KR102213909B1 - Superconducting apparatus - Google Patents

Abstract

The present invention relates to a superconducting power device, wherein a superconducting element 13 accommodated in a cooling tank 10 filled with a refrigerant 11, and the superconducting element 13 are installed inside the cooling tank 10. An insulating structure 15 separated from the cooling tank 10 to insulate it, and a double curvature metal shielding ring 17 installed on a surface of the insulating structure 15 with a triple point for mitigating an electric field.
The present invention has the advantage of distributing an electric field concentrated in the triple point by installing a double-curvature metal shielding ring at the end of an insulating structure where the triple point occurs, thereby expecting an electric field relaxation effect.

Description

Superconducting power equipment{SUPERCONDUCTING APPARATUS}

The present invention relates to a superconducting power device, and more particularly, to a superconducting power device having a shield ring installed to mitigate an electric field at a point where an electric field is concentrated.

Superconducting power devices include superconducting cables, superconducting transformers, superconducting fault current limiters, superconducting motors, superconducting generators, and superconducting energy storage devices.

As shown in Fig. 1, the superconducting power device is a superconducting element 13 in a cooling tank 10 filled with a refrigerant 11 such as liquid nitrogen for cooling the superconducting element 13 and insulating a portion to which a high voltage is applied. ) Is received and cooled, and insulation is maintained by maintaining a gap between the superconducting element 13 and the cooling tank 10 with an insulating structure 15.

By the way, as shown in FIGS. 2A and 2B, a triple point, which is a part where the insulating structure 15 supporting the superconducting element 13, the refrigerant 11, and the support 10a (or the cooling tank 10) contacts ( At triple point (S), a weak point in which the electric field is concentrated is formed.

The triple point (S) is a vulnerability that shows abnormalities in the electric field, and it always exists in the internal structure of a superconducting power device.

The triple point is a junction of three different materials, and since the internal electric field distribution to the external electric field differs for each material, discontinuity occurs at the contact point and a sudden change in electric field distribution is induced.

Since insulation breakdown occurs frequently at the actual triple point, it is common to not trust the calculated value at the triple point (S) in the electric field analysis simulation.

One of the conventional solutions is to increase the distance between the boundary consisting of triple points corresponding to the high voltage part and the low voltage part of the insulating structure. However, when high voltage is applied, the insulation distance continues to increase for safety.

2B is an example of calculation. In the case of a transmission class superconducting fault current limiter, the electric field calculation result at the triple point is ~6.3kV/mm when calculating for 750kV because the high voltage part and the low voltage part are close to 600mm or less. This is because dielectric breakdown is expected in general liquid nitrogen, so electric field relaxation at triple points is required for a compact design.

Publication Patent Publication No. 2013-0038584 (name: vacuum circuit breaker, publication date: April 18, 2013)

An object of the present invention is to provide a superconducting power device in which a shielding ring is installed to mitigate the electric field of a triple point of a superconducting power device, but the shielding has a double curvature structure to enable the most effective electric field relaxation. To provide.

According to the features of the present invention for achieving the object as described above, the present invention provides a superconducting element accommodated in a cooling tank filled with a refrigerant, and an insulation installed inside the cooling tank to insulate the superconducting element apart from the cooling tank. It includes a structure and a metal shielding ring installed to mitigate an electric field on a surface having a triple point of the insulating structure.

The metal shielding has a curved portion that covers or hides the triple point of the insulating structure, wherein the curved portion has at least one concave inflection point, and is divided into a plurality of curved portions having a different radius of curvature based on the inflection point. It is a metal shield ring.

The electric field relaxation by the double curvature metal shielding satisfies a distance condition of (B)-(T) ≤ (A)-(T).

[Here, (A) is the inflection point, (B) is the surface with the triple point, and (T) is the tangent line of the maximum protrusion of the curved portion far from the triple point.]

In the double-curvature metal shielding ring, two metal shielding rings having different curvatures of a curved portion are attached to each other up and down so that one supports the insulating structure and the other performs electric field relaxation.

When the double-curvature or multi-curvature metal shielding ring is installed on the surface of the insulating structure with the triple point, the electric field concentrated on the surface of the triple point is 10 kV/mm or less.

The present invention improves the electric field relaxation effect by dispersing an electric field concentrated at the triple point by installing a double curvature metal shielding ring at the end of an insulating structure where a triple point occurs in a superconducting power device.

Therefore, it is possible to remove the risk of insulation breakdown of the insulating structure, thereby improving the safety of the superconducting power device, and reducing the size of the power device by increasing the insulation effect, enabling the design of economical and compact superconducting power devices. It works.

1 is a view showing the inside of a cooling tank of a superconducting power device.
FIG. 2A is a view showing an insulating structure, and FIG. 2B is a view showing a voltage distribution in a portion where the insulating structure RFP of FIG. 2A, a refrigerant (liquid nitrogen), and a support part SUS contact each other.
3 is a view showing a state in which a double curvature metal shield ring is installed in a superconducting power device according to the present invention.
Figure 4 is a side view showing a state in which a double curvature metal shielding ring is installed at an end of an insulating structure according to an embodiment of the present invention.
5 is a view showing a voltage distribution when a double curvature metal shielding ring is installed to satisfy a distance condition of (B)-(T) ≤ (A)-(T) in an embodiment of the present invention.
6 is a diagram showing a voltage distribution when a double curvature metal shielding ring is installed to satisfy the (B)-(T) distance> (A)-(T) distance condition as an embodiment of the present invention.
7 is a view showing a double curvature metal shielding ring according to another embodiment of the present invention.
8 is a diagram showing a voltage distribution when FIG. 7 is applied to an insulating structure of a superconducting fault current limiter.
9 is a view showing a double curvature metal shielding ring according to another embodiment of the present invention.
10 is a diagram showing a voltage distribution when FIG. 9 is applied to an insulating structure of a superconducting current limiter.
11 is a view showing voltage distribution when a single curvature metal shielding ring is applied to an insulating structure of a superconducting current limiter as Comparative Example 1. FIG.
12A and 12B are diagrams showing a voltage distribution when a metal structure is applied to an insulating structure of a superconducting current limiter as Comparative Example 2;

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

In the superconducting power device of the present invention, a shield ring is installed to mitigate the electric field of a triple point, but a double curvature shield ring is installed to enable the most effective electric field relaxation.

Specifically, as shown in FIG. 3, the superconducting power device includes a superconducting element 13 accommodated in a cooling tank 10 filled with a refrigerant 11 and a superconducting element installed inside the cooling tank 10. An insulating structure 15 that separates 13) from the cooling tank 10 to insulate it, and a metal shield ring 17 installed on a surface of the insulating structure 15 where the triple point S is to mitigate an electric field.

The superconducting element 13 is accommodated in the cooling tank 10 in the form of a superconducting coil wound around an insulating material. The insulating material may be formed in a mesh shape for securing a flow path of the refrigerant and for smooth contact between the superconducting coil and the refrigerant. A high voltage is applied to the superconducting element 13.

The cooling tank 10 may include an inner container filled with a refrigerant and an outer container that surrounds the outer surface of the inner container and forms a heat insulating layer between the inner container.

The refrigerant 11 may correspond to liquid nitrogen or liquid helium.

The insulating structure 15 secures dielectric strength and mechanical strength, and at the same time reduces the volume of the cooling tank 10, thereby enabling the manufacture of a compact superconducting power device. When the insulating structure 15 is used, the insulating distance can be reduced compared to the case where only the refrigerant 11 is filled in the cooling tank, so that the volume of the cooling tank 10 can be reduced.

The insulating structure 15 is preferably made of a fiber-reinforced plastic (FRP) material. Fiber-reinforced plastic material has higher tensile strength and lighter weight than plastic, and has excellent electrical insulation performance at cryogenic temperatures, making it easy to use as an insulating structure.

However, the insulating structure 15 may be made of any one of PPLP, Tyvek, insulating paper, polyimide, and Kapton.

The insulating structure 15 may have a round cylindrical shape and a plurality of insulation structures 15 may be installed between the cooling tank 10 and the superconducting element 13.

A support part 10a made of SUS material may be further installed at the end of the insulating structure 15. The support 10 serves to fix the insulating structure 15 to the cooling tank 10.

The shielding ring uses a metal shielding ring 17 to perform two functions of mitigating the electric field at the triple point S and fixing the insulating structure 15.

The metal shielding ring 17 may be manufactured in a ring shape and fitted into the outer surface of the insulating structure 15, or may be manufactured in a ring shape with a closed bottom surface and be fitted into the outer surface while surrounding the end of the insulating structure 15. .

The end of the insulating structure 15 becomes a surface with (occurs) a triple point (S). The triple point S is a contact point between three types of different substances (or three phases of substances), and the insulating structure 15, the refrigerant 11, and the support 10a (or the cooling tank 10) come into contact with each other.

When the metal shielding ring is installed, the triple point is a contact point where the insulating structure 15, the coolant 11, and the metal shielding ring 17 come into contact.

The metal shielding ring 17 prevents the electric field from concentrating at the contact point of the three phases of the material by adjusting the angle where each structure meets at the triple point.

The metal shielding ring 17 is preferably a double-curvature metal shielding ring or a multi-curvature metal shielding ring. The multi-curvature metal shielding ring includes triple curvature and quadruple curvature metal shielding rings.

The metal shielding ring 17 may be made of a metal material such as SUS, aluminum, or aluminum alloy.

In one embodiment, as shown in Figure 4, the double-curvature or multi-curvature metal shielding ring 17 is provided with a curved portion 18 to cover or hide the triple point of the insulating structure 15, the curved portion 18 By having at least one inflection point (A) concave in the inflection point (A) has a structure divided into a plurality of curved portions (18a, 18b) having different radius of curvature based on the inflection point (A).

When divided into two curved portions based on the inflection point A, the two curved portions may be referred to as a first curved portion 18a and a second curved portion 18b.

The two curved portions of the double curvature metal shielding ring 17 with different curvature radii can disperse the electric field concentrated at the triple point by adjusting the contact angle of the insulating structure (FRP), refrigerant (liquid nitrogen), and double curvature metal shelling ring (SUS). have.

When designing a metal shielding ring with a single curvature, the insulating structure and the metal shielding ring should be closely attached to each other to support the insulating structure. In this case, machining tolerances or gaps that are not actually visible to the eye occur, and the electric field concentration between the insulating structure and the metal shielding cannot be alleviated.

However, the electric field mitigation effect may be achieved by increasing the radius of the curved portion of the metal shield ring, but since the radius becomes larger than the limited space, manufacturing and installation are difficult.

Therefore, the electric field concentrated in the triple point is dispersed by adjusting the contact angle by designing the curved portion of the metal shield ring with a double curvature.

As for the electric field relaxation by the double-curvature metal shielding, as shown in FIG. 5, it is preferable to satisfy the distance condition of (B)-(T) ≤ (A)-(T).

Here, (A) is an inflection point, (B) is a surface with a triple point, and (T) is a tangent line of the maximum protrusion of the curved portion (second curved portion 18b) at a position far from the triple point.

When the double-curvature metal shielding ring is installed on the surface (B) with the triple point of the insulating structure 15, and the distance condition of (B)-(T) ≤ (A)-(T) is satisfied, Fig. As a result of performing the same calculation as in the calculation conditions of 2a and 2b, the electric field relaxation effect was confirmed as 4.0 kV/mm or less.

If the distance condition of (B)-(T) ≤ (A)-(T) is not satisfied, that is, if the distance of (B)-(T)> (A)-(T) condition is satisfied, the electric field dispersion The effect is a little low. This means that even if the double curvature is applied, the electric field dispersion effect is slightly lower than when the distance condition of (B)-(T) ≤ (A)-(T) is satisfied.

In another embodiment, the double-curvature metal shielding ring may have a structure in which a curved portion is formed only on an upper surface, and the curvature of the curved portion is divided into two curved portions having a different radius of curvature based on the inflection point.

In another embodiment, the double-curvature metal shielding ring may be formed by attaching two metal shielding rings having different curvatures of a curved portion to each other, or two metal shielding rings having different curvatures of the curved portion disposed adjacent to each other.

For example, among the two metal shielding rings, a metal shield ring having a small radius of curvature fixes the insulating structure, and a metal shield ring having a large radius of curvature performs electric field relaxation of the triple points of the insulating structure.

Hereinafter, one embodiment, another embodiment, and another embodiment of the present invention will be described in comparison with Comparative Examples 1 and 2.

<One Example>

FIG. 5 shows an electric field concentrated at a triple point in a superconducting current limiter among superconducting power devices being dispersed by a double curvature metal shield ring.

5 is a design of a double curvature metal shielding ring to satisfy a distance condition of (B)-(T) ≤ (A)-(T). Here, (A) is an inflection point, (B) is a surface with a triple point, and (T) is a tangent line of the maximum protrusion of the curved portion (second curved portion 18b) at a position far from the triple point.

As shown in FIG. 5, it is confirmed that the electric field concentrated at the triple point is dispersed along the curvature when compared with FIG. 2B.

In addition, as a result of performing the same calculation as in the calculation conditions of FIGS. 2A and 2B, the electric field relaxation effect was confirmed as 4 kV/mm or less.

Through this, if the double curvature metal shielding ring is installed to satisfy the distance condition of (B)-(T) distance ≤ (A)-(T) at the end of the insulating structure where the triple point occurs, the double curvature metal shielding ring becomes a triple point. It can be seen that the effect of electric field relaxation is large by dispersing the electric field concentrated in.

On the other hand, FIG. 6 shows that the electric field concentrated at the triple point in the superconducting current limiter among the superconducting power devices is dispersed with a double-curvature metal shielding ring, but the double-curvature metal shielding ring is the distance between (B)-(T)> (A)-(T ) To satisfy the condition.

Here, (A) is an inflection point, (B) is a surface with a triple point, and (T) is a tangent line of the maximum protrusion of the curved portion (second curved portion 18b) at a position far from the triple point.

As shown in FIG. 6, compared with FIG. 2B, it is confirmed that the electric field concentrated at the triple point is dispersed along the curvature, but it is confirmed that the electric field is partially concentrated at the triple point.

In addition, as a result of performing the same calculation as in the calculation conditions of voltages Figs. 2A and 2B, the electric field relaxation effect is E (electric field) max = 4.5 kV/mm, and the electric field relaxation effect is the distance between (B)-(T)> (A)-(T) It can be seen that it is slightly lower than when the condition is satisfied.

Through this, it can be confirmed that even if a double-curvature metal shielding ring is installed at the end of the insulating structure where the triple point occurs, it is important to satisfy the distance condition of (B)-(T) ≤ (A)-(T). have.

<Another Example>

In the double-curvature metal shielding ring of another embodiment, as shown in FIG. 7, a curved portion is formed only on an upper surface, and the curvature of the curved portion is divided into two curved portions having different radii of curvature based on the inflection point.

FIG. 8 is a measurement of voltage distribution by applying FIG. 7 to a superconducting fault current limiter among superconducting power devices.

As shown in FIG. 8, it is confirmed that the electric field concentrated at the triple point is dispersed along the curvature when compared with FIG. 2B.

Through this, it can be confirmed that the double curvature metal shielding has an effect of mitigating the electric field by dispersing the electric field concentrated in the triple point even if the double curvature is formed only on the upper surface.

<Another Example>

The double-curvature metal shielding ring of another embodiment is formed by connecting two metal shielding rings having different curvatures of a curved portion up and down, or two metal shielding rings having different curvatures of a curved portion, as shown in FIG. 9. It can be arranged and formed.

In the case of Fig. 9, A becomes an inflection point, and B becomes a curved portion at a position far from the triple point.

FIG. 10 is a measurement of voltage distribution by applying FIG. 9 to a superconducting current limiter among superconducting power devices.

As shown in FIG. 10, it is confirmed that the electric field concentrated at the triple point is dispersed along the curvature when compared with FIG. 2B.

Through this, it can be seen that the double curvature metal shielding has an effect of mitigating the electric field by dispersing the electric field concentrated at the triple point even if two metal shielding rings having different curvatures of the curved portion are attached to each other or disposed adjacent to each other.

In such a double curvature metal shield ring, the lower metal shield ring supports the insulating structure, and the upper metal shield ring serves to relieve the electric field.

<Comparative Example 1>

In Comparative Example 1, a single curvature metal shielding ring was applied to a superconducting current limiter to measure the voltage distribution.

As shown in Fig. 11, even if the radius of the curved portion of the single-curvature metal shield ring was increased, the electric field concentrated in the interval a was not relaxed with the gentle curved portion.

The gap a is the gap between the insulating structure and the metal shielding ring, and is formed by processing tolerances or gaps that are not visible during actual manufacturing.

In addition, as a result of performing the same calculations as those of Figs. 2A and 2B, E (electric field) = 5.0 kV/mm was calculated.

<Comparative Example 2>

In Comparative Example 2, a metal structure for concentrating an electric field inside an insulating structure was formed without a metal shielding ring.

12A is a case where there is no gap by melting an insulating material such as epoxy between the insulating structure and the metal structure, and FIG. 12B is a case where there is a gap between the insulating structure and the metal structure.

12A and 12B, when there is no gap between the insulating structure and the metal structure, the internal Emax value was calculated as 4.8kV/mm, and when there is a gap between the insulating structure and the metal structure, the triple point Emax value is 5.3. It was calculated as kV/mm and the internal Emax value was calculated as 15 kV/mm.

In particular, when there is a gap between the insulating structure and the metal structure, the electric field value further increased.

Through this, it can be confirmed that it is difficult to reduce the electric field even if a metal structure for concentrating the electric field inside the insulating structure is formed without a metal shielding ring.

Through computational simulation and experimental experience comparing the examples and comparative examples, it can be confirmed that installing a double curvature metal shielding ring at the end of the insulating structure where the triple point occurs has an effect of mitigating the electric field by dispersing the electric field concentrated at the triple point. have.

Moreover, when the double-curvature metal shielding ring satisfies the distance condition of (B)-(T) distance ≤ (A)-(T), the double-curvature metal shielding ring disperses the electric field concentrated at the triple point to relieve the electric field. You can see that the effect is best.

The scope of the present invention is not limited to the embodiments described above, but is defined by what is described in the claims, and it is obvious that a person having ordinary knowledge in the technical field of the present invention can make various modifications and adaptations within the scope of the claims. Do.

10: cooling tank 11: refrigerant
13: superconducting element 15: insulating structure
17: (double curvature) metal shielding 18: curved part
18a: first curved portion 18b: second curved portion
A: inflection point S: triple point

Claims (5)

A superconducting element accommodated in a cooling tank filled with a refrigerant;
An insulating structure installed inside the cooling tank to insulate the superconducting element from the cooling tank by being separated from the cooling tank;
Including a metal shield ring installed to mitigate an electric field on a surface of the insulating structure with a triple point,
The metal shielding ring,
Provided with a curved portion covering or hiding the triple point of the insulating structure,
The curved portion is a double-curvature or multi-curvature metal shielding ring having at least one concave inflection point and divided into a plurality of curved portions having a different radius of curvature based on the inflection point. delete The method according to claim 1,
The electric field relaxation by the double curvature metal shield ring,
A superconducting power device, characterized in that it satisfies a distance condition of (B)-(T) ≤ (A)-(T).
[Here, (A) is the inflection point, (B) is the surface with the triple point, and (T) is the tangent line of the maximum protrusion of the curved portion far from the triple point.] The method according to claim 1,
The double curvature metal shield ring
It is formed by attaching two metal shield rings with different curvatures of the curved part to each other,
A superconducting power device, characterized in that one supports the insulating structure and the other performs electric field relaxation. The method according to claim 1,
Superconducting power device, characterized in that when the double-curvature or multi-curvature metal shielding ring is installed on the surface of the insulating structure with the triple point, the electric field concentrated on the surface with the triple point is 10 kV/mm or less.

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