JP2004199940A - Superconducting cable device - Google Patents

Abstract

An object of the present invention is to obtain a superconducting cable device capable of improving current-carrying efficiency as a whole.
A coolant flows in a cable tube, and three superconducting conductors are arranged in the cable tube. Each superconducting conductor 1 is energized in a superconducting state by cooling the refrigerant. The superconducting conductor 1 has first to third unit conductors connected sequentially along the cable tube 14. The cross-sectional area of the first unit conductor disposed on the upstream side of the refrigerant is smaller than the cross-sectional area of the third unit conductor disposed on the downstream side.
[Selection] Fig. 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting cable device in which a refrigerant for cooling a superconducting conductor flows through a cable tube containing the superconducting conductor.
[0002]
[Prior art]
In a conventional three-phase collective superconducting cable device, three superconducting conductors are arranged in one cable tube. Each superconducting conductor is cooled by a refrigerant flowing in the cable tube. Further, the cross-sectional area of the superconducting conductor is the same at any point (for example, see Non-Patent Document 1).
[0003]
[Non-patent document 1]
Shoichi Honjo and Yoshihisa Takahashi, "Summary of 100m superconducting cable practicality verification test", "Low temperature engineering", May 25, 2001, Vol. 36 No. 5 2001, p. 242-248
[0004]
[Problems to be solved by the invention]
In the conventional superconducting cable device as described above, since the refrigerant absorbs heat in the cable tube, the temperature of the refrigerant is higher at the refrigerant outlet side than at the refrigerant inlet side of the cable tube. Further, the critical current value of the superconducting conductor becomes smaller as the temperature becomes higher, and therefore becomes minimum at the refrigerant outlet side. From this, the maximum allowable current value of the superconducting conductor is determined based on the critical current value on the refrigerant outlet side. That is, the allowable maximum energizing current value of the superconducting conductor is suppressed to a low value by the critical current value on the refrigerant outlet side, although there is a margin in the energizing capability of the superconducting conductor on the refrigerant inlet side.
[0005]
As described above, in the conventional superconducting cable device, the current-carrying capacity of the superconducting conductor on the refrigerant inlet side cannot be effectively utilized. That is, the difference in the energizing capability of the superconducting conductors on the refrigerant inlet side and the refrigerant outlet side hinders improvement in energizing efficiency of the entire superconducting cable device.
[0006]
Therefore, an object of the present invention is to solve the above-described problems, and an object of the present invention is to provide a superconducting cable device that can improve the power supply efficiency as a whole.
[0007]
[Means for Solving the Problems]
A superconducting cable device according to the present invention includes a cable pipe through which a refrigerant flows, and a superconducting conductor arranged in the cable pipe and having a smaller cross-sectional area on the upstream side than on the downstream side of the flow of the refrigerant.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a configuration diagram schematically showing a superconducting cable device according to Embodiment 1 of the present invention. In the figure, superconducting conductor 1 is arranged in cooling pipe 2. One end of superconducting conductor 1 is connected to power transmitting side power converter 3, and the other end is connected to power receiving side power converter 4. As a result, the power from the power transmitting side power converter 3 is transmitted to the power receiving side power converter 4 via the superconducting conductor 1. In the cooling pipe 2, a coolant flows from the power transmission side power converter 3 side to the power reception side power converter 4 side in order to cool the superconducting conductor 1. The refrigerant is cooled in the cooling station 5. As the refrigerant, for example, supercooled liquid nitrogen is used.
[0009]
The cooling station 5 includes a refrigerator 6 for cooling the refrigerant, a refrigerant tank 7 for storing the refrigerant cooled by the refrigerator 6, a liquid sending pump 8 for supplying the refrigerant stored in the refrigerant tank 7 into the cooling pipe 2, have. The coolant from the cooling station 5 is sent to the coolant inlet 2 a of the cooling pipe 2 by the liquid sending pump 8 and flows through the cooling pipe 2, and then returned to the cooling station 5 from the coolant outlet 2 b of the cooling pipe 2. That is, the refrigerant is circulated between the cooling station 5 and the inside of the cooling pipe 2 by the power of the liquid sending pump 8.
[0010]
The cooling pipe 2 has three unit pipe parts 9, 10, 11 arranged along the superconducting conductor 1. Relay units 12 and 13 for connecting the unit pipe sections 9, 10, and 11 are arranged between the unit pipe sections 9, 10, and 11, respectively.
[0011]
2 is a sectional view taken along line II-II in FIG. 1, FIG. 3 is a sectional view taken along line III-III in FIG. 1, and FIG. 4 is a sectional view taken along line IV-IV in FIG. It is. In the figure, unit pipe sections 9, 10, and 11 have cylindrical cable pipe sections 14a, 14b, and 14c in which three superconducting conductors 1 are arranged, and cable pipe sections 14a, It has a cylindrical outer tube portion 16a, 16b, 16c surrounding 14b, 14c.
The cable tube 14 has cable tube portions 14a, 14b, and 14c. The protective outer tube 16 has outer tube portions 16a, 16b, 16c. Each superconducting conductor 1 is covered with an electric insulator 17 to prevent a short circuit. Further, the inner diameters of the cable pipe portions 14a, 14b, 14c are the same, and the inner diameters of the outer pipe portions 16a, 16b, 16c are also the same.
[0012]
The refrigerant flows through the cable tube 14. That is, the refrigerant flows through the refrigerant passage 18 between the inner wall surface of the cable tube 14 and the superconducting conductor 1 covered with the electric insulator 17. Each superconducting conductor 1 is cooled by the refrigerant, and the superconducting state is maintained.
[0013]
Each superconducting conductor 1 has first to third unit conductors 19, 20, 21 which are sequentially connected from the refrigerant inlet 2a side (FIG. 1) to the refrigerant outlet 2b side (FIG. 1). Further, the first to third unit conductor portions 19, 20, 21 are arranged in the unit tube portions 9, 10, 11 respectively, and are connected at the same positions as the positions of the relay portions 12, 13 (FIG. 1). .
[0014]
The cross-sectional area of the first unit conductor section 19 is smaller than the cross-sectional area of the second unit conductor section 20, and the cross-sectional area of the second unit conductor section 20 is smaller than the cross-sectional area of the third unit conductor section 21. . That is, the cross-sectional area of the superconducting conductor 1 is smaller on the upstream side than on the downstream side of the refrigerant. For this reason, the cross-sectional area of the refrigerant passage 18 is larger on the upstream side than on the downstream side of the refrigerant.
The superconducting conductor 1 is a Bi2223 wire.
[0015]
FIG. 5 is a graph showing the relationship between the critical current ratio of the superconducting conductor of Bi2223 wire and the cooling temperature. The critical current value ratio is a ratio between a critical current value at a cooling temperature of 77 K and a critical current value at each cooling temperature. As shown in FIG. 5, the critical current value at the cooling temperature 65K is about 1.5 times the critical current value at the cooling temperature 77K. This indicates that the superconducting conductor 1 can flow about 1.5 times the current in the superconducting state by reducing the cooling temperature of the superconducting conductor 1 from 77K to 65K. That is, the superconducting conductor 1 can flow more current as the cooling temperature is lower.
[0016]
Since the temperature of the refrigerant for cooling the superconducting conductor 1 gradually increases from the refrigerant inlet 2a side toward the refrigerant outlet 2b side, the critical current value of the superconducting conductor 1 gradually decreases along the refrigerant flowing direction. Become. On the other hand, since the cross-sectional area of the superconducting conductor 1 is gradually increased from the refrigerant inlet 2a side toward the refrigerant outlet 2b side, the current that can be passed through the superconducting conductor 1 gradually increases along the flowing direction of the refrigerant. Become larger. Therefore, by adjusting the balance between the cross-sectional area of the superconducting conductor 1 and the temperature of the refrigerant, the allowable maximum energizing current value of the superconducting conductor 1 can be determined for each part.
[0017]
The cross-sectional area of superconducting conductor 1 in the first embodiment is smaller on the refrigerant inlet 2a side than on the refrigerant outlet 2b side so that the permissible maximum energizing current value is almost the same at any point. Here, the cross-sectional area of the first unit conductor section 19 is about 70% of the cross-sectional area of the third unit conductor section 21, and the cross-sectional area of the second unit conductor section 20 is Of about 85% of the cross-sectional area of.
[0018]
In the superconducting cable device having such a configuration, since the cross-sectional area of the superconducting conductor 1 is made smaller on the upstream side than on the downstream side of the refrigerant, the current-carrying capacity of the superconducting conductor 1 which has been wasted conventionally can be cut. In addition, the imbalance in the magnitude of the allowable maximum energizing current value in the superconducting conductor 1 can be reduced. From this, it is possible to improve the energizing efficiency of the entire superconducting cable device.
[0019]
Further, since the cross-sectional area of superconducting conductor 1 is reduced on the upstream side of the refrigerant, the material of superconducting conductor 1 is reduced by that much, and the cost can be reduced.
[0020]
Also, by reducing the cross-sectional area of superconducting conductor 1 on the upstream side of the refrigerant, the cross-sectional area of refrigerant passage 18 can be increased on the upstream side, and the pressure loss of the refrigerant can be reduced. Thereby, the power of the liquid sending pump 6 can be reduced, and the equipment cost can be reduced. Furthermore, when a plurality of cooling stations 5 are installed, the transfer distance of the refrigerant can be lengthened, so that the number of installed cooling stations 5 can be reduced, and the equipment cost can be further reduced.
[0021]
Moreover, since the superconducting conductor 1 has the first to third unit conductor portions 19, 20, and 21 connected to each other along the length direction, the superconducting conductor 1 can be easily manufactured over a long distance. can do.
[0022]
In the above example, the cross-sectional area of the superconducting conductor 1 decreases stepwise from the refrigerant outlet 2b side toward the refrigerant inlet 2a side, but continuously decreases according to the temperature gradient of the refrigerant. Is also good. That is, the cross-sectional diameter of superconducting conductor 1 may be changed into a tapered shape. By doing so, it is possible to further reduce the imbalance in the magnitude of the allowable maximum energizing current value in superconducting conductor 1.
[0023]
Further, in the above example, the superconducting conductor 1 has the first to third unit conductor portions 19, 20, and 21 connected to each other, but the diameter of one superconducting conductor 1 is increased along the length direction. It may be changed stepwise.
[0024]
Further, in the above example, the connecting portions of the first to third unit conductor portions 19, 20, 21 are at the same positions as the positions of the relay portions 12, 13, but are not limited to this position. It can be anywhere inside.
Furthermore, in the above example, the cooling pipe 2 is divided into three unit pipe sections 9, 10, and 11, but the number of divisions is not limited to three and may not be divided.
[0025]
Embodiment 2 FIG.
FIG. 6 is a configuration diagram schematically showing a superconducting cable device according to Embodiment 2 of the present invention. In the figure, a cooling pipe 2 has unit pipe portions 25, 26, 27 sequentially arranged from the refrigerant inlet 2a side to the refrigerant outlet 2b side along the superconducting conductor 1. The unit pipe sections 25, 26, 27 are connected to each other by relay sections 28, 29.
[0026]
As in the first embodiment, the unit pipe sections 25, 26, and 27 have a cylindrical cable pipe section and a cylindrical outer pipe section surrounding the cable pipe section via a heat insulating layer. However, the outer diameters of the unit pipe portions 25, 26, and 27 are different from each other. That is, the outer diameter D1 of the unit tube 25 is smaller than the outer diameter D2 of the unit tube 26, and the outer diameter D2 of the unit tube 26 is smaller than the outer diameter D3 of the unit tube 27. The inner diameter of each cable tube is set so that the cross-sectional area of the refrigerant passage 18 (see FIGS. 2 to 4) is the same or substantially the same. Other configurations are the same as in the first embodiment.
[0027]
In the superconducting cable device having such a configuration, since the outer diameter of the cooling pipe 2 is smaller at the refrigerant inlet 2a side than at the refrigerant outlet 2b side, the cooling pipe 2 is moved from the refrigerant outlet 2b side in a limited space. Many can also be arranged on the refrigerant inlet 2a side. Therefore, for example, a large number of cooling pipes 2 on the power transmission side power converter 3 side can be accommodated in a power cable pipeline buried underground, and the number of power supply systems can be increased. Here, since the outer diameter of the cooling pipe 2 on the power receiving side power converter 4 side is larger than that on the power transmitting side power converter 3 side, it is not possible to increase the number of power supply systems. Since the power supply 4 is usually installed at a different place and the power cable pipeline is branched in the middle, the number of power supply systems at the end of the power cable pipeline is smaller than that of the power transmission side power converter 3 side, and The cooling pipe 2 can be stored in the power cable conduit without any problem on the side power converter 4 side.
[0028]
In the above example, the cooling pipe 2 is gradually reduced from the refrigerant outlet 2b side toward the refrigerant inlet 2a side, but is continuously reduced according to the diameter of the superconducting conductor 1 arranged inside. It may be.
[0029]
【The invention's effect】
As is apparent from the above description, the superconducting cable device according to the present invention is arranged in the cable pipe through which the refrigerant flows, and in the cable pipe, and has a smaller cross-sectional area on the upstream side than on the downstream side of the flow of the refrigerant. Since the superconducting conductor is provided, the imbalance in the magnitude of the allowable maximum conducting current value in the superconducting conductor can be reduced, and the energizing efficiency as a whole can be improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram schematically showing a superconducting cable device according to a first embodiment of the present invention.
FIG. 2 is a sectional view taken along the line II-II of FIG.
FIG. 3 is a sectional view taken along line III-III in FIG.
FIG. 4 is a sectional view taken along the line IV-IV in FIG. 1;
FIG. 5 is a graph showing a relationship between a critical current value ratio of a superconducting conductor of Bi2223 wire and a cooling temperature.
FIG. 6 is a configuration diagram schematically showing a superconducting cable device according to a second embodiment of the present invention.
[Explanation of symbols]
1 superconducting conductor, 14 cable tube, 19, 20, 21 first to third unit conductors (conductors).

Claims (3)

A superconducting cable device, comprising: a cable tube through which a refrigerant flows, and a superconducting conductor disposed in the cable tube and having a smaller cross-sectional area on the upstream side than on the downstream side of the flow of the refrigerant. . The superconducting conductor has a plurality of unit conductors connected to each other along its length,
2. The superconducting cable device according to claim 1, wherein a sectional area of the unit conductor located on the upstream side is smaller than a sectional area of the unit conductor located on the downstream side. 3. 3. The superconducting cable device according to claim 1, wherein an outer diameter of the cable tube is smaller on the upstream side than on the downstream side.

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