Superconducting direct current cable

Abstract

The invention relates to the technical field of cables, and discloses a superconducting direct-current cable which comprises a hollow framework, a plurality of superconductor layers and an external insulating layer which are sequentially arranged from inside to outside, the superconductor layers are arranged on the outer side of the hollow framework, the periphery of the hollow framework is sequentially wrapped with the multiple superconductor layers from inside to outside, and the external insulating layer is arranged on the outer side of the hollow framework. Each superconductor layer comprises a plurality of double-winding sub-cables which are spirally arranged in the same direction, each double-winding sub-cable comprises a positive pole belt, a negative pole belt and a sub-cable insulating layer, the sub-cable insulating layer wraps the peripheries of the positive pole belt and the negative pole belt, and the sub-cable insulating layer is used for providing an insulating environment for the positive pole belt and the negative pole belt; according to the invention, through the plurality of double-winding sub-cables which are spirally arranged in the same direction, the current-carrying capability is improved, the sub-cable insulating layer ensures electrical isolation, the double-winding sub-cables self-counteract a magnetic field structure to reduce self-field effect suppression, and the situation of non-uniform current distribution is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and particularly to a superconducting DC cable. Background Art

[0002] A superconducting DC cable is a power facility that uses high-temperature superconducting materials as conductors and is specifically used for transmitting direct current. Since the high-temperature superconducting material has almost zero resistance in the superconducting state, the superconducting DC cable can carry an extremely high current density and transmit a large amount of electric energy. In the superconducting state, the power transmission of the superconducting DC cable has almost no loss, which helps to improve the power transmission efficiency and reduce energy waste. Compared with conventional cables, the superconducting DC cable has a smaller size and lighter weight under the same transmission capacity, which helps to save the installation space and material cost. Due to technical advantages such as high current-carrying density, low loss, small electromagnetic pollution, small size and light weight under the same transmission capacity, the high-temperature superconducting cable has become a powerful tool for increasing the power transmission capacity of cities and solving the problem of tight land resources. These characteristics make the high-temperature superconducting cable have a wide application prospect in the renovation and new construction projects of urban power grids.

[0003] Currently, existing superconducting DC cables widely adopt a forming scheme in which multiple superconducting tapes are wound. However, this structure has the problem of uneven current distribution among multiple tapes. In practical applications, due to factors such as non-superconducting welding between superconducting tapes, non-superconducting connection between the superconductor and the terminal, and non-uniformity of the critical current and N value of superconducting tapes in different branches, the characteristics of each parallel superconducting tape are not exactly the same, resulting in uneven current distribution. This uneven current distribution will limit the current-carrying capacity of the superconducting DC cable, and thus affect the overall performance of the superconducting DC cable. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that in the prior art, when there are multiple tapes in a superconducting DC cable, the current is unevenly distributed, which in turn limits the current-carrying capacity of the superconducting DC cable.

[0005] To solve the above technical problem, the present invention provides a superconducting DC cable, which includes a hollow skeleton, a superconductor layer, and an external insulation layer arranged in sequence from the inside to the outside. The superconductor layer is arranged on the outside of the hollow skeleton. The number of the superconductor layers is multiple, and the multiple superconductor layers are sequentially wrapped around the outer periphery of the hollow skeleton from the inside to the outside. Each superconductor layer includes multiple double-wound sub-cables arranged in the same direction in a spiral manner, and each double-wound sub-cable includes a positive pole tape, a negative pole tape, and a sub-cable insulation layer. The sub-cable insulation layer is wrapped around the outer periphery of the positive pole tape and the negative pole tape, and the sub-cable insulation layer is used to provide an insulating environment for the positive pole tape and the negative pole tape; the external insulation layer is wound around the outer periphery of the superconductor layer to prevent the superconductor layer from contacting the external environment.

[0006] Further, the number of superconducting layers is five, and the five superconducting layers effectively ensure the current transmission efficiency.

[0007] In one embodiment, a cavity is provided inside the hollow skeleton, and a coolant is arranged in the cavity. The coolant circulates in the cavity to take away the heat outside the hollow skeleton.

[0008] In one embodiment, the hollow skeleton is a tubular conductor, and the material of the hollow skeleton is a metal material.

[0009] In one embodiment, the superconducting DC cable further includes an insulating and heat-conducting layer. The insulating and heat-conducting layer is arranged alternately with the superconducting layers, and an insulating and heat-conducting layer is provided between adjacent two superconducting layers. The insulating and heat-conducting layer is used to provide an insulating and heat-conducting environment and fix the superconducting layers.

[0010] In one embodiment, the positive belt and the negative belt are arranged in parallel with each other. Sub-cable insulating layers are provided on the outer peripheries of the positive belt and the negative belt, and a gap is provided between the positive belt and the negative belt.

[0011] In one embodiment, when the double-wound sub-cable is in the initial state, the length of the end face of the sub-cable insulating layer close to the hollow skeleton in the horizontal direction is greater than the length of the end face of the sub-cable insulating layer away from the hollow skeleton in the horizontal direction. The cross-section of the double-wound sub-cable before winding is trapezoidal.

[0012] In one embodiment, when the double-wound sub-cable is in the winding state, the positive belt, the negative belt and the sub-cable insulating layer all bend away from the hollow skeleton, and the cross-section of the double-wound sub-cable after winding is fan-shaped.

[0013] In one embodiment, the materials of the positive belt and the negative belt are high-temperature superconducting materials.

[0014] In one embodiment, the current value of the positive belt is different from the current value of the negative belt.

[0015] Further, the current values of the positive belt and the negative belt need to select high-temperature superconducting tapes with different critical current values (Ic) according to the actual current distribution characteristics of the cable. Make the ratio (I / Ic) of the actual current (I) passing through the superconducting tape in each sub-cable to the critical current (Ic) more average. When the cable load increases, the current can be distributed more evenly, thereby reducing the amount of superconducting tape used.

[0016] In one embodiment, both ends of the superconducting layer are connected to superconducting terminals for current transmission.

[0017] Compared with the prior art, the superconducting DC cable according to an embodiment of the present invention has the following beneficial effects: Through the design of the hollow skeleton, the hollow skeleton provides a stable structural basis for multiple layers of superconductors, preventing interlayer deformation or misalignment. The hollow design can accommodate the cooling medium liquid to ensure that the superconducting material operates in a low-temperature environment. Through the design of the superconductor layer, multiple superconductor layers are arranged in sequence from the inside to the outside, and each layer is composed of multiple double-wound sub-cables, which improves the overall current-carrying capacity. The double-wound sub-cable includes a positive pole band, a negative pole band, and a sub-cable insulating layer. The sub-cable insulating layer is designed to wrap the positive pole band and the negative pole band, effectively ensuring the electrical isolation between the positive and negative pole bands and between the sub-cables. The positive pole band and the negative pole band are arranged parallel to each other to form a self-canceling magnetic field structure, effectively reducing the suppression of the self-field effect on the critical current (Ic) of the superconducting tape, effectively avoiding the problem of uneven current distribution that is likely to occur when there are multiple tapes in the superconducting DC cable, and improving the overall stability. The design of the double-wound sub-cable with a co-directional spiral has the advantage of small gaps, which can reduce the winding stress caused by the gaps, and the sub-cable insulating layer has a relatively large thickness, which can also average and disperse the stress, so it is less affected by stress. Through the design of the external insulating layer, the external insulating layer mainly plays the role of electrical insulation and protection, improving the operating stability of the cable and reducing insulation faults, fixing the superconductor layer to prevent the superconductor layer from falling off, and maintaining the overall structure of the superconducting DC cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 FIG. is a schematic structural diagram of a superconducting DC cable according to an embodiment of the present invention.

[0019] Figure 2 FIG. is a schematic cross-sectional view of a superconducting DC cable according to an embodiment of the present invention.

[0020] Figure 3 FIG. is a schematic diagram of a double-wound sub-cable of a superconducting DC cable according to an embodiment of the present invention.

[0021] Figure 4 FIG. is a schematic diagram of a double-wound sub-cable of a superconducting DC cable according to an embodiment of the present invention in an initial state.

[0022] Figure 5 FIG. is a schematic diagram of a double-wound sub-cable of a superconducting DC cable according to an embodiment of the present invention in a wound state.

[0023] In the figure, 100, hollow skeleton; 11, cavity;

[0024] 200, superconductor layer; 21, double-wound sub-cable; 211, positive pole band; 212, negative pole band; 213, sub-cable insulating layer;

[0025] 300, insulating and heat-conducting layer;

[0026] 400, external insulating layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The specific embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0028] In the description of the present invention, it should be understood that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. The terms "mounted", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "height", "upper", "lower", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. in the present invention is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0030] As Figures 1 to 5 shown, a superconducting DC cable preferably provided in an embodiment of the present invention includes a hollow skeleton 100, a superconductor layer 200, and an external insulating layer 400 that are sequentially arranged from the inside to the outside. The superconductor layer 200 is disposed on the outer side of the hollow skeleton 100. The number of the superconductor layers 200 is multiple, and the multiple superconductor layers 200 are sequentially wrapped around the outer periphery of the hollow skeleton 100 from the inside to the outside. Each superconductor layer 200 includes a plurality of double-wound sub-cables 21 that are spirally arranged in the same direction, and each double-wound sub-cable 21 includes a positive electrode strip 211, a negative electrode strip 212, and a sub-cable insulating layer 213. The sub-cable insulating layer 213 is wrapped around the outer peripheries of the positive electrode strip 211 and the negative electrode strip 212, and the sub-cable insulating layer 213 is used to provide an insulating environment for the positive electrode strip 211 and the negative electrode strip 212; the external insulating layer 400 is wound around the outer periphery of the superconductor layer 200 to prevent the superconductor layer 200 from contacting the external environment.

[0031] Based on the above technical features, in the embodiments of the present invention, through the design of the hollow skeleton 100, the hollow skeleton 100 provides a stable structural basis for the multi-layer superconductor, preventing interlayer deformation or dislocation. The hollow design can accommodate the cooling medium liquid to ensure that the superconducting material works in a low-temperature environment; through the design of the superconductor layer 200, multiple superconductor layers 200 are arranged in sequence from the inside to the outside. Each layer is composed of multiple double-wound sub-cables 21. The current-carrying capacity of the conductor is proportional to the cross-sectional area. The multiple double-wound sub-cables 21 are arranged in the same-direction helix, which is equivalent to increasing the effective cross-sectional area of the conductor, thereby improving the overall current-carrying capacity. The double-wound sub-cable 21 includes a positive pole strip 211, a negative pole strip 212, and a sub-cable insulating layer 213. The sub-cable insulating layer 213 wraps the positive pole strip 211 and the negative pole strip 212, effectively ensuring the electrical isolation between the positive and negative poles and between the sub-cables. The positive pole strip 211 and the negative pole strip 212 are arranged parallel to each other to form a self-canceling magnetic field structure, effectively reducing the suppression of the critical current (Ic) of the superconducting tape by the self-field effect, and effectively avoiding the problem of uneven current distribution that is likely to occur when there are multiple tapes in the superconducting DC cable, improving the overall stability. The design of the double-wound sub-cables 21 winding around each other has the advantage of small gaps, which can reduce the winding stress caused by the gaps, and the sub-cable insulating layer 213 has a relatively large thickness, which can also average and disperse the stress, so it is less affected by stress; through the design of the external insulating layer 400, the external insulating layer 400 mainly plays the role of electrical insulation and protection, improving the operation stability of the cable and reducing insulation faults, fixing the superconductor layer 200 to prevent the superconductor layer 200 from falling off, and maintaining the overall structure of the superconducting DC cable.

[0032] Further, as Figures 1 to 2 shown, the number of layers of the superconductor layer 200 is five. The five-layer superconductor layer 200 effectively ensures the current transmission efficiency. The five-layer superconductor layer 200 and the insulating and heat-conducting layer 300 are alternately and helically arranged. The design of the five-layer superconductor layer 200 enables the superconductor layer 200 to still work independently when a local quench occurs in a certain layer during use, such as due to hot spots or mechanical damage, avoiding the failure of the entire cable, further reducing the fault risk. The five-layer structure supports local layer replacement or repair without shutting down the entire cable, improving the system availability and operation and maintenance efficiency, and significantly improving the current transmission efficiency. This structure is particularly suitable for large-capacity, long-distance DC power transmission scenarios, such as cross-sea power grid interconnection and renewable energy grid connection, promoting the development of superconducting cables towards higher performance and greater reliability.

[0033] As some embodiments of the present invention, such as Figures 1 to 2As shown in the figure, a cavity 11 is formed inside the hollow skeleton 100, and a coolant is provided in the cavity 11. The coolant circulates in the cavity 11 to take away the heat outside the hollow skeleton 100. Through the design of the cavity 11, the coolant (such as liquid nitrogen) can flow in the cavity 11 of the hollow skeleton 100, directly contact the inner wall of the skeleton, and quickly absorb the heat generated by the superconductor layer 200 through heat conduction. Compared with indirect cooling, the thermal resistance is lower, and the cooling efficiency is effectively improved to ensure that the high-temperature superconducting cable is always in a stable working environment.

[0034] As some embodiments of the present invention, such as Figures 1 to 2 As shown in the figure, the hollow skeleton 100 is a tubular conductor, and the material of the hollow skeleton 100 is a metal material. The thermal conductivity of the hollow skeleton 100 made of metal material is 5-10 times that of the composite material. The hollow skeleton 100 designed in this way enables the heat of the superconducting layer to be conducted to the coolant faster, effectively ensuring the cooling effect of the coolant.

[0035] Furthermore, the material of the hollow skeleton 100 is copper material. The thermal conductivity of copper is 1.6 times that of aluminum and 8 times that of stainless steel. Therefore, choosing copper material as the material of the hollow skeleton 100 enables the heat of the superconducting layer to be conducted to the coolant in the cavity 11 through the hollow skeleton 100 faster for cooling.

[0036] As some embodiments of the present invention, such as Figures 1 to 2 As shown in the figure, the superconducting DC cable further includes an insulating and heat-conducting layer 300. The insulating and heat-conducting layer 300 is arranged in an interleaved manner with the superconductor layer 200, and an insulating and heat-conducting layer 300 is provided between adjacent two superconductor layers 200. The insulating and heat-conducting layer 300 is used to provide an insulating and heat-conducting environment and fix the superconductor layer 200. Through this interleaved layout structure design, the insulating and heat-conducting layer 300 can closely wrap around the superconductor layer 200, providing a stable insulating and heat-conducting environment for the superconductor layer 200. The interleaved layout also helps to improve the overall structural stability of the cable and enhance the mechanical strength of the cable. An insulating and heat-conducting layer 300 is provided between adjacent two superconductor layers 200, which ensures that each superconductor layer 200 can obtain sufficient insulation and heat-conducting support, avoiding direct contact between the superconductor layers 200, thereby reducing the risk of electrical faults. At the same time, the insulating and heat-conducting layer 300 is made of materials with excellent insulation performance and heat-conducting performance, such as certain polymer composite materials or ceramic materials, etc. These materials can effectively prevent the leakage of current between the superconductor layers 200, ensuring the electrical safety of the cable. They can also quickly conduct the heat generated by the superconductor layer 200, reduce the working temperature of the cable, improve the current-carrying capacity and stability of the cable. The presence of the insulating and heat-conducting layer 300 also helps to evenly distribute the heat inside the cable and improve the heat dissipation efficiency of the cable.

[0037] As some embodiments of the present invention, such as Figures 3 to 5 shown, the positive electrode strip 211 and the negative electrode strip 212 are arranged in parallel with each other. Sub-cable insulating layers 213 are provided on the outer peripheries of both the positive electrode strip 211 and the negative electrode strip 212, and a gap is provided between the positive electrode strip 211 and the negative electrode strip 212. The positive electrode strip 211 and the negative electrode strip 212 serve as the core conductive parts of the cable. Being arranged in parallel with each other ensures the stable transmission of current in the cable. This parallel structure helps to reduce electromagnetic interference and improve the transmission efficiency of the cable. Sub-cable insulating layers 213 are provided on the outer peripheries of both the positive electrode strip 211 and the negative electrode strip 212. The sub-cable insulating layers 213 are made of materials with excellent insulating properties. It closely wraps around the outer peripheries of the positive electrode strip 211 and the negative electrode strip 212, effectively preventing current leakage and ensuring the electrical safety of the cable. At the same time, the sub-cable insulating layers 213 also play a role in protecting the positive electrode strip 211 and the negative electrode strip 212, preventing them from being damaged by the external environment. A gap is provided between the positive electrode strip 211 and the negative electrode strip 212. The existence of the gap further enhances the insulating performance of the cable, avoiding direct contact between the positive electrode strip 211 and the negative electrode strip 212. It helps to evenly distribute the electric field inside the cable, reduce the local electric field intensity, and thus improve the voltage withstand capacity of the cable. In addition, the gap can also serve as a heat dissipation channel for the heat inside the cable, contributing to the heat dissipation of the cable.

[0038] As some embodiments of the present invention, such as Figure 4 shown, when the double-wound sub-cable 21 is in the initial state, the length of the end face of the sub-cable insulating layer 213 close to the hollow skeleton 100 in the horizontal direction is greater than the length of the end face of the sub-cable insulating layer 213 away from the hollow skeleton 100 in the horizontal direction. The cross-section of the double-wound sub-cable 21 before winding is trapezoidal. In the initial state of the double-wound sub-cable 21, the length of the end face of the sub-cable insulating layer 213 close to the hollow skeleton 100 in the horizontal direction is deliberately designed to be greater than the end face away from the hollow skeleton 100. This length difference makes the sub-cable insulating layer 213 present a unique trapezoidal cross-section before winding. The design of the trapezoidal cross-section is not accidental but is carefully calculated to optimize the fitting degree and stability of the sub-cable during the winding process. The longer end face close to the hollow skeleton 100 helps to better fit with the skeleton during winding, reducing voids and looseness. The sub-cable insulating layer 213 with a trapezoidal cross-section can be more closely combined with the hollow skeleton 100 during the winding process, forming a stable structure. This design effectively reduces the deformation or damage that may occur when the cable is bent, stretched, or vibrated, improving the overall durability of the cable. At the same time, the trapezoidal design enables the double-wound sub-cable 21 to more efficiently utilize space during winding, reducing the voids inside the cable. This not only helps to reduce the overall size and weight of the cable but also improves the portability and flexibility of the cable.

[0039] As some embodiments of the present invention, such as Figure 5As shown, when the double-wound sub-cable 21 is in a wound state, the positive electrode strip 211, the negative electrode strip 212, and the sub-cable insulating layer 213 all bend away from the hollow skeleton 100, and the cross-section of the double-wound sub-cable 21 after winding is fan-shaped. When the double-wound sub-cable 21 is in a wound state, the positive electrode strip 211, the negative electrode strip 212, and the sub-cable insulating layer 213 all bend away from the hollow skeleton 100. Due to the bending of the positive electrode strip 211, the negative electrode strip 212, and the sub-cable insulating layer 213, the cross-section of the double-wound sub-cable 21 after winding presents a fan shape. This fan-shaped cross-section helps to optimize the internal structure of the cable, improve the space utilization rate, make the gap between the double-wound sub-cables 21 in the same layer smaller, and can better reduce the mechanical stress during the subsequent winding of each layer and keep the subsequent layers in a more regular geometric shape, effectively reducing the influence of electromagnetic and mechanical stresses on the DC superconductor layer 200.

[0040] Furthermore, the positive and negative superconducting strips arranged in this way can reduce the mutual influence of the magnetic fields between the sub-cables, making the current distribution between the sub-cables more uniform.

[0041] As some embodiments of the present invention, as Figures 3 to 5 shown, the materials of the positive electrode strip 211 and the negative electrode strip 212 are high-temperature superconducting materials. Both the positive electrode strip 211 and the negative electrode strip 212 are made of high-temperature superconducting materials. High-temperature superconducting materials have the characteristic of maintaining superconductivity at relatively high temperatures, which is the key point differentiating them from traditional superconducting materials. High-temperature superconducting materials have zero resistance in the superconducting state and can transmit current without loss. This characteristic enables the positive electrode strip 211 and the negative electrode strip 212 to significantly reduce energy loss and improve transmission efficiency when transmitting electrical energy.

[0042] As some embodiments of the present invention, as Figures 3 to 5 shown, the current value of the positive electrode strip 211 is different from the current value of the negative electrode strip 212. The difference in current values may bring about the optimization of the internal electromagnetic field of the cable, thereby reducing energy loss and electromagnetic interference, which helps to improve the transmission efficiency and stability of the cable and extend its service life.

[0043] Furthermore, the current values of the positive electrode strip 211 and the negative electrode strip 212 need to select high-temperature superconducting tapes with different critical current values (Ic) according to the actual current distribution characteristics of the cable, so that the ratio (I / Ic) of the actual current (I) passing through the superconducting tapes in each sub-cable to the critical current (Ic) is more average. When the cable load increases, the current can be more evenly distributed, thereby reducing the amount of superconducting tapes used. The current values of the positive electrode strip 211 and the negative electrode strip 212 are set according to the actual current distribution characteristics of the cable to ensure that they are different. High-temperature superconducting tapes with different critical current values (Ic) are selected to adapt to the different current requirements of the positive and negative electrodes. By precisely selecting superconducting tapes with different critical current values, the ratio (I / Ic) of the actual current (I) passing through the superconducting tapes in each sub-cable to the critical current (Ic) becomes more average. This design helps the current to be more evenly distributed to each superconducting tape when the cable load increases, avoiding local overheating and current overload. At the same time, by selecting positive electrode strip 211 and negative electrode strip 212 with different critical current values, the design parameters of the high-temperature superconducting cable can be flexibly adjusted according to actual needs. This design flexibility enables the high-temperature superconducting cable to better adapt to different application scenarios and load conditions.

[0044] As some embodiments of the present invention, such as Figure 1 shown, both ends of the superconductor layer 200 are connected to superconducting terminals for current transmission. Both ends of the superconductor layer 200 are connected to superconducting terminals to form a current transmission path. This connection method effectively ensures that the current can be efficiently and stably transmitted through the superconductor layer 200. As the starting and ending points of current transmission, the superconducting terminals not only provide interfaces for current access and extraction, but also have the function of protecting the superconductor layer 200 from external environmental interference. The superconductor layer 200 has the characteristic of zero resistance, so that the current has almost no loss during transmission. Through the connection with the superconducting terminals, this high-efficiency transmission characteristic can be fully exerted, improving the overall transmission efficiency of the cable. The connection design between the superconducting terminals and the superconductor layer 200 ensures the stability of current transmission. In the case of external environmental interference or load changes, the cable can maintain stable performance and reduce the possibility of failures. The design of the superconductor layer 200 effectively prevents the problem of uneven current distribution when there are multiple tapes in the superconducting DC cable.

[0045] In summary, the embodiment of the present invention provides a superconducting DC cable. Compared with the prior art, its beneficial effects are as follows: Through the design of the hollow skeleton 100, the hollow skeleton 100 provides a stable structural foundation for multiple layers of superconductors, preventing interlayer deformation or dislocation. The hollow design can accommodate the cooling medium liquid to ensure that the superconducting material operates in a low-temperature environment; Through the design of the superconductor layer 200, multiple superconductor layers 200 are arranged in sequence from the inside to the outside, and each layer is composed of multiple double-wound sub-cables 21, which improves the overall current-carrying capacity. The double-wound sub-cable 21 includes a positive pole strip 211, a negative pole strip 212, and a sub-cable insulating layer 213. The sub-cable insulating layer 213 wraps the positive pole strip 211 and the negative pole strip 212, effectively ensuring the electrical isolation between the positive and negative poles and between the sub-cables. The positive pole strip 211 and the negative pole strip 212 are arranged parallel to each other to form a self-canceling magnetic field structure, effectively reducing the suppression of the critical current (Ic) of the superconducting tape by the self-field effect, and effectively avoiding the problem of uneven current distribution that is likely to occur when there are multiple tape materials in the superconducting DC cable, improving the overall stability. The design of the double-wound sub-cable 21 with the same-direction helix has the advantage of small gaps, which can reduce the winding stress caused by the gaps, and the thickness of the sub-cable insulating layer 213 is relatively large, which can also average and disperse the stress, so it is less affected by stress; Through the design of the external insulating layer 400, the external insulating layer 400 mainly plays the roles of electrical insulation and protection, improving the operation stability of the cable and reducing insulation faults, fixing the superconductor layer 200 to prevent the superconductor layer 200 from falling off, and maintaining the overall structure of the superconducting DC cable.

[0046] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and replacements can still be made, and these improvements and replacements should also be regarded as the protection scope of the present invention.

Claims

1. A superconducting DC cable, characterized in that, Comprising: A hollow skeleton, a superconductor layer, and an external insulation layer arranged in sequence from the inside to the outside, The superconductor layer is arranged on the outer side of the hollow skeleton. The number of the superconductor layers is multiple, and the multiple superconductor layers are sequentially wrapped around the outer periphery of the hollow skeleton from the inside to the outside. Each superconductor layer includes a plurality of double-wound sub-cables arranged in the same direction in a spiral manner, and each double-wound sub-cable includes a positive pole band, a negative pole band, and a sub-cable insulation layer. The sub-cable insulation layer is wrapped around the outer periphery of the positive pole band and the negative pole band, and the sub-cable insulation layer is used to provide an insulating environment for the positive pole band and the negative pole band; The external insulation layer is wound around the outer periphery of the superconductor layer to prevent the superconductor layer from contacting the external environment.

2. The superconducting DC cable according to claim 1, wherein A cavity is formed inside the hollow skeleton, and a coolant is arranged in the cavity. The coolant circulates in the cavity to take away the heat outside the hollow skeleton.

3. The superconducting DC cable according to claim 2, characterized in that, The hollow skeleton is a tubular conductor, and the material of the hollow skeleton is a metal material.

4. The superconducting DC cable according to claim 1, characterized in that, It further includes an insulating and heat-conducting layer. The insulating and heat-conducting layer is arranged in an interleaved manner with the superconductor layer, and the insulating and heat-conducting layer is arranged between adjacent two superconductor layers. The insulating and heat-conducting layer is used to provide an insulating and heat-conducting environment and fix the superconductor layer.

5. The superconducting DC cable according to claim 1, wherein, The positive pole band and the negative pole band are arranged in parallel with each other. Sub-cable insulation layers are arranged on the outer peripheries of the positive pole band and the negative pole band, and a gap is arranged between the positive pole band and the negative pole band.

6. The superconducting DC cable according to claim 5, characterized in that, When the double-wound sub-cable is in an initial state, the length of the end face of the sub-cable insulation layer close to the hollow skeleton in the horizontal direction is greater than the length of the end face of the sub-cable insulation layer away from the hollow skeleton in the horizontal direction. The cross-section of the double-wound sub-cable before winding is trapezoidal.

7. The superconducting DC cable according to claim 6, characterized in that, When the double-wound sub-cable is in a wound state, the positive pole band, the negative pole band, and the sub-cable insulation layer are all bent in a direction away from the hollow skeleton. The cross-section of the double-wound sub-cable after winding is fan-shaped.

8. The superconducting DC cable according to claim 7, characterized in that, The materials of the positive pole band and the negative pole band are high-temperature superconducting materials.

9. The superconducting DC cable according to claim 8, characterized in that, The current value of the positive pole band is different from the current value of the negative pole band.

10. The superconducting DC cable according to claim 1, wherein Both ends of the superconductor layer are connected to superconducting terminals for transmitting current.

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