KR102581659B1 - Terminal device for superconducting cable - Google Patents

Abstract

The present invention relates to a superconducting cable terminal device, which provides a connection between a current lead disposed at room temperature and a superconducting cable disposed in a cryogenic refrigerant tank, comprising the current lead and the superconducting cable and connecting them to each other. A connection portion formed by: a solid insulating bushing formed outside the connection portion; And, a refrigerant circulation path that is connected from the outside to the inside of the solid insulating bushing to form a high-voltage insulation path, and cools the connection portion by supplying refrigerant to cool it by heat exchange, thereby forming a heat balance portion on the connection portion. A superconducting cable terminal for improving insulation strength, wherein the refrigerant circulation path includes an internal connection path connected from the outside to the inside, and a bypass connection path connected to the internal connection path and formed along the inner circumferential surface of the solid insulating bushing. The device is a technical element. Accordingly, a refrigerant circulation path is formed in the insulating bushing that surrounds the connection connecting the current lead and the superconducting cable, and the connection is cooled by circulating the refrigerant, and a connection that serves as a heat balance point is included inside the insulating bushing to ensure insulation and cooling. This is done at the same time, but the refrigerant circulation path is formed in the form of a three-dimensional bypass passage, so the insulation strength is improved and the overall volume can be reduced, and the superconducting cable can be connected directly in a straight line like existing commercial products, making it easy in terms of form. It has the advantage of being able to replace existing facilities and create groundbreaking electricity for actual system use and commercialization.

Description

Terminal device for superconducting cable to improve dielectric strength

The present invention relates to a superconducting cable terminal device for improving dielectric strength, and more specifically, a refrigerant circulation path that forcibly cools the current lead and a connection part that serves as a thermal balance point are included inside the insulating bushing to achieve simultaneous insulation and cooling. At the same time, it relates to a superconducting cable terminal device for improving dielectric strength in which the dielectric strength is improved and the overall volume is reduced by forming the refrigerant circulation path in the form of a three-dimensional bypass passage.

In general, a superconducting cable terminal device refers to a device that connects a general overhead transmission line made of conductors or power equipment such as GIS, transformers, etc., and a superconducting cable. In other words, it is a connection device for connecting a superconducting cable that transmits power at extremely low temperatures to an overhead transmission line at room temperature or to power equipment such as circuit breakers and transformers. This terminal device is a comprehensive system that must solve the electrical, mechanical, and thermal problems that arise when connecting a current circuit at room temperature to a superconducting circuit at liquid nitrogen or liquid helium temperature.

There are various technologies for such terminal devices, and “Terminal Structure for Superconducting Cables” is introduced in Korea Intellectual Property Office Registered Patent Publication No. 10-508710. As shown in FIGS. 1 and 2, the prior art includes a room temperature section 330 filled with insulating oil 334, the room temperature section 330 and the fixing flange 230 combined, and a current lead section 350. In the terminal structure for a superconducting cable consisting of a cryogenic portion 220 in a vacuum state, the electric field concentrated on the current lead portion 350 is alleviated inside the joining portion of the room temperature portion 330 and the cryogenic portion 220, A boundary 400 is formed to maintain airtightness between the room temperature section 330 and the cryogenic section 220.

In addition, the boundary portion 400 includes a metal conductor rod 410 connecting the upper conductor 340 inserted in the room temperature section 330 and the lower conductor 240 inserted in the cryogenic section 220, and the room temperature section ( 330) and a buried electrode 420 that is flange-coupled with the cryogenic unit 220 and whose both ends are rounded while surrounding the metal conductor rod 410, and the metal conductor rod 410 and the buried electrode 420. It is formed of an insulating material 430 that is injection molded together.

However, the prior art does not specify the medium of the boundary portion, but considering that the ends of the upper and lower solid insulating bushings have a surface insulating structure, it is understood to be a structure filled with vacuum or gas. In this structure, the lower surface insulation of the upper solid insulating bushing is The structure and the upper surface insulation structure of the lower solid insulation bushing are essential to secure electrical insulation properties. This structure has the advantage of avoiding weakening of the insulation characteristics due to gas-liquid interface flow such as bubbles by placing the gas-liquid interface at the ground plane in terms of operation. However, these conventionally invented or manufactured superconducting terminals must have 2 or 4 surface insulation or interface insulation structures in order to pursue both electrical insulation properties and cooling functions internally, so the overall volume is large, and the superconducting cable in which the superconducting conductor is present is required. It is a structure in which the central conductor must be directly exposed to the refrigerant in various parts where high voltage is applied in order to keep the end part stable in a cryogenic state. For this reason, the final manufactured superconducting terminal has a problem in that it is difficult to apply directly to the steel tower or substation connection of the existing transmission line in terms of shape and size.

As another prior art, Korea Intellectual Property Office Patent Publication No. 10-0590200, “Terminal device for superconducting cable,” is introduced.

The prior art is shown in Figure 3 or Figure 4.

In Figure 3, it is composed of an upper room temperature section 10, a lower cryogenic section 20, and a current introduction line 30 penetrating the inside of the room temperature section 10 and the cryogenic section.

The room temperature part 10 is a part where the current lead line 30 connected to the external normal conduction cable is introduced, and insulating oil or insulating gas (11) is inside to insulate the high voltage current lead line 30 penetrating the inside from the outside. ) is filled, and an insulator 12 is formed on the outside.

The cryogenic section 20 is located at the lower part of the room temperature section 10 and consists of a vacuum container 21 in which a vacuum layer is maintained between the inner wall 23 and the outer wall 22, and liquid nitrogen is injected and circulated inside. A first liquid nitrogen layer 24 is formed, and a gaseous nitrogen layer 25 is formed on the top of the first liquid nitrogen layer 24, which is formed by vaporizing the liquid by heat flowing in through the current introduction line. At this time, a partition 26 is installed to separate the first liquid nitrogen layer 24 from the second liquid nitrogen layer 29 for cooling the superconducting cable 1. And a liquid nitrogen inlet 27 and a liquid nitrogen outlet 27' are formed.

The prior art has a problem in that additional heat loss occurs in the first liquid nitrogen layer 24 due to convection of the gaseous nitrogen layer 25 itself, thereby increasing the cooling load on the terminal device for the superconducting cable.

In another prior art, Figure 4, a convection blocking plate 40 to reduce convection of gaseous nitrogen is installed in the section where the gaseous nitrogen layer 25 is formed.

However, the terminal device for the conventional superconducting cable needs to safely maintain the gas-liquid interface, which has weak insulation properties, and separates the exposed conductor to which high pressure is applied between gas and liquid or gas regardless of the suppression of convection in the upper gas section. /To maintain insulation at the liquid interface, two insulating bushing structures are usually required. Additionally, since the gas/liquid interface varies depending on the amount of heat intrusion or the amount of heat generated by the conductor, a significant section where the liquid level can vary must be secured to continuously secure insulation performance.

In particular, in the case of Figure 4, in order to improve the stability of the gas-liquid interface, several partition walls are installed in a structure to minimize convection phenomenon in the gas portion to prevent gas convection, but as in Figures 3 and 4, in any case When a variable gas-liquid interface is used as an insulating structure, there is a problem in that the insulation characteristics along the interface are lowered, so the diameter of the enclosure becomes larger, and the stability according to the amount of heat intrusion is not satisfactory.

Another prior art is the U.S. Patent and Trademark Office Publication No. US2014/0243206 A1 (published on August 28, 2014), which involves forming a high-voltage bushing on the outer surface of a copper conductor and electrically connecting the copper conductor and a superconducting cable in a vacuum. A structure has been introduced that cools the terminals of the copper conductor, the terminals of the superconductor cable, and their connections by forming a connecting connection and heat exchanging the copper conductor using an external helium refrigerator. However, this involves forming separate insulation and cooling structures. Due to Sikkim, this also becomes bulky, so there is a problem that it is difficult to apply directly to the pylon or substation connection of the existing transmission line.

Korea Intellectual Property Office Registered Patent No. 10-0590200 Korea Intellectual Property Office Patent No. 10-0508710 U.S. Patent and Trademark Office Publication No. US2014/0243206 A1

The present invention was devised to solve the problems of the prior technologies described above. A refrigerant circulation path is formed in an insulating bushing surrounding a connection connecting a current lead and a superconducting cable, and the connection is cooled by circulating the refrigerant to serve as a thermal balance point. A superconducting cable terminal device for improving dielectric strength that insulates and cools simultaneously by including a connection part inside the insulating bushing, but improves dielectric strength and reduces overall volume by forming the refrigerant circulation path in the form of a three-dimensional bypass passage. The purpose is to provide.

Accordingly, the present invention for achieving the above object is a superconducting cable terminal device for connection between a current lead disposed at room temperature and a superconducting cable disposed in a cryogenic refrigerant tank, comprising the current lead and the superconducting cable, and A connection portion formed by being connected to; a solid insulating bushing formed outside the connection portion; And, a refrigerant circulation path that is connected from the outside to the inside of the solid insulating bushing to form a high-voltage insulation path, and cools the connection portion by supplying refrigerant to cool it by heat exchange, thereby forming a heat balance portion on the connection portion. A superconducting cable terminal for improving insulation strength, wherein the refrigerant circulation path includes an internal connection path connected from the outside to the inside, and a bypass connection path connected to the internal connection path and formed along the inner circumferential surface of the solid insulating bushing. The device is a technical element.

Here, a reinforcing insulator is formed on the lower part of the solid insulating bushing to surround a portion connecting the superconducting cable and the current lead; A push bar formed at a lower portion of the reinforcing insulator to surround the reinforcing insulator; In addition, one side is coupled to the lower part of the refrigerant tank, and the other side is in contact with the lower part of the pusher, and is preferably configured to further include an elastic body that supports the pusher by elastic force.

The solid insulating bushing is. It is preferable that a reinforcing insulator is formed at the bottom of the solid insulating bushing to surround the portion connecting the superconducting cable and the current lead.

The refrigerant circulation path includes a refrigerant inflow path formed in the solid insulating bushing and through which refrigerant flows into the solid insulating bushing; a refrigerant discharge circuit formed in the solid insulating bushing in correspondence with the refrigerant inlet circuit and connected to the refrigerant tank or outlet to discharge the introduced refrigerant to the refrigerant tank or the outside; A current lead cooling circuit connects the refrigerant inlet circuit and the refrigerant discharge circuit between the refrigerant inlet circuit and the refrigerant discharge circuit, and is formed outside or penetrating the current lead to cool the connection. It is desirable.

Preferably, the current lead cooling circulation path is formed in a spirally bent coil shape along the axis of the current lead.

The current lead includes a room temperature current lead connected to an external external connection terminal; an upper current lead coupled to the room temperature current lead and extending downward; It is preferable to include a lower current lead, one end of which is connected to the upper current lead, and the other end of which are connected to the superconducting cable.

The lower current lead is preferably formed with a first flange protruding toward the upper current lead, and the upper current lead is fitted with the first flange.

It is preferable to include a current lead cooling circulation path that is formed to penetrate the contact surface of the upper current lead in contact with the first flange and through which a refrigerant that cools the current lead is circulated.

The current lead cooling circuit preferably has a semicircular cross section.

In the current lead, a fixing part is formed to protrude or recess on the current lead to support the load generated as the superconducting cable conductor is connected and to minimize mechanical stress generated within the solid insulating bushing due to cryogenic cooling. desirable.

The current lead and the superconducting cable are preferably arranged parallel to each other along the longitudinal direction.

The solid insulating bushing and reinforcing insulator are preferably made of epoxy, PPLP (polypropylene laminated paper), and a mixture thereof.

The refrigerant is preferably liquid nitrogen or liquid helium.

It is preferable that a push band is formed at the lower part of the reinforcing insulator to surround the reinforcing insulator.

Preferably, one side of the refrigerant tank is coupled to the lower part of the refrigerant tank, and the other side is in contact with the lower part of the pusher, and a spring is formed to support the pusher by elastic force.

It is preferable that a superconducting cable is installed in the refrigerant tank by being introduced into the lower side of the refrigerant tank.

Accordingly, a refrigerant circulation path is formed in the insulating bushing that surrounds the connection connecting the current lead and the superconducting cable, and the connection is cooled by circulating the refrigerant, and a connection that serves as a heat balance point is included inside the insulating bushing to ensure insulation and cooling. This is done at the same time, but the refrigerant circulation path is formed in the form of a three-dimensional bypass passage, so the insulation strength is improved and the overall volume can be reduced, and the superconducting cable can be connected directly in a straight line like existing commercial products, making it easy in terms of form. It has the advantage of being able to replace existing facilities and create groundbreaking electricity for actual system use and commercialization.

According to the configuration of the present invention described above, a refrigerant circulation path that forcibly cools the current lead and a connection part that serves as a fixed thermal balance point are included in the insulating bushing, so that the refrigerant circulation path is formed in the form of a three-dimensional bypass passage, thereby increasing the dielectric strength. The overall volume of the superconducting cable terminal device can be dramatically reduced by improving the superconducting cable connection and reinforcing it with a solid insulation structure.

In addition, because superconducting cables can be directly connected to terminals in a straight line like existing commercial products, they can easily replace existing facilities in terms of form, creating groundbreaking electricity for real-world use and commercialization.

In addition, by eliminating the gas space in the refrigerant tank, the insulation characteristics are improved even if the volume is reduced, which has the effect of enabling stable operation.

1 is a cross-sectional view of a conventional terminal structure for a superconducting cable;
Figure 2 is an enlarged view of the main part of Figure 1;
Figure 3 is a cross-sectional view of a cable terminal device according to another prior art;
Figure 4 is a diagram showing the shape of the convection blocking plate installed in the gaseous nitrogen layer of Figure 3;
Figure 5 is a cross-sectional view of a superconducting cable terminal device for improving dielectric strength according to the present invention;
Figure 6 is an enlarged view of the main part of Figure 5;
Figure 7 is a main longitudinal cross-sectional view showing the refrigerant circulation path.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

As seen in the prior art above, the problems of the existing system are summarized to ensure a thermal gradient with the room temperature section in order to secure cooling characteristics so that the superconducting cable can operate stably, and to simultaneously secure electrical insulation characteristics. . Here, the role of the thermal gradient is to stabilize the superconducting cable conductor at a temperature where the superconductivity phenomenon is maintained by forcibly cooling the heat invading from the external room temperature and the heat generated due to current flow. To put it simply, this means that external intrusion heat and heat generated from the copper current lead must be continuously removed. In order to secure this function, the superconducting cable conductor is exposed to liquid nitrogen, and the lower part of the copper current lead connected at the top is also exposed and connected to liquid nitrogen, so that external intrusion heat and heat generated by the copper conductor are cooled by liquid nitrogen. Since high voltage is applied to the conductor, an essential insulation structure is added.

The problem with this existing system occurs because the structure in which a certain section of the copper conductor connected to room temperature is exposed to liquid nitrogen becomes longer due to the insulating interface. Therefore, if the conductor heat exchange part for cooling can be included in a solid insulating bushing that secures the insulating interface, the possibility of reducing 2 to 4 weak insulating interfaces to one was evaluated.

At first, we did not design a thermal cooling point, but considered a structure that surrounds the entire structure with solid insulation. In this case, a significant section of the superconducting cable connection had the problem of not maintaining the superconductivity phenomenon, so it was evaluated as not applicable.

Next, we examined the structure of designing a forced cooling section in front of the superconducting cable to maintain the superconducting phenomenon throughout the superconducting cable. In order to forcibly discharge heat from a certain part of the copper conductor, it had to be structured to allow liquid nitrogen, which is used as a cooling medium, to flow, and the part through which liquid nitrogen flows creates a liquid-solid interface, forming an existing conductor that exhibits weak insulating properties. The problem appeared as is.

In order to solve this problem, the electrical insulation properties of the liquid-solid interface are evaluated, and a structure is formed to secure a liquid nitrogen path with improved dielectric strength by forming a curved, three-dimensional bypass passage within a bushing made of epoxy. was designed. The liquid-solid interface does not necessarily have to be connected in a straight line, and even if it is folded or bent, there is no additional reduction in insulating properties. However, the plane parallel to the electric field direction from the conductor to the ground plane needs to be avoided as much as possible because the applied electric field per unit length is greater than the insulation characteristic. Even if a partial discharge phenomenon that occurs due to a small portion being parallel to the electric field does not lead to a full discharge, if a discharge phenomenon occurs within or on the surface of a solid insulator in the long term, there is a risk of shortening the lifespan by causing continuous damage to the insulator. It could be a problem. To avoid this problem, even in existing terminal structures, an insulating surface is designed that is as non-parallel to the electric field direction as possible. However, if the non-parallel insulating sides are folded, the insulating properties of each side can be stable. With this in mind, an insulating passage through which liquid nitrogen can flow within the epoxy bushing was designed. In this structure, the possibility of replacing the existing room temperature terminal structure is secured because the superconducting cable can be directly connected in a straight line to the room temperature aerial bushing visible from the outside.

The structure of the embodiment of the present invention for achieving the above object is generally, in a superconducting cable terminal device for connection between a current lead disposed at room temperature and a superconducting cable disposed at extremely low temperature, (1) the current lead and the superconducting cable a solid insulating bushing that includes a connection part for connecting cables therein and is formed to connect the current lead and the superconducting cable; (2) A fixed part structure in which the superconducting cable is directly connected and the current lead to which mechanical load is applied has a protruding or depressed part and an adhesive treatment in a certain part in the middle to ensure airtightness and mechanical load resistance characteristics according to temperature changes. and, (3) a refrigerant circulation path passing through the solid insulating bushing and the current lead and circulating a refrigerant for cooling the current lead; (4) A heat balance unit located on the current lead in the insulating bushing that effectively cools the amount of heat generated from the current lead or the refrigerant passing through the refrigerant circulation path entering from the outside; (5) a refrigerant tank in which the superconducting cable is placed so that the refrigerant that has passed through the refrigerant circulation path and the heat balance unit flows in to maintain the cooled state of the superconducting cable; (6) a reinforcing insulator that can dramatically reduce the size of the connection by not directly exposing the terminal conductor portion of the superconducting cable to the refrigerant; (7) a superconducting cable characterized by including a push bar to prevent movement or deformation of the reinforcing insulator This is achieved by cable terminal equipment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the embodiments of the present invention.

As shown in FIGS. 5, 6, and 7, the superconducting cable terminal device 100 includes a current lead 200 that is placed at room temperature and connected to external devices, and a superconducting cable that is placed at a cryogenic temperature and acts as a superconductor. (300) is for connection of the connection part (J), which is connected to each other, and the connection part includes a current lead 200 and a superconducting cable 300. This terminal device includes a current lead 200 and a superconducting cable 300. It includes a cable 300, a solid insulating bushing 400, a refrigerant circulation path 500, a refrigerant tank 600, a reinforced insulator 410, a push rod 700, and a spring 800.

Here, the current lead 200 can be made of any material that can conduct electricity, but it is preferable that it is copper (Cu), copper alloy (Cu alloy), aluminum (Al), or aluminum alloy (Al alloy). The superconducting cable 300 is preferably a high-temperature superconducting cable capable of exhibiting superconductivity under a liquid nitrogen atmosphere, but is not limited thereto.

The current lead 200 of the present invention is installed in the room temperature section (R) where room temperature insulating gas 211 is charged and a room temperature bushing 212 is formed on the outside, and the current lead 200 is connected to the external connection terminal 201. do.

The current lead 200 and the superconducting cable 300 of the present invention are arranged parallel to each other along a straight line or longitudinal direction. Alternatively, even if the current lead 200 and the superconducting cable 300 are not parallel, the angle at which the current lead 200 and the superconducting cable 300 are coupled can be freely adjusted.

In the case of a conventional superconducting cable terminal device, Joule's heat is generated as current flows into the current lead from the outside. The point where the current lead and the superconducting cable are connected is maintained at a stable temperature to maintain the superconducting cable in a stable cryogenic state. It must be maintained at thermal equilibrium. Therefore, in order to achieve thermal balance, the Joule heat generated by or intruding through the current lead must be cooled. In order to cool the Joule heat, it is necessary to have a structure in which a part of the current lead is cooled by a refrigerant. Also, in the case of superconducting cables, they must be impregnated with refrigerant because they must exist in a cooled state at low temperatures. Therefore, in order to allow part of the current lead and the superconducting cable to be impregnated with the refrigerant, the overall volume of the refrigerant tank is formed to be large. In particular, in the case of conventional superconducting cable terminal devices, the current leads are joined together at an angle of approximately 90° to reduce heat transfer so that the Joule heat of the current leads does not affect the superconducting cable. Since they are connected at 90°, it is difficult to install additional insulators, and the overall The terminal structure has an 'L' shape, which is different from the existing 'I' shaped transmission line terminal device, and the installation area is expanded.

Therefore, as in the present invention, the current lead 200 and the superconducting cable 300 are arranged in a straight line, or the superconducting cable terminal device ( 100), the overall volume and installation area can be reduced by moving the position of the thermal balance point and installing additional reinforcing insulators during the field connection process. If the angle between the current lead 200 and the superconducting cable 300 exceeds 20°, the external shape becomes 'L' shaped, thereby increasing the installation area and reducing the effect of the present invention. However, the installation space of the superconducting cable terminal has an 'L' shape, so even if it is combined at a close to right angle, the volume increases to some extent. However, if the thermal balance point is moved and a solid insulator is added to the right angle part, it is larger than the existing superconducting terminal. The volume can be reduced.

The solid insulating bushing 400 includes a connection portion (J) inside which connects the current lead 200 and the superconducting cable 300, and includes a reinforcing insulator 410 so that the current lead 200 and the superconducting cable 300 are insulated. ) and is formed to surround the current lead 200 and the superconducting cable 300. In the present invention, the solid insulating bushing 400 is formed to surround the current lead 200, and the solid insulating bushing 400 is formed on the lower side of the solid insulating bushing 400 and the portion connecting the superconducting cable 300 and the current lead 200. Separately from the bushing 400, a reinforcing insulator 410 is formed to surround the connection portion. Here, the reinforced insulator 410 serves to surround the end of the superconducting cable 300, which may be exposed to liquid nitrogen in the refrigerant tank 600, so that the end of the superconducting cable 300 is not directly exposed to liquid nitrogen. .

The solid insulating bushing 400 is formed to insulate the current lead 200, and exists not only to insulate but also to protect the current lead 200 from external shock. This solid insulating bushing 400 is formed in a pillar shape surrounding the current lead 200, and is formed so that its diameter gradually decreases as it gets closer to both ends of the current lead 200. The solid insulating bushing 400 may be selected from the group consisting of epoxy, PPLP (polypropylene laminated paper), and mixtures thereof. The portion where the refrigerant circulation path 500 is formed is made of epoxy, a pre-manufactured solid material. It is more desirable.

The reinforcing insulator 410 is formed to insulate the portion where the superconducting cable 300 and the current lead 200 are connected, and is formed to surround the current lead 200 as well as the terminal of the superconducting cable 300. A portion of the solid insulating bushing 400 is exposed to the outside, while the reinforcing insulator 410 is disposed in a refrigerant tank 600 containing refrigerant. The reinforcing insulator 410 is arranged to surround the end of the solid insulating bushing 400 surrounding the current lead 200 to the superconducting cable 300 immersed in refrigerant. Like the solid insulating bushing 400, the reinforcing insulator 410 is formed so that its diameter gradually decreases toward the end. As a result, only the end of the superconducting cable 300 is surrounded by the reinforcing insulator 410, and the area other than the end of the superconducting cable 300 is exposed to the refrigerant in the refrigerant tank 600 without the reinforcing insulator 410. comes into contact. As described above, the reinforcing insulator 410 not only serves the purpose of insulation, but also serves to prevent the end of the superconducting cable 300 from being directly exposed to liquid nitrogen.

Here, the reinforcing insulator 410 may be selected from the group consisting of epoxy, PPLP (polypropylene laminated paper), and mixtures thereof. Among them, it is preferable to form using PPLP, and the PPLP is sequentially stacked one by one. Formed to have a certain volume.

The present invention includes a refrigerant circulation path 500 for cooling the current lead 200 in order to reduce the volume of the refrigerant tank 600 in the bulky superconducting cable terminal device 100 by the refrigerant tank 600.

The refrigerant circulation path 500 refers to a passage through which refrigerant circulates through the solid insulating bushing 400 and the current lead 200 to cool the current lead 200. Here, the solid insulating bushing 400 surrounds the current lead 200, and it is desirable for the refrigerant circulation path 500 to be formed in the solid insulating bushing 400.

Through this refrigerant circulation path 500, the current lead 200 can be forcibly cooled not only in the refrigerant tank 600 but also areas of the current lead 200 that are not immersed in the refrigerant tank 600.

The refrigerant circuit 500 consists of a refrigerant inlet circuit 510, a refrigerant discharge circuit 520, and a current lead cooling circuit 530. The refrigerant inflow circuit 510 is formed in the solid insulating bushing 400 and is a passage through which refrigerant flows into the solid insulating bushing 400.

This refrigerant inflow circuit 510 is formed with an inlet 511 through which refrigerant flows in from the outside, and the refrigerant inlet circuit 510 connects a current lead 200 disposed at the center from the outer surface of the solid insulating bushing 400. It is pierced so that the refrigerant flows in, but not in a straight line but in a three-dimensional bypass shape.

At this time, the three-dimensional bypass passage is formed by forming an internal connection passage 501 connected from the outside to the inside, and a bypass passage connected to the internal connection passage 501 and formed along the inner circumferential surface of the solid insulating bushing 400 ( 502) is achieved by forming. Here, as shown in FIG. 7, the dielectric strength of the terminal device can be improved by forming a plurality of the internal connection path 501 and the bypass connection path 502 and connecting them to lengthen the length of the refrigerant inlet circulation path 510. It is a structure.

The refrigerant flowing in from the outside passes through the internal connection path 501 and the bypass connection path 502 of the refrigerant inflow circulation path 510 and flows into the current lead cooling circulation path 530.

The current lead cooling circuit 530 serves to connect the refrigerant inlet circuit 510 and the refrigerant discharge circuit 520 between the refrigerant inlet circuit 510 and the refrigerant discharge circuit 520. This current lead cooling circulation path 530 is formed to penetrate the current lead 200 in order to cool the current lead 200 and has a circular or semicircular cross-sectional shape. At this time, the current lead cooling circulation path 530 is preferably in the shape of a coil bent spirally along the axis of the current lead 200. When the current lead cooling circulation path 530 passes through the coil-shaped current lead 200, the contact area of the current lead 200 with the refrigerant increases, and thus the current lead 200 can be effectively cooled.

In particular, since it is formed in a spiral shape along the axis of the current lead 200, cooling is efficient because cooling is performed on the entire surface along the diameter of the current lead 200, rather than cooling only one side. In terms of cooling efficiency, it is preferable that the current lead cooling circulation path 530 penetrating the current lead 200 is formed through an area between the center and the outermost edge of the current lead 200, rather than being formed at the outermost edge from the center of the current lead 200. When the current lead cooling circulation path 530 is formed in the outermost area of the current lead 200, cooling is performed smoothly in the outermost area, but cooling may not be performed smoothly as the central area becomes farther away from the refrigerant.

The refrigerant that cools the current lead 200 through the current lead cooling circuit 530 passes through the refrigerant discharge circuit 520 and is discharged to the outside through the outlet 521 formed at the end of the refrigerant discharge circuit 520. It flows into the refrigerant tank 600 along the tank inflow path 610. If there is a lot of heat infiltrating the current lead 210 and the heat generated is a burden to maintain the stable state of the superconducting cable 300, the refrigerant inlet 511 and the refrigerant inlet circuit 510 are installed for stable operation of the superconducting cable 300. ), a separate terminal cooling path consisting of a current lead cooling circuit 530, a refrigerant discharge circuit 520, and a refrigerant outlet 521 can be installed.

Here, the refrigerant discharge circuit 520 is formed in the solid insulating bushing 400 in correspondence with the refrigerant inlet circuit 510, and the refrigerant discharge circuit 520, like the refrigerant inlet circuit 510, is an internal connection path 501. and a bypass connection path 502 that is connected to the internal connection path 501 and is formed along the inner circumferential surface of the solid insulating bushing 400, thereby lengthening the length of the refrigerant discharge circulation path 520, thereby increasing the length of the terminal device. It is a structure that can improve dielectric strength.

In this way, the refrigerant that cools the current lead 200 through the refrigerant circulation path 500 passes through the refrigerant circulation path 500 and passes through the refrigerant tank inflow path 610 formed between the refrigerant tank 600 and the reinforced insulator 410. flows into the refrigerant tank (600).

Inside the refrigerant tank 600, the end of the solid insulating bushing 400, a superconducting cable 300, a reinforcing insulator 410, a pusher 700, and a spring 800 are disposed, which are connected to the refrigerant tank 600. Cooled through incoming refrigerant. The refrigerant flowing through the refrigerant circulation path 500 is not vaporized due to the structure of the refrigerant circulation path 500, but flows into the refrigerant tank 600 in a liquid state, and through this, the internal superconducting cable 300 can be cooled without difficulty. .

The refrigerant tank 600 of the present invention is formed to have the same or similar diameter as the solid insulating bushing 400 so as to minimize the volume of the superconducting cable terminal device 100. The conventional refrigerant tank included a large volume refrigerant tank to cool the current lead heated by Joule heat, but in the case of the present invention, the refrigerant circulation path 500 that forcibly cools the current lead 200 is formed separately. The temperature of the current lead 200 flowing into the refrigerant tank 600 is not high, and therefore the volume of the refrigerant tank 600 does not need to be large. The current lead 200 generates Joule heat throughout the entire section due to the current. When the refrigerant circulation path 500 is installed in the middle area of the current lead 200, the temperature of the cooled current lead 200 increases with the current lead 200. ) affects the entire area. That is, even if the current lead 200 is cooled in the central area, the ends that are close to the superconducting cable 300 are also cooled, thereby enabling thermal equilibrium with the superconducting cable 300. This refrigerant tank 600 is preferably made of a metal such as stainless steel, which has excellent strength.

At the bottom of the reinforcing insulator 410 is the connection portion (J), a solid insulating bushing 400 surrounding the connection portion (J), and an end of the current lead 200 and a superconducting conductor to support the reinforcing insulator 410. A push bar 700 is formed in contact with the lower part of the reinforcing insulator 410 that surrounds the connection portion of the cable 300. The pusher 700 is made of FRP material, etc., and serves to support the reinforcing insulator 410 so that the reinforcing insulator 410 and the solid insulating bushing 400 are in close contact with each other.

At the lower part of the push bar 700, a plurality of springs 800, which are elastic bodies that support the push bar 700 from the lower side, are formed along the lower surface of the refrigerant tank. The spring 800 is installed inside the refrigerant tank 600 so that the lower support becomes the lower surface of the refrigerant tank 600 and the upper support becomes the lower surface of the pusher 700. elastically supports.

The spring maintains the superconducting cable 300, current lead 200, solid insulating bushing 400, and reinforcing insulator 410 in a constant position and prevents them from being pulled down by gravity.

Typically, the current lead 200 and the superconducting cable 300 are assembled at room temperature and then cooled with a refrigerant. The current lead 200 and the superconducting cable 300 assembled at room temperature are cooled to a difference of at least 200°C. When this happens, the volume of all structures decreases. In this case, since it is made only of metal that can be designed to resist deformation, the mechanical bonding force of the current lead (200), superconducting cable (300), and refrigerant tank, etc., which are strongly mechanically coupled, can be maintained, but reinforcement that is additionally manufactured at the installation site is required. It is expected that the mechanical contact force with the insulator 410 may decrease and the configuration of the reinforcing insulator 410 itself may become loose. For this purpose, the push bar 700 and spring 800 are installed.

The room temperature current lead 202 is formed in the room temperature portion (R) of the superconducting cable terminal device 100 and is connected to the external connection terminal 201.

The upper current lead 210 refers to a current lead extending outside the solid insulating bushing 400, and the upper current lead 210 is connected to the room temperature current lead 202, and the lower current lead 220 is connected to the upper current lead 210. ), one end of which is coupled to the upper current lead 210 along the same axis, and the other end of which is coupled with the end of the superconducting cable.

The lower current lead 220 includes a first flange 221 protruding toward the upper current lead 210, and the upper current lead 210 protrudes toward the lower current lead 220 and the protrusion is the first flange ( 221) and are connected to each other. Through this first flange 221, the upper current lead 210 and the lower current lead 220 are not coupled and separated from each other, and additional components may be included to further strengthen the coupling.

Also, a protrusion that protrudes outward is formed on the outer surface of the upper current lead 210 among the current leads 200, and the protrusion forms the fixing portion 213. The solid insulating bushing 400 formed on the outer surface of the current lead 200 by forming the fixing part 213 serves to support and be stably coupled to the outer surface of the current lead 200.

Additional components for more firmly combining the upper current lead 210 and the lower current lead 220 can be combined using bolts, through which the upper current lead 210 and the lower main current lead 220 are connected. ) allows bolt connection, and no problem occurs even if the volume of the superconducting cable 300 is reduced.

In addition, a thermal balance section ( 214) is formed.

At this time, the current lead cooling circuit 530 can cool the current lead 200 through contact with the first flange 221. The current lead cooling circuit 530 can be configured in a circular or semi-circular shape, but it is preferable to have a simple semi-circular cross-section rather than a circular cross-section, which increases the manufacturing cost due to the complicated configuration.

In this way, when the current lead 200 is divided into the upper current lead 210 and the lower current lead 220, and the fixing part 213 is formed on the upper current lead 2101 and these are combined together, the superconducting cable 300 Even if a reduction in ) occurs, the current lead 200 is prevented from leaving its position, and separation between the current lead 200 and the superconducting cable 300 can also be prevented.

The refrigerant used in the present invention is a liquid refrigerant, preferably liquid helium or liquid nitrogen, which are commonly used. When supplying such refrigerant to the refrigerant circulation path 500, if you know the current value flowing into the current lead 200 and the type of material of the current lead 200, you can know the corresponding Joule heat value. In addition, the temperature according to the type of refrigerant Alternatively, the most appropriate environment for the superconducting cable terminal device 100 can be created by controlling the supply speed of the supplied refrigerant.

In the present invention, the thermal balance unit 214, which connects the current lead 200 and the superconducting cable 300 and serves as a thermal balance point, is not separately exposed within the refrigerant tank 600 as in the prior art, but is instead used as a solid insulating bushing. Because it is included in 400, the overall height of the superconducting cable terminal device 100 can be reduced. In addition, the volume of the refrigerant tank 600 can be reduced by the refrigerant circulation path 500 that forcibly cools the current lead 200 in areas other than the refrigerant tank 600, and the overall system operating conditions can be stably secured. there is. In addition, by forming part of the refrigerant circulation path 500 within the solid insulating bushing 400, insulation and cooling are achieved simultaneously, thereby reducing the overall volume.

Meanwhile, the refrigerant that has passed through the refrigerant circulation path 500 flows into the refrigerant tank 600. Due to the shape of the refrigerant circulation path 500 and the continuous supply of refrigerant, the refrigerant is not vaporized and can remain in a liquefied state, creating a liquid-gas interface. It has the advantage of not existing separately.

100: Superconducting cable terminal device 200: Current lead
201: external connection terminal 202: room temperature current lead
210: upper current lead 211: room temperature insulating gas
212: Room temperature bushing 213: Fixing part
214: thermal balance unit 220: lower current lead
221: first flange 300: superconducting cable
400: Solid insulating bushing 410: Reinforced insulator
500: Refrigerant circulation path 501: Internal connection path
502: Bypass connection path 510: Refrigerant inflow circulation path
511: Inlet 520: Refrigerant discharge circulation path
521: outlet 530: current lead cooling circuit
600: Refrigerant tank 610: Refrigerant tank inlet
700: pusher 800: spring
R: room temperature section J: connection section

Claims (17)

In the superconducting cable terminal device for connection between a current lead placed at room temperature and a superconducting cable placed in a cryogenic refrigerant tank,
a connection portion including the current lead and the superconducting cable and formed by being connected to each other;
a solid insulating bushing formed outside the connection portion; and,
A refrigerant circulation path is connected from the outside to the inside of the solid insulation bushing to form a high-voltage insulation path, and cools the connection portion by supplying refrigerant to cool it by heat exchange, thereby forming a heat balance portion on the connection portion. But,
The refrigerant circulation path includes an internal connection path connected from the outside to the inside, and a bypass connection path connected to the internal connection path and formed along the inner circumferential surface of the solid insulating bushing,
a reinforcing insulator formed at a lower portion of the solid insulating bushing to surround a portion connecting the superconducting cable and a current lead;
A push bar formed at a lower portion of the reinforcing insulator to surround the reinforcing insulator; and
One side is coupled to the lower part of the refrigerant tank, and the other side is in contact with the lower part of the pusher, and an elastic body supports the pusher by elastic force. A superconducting cable terminal device for improving dielectric strength, characterized in that it further includes. delete delete According to clause 1,
In the refrigerant circulation path,
a refrigerant inflow circuit formed in the solid insulating bushing and through which refrigerant flows into the solid insulating bushing;
a refrigerant discharge circuit formed in the solid insulating bushing in correspondence with the refrigerant inlet circuit and connected to the refrigerant tank or outlet to discharge the introduced refrigerant to the refrigerant tank or the outside;
A current lead cooling circuit connects the refrigerant inlet circuit and the refrigerant discharge circuit between the refrigerant inlet circuit and the refrigerant discharge circuit, and is formed outside or penetrating the current lead to cool the connection. A superconducting cable terminal device for improving dielectric strength, characterized in that. According to clause 4,
A superconducting cable terminal device for improving dielectric strength, characterized in that the current lead cooling circulation path is penetrated in a spirally bent coil shape along the axis of the current lead. According to clause 1,
The current lead is,
A room temperature current lead connected to an external external connection terminal;
an upper current lead coupled to the room temperature current lead and extending downward;
A superconducting cable terminal device for improving dielectric strength, comprising a lower current lead, one end of which is connected to the upper current lead, and the other end of which is connected to the superconducting cable. According to clause 6,
The lower current lead is formed with a first flange protruding toward the upper current lead, and the upper current lead is fitted with the first flange. A superconducting cable terminal device for improving insulation strength. According to clause 7,
A superconducting cable terminal device for improving dielectric strength, comprising a current lead cooling circuit formed to penetrate a contact surface of the upper current lead in contact with the first flange, and through which a refrigerant that cools the current lead is circulated. According to clause 8,
A superconducting cable terminal device for improving dielectric strength, wherein the current lead cooling circuit has a semicircular cross-section. In the superconducting cable terminal device for connection between a current lead placed at room temperature and a superconducting cable placed in a cryogenic refrigerant tank,
a connection portion including the current lead and the superconducting cable and formed by being connected to each other;
a solid insulating bushing formed outside the connection portion; and,
A refrigerant circulation path is connected from the outside to the inside of the solid insulation bushing to form a high-voltage insulation path, and cools the connection portion by supplying refrigerant to cool it by heat exchange, thereby forming a heat balance portion on the connection portion. But,
The refrigerant circulation path includes an internal connection path connected from the outside to the inside, and a bypass connection path connected to the internal connection path and formed along the inner circumferential surface of the solid insulating bushing,
In the current lead, a fixing part is formed to protrude or recess on the current lead to support the load generated as the superconducting cable conductor is connected and to minimize mechanical stress generated within the solid insulating bushing due to cryogenic cooling. A superconducting cable terminal device for improving dielectric strength. According to clause 1,
A superconducting cable terminal device for improving dielectric strength, wherein the current lead and the superconducting cable are arranged parallel to each other along a straight line or a longitudinal direction. According to claim 10,
The solid insulating bushing is.
A superconducting cable terminal device for improving insulation strength, characterized in that a reinforcing insulator is formed at the bottom of the solid insulating bushing to surround the part connecting the superconducting cable and the current lead.
According to claim 12,
A superconducting cable terminal device for improving dielectric strength, characterized in that the solid insulating bushing and reinforcing insulator are made of epoxy, PPLP (polypropylene laminated paper), and a mixture thereof.
The superconducting cable terminal device for improving dielectric strength according to claim 12, wherein a push bar is formed on a lower part of the reinforcing insulator to surround the reinforcing insulator.
According to clause 14,
A superconducting cable terminal device for improving dielectric strength, characterized in that one side of the refrigerant tank is coupled to the lower part of the refrigerant tank, and the other side is in contact with the lower part of the pusher to form an elastic body that supports the pusher by elastic force. The superconducting cable terminal device for improving dielectric strength according to claim 15, wherein the elastic body is a spring. The superconducting cable terminal device for improving dielectric strength according to claim 10, wherein a superconducting cable is installed in the refrigerant tank by being inserted into the lower side of the refrigerant tank.

Images