KR101749814B1 - Superconducting fault current limiting element protecting device - Google Patents

Abstract

The present invention relates to a device for protecting a superconducting fault current element, comprising a plurality of serially connected superconducting fault current elements, a plurality of corona rings having one end connected to one end of each superconducting fault current element, And a shunt resistance unit for connecting the other ends of the superconducting fault current elements and the respective corona rings in a parallel form to detect the current input to the superconducting fault current elements.

Description

TECHNICAL FIELD [0001] The present invention relates to a superconducting fault current protection device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for protecting a superconducting fault current element, and more particularly, to a superconducting fault current element protecting apparatus for connecting a corona ring to both ends of a superconducting fault current element to perform a role of a shunt resistance.

In the resistance type current limiting device, the superconducting current limiting device restricts the fault current by using the normal transition phenomenon called the quench of the superconductor. In order to apply a resistance-type current limiting element to a real system, one superconducting wire or one superconducting module can not cope with all the voltages and currents. Therefore, it is necessary to increase the capacity through serial-parallel connection of the unit modules. In this case, even if the resistance of the module is different from that of the parallel connection, there is no big problem because the current distribution occurs in a direction to relax the current concentration. However, in the case of voltage distribution, if the characteristics between the modules are different, it occurs in the direction of accelerating the voltage concentration. Therefore, a method is needed to protect the superconducting current limiting device and to increase the capacity of the current limiting device.

In general, in high-voltage power equipment, a corona ring is used as a method for securing insulation of a device by relieving a strong electric field generated by a high voltage. The superconducting current-limiting device is also a high-voltage power device, and the superconducting wire is a thin tape-like wire. Even if the module is formed into a circular shape or an elliptical shape, a corona ring shape is necessarily existent.

In this regard, Korean Patent Laid-Open Publication No. 2010-0079670 discloses a "modular current limiting device for a matrix type superconducting current-limiting device ".

SUMMARY OF THE INVENTION It is an object of the present invention to provide a device for protecting a superconducting superconducting fault element, which is connected to one end of a superconducting fault current limiting element and serves as a shunt resistor.

It is also an object of the present invention to provide a superconducting fault current limiting device that adjusts a resistance value based on a resistivity value, a cross-sectional area, and a length depending on a radius of a corona ring of a corona ring material.

Another object of the present invention is to provide a superconducting fault current limiting device for changing the sectional area of a connecting line for electrical connection between a superconducting fault current limiting device and a corona ring.

According to an aspect of the present invention, there is provided an apparatus for protecting a superconducting fault current limiting device comprising: a plurality of superconducting fault current limiting devices connected in series; A plurality of corona rings, one end of which is connected to one end of each superconducting current-limiting element; And a shunt for connecting the other end of each of the superconducting fault current elements and the other end of each of the respective corona rings to connect each of the superconducting fault current elements and each of the corona rings in parallel form to detect a current input to the superconducting fault current element shunt resistance portion.

The plurality of corona rings are characterized in that the resistance value is adjusted based on a resistivity value of the material, a cross-sectional area, and a length depending on the radius of the corona ring.

The plurality of corona rings are formed of carbon fibers.

In addition, the shunt resistor portion may be formed of at least one of a braided wire and a copper block.

The device for protecting a superconducting fault current limiting device according to the present invention having the above-described structure can effectively prevent an electric field and improve a voltage unbalance by connecting one corona ring to both ends of the superconducting fault current limiting device, .

Further, the present invention has an effect of generating an optimum resistance value for protecting the superconducting fault current element by adjusting the resistance value based on the resistivity value, the cross-sectional area, and the length depending on the radius of the corona ring of the corona ring material.

In addition, the present invention has an effect of increasing the cross-sectional area of a connection line for electrical connection between the superconducting fault current element and the corona ring, thereby inducing voltage equalization.

1 is a view for explaining a corona ring applied to a superconducting superconducting superconductor.
2 is a circuit diagram of a superconducting fault current limiting device according to the present invention.
3 is a view for explaining the calculation of the resistance range of the corona ring applied to the present invention.
4 is a view for explaining an example of application of the superconducting fault current limiting device according to the present invention.
Fig. 5 is a diagram showing an experimental result of Fig. 4. Fig.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to facilitate a person skilled in the art to easily carry out the technical idea of the present invention. . First, in adding reference numerals to the constituent elements of the drawings, it should be noted that the same constituent elements are denoted by the same reference numerals whenever possible even if they are displayed on other drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

1 is a view for explaining a corona ring applied to a superconducting superconducting superconductor.

Referring to FIG. 1, the corona ring can not be fabricated with one ring because of the operation characteristics of the superconducting fault current element. In the case of a superconducting fault current device, the electric field can be mitigated by a single corona ring because of the equal voltage. However, when a fault current is generated and a current of the superconducting fault current device is limited, a potential difference occurs between the devices. Due to the possibility of dielectric breakdown due to the potential difference between the current-limiting device and the corona ring, the number of the devices must be separated and manufactured in series.

Therefore, the present invention aims at inducing equipotential distribution of a superconducting fault current element through simple circuit modification without changing the shape and structure of a conventional superconducting fault current element.

2 is a circuit diagram of a superconducting fault current limiting device according to the present invention.

2, the superconducting fault current limiting device 100 according to the present invention includes a plurality of superconducting fault current limiting devices 110, a plurality of corona rings 120, and a shunt resistance portion 130 .

A plurality of superconducting current-limiting elements 110 are connected in series.

A plurality of corona rings (120) are connected at one end to one end of each superconducting current limiting element (110).

The plurality of corona rings 120 can adjust the resistance value based on the resistivity value, the cross-sectional area, and the length of the corona ring of the material to induce voltage equalization of the superconducting fault current limiter 110. This will be described in detail later with reference to FIG. The connection line connecting one end of the plurality of corona rings 120 and one end of the plurality of superconducting fault current limiting devices 110 is made of a very thin wire for electrical connection.

The shunt resistor unit 130 is connected to the other end of each of the superconducting fault current elements 110 and the other end of each of the corona rings 120. At this time, the shunt resistor unit 130 is preferably formed using a braided wire or a copper block having a large cross-sectional area in order to flow a current.

The shunt resistor unit 130 connects the respective superconducting fault current elements 110 and the respective corona rings 120 in a parallel form to detect a current input to the superconducting fault current element 110.

Here, the shunt resistor is a kind of shunt resistor, which is a resistor mainly used for current measurement, and is basically a resistor having a very low resistance value. It is also called a classifier, which means to divide the current. The main purpose of using a shunt resistor is to measure the current. It is a method of measuring the current, measuring the voltage generated in the resistor by inserting the resistor in series between the current-carrying wires.

3 is a view for explaining the calculation of the resistance range of the corona ring applied to the present invention.

Referring to FIG. 3, the resistance value of the corona ring according to the present invention is determined by the following equation (1).

here,

The corona ring is the resistivity value of the material,

Sectional area of the corona ring,

Is the length of the corona ring (

Is a constant determined by the radius to minimize the electric field according to the size of the cryogenic vessel and the superconducting current-limiting device), and the radius of the corona ring

When you say

silver

to be.

Accordingly, the range of the corona resistance resistance value according to the present invention is determined as follows.

The length of the corona ring

And the magnitude of the resistance is

Is determined by the following equation (2).

Range of

Because of,

The range is

.

As described above, the corona ring according to the present invention can generate a wide range of resistance based on various material changes, cross-sectional areas, and various superconducting fault current limiting lengths within the range, thereby generating an optimum resistance for protection of superconducting fault current devices.

FIG. 4 is a view for explaining an application example of a superconducting fault current limiting device according to the present invention, and FIG. 5 is a diagram showing an experimental result of FIG.

4, when it is assumed that a superconducting wire having a stabilizer is used to design a 154 kV superconducting superconducting element in series connection of six superconducting superconducting current modules composed of four parallel superconducting wires, Voltage, generated resistance), the resistance of the superconducting current-limiting module is about 1 ohm.

Here, if the magnitude of the shunt resistor is set at about 80% of the normal-conduction resistance, the resistance of the corona ring for voltage equalization is 0.8 ohm (ref. Shunt-assisted simultaneous quenches in series-connected resistive SFCL components).

Considering the size of the superconducting current-limiting device, assuming that the radius of the corona ring is about 0.8 m and the cross-sectional area is 2500 mm 2, the resistivity of the corona ring material is 1.6 e-3 [Ωm].

The material satisfying this is carbon fiber. Since carbon fiber is of a material quality and has a high burning temperature, it can maintain its shape even when a current flows through the corona ring, and is most preferable as a material for corona ring.

In order to verify the possibility of voltage distribution using the corona ring according to the present invention, the maximum current passing through the carbon fiber should be 10 A / mm 2 or more.

Fig. 5 is a short-circuit test result using such a carbon fiber. A current of about 200 A or more was passed through the carbon fiber having a cross-sectional area of about 5 mm ² , but no damage occurred at all.

This can be said to be effective as a corona ring material because the carbon fiber can flow a maximum current of about 40 A / mm ² or more.

As described above, in the superconducting fault current limiting device protection device according to the present invention, one corona ring is connected to both ends of the superconducting fault current limiting device to perform the role of the shunt resistor, so that the electric field can be effectively mitigated and the voltage unbalance can be improved.

Further, the present invention can produce an optimum resistance value for protection of the superconducting fault current element by adjusting the resistance value based on the resistivity value of the corona ring material, the cross-sectional area, and the length depending on the radius of the corona ring.

Further, the present invention can increase the cross-sectional area of the connection line for electrical connection between the superconducting fault current element and the corona ring to induce voltage equalization.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but many variations and modifications may be made without departing from the scope of the present invention. It will be understood that the invention may be practiced.

100: Superconducting current limiting element protection device
110: Superconducting current-limiting element
120: Corona ring
130: Shunt resistance part

Claims (4)

A plurality of superconducting current-limiting elements connected in series;
A plurality of corona rings, one end of which is connected to one end of each superconducting current-limiting element; And
And the other end of the superconducting fault current element is connected to the other end of the corona ring connected to the other end of the superconducting fault current element to connect the superconducting fault current element and the corona ring in parallel, A shunt resistor for detecting the shunt;
Wherein the superconducting fault current limiting device comprises: The method according to claim 1,
Wherein the resistance values of the plurality of corona rings are adjusted based on a resistivity value of the material, a cross-sectional area thereof, and a length depending on a radius of the corona ring. The method according to claim 1,
Wherein the plurality of corona rings are formed of carbon fibers. The method according to claim 1,
Wherein the shunt resistor part comprises at least one of a braided wire and a copper block.

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