JPH01177827A - Superconducting phase destroying device for superconducting wire - Google Patents

Abstract

PURPOSE:To shift a superconducting wire from a superconductor to a nonsuperconductor in a short time by employing a circuit for utilizing the charge/discharge of a capacitor, and forcibly applying a magnetic field of its critical magnetic field or more to the wire, thereby destroying its superconducting phase. CONSTITUTION:Before a discharge, a capacitor C is charged. When a switch S2 is closed, a large current flows to a circuit by the discharge of the capacitor C, a winding L is energized to generate a strong magnetic field in the gap of an annular core 20. When a magnetic field of the critical magnetic field or more of a superconducting wire G is applied to the wire G, the superconducting phase of the wire G is destroyed, the lead is shifted from a superconductor to a nonsuperconductor in a short time, thereby breaking a normal current I flowing to the main line 10.

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 to a voltage that is convenient 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, lines are protected by installing overhead ground wires or buried ground wires at the transmission tNIA, and various types of lightning arresters are installed near the line entrances or exits 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 the 1itvA line is short-circuited or grounded due to disconnection or contact, a huge current will flow to the fault location and burn out the electrical equipment in the circuit. In some cases, @streamlines are provided for each fixed section. this is,
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,
There are superconducting wires made of metallic superconducting materials, and superconducting wires made of ceramic superconducting materials 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 set in advance 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 a level higher than 100%, the superconducting phase of the superconducting wire breaks down and instantly changes from a super iIt conductor to an insulator, interrupting the large current.

[Problem to be solved by the invention]

By the way, in the power system, the network of lines needs to be periodically inspected 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. We must strive to protect operators of electrical facilities from IL*.This includes devices that can optionally transfer superconducting wires used as current-limiting wires from superconductor to insulator or from insulator to superconductor. It is preferable to install the superconducting wire 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 to a fine amount of electricity, 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 convert a superconducting wire as a current limiting line connected to a power system line into a superconductor from an insulator or from an insulator to a superconductor, regardless of the large current caused by an accident. The purpose is to provide the means to make the transition.

[Means for Solving the Problem] The object is to provide a device for destroying the superconducting phase of a superconducting wire having a current-limiting action connected to a line of a power system, which comprises: a ring-shaped iron core provided with a winding; A gap is formed in the annular iron core, and it is equipped with a DC power supply for obtaining DC current, a capacitor for charging and discharging DC current, and a switch for charging and discharging the capacitor. This is achieved by a superconducting phase breakdown device for superconducting wires, which is composed of a circuit that charges a direct current and then discharges a capacitor to send a discharge current to the windings, and is characterized in that the superconducting wires are arranged in the gears of a ring-shaped iron core. .

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. In other words, as is well known, the requirements for maintaining a superconducting state are a critical temperature, a critical current, and a critical magnetic field, and if all three conditions are not satisfied, the superconductor will not become a superconductor. 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 disconnect any section during line inspection or restoration work, ``operate the destruction device to apply a magnetic field greater than the critical magnetic field of the superconducting wire to the superconducting wire, destroy the superconducting phase of the superconducting wire, and By transitioning the wire from a superconductor to an insulator, the current in that 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 diagram when a superconducting phase breakdown bag WDv according to an embodiment is attached to the main line 10 of a power system line. The line G is installed at certain sections of the main line 10, and if an accident such as a short circuit or ground fault occurs, an excessive current exceeding the allowable value may be generated. When the current flows to 110, it instantaneously changes from a superconductor to an insulator, cutting off the large current. Normally, a mechanism for reliably disconnecting the main line 10 is provided in addition to the superconducting wire G as a measure to protect the operator of the electrical facility from damage. As is clear from the figure, this mechanism includes, for example, a shunt resistor r connected to the main vA10, a coil 11 connected in series to the shunt resistor r, and a coil 11 that is inserted into the coil 11 and is displaced as it is energized and demagnetized. Iron rod 12, coil spring 13 attached to the end of iron rod 12
, and a switch 14 that opens and closes the main line 10 according to the displacement of the iron rod 12.

However, it is preferable that the disconnection mechanism for the main line 10 attached to the zero 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 wire G is a superconductor and a normal current I is flowing through the main wire 10, the current shunted from the zero wire 10 by the shunt resistor r flows through the coil 11, and the coil 1
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, the coil 11 is demagnetized, and the iron bar 12 is connected to the coil spring 13.
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 destruction device DV includes a ring-shaped core 20 partially winding, a DC power supply DC for obtaining direct current, and a DC power supply for charging and discharging the direct current. A capacitor C, a switch S1 that charges the capacitor C with direct current, and a switch Sz that discharges the capacitor C.
It is composed of a circuit comprising: Further connected to this circuit are a resistor Rc for suppressing the direct current of the DC power supply DC and a resistor RL for suppressing the discharge current of the capacitor C. Gear knobs 21 are formed at regular intervals on the annular core 20, and the superconducting wire G is placed in the gap 21. As is clear from the figure, the wound annular core 20 is housed in the cooling tank 15 together with the superconducting vAG. has been done. Although not shown in the diagram, the switches Sr and St should be installed away from the destructive device DV to avoid direct manual operation, which is dangerous for large-capacity, high-voltage systems such as the main line of the power system. , it is appropriate to enable mechanical or electrical control from a distance.

The breaking device DV having such a structure operates the switches S+ and St, causes the discharge current of the capacitor C to flow through the circuit, causes a large discharge current to flow through the winding, and causes the gap 21 of the annular iron core 20 to exceed the critical magnetic field of the superconducting wire G. By generating a strong magnetic field, the magnetic field is applied to the superconducting wire G disposed in the gap 21, and the superconducting phase of the superconducting wire G is destroyed.

Regarding the operation of the power system equipped with this superconducting phase destruction device DV, during normal operation when power is supplied from the zero wire 10, the destruction bag f
At least switch S2 of both switches of the iDV is opened to demagnetize the winding.

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. Switch St, which is in the open state of DV, is closed to discharge capacitor C. Naturally, it is necessary to charge the capacitor C before discharging it. This includes:
When the switch S2 is open, the switch S is closed, and the DC'r! of the DC power supply DC is turned off. A large current flows through the circuit due to the discharge of the capacitor C at the same time as the closing operation of the switch S8, and the winding is excited and the annular iron core 2
When a strong magnetic field is generated in the gap 21 of 0 and a magnetic field higher than the critical magnetic field of the superconducting wire G is applied to the superconducting wire G, the superconducting phase of the superconducting wire G is destroyed and the superconducting wire G instantly transitions from a superconductor to an insulator. The normal current flowing through the zero wire 10 is cut off. When the current is cut off, switch 1 is activated as described above.
4 opens and disconnects the main line 10, completely separating the section, so workers can carry out their work with peace of mind without the risk of electric shock.

After the capacitor C has finished discharging, no current flows in the circuit, the magnetic field generated in the gap 21 of the annular iron core 20 disappears, and the superconducting wire G transitions from an insulator to a superconductor, but the switch 14 switches to the zero wire. 10 is disconnected, so no current flows in that section.

On the other hand, to return to the normal power supply state, switch 1
4, power supply from the zero wire 10 is restarted. At this time, the switch S2 of the destruction device DV is returned to the open state, and if necessary, the switch SI is closed to charge the capacitor C again.

The present invention is not limited to the above embodiments, and various types of M may be adopted as long as the purpose of the present invention is achieved.

For example, in the circuit of the above embodiment, since the magnitude of the magnetic field generated in the gap of the annular core is proportional to the magnitude of the discharge current of the capacitor, it is preferable to use a capacitor with a larger capacitance. In addition to the circuit using one capacitor, a circuit using a plurality of capacitors may be used.

〔Effect of the invention〕

As explained above, the superconducting phase breaking device for superconducting wire of the present invention employs a circuit that utilizes capacitor charging and discharging, thereby forcibly applying a magnetic field greater than the critical magnetic field to the superconducting wire to destroy the superconducting phase. Therefore, whenever necessary for inspection or restoration work, the superconducting wire can be instantly transferred from superconductor to insulator, and the current in the line can be cut off quickly and effectively, 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 L Two windings DC: DC power source Sl/S2: Switch RC, RL Two resistors C: Capacitor G: Superconducting wire patent applicant Mitsubishi Cable Industries, Ltd. Company procedure amendment cap button

Claims (1)

[Claims] A device for destroying the superconducting phase of a superconducting wire with a current-limiting effect connected to a power system line, which forms a gap between a wound annular core and the annular core to obtain direct current. The device is equipped with a DC power supply, a capacitor for charging and discharging DC current, and a switch for charging and discharging the capacitor.The capacitor is charged with DC current by opening and closing the switch, and then the capacitor is discharged to wind the capacitor. A superconducting phase breaking device for a superconducting wire, which is composed of a circuit that causes a discharge current to flow through the wire, and is characterized in that the superconducting wire is arranged in the gap of an annular iron core.