JP4986291B2 - Superconducting cable - Google Patents

Description

  The present invention relates to a superconducting cable used for long-distance and large-capacity power transmission, and more particularly to a superconducting cable including a superconducting layer formed of a superconducting tape having a reduced thickness.

  As a superconducting tape, a Bi-based superconducting tape represented by a Bi-Sr-Ca-Cu-O tape wire is being put into practical use. This Bi-based superconducting tape is a tape wire having a structure in which, for example, a plurality of superconducting filaments made of Bi2223 phase are embedded in a stabilizing material such as silver. For example, as shown in FIG. 4, the cross section is formed in a tape shape by covering a large number of superconducting filaments 21b made of a Bi-based oxide superconductor with a metal sheath (metal stabilizing material) 21a made of silver or the like. . The Bi-based superconducting tape 21 forms a cable core 9 as shown in FIG. That is, the cable core 9 is a multi-layered Bi wound around the outer periphery of the former 1 composed of a stranded wire or a hollow pipe formed by twisting strands made of a normal conducting material such as Cu via an interlayer insulation 16. A superconducting conductor layer 2 formed by a system superconducting tape 21, an insulating layer 3 made of kraft paper wound around the outer periphery thereof, a composite paper laminated with a kraft paper and a polyolefin film, and the like, and an interlayer insulating layer 17 interposed therebetween. The superconducting shield layer 4 is composed of a plurality of layers of Bi-based superconducting tape 21 wound around and an outer layer 18 wound around the outer periphery thereof via an interlayer insulation 17. Three such cable cores 9 are forcibly twisted in a state in which a tensile force is applied in the axial direction, and are formed by an inner tube 6 and an outer tube 7, for example, as shown in FIG. The refrigerant flow passage 5 is formed in the inner pipe 6 by being inserted into the double heat insulating pipe. The outer tube 7 is covered with an anticorrosion layer 8, and the space between the inner tube 6 and the outer tube 7 is evacuated to form a vacuum layer. In this way, a three-core collective superconducting cable 10 for alternating current is formed.

On the other hand, development of RE (rare earth) -based superconducting thin films (thin-film systems) is being promoted as next-generation superconducting tapes (for example, Patent Document 1). For example, as shown in FIG. 7, the RE superconducting thin film 11 is formed by sequentially laminating an intermediate layer 13, a superconducting thin film 14, and a protective layer 15 on a tape-shaped metal reinforcing plate 12. As a specific example, for example, Hastelloy (registered trademark) is used as the metal reinforcing plate 12, YSZ is used as the intermediate layer 13, Y-type 123 (YBa ₂ Cu ₃ Oy) thin film is used as the superconducting thin film 14, and silver is used as the protective layer 15. . Usually, the intermediate layer 13 and the superconducting thin film 14 are formed only on one side of the metal reinforcing plate 12 by laser vapor deposition or the like. Such a RE-based superconducting thin film 11 can be formed thin and has a relatively excellent strength against tensile force due to the presence of the metal reinforcing plate 12. Even when the three-core superconducting cable 10 is formed using such a RE-based superconducting thin film 11, it is configured in the same manner as the Bi-based superconducting tape 21 (see FIG. 6).
JP 2001-31418

  By the way, if an alternating current is passed through the three-conductor-type superconducting cable 10 as shown in FIG. 6, a slight heat is generated due to a minute loss in the superconducting tape, so that cooling for suppressing a temperature rise is necessary. If the AC loss is large, heat generation also increases, so a large refrigerator must be prepared, and the economic efficiency is significantly impaired. In the case of a superconducting cable, since a magnetic field is formed in the circumferential direction of the conductor, the AC loss can be reduced as the thickness of the superconducting tape forming the superconducting layer (superconducting conductor layer or superconducting shield layer) is reduced. Therefore, in order to reduce AC loss, it is desirable to make the thickness of each tape-shaped superconducting tape (Bi-based superconducting tape 21 or RE-based superconducting thin film 11) as thin as possible.

  However, in the current Bi-based superconducting tape manufacturing equipment, if the thickness of the superconducting tape is reduced, the width must be reduced. If the thickness and width of individual superconducting tapes are reduced too much, the number of superconducting tapes required to form the superconducting layer will increase, and a large number of reels will be required to feed the superconducting tapes, making it impossible to manufacture with existing equipment. . In addition, the required strength cannot be ensured due to a decrease in mechanical strength, or the increase in the number of superconducting tapes makes it difficult to properly secure the spacing between the individual superconducting tapes during winding, resulting in entanglement and climbing. Problems in the production stage occur. Further, when the superconducting cable as described above is used for direct current, if the number of superconducting tapes is increased in order to increase the capacity, problems at the production stage occur as in the case of alternating current. For this reason, a countermeasure for solving these problems has been demanded.

  On the other hand, in the thin film system (RE-based superconducting thin film 11), slit processing by an electron laser or the like is possible, so that the width can be easily adjusted when forming a superconducting tape. Originally, the superconducting thin film 14 has a thickness of several nanometers, so there is little electrical loss (alternating current loss). Therefore, when forming the superconducting layer of the superconducting cable, the problem is how much the width of the superconducting tape should be set. With respect to this point, as in the case of the Bi-based superconducting tape 21, if the width is reduced too much, a large number of reels for feeding the superconducting tape are required, which cannot be handled by existing equipment. In addition, if the number of superconducting tapes increases too much due to the reduction in width, there is a concern that troubles such as tangling or getting on may occur in the winding process.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a superconducting cable including a superconducting layer formed of a superconducting composite wire that can ensure the required mechanical strength even if the thickness of the superconducting tape is reduced. And

The superconducting cable of the present invention is a superconducting cable in which a superconducting layer formed by winding a superconducting composite wire around the outer periphery of the former is disposed in a plurality of layers via an insulating layer,
The superconducting composite wire is formed by integrating a single superconducting tape or a plurality of superconducting tapes arranged in parallel with each other on a reinforcing substrate, and forms a superconducting layer disposed inside the superconducting composite wire. Is set to be narrower than the width of the superconducting composite wire forming the superconducting layer disposed on the outside.

  Since the strength of the superconducting composite wire is reinforced by the reinforcing substrate even if the superconducting tape is thinly formed, the superconducting tape can be made thin without reducing the mechanical strength. In addition, since a plurality of superconducting tapes can be integrated, it is possible to reduce the number of superconducting composite wires necessary to form a superconducting layer of a superconducting cable while achieving a thin superconducting tape. . Therefore, in the winding process in the production stage of the superconducting cable, the number of reels for feeding the superconducting composite wire can be reduced, and the existing equipment can be handled. In addition, since the required mechanical strength can be ensured, it is possible to reduce the occurrence of troubles such as breakage, entanglement, and climbing of the superconducting composite wire during the winding process in the production stage.

  When such a superconducting composite wire is used for a superconducting cable for alternating current, the width of the superconducting composite wire forming the superconducting conductor layer having a small diameter is larger than the width of the superconducting composite wire forming the superconducting shield layer having a large diameter. Since the superconducting conductor layer can be formed in a well-rounded shape without being polygonal, AC loss can be reduced. In addition, since the superconducting shield layer can be made thin without forming a polygon even if the width of the superconducting composite wire is widened, AC loss is reduced by reducing the number of superconducting composite wires necessary to form the same layer. Can be reduced. On the other hand, when increasing the capacity for direct current use, a larger capacity can be achieved with a smaller number of superconducting composite wires, so troubles such as the superconducting composite wires breaking, entangled, or climbing during the winding process. Can be reduced. The superconducting layer corresponds to a superconducting conductor layer and a superconducting shield layer in an AC superconducting cable, and an inner superconducting layer and an outer superconducting layer in a DC superconducting cable.

  The number of superconducting tapes of the superconducting composite wire that forms the superconducting layer disposed on the outside is set to be greater than the number of superconducting tapes of the superconducting composite wire that forms the superconducting layer disposed on the inside. You may do it. In this way, in the superconducting composite wire that forms the inner superconducting layer with a small diameter, by reducing the number of superconducting tapes, the width of the superconducting composite wire is narrowed, and the superconducting layer is made polygonal. Can be formed into a well-rounded shape. Moreover, in the superconducting composite wire forming the outer superconducting layer having a large diameter, the number of superconducting tapes can be increased and the number of necessary superconducting composite wires can be reduced. As a result, in the winding process in the production stage of the superconducting cable, the number of reels for feeding the superconducting composite wire can be reduced, and the existing equipment can be handled.

  The width of the superconducting composite wire may be set substantially proportional to the diameter of the superconducting layer formed by the superconducting composite wire. When such a superconducting cable is used for alternating current, the superconducting conductor layer having a small inner diameter can be formed into a well-rounded shape without making it polygonal, thereby reducing alternating current loss. it can. In addition, since the thickness of the superconducting shield layer can be reduced even if the width of the superconducting composite wire is widened, the number of superconducting composite wires required to form the same layer can be reduced to reduce AC loss. . On the other hand, when increasing the capacity for direct current use, a larger capacity can be achieved with a smaller number of superconducting composite wires, so troubles such as the superconducting composite wires breaking, entangled, or climbing during the winding process. Can be reduced. In addition, if the width of the superconducting composite wire is set approximately in proportion to the diameter of the superconducting layer, the number of superconducting composite wires required for the superconducting layer formed on the inside and the superconducting power necessary for the superconducting layer formed on the outside Since the number of composite wires can be made to coincide with each other, there is an advantage that the number of bobbins for feeding the superconducting composite wire forming the inner and outer superconducting layers can be set to the same number in the superconducting cable manufacturing stage.

  The superconducting tape may be a Bi-based superconducting tape formed in a tape shape. As this Bi-based superconducting tape, for example, a thin film formed by embedding a plurality of Bi2223 superconducting filaments in a stabilizing material such as silver can be used.

The superconducting tape may be an RE-based superconducting thin film formed in a tape shape. This RE-based superconducting thin film is formed by sequentially laminating an intermediate layer, a superconducting thin film, and a protective layer on a tape-shaped metal reinforcing plate. For example, there may be mentioned those in which Hastelloy (registered trademark) is used as a metal reinforcing plate, YSZ is used as an intermediate layer, Y-type 123 (YBa ₂ Cu ₃ Oy) thin film is used as a superconducting thin film, and silver is used as a protective layer. In addition, you may use the metal reinforcement board which consists of Hastelloy etc. as a reinforcement board | substrate.

  The superconducting layer may include a superconducting conductor layer and a superconducting shield layer disposed outside the superconducting conductor layer. When a superconducting cable for alternating current is constructed in this way, the superconducting conductor layer is formed into a neat circular shape without making it polygonal by using a narrow superconducting composite wire for the superconducting conductor layer with a small diameter. be able to. On the other hand, by using a superconducting composite wire having a wide width without increasing the thickness, the superconducting layer can be formed by winding at a high density in the radial direction. With such a configuration, AC loss can be reduced. In addition, the number of bobbins for feeding a superconducting composite wire forming the superconducting layer can be reduced.

  The superconducting layer may include an inner superconducting layer and an outer superconducting layer disposed on the outer side. When a DC superconducting cable is constructed in this way to increase the capacity, the capacity can be increased with a smaller number of superconducting composite wires, so the superconducting composite wire breaks during the winding process. It is possible to reduce the occurrence of troubles such as entanglement, entanglement, and riding.

  In the superconducting cable of the present invention, the width of the superconducting composite wire that forms the superconducting layer disposed inside is set narrower than the width of the superconducting composite wire that forms the superconducting layer disposed outside. Since the superconducting layer can be formed in a well-rounded shape without making it polygonal, AC loss can be reduced when used for AC. In addition, by using a superconducting composite wire with a wide width without increasing the thickness for the superconducting shield layer with a large diameter, the superconducting layer can be formed by being wound at a high density in the radial direction. Loss can be reduced. On the other hand, when increasing the capacity for direct current use, a larger capacity can be achieved with a smaller number of superconducting composite wires, so troubles such as the superconducting composite wires breaking, entangled, or climbing during the winding process. Can be reduced.

  Hereinafter, a superconducting composite wire according to an embodiment of the present invention will be described in detail with reference to the drawings.

1 (a) is a cross-sectional view of a cable core 29 of the superconducting cable 20 for alternating current, (b) is a sectional view of the superconducting composite wire _{S 1} for forming a superconducting conductor layer 22, (c), the superconducting shield layer 24 FIG. 4D is a cross-sectional view of the superconducting composite wire S ₂ that forms, and FIG. FIG. 2A is a cross-sectional view showing an example of the superconducting composite wire S, and FIG. 2B is a cross-sectional view showing another example. 3A to 3C are cross-sectional views showing other examples of the superconducting composite wire S. FIG. First, as shown in FIG. 1D, the superconducting cable 20 has a cushion layer C and a superconducting conductor layer 22 formed by winding a superconducting composite wire S around the former F with the former F as a center. A cable core 29 including an insulating layer 23 made of kraft paper or a composite paper laminated with kraft paper and a polyolefin film and a superconducting shield layer 24 formed by winding the superconducting composite wire S is formed. . The three cable cores 29 are twisted together and inserted into a double heat insulating pipe formed by the inner pipe 26 and the outer pipe 27, and the refrigerant flow passage 25 is formed in the inner pipe 26. The outer tube 27 is covered with an anticorrosion layer 28, and the space between the inner tube 26 and the outer tube 27 is evacuated to form a vacuum layer.

In the superconducting cable 20 configured as described above, the superconducting composite wire S (S ₁ , S ₂ ) forming the superconducting conductor layer 22 and the superconducting shield layer 24 is, for example, shown in FIGS. As described above, the superconducting tape 31 is integrally formed on the reinforcing substrate 32. In the example shown in FIG. 2A, for example, reinforcing substrates 32 and 32 are integrally formed on both surfaces of a superconducting tape 31 made of one Bi-based superconducting tape by solder bonding or the like. In the example shown in FIG. 2B, for example, reinforcing substrates 32 and 32 are integrated by soldering or the like on both surfaces of superconducting tapes 31 and 31 made of two Bi-based superconducting tapes arranged in parallel to each other. Is done. The reinforcing substrate 32 can be formed of, for example, copper, an alloy thereof, stainless steel, or the like . By using such a reinforcing substrate 32, a superconducting composite wire S having required mechanical strength (tensile strength and bending strength) and sufficient flexibility can be formed. Further, as a material of the reinforcing substrate 32, not only such a conductive metal material but also a polyimide tape having excellent insulation and heat resistance can be used. When a RE superconducting thin film is used as the superconducting tape 31, a metal reinforcing plate made of, for example, Hastelloy (registered trademark) may be set to a required thickness and used as the reinforcing substrate 32.

  The superconducting composite wire S configured as described above is thinned without increasing the mechanical strength because the strength is reinforced by the reinforcing substrate 32 even if the superconducting tape 31 is formed thin. can do. In addition, since a plurality of superconducting tapes 31 can be integrated, the superconducting tape 31 can be made thin and the superconducting layers (superconducting conductor layer 22 and superconducting shield layer 24) of the superconducting cable 20 can be formed. It is possible to reduce the number of superconducting composite wire rods S required. Therefore, in the winding process in the manufacturing stage, the number of reels for feeding the superconducting composite wire S can be reduced, and the existing equipment can be handled. In addition, since the required mechanical strength can be ensured, it is possible to reduce the occurrence of troubles such as the superconducting composite wire S being broken, entangled or climbed during the winding process in the production stage. 2A and 2B, since the superconducting composite tape 31 is sandwiched between the reinforcing substrates 32, the superconducting composite tape 31 can be protected at the stage of manufacturing the superconducting cable 20. As shown in the figure, if the width of the reinforcing substrate 32 is set to be slightly larger than the entire width of the superconducting tape 31, the superconducting tape 31 can be protected more effectively. Further, if the outer edge e of the reinforcing substrate 32 is formed in a chamfered shape, the insulating tape can be prevented from being damaged when the insulating layer 23 is formed on the superconducting conductor layer 22.

Then, the widths b ₁ and b ₂ of the superconducting composite wire S are set to values substantially proportional to the diameters r ₁ and r ₂ of the superconducting layers 22 and 24, as shown in FIGS. Is preferred. For example, if the ratio of the radius _{r 2} of a radius _{r 1} and the superconducting shield layer 24 of the superconducting layers 22 is 1/2, also set to 1/2 ratio of the width _b 1, _{b 2} of the superconducting composite wire _S 1, _{S 2} To do. The width _b 1, _{b 2} are also different from the thickness t of the superconducting composite wire _S 1, _{S 2} are the same. In this case, if the number of superconducting tapes 31 constituting the superconducting composite wire rods S ₁ and S ₂ is n ₁ and n ₂ , 2πr ₁ / n ₁ = 2πr ₂ / n ₂ (1) is satisfied. Is preferred. Therefore, in the case of r ₂ = 2r ₁ , n ₂ = 2n ₁ from the formula (1), and the superconducting composite wire S ₁ forming the superconducting conductor layer 22 is, for example, one piece as shown in FIG. a structure in which reinforced the superconducting tape 31 in the reinforcing substrate 32, the superconducting composite wire S ₂ forming the outer superconducting shield layer 24, the reinforcing two superconducting tapes 31 and 31 as shown in FIG. 2 (b) for example, a substrate It can be set as the structure reinforced by 32. Thereby, since the required number of the superconducting composite wire S can be made the same in the superconducting conductor layer 22 and the superconducting shield layer 24, the work in the winding process of the superconducting composite wire S in the manufacturing stage of the superconducting cable 20 is possible. Good. Incidentally, in the superconducting composite wire S shown in FIGS. 2A and 2B, for example, the width of the superconducting tape 31 is 2.6 mm, the thickness is 0.18 mm , and the width b ₁ of the reinforcing substrate 32 of the superconducting composite wire S ₁ is 2.7 mm. can be set thickness t = 20 to 100 [mu] m, the width _{b 2} = 5.3 mm of the reinforcing substrate 32 of the superconducting composite wire _{S 2,} a thickness = 20 to 100 [mu] m.

By selecting the width of the superconducting composite wire S in this way, the inner superconducting conductor layer 22 can be formed in a well-rounded shape without making it polygonal, and AC loss can be reduced. Further, as shown in FIG. 2 (b), it is integrated two of the superconducting tape 31, since the thickness of the superconducting composite wire S ₂ is not increased, in order to form a superconducting shield layer 24 The AC loss can be reduced by reducing the number of necessary superconducting composite wires S. Note that, when the superconducting layer 22 (24) is polygonalized, the magnetic field formed in the radial direction is expanded, so that AC loss increases. On the other hand, when a superconducting cable 20 for direct current is formed with such a superconducting composite wire S to increase the capacity, the capacity can be increased with a smaller number of superconducting composite wire S. In the winding process of the superconducting composite wire S, it is possible to reduce the occurrence of troubles such as the superconducting composite wire S being broken, entangled or climbed. In the DC superconducting cable 20, the inner superconducting layer 22 and the outer superconducting layer 24 correspond to the superconducting layer.

  The width of the superconducting tape 31 constituting the superconducting composite wire S can be set to 1.5 to 4.5 mm, and 1 to 5 superconducting tapes 31 can be integrated with the reinforcing substrate 32. The width of the reinforcing substrate 32 can be set to 2 to 10 mm. With such a width, the required mechanical strength and sufficient flexibility can be ensured by using, for example, copper, an alloy thereof, stainless steel or the like as a material. In addition, by using these conductors, when a short circuit current is generated, the superconducting tape 31 can be protected by causing the short circuit current to flow through the reinforcing substrate 32. When the width of the reinforcing substrate 32 is less than 2 mm, it becomes difficult for the superconducting composite wire S to ensure the required mechanical strength, and it becomes easy to twist. If it exceeds 10 mm, when the superconducting composite wire S is wound to form a superconducting layer, its outer shape is likely to be polygonal. In particular, the inner superconducting layer is difficult to adjust to a shape close to a circle.

  In the superconducting composite wire S, for example, as shown in FIGS. 3A and 3B, the reinforcing substrate 32 may be integrated only on one side of the superconducting tape 31. In this way, when the superconducting layer is formed with the superconducting composite wire S formed with the superconducting tape 31 only on one side of the reinforcing substrate 32, the superconducting cable can be formed by winding the superconducting tape 31 on the outer side. In the connecting portion, since the connecting member can be directly connected to the superconducting layer, there is an advantage that the connection resistance can be reduced. In the example shown in FIGS. 3B and 3C, a restricting portion 32 a for suppressing the movement of the superconducting tape 31 in the width direction is formed on the reinforcing substrate 32. Such a restriction | limiting part 32a may be formed in the protrusion shape etc. for every predetermined interval in the longitudinal direction, for example, and may be formed in the protrusion shape which followed the longitudinal direction. By forming such a restricting portion 32a, the superconducting composite wire S is wound around the former (or insulating layer) in order to form a superconducting layer from the step of integrating the plurality of superconducting tapes 31 into the reinforcing substrate 32. Even if the superconducting tape 31 and the reinforcing substrate 32 are affected by various external forces or heat during the process of twisting the cable core and the step of using the cable core, the superconducting tape 31 is attached to the reinforcing substrate 32. It can be kept in a stable alignment state. In the example shown in FIG. 3C, the restricting portion 32 a is formed on the upper and lower reinforcing substrates 32, but the restricting portion 32 a may be formed only on one reinforcing substrate 32. It should be noted that the present invention is not limited to the embodiment, and can be freely improved, changed, etc. as necessary without departing from the gist of the invention.

  Since the superconducting cable of the present invention can reduce AC loss, it can be suitably used for long-distance and large-capacity AC power transmission.

(A) is sectional drawing of the cable core of the superconducting cable which concerns on embodiment of this invention, (b) is sectional drawing of the superconducting composite wire which forms a superconducting conductor layer, (c) forms a superconducting shield layer Sectional drawing of the superconducting composite wire to perform, (d) is a sectional view of the superconducting cable. (A) is sectional drawing which shows an example of a superconducting composite wire, (b) is sectional drawing which shows another example. (A) is sectional drawing which shows the other example of a superconducting composite wire, (b) is sectional drawing which shows a different example, (c) is sectional drawing which shows a further different example. It is sectional drawing of a Bi type superconducting tape. It is a partially broken perspective view of a cable core. It is sectional drawing of a 3 core lump-sum type superconducting cable. It is a partial fracture perspective view of RE type superconducting thin film.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Former 2 Superconducting layer (superconducting conductor layer) 3 Insulating layer 4 Superconducting layer (superconducting shield layer) 5 Refrigerant flow path 6 Inner tube 7 Outer tube 8 Corrosion protection layer 9 Cable core 10 Superconducting cable 11 RE system superconducting thin film 12 Metal reinforcement plate 13 Intermediate layer 14 Superconducting thin film 15 Protective layer 16 Interlayer insulation 17 Interlayer insulation 18 Outer layer 20 Superconducting cable 21 Bi-based superconducting tape 21a Metal sheath 21b Superconducting filament 22 Superconducting layer (superconducting conductor layer) 23 Insulating layer 24 Superconducting layer (superconducting shield layer) 25 Refrigerant flow passage 26 Inner tube 27 Outer tube 28 Corrosion protection layer 29 Cable core F Former S, S ₁ , S ₂ Superconducting composite wire e Outer edge C Cushion layer 31 Superconducting tape 32 Reinforcement substrate 32a Restriction part

Claims (7)

A superconducting layer formed by winding a superconducting composite wire around the outer periphery of the former is a superconducting cable provided with a plurality of layers via an insulating layer,
The superconducting composite wire is on both sides of one or a plurality of superconducting tapes arranged in parallel with each other, are integrally formed of copper or an alloy, the reinforcing substrate composed of a metal material conductor such as stainless steel, And,
A superconducting cable, characterized in that a width of the superconducting composite wire forming the superconducting layer disposed inside is set narrower than a width of the superconducting composite wire forming the superconducting layer disposed outside.   The number of superconducting tapes of the superconducting composite wire that forms the superconducting layer disposed on the outside is set to be greater than the number of superconducting tapes of the superconducting composite wire that forms the superconducting layer disposed on the inside. The superconducting cable according to claim 1. 3. The superconducting cable according to claim 1, wherein a width of the superconducting composite wire is set substantially in proportion to a diameter of a superconducting layer formed by the superconducting composite wire.   The superconducting cable according to any one of claims 1 to 3, wherein the superconducting tape is a Bi-based superconducting tape.   The superconducting cable according to any one of claims 1 to 3, wherein the superconducting tape is a RE-based superconducting thin film formed in a tape shape.   The superconducting cable according to any one of claims 1 to 5, wherein the superconducting layer includes a superconducting conductor layer and a superconducting shield layer disposed outside the superconducting conductor layer.   The superconducting cable according to claim 1, wherein the superconducting layer includes an inner superconducting layer and an outer superconducting layer disposed outside the inner superconducting layer.

Images