JPH10116743A - Superconducting current limiter introduced with air gap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the control impedance of an electric apparatus from decreasing by coupling a closed magnetic path including an air gap and a closed magnetic path including no air gap in parallel with a primary winding short-circuited with a superconductor. SOLUTION: A superconductor 2 short-circuited as a secondary winding on the inside is wound around the one side leg part 1A of a core 1 having an air gap A and a primary winding 3 is wound on the outside thereof. A superconducting current limiter 10 is constituted by winding the superconductor 2 and the primary winding 3 thereby coupling a general magnetic path, i.e., a short-circuited magnetic path 4, and a magnetic path 5 including the air gap A in parallel, in the sense of magnetic circuit, with the primary winding 3. When a fault current flows, the current flowing through the primary winding 3 increases and flows through the secondary winding, i.e., the superconductor 2, to generate a resistance exceeding the critical value of the superconductor 2. Consequently, an impedance for limiting the fault current is generated for an extremely short time and a switching function for limiting the current can be provided using superconducting characteristics without requiring any additional controller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting current limiting device having an air gap.
The present invention relates to a superconducting current limiting device that utilizes a characteristic of a superconductor without providing an external control device, and in particular, improves a current limiting performance by using a damping coil.

[0002]

2. Description of the Related Art Magnetic elements, inductors and transformers are indispensable elements among many electric devices.
It has been widely used in the past. The magnetic and electrical properties of such electrical device materials have a significant effect on the design and fabrication of inductors and electrical equipment. In other words, various components that use magnetic properties are price, volume, weight,
It is designed in consideration of various factors such as difficulty of production. Therefore, an effective design based on the principle governing the characteristics of the magnetic element is required.

[0003] A superconducting current limiting device, which is a type of magnetic element, is capable of supplying high-quality power and preventing high fault current or transient current (TRANSIENT CURRENT) from flowing to electric elements of a power system. Developed and proposed for purpose. An ideal superconducting current-limiting device should have a small effect on the power system under normal conditions, while in the event of an accident, it needs a sufficient increase in impedance to limit the fault current. However, some prototypes of high-temperature superconducting current-limiting devices using magnetic materials have a magnetic core (Magnetic Core).
As a result, the impedance is reduced by the saturation of e). In general, such a saturation problem can be solved by designing the flux linkage of the inductor in a normal state to be doubled. However, this has the problem of increasing the size and weight of the superconducting current limiting device (or inductor) and increasing the price.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a new inductor capable of preventing a decrease in control impedance in electric equipment and superconducting current limiting equipment. That is, the introduction of an effective air gap and the proper design of the core, such as a shorted superconductor or a shorted general conductor, to prevent core saturation by proper design. It is in.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention has a structure in which two magnetic circuits are connected in parallel, that is, it has a plurality of legs, at least one of which has a plurality of legs. In a superconducting current limiting device having an iron core in which a gap capable of preventing saturation is formed in one leg, a primary winding and a short-circuited superconductor are wound around a leg of the core, and the gap is included. Between the closed magnetic path and the closed magnetic path including the air gap,
It is a fundamental feature that the secondary winding is connected in parallel with a magnetic circuit. With this configuration, the superconducting current limiting device of the present invention limits the fault current by the inductance of the magnetic path without a gap at a low operating voltage and current, and the fault current by the inductance of the magnetic path with a gap at a high operating voltage and current. Can be restricted.

In general, when a core having no air gap is used, the maximum energy must be increased four times as a design condition in order to prevent saturation, so that the volume of the inductor is also increased four times. Become.

In order to solve this problem, the present invention is to connect two magnetic circuits in parallel. Of course,
The number of leg portions having a gap and the leg portion without a gap can be plural, and various combinations are possible, and a plurality of damping coils can be combined. The transformer and the inductor having the magnetic circuit connected in parallel in this way can have a wider operating voltage. The characteristics and principle of this are the same as those of the superconducting current limiting device,
In order to improve this characteristic, the present invention provides a superconductor (winding or damping coil) short-circuited to a gap leg.
Alternatively, a short-circuited general conductor (winding or damping coil) is provided. In the above, the damping coil can be defined as a shorted conductor,
When the inductor or the transformer in which it is installed has almost no change in inductance, when the secondary coil of the transformer is opened in such a form, it operates as an inductor.

The present invention more specifically relates to a primary winding {a general conductor winding or a superconductor (winding)} and a secondary winding (a short-circuited superconductor (winding) or An open general conductor winding or an open superconductor winding) is connected in parallel in a magnetic circuit with an iron core having three legs. In the above, one leg is the leg on which the winding is located, and the center leg has a gap introduced. A primary copper winding is connected in series to the power line to protect the circuit elements. In a normal state, the magnetic flux is canceled by the current induced in the superconductor, so that the impedance is very low and the impedance is dependent on the primary winding resistance and the leakage inductance. If the superconductor exceeds the critical current at the time of the accident, a flux flow resistance occurs in the superconductor, and the magnetic flux in the iron core increases rapidly. If magnetic saturation occurs, the magnetic resistance of the magnetic path including the air gap becomes much smaller than the magnetic resistance of the magnetic furnace including no air gap. Therefore, the magnetic flux flows to the air gap side where the magnetic resistance is small, which prevents a sudden decrease in impedance at the time of saturation, so that the current limiting effect can be greatly increased. In the present invention,
Explaining the iron core structure, if the iron core has no air gap, saturation will occur earlier on the magnetization curve (BH). However, if an air gap is formed in the iron core, the short-circuited magnetic path and air gap Since the paths are connected in parallel to form a slow curve on the magnetization curve, saturation will occur slowly. Therefore, the magnetization control range can be greatly improved, and the damping coil is provided in this gap to further enhance the effect.

The present invention includes various forms. An example is as follows. 1) When the superconductor short-circuited with the primary winding is wound around different legs, respectively, the primary winding is wound inside the same leg and the superconductor is wound outside the same. When the superconductor is wound inside the same leg and the primary winding is wound outside the same leg, the primary winding is wound around the same leg. This includes any case where the superconductor is wound alternately with the superconductor. 2) Also, the air gap may be formed outside the iron core, the primary winding may be provided inside the one leg, and the short-circuited superconductor may be provided outside. 3) A short-circuited conductor or a short-circuited superconductor may be located in a parallel magnetic path other than the magnetic path formed by the primary winding. 4) A gap may be formed outside the iron core, and a short-circuited conductor or a short-circuited superconductor may be located in a parallel magnetic path other than the magnetic path formed by the primary winding. 5) In order to combine a plurality of magnetic circuits connected in parallel, a plurality of gaps may be combined and a plurality of damping coils may be combined. 6) An open superconductor or an open general conductor winding or no winding is provided inside one leg of the iron core having an air gap, and a general conductor winding or superconductor is provided outside the opening. The secondary winding may be provided and a general conductor winding short-circuited to a parallel magnetic path other than the magnetic path formed by the primary winding or a superconductor short-circuited may be provided and used as an inductor. 7) A superconductor or an open general conductor winding as a secondary side is provided inside one leg of the iron core having an air gap, and a general conductor winding or superconductor is provided outside the opening. A general conductor winding short-circuited or a superconductor short-circuited may be installed in a parallel magnetic path other than the magnetic path in which the primary winding can be installed by using the secondary winding, and used as a transformer.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.
This will be described specifically. [First Embodiment] = FIG. 3 FIG. 3 shows an example in which one side leg 1 </ b> A of the iron core 1 having a gap A is provided.
The superconductor 2 short-circuited as a secondary winding is wound inside,
A primary winding 3 is wound around the outside. Due to the winding of the superconductor 2 and the primary winding 3, the short-circuited magnetic path 4 as a general magnetic path and the magnetic path 5 including the air gap A are moved relative to the primary winding 3. The superconducting current limiting device 10 is configured by being connected in parallel in a magnetic circuit. The superconductor 2 may be in any form such as a linear body or a plate-like body. The linear body and the plate-like body each include those obtained by molding powdery materials.

Although the gap A is single in this embodiment, a plurality of gaps can be combined, a plurality of magnetic circuits connected in parallel can be combined, and a plurality of damping coils can be combined. Can be. Further, the positions of the primary winding 3 and the superconductor (winding) 2 inside and outside may be changed, or the primary winding 3 and the superconductor (winding) 2 may be separately arranged vertically and alternately arranged. Leg 1
C can be separately installed. In the above description, the main magnetic path 4 is a magnetic path passing through the primary winding 3, and the parallel magnetic path 5 is formed by several air gaps A or several legs (primary winding 3).
(Other than the legs on which the is installed). That is, if the main magnetic path 4 is a magnetic path passing through the leg 1A, the parallel magnetic path 5
Is a magnetic path passing through the leg 1B or the leg 1C. In addition, the length of the air gap A, the length of the magnetic path, and the cross-sectional area of the magnetic path can be appropriately changed to adjust the magnetic resistance. In addition, one or several damping coils 6 can be installed in the parallel magnetic path. In the above, the primary winding 3 may use any of a superconductor and a general conductor winding, and the superconducting current limiting device 10 is connected in series to the electric circuit to protect the electric circuit. Connect. The secondary winding 2 uses a short-circuited superconductor (winding).

In any case, the superconducting current limiting device 10 configured as described above is applied to a circuit of a power system as shown in FIG. Even without help, the fault current can be sensed by itself and the fault current can be limited.

Next, the specific operation will be described.
If the current is supplied to the circuit of the power system in a normal state, it means that the superconductor 2 is within the critical value as shown in FIG. That is, the magnetic field H created outside
A current is generated in a direction in which the magnetic field H is to be eliminated.
(Zero). Accordingly, the inductance becomes almost zero and the voltage drop is eliminated, so that no interruption is caused to the current flow. Therefore, in the normal state, the superconductor 2
The magnetic flux cannot enter the iron core 1 due to the magnetic flux canceling effect or the magnetic shielding effect. Since the impedance at this time is only the leakage impedance and the resistance of the primary winding 3, the current normally flows into the circuit of the power system. It will flow.

If an accident current flows, the load resistance (R _L ) in FIG. 2 becomes 0 and the current increases, so that the current of the primary winding 3 increases and 2 It is guided by the superconductor 2 which is the secondary winding, thereby exceeding the critical value of the superconductor 2 and generating a resistance. Therefore, FIG.
Is not generated, and the inductance L increases. Therefore, a voltage drop occurs due to an increase in the inductance L, and an impedance for limiting the fault current is generated in a very short time, and the fault current is controlled by using the superconducting characteristic without requiring a separate control device. It has a switching function to limit the current. That is, at the time of an accident, the current induced in the superconductor 2 exceeds the critical current of the superconductor and the magnetic flux cancels out or the magnetic shielding effect of the superconductor is lost. This leads to an increase in

The magnetic flux that has passed through the iron core 1 is
When the maximum magnetic flux density reaches
Without passing through the magnetic path 5 including the air gap A. This is because the magnetic resistance of the short-circuited magnetic path 4 at the time when saturation occurs becomes larger than the magnetic resistance of the magnetic path 5 including the air gap A, so that the magnetic flux selects the magnetic path 5 including the air gap A. It depends. That is, the iron core 1 including the gap A not only generates saturation later than the iron core having no gap, but also causes saturation at a high current, so that the following relationship is established. If the iron core that does not include the gap A is not saturated, the magnetic resistance (including the gap)> the magnetic resistance (not including the gap). When the iron core that does not include the air gap is saturated, the magnetic resistance (including the air gap) <the magnetic resistance (not including the air gap). As described above, saturation is prevented by moving the flow of the magnetic flux toward the magnetic path 5 including the air gap A, thereby preventing the impedance from decreasing. Therefore, the fault current can be more easily limited. It is.

[Second Embodiment] = FIG. 4 In this embodiment, as shown in FIG.
Was changed not to the center but to the outer leg 1B, and at the same time, the primary winding 3 was wound inside the one leg 1A opposite to the leg 1B and short-circuited outside. Superconductor 2
Has been wound. The other parts are the same as those of the first embodiment, the same parts are denoted by the same reference numerals, and the operation is the same, so that the description is omitted.

[Third Embodiment] = FIG. 5 In this embodiment, as shown in FIG. 5, a damping coil, that is, a short-circuited general conductor winding or a short-circuit is provided on a central leg 1B having a gap A. The superconductor or the short-circuited superconductor winding 6 is positioned so that saturation is not generated by the magnetic flux canceling effect. That is, even if the iron core 1 has the gap A, it is natural that saturation occurs when the strength of the magnetic field increases, but the superconductor 6 should be positioned on the leg 1B of the gap A. By doing
Since the magnetic flux in the air gap A is maintained at almost zero by the magnetic flux canceling effect of the superconductor 6, saturation can be prevented, and a sufficient amount of magnetic flux can be passed to further enhance the current limiting effect. is there. A superconductor 2 short-circuited as a secondary winding is wound inside the leg 1A on one side, and a primary winding 3 is wound around the outside thereof. Alternatively, the primary winding 3 may be wound inside and the short-circuited superconductor 2 may be wound outside.

[Fourth Embodiment] = FIG. 6 In this embodiment, as shown in FIG. 6, the position of the leg 1B having the gap A is located outside the iron core 1 and the leg 1B is A shorted general conductor winding or a shorted superconductor or a shorted superconductor winding 6 is located. The short-circuited superconductor 2 and the primary winding 3 are wound around the opposite leg 1A. The short-circuited superconductor 2 and the primary winding 3 are the primary winding 3 on the inside and the superconductor 2 on the outside in the drawing, but the reverse is also possible. Since the operation of the fourth embodiment is the same as that of the third embodiment, the same reference numerals are given to the same parts, and the description will be omitted.

[Fifth Embodiment] In this embodiment, the present invention is used as an inductor (INDUCTOR). That is, as shown in the first embodiment of FIG. 3, an open superconductor (winding) or an open general conductor winding 2 is provided inside one leg 1A of an iron core 1 having a gap A. Without winding the winding, a general conductor winding or a primary winding 3 which is a superconductor is installed on the outside so that the winding can be used as an inductor. This is the same as the first embodiment. However, the inductor is not limited to this. In the third and fourth embodiments (FIGS. 5 and 6), a short-circuited general conductor winding or a short-circuited superconductor is installed on the leg 1B having the air gap A. Including cases.

[Sixth Embodiment] In this embodiment, the present invention is used as a transformer. That is, the first as shown in FIG.
In the embodiment of the present invention, an open superconductor or an open general conductor winding 2 is used as a secondary load side on one side leg 1A of an iron core 1 having a gap A, and a general conductor winding or The primary winding 3, which is a superconductor, is installed and used as a transformer, and its operation is the same as that of the first embodiment. This embodiment is of course not limited to this, and as in the third and fourth embodiments (FIGS. 5 and 6), a general conductor winding short-circuited to the leg 1B having the air gap A or a superconductor short-circuited. Including when placing the body.

[0021]

According to the first aspect of the present invention described above, the short-circuited magnetic path and the magnetic path including the air gap are formed using the iron core 1 into which the air gap A capable of preventing the saturation is introduced. The primary winding and the superconductor are connected in parallel in the form of a magnetic circuit, and the path of magnetic flux at the time of an accident is changed from a magnetic path with no air gap to a magnetic path with an air gap. Can be restricted efficiently. Moreover,
Since the present invention can detect the fault current by itself and limit the fault current without the help of any external control device, it is possible to greatly reduce the complicated electronic circuit design and the resulting cost. It is possible to connect the power systems positively without replacing the existing power system, and it is possible to increase the capacity of the power system. Is obtained. In addition, the present invention is to prevent saturation by connecting a magnetic path including a gap and a general magnetic path in parallel so as to prevent saturation, and to prevent saturation in a magnetic path including a gap. Since a short-circuited superconductor or a short-circuited general conductor can be used, an excellent effect that the current limiting effect can be further increased by the magnetic flux canceling effect is obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a magnetic flux canceling effect of a superconductor.

FIG. 2 is a circuit diagram illustrating a power system to which the superconducting current limiting device of the present invention is applied.

FIG. 3 is a configuration diagram schematically showing a first embodiment of a superconducting current limiting device according to the present invention.

FIG. 4 is a configuration diagram schematically showing a second embodiment of the superconducting current limiting device of the present invention.

FIG. 5 is a configuration diagram schematically showing a third embodiment of the superconducting current limiting device of the present invention.

FIG. 6 is a configuration diagram schematically showing a fourth embodiment of the superconducting current limiting device of the present invention.

[Explanation of symbols]

A Air gap 1 Iron core 1A One side leg 1B Leg with air gap 1C Leg 2 Short-circuited superconductor or short-circuited general conductor (in case of superconducting current limiting device) Open superconductor or general conductor ( In the case of an inductor and a transformer) 3 Primary winding 4, 5 Closed magnetic circuit 6 Damping coil 10 Current limiting device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Zapea 123-10, Samseong-dong, Gangnam-gu, Seoul, Republic of Korea No. 903, Mok-dong, Mok-dong, Seoul, Korea

Claims (9)

[Claims] 1. A superconducting current limiting device having a core having a plurality of legs, wherein at least one of the legs has an air gap A capable of preventing saturation, the leg of the iron core has one leg. The secondary winding 3 and the short-circuited superconductor 2 are wound, and the gap A
A superconducting current limiting device having an air gap, wherein a closed magnetic path 4 containing no air gap and a closed magnetic path 5 containing the air gap A are connected in parallel to the primary winding 3 in a magnetic circuit manner. 2. The superconductor 2 short-circuited with the primary winding 3 is wound around different legs, and the primary winding 3 is wound around the same leg inside. The same as when the superconductor 2 is wound on the outside and the case where the superconductor 2 is wound on the same leg and the primary winding 3 is wound on the outside. The primary winding 3 and the superconductor 2
2. The superconducting current limiting device having an air gap according to claim 1, wherein the superconducting current limiting device is wound in a state of being alternately arranged. 3. An air gap A is formed outside the iron core 1, a primary winding 3 is provided inside one leg 1A, and a short-circuited superconductor 2 is provided outside. A superconducting current limiting device having a void introduced therein according to claim 1 or 2. 4. A short-circuited conductor or a short-circuited superconductor 6 is positioned on a parallel magnetic path other than the magnetic path formed by the primary winding 3. A superconducting current limiting device into which the void according to claim 3 is introduced. 5. The air gap A is formed outside the iron core 1, and a short-circuited conductor or a short-circuited superconductor 6 is positioned in a parallel magnetic path other than the magnetic path formed by the primary winding 3. The superconducting current-limiting device according to claim 1, wherein the device is provided with a void. 6. A combination of a plurality of air gaps A and a plurality of damping coils in order to combine a plurality of magnetic circuits connected in parallel. A superconducting current-limiting device into which the gap A according to claim 3, 4, or 5 is introduced. 7. An open superconductor or an open general conductor winding 2 or no inside of one side leg 1A of an iron core 1 having an air gap A, and a general conductor winding or an outside outside thereof. A superconducting primary winding 3 is installed, and a general conductor winding short-circuited to a parallel magnetic path other than the magnetic path formed by the primary winding 3 or a short-circuited superconductor 6 is installed as an inductor. 7. The superconducting current limiting device having a void introduced therein according to claim 2, wherein the device is used. 8. A superconductor or an open general conductor winding 2 which is opened as a secondary side inside the one side leg 1A of the iron core 1 having the air gap A, and a general conductor winding or the outside is opened outside. The primary winding 3 which has become a superconductor is installed, and a short-circuited general conductor winding or a short-circuited superconductor 6 is installed in a parallel magnetic path other than the magnetic path in which the primary winding 3 can be installed. 2. The method according to claim 2, wherein the transformer is used as a transformer.
Or a superconducting current limiting device into which the void according to claim 6 is introduced. 9. The superconductor 2 is one of a linear body and a plate-like body, according to claim 1, 2, 3, 4, 5, or 6. A superconducting current-limiting device into which the void according to claim 7 or 8 is introduced.