconducting cables ABC into the corresponding slots of the inner skeleton ④, adjusting the symmetry and tightness; 6) Finally, completely cover and fix ⑥ the outer skeleton to form a complete and compact three-phase coaxial superconducting cable. In this embodiment, the size, material, and quantity of superconducting tape of each component can be flexibly adjusted according to the current carrying capacity, voltage level, and cooling conditions. Without changing the overall structural form, high-power compact superconducting power transmission with different capacities and voltage levels can be achieved.

Claims

1. A high-temperature superconducting triaxial cable, characterized in that, From the inside out, it includes: a liquid nitrogen channel, an insulating layer, an inner skeleton, ABC three-phase superconducting cables, and a metal skeleton. The liquid nitrogen channel is provided with fixing screws and clips on its inner side. The fixing screws and clips are used to radially fix the liquid nitrogen channel and the insulating layer and to limit their axial movement. The inner skeleton has three symmetrically distributed channels along the circumference, and the ABC three-phase superconducting cables are respectively embedded in the corresponding channels. The outer skeleton covers the copper skeleton to form an overall protective structure.

2. The high-temperature superconducting triaxial cable according to claim 1, characterized in that, The fixing screws and buckles include an annular buckle body and evenly distributed fixing screws. The annular buckle body is sleeved on the inner side of the insulating layer, and the fixing screws are arranged radially along the annular buckle body to achieve fixation by pressing against the outer wall of the liquid nitrogen channel.

3. The high-temperature superconducting triaxial cable according to claim 1, characterized in that, The liquid nitrogen channel is an oxygen-free copper spiral arc structure with a polished inner wall.

4. The high-temperature superconducting triaxial cable according to claim 1, characterized in that, The insulation layer is a polyimide film or an epoxy resin composite material, which is continuously wrapped around the outside of the liquid nitrogen channel along the cable axis.

5. A high-temperature superconducting triaxial cable according to claim 1, characterized in that, The inner skeleton is a one-piece molded structure, and the channel cross-section is a rectangle that matches the ABC three-phase superconducting cable.

6. A high-temperature superconducting triaxial cable according to claim 1, characterized in that, The ABC three-phase superconducting cable is made of second-generation REBCO superconducting tape stacked together. The three phases are symmetrically distributed at 120° along the circumference. The cable is made of multiple superconducting strands stacked together, and the outer layer is wrapped in a rectangle by flexible insulating material.

7. A high-temperature superconducting triaxial cable according to claim 1, characterized in that, The inner skeleton is an aluminum alloy or copper alloy cylindrical structure that is tightly fitted to the insulation layer.

8. A high-temperature superconducting triaxial cable according to claim 2, characterized in that, The fixing screws and clips are evenly distributed along the cable axis and are symmetrically distributed at 120° on the same radial direction.

9. A high-temperature superconducting triaxial cable according to claim 1, characterized in that, The ABC three-phase superconducting cable is covered with a thin layer of polyimide insulation.

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