JP2007258192A - Intermediate connection of superconducting cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intermediate connection portion of a superconducting cable that can be miniaturized. [MEANS FOR SOLVING PROBLEMS] An intermediate connection portion of a superconducting cable that connects a superconducting cable having a former 200, a superconducting conductor 201, and an insulating layer 202. . The connecting sleeve 300 is fitted on the outer periphery of each end of the former to be abutted, and the outer diameter of the connecting sleeve 300 and the outer diameter of the former 200 are made equal by compressing and connecting the formers 200 to each other. Then, the superconducting conductors 201 abutted on the outside of the connection sleeve 300 are connected to be equal to the outer diameter of the superconducting conductor in the superconducting cable.
[Selection] Figure 1

Description

  The present invention relates to an intermediate connection portion of a superconducting cable. In particular, the present invention relates to an intermediate connection portion of a superconducting cable that can be reduced in size.

  Conventionally, in a superconducting cable with a superconducting conductor made of Bi-based high-temperature superconducting tape wire, etc., not only a single-phase cable with one cable core but also a multi-core multi-phase cable with multiple cable cores in a lump. Is being developed. FIG. 2 shows a three-core one-phase superconducting cable. The superconducting cable 100 has a configuration in which three cable cores 102 are twisted and housed in a heat insulating tube 101.

  The heat insulating tube 101 has a structure in which a heat insulating material (not shown) is disposed between the double tubes composed of the outer tube 101a and the inner tube 101b, and the inside of the double tube is evacuated. Of these, the anticorrosion layer 104 is formed on the outer tube 101a. Each cable core 102 includes a former 200, a superconducting conductor 201, an electrical insulating layer 202, a shield layer 203, and a protective layer 204 in order from the center. The superconducting conductor 201 is formed by spirally winding a superconducting wire on the former 200 in multiple layers. The electrical insulating layer 202 is configured by winding semi-synthetic insulating paper. The shield layer 203 is configured by spirally winding a superconducting wire similar to the superconducting conductor 201 on the electrical insulating layer 202. In the shield layer 203, a current of almost the same magnitude is induced in the opposite direction to the current flowing in the superconducting conductor 201 in a steady state. With the magnetic field generated by the induced current, the magnetic field generated from the superconducting conductor 201 can be canceled and the leakage magnetic field to the outside of the cable core 102 can be made almost zero. Normally, a space 103 surrounded by the inner tube 101b and each cable core 102 serves as a refrigerant flow path.

  When constructing a long-distance line using such a multiphase superconducting cable, an intermediate connection for connecting cable cores drawn from different cables is required in the middle of the line. As an intermediate connection portion of a multiphase superconducting cable, for example, there is one described in Patent Document 1. In this structure, as shown in FIG. 3, the ends of the superconducting conductor 201 housed in the connection box 500 are connected to each other by a normal conducting connecting sleeve 510 such as Cu, and the ends of the superconducting conductor 201 and the connecting sleeve 510 are connected. The stress cone 520 is attached to the outer periphery of the. The stress cone 520 is supported by a support rod 530 made of FRP, and the cable core 102 in the connection box is supported by a branch portion 540 made of FRP.

JP 2000-340274 A (Fig. 1)

  However, the above technique has the following problems.

(1) The amount of heat generated at the intermediate connection is increased.
In the above connection part, a normal conducting material is used for the connection sleeve. This part has a higher conductor resistance than the superconducting conductor, generates heat due to Joule loss at the connection part, and places a burden on the cooling system of the refrigerant. .

(2) The size of the intermediate connection portion is increased.
In the connection portion described above, since the outer diameter of the connection sleeve is larger than that of the superconducting conductor and electric field stress is generated in the layer direction, it is necessary to provide a stress cone for mitigation. This stress cone is formed by winding insulating paper, for example. Therefore, an intermediate connection part becomes large in a radial direction and a longitudinal direction. In addition, since the stress cone is formed by using a large amount of insulating paper having a high thermal resistance, the thermal resistance of the stress cone is large, coupled with the heat generation of the connection sleeve due to the Joule loss, and the intermediate connection is the largest in cooling. It can also be an obstacle.

(3) Pressure loss of the refrigerant may occur at the intermediate connection part.
In the above connection portion, a stress cone is provided, and the stress cone is supported by a support rod made of FRP. Therefore, this support rod becomes an obstacle to the circulation of the refrigerant, and as a result of causing pressure loss, the cooling capacity of the connection portion may be affected.

  Accordingly, a main object of the present invention is to provide an intermediate connection portion of a superconducting cable that can be reduced in size.

  Another object of the present invention is to provide an intermediate connection portion of a superconducting cable that can suppress the occurrence of Joule loss in the connection portion.

  The present invention achieves the above-mentioned object by connecting the superconducting conductors attached together so as to have the same diameter at the intermediate connection portion and other portions.

  The intermediate connection portion of the present invention is an intermediate connection portion of a superconducting cable that connects a superconducting cable having a former, a superconducting conductor, and an insulating layer. The connecting sleeves are fitted into the end portions of the formers to be abutted, and the formers are connected by equalizing the outer diameter of the connecting sleeve and the outer diameter of the former by compression connection. Then, the superconducting conductors butted on the outside of the connection sleeve are connected to be equal to the outer diameter of the superconducting conductor in the superconducting cable.

  Without compressing the outer diameter of this connecting sleeve to a substantially equal outer diameter with the former by compressing the conductor connection sleeve arranged on the outer periphery of the butted formers with a compressor, without increasing the diameter of the connection location Connection between formers can be performed. Therefore, the superconducting conductor located on the former can be suppressed from increasing in diameter only at the connection portion. As a result, it is not necessary to use a stress cone, and by connecting the superconducting conductors directly abutted with each other or the superconducting conductors partially overlapping each other, the size of the connecting portion, particularly the outer diameter can be reduced.

  Further, since the superconducting conductors can be directly connected to each other, it is not necessary to use a normal conducting conductor connecting sleeve, and the generation of Joule loss can be suppressed.

  Here, the connection of the former is preferably compression connection using a connection sleeve. Therefore, it is desirable that the former has a solid structure or a stranded wire structure so that compression connection is possible. For example, what twisted together the some metal wire is mentioned.

  The connection sleeve is preferably a metal sleeve that is easily plastically deformed so that compression connection is possible. Typically, a copper sleeve or the like can be used. The thickness of the sleeve is such that, for example, after compression, a cross-sectional area of 50% or more of the nominal cross-sectional area of the former can be secured. By using such a connection sleeve, when a compression connection is made such that the outer diameter of the connection sleeve substantially matches the outer diameter of the former, it is possible to easily secure the energization capacity and mechanical strength at the connection location. .

  Examples of superconducting conductors include a structure in which a superconducting wire in which a large number of Bi2223-based superconducting filaments are embedded in a matrix of silver or the like is spirally wound on a former. This superconducting wire is usually wound in multiple layers. The connection between the superconducting conductors may be performed by soldering, for example. By directly connecting the superconducting conductors without interposing the normal conducting conductor, Joule loss when using the normal conducting conductor can be avoided.

  Further, it is preferable to provide a reinforcing insulating layer on the outside of the superconducting conductor and make the outer diameter of the reinforcing insulating layer equal to the outer diameter of the insulating layer of the superconducting cable. The reinforcing insulating layer is a member that ensures electrical insulation at the intermediate connection portion. This reinforced insulating material may be formed by winding insulating paper, but there is no need to increase the thickness or form a spindle like a stress cone, and the size is greatly reduced compared to conventional connections. it can.

  The superconducting cable connected at the intermediate connection portion of the present invention may further have a shield layer. For example, a superconducting wire similar to the superconducting conductor is spirally wound or linearly disposed on the insulating layer to form the shield layer. Also in this case, the above-described reinforcing insulating layer is provided on the outer side of the superconducting conductor in the intermediate connection portion. This reinforcing insulating layer also has the same outer diameter as the insulating layer in the superconducting cable. And it is preferable to connect the shield layers abutted on the outside of the reinforcing insulating layer so as to be equal to the outer diameter of the shield layer in the superconducting cable. According to this structure, it can suppress that the outer diameter of a connection part becomes large also in the cable which has a shield layer. The shield layers may be connected to each other by, for example, soldering.

  In addition, the superconducting cable usually has a refrigerant flow path for cooling the superconducting conductor (and if the shield layer is provided, the shield layer is also cooled). The intermediate connection portion of the present invention preferably has an outer case that can ensure a cross-sectional area equivalent to the refrigerant flow path of the superconducting cable. By securing a cross-sectional area equivalent to the refrigerant flow path of the superconducting cable also in the intermediate connection part, it is possible to suppress the pressure loss of the refrigerant in the connection part. For example, the outer case may be constituted by a heat insulating case that covers the outer side of the reinforcing insulating layer in the intermediate connection portion. When the intermediate connection portion has a shield layer, a heat insulating case that covers the outside of the shield layer may be used. The outer case is preferably configured to be divided in the longitudinal direction of the superconducting cable. By making the outer case into a divided structure, it is possible to assemble the intermediate connection portion in a narrow work space.

  The intermediate connection portion of the present invention can be used not only for connection of a single-core superconducting cable but also for connection of each core of a superconducting cable in combination with three cores.

  According to the intermediate connection portion of the present invention, since the outer diameter of the former connection portion can be formed to be equal to the outer diameter of the former, the size of the intermediate connection portion can be reduced. In addition, since it is not necessary to connect the superconducting conductors via a normal conducting conductor, heat generation due to Joule loss can be suppressed.

  Embodiments of the present invention will be described below.

  Prior to the description of the intermediate connection portion of the present invention, the configuration of the superconducting cable to be connected will be described. The superconducting cable connected at the intermediate connection portion has the same configuration as the superconducting cable 100 described in FIG. That is, the three cores 102 are accommodated in the heat insulating tube 101. Each core 102 includes a former 200, a superconducting conductor 201, an insulating layer 202, a shield layer 203, and a protective layer 204 in order from the center. The former 200 is formed by twisting a plurality of copper wires into multiple layers. The superconducting conductor 201 is formed by spirally winding a superconducting wire on the former 200 in multiple layers. This superconducting wire is formed by embedding a large number of Bi2223 superconducting filaments in a silver matrix. The insulating layer 202 is formed by winding semi-synthetic paper obtained by bonding insulating paper and a polypropylene film on the superconducting conductor 201. The shield layer 203 is formed by winding a superconducting wire similar to that used for the superconducting conductor 201 on the insulating layer 202 in multiple layers.

  Next, FIG. 1 shows an intermediate connection portion for connecting the superconducting cables 100 to each other. When connecting such superconducting cables, each core is exposed for a certain length from the end of the heat insulating tube, and the length of each layer is adjusted at the end of the core. Specifically, the former 200, the superconducting conductor 201, and the shield layer 203 are set to the length to the cut end, and the insulating layer 202 is removed from the cut end by a certain length. In order to remove the insulating layer 202, the end portion of the shield layer 203 formed by winding the superconducting wire is temporarily loosened and spread to expose the insulating layer 202. In that state, the insulating layer 202 for a certain length is removed. The length to be removed is set to a length that can sufficiently compress the connecting sleeve 300 with respect to the former 200 described later. In addition, although not shown, only the former may be exposed for a certain length by cutting the superconducting conductor, the insulating layer, and the shield layer by a certain length from the end of the superconducting cable. In this case, in order to connect the superconducting conductors and the shield layers, a connecting superconducting wire is interposed separately.

  For connection between a pair of superconducting cables, first, halves 311 and 312 of the outer case 310 to be described later are fitted into the end of the three-core core assembly, and the outer case 310 is temporarily released to a position away from the end of the core. deep. In FIG. 1, only one core is shown.

  Next, after compression, a connection sleeve 300 having a thickness capable of ensuring a cross-sectional area of 50% or more of the nominal cross-sectional area of the former 200 is prepared, and the former 200 is inserted from each end of the sleeve 300. Here, a sleeve 300 made of a tough pitch copper rod (1100BD) and having an inner diameter slightly larger than the outer diameter of the former was used. In this state, the connecting sleeve 300 is compressed to connect the formers 200 to each other. By this connection, the sleeve bites into the former, and the outer diameter of the connection sleeve 300 after compression becomes substantially equal to the outer diameter of the former other than the compressed portion.

  Subsequently, the superconducting conductor 201 is connected on the connected former 200 by soldering. Since no step is formed between the surface of the connecting sleeve and the former surface, the superconducting conductor 201 itself can be obtained by rewinding the superconducting wire that has been loosened and opening it or preparing another connecting superconducting wire and connecting it. It can be avoided that the outer diameter is different between the position covering the connection sleeve 300 and other portions. In addition, it is not necessary to connect the superconducting conductor via a normal conducting material, and heat generation due to Joule loss at the connecting portion can be suppressed.

  Next, a reinforcing insulating layer 320 is formed on the connected superconducting conductor 201. Of the cores of the superconducting cable, the insulating layer 202 is removed from the end by a certain length. Therefore, the insulating insulating layer 320 may be formed by winding, for example, insulating paper around the removed portion. The outer diameter of the reinforcing insulating layer 320 is also matched with the outer diameter of the core insulating layer 202. Since the superconducting conductor or the portion electrically connected to this conductor is not partially expanded and connected in the radial direction, there is no need to form a stress cone, and the reinforcing insulation having the same thickness as the insulating layer 202 of the core The layer 320 can also provide the necessary electrical insulation.

  Next, the superconducting wire once loosened and opened is rewound on the reinforcing insulating layer 320 or another connecting superconducting wire is prepared and covered with the shield layer 203. Then, the superconducting wires constituting the shield layer and the superconducting wires for connection are connected by welding. By connecting the shield layer 203, it is possible to prevent the shield layer 203 itself from having a different outer diameter at a position where it covers the reinforcing insulating layer 320 and other locations. If the layers of the core are connected as described above, the outer diameter of the connecting portion can be made equal to the outer diameter of the core of the superconducting cable, and the size of the connecting portion can be made as small as possible.

  Further, the outer case halves 311 and 312 that have once escaped in the direction away from the end of the core are pulled back and connected to the outside of the position where the reinforcing insulating layer 320 is formed. The half bodies 311 and 312 are cylindrical bodies having a heat insulating structure with one end having a small diameter and the other end having a large diameter. The large-diameter side openings of the half bodies 311 and 312 are brought into contact with each other and integrated by welding or fastening with a bolt using a flange. By joining the halves 311 and 312, an outer case 310 having both ends with a small diameter and an intermediate portion with a large diameter is formed. Although not shown in FIG. 1, both ends of the outer case 310 are connected to the ends of the heat insulating tube 101 (FIG. 2) of the superconducting cable.

  The inner diameter of the small-diameter portion of the outer case 310 is ensured to be equal to or larger than the inner diameter of the heat insulating tube of the superconducting cable. Since the space between the inner side of the outer case 310 and the outer side of the shield layer serves as a refrigerant flow path, securing the inner diameter of the outer case 310 can ensure a refrigerant flow path cross-sectional area equivalent to that in the superconducting cable, and The pressure loss of the refrigerant can be suppressed.

  The intermediate connection part of the present invention is expected to be used as a connection point between superconducting cables in a superconducting cable line used for a power transportation path or the like.

It is a fragmentary longitudinal cross-sectional view of this invention intermediate connection part. (A) is sectional drawing of the superconducting cable connected by this invention connection part, (B) is a perspective view which shows the stepped state of the cable core. It is a fragmentary sectional view of the conventional intermediate connection part.

Explanation of symbols

100 Three-phase superconducting cable 101 Insulated tube 101a Outer tube 101b Inner tube
102 Cable core 103 Space 104 Anticorrosion layer
200 Former 201 Superconducting conductor 202 Insulating layer 203 Shield layer
204 Protective layer
300 Connection sleeve 310 Outer case 311, 312 Half 320 Reinforcing insulation layer
500 Connection box 510 Normal conductive connection sleeve 520 Stress cone
530 Support bar 540 Branch

Claims (4)

An intermediate connection portion of a superconducting cable for connecting a superconducting cable having a former, a superconducting conductor, and an insulating layer,
Attach the connecting sleeve to the end of each former to be abutted, and connect the formers so that the outer diameter of the connecting sleeve is equal to the outer diameter of the former by compression connection.
An intermediate connection portion of a superconducting cable, characterized in that superconducting conductors butted on the outside of the connection sleeve are connected to be equal to the outer diameter of the superconducting conductor in the superconducting cable.   The intermediate connection portion of a superconducting cable according to claim 1, wherein a reinforcing insulating layer is provided outside the superconducting conductor, and an outer diameter of the reinforcing insulating layer is made equal to an outer diameter of the insulating layer of the superconducting cable. The superconducting cable has a shield layer,
The intermediate connection part of the superconducting cable according to claim 2, wherein the shield layers that are abutted on the outside of the reinforcing insulating layer are connected to be equal to the outer diameter of the shield layer in the superconducting cable. The superconducting cable has a refrigerant flow path for cooling the superconducting conductor;
The intermediate connection part of a superconducting cable according to any one of claims 1 to 3, wherein the intermediate connection part has an outer case capable of securing a cross-sectional area equivalent to the refrigerant flow path of the superconducting cable.

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