JPH10228849A - D.c. breaker device, and d.c. power transmission system using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a D.C. breakout device without needing a cooling means to obtain a D.C. power transmission system using, by providing a bypass switch in parallel to a semiconductor switch element, connected to a D.C. line in series and in a normal direction, and releasing a bypass switch at the time of breaking a current, also adding reverse voltage to the main electrode of the semiconductor switch element to break the current. SOLUTION: A reverse blocking three-terminal thyristor 11 is not heated by a bypass line 14 at a normal time, and at a breaking time at first, an ON signal is given to the gate of the thyristor 11 to conduct the thyristor element to open the switch S of the bypass line 14. The movable piece of a change-over switch 34 is fixed to the thyristor element side to be broken, and a driving switch 33 is turned on to a cathode line 2 side to store energy in a capacitor 31. Then when the driving switch 33 is depressed to the change-over switch 34 side, the energy, stored in the capacitor 31, is applied as reverse voltage to make the thyristor 11 into a cutoff condition cutoff the D.C. current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC cut-off device having a function of supplying a DC current of a power system and a function of cutting off the DC current of the power system in the event of an abnormality such as a ground fault or short circuit, and a DC cut-off device. The present invention relates to a DC power transmission system in which is used.

[0002]

2. Description of the Related Art FIG. 12 is a publication of the 1995 IEEJ National Convention, p. 6-341, 342, 355, 356, and the 11th International Conference on Gas Discharge and Its International Conference, pp. 378-pp.
381 "is a view schematically showing the DC power transmission system shown in FIG.

In FIG. 12, 1 is a positive main line for transmitting a positive potential direct current, 2 is a negative main line for transmitting a negative potential direct current,
Reference numerals 3 and 4 denote a neutral line (return line) which is a return line of direct current, 5 denotes a plurality of rectifiers (thyristor valves), and 6 denotes a neutral line protection shutoff provided between two neutral lines 3 and 4. And 7, a return circuit breaker provided on the neutral conductors 3 and 4, respectively.

The circuit breaker 6 for protecting a neutral conductor is usually composed of a puffer type SF ₆ gas circuit breaker 61, a reactor 63 connected in series to a capacitor 62, and a surge absorber 64 connected in parallel. Also, return circuit protection circuit breaker 7
Is usually configured by connecting a puffer type SF ₆ gas circuit breaker 71, a reactor 73 connected in series to a capacitor 72, and a surge absorber 74 in parallel.

Next, the operation of the DC power transmission system will be described. First, a case where power is transmitted using only the positive electrode side of the DC power transmission system will be described. In the conversion transformer 91 and the rectifier (thyristor valve) 5 installed on the side where the electric energy is sent, the AC electric energy is boosted to plus several hundred kilovolts and rectified to a direct current of about several thousand amps. Power is transmitted by the main line 1.

On the other hand, in the rectifier (thyristor valve) 5 and the conversion transformer 93 installed on the side receiving the rectified electric energy, after this electric energy is converted into AC power, the DC current transmitted is , And returns to the side that sends the electric energy through the neutral wire 3 and is grounded (earthed).

[0007] Similarly, a case in which power is transmitted using only the negative electrode side of the DC power transmission system will be described. In the conversion transformer 92 and the rectifier (thyristor valve) 5 installed on the side where the electric energy is sent, after the AC electric energy is boosted to minus several hundred kilovolts and rectified to a DC current of several thousand amperes, Power is transmitted by the negative electrode main line 2.

On the other hand, in the conversion transformer 94 and the rectifier (thyristor valve) 5 installed on the side receiving the rectified electric energy, after this electric energy is converted into AC power, the DC current transmitted is It returns to the side that sends the electric energy via the neutral wire 4 and is grounded (earthed).

In the normal operation state using only one pole of the DC power transmission system, the return circuit protection circuit breaker 7 provided on the neutral conductors 3 and 4 is open (OFF).
When a short circuit accident occurs in the neutral wires 3 and 4, the return circuit protection circuit breaker 7 is closed (ON), and the neutral wires 3 and 4 are grounded (earthed).

After the insulation of the neutral wires 3 and 4 has been secured (the cause of the accident has been eliminated), the return circuit protection circuit breaker 7 is opened again (OFF) to return to normal operation using only one pole. I do.

Next, a case in which power is transmitted using both the positive electrode and the negative electrode of the DC power transmission system will be described. In the conversion transformer 91 and the rectifier (thyristor valve) 5 installed on the side where the electric energy is sent, this electric energy is boosted to plus several hundred kilovolts and rectified to a direct current of about several thousand amps, and then converted to a positive electrode. Power is transmitted by the main line 1.

On the other hand, a rectifier (thyristor valve) 5 and a conversion transformer 9 installed on the side receiving electric energy
After the electric energy is converted into an alternating current at 3,94, the direct current is boosted to minus several hundred kilovolts at a converter 92 and a rectifier (thyristor valve) 5 installed on the side receiving the electric energy. Then, it returns to the side that sends electric energy through the negative electrode main line 2. In this case, the current flowing through the two neutral wires 3 and 4 is zero.

In a normal operation state using both poles of such a DC transmission system, the neutral protective circuit breaker 6 provided between the two neutral conductors 3 and 4 is closed (ON). I have. The return circuit protection circuit breakers 7 provided on the neutral wires 3 and 4 are open (OFF). When an accident or the like occurs on the positive electrode side or the negative electrode side and it is necessary to switch to the unipolar operation, the neutral protective circuit breaker 6 is opened (OFF), and the positive electrode side and the negative electrode side are separated from each other. .

Next, the operation and principle of blocking the DC current in the neutral line protection circuit breaker 6 and return line protection circuit breaker 7 will be described. The DC current interruption process includes a neutral line protection circuit breaker 6 and a return line protection circuit breaker 7 respectively.
Is started by opening the contacts of the puffer type SF ₆ gas circuit breakers 61 and 71 constituting the above. When the contacts are opened, a DC arc is generated. At this time, the gas pressure in the puffer chambers of the puffer type SF ₆ gas circuit breakers 61 and 71 increases, and SF ₆ gas is blown to the arc generated between the contacts. .

Puffer type SF ₆ gas circuit breakers 61 and 71
Resistance characteristics of puffer type SF ₆ gas circuit breakers 61 and 7
Due to the interaction of the capacitors 62 and 72 and the reactors 63 and 73 connected in parallel with each other, when these circuit conditions are in an unstable condition, the small disturbance generated in the DC arc current is gradually enlarged, When the amplitude of the current oscillation increases and finally reaches the current zero point, the arc is extinguished,
Voltage recovers.

Also, surge absorbers 64 and 7 connected in parallel to the puffer type SF ₆ gas circuit breakers 61 and 71
4 suppresses an overvoltage of the transient recovery voltage after the interruption.

[0017]

THE INVENTION Problems to be Solved by the DC blocking device in such a DC transmission system, puffer type SF ₆ gas circuit breaker is used as a protective circuit breaker. However, inhibition in view of global environmental conservation, cooler, so as to suppress consider freon and halogen gas are used in electrical equipment such as a refrigerator has been promoted, SF ₆ gas in terms of preservation of the global environment Be considered for consideration.

Therefore, a circuit breaker not using SF ₆ gas,
It is necessary to propose a DC power transmission system using such a circuit breaker. As a circuit breaker that does not use SF ₆ gas to block alternating current, it functions as a reverse blocking three-terminal thyristor (thyristor element), which is a type of semiconductor switching element, and a triac in which a reverse blocking three-terminal thyristor is connected in reverse parallel. What they have is being considered as a circuit breaker.

The triac gives a signal to the gate of a reverse blocking three-terminal thyristor element having different conduction directions (ON
Then, each reverse blocking three-terminal thyristor element becomes conductive (ON), and an alternating current flows between the triacs. Since the alternating current crosses the current zero point every half cycle, when the gate signal is cut off (turned off), the thyristor element is cut off (OFF) at the current zero point, and the alternating current is cut off.

However, different from the case where the DC current is cut off by the circuit breaker using the thyristor element and the case where the AC current is cut off, the DC current does not periodically cross the current zero point. Operation cannot interrupt DC current. In addition, when a current having a large energy is supplied to the thyristor element for a long time, a cooling means is required, and further, when a surge occurs, the expensive thyristor element is destroyed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is a compact thyristor which can cut off bidirectional DC current and does not require cooling means as a circuit breaker not using SF ₆ gas. It is an object of the present invention to provide a DC cutoff device using an element and a DC power transmission system using the thyristor-type DC cutoff device.

[0022]

According to a first aspect of the present invention, there is provided a DC cutoff device, comprising: a semiconductor switching element serially connected to a DC line in a forward direction; current bypass means provided in parallel with the semiconductor switching element; Current interrupting means for applying a reverse voltage to the main electrode of the semiconductor switching element when the current flowing through the semiconductor switching element is interrupted, and opening the current bypass means when interrupting the DC current flowing through the DC line; The element is turned off by applying a reverse voltage to the main electrode of the element.

According to a second aspect of the present invention, there is provided a DC cutoff device comprising a semiconductor switching element connected in parallel in a reverse direction to a semiconductor switching element connected in series in a forward direction to a DC line. Current interrupting means for applying a reverse voltage to the electrodes.

According to a third aspect of the present invention, the DC switching device comprises a semiconductor switching element formed by a three-terminal reverse blocking thyristor, and a reverse voltage is applied to the main electrode by a current blocking means.

According to a fourth aspect of the present invention, there is provided a DC cutoff device wherein each of the semiconductor switching elements connected in antiparallel is constituted by a reverse blocking three-terminal thyristor, and a reverse voltage is applied to a main electrode of the thyristor by a current cutoff means. .

According to a fifth aspect of the present invention, there is provided a DC cutoff device wherein the semiconductor switching element is constituted by a gate turn-off thyristor, and a reverse voltage is applied between the gate and the cathode by current cutoff means.

According to a sixth aspect of the present invention, in the DC cutoff device, the current cutoff means includes a capacitor charged with a DC voltage applied to the DC line, and a charge / discharge terminal of the capacitor connected to the mains of the semiconductor switching element from the DC line. A switching switch for switching to an electrode, wherein when a DC current is interrupted, a charging voltage of the capacitor is discharged to the main electrode to apply a reverse voltage.

According to a seventh aspect of the present invention, in the DC cutoff device, the current cutoff means switches a capacitor charged with a DC voltage applied to the DC line and a charge / discharge terminal of the capacitor from the DC line to a semiconductor switching side. First
And a second changeover switch for changing the output of the first changeover switch to the main electrode of each of the semiconductor switching elements connected in anti-parallel. Accordingly, the main electrode to which the capacitor is discharged with the charging voltage is switched by the second switch to discharge, and a reverse voltage is applied.

According to a twelfth aspect of the present invention, there is provided a DC cutoff device, wherein the current cutoff means includes a capacitor charged by a DC voltage applied to a DC line, and a charge / discharge terminal of the capacitor connected to the gate of a gate turn-off thyristor by the DC power supply. And a charge switch for discharging a charge voltage of the capacitor to the gate and applying a bias voltage between the gate and the cathode when the DC current is cut off.

According to a ninth aspect of the present invention, there is provided a DC cutoff device, wherein the current cutoff means includes a capacitor charged by a DC power supply and a changeover switch for switching a charge / discharge terminal of the capacitor from the DC line to a main electrode of a semiconductor switching element. And discharging a charging voltage of the capacitor to the main electrode and applying a reverse voltage when a DC current is interrupted.

According to a tenth aspect of the present invention, there is provided a
Current interrupting means for connecting a capacitor charged by a DC power supply, a first switch for switching a charge / discharge terminal of the capacitor from the DC line to a semiconductor switching side, and an anti-parallel connection of an output of the first switch; A second changeover switch for changing over to a main electrode of each of the semiconductor switching elements, wherein when the DC current is interrupted, the main electrode to which the charging voltage of the capacitor is discharged is switched in accordance with the direction of the DC current. It is switched by a switch to discharge and apply a reverse voltage.

According to the eleventh aspect of the present invention,
The current cutoff means includes a capacitor charged by the DC power supply, and a changeover switch for switching a charging / discharging terminal of the capacitor from the DC power supply to a gate of a gate turn-off thyristor, and the charging voltage of the capacitor is cut off when the DC current is cut off. And a reverse voltage is applied between the gate and the cathode.

According to a twelfth aspect of the present invention,
One end of the reactor is connected to the capacitor, and the other end is grounded.

According to a thirteenth aspect of the present invention, there is provided a
A transient overvoltage suppression element connected in parallel to a semiconductor switching element is connected in parallel.

According to a fourteenth aspect of the present invention, there is provided a DC power transmission system using a DC power cutoff device, which is disposed on a first power transmission side and converts AC power for power transmission into DC power. A positive main line for transmitting only the positive side of the converted DC power to the power receiving side, a first inverter for converting the transmitted positive side DC power to AC power, and after being converted to AC power A first neutral wire that returns the DC current to the power transmission side and is grounded, and is disposed on the second power transmission side;
A second converter for converting the AC power for transmission to DC power, a negative main line for transmitting only the negative side of the converted DC power to the power receiving side, and an AC power source for transmitting the transmitted DC power on the negative side. A second inverter for converting the power to electric power, a second neutral line that is converted to AC power and returns a DC current to the power transmission side and grounded, and the first and second neutral lines. And a first and second return line protection circuit breaker provided between each neutral line and the ground, the first and second return lines being provided between the neutral line and ground. At least one of the line protection circuit breaker and the neutral line protection circuit breaker uses a DC switching circuit using a semiconductor switching element according to claim 1.

According to a twelfth aspect of the present invention, there is provided a direct current transmission system using a direct current cutoff device, wherein a semiconductor switching element is constituted by a three-terminal reverse blocking thyristor, and a main electrode is supplied with a reverse voltage by a current interrupting means. It is designed to be cut off.

According to a twelfth aspect of the present invention, there is provided a direct current power transmission system using the direct current cutoff device, wherein the semiconductor switching element is constituted by a gate turn-off thyristor, and a current is interrupted by applying a reverse voltage between the gate and the cathode. It is.

A DC power transmission system using the DC cutoff device according to the seventeenth aspect of the present invention is provided on a first power transmission side, and a first converter for converting AC power for power transmission into DC power. A positive main line for transmitting only the positive side of the converted DC power to the power receiving side, a first inverter for converting the transmitted positive side DC power to AC power, and after being converted to AC power A first neutral wire that returns the DC current to the power transmission side and is grounded, and is disposed on the second power transmission side;
A second converter for converting the AC power for transmission to DC power, a negative main line for transmitting only the negative side of the converted DC power to the power receiving side, and an AC power source for transmitting the transmitted DC power on the negative side. A second inverter for converting the power to electric power, a second neutral line that is converted to AC power and returns a DC current to the power transmission side and grounded, and the first and second neutral lines. And a first and second return line protection circuit breaker provided between each neutral line and the ground, the first and second return lines being provided between the neutral line and ground. The circuit breaker according to claim 4, wherein at least one of the line protection circuit breaker and the neutral line protection circuit breaker is provided.
A three-terminal reverse blocking thyristor is connected in anti-parallel, and is constituted by a DC cutoff device for applying a reverse voltage to a main electrode of the three-terminal thyristor by current blocking means.

According to a twelfth aspect of the present invention, there is provided a DC power transmission system using a DC cutoff device, wherein a semiconductor switching element is provided in at least one of the neutral line protection circuit breaker and the first and second return line protection circuit breakers. Is constructed by a three-terminal reverse blocking thyristor and uses a DC cutoff device for cutting off the current by applying a reverse voltage to the main electrode by a current cutoff means.

According to a twelfth aspect of the present invention, there is provided a DC power transmission system using the DC cutoff device, wherein at least one of the neutral line protection circuit breaker and the first and second return line protection circuit breakers includes a semiconductor switching element. Is constituted by a gate turn-off thyristor, and a DC cut-off device for applying a reverse voltage by a current cut-off means between its gate and cathode to cut off the current is used.

According to a twentieth aspect of the present invention, there is provided a DC power transmission system using the DC interrupter, wherein at least one of the neutral line protection circuit breaker and the first and second return line protection circuit breakers has
A reverse current blocking three-terminal thyristor is connected in anti-parallel to form a bidirectional thyristor. is there.

According to a twelfth aspect of the present invention, there is provided a DC power transmission system using a DC cutoff device, wherein a capacitor charged by a DC voltage applied to a DC line and a charge / discharge terminal of the capacitor are connected to the semiconductor switching element from the DC line. A changeover switch for switching to a main electrode, and a current cutoff means for discharging a charging voltage of the capacitor to the main electrode and applying a reverse voltage when a DC current is cut off.

According to a twelfth aspect of the present invention, there is provided a DC power transmission system using a DC cutoff device, wherein a capacitor charged by a DC voltage applied to a DC line and a charge / discharge terminal of the capacitor are connected to the semiconductor switching side from the DC line. A first changeover switch for switching, and a second changeover switch for changing an output of the first changeover switch to a main electrode of each of the semiconductor switching elements connected in anti-parallel. There is provided a current interrupting means for switching the main electrode of the discharge destination of the charging voltage of the capacitor by a second changeover switch in accordance with the direction of the current to discharge and apply a reverse voltage.

According to a twelfth aspect of the present invention, there is provided a DC power transmission system using a DC cutoff device, wherein a capacitor charged by a DC voltage applied to a DC line and a charge / discharge terminal of the capacitor are connected to the gate turn-off thyristor by the DC power supply. A changeover switch for switching to a gate, and a current cutoff means for discharging a charging voltage of the capacitor to the gate and applying a reverse voltage between the gate and the cathode when the DC current is cutoff.

According to a twenty-fourth aspect of the present invention, there is provided a DC power transmission system using a DC cutoff device, wherein a capacitor charged by a DC power supply and a charge / discharge terminal of the capacitor are switched from the DC line to a main electrode of a semiconductor switching element. And a current interrupting means for applying a charging voltage of the capacitor as a reverse voltage to the main electrode when the DC current is interrupted.

According to a twenty-fifth aspect of the present invention, there is provided a DC power transmission system using a DC cutoff device, wherein a capacitor charged by a DC power supply and a first switch for switching a charge / discharge terminal of the capacitor from the DC line to a semiconductor switching side. A switch, and a second changeover switch for changing an output of the first changeover switch to a main electrode of each of the semiconductor switching elements connected in anti-parallel,
When the DC current is cut off, a current cut-off means is provided which switches the main electrode to which the charging voltage of the capacitor is discharged by the second changeover switch in accordance with the direction of the DC current to discharge and applies a reverse voltage. .

According to a twenty-sixth aspect of the present invention, there is provided a DC power transmission system using a DC cutoff device, wherein a capacitor charged by a DC power source and a switch for switching a charge / discharge terminal of the capacitor from the DC power source to a gate of a gate turn-off thyristor. And a current interruption means for discharging a charging voltage of the capacitor to the gate and applying a reverse voltage between the gate and the cathode when the DC current is interrupted.

In a DC power transmission system using a DC cutoff device according to a twenty-seventh aspect, one end of a reactor is connected to a capacitor and the other end is grounded.

A DC transmission system using the DC cutoff device according to the twenty-eighth aspect of the present invention is a system in which a transient overvoltage suppression element connected in parallel to a semiconductor switching element is connected in parallel.

[0050]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, the present embodiment will be described with reference to the drawings. FIG. 1 is a schematic diagram of a DC blocking device 10 using a reverse blocking three-terminal thyristor element according to a first embodiment. In FIG. 1, reference numeral 11 denotes a reverse blocking three-terminal thyristor element connected in series to a DC line. Reference numeral 13 denotes a DC power supply whose positive side is grounded and whose negative side is applied to the upstream side (anode) of the reverse blocking three-terminal thyristor element 11, and 14 denotes a bypass line connected in parallel to the reverse blocking three-terminal thyristor element 11. The switch S is inserted in the middle in the middle.
A switch 21 applies a reverse voltage to the upstream side of the DC line 19 from the negative electrode of the DC power supply 13.

Next, the operation (interruption process) of the DC interrupter 10 will be described. When the current of the DC line 19 flows through the DC cutoff device 10, the switch S of the bypass line 14 connected in parallel to the reverse blocking three-terminal thyristor element 11 is connected in order to prevent the reverse blocking three-terminal thyristor element 11 from overheating. Is turned on (ON), and a direct current is supplied to the bypass line 14.

In the shut-off process, first, the bypass line 14
Is turned on (OFF), and a gate signal (ON) is given to the gate of the reverse blocking three-terminal thyristor element 11 from a gate circuit (not shown) to make the reverse blocking three-terminal thyristor element 11 conductive (ON). In this state, the DC current flowing through the bypass line 14 is commutated to the reverse blocking three-terminal thyristor element 11 side. Next, in this state, the signal of the gate of the reverse blocking three-terminal thyristor element 11 is cut off (OF).
F), at this point, the DC current continues to flow through the reverse blocking three-terminal thyristor element 11.

Then, when the switch 21 is turned on (ON) and a reverse voltage is applied by the DC power supply 13, the DC current flowing through the reverse blocking three-terminal thyristor element 11 forcibly reaches the current zero point. At the current zero point, the reverse blocking three-terminal thyristor element 11 is turned off (OFF), and the DC current is cut off.

Embodiment 2 FIG. 2 is a schematic diagram of a bidirectional DC cutoff device 20 using a triac (bidirectional thyristor element) configured by connecting a reverse blocking three-terminal thyristor element (thyristor element) in reverse parallel according to the second embodiment. It is shown. In the drawing, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts. In FIG. 2, reference numeral 12 denotes a triac, and 22 denotes a switch that applies a DC voltage to the upstream or downstream side of the DC line 19 and applies a reverse voltage to each thyristor element included in the triac 12. Each stator of the switch 22 is connected to the upstream or downstream side of the DC line 19, and the mover is connected to the negative side of the DC power supply. Then, the mover is switched to one of the stators according to the direction in which the DC current flows in the DC line 19.

Next, the operation (interruption process) of the DC interrupter 20 will be described. When the current of the DC line 19 flows through the DC cutoff device 20, the switch S of the bypass line 14 connected in parallel with the triac 12 is turned on (ON) in order to prevent the triac 12 from overheating. DC current is supplied to the

In the shut-off process, first, the bypass line 14
The switch S is opened (OFF) and a gate signal (ON) is applied to the gate of any of the thyristor elements constituting the triac 12 in accordance with the direction in which the DC current flows, thereby turning on the thyristor element (ON). In this state, direct current is commutated to the triac side. Next, in this state, the gate signal of the thyristor element is turned off (OFF).
DC current continues to flow through triac 12.

Then, when the switch 22 is turned on (ON) and a reverse voltage is applied to the upstream or downstream of the triac 12 by the DC power supply 13 in accordance with the direction of the DC current flowing through the DC line 19, the triac 12 is turned on. The flowing DC current is forced to reach the current zero point. Therefore, at the current zero point, the thyristor element is turned off (OFF), and the DC current is cut off. That is, the DC cutoff device 20 can cut off the DC current flowing in the DC line 19 in either direction.

Embodiment 3 FIG. FIG. 3 is a schematic diagram of the DC power transmission system according to the present embodiment, and uses the DC interrupting device shown in FIGS. 1 and 2 as the DC interrupting device. In FIG. 3, 1 is a positive main line for transmitting a positive potential DC, 2 is a negative main line for transmitting a negative potential DC, 3
Reference numerals 4 and 4 denote a neutral line (return line) which is a return line of DC, 5 denotes a plurality of rectifiers (reverse blocking three-terminal thyristor valves, hereinafter referred to as thyristor valves), and 20 denotes two neutral lines 3.
2 and 4 is a neutral line protection circuit breaker using a DC interrupter using a triac 12 provided between the triac 12 and the triac 12, as shown in FIG. It comprises a power supply 13, a bypass line 14 having a switch S, and a switch 22.

Reference numeral 10 denotes a return line protection circuit breaker using a DC blocking device using a reverse blocking three-terminal thyristor element 11 provided between each of the neutral lines 3 and 4 and the ground. As shown in FIG. 1, the switch 10 has a reverse blocking three-terminal thyristor element 11 and a DC power supply 13.
, A bypass line 14 having a switch S, and a switch 2
1.

Next, the operation will be described. The operation of transmitting power using only the positive electrode side or the negative electrode side of this DC power transmission system is as described above. In a normal operation state using only one pole of such a DC transmission system, the return line protection circuit breaker 1 provided on the neutral conductors 3 and 4 is used.
0 is open (OFF).

When a short circuit accident occurs in the neutral wires 3 and 4,
The switch S of the bypass line 14 constituting the return line protection circuit breaker 10 is closed (ON), and the neutral lines 3 and 4 are grounded (earthed). After the insulation of the neutral wires 3 and 4 has been secured (the cause of the accident has been eliminated), the circuit breaker 10 for return line protection is connected to the circuit shown in FIG.
When the operation is performed in the same manner as the DC cutoff device described in the cutoff process based on, the DC current is cut off and the operation returns to the normal operation using only one pole.

The operation of transmitting power using both the positive electrode side and the negative electrode side of the DC power transmission system is as described above. In the normal operation state using both poles of the DC power transmission system, the switch S of the bypass line 14 of the neutral line protection circuit breaker 20 provided between the two neutral lines 3 and 4 is closed (ON), The return circuit protection circuit breakers 10 provided on the neutral wires 3 and 4 are open (OFF).

When an accident or the like occurs on the positive electrode side or the negative electrode side and it is necessary to switch to the unipolar operation, similarly to the DC cutoff device described in the cutoff process of the second embodiment, the neutral circuit protection circuit breaker 20 is used. Is operated, the direct current is cut off, and the positive electrode side and the negative electrode side are separated from each other.

Of course, as the return circuit protection circuit breaker 10, a DC circuit breaker 20 using a triac 12 in which reverse blocking three-terminal thyristor elements 11 are connected in anti-parallel may be used. As the line protection circuit breaker 20,
A DC circuit breaker 10 using a three-terminal reverse blocking thyristor element 11 may be used. This makes it possible to construct a DC power transmission system using a DC circuit breaker that does not use SF ₆ gas.

Embodiment 4 In the first to third embodiments, the DC power supply 13 for obtaining the reverse voltage is provided as an external power supply, but the reverse voltage may be obtained from the negative main line 2. Further, in order to protect the reverse blocking three-terminal thyristor element 11 from surge voltage, the reverse blocking three-terminal thyristor element 11 is protected.
A transient overvoltage suppression element (surge absorber) may be connected in parallel.

Hereinafter, the present embodiment will be described with reference to the drawings. FIG. 4 is a schematic diagram of a DC power transmission system including a DC circuit breaker using a reverse blocking three-terminal thyristor element. In the drawing, the same reference numerals as those in FIG. 3 indicate the same or corresponding parts. In FIG. 4, 10Aa represents two neutral wires 3 and 4.
This is a neutral line protection circuit breaker using a DC circuit breaker 10A using a reverse blocking three-terminal thyristor element 11 provided therebetween. This neutral line protection circuit breaker 10Aa is connected to a reverse blocking three-terminal thyristor element 11. , Bypass line 1 having switch S connected in parallel to three-terminal reverse blocking thyristor element 11
4 and a transient overvoltage suppression element (surge absorber) 1 also connected in parallel to the reverse blocking three-terminal thyristor element 11
5 is comprised.

10Ab is a return circuit protection circuit breaker using a DC circuit breaker 10A using a three-terminal reverse blocking thyristor element 11 provided on each of the neutral conductors 3 and 4, and this return circuit protection circuit breaker 10Ab. Is a reverse blocking three-terminal thyristor element 11, a bypass line 14 having a switch S connected in parallel to the reverse blocking three-terminal thyristor element 11, and a transient overvoltage suppression also connected in parallel to the reverse blocking three-terminal thyristor element 11. An element (surge absorber) 15 is provided.

Reference numeral 34 denotes each circuit breaker 10Aa, 10Ab
Are switches for applying a reverse voltage to the reverse blocking three-terminal thyristor element 11, and each stator of the switch 34 is connected to the reverse blocking three-terminal thyristor element 11 constituting the return line protection circuit breaker 10Ab. It is connected to the anode side and to the anode side and the cathode side of the reverse blocking three-terminal thyristor element 11 constituting the neutral line protection circuit breaker 10Aa. A reverse voltage is supplied to these stators while being switched by a mover.

Reference numerals 31 and 32 denote capacitors and reactors connected in series to the ground side of the negative electrode main line 2.
Is a drive switch connected to the charge / discharge terminal of the capacitor 31, one of the stators of the drive switch 33 is connected to the negative electrode main line 2, and the other is connected to the mover of the changeover switch 34. . The mover of the drive switch 33 is connected to the charge / discharge terminal of the capacitor 31.

Next, the operation will be described. The operation of transmitting power using only the positive electrode or the negative electrode of this DC power transmission system is as described above. In a normal operation state using only one pole of such a DC transmission system,
Return circuit protection circuit breaker 10A provided on neutral wires 3 and 4
b is open (OFF). When a short circuit fault occurs in the neutral wires 3 and 4, the switch S of the bypass line 14 of the DC circuit breaker 10A constituting the return line protection circuit breaker 10Ab
(ON), neutral wires 3 and 4 are grounded (earth)
Is done.

After the insulation of the neutral wires 3 and 4 has been secured (the cause of the accident has been eliminated), in the shut-off process, first, the bypass wire 1
4 is opened (OFF) and a signal (ON) is applied to the gate of the reverse blocking three-terminal thyristor element 11 to turn on the reverse blocking three-terminal thyristor element 11 (O).
In the state N), a direct current is commutated from the bypass line 14 to the reverse blocking three-terminal thyristor element 11 side. Next, in this state, the gate signal of the reverse blocking three-terminal thyristor element 11 is turned off (OFF), but the direct current continues to flow through the reverse blocking three-terminal thyristor element 11.

Therefore, the movable element of the changeover switch 34 is fixed to the reverse blocking three-terminal thyristor element 11 to which a reverse voltage is to be applied, to which the reverse voltage of the DC circuit breaker 10A constituting the return line protection circuit breaker 10Ab is cut off. Input to child (ON)
And put. Next, in order to apply a voltage to the capacitor 31 and the reactor 32 connected to the negative electrode main line 2, the drive switch 33 is turned on (ON) to the negative electrode main line 2 side to store electric energy in the capacitor 31.

Next, when the drive switch 33 is switched to the changeover switch 34 side, the return line protection circuit breaker 10Ab
The electric energy stored in the capacitor 31 is applied as a reverse voltage to the reverse blocking three-terminal thyristor element 11 of the DC circuit breaker 10A, and the DC current flowing through the reverse blocking three-terminal thyristor element 11 is forcibly applied. At the current zero point, the reverse blocking three-terminal thyristor element 11 is turned off (OFF) at this current zero point, and the DC current is cut off.

That is, since a reverse voltage is applied to the reverse blocking three-terminal thyristor element 11 using the negative electrode main line 2, a special external power supply is not required. In a normal operation state using both poles of such a DC power transmission system, the DC circuit breaker constituting the neutral line protection circuit breaker 10Aa provided between the two neutral lines 3 and 4 as described above. The switch S of the 10A bypass line 14 is closed (O
N). Also, a DC circuit breaker 10A constituting a return line protection circuit breaker 10Ab provided for the neutral conductors 3 and 4
Are open (OFF).

When an accident or the like occurs on the positive electrode side or the negative electrode side and it is necessary to switch to the unipolar operation, the switch S of the bypass line 14 of the DC circuit breaker 10A constituting the neutral circuit protection circuit breaker 10Aa is opened. (OFF), and at the same time, a signal (ON) is given to the gate of the reverse blocking three-terminal thyristor element 11 to make the reverse blocking three-terminal thyristor element 11 conductive (O).
In the state N), a DC current flowing through the bypass line 14 is commutated to the reverse blocking three-terminal thyristor element 11 side.

Next, in this state, the signal of the gate of the reverse blocking three-terminal thyristor element 11 is cut off (OFF), but direct current continues to flow through the reverse blocking three-terminal thyristor element 11. Therefore, the changeover switch 34 is turned on (ON) on the reverse blocking three-terminal thyristor element 11 side to which a reverse voltage is to be applied by the DC circuit breaker 10A constituting the neutral line protection circuit breaker 10Aa to be cut off.

Next, the drive switch 33 is turned on to the negative main line 2 (ON) to store electric energy in the capacitor 31 and the reactor 32. Next, when the drive switch 33 is switched to the changeover switch 34 side, the electric energy stored in the reverse blocking three-terminal thyristor element 11 of the DC circuit breaker 10A constituting the neutral line protection circuit breaker 10Aa is applied as a reverse voltage. Is done. As a result, the DC current flowing through the reverse blocking three-terminal thyristor element 11 forcibly reaches the current zero point. At this current zero point, the reverse blocking three-terminal thyristor element 11 is turned off (OFF), and the DC current is reduced. Is cut off, so that the positive electrode and the negative electrode are separated from each other.

Embodiment 5 FIG. FIG. 5 is a schematic diagram of a DC power transmission system including a DC breaker using a triac configured by combining two reverse blocking three-terminal thyristor elements (thyristor elements) in antiparallel connection. In the drawing, the same reference numerals as those in FIG. 4 indicate the same or corresponding parts.

In FIG. 5, 20Aa represents two neutral wires 3
And a triac 12 in which two reverse blocking three-terminal thyristor elements provided between the thyristor and the thyristor are connected in antiparallel.
This is a circuit breaker for neutral line protection by a DC circuit breaker 20A using the same. The circuit breaker 20Aa for neutral line protection comprises a triac 12, a bypass line 14 having a switch S, and a transient overvoltage suppression element (surge absorber) 15. Is done.

Reference numeral 20Ab designates a return circuit protection circuit breaker using a DC circuit breaker 20A using a three-terminal reverse blocking thyristor element 11 provided on each of the neutral conductors 3 and 4, and the return circuit protection circuit breaker 20Ab Is composed of a triac 12, a bypass line 14 having a switch S, and a transient overvoltage suppression element (surge absorber) 15.

Reference numeral 34 denotes a changeover switch for applying a reverse voltage to the triac 12 of each DC circuit breaker 20A. Reference numerals 31 and 32 are connected to the negative electrode main line 2, and capacitors for storing electric energy from the negative electrode main line 2. A reactor 33 is a drive switch for applying the electric energy stored in the capacitor 31 to the DC line of each triac 12 as a reverse voltage.

Next, the operation will be described. The operation of transmitting power using only the positive electrode side or the negative electrode side of this DC power transmission system is as described above. In a normal operation state using only one pole of such a DC power transmission system, the return line protection circuit breaker 2 provided on the neutral conductors 3 and 4
0Ab is open (OFF). Neutral wires 3 and 4
If a short circuit accident occurs on the return circuit breaker 20Ab
The switch of the bypass line 14 of the DC circuit breaker 20A is closed (ON) to ground the neutral lines 3 and 4.

After the insulation of the neutral wires 3 and 4 has been secured (the cause of the accident has been eliminated), in the shut-off process, first, the switch S of the bypass wire 14 is opened (OFF) and a signal is applied to the gate of the thyristor element. (ON) to make the triac 12 conductive (ON), and the DC current of the bypass line 14 is commutated to the thyristor side.

Next, in this state, the gate signal of the thyristor element is cut off (OFF), but the direct current continues to flow through one of the thyristor elements of the triac 12. Therefore, the changeover switch 34 is turned on (ON) to one of the thyristor elements of the triac 12 to which a reverse voltage is to be applied to the DC breaker 20A constituting the return line protection circuit breaker 20Ab to be cut off.

Next, in order to store electric energy in the capacitor 31 and the reactor 32 connected to the negative electrode main line 2, the drive switch 33 is turned on (ON) to the negative electrode main line 2, and the electric energy is supplied to the capacitor 31. To store. Next, when the drive switch 33 is switched to the changeover switch 34 side, electric energy is applied as a reverse voltage to one of the thyristor elements of the triac 12 of the DC breaker 20A constituting the return line protection breaker 20Ab.

As a result, the DC current flowing through one of the thyristor elements of the triac 12 forcibly reaches the current zero point. At this current zero point, the thyristor element is cut off (OFF), and the DC current is cut off. Is done.

That is, since a reverse voltage is applied to the triac 12 using the negative electrode main line 2, a special external power supply is not required. In a normal operation state using both poles of such a DC power transmission system, the DC circuit breaker constituting the neutral line protection circuit breaker 20Aa provided between the two neutral lines 3 and 4 as described above. The switch S of the bypass line 10 is closed, and the DC circuit breaker 20A constituting the return line protection circuit breaker 20Ab provided on the neutral lines 3 and 4 is opened (OFF). .

When an accident or the like occurs on the positive electrode side or the negative electrode side and it is necessary to switch to the unipolar operation, the switch S of the bypass line 14 of the DC breaker 20A constituting the neutral protective circuit breaker 20Aa is opened. (OFF), a gate signal (ON) is given to the thyristor element, and one of the thyristor elements of the triac 12 is turned on (ON), and the DC current of the bypass line 14 is commutated to the thyristor side.

Next, in this state, the signal (OFF) is cut off to the gate of the thyristor element, but the DC current continues to flow through one of the thyristor elements of the triac 12.
Therefore, the changeover switch 34 is turned on (ON) to one of the thyristor elements of the triac 12 to which a reverse voltage is to be applied by the DC circuit breaker 20A constituting the neutral line protection circuit breaker 20Aa to be cut off.

Next, in order to store electric energy in the capacitor 31 and the reactor 32 connected to the negative line 2, the drive switch 33 is turned on (ON) to the negative main line 2, and the electric energy is stored in the capacitor 31. To store. Next, when the drive switch 33 is switched to the changeover switch 34 side, electric energy is applied as a reverse voltage to one of the thyristor elements of the triac 12 of the DC breaker 20A constituting the neutral protective circuit breaker 20Aa. .

As a result, the DC current flowing through one of the thyristor elements of the triac 12 is forced to reach the current zero point. At this current zero point, the thyristor element is cut off (OFF) and the DC current is cut off. Therefore, pole separation between the positive electrode side and the negative electrode side is performed.

Embodiment 6 FIG. In the above-described third to fifth embodiments, the electric energy in which the reverse voltage to the semiconductor switching element forming the DC circuit breaker is stored in the capacitor 31 and the reactor 32 from the negative main line 2 is used. The electric energy stored in the capacitor 31 and the reactor 32 from the power supply may be used as a reverse voltage for the semiconductor switching element.

FIG. 6 is a schematic view of a DC circuit breaker 10B using a reverse blocking three-terminal thyristor element according to the present embodiment. In FIG. DC power supply, 14 is a bypass line having a switch connected in parallel with the reverse blocking three-terminal thyristor element 11, and 15 is a transient overvoltage suppression element (surge absorber) similarly connected in parallel with the reverse blocking three-terminal thyristor element 11. ), 16 and 17 are similarly capacitors and reactors provided in parallel with the reverse blocking three-terminal thyristor element 11, and 23 applies the voltage of the DC power supply 13 to the capacitors 16 and 17 and
And a drive switch for applying the electric energy stored in the reactor 17 to the DC line 19 as a reverse voltage.

Next, the operation (interruption process) of DC breaker 10B will be described. When the current of the DC line 19 flows through the DC circuit breaker 10B, the switch S of the bypass line 14 connected in parallel with the reverse blocking three-terminal thyristor element 11 is used to prevent overheating of the reverse blocking three-terminal thyristor element 11. Is turned on (ON), and a direct current is supplied to the bypass line 14.

In the shut-off process, first, the bypass line 14
Is opened (OFF), and a gate signal is supplied to the gate of the reverse blocking three-terminal thyristor element 11 (O
N) to turn on the reverse blocking three-terminal thyristor element 11 (O
In the state N), the direct current of the bypass line 14 is commutated to the reverse blocking three-terminal thyristor side. Next, in this state,
Gate signal (OF) of the reverse blocking three-terminal thyristor element 11
F) is cut off, but the direct current continues to flow through the reverse blocking three-terminal thyristor element 11.

On the other hand, the drive switch 23 is turned on (ON) to the DC power supply 13 side to cause the capacitor 16 to store electric energy. Next, the drive switch 23 is connected to the DC line 19.
(ON) to the condenser 16 and the reactor 1
The electric energy stored in 7 is applied as a reverse voltage. As a result, when a reverse voltage is applied to the reverse blocking three-terminal thyristor element 11, the DC current flowing through the reverse blocking three-terminal thyristor element 11 forcibly reaches the current zero point. The reverse blocking three-terminal thyristor element 11 is turned off (OFF), and the DC current is cut off.

At this time, since the transient overvoltage suppression element (surge absorber) 15 suppresses the overvoltage applied to the reverse blocking three-terminal thyristor element 11, the frequency of destruction of the reverse blocking three-terminal thyristor element 11 due to the surge is reduced. Decrease. Also, an appropriate capacitor 16 and a reactor 17
By selecting the capacitance, the slope of the rise of the gate current and its absolute value and timing can be controlled.

Embodiment 7 FIG. FIG. 7 is a schematic diagram of a bidirectional DC circuit breaker 20B using a triac configured by connecting thyristor elements in antiparallel as a semiconductor switching element. In FIG. 7, reference numeral 12 denotes a triac configured by connecting thyristor elements in antiparallel, 13 denotes a DC power supply, 14 denotes a bypass line having a switch S connected in parallel to the triac 12, and 15 similarly connects in parallel to the triac 12. Transient overvoltage suppression elements (surge absorbers) 16 and 17 are also triac 1
A capacitor and a reactor provided in parallel with 2;
Is a drive switch that applies a voltage to the capacitor 16 and the reactor 17 and outputs electric energy from the capacitor 16 and the reactor 17. Reference numeral 22 denotes a changeover switch for switching and applying the electric energy output from the drive switch 23 to the upstream side or the downstream side of the triac 12.

Hereinafter, the operation (interruption process) of DC breaker 20B will be described. When the current of the DC line 19 flows through the DC breaker 20B, the switch S of the bypass line 14 having the switch S connected in parallel with the triac 12 is used to prevent the triac 12 from overheating.
Is turned on (ON), and a direct current is supplied to the bypass line 14.

In the shut-off process, first, the bypass line 14
Switch S is opened (OFF), and a gate signal is applied to the gate of the thyristor element constituting the triac 12 to make the thyristor element conductive (ON).
The direct current of the bypass line 14 is commutated to the triac 12 side.

Next, in this state, the gate signal of the gate of the thyristor element is cut off (OFF), but the direct current continues to flow through the triac 12.

On the other hand, the drive switch 23 is turned on (ON) on the DC power supply 13 side, and a voltage is applied to the capacitor 16.
Next, the drive switch 23 is turned on to the DC line 19 side (O
N) Then, when a reverse voltage is applied to the upstream or downstream of the triac 12 depending on the direction of the direct current by discharging the electric energy stored in the capacitor 16 and the reactor 17, the triac 12 flows through the triac 12. Since the DC current forcibly reaches the current zero point, the thyristor element is turned off (OFF) at this current zero point,
DC current is cut off.

That is, the DC breaker 20B can cut off DC current in either direction. Further, at this time, the transient overvoltage suppression element (surge absorber) 15 suppresses the overvoltage applied to the thyristor element, so that the frequency at which the thyristor element is destroyed by the surge is reduced. Also, a suitable capacitor 16 and reactor 1
By selecting seven capacitors, it is possible to control the slope of the rise of the gate current and its absolute value and timing.

Embodiment 8 FIG. FIG. 8 is a schematic diagram of a DC power transmission system constituted by a DC circuit breaker using a thyristor element according to the present embodiment. In the drawing, the same reference numerals as those in FIG. 5 indicate the same or corresponding parts. In FIG. 8, reference numeral 20B denotes a neutral line protection circuit breaker using a DC circuit breaker using a triac provided between two neutral lines 3 and 4, and the neutral line protection circuit breaker 20B is a triac 12 , A DC power supply 13, a bypass line 14 having a switch S, and a transient overvoltage suppression element (surge absorber) 1
5, a capacitor 16 and a reactor 17, a changeover switch 22, and a drive switch 23.

Reference numeral 10B denotes a return line protection circuit breaker formed by a DC circuit breaker using a reverse blocking three-terminal thyristor element 11 provided on each of the neutral wires 3 and 4. This return line protection circuit breaker 10B Reverse blocking three-terminal thyristor element 11
, A DC power supply 13, and a bypass line 14 having a switch
And a transient overvoltage suppression element (surge absorber) 15;
Capacitor 16 and reactor 17, drive switch 2
3

Next, the operation will be described. The operation of transmitting power using only the positive electrode side or the negative electrode side of this DC power transmission system is as described above. In a normal operation state using only one pole of such a DC transmission system, the return line protection circuit breaker 1 provided on the neutral conductors 3 and 4 is used.
0B is open (OFF).

If a short circuit accident occurs in the neutral wires 3 and 4,
The switch of the bypass line 14 constituting the return line protection circuit breaker 10B is closed (ON), and the neutral lines 3 and 4 are grounded (earthed).

After the insulation of the neutral wires 3 and 4 has been secured (the cause of the accident has been eliminated), when the return circuit protection circuit breaker 10B is operated as described with reference to FIG. 6, the direct current is cut off and the unipolar Return to normal operation using only The operation of transmitting power using both the positive electrode and the negative electrode of the DC power transmission system is as described above.

In a normal operation state using both poles of such a DC power transmission system, the neutral line protection circuit breaker 20B provided between the two neutral lines 3 and 4 is a bypass line constituting the circuit breaker. The 14 switches S are closed (ON), and
Return circuit breaker 10B provided for neutral wires 3 and 4
Are open (OFF).

When it is necessary to switch to the unipolar operation due to an accident or the like on the positive electrode side or the negative electrode side, the neutral line protective circuit breaker 20B is operated as described in FIG.
The direct current is cut off, and the positive electrode and the negative electrode are separated from each other.

As a matter of course, as the return line protection circuit breaker 10B, a DC circuit breaker using a triac 12 in which reverse-blocking three-terminal thyristor elements are connected in anti-parallel may be used. Further, a DC circuit breaker using a blocking three-terminal thyristor element may be used as the neutral line protection circuit breaker 20B. This enables a DC power transmission system using a DC circuit breaker that does not use SF ₆ gas.

Embodiment 9 FIG. Hereinafter, the present embodiment will be described with reference to the drawings. FIG. 9 is a schematic diagram of a DC breaker 30 according to the present embodiment using a gate turn-off thyristor (GTO) element. In FIG.
O element, 13 is a DC power supply, 14 is a bypass line having a switch S connected in parallel to the GTO element 36, 15 is a transient overvoltage suppression element (surge absorber) also connected in parallel to the GTO element 36, 16 and 17 is also G
A capacitor and a reactor 24 provided in parallel with the TO element 36 are a drive switch for applying a voltage to the capacitor 16 and the reactor 17 from the DC power supply 13 and applying the electric energy stored in the capacitor to the DC line 19 as a reverse voltage. It is.

Next, the operation (interruption process) of DC breaker 30 will be described. When the current of the DC line 19 flows through the DC circuit breaker 30, the switch S of the bypass line 14 having the switch S connected in parallel with the GTO element 36 is turned on (ON) in order to prevent the GTO element 36 from overheating.
Then, a direct current is supplied to the bypass line 14.

In the shut-off process, first, the bypass line 14
Switch S is opened (OFF), a gate signal is applied to the gate of the GTO element 36 (ON) to make the GTO element 36 conductive (ON), and the DC current of the bypass line 14 is transferred to the GTO element 36 side. Let it flow. Next, in this state, the gate signal of the GTO element 36 is turned off (OFF).
The DC current continues to flow through the GTO element 36.

On the other hand, the drive switch 24 is turned on (ON) to the DC power supply 13 side to cause the capacitor 16 to store electric energy. Next, the drive switch 24 is turned on (ON) to the DC line 19 side, and the electric energy stored in the capacitor 16 and the reactor 17 is discharged, thereby achieving G
A reverse voltage is applied between the gate cathode of the TO element 36. When a reverse current of about 1/3 of the DC current to be cut off flows to the gate,
The GTO element 36 is turned off (OFF), and the DC current is cut off.

At this time, since the transient overvoltage suppression element (surge absorber) 15 suppresses the overvoltage applied to the GTO element 36, the frequency of destruction of the GTO element 36 due to the surge is reduced. Further, by selecting appropriate capacitances of the capacitor 16 and the reactor 17, it is possible to control the rising gradient of the gate current and its absolute value and timing.

Embodiment 10 FIG. FIG. 10 is a schematic diagram of a DC power transmission system constituted by a DC circuit breaker using the GTO element 36 according to the present embodiment. In the drawing, the same reference numerals as those in FIG. 8 indicate the same or corresponding parts. FIG.
At 0, reference numeral 30a denotes a neutral line protection circuit breaker using a DC circuit breaker 30A using a GTO element 36 provided between two neutral lines 3 and 4.
0a is a GTO element 36, a bypass line 14 having a switch S, and a transient overvoltage suppression element (surge absorber) 1
5.

Reference numeral 30b denotes a return line protection circuit breaker using a DC circuit breaker 30A using the GTO 36 provided on each of the neutral lines 3 and 4.
b denotes a GTO element 36, a bypass line 14 having a switch S, and a transient overvoltage suppression element (surge absorber) 15
It consists of.

Reference numerals 31 and 32 denote capacitors and reactors connected to the negative electrode main line 2 via a drive switch 33, and reference numeral 34 denotes a changeover switch for applying the electric energy stored in the capacitor 31 as a reverse voltage to the gate of the GTO element 36. .

Next, the operation will be described. The operation of transmitting power using only the positive electrode or the negative electrode of the DC power transmission system is as described above. In a normal operation state using only one pole of such a DC power transmission system, the return line protection circuit breaker 30b provided on the neutral conductors 3 and 4
Are open (OFF). When a short circuit accident occurs in the neutral lines 3 and 4, the switch of the bypass line 14 of the DC circuit breaker 30A constituting the return line protection circuit breaker 30b is closed (ON), and the neutral lines 3 and 4 are disconnected. Ground (earth).

After the insulation of the neutral wires 3 and 4 has been secured and the cause of the accident has been eliminated, in the shut-off process, first, the switch of the bypass wire 14 is opened (OFF) and the GTO is turned off.
A forward current is applied to the gate of the element 36 to make the GTO element 36 conductive (ON), and the DC current of the bypass line 14 is commutated to the GTO element 36 side.

Next, in this state, the gate signal of the GTO element 36 is turned off (OFF).
Keep flowing. Therefore, the DC circuit breaker 30 that constitutes the return line protection circuit breaker 30b that shuts off the changeover switch 34
At A, it is turned on (ON) on the gate side of the GTO element 36 to which a reverse voltage is to be applied.

Next, in order to cause the capacitor 31 and the reactor 32 connected to the negative electrode main line 2 to store electric energy, the drive switch 33 is turned on (ON) to the negative electrode main line 2 to store electric energy in the capacitor 31. Let it. Next, the drive switch 33 is changed to the changeover switch 34.
When switching to the side, the electric energy stored in the capacitor 31 is applied as a reverse voltage to the gate of the GTO element 36 of the DC circuit breaker 30A constituting the return line protection circuit breaker 30b. As a result, when a reverse current of about の of the current to be interrupted flows to the gate, the GTO element 36 shuts off (OF).
F) state, and the DC current is cut off.

In a normal operation state using both poles of such a DC power transmission system, as described above, the neutral protection circuit breaker 30 provided between the two neutral conductors 3 and 4 has already been described.
a, the switch S of the bypass line 14 of the DC circuit breaker 30A constituting the “a” is closed (ON), and the DC interruption constituting the return line protection circuit breaker 30b provided on the neutral conductors 3 and 4 is performed. The device 30A is open (OFF).

If it is necessary to switch to the unipolar operation due to an accident or the like on the positive electrode side or the negative electrode side, the bypass line 1 of the DC circuit breaker 30A constituting the neutral line protection circuit breaker 30a is used.
4 switch S is opened (OFF) and GTO3
A forward current is passed through the gate of No. 6 to make the GTO element 36 conductive (ON), and a direct current is commutated to the GTO element 36 side.

Next, in this state, the gate signal of the GTO element 36 is turned off (OFF).
Continue to flow 6. Therefore, the DC circuit breaker 3 constituting the neutral line protection circuit breaker 30a that shuts off the changeover switch 34
It is turned on (ON) on the gate side of the GTO element 36 to which a reverse voltage of 0 A is to be applied. Next, in order to store electric energy in the capacitor 31 and the reactor 32 connected to the negative electrode main line 2, the drive switch 33 is turned on (ON) to the negative electrode main line 2 to charge the capacitor 31.

Next, when the drive switch 33 is switched to the changeover switch 34 side, the electric energy stored in the capacitor 31 at the gate of the GTO element 36 of the DC circuit breaker 30A constituting the neutral line protection circuit breaker 30a is reversed. When applied as a voltage and a reverse current of about 1/3 of the current to be cut off flows, the GTO element 36 is cut off (OFF) and the DC current is cut off, so that the positive electrode side and the negative electrode side are separated from each other.

In the above embodiment, the GTO element 36 of the DC circuit breaker 30A constituting the neutral line protection circuit breaker 30a and the return line protection circuit breaker 30b allows the gate current to flow from the negative main line 2. Instead, the same operation can be performed by using a DC breaker 30 using an external power supply according to the invention of FIG.

Embodiment 11 FIG. In each of the above embodiments, the case where one thyristor such as the reverse blocking three-terminal thyristor 11, the triac 12, the GTO 36, or the like is used in each DC breaker has been described. However, as shown in FIG.
If the capacitors 2 and 36 are connected in series, the withstand voltage can be increased.

Further, if a plurality of reverse blocking three-terminal thyristors 11, triacs 12, or GTOs 36 are connected in parallel as shown in FIG. Further, if a plurality of reverse blocking three-terminal thyristors 11, triacs 12, or GTOs 36 are connected in series as shown in FIG. it can.

[0131]

According to the first aspect of the present invention, a semiconductor switching element serially connected to a DC line in a forward direction, current bypass means provided in parallel with the semiconductor switching element, and a current flowing through the semiconductor switching element Current interrupting means for applying a reverse voltage to the main electrode of the semiconductor switching element when shutting off, opening the current bypass means when interrupting the DC current flowing through the DC line, and applying a reverse voltage to the main electrode of the semiconductor switching element. In addition, since an off operation is performed, current does not need to flow through the semiconductor switching element for a long time, so that there is no need for a cooling means, and the device can be downsized.

According to the second aspect of the present invention, there is provided a semiconductor switching element connected in parallel in a reverse direction to a semiconductor switching element connected in a forward direction in series with a DC line,
Since the current switching means for applying a reverse voltage to each main electrode of these semiconductor switching elements is provided, there is an effect that the bidirectional DC current flowing through the DC line can be cut off in addition to the effect of the first aspect.

[0133] According to the invention of claim 3, and the semiconductor switching element in reverse-blocking three-terminal thyristor. Thus applying an inverse voltage by the current interrupting means to the main electrode, without using the SF ₆ gas There is an effect that direct current can be cut off at high speed by suppressing the occurrence of arc.

According to the fourth aspect of the present invention, each of the semiconductor switching elements connected in anti-parallel is constituted by a reverse blocking three-terminal thyristor, and a reverse voltage is applied to the main electrode by a current interrupting means. In addition to the effect of 3, the bidirectional DC current flowing through the DC line can be cut off.

According to the fifth aspect of the present invention, the semiconductor switching element is constituted by a gate turn-off thyristor, and a reverse bias voltage is applied between the gate and the cathode by the current cutoff means. This eliminates the necessity of flowing the cooling air, thereby eliminating the need for a cooling means, thereby making it possible to reduce the size of the apparatus and to perform the current interruption with low power.

According to the invention of claim 6, the current interrupting means switches the capacitor charged with the DC voltage applied to the DC line and the charge / discharge terminal of the capacitor from the DC line to the main electrode of the semiconductor switching element. A changeover switch for discharging the charging voltage of the capacitor to the main electrode and applying a reverse voltage when the DC current is interrupted, so that an external power supply for applying the reverse voltage can be eliminated, so that the apparatus can be downsized. This has the effect.

According to the seventh aspect of the present invention, the current cutoff means includes a capacitor charged with a DC voltage applied to the DC line and a first terminal for switching a charge / discharge terminal of the capacitor from the DC line to the semiconductor switching side. A changeover switch, and a second changeover switch for changing an output of the first changeover switch to a main electrode of each of the semiconductor switching elements connected in anti-parallel. Since the main electrode of the discharge destination of the charging voltage of the capacitor is switched and discharged to apply a reverse voltage, an external power supply for applying a reverse voltage can be made unnecessary in addition to the effect of claim 4, so that the device is required. There is an effect that the size can be reduced.

According to the eighth aspect of the present invention, the current cut-off means switches the capacitor charged with the DC voltage applied to the DC line and switches the charge / discharge terminal of the capacitor from the DC power source to the gate of the gate turn-off thyristor. A switch, and discharges the charging voltage of the capacitor to the gate when a DC current is cut off so as to apply a bias voltage between the gate and the cathode. There is an effect that the size can be reduced.

According to the ninth aspect of the present invention, the current interrupting means includes a capacitor charged by a battery, and a changeover switch for switching a charge / discharge terminal of the capacitor from the battery to a main electrode of a semiconductor switching element. Since the charging voltage of the capacitor is discharged to the main electrode and the reverse voltage is applied at the time of current interruption, there is an effect that a power supply for applying the reverse voltage can be secured despite the accident of the DC line. .

According to the tenth aspect of the present invention, the current cutoff means includes a capacitor charged by the battery, a first changeover switch for changing a charge / discharge terminal of the capacitor from the battery to the semiconductor switching side, And a second changeover switch for changing the output of the changeover switch to the main electrode of each of the semiconductor switching elements connected in anti-parallel. When the DC current is cut off, the charge voltage of the capacitor is changed according to the direction of the DC current. Since the main electrode of the discharge destination is switched to discharge and a reverse voltage is applied, a reverse voltage for applying a reverse voltage to each semiconductor switching element to cut off a DC current flowing to both sides despite the accident of the DC line. There is an effect that a power supply can be secured.

According to the eleventh aspect of the present invention, the current cutoff means includes a capacitor charged by a battery, and a changeover switch for switching a charge / discharge terminal of the capacitor from the DC power supply to a gate of a gate turn-off thyristor. When the current is cut off, the charging voltage of the capacitor is discharged to the gate and a reverse bias voltage is applied between the gate and the cathode. There is an effect that a power supply for the reverse voltage applied to the gate of the turn-off thyristor can be secured.

According to the twelfth aspect of the present invention, one end of the reactor is connected to the capacitor and the other end is grounded, so that the rising gradient of the gate current of the semiconductor switching element and the timing of its absolute value can be controlled. This has the effect.

According to the thirteenth aspect, the transient overvoltage suppression element connected in parallel to the semiconductor switching element has an effect of suppressing an overvoltage to the semiconductor switching element when a surge occurs.

According to the fourteenth aspect of the present invention, the first converter, which is arranged on the first power transmission side and converts AC power for transmission to DC power, includes only the positive side of the converted DC power. And a first inverter that converts the transmitted positive-side DC power to AC power, and returns a DC current to the power transmitting side after being converted to AC power. A first neutral line that is grounded, and a second converter that is disposed on the second power transmission side and converts AC power for transmission to DC power, and that only the negative side of the converted DC power is A negative main line for transmitting power to the power receiving side, and a second inverter for converting the transmitted DC power on the negative side to AC power;
A neutral protection circuit breaker provided between a first neutral wire and a second neutral wire that returns a DC current to the power transmission side after being converted into AC power and is grounded. And first and second return line protection circuit breakers provided between the neutral lines and ground, and the first and second return line protection circuit breakers and the neutral line protection breakers are provided. at least one of the vessels protection, since using DC circuit breaker according to the semiconductor switching element according to claim 1, which is miniaturized does not require cooling means of SF ₆ gas and the semiconductor switching element to suppress the arc during current interruption A DC power transmission system using a circuit breaker is possible.

According to the fifteenth aspect of the present invention, since the semiconductor switching element is constituted by a three-terminal reverse blocking thyristor, the DC current can be cut off at high speed without arc generation without using SF ₆ gas. is there.

According to the sixteenth aspect of the present invention, since the semiconductor switching element is constituted by the gate turn-off thyristor, it is not necessary to supply current to the semiconductor switching element for a long time, so that no cooling means is required, and the device can be reduced in size. There is an effect that current interruption can be performed with electric power.

According to the seventeenth aspect of the present invention, the first converter, which is arranged on the first power transmission side and converts AC power for transmission into DC power, includes only the positive side of the converted DC power. And a first inverter for converting the transmitted positive-side DC power to AC power, and returning the DC current to the power transmitting side after being converted to AC power. A first neutral line that is grounded, and a second converter that is disposed on the second power transmission side and converts AC power for transmission to DC power, and that only the negative side of the converted DC power is A negative main line for transmitting power to the power receiving side, and a second inverter for converting the transmitted DC power on the negative side to AC power;
A neutral protection circuit breaker provided between a first neutral wire and a second neutral wire that returns a DC current to the power transmission side after being converted into AC power and is grounded. And first and second return line protection circuit breakers provided between the neutral lines and ground, and the first and second return line protection circuit breakers and the neutral line protection breakers are provided. Claim 4 wherein at least one of the containers
The two reverse blocking three-terminal thyristors described in (1) are connected in reverse parallel, and the reverse blocking three-terminal thyristor is constituted by a DC breaker that applies a reverse voltage to the main electrode by a current blocking means. It is possible to provide a DC power transmission system using a miniaturized DC circuit breaker that does not require SF ₆ gas and a cooling means for semiconductor switching elements.

According to the eighteenth aspect of the present invention, the first and the second
Because at least one of the return line protection circuit breaker and the neutral line protection circuit breaker uses a DC circuit breaker using a three-terminal reverse blocking thyristor as a semiconductor switching element, the arc can be generated without using SF ₆ gas. There is an effect that the DC current can be cut off at high speed by suppressing generation.

According to the nineteenth aspect, the first and the second
As a DC breaker using a gate turn-off thyristor as a semiconductor switching element is used for at least one of the return line protection circuit breaker and the neutral line protection circuit breaker, current does not need to flow through the semiconductor switching element for a long time. Therefore, there is an effect that cooling means is not required, the device can be downsized, and current can be interrupted with low power.

According to the twentieth aspect, the first and the second
A bidirectional thyristor configured by connecting two reverse blocking three-terminal thyristors in anti-parallel to at least one of the return line protection circuit breaker and the neutral line protection circuit breaker was used as a DC circuit breaker. Therefore, there is an effect that bidirectional DC current flowing in the DC line can be cut off.

According to the twenty-first aspect of the present invention, there is provided a capacitor charged with a DC voltage applied to a DC line, and a changeover switch for changing a charge / discharge terminal of the capacitor from the DC line to a main electrode of a semiconductor switching element. In addition, when the DC current is cut off, the current supply means for discharging the charging voltage of the capacitor to the main electrode and applying a reverse voltage is provided, so that an external power supply for applying the reverse voltage can be eliminated, and the device can be downsized. There is.

According to the twenty-second aspect of the present invention, a capacitor charged with a DC voltage applied to a DC line, a first changeover switch for changing a charge / discharge terminal of the capacitor from the DC line to a semiconductor switching side, A second switch for switching an output of the first changeover switch to a main electrode of each of the semiconductor switching elements connected in anti-parallel;
And a current cut-off means for switching and discharging the main electrode of the discharge destination of the charging voltage of the capacitor according to the direction of the direct current when the direct current is interrupted, and applying a reverse voltage. Since an external power supply for applying a reverse voltage can be eliminated, the size of the device can be reduced.

According to the twenty-third aspect of the present invention, there is provided a capacitor charged with a DC voltage applied to a DC line, and a changeover switch for changing a charge / discharge terminal of the capacitor from the DC power source to a gate of a gate turn-off thyristor, A current interruption means for discharging a charging voltage of the capacitor to the gate and applying a reverse bias voltage between the gate and the cathode when the DC current is interrupted, so that an external power supply for applying a reverse voltage is not required, so that the apparatus can be downsized. There is an effect that can be made.

According to a twenty-fourth aspect of the present invention, there is provided a capacitor charged by a battery, and a changeover switch for changing a charge / discharge terminal of the capacitor from the battery to a main electrode of a semiconductor switching element. Since the current interruption means for applying the reverse voltage by discharging the charge voltage to the main electrode is provided, there is an effect that a power supply for applying the reverse voltage can be secured irrespective of the DC line accident.

According to the twenty-fifth aspect of the present invention, a capacitor charged by a battery, a first switch for switching a charge / discharge terminal of the capacitor from the battery to a semiconductor switching side, and an output of the first switch. And a second changeover switch for switching to the main electrode of each of the semiconductor switching elements connected in anti-parallel. When the DC current is interrupted, the main electrode to which the charging voltage of the capacitor is discharged according to the direction of the DC current flow Is switched to discharge and apply a reverse voltage.Therefore, a power supply for applying a reverse voltage to each semiconductor switching element for cutting off the DC current flowing to both sides despite the accident of the DC line is provided. There is an effect that it can be secured.

According to the twenty-sixth aspect of the present invention, there is provided a capacitor charged by a battery, and a changeover switch for switching a charge / discharge terminal of the capacitor from the battery to a gate of a gate turn-off thyristor. A current cut-off means for discharging a charging voltage to the gate and applying a reverse bias voltage between the gate and the cathode is provided, so that a voltage is applied to a gate of a gate turn-off thyristor for cutting off a DC current despite a DC line accident. There is an effect that a power supply for the reverse voltage can be secured.

According to the twenty-seventh aspect, since one end of the reactor is connected to the capacitor and the other end is grounded, it is possible to control the rising gradient of the gate current of the semiconductor switching element and the timing of its absolute value. is there.

According to the twenty-eighth aspect of the present invention, since the transient overvoltage suppressing element connected in parallel to the semiconductor switching element is connected in parallel, it is possible to suppress the overvoltage to the semiconductor switching element when a surge occurs.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a DC blocking device according to Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram of a DC blocking device according to Embodiment 2 of the present invention.

FIG. 3 is a configuration diagram of a DC power transmission system according to Embodiment 3 of the present invention.

FIG. 4 is a configuration diagram of a DC power transmission system using a DC blocking device according to Embodiment 4 of the present invention.

FIG. 5 is a configuration diagram of a DC power transmission system using a DC blocking device according to Embodiment 5 of the present invention.

FIG. 6 is a configuration diagram of a DC cutoff device according to Embodiment 6 of the present invention.

FIG. 7 is a configuration diagram of a DC cutoff device according to Embodiment 7 of the present invention.

FIG. 8 is a configuration diagram of a DC power transmission system using a DC blocking device according to an eighth embodiment of the present invention.

FIG. 9 is a configuration diagram of a DC cutoff device according to Embodiment 9 of the present invention.

FIG. 10 is a configuration diagram of a DC power transmission system using a DC blocking device according to Embodiment 10 of the present invention.

FIG. 11 is a diagram showing a state in which a plurality of reverse blocking three-terminal thyristors according to Embodiment 11 of the present invention are connected.

FIG. 12 is a configuration diagram of a DC power transmission system using a conventional DC cutoff device.

[Explanation of symbols]

1 Positive wire, 2 Negative wire, 3, 4 Neutral wire, 5 Thyristor valve, 10, 10 Ab, 20 Ab, 10 B, 30
b Circuit breaker for neutral protection, 20, 10Aa, 20Aa,
20B, 30a Return circuit protection circuit breaker, 11 reverse blocking three-terminal thyristor, 12 triac, 13 DC power supply, 14 bypass line, 15 surge absorber, 31
Capacitor, 32 reactor, 34 changeover switch, 33 drive switch, 36 GTO.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroki Ito 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Kenji Kamei 2-3-2 Marunouchi 3-chome, Chiyoda-ku, Tokyo Inside Ryo Denki Co., Ltd. (72) Inventor Sueshin Hamano 2-3-2 Marunouchi, Chiyoda-ku, Tokyo San-Bi Electric Co., Ltd. (72) Etsuo Nitta 2-3-2 Marunouchi, Chiyoda-ku, Tokyo 3 Inside Rishi Electric Co., Ltd. (72) Manabu Shikata 3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Inside Kansai Electric Power Co., Inc. (72) Yoshihiko Chuetsu 2-5 Marunouchi, Takamatsu City, Kagawa Prefecture Shikoku Electric Power Company In-company (72) Inventor Masayuki Hatano 6-15-1, Ginza, Chuo-ku, Tokyo Inside Power Development Co., Ltd.

Claims (28)

[Claims] A semiconductor switching element connected in series to a DC line in a forward direction; a current bypass means provided in parallel with the semiconductor switching element; Current interrupting means for applying a reverse voltage to the main electrode, wherein when the DC current flowing through the DC line is interrupted, the current bypass means is opened, and the semiconductor switching element is turned off by applying a reverse voltage to the main electrode. DC blocking device. 2. A current cutoff means comprising a semiconductor switching element connected in parallel in the reverse direction to a semiconductor switching element connected in series in the DC line in the forward direction, and applying a reverse voltage to each main electrode of the semiconductor switching elements. The direct current cut-off device according to claim 1, further comprising: 3. The direct current cutoff device according to claim 1, wherein the semiconductor switching element is constituted by a reverse blocking three-terminal thyristor, and a reverse voltage is applied to a main electrode of the thyristor by a current cutoff means. 4. The direct current cutoff according to claim 2, wherein each of the semiconductor switching elements connected in antiparallel is constituted by a reverse blocking three-terminal thyristor, and a reverse voltage is applied to a main electrode of the thyristor by current cutoff means. apparatus. 5. A semiconductor switching device comprising a gate turn-off thyristor, wherein a reverse voltage is applied between the gate and the cathode by a current cutoff means.
The direct-current cut-off device according to 1. 6. The current interrupting means includes a capacitor charged with a DC voltage applied to a DC line, and a changeover switch for switching a charge / discharge terminal of the capacitor from the DC line to a main electrode of a semiconductor switching element. 2. A reverse voltage is applied by discharging a charge voltage of said capacitor to said main electrode when current is cut off.
Or the direct current cut-off device according to 3. 7. The current interrupting means includes: a capacitor charged with a DC voltage applied to a DC line; a first switch for switching a charge / discharge terminal of the capacitor from the DC line to a semiconductor switching element side; 1
And a second changeover switch for changing the output of the changeover switch to the main electrode of each of the semiconductor switching elements connected in anti-parallel. When the DC current is cut off, the charge voltage of the capacitor is changed according to the direction of the DC current. 3. The method according to claim 2, wherein the main electrode of the discharge destination is switched by the second switch to discharge and apply a reverse voltage.
Or the direct current cut-off device according to 4. 8. The current cutoff means includes a capacitor charged with a DC voltage applied to a DC line, and a changeover switch for switching a charge / discharge terminal of the capacitor from the DC power supply to a gate of a gate turn-off thyristor,
6. The DC cutoff device according to claim 5, wherein when the DC current is cut off, the charging voltage of the capacitor is discharged to the gate to apply a reverse voltage between the gate and the cathode. 9. The current cutoff means includes a capacitor charged by a battery, and a changeover switch for changing a charge / discharge terminal of the capacitor from the DC line to a main electrode of a semiconductor switching element. 4. The DC cutoff device according to claim 1, wherein a reverse voltage is applied by discharging a charging voltage to the main electrode. 10. The current cutoff means includes a capacitor charged by a battery, a first switch for switching a charge / discharge terminal of the capacitor from the DC line to a semiconductor switching side, and an output of the first switch. A second changeover switch for switching to the main electrode of each of the semiconductor switching elements connected in anti-parallel, and when the DC current is cut off, the discharge destination main electrode of the capacitor is charged according to the direction of the DC current. The second
The direct current cut-off device according to claim 2 or 4, wherein the switching is performed by a changeover switch to discharge and apply a reverse voltage. 11. The current interrupting means includes a capacitor charged by a battery, and a changeover switch for switching a charge / discharge terminal of the capacitor from the DC power supply to a gate of a gate turn-off thyristor, and charges the capacitor when DC current is interrupted. The direct current cutoff device according to claim 5, wherein a voltage is discharged to the gate to apply a reverse voltage between the gate and the cathode. 12. The capacitor according to claim 5, wherein one end of the reactor is connected to the capacitor, and the other end is grounded.
The direct current cutoff device according to any one of the above. 13. The direct current cutoff device according to claim 1, wherein a transient overvoltage suppression element connected in parallel to the semiconductor switching element is connected in parallel. 14. A first converter arranged on a first power transmission side for converting AC power for transmission to DC power, and transmitting only a positive side of the converted DC power to a power receiving side. A positive main line, a first inverter for converting the transmitted DC power on the positive electrode side to AC power, and a first inverter for converting the DC current to AC power and returning the DC current to the power transmission side to ground.
And a second converter arranged on the second power transmission side for converting AC power for transmission to DC power, and transmitting only the negative side of the converted DC power to the power receiving side. A negative main line, a second inverter that converts the transmitted DC power on the negative electrode side into AC power, and a second ground that returns the DC current to the power transmission side after being converted to AC power and grounds the DC power. A neutral conductor, a neutral protective circuit breaker provided between the first and second neutral conductors, and first and second return lines provided between the neutral conductors and ground. And a circuit breaker for protection.
And a DC breaker using the semiconductor breaker according to claim 1 for at least one of the second return line protection breaker and the neutral protection breaker. DC power transmission system used. 15. The semiconductor switching device according to claim 14, wherein the semiconductor switching element is constituted by a three-terminal reverse blocking thyristor, and a current is cut off by applying a reverse voltage to a main electrode of the semiconductor switching element by means of a current blocking means. DC power transmission system using a DC blocking device. 16. The direct current according to claim 14, wherein the semiconductor switching element is constituted by a gate turn-off thyristor, and a current is cut off by applying a reverse voltage between the gate and the cathode by a current cut-off means. DC power transmission system using a breaking device. 17. A first converter arranged on a first power transmission side for converting AC power for transmission to DC power, and transmitting only a positive side of the converted DC power to a power receiving side. A positive main line, a first inverter for converting the transmitted DC power on the positive electrode side to AC power, and a first inverter for converting the DC current to AC power and returning the DC current to the power transmission side to ground.
And a second converter arranged on the second power transmission side for converting AC power for transmission to DC power, and transmitting only the negative side of the converted DC power to the power receiving side. A negative main line, a second inverter that converts the transmitted DC power on the negative electrode side into AC power, and a second ground that returns the DC current to the power transmission side after being converted to AC power and grounds the DC power. A neutral conductor, a neutral protective circuit breaker provided between the first and second neutral conductors, and first and second return lines provided between the neutral conductors and ground. And a circuit breaker for protection.
5. The two reverse blocking three-terminal thyristors according to claim 4, wherein at least one of the second return line protection circuit breaker and the neutral line protection circuit breaker is connected in reverse parallel. A DC power transmission system using a DC interrupter, comprising a DC interrupter for applying a reverse voltage to a main electrode of a terminal thyristor by a current interrupter. 18. A three-terminal reverse blocking thyristor is used as a semiconductor switching element in at least one of the neutral circuit protection circuit breaker and the first and second return line protection circuit breakers, and the main electrode has current interruption means. 18. A DC power transmission system using the DC interrupting device according to claim 17, wherein a DC interrupting device that applies a reverse voltage to interrupt the current is used. 19. A semiconductor device comprising a gate turn-off thyristor as a semiconductor switching element and at least one of the neutral line protection circuit breaker and the first and second return line protection circuit breakers, wherein a current interrupting means is provided between the gate and the cathode. 18. The DC power transmission system using the DC interrupting device according to claim 17, wherein a DC interrupting device that interrupts current by applying a reverse voltage is used. 20. A bidirectional thyristor in which two reverse blocking three-terminal thyristors are connected in anti-parallel to at least one of the neutral line protection circuit breaker and the first and second return line protection circuit breakers. 18. A DC power transmission system using the DC interrupting device according to claim 17, wherein a DC interrupting device configured to apply a reverse voltage to the main electrodes by a current interrupting device to interrupt the current is used. . 21. A capacitor charged with a DC voltage applied to a DC line, and a changeover switch for changing a charge / discharge terminal of the capacitor from the DC line to a main electrode of a semiconductor switching element, wherein the capacitor is connected when DC current is cut off. 19. The DC power transmission system using the DC cutoff device according to claim 14, further comprising a current cutoff unit that discharges the charging voltage to the main electrode and applies a reverse voltage. 22. A capacitor charged by a DC voltage applied to a DC line, a first switch for switching a charge / discharge terminal of the capacitor from the DC line to a semiconductor switching side, and an output of the first switch. And a second changeover switch for switching to the main electrode of each of the semiconductor switching elements connected in anti-parallel. When the DC current is interrupted, the main electrode to which the charging voltage of the capacitor is discharged according to the direction of the DC current flow 18. A current cut-off means for switching and discharging by a second changeover switch and applying a reverse voltage.
Or a DC power transmission system using the DC cutoff device according to 20. 23. A capacitor charged with a DC voltage applied to a DC line, and a changeover switch for changing a charging / discharging terminal of the capacitor from the DC power supply to a gate of a gate turn-off thyristor, wherein the capacitor is connected when DC current is cut off. 20. The DC power transmission system according to claim 16 or 19, further comprising current interrupting means for discharging a charging voltage to the gate and applying a reverse voltage between the gate and the cathode. 24. A capacitor charged by a battery, and a changeover switch for switching a charging / discharging terminal of the capacitor from the DC line to a main electrode of a semiconductor switching element, wherein when a DC current is cut off, the charging voltage of the capacitor is changed to the main voltage. 16. A device according to claim 14, further comprising a current interrupting means for applying a reverse voltage by discharging to the electrode.
19. A DC power transmission system using the DC cutoff device according to any one of 18. 25. A capacitor charged by a battery, a first changeover switch for changing a charge / discharge terminal of the capacitor from the DC line to a semiconductor switching side, and an output of the first changeover switch connected in anti-parallel. A second changeover switch for changing over to a main electrode of each of the semiconductor switching elements, wherein when the DC current is cut off, the main electrode of the discharge destination of the charging voltage of the capacitor is changed to the second changeover in accordance with the direction of DC current supply. 21. The DC power transmission system using the DC cutoff device according to claim 17, further comprising a current cutoff means for switching and discharging by a switch and applying a reverse voltage. 26. A capacitor charged by a battery, and a changeover switch for switching a charging / discharging terminal of the capacitor from the DC power supply to a gate of a gate turn-off thyristor, wherein a charging voltage of the capacitor is applied to the gate when DC current is cut off. 20. The DC power transmission system using the DC interrupting device according to claim 16, further comprising a current interrupting unit that discharges and applies a reverse voltage between the gate and the cathode. 27. A DC power transmission system using the DC cutoff device according to claim 21, wherein one end of the reactor is connected to the capacitor, and the other end is grounded. 28. A DC power transmission system using a DC cutoff device according to claim 14, wherein a transient overvoltage suppression element connected in parallel to the semiconductor switching element is connected in parallel.