JPH01206831A - Superconducting phase breaking device for superconducting wire - Google Patents

Abstract

PURPOSE:To interrupt the currents of a wire quickly by arranging the superconducting wire to a gap for an annular core, to which a winding is applied. CONSTITUTION:Large currents are made to flow through a primary circuit by mutual inductance L1 at the same time as the closing operation of a switch S, and a winding L is excited and a strong AC magnetic field is generated in a gap 21 for a ring core 20. Consequently, when a magnetic field higher than the critical field of a superconducting wire G is applied to the superconducting wire G, superconductive phase is broken, and the magnetic field transfers from a superconductor to a non-superconductor in a short time and normal currents L made to flow through a main wire 10 are interrupted. On the other hand, large currents made to flow through the winding L are interrupted while the winding L is demagnetized and the magnetic field generated in the gap 21 for the ring core 20 disappears by opening the switch S for a breaking device DV in order to return the state to the state of feed at the time of normalcy. Accordingly, the superconducting wire G transfers from the non-superconductor state to the superconductor state in a short time.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a method for arbitrarily insulating a superconducting wire from a superconductor by destroying the superconducting phase of a superconducting wire connected to a power system line and having a current-limiting effect. The present invention relates to a superconducting phase breakdown device for a superconducting wire, which interrupts or allows current flowing through the line by transferring it from a body or an insulator to a superconductor.

[Conventional technology]

In general, an electric power system is a system that integrates everything from generation to consumption of electric power, that is, it generates electricity at a power plant, transmits it through transmission lines, and then distributes it to factories and homes using distribution lines, and then distributes it to the load equipment. It refers to the system that includes everything up to. Electric power transported by transmission lines cannot be suddenly supplied to consumers at the same transmission voltage, so the voltage must be stepped down several times to a voltage that is suitable for the demand load.

In a grid-connected power system, if an accident occurs somewhere along the lines, the effects will immediately spread to the entire region. Therefore, even if an accident occurs, it is extremely important to suppress its effects locally and prevent it from spreading to other areas, from the standpoint of maintenance and safety, as well as from the standpoint of ensuring a constant supply of power.

There are many types of accidents that occur on power transmission lines, but they include abnormal voltage generation due to lightning strikes, and excessive current flowing due to line short circuits and ground faults. For this reason, to protect against abnormal voltages, overhead ground wires or buried ground wires are installed on power transmission lines to protect the lines, and various types of lightning arresters are installed near the entrances or exits of the lines at power plants and substations. , when abnormal voltage waves attack, they are temporarily grounded and guided to the earth in an effort to prevent insulation breakdown in electrical facilities. In addition, if a power line is short-circuited or grounded due to disconnection or contact, a strong current will flow to the fault location and burn out the electrical equipment in the circuit, so as a measure to prepare for such an unexpected situation, certain sections of the line A current limiting line may be provided for each area. This is to prevent the effects of an accident from spreading by cutting off the faulty section and cutting off the current by the current-limiting action of the current-limiting wire at the same time that a large current flows through the line.

Such current-limiting wires are usually constructed as electric wires by covering a conductor with a current-limiting function with an insulating coating,
A superconducting wire made of a metallic superconducting material, or a superconducting f! made of a ceramic superconducting material previously proposed by the present inventor. (See Japanese Patent Application No. 62-248935).

Of these, apart from electric wires that are normal conductors, superconducting wires made of metal or ceramic superconducting materials have no electrical resistance at all due to their superconducting state and allow current to flow without loss during normal times, but due to large currents in the event of an accident, It is characterized by immediately transitioning from a superconductor to an insulator to perform a current limiting action. In other words, the critical current of the superconducting wire is preset according to the allowable current of the line (for example, in the case of the main line of a distribution system line, the voltage is 600 V and the allowable current is 20,000 A, so the critical current is 20,000 A).
When the fault current reaches this level, the superconducting phase of the superconducting wire breaks down, instantly transitioning from a superconductor to an insulator, cutting off the large current.

[Problem B to be solved by the invention] By the way, in an electric power system, it is necessary to periodically inspect the network of lines for maintenance and management purposes. In such cases, in addition to automatically cutting off excessive current due to an accident using a current limiting line, during inspections or restoration work, the current flowing through the line is actively cut off in certain sections regardless of the accident. Therefore, efforts must be made to protect operators of electrical facilities from electricity. For this purpose, it is preferable to install a device for arbitrarily transferring the superconducting wire used as a current limiting wire from an electrically sensitive conductor to an insulator or from an insulator to a superconductor together with the superconducting wire.

Furthermore, as the demand load increases with the development of industry, the power system will gradually expand in scale and become more complex due to the development of power sources and the reinforcement of facilities. Electricity companies provide an abundance of high-quality electricity,
In order to be able to supply electricity at low levels, this entire power system must always be operated rationally and economically, and it is essential to minimize the total cost of electricity supplied to the loads.

Therefore, in view of the above points, it is an object of the present invention to transition a superconducting wire, which serves as a current limiting line connected to a power system line, from a superconductor to an insulator or from an insulator to a superconductor, regardless of the large current caused by an accident. The goal is to provide the means to do so.

[Means for Solving the Problem] The object is to provide a device for destroying the superconducting material of a superconducting wire having a current-limiting action connected to a line of a power system, the device comprising: an annular iron core provided with a winding; It is composed of a circuit that forms a gap in the annular core and includes an AC power supply that flows an alternating current to the winding, a switch that cuts off or turns on the alternating current, and an inductance that changes the alternating current. This is achieved by a superconducting phase breaking device for a superconducting wire, which is characterized in that a superconducting wire is arranged in a superconducting wire.

The superconducting phase breaking device of the present invention actively brings out the current limiting effect of a superconducting wire made of a metallic or ceramic superconducting material. That is, as is well known, the requirements for maintaining a superconducting state are a critical temperature, a critical current, and a critical magnetic field, and unless all three conditions are satisfied, the superconductor will not become a superconductor. However, the destruction device of the present invention uses a circuit using an inductance. This is used to exceed the critical magnetic field among the three conditions, to cause the superconducting wire to transition from a superconductor to an insulator, and to actively exhibit a current limiting effect. Therefore, in order to cut off an arbitrary section during line inspection or restoration work, a destructive device is operated to apply a magnetic field greater than the critical magnetic field of the superconducting wire to the superconducting wire, destroying the superconducting phase of the superconducting wire. By transferring from the superconductor to the insulator, the current in the section can be interrupted.

〔Example〕

Hereinafter, the superconducting phase breaking device for a superconducting wire of the present invention will be specifically described based on examples.

FIG. 1 shows a schematic circuit in the case where a superconducting phase breakdown device DV of one embodiment is attached to a zero line 10 of a line of a power system. As mentioned above, the superconducting wires G made of metallic or ceramic superconducting materials with current-limiting action are installed at certain sections of the main line 10, and are designed to prevent excessive current exceeding the allowable value from occurring due to accidents such as short circuits and ground faults. When the current flows to vA10, it instantly changes from a superconductor to an insulator to cut off the large current. Normally, a mechanism for reliably disconnecting the main line 10 is provided in addition to the superconducting wire G to protect the operator of the electrical facility from electric shock. As is clear from the figure, this mechanism includes, for example, a shunt resistor r connected to the zero wire 10,
Coil 11 connected in series to shunt resistor r, coil 11
The iron rod 12 is inserted into the interior and is displaced as the iron rod is energized and demagnetized.
, a coil spring 13 attached to the end of the iron rod 12, and a switch 1 that opens and closes the main line IO according to the displacement of the iron rod 12.
4.

However, it is preferable that the disconnection mechanism of the main line 10 attached to the main line 10 is provided with an additional mechanism for fixing the switch 14 in an open state as necessary. According to this mechanism, when the superconducting mc is a superconductor and normal current ■ is flowing in the main line 1°, the current shunted from the main line 10 by the shunt resistor r flows through the coil 11.
1 is excited, the iron rod 12 overcomes the biasing force of the coil spring 13 and is displaced in the direction of the arrow, and the switch 14 is in a closed state. Since the current in the main line 10 is cut off at the same time as the current limiting action of the superconducting wire G, no current flows through the shunt resistor r (as a result, the coil 11 is demagnetized and the iron bar 12 is
is displaced in the direction of arrow A due to the restoring force of switch 14.
opens and disconnects the main line 10. By disconnecting the main line 10, reverse flow of current in the main line 10 can also be prevented. Since the superconducting wire G becomes an insulator after the current limiting action, the possibility of current backflow is extremely small, but this is a measure to be taken in case of an emergency. The superconducting wire G, whether metal-based or ceramic-based, differs depending on the critical temperature of the superconducting material, but in order to maintain its superconducting state, it is housed in a cooling tank 15 containing a coolant and constantly cooled. has been done.

As shown in Fig. 2, the superconducting phase breakdown bag ffDV consists of a ring-shaped core 20 partially wound with windings, an AC power source AC that flows an alternating current through the windings , and an AC power source AC that cuts off or turns on the alternating current. The circuit includes a switch S for changing the alternating current, and an iron core human phase pressure inductance L1 for changing the alternating current. Furthermore, a resistor R for limiting the current flowing to the primary circuit is connected to the circuit on the secondary coil side, and a resistor ``for load'' is connected to the circuit on the secondary coil side. Gaps 21 are formed at regular intervals, and the superconducting wire G is placed in this gap 21. As is clear from the figure, the wound annular core 20 is housed in the cooling tank 15 together with the superconducting wire G. Although not particularly shown in the diagram, the switch S is installed with the operating part away from the destruction bag WDV to avoid direct manual operation, which is dangerous for large-capacity, high-voltage systems such as power system power lines. However, it is appropriate to enable mechanical or electrical control from a distance.

The destructive device D■ having such a structure operates the switch S to cause a large current to flow through the primary circuit through the mutual inductance L1,
This large current is passed through the winding, and the gap 2 of the annular core 20 is
By generating a strong alternating magnetic field greater than the critical magnetic field of the superconducting wire G in the gap 21, the magnetic field is applied to the superconducting wire G disposed in the gap 21, thereby destroying the superconducting phase of the superconducting wire G.

Regarding the operation of the power system equipped with this superconducting phase breaker DV, when power is normally supplied from the zero wire 10, the switch S of the breaker DV is kept open to demagnetize the windings.

Next, in order to protect workers from electric shock during inspection work for maintenance and management or recovery work after an accident, a destructive device is required to cut off the current flowing through the main line in the section where work is being carried out and isolate the section. It is sufficient to close the switch S which is in the open state of DV. Simultaneously with the closing operation of the switch S, a large current flows through the primary circuit due to the mutual inductance Ll, the winding is excited, a strong alternating current magnetic field is generated in the gap 21 of the annular iron core 20, and a magnetic field greater than the critical magnetic field of the superconducting wire G is generated. is applied to the superconducting wire G, the superconducting phase of the superconducting wire G is destroyed,
The superconductor instantly transitions to an insulator and interrupts the normal current flowing through the main line 10. When the current is cut off, the switch 14 opens as described above, disconnecting the zero wire 10 and completely disconnecting the section, allowing workers to work with peace of mind without the risk of electric shock. It is possible.

- As is well known, a large current several times the AC current flows in the secondary circuit. - Due to the AC voltage applied to the primary coil, an exciting current flows through the primary coil at a angle of 90 degrees from the phase of the voltage, generating a magnetic field. However, an induced electromotive force is generated in the secondary coil, and an induced current flows through the secondary circuit due to the load resistor r. Along with this, a new current having a phase opposite to the induced current flows through the secondary coil so as to cancel the magnetic field due to the induced current of the secondary coil. As a result, a current larger than the alternating current flows through the negative circuit.

On the other hand, in order to restore the normal power supply state, the destructive device D
By opening the switch S of V, the large current flowing through the winding is cut off, and at the same time, the winding is demagnetized and the magnetic field generated in the gap 21 of the annular iron core 20 disappears. As a result, the superconducting wire G instantaneously changes from an insulator to a superconductor, and in parallel with this, if the switch 14 of the disconnection mechanism of the wooden wire 10 is closed, power supply from the main wire 10 is resumed.

Note that the zero wire 10 is disconnected by the disconnection mechanism when the superconducting wire G transitions from a superconductor to an insulator.
Although it is not particularly necessary to keep the switch S closed, it is preferable not to open the switch S in order to ensure multiple safety.

The present invention is not limited to the above embodiments, and various embodiments may be adopted as long as the purpose of the present invention is achieved.
For example, although mutual inductance is used in the circuit of the above embodiment, self-inductance may of course be used. However, in the case of mutual inductance, the current flowing through the primary circuit can be easily adjusted by appropriately setting the load on the secondary circuit.

〔Effect of the invention〕

As explained above, the superconducting phase breaking device for a superconducting wire of the present invention uses a circuit using an inductance to change an alternating current to forcibly apply a magnetic field higher than the critical magnetic field to the superconducting wire, thereby making the superconducting wire conductive. Since it destroys the phase,
The superconducting wire can be instantly transferred from a superconductor to an insulator whenever necessary for inspection or restoration work, and the current on the line can be quickly and effectively interrupted, which is extremely convenient for line maintenance and management. This makes it possible to operate the power system rationally and economically.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the superconducting phase breaking device for superconducting wires of the present invention, and is a schematic circuit diagram showing an example of how the line is attached to the main line in a power system, and Fig. 2 shows the annular core of the breaking device of Fig. 1. FIG. 3 is a schematic front view of the superconducting wire as seen from the upstream side. D: Superconducting phase breaking device 10: Main wire 20: Annular core 21: Gap: Winding AC: AC power source S: Switch R, r: Resistor Ll: Mutual inductance G: Superconducting wire patentee Mitsubishi Cable Industries, Ltd. Company□゛τ

Claims (1)

[Claims] This is a device for destroying the superconducting phase of a superconducting wire that has a current-limiting effect connected to a power system line, and includes a ring-shaped core with windings, a gap formed between the ring-shaped core, and an alternating current applied to the winding. A superconducting wire comprising a circuit equipped with an AC power supply that flows an AC current, a switch that cuts off or turns on the AC current, and an inductance that changes the AC current, and characterized in that the superconducting wire is arranged in the gap of an annular core. superconducting phase destruction device.