JP2010092715A - Superconductive cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a superconductive cable which can prevent expansion of a diameter even if a fiber optic for monitoring the temperature of a cable is provided. <P>SOLUTION: The superconductive cable is provided with the fiber optic F, a former 11, and a superconductive conductor layer arranged at the outer circumference of the former 11. The former 11 has a stranded wire structure in which a plurality of strands 1, 2 are stranded. The fiber optic F is combined in the former 11 so that it can measure the temperature of the superconductive cable throughout the whole length at further inside than the superconductive conductor layer. Since the fiber optic F is arranged at inside of the superconductive conductor layer, a new layer for arranging the fiber optic F is not required additionally in the superconductive cable, and a large diameter of the cable can be avoided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a superconducting cable including an optical fiber, a former, and a superconducting conductor layer disposed on the outer periphery of the former, and relates to a superconducting cable having a function of detecting a cable temperature during operation.

  A superconducting cable used for power transmission has a configuration in which a superconducting cable core is housed in a heat insulating tube. The superconducting cable core includes a former, a superconducting conductor layer, an insulating layer, a superconducting shield layer, and a protective layer in order from the center. Usually, both the superconducting conductor layer and the superconducting shield layer are formed of a superconducting wire. On the other hand, the heat insulating pipe has a configuration in which a heat insulating material is disposed between a double pipe composed of an inner pipe and an outer pipe having a corrugated structure, and the inside of the double pipe is evacuated.

  The superconducting cable as described above is operated in a state cooled to a very low temperature. However, if the cable temperature rises due to some factor, the superconducting wire may change from the superconducting state to the normal conducting state, and the cable may be damaged. . Therefore, temperature management of the cable during operation of the superconducting cable is very important. In this regard, for example, Patent Document 1 proposes a superconducting cable including a temperature monitoring layer for monitoring the temperature of the cable during operation. The temperature monitoring layer is composed of a metal layer formed by winding a metal tape material, and an optical fiber that is disposed in a groove formed in the metal layer and measures the temperature, and is disposed on the outer peripheral side of the superconducting conductor layer or the superconducting shield layer. Is provided.

JP 2006-59753 A

  However, the superconducting cable of Patent Document 1 has the following problems. A superconducting cable is characterized by being capable of transmitting a large amount of power while being smaller than a conventional normal conducting cable. However, it is clear that the diameter of the cable core is increased by the temperature monitoring layer. For example, in a superconducting cable having a structure in which a plurality of cores are housed in a heat insulating tube, a diameter that cannot be ignored is incurred.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide a superconducting cable that does not increase in diameter even if it has an optical fiber for monitoring the temperature of the superconducting cable over the longitudinal direction of the cable. It is to provide.

  Conventionally, it has been considered that the position where the optical fiber is disposed should be close to the layer of the superconducting wire that is actually the current flow path. However, as a result of various studies by the present inventors, it is not always necessary to directly monitor the temperature of the superconducting conductor layer, and if it is possible to grasp at which position of the superconducting cable the local temperature rise occurs, We found that it was enough to avoid the situation where the superconducting cable was operated in an abnormal state. Based on this finding, the present invention is defined below.

  The superconducting cable of the present invention is a superconducting cable comprising an optical fiber, a former, and a superconducting conductor layer disposed on the outer periphery of the former, wherein the former is formed by twisting a plurality of strands. The optical fiber is combined with the former so that the temperature of the superconducting cable can be measured over the entire length inside the superconducting conductor layer.

  According to the above configuration, since the optical fiber for monitoring the temperature during operation of the superconducting cable is at the position of the former, a new layer for arranging the optical fiber is not added to the superconducting cable. Can be avoided.

  In the superconducting cable according to the present invention, the configuration in which the optical fiber is combined with the former inside the superconducting conductor layer includes the following four configurations.

<First configuration>
As one form of the superconducting cable of the present invention, there may be a case where a plurality of fan-shaped segments formed by twisting a plurality of strands are aggregated so that a hollow portion is formed at the center of the former. In this case, the optical fiber provided in the superconducting cable can be configured to be inserted into the hollow portion formed in the center of the former.

  According to the said structure, an optical fiber can be arrange | positioned effectively using the hollow part which the former | former of a segment structure is originally equipped. Moreover, according to this structure, an optical fiber can be effectively protected with respect to the stress which acts from the exterior of a cable core.

<Second configuration>
As one form of the superconducting cable of the present invention, a part of the strands constituting the former can be replaced with an optical fiber.

  According to the above configuration, since the optical fiber is a part of the former, the superconducting cable does not increase in diameter, and the optical fiber can be effectively protected against stress acting from the outside of the cable core. You can also.

<Third configuration>
As one form of the superconducting cable of the present invention, it is possible to adopt a configuration in which optical fibers are arranged along strands between strands in the outer periphery of the former.

  According to the said structure, the former of a conventional strand wire structure can be used as it is, and an optical fiber can be arrange | positioned later to the former. Further, when the optical fiber is arranged in the former, it is only necessary to follow the optical fiber, so that unnecessary stress is not applied to the optical fiber.

<Fourth configuration>
As one form of the superconducting cable of the present invention, a cushion layer formed by winding a tape material may be provided between the former and the superconducting conductor layer. In this case, it can be set as the structure which arrange | positions an optical fiber along the tape material which comprises a cushion layer.

  Usually, in the superconducting cable, when forming the superconducting conductor layer, a cushion layer formed by winding a tape material around the former is provided so that the superconducting wire can be wound around a smooth surface. Therefore, if the optical fiber is arranged along the cushion layer as in the fourth configuration, the optical fiber can be arranged at a position where it is difficult to damage without increasing the outer diameter of the separate cable core.

<Others>
In addition, the optical fiber may be arranged in a state of being housed in a metal tube that protects the optical fiber. The metal tube may have any inner diameter that is slightly larger than the outer diameter of the optical fiber.

  According to this configuration, the optical fiber can be more effectively protected.

  According to the superconducting cable of the present invention, a new layer for arranging the optical fiber is not added to the superconducting cable, and the diameter of the cable can be avoided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In describing the embodiment, first, the overall configuration of the superconducting cable will be described.

<Overall configuration of superconducting cable>
FIG. 5 is a sectional view of a superconducting cable of a three-core type. The superconducting cable 100 has a three-core superconducting cable core 10 and a heat insulating tube 20 that houses the core 10.

  The core 10 includes, in order from the center, a former 11, a cushion layer (not shown), a superconducting conductor layer 12, an internal semiconductive layer (not shown), an insulating layer 13, an external semiconductive layer (not shown), and a superconducting shield. It has a layer 14 and a protective layer 15. Of these layers, a superconducting wire is used for the conductor layer 12 and the shield layer 14. The superconducting wire constituting the core 10 is maintained in a superconducting state by circulating a refrigerant (for example, liquid nitrogen) in the space between the heat insulating tube 20 and the core 10.

  The former 11 keeps the conductor layer 12 in a predetermined shape, and is also a shunt path for accident current. As described in detail later, the former 11 of the superconducting cable of the present invention has a stranded wire structure in which a plurality of strands are twisted together. The material of the former 11 is preferably a nonmagnetic metal material such as copper, stainless steel, or aluminum.

  The cushion layer provided on the former 11 can be formed by winding kraft paper on the former 11 in a spiral shape. By this cushion layer, the surface of the former 11 can be smoothed, and the conductor layer 12 can be prevented from being in direct contact with the former 11 and being damaged.

  The conductor layer 12 can be formed by winding a superconducting wire in multiple layers on a cushion layer. Each layer constituting such a conductor layer 12 is usually different in the twist pitch of the superconducting wire. In addition, the current flowing in each layer can be equalized by changing the winding direction for each layer or for each of the plurality of layers. As the superconducting wire constituting the conductor layer 12, a bismuth-based superconducting wire (for example, Bi2223-based Ag-Mn sheathed tape wire), an yttrium-based superconducting thin film (for example, YBCO-based thin film), or the like can be used.

  The insulating layer 13 can be formed by, for example, winding semi-synthetic paper (PPLP: registered trademark, manufactured by Sumitomo Electric Industries, Ltd.) laminated with kraft paper and a resin film such as polypropylene around the inner semiconductive layer.

  The internal semiconductive layer provided between the conductor layer 12 and the insulating layer 13 and the external semiconductive layer provided between the insulating layer 13 and the shield layer 14 can be formed, for example, by winding carbon paper. These internal semiconductive layer and external semiconductive layer suppress the generation of minute voids at the interface between the conductor layer 12 and the insulating layer 13 and the interface between the insulating layer 13 and the shield layer 14, respectively. Prevent partial discharge.

  Superconducting shield layer 14 provided on the external semiconductive layer can be formed by winding a superconducting wire similar to that used for conductor layer 12. The shield layer 14 is substantially the same size as the conductor layer 12 and induces a reverse current to substantially cancel the magnetic field generated from the conductor layer 12 and prevent leakage of the magnetic field to the outside. it can.

  The protective layer 15 can be formed, for example, by winding kraft paper. The protective layer 15 mechanically protects the shield layer 14 and insulates it from the heat insulating tube 20.

  On the other hand, the heat insulating tube 20 has a stainless double tube structure having a corrugated inner tube 21 and an outer tube 22. Usually, a space is formed between the inner tube 21 and the outer tube 22, and the space is evacuated. In the space to be evacuated, a super insulation serving as a heat insulating material (not shown) is arranged to reflect radiant heat. An anticorrosion layer 23 made of a resin such as polyvinyl chloride is formed outside the corrugated outer tube 22.

  In a superconducting cable having the above configuration, a distributed optical fiber temperature measurement system (DTS) in which an optical fiber for measuring the temperature of the cable is arranged inside the superconducting conductor layer 12 and the optical fiber is used as a temperature sensor. To construct. The DTS is a system that can measure a continuous temperature distribution along an optical fiber using the optical fiber as a temperature sensor. Specifically, when pulsed light is incident from one end side of the optical fiber, the Raman backscattered light reflected from each position of the optical fiber is measured on the incident side, and the reflected scattered light is analyzed by data analysis. A system that can measure the reflected position and the temperature at this position.

  Hereinafter, four embodiments having different arrangement states of optical fibers will be described with reference to FIGS. In these drawings, the same reference numerals indicate common configurations.

<Embodiment 1>
In the present embodiment, an example in which an optical fiber is arranged in a hollow portion formed in the central portion of a former formed by further collecting segments formed by collecting stranded wires will be described with reference to FIG.

  1A is a cross-sectional view of a stranded wire, FIG. 1B is a cross-sectional view of a stranded wire assembled to form a segment, and FIG. 1C is a schematic configuration diagram illustrating a state in which an optical fiber is arranged in a former including the segment. is there.

  In order to obtain the state shown in FIG. 1 (C), first, as shown in FIG. 1 (A), for example, six outer strands 2 are twisted around one central strand 1 to form a stranded wire. 3 is formed (see FIG. 1A). Each of the stranded wires 1 and 2 is individually coated with an insulation, and the wires 1 and 2 are insulated from each other.

  Next, as shown in FIG. 1 (B), for example, a segment 4 having a fan-shaped stranded wire bundle is formed by a segment forming preformer while twisting together in a state where seven stranded wires 3 are assembled. To do. The cross section of each segment has a contour surrounded by an outer circumferential arc, an inner circumferential arc, and a pair of linear portions extending in the radial direction, and the central angle of both linear portions is 60 °. That is, a fan-shaped notch is formed on the inner peripheral side of the segment. Then, as shown in FIG. 1C, after the six segments 4 are gathered and formed into a circular cross section, a binder 11 made of, for example, a stainless steel wire is spirally wound around the outer periphery thereof to form the former 11. Form. Here, FIG. 1 (C) schematically shows a cross section of the former 11. Actually, the strands 1 and 2 are pressed against each other by compression molding, and a part thereof is plastically deformed. The former 11 is in close contact with almost no gap, and the outer shape of the former 11 is almost a perfect circle.

  A hollow portion H is formed in the center of the former 11 configured in this manner by collecting fan-shaped cutouts on the inner periphery side of the segment. In the present embodiment, the optical fiber F is inserted into the position of the hollow portion H.

  The optical fiber F used is not only a bare optical fiber composed of a core and a cladding covering the outer periphery of the core, but also a primary coating (for example, urethane) and a secondary coating (for example, nylon) on the outer periphery of the optical fiber. In addition, an optical fiber cord including a tensile material (for example, aramid resin) and a jacket (for example, vinyl) on the outer periphery of the optical fiber core is also included. In the superconducting cable of the present invention, the optical fiber F may be used in a state of being housed in a metal tube such as stainless steel. The metal tube is not easily reduced in strength even at a very low temperature where a superconducting cable is used, and can protect the optical fiber from the outside.

According to the structure of Embodiment 1 demonstrated above, there exist the following effects.
[1] Since the optical fiber F is disposed in the hollow portion H originally provided in the segment structure former 11, the optical fiber F does not increase the outer diameter of the cable core.
[2] Since the hollow portion H is used for the arrangement of the optical fiber F, it is not necessary to change the configuration of the former 11 at all, and the arrangement of the optical fiber F is easy.
[3] Since the optical fiber F is protected by the former 11, even if stress is applied to the cable core from the outside of the cable core, the optical fiber F is hardly damaged.
[4] Since no irregularities are formed on the outer layer from the superconducting conductor layer in the cable core, the electrical performance of the cable core is not affected.

<Embodiment 2>
In the second embodiment, an example in which a part of the former wire is replaced with an optical fiber will be described with reference to FIG. The difference between the former 11 in the former 11 in FIG. 2 is that the cross-sectional shape of the segment 4 is a shape obtained by dividing a circle into six parts, and there is no fan-shaped notch on the inner peripheral side.

  In the former 11 of FIG. 2, one of the strands 1 or 2 constituting the former 11 having a stranded wire structure is replaced with an optical fiber F. Here, the former 11 having a twisted wire structure originally has a sufficient cross-sectional area as a shunt path for fault current. Therefore, when a part of the strands 1 and 2 of the former 11 is replaced with the optical fiber F, the shunt path is used. As a result, the function of the former 11 does not deteriorate.

  The optical fiber F may be replaced with the strands 1 and 2 at any position in the segment 4. However, since the optical fiber F may be damaged if it is arranged so as to draw a spiral at a short pitch, among the strands constituting the former 11, the strands arranged linearly or in a state close to a straight line It is preferable to replace the arranged strand with the optical fiber F. For example, if the seven-strand twisted structure in FIG. 1A is taken as an example, the central strand 1 at the center of the twist may be replaced with the optical fiber F. In consideration of heat conduction from the conductor layer, the strands 1 and 2 on the outer peripheral side of the former 11 may be replaced with the optical fiber F.

  According to the configuration of the present embodiment described above, since the optical fiber F is a part of the former 11, the outer diameter of the cable core does not increase and the stress acting from the outside of the cable core is not affected. The optical fiber F can be effectively protected.

<Embodiment 3>
In the third embodiment, an example in which an optical fiber is disposed in a twisted groove on the outer periphery of a former will be described with reference to FIG.

  In the former 11 of FIG. 3, the optical fiber F is arranged along the position of the twisted groove between the strands 1 and 2 formed on the outer periphery of the former 11, that is, the outer periphery of the segment 4. Since a twisted groove is always formed in the outer periphery of the former 11 having a stranded wire structure, the optical fiber F is arranged by effectively using the twisted groove. Even if the optical fiber F to be arranged does not fit in the twisted groove, the optical fiber F itself has a small diameter, and even if it is housed in a metal tube, the amount of protrusion from the twisted groove is very small. It is. In the first place, since a cushion layer formed by winding a tape material is formed on the outer periphery of the former 11, the outer diameter of the cable core is hardly increased by arranging the optical fiber F in the twisted groove.

  As another configuration of the present embodiment, when a plurality of segments 4 are assembled, a gap is formed between adjacent segments 4 on the outer periphery of the former 11 so that the optical fiber F is disposed in the gap. To do. In addition, the said clearance gap is synonymous with the twist groove | channel formed with an adjacent strand.

  According to the configuration of the present embodiment described above, since the optical fiber F is disposed in the twist groove of the former 11, the optical fiber F can be disposed without increasing the outer diameter of the separate cable core. Moreover, according to this structure, since it is only necessary to arrange | position the optical fiber F with respect to the former 11 of a conventional structure, productivity is good.

<Embodiment 4>
This embodiment demonstrates the example which has arrange | positioned the optical fiber along the tape material which comprises a cushion layer in the outer periphery of a former | foamer based on FIG.

  In the superconducting cable of FIG. 4, the optical fiber F is disposed along the tape material CT constituting the cushion layer formed on the surface of the former 11. The cushion layer is provided for the purpose of smoothing the outer peripheral surface of the former 11, and is usually formed by winding the tape material CT in a plurality of layers. Due to such a configuration, various configurations as exemplified below can be selected as the arrangement state of the optical fiber F.

  The tape material CT of FIG. 4 is wound with a gap. Gap winding is a winding method in which a gap is provided between a turn and a turn adjacent to the turn. In this case, the optical fiber F is spirally wound along the tape material CT between adjacent turns of the tape material CT to be gap-wrapped. The arranged optical fiber F may be pressed from the outer peripheral side by the tape material CT that is the next layer of the tape material CT along with the optical fiber F. Also, when the tape material CT is wound with the side edge of a turn and the side edge of a turn adjacent to the turn abutted (butting winding), or between a turn and a turn adjacent to the turn When the tape material CT is wound in a state of being partially overlapped (overlapping), after the optical fiber F is placed along the tape material CT that has been wound first, the tape material CT is pressed from the outer periphery of the optical fiber F. You can do it.

  In addition, a groove may be cut in the cushion layer, and the optical fiber F may be disposed in the groove. For example, first, a groove is cut in a temporary cushion layer formed by winding the tape material CT around the former 11, and the optical fiber F is disposed in the groove. And if the optical fiber F is arrange | positioned, tape material CT may be wound further on a temporary cushion layer, and a cushion layer should just be completed. At that time, the groove is formed along the tape material CT so as not to cut the tape material CT.

  According to the configuration of the present embodiment described above, since the optical fiber F is arranged in the cushion layer originally provided in the cable core, it is difficult to damage the optical fiber F without increasing the outer diameter of the separate cable core. Can be placed in position. In addition, since the cushion layer is smoothed by winding the tape material CT, irregularities are not formed on the outer layer than the superconducting conductor layer, and the electrical performance of the cable core is not deteriorated.

  In addition, this invention is not necessarily limited to said embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.

  The superconducting cable of the present invention can be suitably used as a component part of a superconducting cable line having a function of measuring the temperature during operation.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of the former of the superconducting cable which concerns on Embodiment 1, Comprising: (A) is a cross section of a strand wire, (B) is the state which collects a plurality of strand wires, and forms a segment, (C) is The state which has arrange | positioned the optical fiber in the hollow part formed in the twist center of the segment in a former is shown. It is a schematic block diagram of the former of the superconducting cable which concerns on Embodiment 2, Comprising: The state which substituted some strands in the segment by the optical fiber is shown. It is a schematic block diagram of the former of the superconducting cable which concerns on Embodiment 3, Comprising: The state which has arrange | positioned the optical fiber along the twist groove | channel between the strands in a segment is shown. It is a schematic block diagram of the former of the superconducting cable which concerns on Embodiment 4, Comprising: The state which has arrange | positioned the optical fiber along the tape material which comprises the cushion layer formed in a former outer periphery is shown. It is a cross-sectional view of a superconducting cable.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Superconducting cable 10 Cable core 11 Former 12 Superconducting conductor layer 13 Insulating layer 14 Superconducting shield layer 15 Protective layer 20 Thermal insulation tube 21 Inner tube 22 Outer tube 23 Corrosion-proof layer 1 Central strand 2 Outer strand 3 Stranded wire 4 Segment F Optical fiber H Hollow part B Binder CT Tape material

Claims (6)

A superconducting cable comprising an optical fiber, a former, and a superconducting conductor layer disposed on the outer periphery of the former,
The former is a stranded wire structure formed by twisting a plurality of strands,
The superconducting cable, wherein the optical fiber is combined with the former so that the temperature of the superconducting cable can be measured over the entire length inside the superconducting conductor layer. The former is formed by assembling a plurality of fan-shaped segments formed by twisting a plurality of strands so that a hollow portion is formed at the center of the former,
The superconducting cable according to claim 1, wherein the optical fiber is inserted into the hollow portion.   The superconducting cable according to claim 1, wherein some of the strands constituting the former are replaced with optical fibers.   The superconducting cable according to claim 1, wherein an optical fiber is disposed along a twisted groove between the strands in the outer peripheral portion of the former. A cushion layer formed by winding a tape material between the former and the superconducting conductor layer,
The superconducting cable according to claim 1, wherein an optical fiber is disposed along the tape material.   The superconducting cable according to claim 1, wherein the optical fiber is disposed in a state of being housed in a metal tube that protects the optical fiber.

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