JP4550699B2 - Superconducting power cable termination connection - Google Patents

Description

  The present invention relates to a terminal connection portion of a superconducting power transmission cable cooled by a cryogenic liquid such as liquid nitrogen.

The terminal connection portion of the superconducting power transmission cable includes a lead conductor having one end connected directly to the conductor of the superconducting power transmission cable or indirectly through another connecting member and the other end drawn into the atmosphere.
This lead conductor is generally made of a conductor having an insulation coating in a part of its longitudinal direction, and one end side where the insulation coating is applied is cooled with liquid nitrogen or the like, and the other end where the conductor is exposed. The side is pulled out into the atmosphere.
Therefore, the lead conductor has a very large temperature gradient from the temperature of liquid nitrogen, that is, from a very low temperature to a normal temperature, in the longitudinal direction (axial direction).

The termination | terminus connection part of the general superconducting power transmission cable of patent document 1 is demonstrated using FIG.
FIG. 3 is a longitudinal sectional view showing an example of a terminal connection portion of a conventional general superconducting power transmission cable.
As shown in FIG. 3, the conductor 1 of the superconducting power transmission cable laid in the horizontal direction in the figure (hereinafter simply referred to as the superconducting conductor 1) is drawn out from the cryogenic temperature to the ambient temperature through the connecting conductor 2. The connecting member 20 is connected to the lower end of the drawn conductor 3 to be connected.
The lead conductor 3 passes through a temperature gradient portion 12 constituted by a liquid refrigerant layer 4 such as liquid nitrogen and a refrigerant gas layer 5 made of nitrogen gas or the like connected to the upper portion of the liquid refrigerant layer 4, and further this temperature gradient. After passing through the high voltage lead-out portion 13 provided above the portion 12 and partitioned by the temperature inclined portion 12 and the flange 6, the tip end portion is led to the outside.

The temperature inclined portion 12 is covered with an external pressure vessel 21 made of SUS that mainly forms a vacuum heat insulating layer as shown in FIG. Similarly, it is composed of an internal pressure vessel 22 made of SUS and the liquid refrigerant layer 4 and the refrigerant gas layer 5 described above formed in the internal pressure vessel 22.
The high voltage lead-out part 13 is mainly composed of an insulator 7, a fluid insulator 8 made of insulating oil or SF ₆ gas filled in the insulator 7, and an upper metal fitting 14 provided at the tip of the high voltage lead-out part 13. It is comprised by.

  By the way, the lead conductor 3 is provided with an insulating coating 10 made of, for example, epoxy resin or ethylene propylene rubber, over a portion located in the temperature gradient portion 12 and a portion located in the lower portion of the high voltage lead portion 13. There are many cases. Then, a bare conductor is exposed at a portion above the upper end of the insulating coating 10, and as described above, the bare conductor extends above the temperature gradient portion 12 and passes through the high voltage lead-out portion 13 to the outside. Pulled out. Reference numeral 11 denotes an electric field control member provided in the vicinity of both end portions of the insulating coating 10, that is, a stress cone. Further, the insulating coating 10 may be formed integrally with the flange 6.

Reference numeral 23 indicates a pressure bulkhead that partitions the temperature inclined portion 12 and the superconducting power transmission cable line side including the superconducting conductor 1 (not shown in detail).
Since the terminal connection part of such a superconducting power transmission cable is exposed to a very large temperature gradient from extremely low temperature to room temperature, it has the following thermal problems.

That is, in order to continue taking out the current of the superconducting power transmission cable, the superconducting power transmission cable unit must be maintained in an environment that keeps maintaining the superconducting state. Therefore, for example, it is necessary to use liquid helium or liquid nitrogen as a cooling medium and control the temperature below the boiling point thereof.
In addition, since the substation equipment and the like are at room temperature, the temperature of the cooling medium, that is, the temperature gradient portion from the extremely low temperature to the room temperature is required for the terminal connection portion of the superconducting power transmission cable described above. In this temperature gradient portion, a conductor component that allows electric current to pass while maintaining electrical insulation, specifically, the above-described lead conductor 3 is necessary. In this lead conductor 3, for example, the cooling medium is liquid nitrogen. If present, a temperature gradient from -196 ° C. to room temperature, for example, 20 ° C. occurs.

In general, in order to maintain the insulation of the lead conductor 3 described above, a polymer material such as epoxy resin, polyethylene, rubber or the like must be used as the insulating coating 10.
However, a polymer material generally has a large coefficient of thermal expansion, and a metal conductor such as a copper conductor penetrates through the central portion of the insulating coating 10 formed of the polymer material as shown in FIG. Due to the difference between the thermal expansion coefficients of the metal and the metal, a considerably large internal stress is generated in the insulating coating 10 made of the polymer material.

  On the other hand, when the terminal connection portion of the superconducting power transmission cable is assembled at room temperature and then laid as shown in FIG. 3, it is gradually cooled to the cooling medium temperature. In the cooling process, the superconducting conductor 1 is thermally contracted. At this time, as shown in FIG. 3, the connecting conductor 2 connected in a straight line with the superconducting conductor 1 and the connecting member 20 which is a connecting portion between the connecting conductor 2 and the lead conductor 3 are drawn out. The end of the conductor 3 is pulled toward the superconducting conductor 1, and as a result, bending stress is applied to the lead conductor 3.

When bending stress is applied to the lead conductor 3 in this way, the bending stress is inevitably applied to the insulating coating 10 of the lead conductor 3.
The insulating coating 10 made of a polymer material is cooled at the temperature of the cooling medium and has a reduced elastic modulus and elongation characteristics. Further, as described above, the inner coating due to the difference in thermal expansion coefficient with the metal conductor at the center of the lead conductor 3 Since stress is also generated, the insulation coating 10 is broken only when a slight force is applied.
Under such circumstances, when the bending stress described above acts, there is a high risk that the insulation coating will be broken.

  On the other hand, on the room temperature side of the lead conductor 3, Joule heat is generated during energization, and the conductor temperature of the lead conductor 3 rises due to the Joule heat. When the conductor temperature rises, the lead conductor 3 expands thermally, and a very large force acts in the axial direction of the conductor. As a result, not only the lead conductor 3, but also the portion holding the lead conductor 3, that is, the portion holding the lead conductor 3 substantially vertically, in particular, the flange 6 is formed integrally with the insulating coating 10 of the lead conductor 3. In such a case, an excessive force is applied to the portion of the flange 6 that holds the lead conductor 3 in a vertical state, and in the worst case, the holding portion, that is, the portion of the flange 6 may be broken. .

  Therefore, the above-described bending stress applied to the lead conductor 3 due to the thermal contraction of the superconducting conductor 1 is alleviated, and from the viewpoint of preventing the insulation coating 10 from being destroyed due to this bending stress, or also from the heat of the lead conductor 3. In order to make it difficult to break the holding portion due to expansion, for example, as described in Patent Document 1, there is an attempt to form the connection member 20 with a so-called flexible conductor such as a flexible lead wire. Already known.

JP-A-11-73824

  In the terminal connection part of the superconducting power transmission cable described in Patent Document 1, the superconducting conductor 1, or the connecting conductor 2 connected in a straight line to the end of the superconducting conductor 1, the superconducting conductor 1 and the connecting part are connected. The central axis of the conductor 2 and the ends of the lead conductor 3 whose central axis is orthogonal to each other are connected by a flexible conductor such as a lead wire.

If the connecting member 20 is formed of a flexible conductor in this way, the bending stress applied to the lead conductor 3 due to the thermal contraction of the superconducting conductor 1 and the stress applied to the holding part due to the thermal expansion of the lead conductor 3 are also sure. , Some of them may be surely mitigated.
However, as described above, the insulating coating 10 made of a polymer material has already been cooled at the temperature of the cooling medium and has decreased elastic modulus and elongation characteristics, and the difference in thermal expansion coefficient from the metal conductor located at the center. Because it also has internal stress due to, it is in a state where it is not strange that even a slight external force causes destruction.

  From such a point of view, the insulation coating 10 can still be obtained simply by connecting the end of the superconducting conductor 1 or the connecting conductor 2 linearly connected thereto and the lower end of the lead conductor 3 with a flexible conductor. It is hard to say that it is enough to prevent the destruction of the. Further, it is difficult to say that the portion holding the lead conductor 3 can be completely prevented from being broken.

  Accordingly, an object of the present invention is to generate a stress load due to thermal contraction of the superconducting conductor during the cooling process even if the insulating coating made of the polymer material at the lower end of the lead conductor is continuously used in a state cooled to the cooling medium temperature. However, breakage of the insulation of the lead conductor is less likely to occur, and the action of the stress generated by the thermal expansion of the lead conductor during energization causes the insulation of the lead conductor to break and keep this lead conductor almost vertical. It is an object of the present invention to provide a terminal connection portion of a superconducting power transmission cable that can reduce the risk of breakage of the holding portion.

  In order to achieve the above object, the terminal connection part of the superconducting power transmission cable according to claim 1 is provided at at least one end of the superconducting power transmission cable that transmits power in a superconducting state, and takes out the current flowing in the superconducting conductor into the ambient air. A terminal connection part of a superconducting power transmission cable, comprising a lead conductor that is drawn from a cryogenic temperature to room temperature via a temperature slope part and a high voltage lead part provided above the temperature slope part, the lead conductor Is provided with an insulation coating over a portion located in the temperature gradient portion and a portion located in the lower portion of the high voltage lead-out portion, and a bare conductor portion extending above the portion provided with the insulation coating has a conductor. A slidable connecting portion having slidability in the axial direction is provided, and a lower end of the lead conductor is electrically connected to a terminal portion of the superconducting power transmission cable substantially orthogonal to the lead conductor. The flexible conductor is connected is characterized in.

  According to the terminal connection portion of the superconducting power transmission cable according to claim 1, the terminal portion of the superconducting conductor is formed directly or at the end portion of the superconducting conductor, for example, constituting the terminal portion of the superconducting conductor. A drawer that is connected to the lower end of the lead conductor that is indirectly connected via a connecting conductor etc. that is connected in a straight line by a flexible conductor, and that is positioned almost vertically in the temperature gradient part or high voltage lead part By providing a slidable connection part that has slidability in the conductor axis direction on the bare conductor part that extends above the part where the insulation coating is applied to the conductor, the heat conduction of the superconducting conductor is mainly reduced during the cooling process. The accompanying stress is absorbed and relaxed by the flexible conductor, and the stress generated by the thermal expansion of the lead conductor during energization is absorbed mainly by the slidable connection portion and relaxed.

As a result, it is difficult to apply a bending stress to the lead conductor, and the stress load on the holding portion of the lead conductor is further alleviated.
Therefore, even if the polymer material insulation coating at the lower end of the lead conductor continues to be used in a state cooled to the cooling medium temperature, or even if a stress load is generated due to thermal contraction of the superconducting conductor in the cooling process, The breakage of the insulation coating of the lead conductor can be made less likely to occur.
At the same time, it is possible to further reduce the risk of damage to the insulation of the lead conductor and the holding part of this lead conductor that may occur due to the thermal expansion of the lead conductor when energized. Department can be provided.

  As described above, according to the terminal connecting portion of the superconducting power transmission cable of the present invention, the insulating covering made of the polymer material at the lower end of the lead conductor can be continuously used in the state cooled to the cooling medium temperature, or in the cooling process. Even if a stress load accompanying thermal contraction of the superconducting conductor occurs, the insulation coating of the lead conductor can be more unlikely to break. In addition, it is possible to further reduce the risk of the insulator of the lead conductor being destroyed due to the action of the stress generated by the thermal expansion of the lead conductor when energized, and the possibility of breaking the holding portion holding the lead conductor almost vertically. .

  One embodiment of the termination connecting portion of the superconducting power transmission cable of the present invention will be described in detail with reference to FIGS.

FIG. 1 is a longitudinal sectional view of an essential part showing an embodiment of a terminal connection part of a superconducting power transmission cable according to the present invention.
In FIG. 1, the difference from the above-described conventional example of FIG. 3 is that the connection between the lower end of the lead conductor 3 and the right end of the connecting conductor 2 that is linearly connected to the superconducting conductor 1 is connected by the flexible conductor 25. And the slidable connecting portion 30 at the boundary portion between the upper end portion of the portion 3a covered with the insulating coating 10 and the bare conductor portion 3b following the axial direction of the lead conductor 3. 2 points. The other basic configuration is similar to the conventional one.
Therefore, similar parts are denoted by the same reference numerals as those in FIG. 3, and the explanation thereof is partially omitted.

  As shown in FIG. 1, in one embodiment of the terminal connection portion of the superconducting power transmission cable of the present invention, the superconducting conductor 1 constituting the terminal portion of the superconducting power transmission cable laid in the horizontal direction in FIG. The flexible conductor 25 having a substantially L shape is connected to the lower end of the lead conductor 3.

Here, in the case of the terminal part of the superconducting power transmission cable, the terminal part of the superconducting conductor 1 of the superconducting power transmission cable and the terminal part of the connecting conductor 2 connected to the superconducting conductor 1 are shown (both in FIG. And the right terminal portion).
That is, when the end portion of the superconducting power transmission cable and the lower end portion of the lead conductor 3 are connected by the flexible conductor 25, the superconductor conductor 1 and the lead conductor 3 are directly connected by the flexible conductor 25. In some cases, the superconducting conductor 1 and the lead conductor 3 may be indirectly connected by the flexible conductor 25 via the connecting conductor 2 connected to the superconducting conductor 1.

  The lead conductor 3 passes through a temperature gradient portion 12 constituted by a liquid refrigerant layer 4 such as liquid nitrogen and a refrigerant gas layer 5 made of nitrogen gas or the like continuous with the liquid refrigerant layer 4. After passing through the high voltage lead-out portion 13 provided above the temperature gradient portion 12 and partitioned by the temperature gradient portion 12 and the flange 6, the tip portion is led to the outside.

The temperature gradient portion 12 is mainly composed of a liquid refrigerant layer 4 and a refrigerant gas layer 5 formed in an internal pressure vessel 22 made of SUS, and the internal pressure vessel 22 forms a vacuum heat insulating layer therein. It is covered with an external pressure vessel 21 made of SUS.
The high voltage lead-out portion 13 partitioned by the temperature gradient portion 12 and the flange 6 is mainly composed of an insulator 7, a fluid insulator 8 made of insulating oil, SF ₆ gas, or the like filled in the insulator 7 and a high voltage. It is constituted by an upper metal fitting 14 provided at the leading end of the drawing portion 13.
In FIG. 1, the flange 6 is separate from the lead conductor 3, but for example, the insulating coating 10 of the lead conductor 3 and the flange 6 may be formed of the same insulating resin and integrally formed. In this case, the lead conductor 3 is held almost vertically by the flange-shaped portion of the insulating coating 10 to perform axial positioning.

In the present invention, the lead conductor 3 is above the stress cone 11 provided at the upper end of the insulating coating 10 and is divided into two in the axial direction at the portion where the conductor is exposed. Yes. Then, both portions 3a and 3b are provided at the boundary between the divided lower portion, that is, the portion 3a having the insulating coating 10 and the portion 3b made of a bare conductor located above the portion 3a having the insulating coating 10. A slidable connecting portion 30 is provided so as to be relatively slidable in the axial direction.
Of course, the slidable connecting portion 30 does not impair the electrical continuity between the conductors of the portion 3a having the insulating coating 10 and the portion 3b made of a bare conductor.

FIG. 2 shows an enlarged longitudinal sectional view of the slidable connecting portion 30.
As shown in FIG. 2, a hole, that is, a receiving portion provided so that the central axis thereof coincides with the central axis of the lead conductor 3 is provided at the lower end of the portion 3 b made of a bare conductor. In this receiving portion, for example, a slidable connection member 31 such as a multi-contact is fitted. And in this slidable connection member 31, the front-end | tip part of the part 3a which has the said insulating coating 10 is slidably fitted to the axial direction of the drawer | drawing-out conductor 3.
Of course, the method of configuring the slidable connecting portion 30 is not limited to the method of using the slidable connecting member 31 such as multi-contact as in this embodiment.

  By the way, a gap having an axial length ε is provided between the bottom surface of the hole provided at the lower end of the portion 3b made of a bare conductor and the tip of the portion 3a having the insulating coating 10, as shown in FIG. The slidable length (margin) is adjusted by adjusting the length ε. The value of ε is appropriately determined according to the length and material of the lead conductor 3. That is, the elongation in the axial direction when the lead conductor 3 thermally expands may be determined by calculation.

As shown in FIG. 1, the conductor of the portion 3 a having the insulating coating 10 has an outer diameter of the portion located on the high voltage lead-out portion 13 side relatively to that of the portion located in the temperature gradient portion 12. It is enlarged. This is because the fluid insulator 8 in the insulator 7 is designed to be less likely to be deprived of heat toward the refrigerant gas layer 5 or the liquid refrigerant layer 4 through the lead conductor 3. That is, the fluid insulator 8 is prevented from being solidified or liquefied to lower the insulation strength.
However, the present invention is essentially irrelevant to the outer diameter of the lead conductor 3, and is not limited to that of the embodiment shown in FIG. 1. For example, the conductor outer diameter of the portion 3a having the insulating coating 10 is changed from the upper end to the lower end. There is no problem even if they have the same outer diameter.

  In the above embodiment, the slidable connecting member 31 is fitted into a receiving portion formed at the lower end of the portion 3b made of a bare conductor, and the tip of the portion 3a having the insulating coating 10 is slidably fitted therein. However, conversely, a hole for fitting the slidable connecting member 31 is provided at the tip of the portion 3a having the insulating coating 10, and the slidable connecting member 31 is fitted into the hole to be made of a bare conductor. The lower end of the portion 3b may be slidably fitted into the slidable connection member 31.

  As described above, the connection between the terminal portion of the superconducting power transmission cable and the lower end portion of the lead conductor 3 is connected by the flexible conductor 25, and the portion 3a having the insulating coating 10 and the portion 3a having the insulating coating 10 are located above. The slidable connection portion 30 is provided at the boundary with the portion 3b made of a bare conductor located in the base so that both the portions 3a and 3b can slide in the axial direction, whereby the end connection of the superconducting power transmission cable of the present invention is achieved. In this section, the stress generated mainly due to the thermal contraction of the superconducting conductor during the cooling process is absorbed and relaxed by the flexible conductor 25, and the stress generated by the thermal expansion of the lead conductor 3 during energization is mainly slid. The dynamic connection 30 absorbs this and relaxes it.

As a result, it is difficult to apply bending stress due to stress from the superconducting power transmission cable side to the lead conductor 3. Further, the load stress on the holding portion of the lead conductor 3 due to the expansion of the lead conductor 3 is further reduced and alleviated.
Therefore, even if the polymeric insulating coating 10 at the lower end of the lead conductor 3 is continuously used in a state of being cooled to the cooling medium temperature, a stress load due to thermal contraction of the superconducting conductor 1 occurs during the cooling process. However, the insulation coating 10 of the lead conductor 3 can be more unlikely to break.
At the same time, the action of the stress generated by the thermal expansion of the lead conductor during energization may cause damage to the insulator of the lead conductor and the risk of breaking the holding part that holds the lead conductor almost vertically. It is possible to provide a terminal connection portion of a superconducting power transmission cable that can be reduced and stable for a long period of time.

It is a principal part longitudinal cross-sectional view which shows an example of the termination | terminus connection part of the superconducting power transmission cable of this invention. FIG. 2 is an enlarged longitudinal sectional view showing an example of a slidable connection provided on the lead conductor in FIG. 1. It is a principal part longitudinal cross-sectional view which shows an example of the termination | terminus connection part of the conventional superconducting power transmission cable.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Superconductor 3 Lead conductor 3a Part 3b which has insulation coating Part 4 which consists of a bare conductor 4 Liquid refrigerant layer 5 Refrigerant gas layer 6 Flange 7 Insulator 8 Fluid insulator 10 Insulation coating 12 Temperature gradient part 13 High voltage extraction part 25 Flexible Conductive conductor 30 Sliding connection part 31 Sliding connection member

Claims (1)

  A superconducting power transmission cable terminal connection part for taking out the current flowing in the superconducting conductor provided in at least one end of the superconducting power transmission cable that performs power transmission in a superconducting state, into a normal temperature atmosphere. And a lead conductor that is drawn from cryogenic temperature to room temperature through a high voltage lead portion provided above, and the lead conductor is located at a portion located in the temperature inclined portion and at a lower portion of the high voltage lead portion. A portion of the bare conductor extending above the portion provided with the insulating coating is provided with a slidable connecting portion having slidability in the conductor axial direction, and the drawer The end of the superconducting power transmission cable is characterized in that a flexible conductor for electrically connecting the end of the superconducting power transmission cable substantially perpendicular to the lead conductor is connected to the lower end of the conductor. Connection portion.

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