WO2018198552A1

WO2018198552A1 - Direct current shut-down device

Info

Publication number: WO2018198552A1
Application number: PCT/JP2018/009367
Authority: WO
Inventors: 一伸大井; 伸仁上栗; 裕吾只野; 修治中村; 健太高所
Original assignee: 株式会社明電舎
Priority date: 2017-04-27
Filing date: 2018-03-12
Publication date: 2018-11-01

Abstract

In this invention, first and second mechanical circuit breakers CB1, CB2 are connected between a plus terminal from a first direct current system 1 and a plus terminal from a second direct current system 2. One end from a first semiconductor switching element T1 is connected to a connection point shared by the plus terminal from the first direct current system 1 and the first mechanical circuit breaker CB1. One end from a second semiconductor switching element T2 is connected to another end from the first semiconductor switching element T1. Another end from the second semiconductor switching element T2 is connected to the plus terminal from the second direct current system 2. A capacitor C is connected between the connection point shared by the first and second mechanical circuit breakers CB1, CB2 and the connection point shared by the first and second semiconductor switching elements T1, T2. A first reactor L1 is connected in series to the capacitor C. An impedance is connected between the connection point shared by the first and second semiconductor switching elements T1, T2 and the minus terminals from the first and second direct current systems 1, 2. In this direct current shut-down device the shutting down of current in both directions is reliably ensured without increasing the capacity of the capacitor.

Description

DC blocking device

TECHNICAL FIELD The present invention relates to a direct current cut-off device which can shut off direct current in both directions with small power loss in steady state.

The AC interrupting device for interrupting the alternating current is energized since it functions as a conductor when the mechanical circuit breaker is closed (in steady state), and opens the mechanical circuit breaker when an accident occurs. An arc is generated when the mechanical circuit breaker is opened, but since the arc can be extinguished at the current zero point, the current can be interrupted.

In addition, no current flows because the cutoff state functions as an insulator. The AC circuit breaker mainly uses a gas circuit breaker or a vacuum circuit breaker, and although a medium for arc extinguishing is different, both adopt a method for extinguishing the arc at a current zero point.

However, in the case of a direct current shutoff device which shuts off a direct current, unlike the alternating current, no current zero point occurs, so that the arc generated at the opening of the machine breaker can not be extinguished, resulting in damage or interruption failure of the contact.

Therefore, the DC interrupting device requires an auxiliary circuit or the like for generating a current zero point. Patent Document 1 is disclosed as a shutoff method provided with such an auxiliary circuit. The device of Patent Document 1 is configured to cope with unidirectional current interruption.

In a networked direct current transmission and distribution system, such as utilization of renewable energy and stable power supply and demand, bidirectional current interruption technology is required because bidirectional current may flow in one path. .

The configuration of the auxiliary circuit for diverting the current in Patent Document 1 is a capacitor and a diode. However, a voltage drop occurs when current passes through the diode. If this voltage drop is greater than the arc maintenance voltage, current will continue to flow through the open machine breaker and the arc can not be extinguished, causing a current interruption failure.

In particular, when applied to a high voltage system, if a diode with a high withstand voltage or a plurality of diodes are connected in series, the voltage drop in the diode becomes large, and the possibility of failure to interrupt the current increases.

Furthermore, in addition to the diode, the auxiliary circuit has a parasitic resistance and a parasitic inductance component, and it is difficult to divert all the current to the auxiliary circuit at the same time as opening the mechanical circuit breaker. When a little time has passed since the opening, the current diverted only partially from the mechanical circuit breaker flows in the auxiliary circuit to charge the capacitor, and the sum of the capacitor voltage and the voltage drop of the diode voltage is applied to the mechanical circuit breaker , Arc extinction becomes difficult.

FIG. 40 shows the operation that causes the problem. FIG. 40 (a) is a circuit diagram in which only elements relevant to interrupting the short circuit current of the second DC system 2 are extracted from the DC interrupting device, and parasitic inductance is added to the auxiliary circuit.

FIG. 40 (b) is a time chart showing each waveform when the voltage drop and the inductance of the diode in the auxiliary circuit are ignored. When the mechanical circuit breaker CB is opened at time t1, only the capacitor voltage is applied to the voltage Vcb across the mechanical circuit breaker, and the voltage is zero at time t1. Therefore, no arcing occurs and all the current is diverted to the auxiliary circuit, and the current can be cut off.

FIG. 40 (c) is a time chart showing each waveform when the voltage drop and the inductance of the diode in the auxiliary circuit are taken into consideration. At time t1, in addition to the capacitor voltage of the auxiliary circuit, the sum of the voltage drop of the diode and the parasitic inductance voltage is applied to the voltage Vcb across the mechanical circuit breaker. Also, due to the parasitic inductance, the auxiliary circuit current Iaux increases with a finite slope, and the mechanical circuit breaker passing current Icb also decreases with the same slope.

After time t1, the capacitor C is charged by the auxiliary circuit current Iaux, and the voltage Vcb across the machine breaker further increases. Here, if the voltage Vcb across the mechanical circuit breaker exceeds the arc holding voltage before the mechanical circuit breaker passing current Icb becomes sufficiently small (in FIG. 40, time t2), the arc can not be extinguished, and the current is the mechanical circuit breaker CB. Continue to pass and fail to shut off. Also, if a plurality of diodes D are connected in series for a high voltage system, the risk of exceeding the arc holding voltage is increased.

As a countermeasure, there is a method of increasing the capacity of the capacitor of the auxiliary circuit and gradually increasing the voltage at the opening of the mechanical circuit breaker. However, this only reduces the increase amount of voltage Vcb across mechanical circuit breaker after time t1 in FIG. 40, and there is no effect of reducing the increase of voltage Vcb across mechanical circuit breaker at time t1. In addition, there is also a problem that cost and device volume increase when the capacitor capacity is increased.

As described above, it is an object of the direct current cut-off device to cut off bidirectional current more reliably without increasing the capacity of the capacitor.

JP, 2016-28378, A Patent No. 6049957

The present invention has been made in view of the above-mentioned conventional problems, and one aspect thereof is characterized in that the first, the fourth, and the third connected in series between the + terminal of the first DC system and the + terminal of the second DC system. A first auxiliary circuit current switch unit having two mechanical circuit breakers and a first semiconductor switching element, and one end connected to a common connection point of the positive terminal of the first DC system and the first mechanical circuit breaker; 2 has a semiconductor switching element, one end is connected to the other end of the first auxiliary circuit current switch portion, and the other end is connected to the common connection point of the + terminal of the second DC system and the second mechanical circuit breaker A second auxiliary circuit current switch portion, a capacitor connected between a common connection point of the first and second mechanical circuit breakers and a common connection point of the first and second auxiliary circuit current switch portions; A first reactor connected in series to a capacitor, and the first and second Characterized in that and a impedance connected between the terminals - a common connection point between said first, second DC system circuit current switch unit.

Further, as one aspect thereof, the impedance is a resistor.

In one aspect, the first and second semiconductor switching elements are thyristors.

Further, as another aspect, the first and second auxiliary circuit current switch parts have diodes connected in series to the first and second semiconductor switching elements, and the first and second semiconductor switching elements are It is characterized by having a self-extinguishing ability.

In one embodiment, a Zener diode is connected between the resistor and the negative terminals of the first and second DC systems.

Further, according to another aspect, a third semiconductor switching element is connected between the resistor and the negative terminals of the first and second DC systems.

In another aspect, the impedance is a second reactor, and between a diode connected in parallel to the second reactor, the second reactor, and negative terminals of the first and second DC systems. And a third semiconductor switching element connected.

Further, as another aspect, it has first and second mechanical circuit breakers connected in series between the negative terminal of the first DC system and the negative terminal of the second DC system, and the first semiconductor switching element, It has a first auxiliary circuit current switch unit whose one end is connected to the common connection point of the first DC circuit negative terminal and the first mechanical circuit breaker, and a second semiconductor switching element, and the first auxiliary circuit current switch unit A second auxiliary circuit current switch unit having one end connected to the other end and the other end connected to the common connection point of the second terminal of the second DC system and the second mechanical circuit breaker; A capacitor connected between a common connection point of the mechanical circuit breaker and a common connection point of the first and second auxiliary circuit current switch parts, a first reactor connected in series to the capacitor, the first and second 2 Common connection point of the auxiliary circuit current switch section and the first A connection impedance between the positive terminal of the second DC system, characterized by comprising a.

Further, as one aspect thereof, when a current flows from the first DC system to the second DC system, and an accident occurs in the second DC system, the first semiconductor switching element is turned on, and (1) After the current flowing through the mechanical circuit breaker becomes lower than a predetermined value, the first mechanical circuit breaker is shut off, and current flows from the second direct current system to the first direct current system, and the first direct current system When an accident occurs, the second semiconductor switching element is turned on, and after the current flowing through the second mechanical circuit breaker becomes a predetermined value or less, the second mechanical circuit breaker is shut off.

Further, as one aspect thereof, an anode is connected to a common connection point of the first and second mechanical circuit breakers, and a cathode is connected to a common connection point of the first mechanical circuit breaker and the first auxiliary circuit current switch portion. An anode is connected to a common connection point of the third diode and the first and second mechanical circuit breakers, and a cathode is connected to a common connection point of the second mechanical circuit breaker and the second auxiliary circuit current switch unit. And a fourth diode.

Further, as one aspect thereof, when a current flows from the first direct current system to the second direct current system and a short circuit occurs in the second direct current system, the first semiconductor switching element is turned on to be an auxiliary circuit. A current flows, and the first mechanical circuit breaker is shut off in a period during which the auxiliary circuit current is greater than the short circuit current, a current flows from the second DC system to the first DC system, and the first DC system When a short circuit occurs, the second semiconductor switching element is turned on to flow an auxiliary circuit current, and the second mechanical circuit breaker is disconnected in a period during which the auxiliary circuit current is larger than the short circuit current.

In another aspect, the first and second mechanical circuit breakers are connected in parallel with fourth and fifth semiconductor switching elements having a self-extinguishing ability.

Further, as one aspect thereof, when a current flows from the first DC system to the second DC system and a short circuit occurs in the second DC system, the fourth semiconductor switching element is turned on, An opening command of the first mechanical circuit breaker is issued, and then the first semiconductor switching element is turned on, and current flows from the second DC system to the first DC system, and a short circuit occurs in the first DC system. When it occurs, after the fifth semiconductor switching device is turned on, an opening command of the second mechanical circuit breaker is issued, and then the second semiconductor switching device is turned on.

In another aspect, the semiconductor switching device does not have a self-extinguishing ability that is antiparallel connected to the third diode and does not have self-extinguishing ability that is antiparallel connected to the fourth diode. And a seventh semiconductor switching element.

Further, as one aspect thereof, when a current flows from the first direct current system to the second direct current system and a short circuit occurs in the second direct current system, the sixth semiconductor switching element is turned on; The opening instruction of the first mechanical circuit breaker is performed, and then the OFF instruction of the sixth semiconductor switching element is performed, and then the first semiconductor switching element is turned ON, and the second direct current system to the first direct current system When current flows and a short circuit occurs in the first DC system, the seventh semiconductor switching device is turned on, and then an opening command of the second mechanical circuit breaker is issued, and then the seventh semiconductor switching is performed. A command to turn off the element is issued, and then the second semiconductor switching element is turned on.

As another aspect, a cathode is connected to a common connection point of the first and second mechanical circuit breakers, and an anode is connected to a common connection point of the first mechanical circuit breaker and the first auxiliary circuit current switch unit. A cathode is connected to a common connection point of the third diode and the first and second mechanical circuit breakers, and an anode is connected to a common connection point of the second mechanical circuit breaker and the second auxiliary circuit current switch unit. And a fourth diode.

In another aspect, the mechanical circuit breaker connected between the + terminal of the first DC system and the + terminal of the second DC system, the common connection of the + terminal of the first DC system and the mechanical circuit breaker A third capacitor and a third auxiliary circuit current switch unit, or a first capacitor, a third reactor, and a third auxiliary circuit, which are sequentially connected in series between the point and the positive terminal of the second DC system and the common connection point of the mechanical circuit breaker The common connection point of the reactor, the first capacitor, the third auxiliary circuit current switch portion, the positive terminal of the second DC system and the mechanical circuit breaker, and the common connection of the positive terminal of the first DC system and the mechanical circuit breaker A second capacitor, a fourth reactor, and a fourth auxiliary circuit current switch unit sequentially connected in series between the points; or a fourth reactor, a second capacitor, and a fourth auxiliary circuit current switch unit, and the third reactor And the third auxiliary circuit A first impedance connected between the common connection point of the flow switch unit or the common connection point of the first capacitor and the third auxiliary circuit current switch unit, and the-terminals of the first and second DC systems. A common connection point of the fourth reactor and the fourth auxiliary circuit current switch unit, or a common connection point of the second capacitor and the fourth auxiliary circuit current switch unit, and the first and second DC systems And-a second impedance connected between the terminal and the terminal.

In one aspect, the first impedance and the second impedance are a first resistance and a second resistance.

In one embodiment, the third auxiliary circuit current switch unit includes an eighth semiconductor switching device of a self-arc-extinguishing device and a fifth diode connected in series to the eighth semiconductor switching device; The fourth auxiliary circuit current switch unit includes a ninth semiconductor switching element of a self-arc-extinguishing type element and a sixth diode connected in series to the ninth semiconductor switching element.

In another aspect, the third auxiliary circuit current switch unit includes an eighth semiconductor switching element having no self arc extinguishing capability, and the fourth auxiliary circuit current switch unit has a self arc extinguishing capability. A ninth semiconductor switching device is provided.

In one embodiment, the semiconductor device further includes a tenth semiconductor switching element connected between the first and second resistors and the negative terminals of the first and second DC systems, or the first resistor and the first resistor. A tenth semiconductor switching device connected between the first and second DC systems and an eleventh semiconductor switching connected between the second resistor and the first terminals of the first and second DC systems And an element.

In another aspect, the first impedance and the second impedance are a fifth reactor and a sixth reactor, and between the fifth and sixth reactors and the negative terminals of the first and second DC systems. , Or a twelfth semiconductor switching element connected between the fifth reactor and the negative terminals of the first and second DC systems, the sixth reactor, and the sixth semiconductor switching element An anode is connected to a common connection point of a thirteenth semiconductor switching element connected between the first terminal and the negative terminal of the second DC system, the fifth reactor and the twelfth semiconductor switching element, and a cathode is the third auxiliary A seventh diode connected to a common connection point of the circuit current switch portion and the positive terminal of the second DC system, the sixth reactor, and the thirteenth semiconductor switch An eighth diode whose anode is connected to a common connection point of the element or the twelfth semiconductor switching element, and whose cathode is connected to a common connection point of the fourth auxiliary circuit current switch portion and the positive terminal of the first DC system; It is characterized by having.

Further, as one aspect thereof, the third auxiliary circuit current switch unit includes an eighth semiconductor switching element having no self arc extinguishing capability, and the fourth auxiliary circuit current switch unit has a self arc extinguishing capability. A ninth semiconductor switching device is provided.

Further, as one aspect thereof, when a current flows from the first DC system to the second DC system and an accident occurs in the second DC system, the fourth auxiliary circuit current switch unit is turned on, After the current flowing to the mechanical circuit breaker becomes lower than a predetermined value, the mechanical circuit breaker is shut off, and current flows from the second DC system to the first DC system, and an accident occurs in the first DC system. When it occurs, the third auxiliary circuit current switch unit is turned on, and the mechanical circuit breaker is shut off after the current flowing through the mechanical circuit breaker becomes less than a predetermined value.

According to the present invention, in the direct current shutoff device, it is possible to shut off bidirectional current more reliably without increasing the capacitance of the capacitor.

FIG. 1 is a circuit diagram showing a direct current cut-off device in a first embodiment. FIG. 2 is a diagram showing a direct current cut-off device in a steady state in the first embodiment. FIG. 2 is a diagram showing a direct current cut-off device at the time of capacitor discharge in Embodiment 1. FIG. 2 is a diagram showing a DC circuit breaker after the first mechanical circuit breaker arc extinguishing in the first embodiment. FIG. 2 is a diagram showing a direct current shutoff device at the time of system reconnection in the first embodiment. 5 is a time chart showing each waveform at the time of second DC system short circuit in the first embodiment. FIG. 7 is a circuit diagram showing a direct current cut-off device in a second embodiment. FIG. 10 is a circuit diagram showing a direct current cut-off device in a third embodiment. The circuit diagram which shows the direct current | flow interruption | blocking apparatus in Embodiment 4. FIG. The figure which shows the direct current | flow interruption apparatus at the time of steady state in Embodiment 4. FIG. The figure which shows the direct current | flow interruption apparatus at the time of capacitor | condenser discharge in Embodiment 4. FIG. The figure which shows the direct current | flow interrupting apparatus after the 1st machine breaker arc extinguishing in Embodiment 4. FIG. The figure which shows the direct current | flow interrupting apparatus at the time of the system reopening in Embodiment 4. FIG. The time chart which shows the current waveform at the time of interception failure in patent documents 1. The circuit diagram which shows the direct current | flow interruption | blocking apparatus in Embodiment 5. FIG. The time chart which shows the operation and current waveform of each part in Embodiment 5. The circuit diagram which shows the direct current | flow interruption | blocking apparatus in Embodiment 6. FIG. The time chart which shows operation of each part in Embodiment 6, and current waveform. The time chart which shows the experimental result in Embodiment 6. FIG. The figure which shows the measurement location of an experimental waveform. The circuit diagram which shows the direct current | flow interrupting apparatus in Embodiment 7. FIG. The time chart which shows operation of each part in an embodiment 7, and current waveform. The figure which shows the structure which connected the direct current | flow interruption | blocking apparatus of Embodiment 5 between-terminal of the 1st, 2nd direct current grid | systems 1 and 2. FIG. The figure which shows the structure which connected the direct current | flow interruption | blocking apparatus of Embodiment 6 between the-terminals of 1st, 2nd direct current grid | systems 1,2. The figure which shows the structure which connected the direct current | flow interruption | blocking apparatus of Embodiment 7 between-terminal of the 1st, 2nd direct current grid | systems 1 and 2. FIG. The circuit diagram which shows the direct current | flow interruption | blocking apparatus in Embodiment 8. FIG. The figure which shows the direct current | flow interruption apparatus in the steady state in Embodiment 8. FIG. The figure which shows the direct current | flow interruption | blocking apparatus when an accident generate | occur | produces in the 2nd direct current | flow system side in Embodiment 8. FIG. The figure which shows the direct current | flow interruption apparatus after the arc interruption | blocking in Embodiment 8. FIG. The figure which shows the direct current | flow interruption | blocking apparatus at the time of restarting the 2nd DC system in Embodiment 8. FIG. The time chart which shows each waveform at the time of short circuit current interruption | blocking of the 2nd DC system in Embodiment 8. FIG. The circuit diagram which shows the direct current | flow interruption | blocking apparatus in Embodiment 9. FIG. The circuit diagram which shows the direct current | flow interruption | blocking apparatus in Embodiment 10. FIG. The circuit diagram which shows the direct current | flow interruption | blocking apparatus in Embodiment 11. FIG. The figure which shows the direct current | flow interruption apparatus at the time of the 12th, 13th semiconductor switching element ON in Embodiment 11. FIG. The figure which shows the direct current | flow interruption | blocking apparatus at the time of the 12th, 13th semiconductor switching element OFF in Embodiment 11. FIG. The figure which shows the direct current | flow interruption | blocking apparatus when an accident generate | occur | produces in the 2nd direct current | flow system side in Embodiment 11. FIG. The figure which shows the direct current | flow interruption | blocking apparatus after arc interruption | blocking in Embodiment 11. FIG. The figure which shows the direct current | flow interruption | blocking apparatus at the time of restarting the 2nd DC system in Embodiment 11. FIG. The figure which shows each waveform of the conventional direct current | flow interruption | blocking apparatus.

Hereinafter, first to eleventh embodiments of the direct current shutoff device in the present invention will be described in detail based on FIGS. 1 to 39.

Embodiment 1
FIG. 1 shows a direct current cut-off device in the first embodiment. As shown in FIG. 1, the DC interrupting device 3 is connected to the first DC system 1 and the second DC system 2. The DC interrupting device 3 includes a first mechanical circuit breaker CB1 and a second mechanical circuit breaker CB2, a capacitor C, a first reactor L1, first and second auxiliary circuit

current switch units

4 and 5, and resistance (impedance). And R.

The first and second auxiliary circuit

current switch units

4 and 5 have first and second semiconductor switching elements T1 and T2. In FIG. 1, thyristors are shown as the first and second semiconductor switching elements T1 and T2, but semiconductor switching elements other than thyristors may be used. Further, diodes may be connected in series to the first and second semiconductor switching elements T1 and T2.

First and second mechanical circuit breakers CB1 and CB2 are connected in series between the + terminal of the first DC system 1 and the + terminal of the second DC system 2.

One end (anode) of the first semiconductor switching element T1 is connected to a common connection point of the + terminal of the first DC system 1 and the first mechanical circuit breaker CB1. One end (cathode) of a second semiconductor switching element T2 is connected to the other end (cathode) of the first semiconductor switching element T1. The other end (anode) of the second semiconductor switching element T2 is connected to the common connection point of the + terminal of the second DC system 2 and the second mechanical circuit breaker CB2.

A capacitor C is connected between a common connection point of the first and second mechanical circuit breakers CB1 and CB2 and a common connection point of the first and second semiconductor switching elements T1 and T2. Further, the first reactor L1 is connected in series to the capacitor C. Here, the connection order of the capacitor C and the first reactor L1 may be either.

Further, a resistance (impedance) R is connected between the common connection point of the first and second semiconductor switching elements T1 and T2 and the negative terminals of the first and second DC systems 1 and 2.

In FIG. 2, the direct current | flow interruption | blocking apparatus 3 in the steady state of this Embodiment 1 is shown. In the steady state, the first mechanical circuit breaker CB1 and the second mechanical circuit breaker CB2 are closed, and current flows in both directions. At this time, the first semiconductor switching device T1 and the second semiconductor switching device T2 are in the off state. In the capacitor C, when the charging current flows through the first reactor L1 and the resistor R and the system voltage is charged, the current flowing to the capacitor C becomes zero. In addition, since current flows in the first mechanical circuit breaker CB1 and the second mechanical circuit breaker CB2 in steady state, there is almost no power loss.

FIG. 3 shows the DC interrupting device 3 when an accident occurs on the second DC system 2 side. By turning on the first semiconductor switching element T1 at the occurrence of an accident on the second DC system 2 side, the discharge current from the capacitor C is used as an auxiliary circuit current: first mechanical circuit breaker CB1 → first semiconductor switching element T1 → first reactor It cancels the short circuit current which flows via L1 and flows from the first DC system 1 to the first mechanical circuit breaker CB1.

At this time, the auxiliary circuit current (discharge current) is a resonant current of a frequency determined by the capacitor C and the first reactor L1. If the resonance frequency is too high, the resonance ends before the first mechanical circuit breaker CB1 opens, and the short circuit current flowing to the first mechanical circuit breaker CB1 returns to the original magnitude. If the resonance frequency is too low, the increase speed of the first mechanical circuit breaker pass current Icb1 due to the short circuit becomes larger than the increase speed of the auxiliary circuit current (discharge current), and the short circuit current can not be canceled. Therefore, it is necessary to set the resonance frequency to be equal to or slightly longer than the operation time of the first mechanical circuit breaker CB1.

When the mechanical circuit breaker passing current becomes smaller than a predetermined value, the first mechanical circuit breaker CB1 is opened. It should be noted that there is a time delay from when the first and second mechanical circuit breakers CB1 and CB2 receive the cutoff designation until they are actually opened. In the present specification, when it is described as blocking or opening, it indicates the time of actual opening.

FIG. 4 shows the DC circuit breaker 3 after arc extinguishing of the first mechanical circuit breaker CB1. After the arc extinguishing, the auxiliary circuit current flows through the first semiconductor switching element T1 → the first reactor L1 → the capacitor C → the second mechanical circuit breaker CB2, and the capacitor C is charged in the opposite direction to the case shown in FIG. Ru.

When the charging of the capacitor C is completed, the current flowing to the second DC system 2 becomes zero, and the current interruption is completed. When the current interruption is completed, the first semiconductor switching element T1 is turned off. When the first semiconductor switching element T1 is a thyristor, the thyristor does not have a self-extinguishing ability, but as shown in FIG. 4, when the charging of the capacitor C is completed, the current flowing through the second DC system 2 becomes zero. , The thyristor can be turned off.

At this time, a current unnecessary for the shutoff flows through the first semiconductor switching element T1 and the resistor R to the minus terminal side of the first and second DC systems 1 and 2 and a loss occurs. Moreover, in order to turn off the first semiconductor switching element (thyristor) T1, it is necessary to make the gate current zero and the forward current smaller than the holding current. Therefore, in order to reduce the loss and to turn off the first semiconductor switching element T1, it is necessary to increase the resistance value of the resistor R so that the current flowing through the resistor R becomes sufficiently small.

FIG. 5 shows the DC interrupting device 3 at the time of system reconnection. At the time of reopening, by closing the first mechanical circuit breaker CB1, current flows from the first DC system 1 side to the second DC system 2 side via the first mechanical circuit breaker CB1 and the second mechanical circuit breaker CB2. In addition, a charging current flows through the first mechanical circuit breaker CB1 → capacitor C → first reactor L1 → resistor R, and the capacitor C, which has been charged in the reverse direction in FIG. 4, is recharged in the original direction. When charging is completed, the state shown in FIG. 2 is reached, and recharging is completed.

The direction of current flow and the current value at the time of an accident occurrence are monitored using the host controller, and the opening and closing of the first and second mechanical circuit breakers CB1 and CB2 and the turning on of the first and second semiconductor switching elements T1 and T2 Do the off.

The waveform at the time of interrupting the short circuit current by the side of the 2nd direct current system 2 in Drawing 6 is shown. At time t1, a short circuit occurs and the first mechanical circuit breaker passing current Icb1 increases. When the first semiconductor switching element T1 is turned on at time t2, a discharge current flows from the capacitor C as the auxiliary circuit current Iaux, and cancels the first mechanical circuit breaker passing current Icb1.

When the first mechanical circuit breaker passing current Icb1 becomes smaller than a predetermined value, the first mechanical circuit breaker CB1 is opened. In FIG. 6, the contact is opened at time t3. At time t3, the first mechanical circuit breaker pass current Icb1 remains, so some arcing occurs, but since the first mechanical circuit breaker pass current Icb1 becomes zero by the auxiliary circuit current Iaux, the arc can be extinguished.

After that, the voltage Vc of the capacitor C is reversely charged by the auxiliary circuit current Iaux and the short circuit current, and when the first system voltage -Vdc of-is exceeded, the charging is completed and the auxiliary circuit current Iaux becomes zero and the interruption is completed.

In the first embodiment, the shutoff method in the case where an accident occurs on the second DC system 2 side is described, but even if an accident occurs on the first DC system 1 side, the same principle and the operation of the target can be used to shut off. It is. In this case, the second mechanical circuit breaker CB2 and the second semiconductor switching element T2 are opened and turned on to extinguish and interrupt the arc of the second mechanical circuit breaker CB2.

As described above, according to the first embodiment, it is possible to shut off the direct current in both directions, and it is possible to shut off the direct current repeatedly by the reopening operation. In addition, it is possible to cut off the current more reliably by creating a zero point in the first mechanical circuit breaker passing current Icb1 by the capacitor discharge current of the auxiliary circuit. Furthermore, since the first and second mechanical circuit breakers CB1 and CB2 are energized at all times during steady state, there is almost no power loss.

In addition, since there is no need to gradually increase the voltage across the open circuit of the first and second mechanical circuit breakers CB1 and CB2, the capacitor capacity of the auxiliary circuit may be small, and the apparatus can be miniaturized. It becomes. In addition, some increase in the parasitic impedance component of the auxiliary circuit can be tolerated.

Second Embodiment
FIG. 7 shows the DC interrupting device 3 of the second embodiment. The direct current cut-off device 3 of the second embodiment is the same as the first embodiment except that an element such as a Zener diode ZD can be added between the resistor R and the negative terminals of the first and second DC systems 1 and 2. It is.

Connecting the Zener diode ZD lowers the voltage across the resistor R. Therefore, according to the direct current cutoff device 3 in the second embodiment, it is possible to reduce the loss due to the unnecessary current at the time of charging the capacitor C.

Third Embodiment
FIG. 8 shows a DC interrupting device 3 of the third embodiment. In the third embodiment, the Zener diode ZD of the second embodiment is replaced with a third semiconductor switching element T3 capable of self-extinguishing to block unnecessary current. The third semiconductor switching element T3 may be a switch other than a self-extinguishing semiconductor switching element.

In the steady state, the third semiconductor switching element T3 is turned on, and the capacitor C is charged as shown in FIG.

When charging of the capacitor C is completed or a shutoff command is received due to a short circuit accident or the like, the third semiconductor switching element T3 is turned off. The completion of charging of the capacitor C is detected on the condition that the voltage across the capacitor C is detected and equal to the grid voltage. Alternatively, the time for completion of charging of capacitor C is calculated in advance from the capacitance value of capacitor C, the resistance value of resistor R, and the inductance value of first reactor L1, and it is determined that charging is completed when the calculated value elapses. You may

After the arc extinguishing, the third semiconductor switching element T3 is off, and unlike in FIG. 4, the unnecessary current flowing through the first semiconductor switching element T1 → the resistor R is blocked by the third semiconductor switching element T3. Therefore, the loss can be reduced.

In addition, since the unnecessary current does not flow even if the resistance value of the resistor R is small, the first semiconductor switching element (thyristor) T1 can be reliably turned off. As a merit of reducing the resistance value of the resistor R, the recharging speed of the capacitor C at the time of reconnection of the system in FIG. 5 is improved. Thus, it is possible to shorten the time taken to complete the blocking preparation.

At the time of reopening, the first mechanical circuit breaker CB1 is closed and the third semiconductor switching element T3 is turned on, whereby the capacitor C is charged as in the first embodiment, and reopening is completed.

As described above, according to the direct current cut-off device 3 of the third embodiment, the same function and effect as those of the first and second embodiments can be obtained. Moreover, the loss which arises in resistance R after electric current interruption can be made into zero.

Fourth Embodiment
The direct current | flow interruption | blocking apparatus 3 of this Embodiment 4 is shown in FIG. The direct current cutoff device 3 of the fourth embodiment is provided with a second reactor (impedance) L2 and a diode D connected in parallel to the second reactor L2 instead of the resistor R of the third embodiment.

FIG. 10 shows the DC interrupting device 3 in the steady state of the fourth embodiment. In the steady state, the first mechanical circuit breaker CB1 and the second mechanical circuit breaker CB2 are closed, and current flows in both directions. In addition, since current flows through the first mechanical circuit breakers CB1 and CB2 in steady state, there is almost no power loss.

At this time, since the first and second semiconductor switching elements T1 and T2 are in the off state, no current flows in the first and second semiconductor switching elements T1 and T2. In addition, the third semiconductor switching element T3 is in the on state, a charging current flows through the capacitor C → the first reactor L1 → the second reactor L2 → the third semiconductor switching element T3, and the capacitor C is charged up to the system voltage. The current flowing in the becomes zero.

When charging is completed, the third semiconductor switching element T3 is turned off. The charge completion is detected on the condition that the voltage across the capacitor C is detected and equal to the system voltage.

Energy stored in the second reactor L2 is consumed by circulating through the second reactor L2 and the diode D after the third semiconductor switching element T3 is turned off.

FIG. 11 shows the DC interrupting device 3 when an accident occurs on the second DC system 2 side. By turning on the first semiconductor switching element T1 at the occurrence of an accident on the second DC system 2 side, the discharge current from the capacitor C is used as an auxiliary circuit current: first mechanical circuit breaker CB1 → first semiconductor switching element T1 → first reactor It cancels the short circuit current which flows via L1 and flows from the first DC system 1 to the first mechanical circuit breaker CB1.

At this time, the auxiliary circuit current (discharge current) is a resonant current of a frequency determined by the capacitor C and the first reactor L1. If the resonance frequency is too high, the resonance ends before the opening of the first mechanical circuit breaker CB1, and the short circuit current flowing to the first mechanical circuit breaker CB1 returns to the original magnitude. If the resonance frequency is too low, the increasing speed of the first mechanical circuit breaker passing current Icb1 due to the short circuit becomes larger than the increasing speed of the auxiliary circuit current, and the short circuit current can not be canceled. Therefore, it is necessary to set the resonance frequency to be equal to or slightly longer than the operation time of the first mechanical circuit breaker CB1.

When the first mechanical circuit breaker passing current becomes smaller than the predetermined value, the first mechanical circuit breaker CB1 is opened. FIG. 12 shows the DC circuit breaker 3 after arc extinguishing of the first mechanical circuit breaker CB1. After arc extinguishing, a short circuit current flows through the first semiconductor switching element T1 → first reactor L1 → capacitor C → second mechanical circuit breaker CB2, and the capacitor C is charged in the opposite direction to that in FIG. When the charging of the capacitor C is completed, the current flowing to the second DC system 2 becomes zero, and the current interruption is completed. When the current interruption is completed, the first semiconductor switching element T1 is turned off.

FIG. 13 shows the DC interrupting device 3 at the time of reconnection of the system. At the time of reopening, by closing the first mechanical circuit breaker CB1, current flows from the first DC system 1 side to the second DC system 2 side via the first mechanical circuit breaker CB1 and the second mechanical circuit breaker CB2.

Further, by turning on the third semiconductor switching element T3, a charging current flows through the first mechanical circuit breaker CB1 → capacitor C → first reactor L1 → second reactor L2 → third semiconductor switching element T3, as shown in FIG. The capacitor C, which was being charged in the reverse direction, is recharged in the original direction.

When charging is completed, the state shown in FIG. 10 is reached, and recharging is completed. In the fourth embodiment, the resistor R is not required by connecting the second reactor L2 and the diode D to the third semiconductor switching element T3.

Therefore, since the capacitor charging current does not flow through the resistor R, the resistance loss at the time of charging is eliminated. Furthermore, while the first semiconductor switching device T1 is on, the third semiconductor switching device T3 is off, and no current flows to the negative terminals of the first and second DC networks 2. Therefore, the first semiconductor switching element T1 which can not be self-extinguished can be reliably turned off. Moreover, since the current is not suppressed by the resistance, the present invention can be applied to a system having a small capacity.

In the fourth embodiment, the current flow direction and the current value at the time of occurrence of an accident are monitored using the host controller, and the opening and closing of the first mechanical circuit breaker CB1 and the on and off of the first and third semiconductor switching elements T1 and T3. I do.

In the fourth embodiment, the shutoff method in the case where an accident occurs on the second DC system 2 side is described, but even when an accident occurs on the first DC system 1 side, the same principle and the operation of the target can be used to shut off. It is. In this case, the second mechanical circuit breaker CB2 and the second semiconductor switching element T2 are opened and turned on to extinguish and interrupt the arc of the second mechanical circuit breaker CB2.

Fifth Embodiment
In the first embodiment, a zero point is created by flowing the auxiliary circuit current Iaux in the reverse direction with respect to the first mechanical circuit breaker passing current Icb1, and the first and second mechanical circuit breakers CB1 and CB2 are opened. The first and second mechanical circuit breakers CB1 and CB2 open at a timing when the mechanical circuit breaker passing current is zero.

In the first mechanical circuit breaker CB1, although an arc may occur once immediately after opening, the arc voltage generated between the contacts of the first mechanical circuit breaker CB1 is not large at that time. Then, the distance between the contacts of the first mechanical circuit breaker CB1 opens and the arc is extinguished, and the contact of the first mechanical circuit breaker CB1 is completely opened in the state of the first mechanical circuit breaker passing current Icb1 = 0 without arc Shut off is complete.

However, if an arc of a certain size is generated once when the first and second mechanical circuit breakers CB1 and CB2 are opened, then the arc can not be extinguished and current flows to the first and second mechanical circuit breakers CB1 and CB2 It may keep flowing and fail to shut off. FIG. 14 shows a current waveform when the interruption fails in the first embodiment. The following factors (1) and (2) can be considered as factors that can not extinguish an arc in the circuit of the first embodiment.

(1) The first and second mechanical circuit breakers CB1 and CB2 have delays and variations between when the opening command is issued and when actually starting the opening. Therefore, a variation also occurs in the first mechanical circuit breaker passing current Icb1 at the timing of time t3 (at the start of opening of the first mechanical circuit breaker CB1) in FIG. When the current slope of the first mechanical circuit breaker passing current Icb1 at time t3 is large, the arc voltage applied between the contacts of the first mechanical circuit breaker CB1 is also large, and it becomes difficult to extinguish the arc.

(2) The first and second mechanical circuit breakers CB1 and CB2 take time until the contact point distance is fully opened after the start of the opening. In addition, the time also varies. If it takes a long time for the contact point distance to fully open after the start of the opening, it is difficult to extinguish the arc.

As a countermeasure, lowering the LC resonance frequency to make the inclination of the current at the start of opening of the first and second mechanical circuit breakers CB1 and CB2 gentler suppresses the arc voltage generated and makes it easy to extinguish the arc. There is a way. However, this leads to an increase in volume, weight, and cost of the first reactor L1 and the capacitor C.

Therefore, in the fifth embodiment, a DC interrupting device capable of solving the above problems will be described. The direct current | flow interruption | blocking apparatus of this Embodiment 5 is shown in FIG. In the fifth embodiment, the third and fourth diodes D3 and D4 are added to the circuit configuration of the first embodiment.

The third diode D3 is connected in parallel to the first mechanical circuit breaker CB1. The anode of the third diode D3 is connected to the common connection point of the first and second mechanical circuit breakers CB1 and CB2, and the cathode is connected to the common connection point of the first semiconductor switching element T1 and the first mechanical circuit breaker CB1. The fourth diode D4 is connected in parallel to the second mechanical circuit breaker CB2. The anode of the fourth diode D4 is connected to the common connection point of the first and second mechanical circuit breakers CB1 and CB2, and the cathode is connected to the common connection point of the second semiconductor switching element T2 and the second mechanical circuit breaker CB2.

The first auxiliary circuit current switch unit 4 of the fifth embodiment is a series connection of the first semiconductor switching element T1 and the first diode D1. The first semiconductor switching element T1 is an element having a self-extinguishing ability, and for example, an IGBT is used. The collector terminal of the first semiconductor switching element T1 is connected to the common connection point of the + terminal of the first DC system 1 and the first mechanical circuit breaker CB1. The anode terminal of the first diode D1 is connected to the emitter terminal side of the first semiconductor switching element T1. The cathode terminal of the first diode D1 is connected to the common connection point of the first reactor L1 and the resistor R. The connection order of the first semiconductor switching element T1 and the first diode D1 may be reversed.

In addition, the second auxiliary circuit current switch unit 5 connects the second semiconductor switching element T2 and the second diode D2 in series. The second semiconductor switching element T2 is an element having a self-extinguishing ability, and for example, an IGBT is used. The collector terminal of the second semiconductor switching element T2 is connected to the common connection point of the + terminal of the second DC system 2 and the second mechanical circuit breaker CB2. The anode terminal of the second diode D2 is connected to the emitter terminal side of the second semiconductor switching element T2. The cathode terminal of the second diode D2 is connected to the common connection point of the first reactor L1 and the resistor R. The connection order of the second semiconductor switching element T2 and the second diode D2 may be reversed.

The first and second auxiliary circuit

current switches

4 and 5 may be thyristors as in the first embodiment.

The operation and operation of the fifth embodiment are as follows. The difference from the first embodiment will be described. The operation of the DC interrupting device of the fifth embodiment and the current flowing to each part are summarized in FIG.

The operation is the same as in the first embodiment. After opening the first mechanical circuit breaker CB1, when the first semiconductor switching element T1 is turned on, the auxiliary circuit current Iaux flows in the opposite direction to the short circuit current to cancel the short circuit current.

Since the auxiliary circuit current Iaux is a sine wave and its amplitude is designed to be larger than the short circuit current, the excess current after canceling the short circuit current has a negative value. Therefore, excess negative current flows through the third diode D3 connected in parallel to the first mechanical circuit breaker CB1. When the auxiliary circuit current Iaux becomes smaller, a short circuit current flows through the first semiconductor switching element T1 → the first diode D1 → the first reactor L1 → the capacitor C, and the capacitor C is charged in the reverse direction. When the charging of the capacitor C is completed, the current flowing through the second DC system 2 becomes zero and the disconnection is completed.

As described above, there is a time delay from the reception of the opening command of the first mechanical circuit breaker CB1 to the actual opening of the first mechanical circuit breaker CB1. Due to this time delay, the opening start of the first mechanical circuit breaker CB1 is delayed after the first semiconductor switching element T1 is turned on, and the first zero point of the combined current of the short circuit current and the auxiliary circuit current Iaux (point A in FIG. 16) Even when it is later than the first zero point A, a second zero point of the combined current of the short circuit current and the auxiliary circuit current I aux (see FIG. 16) is the opening start of the first mechanical circuit breaker CB1. Point B of: If it can be performed earlier than the second zero point B), the combined current of the short circuit current and the auxiliary circuit current Iaux is immediately (approximately 100 μs) diverted to the third diode D3. Therefore, no arc occurs. The subsequent operation is the same as that of the first embodiment.

In the fifth embodiment, the excess auxiliary circuit current Iaux can be bypassed to the third diode D3 connected in parallel to the first mechanical circuit breaker CB1. After the first zero point A after the opening of the first mechanical circuit breaker CB1, the current is commutated to the third diode D3. Since the applied contact voltage is only the voltage drop of the third diode D3 lower than the arc voltage, during the conduction of the third diode D3 (that is, during the period from the first zero point A to the second zero point B in FIG. 16) Arc does not occur. That is, it is desirable to open the first mechanical circuit breaker CB1 in a period from the first zero point A to the second zero point B (auxiliary circuit current Iaux> short circuit current).

At the second zero point B, the contact distance of the first mechanical circuit breaker CB1 is extended, and no arc is generated between the first zero point A and the second zero point B, so the gas temperature between the contacts drops and it is difficult to cause dielectric breakdown. Therefore, even if a voltage is applied between the contacts of the first mechanical circuit breaker CB1 after the second zero point B of FIG. 16, there is almost no possibility that an arc will occur.

Therefore, since the inclination of the large current at the first zero point A, which is the problem of (1), can be tolerated, the LC resonance frequency can be increased. This leads to the downsizing of the first reactor L1 and the capacitor C, and further to the downsizing and cost reduction of the DC interrupting device.

In addition, since the amplitude of the excess auxiliary circuit current Iaux can be tolerated, interruption of a short circuit current smaller than expected (a short circuit current smaller than the amplitude of the auxiliary circuit current Iaux) can be coped with.

As described above, according to the fifth embodiment, when the contact openings of the first and second mechanical circuit breakers CB1 and CB2 do not meet the first zero point A, the first and second mechanical circuit breakers CB1 and CB2 By the operation of the third and fourth diodes D3 and D4 connected in parallel to each other, generation of arc can be suppressed. Thereby, as compared with the first embodiment, it is possible to increase the probability that the short circuit current can be cut off.

Since the arc causes steady loss increase due to contact wear and interruption failure due to contact adhesion, it is possible to reduce the time for replacement and maintenance of the first and second mechanical circuit breakers CB1 and CB2 by reducing the arc.

Further, since the arc causes the temperature rise between the contacts and the dielectric breakdown, the fifth embodiment which reduces the arc can perform more reliable interruption. Thus, the reliability of the device can be improved.

Sixth Embodiment
In the fifth embodiment, when the LC resonance frequency is designed large and opened at the first zero point A of the combined current of the short circuit current and the auxiliary circuit current Iaux, the time between the first zero point A and the second zero point B becomes short. Even at the second zero point B, the distance between the contacts is insufficient. In addition, the decrease in gas temperature between the contacts becomes insufficient. As a result, breakdown occurs during opening, leaving the risk of arcing again.

Furthermore, in the case where the opening of the first mechanical circuit breaker CB1 comes before the first zero point A of the combined current of the short circuit current and the auxiliary circuit current Iaux, an arc may be generated and the arc can not be extinguished as in the first embodiment. There is.

Therefore, in the fifth embodiment, it is not easy to design the delay time from the detection of the LC resonance frequency or the short circuit accident to the opening command of the first and second mechanical circuit breakers CB1 and CB2.

The direct current | flow interruption | blocking apparatus of this Embodiment 6 is shown in FIG. The sixth embodiment is a circuit configuration in which fourth and fifth semiconductor switching elements (for example, IGBTs) T4 and T5 having self-extinguishing ability are provided instead of the third and fourth diodes D3 and D4 of the fifth embodiment. It is. That is, the fourth semiconductor switching element T4 is connected in parallel to the first mechanical circuit breaker CB1. The emitter terminal of the fourth semiconductor switching element T4 is connected to the common connection point of the first and second mechanical circuit breakers CB1 and CB2, and the collector terminal is at the common connection point of the first semiconductor switching element T1 and the first mechanical circuit breaker CB1. Connected The fifth semiconductor switching element T5 is connected in parallel to the second mechanical circuit breaker CB2. The emitter terminal of the fifth semiconductor switching element T5 is connected to the common connection point of the first and second mechanical circuit breakers CB1 and CB2, and the collector terminal is at the common connection point of the second semiconductor switching element T2 and the second mechanical circuit breaker CB2. Connected

A semiconductor switch in which diodes are connected in antiparallel as shown in FIG. 17 is applied to the fourth and fifth semiconductor switching elements T4 and T5. The first and second auxiliary circuit

current switches

4 and 5 may be thyristors as in the first embodiment.

Hereinafter, the difference from the first embodiment will be described with respect to the operation and action of the sixth embodiment. The operation of the DC interrupting device in the sixth embodiment and the current flowing to each portion are summarized in FIG.

In the steady state, the fourth and fifth semiconductor switching elements T4 and T5 are turned off by the gate command, and the operation is the same as in the first embodiment. In the operation when the shutoff command comes due to a short circuit accident etc., the fourth semiconductor switching element T4 is turned on by the gate command before the opening command of the first machine breaker CB1 (when the second machine breaker CB2 is opened) Turns on the fifth semiconductor switching element T5).

After that, the first mechanical circuit breaker CB1 is opened by the opening command of the first mechanical circuit breaker CB1. When the first mechanical circuit breaker CB1 is turned on, even if the fourth semiconductor switching element T4 is turned on, the current does not divert to the fourth semiconductor switching element T4 because there is an on resistance component of the semiconductor switching element. Therefore, there is no problem even if the fourth semiconductor switching element T4 is always on in the steady state.

When opening of the first mechanical circuit breaker CB1 is started in a state where the fourth semiconductor switching element T4 is on, an arc voltage is applied between the contacts of the first mechanical circuit breaker CB1. When the voltage exceeds the on voltage of the fourth semiconductor switching device T4 (the voltage between the collector and the emitter during the gate command on of the fourth semiconductor switching device T4), the current is diverted to the fourth semiconductor switching device T4.

When the current is completely commutated, the arc of the first mechanical circuit breaker CB1 is extinguished. When the commutation to the fourth semiconductor switching element T4 is completed, the discharge current from the capacitor C (auxiliary circuit current Iaux) is switched from the fourth semiconductor switching element T4 to the fourth by turning on the first semiconductor switching element T1 according to the gate command. 1) The semiconductor switching element T1 → the first diode D1 → the first reactor L1 flows, and the short circuit current (current I _T4 ) flowing from the first DC system 1 to the fourth semiconductor switching element T4 is cancelled.

The fourth semiconductor switching element T4 is turned off by the gate command at the timing when the auxiliary circuit current Iaux peaks. This is after a lapse of 1⁄4 of the LC resonance period from the turning on of the first semiconductor switching element T1. Therefore, it is not necessary to detect the passing current or the auxiliary circuit current Iaux during the off operation of the fourth semiconductor switching element T4.

After opening the first mechanical circuit breaker CB1, a short circuit current flows through the first semiconductor switching element T1 → the first diode D1 → the first reactor L1 → the capacitor C, and the capacitor C is charged to the reverse polarity. When the charging of the capacitor C is completed, the current flowing to the second DC system 2 becomes zero, and the current interruption is completed. After that, the first semiconductor switching element T1 is turned off by the gate command. The operation after the current cutoff is the same as in the first embodiment.

In the sixth embodiment, since the short circuit current is diverted to the fourth semiconductor switching element T4 (about 100 μs) immediately after the first mechanical circuit breaker CB1 is opened, an arc hardly occurs. Therefore, the opening command of the first mechanical circuit breaker CB1 can be issued earlier (immediately after the fourth semiconductor switching element T4 ON command), and there is no need to worry about the points to be noted in the fifth embodiment described above. The shutoff operation can be performed. Furthermore, the amplitude of the LC resonant frequency and the auxiliary circuit current Iaux can be designed to be higher than those of the fifth embodiment.

Further, since anti-parallel diodes are connected in the fourth and fifth semiconductor switching elements T4 and T5, the same effect as in the fifth embodiment is obtained, and the opening start time of the first mechanical circuit breaker CB1 is the first Even if it is delayed between the zero point A and the second zero point B, arcs hardly occur.

Furthermore, the turn-off of the fourth semiconductor switching element T4 is fixed after 1⁄4 of the LC resonance period has elapsed since the first semiconductor switching element T1 is turned on. Therefore, if the relationship of “short circuit current <auxiliary circuit current Iaux” is established, the current at the time of turn-off of the fourth semiconductor switching device T4 passes through the anti-parallel diode in the fourth semiconductor switching device T4.

Therefore, zero current switching is established in the fourth semiconductor switching element T4. Therefore, in the fourth semiconductor switching element T4, no switching loss occurs at turn-off, so the thermal duty is small, and at turn-off, a surge voltage between the collector and the emitter of the fourth semiconductor switching element T4 hardly occurs.

Therefore, when interrupting a large current, the number of IGBTs in series and parallel connection for the fourth semiconductor switching element T4 can be reduced, and a snubber circuit for surge voltage suppression is also unnecessary.

Further, even in the case of “short circuit current> auxiliary circuit current Iaux”, in the sixth embodiment, the short circuit current can be interrupted by the fourth semiconductor switching element T4. Also in this case, the fourth semiconductor switching element T4 is turned off at a timing after 1⁄4 of the LC resonance period since the turning on of the first semiconductor switching element T1 (that is, the timing at which the current of the fourth semiconductor switching element T4 is minimized). Therefore, switching loss and surge voltage can be minimized.

The waveform at the time of performing the interruption | blocking experiment of the direct current of 1 kA with the direct current | flow interrupting apparatus of this Embodiment 6 is shown in FIG. FIG. 20 shows the waveform measurement points of FIG.

The experimental conditions are: The setting time from the opening command of the first mechanical circuit breaker CB1 to the gate command of the first semiconductor switching element T1 is approximately 3. It was 6 ms. In addition, at time 0 ms, a cutoff current (1 kA) is already supplied to the first mechanical circuit breaker CB1, and at time 0.5 ms, the gate on command of the fourth semiconductor switching element T4 and the opening command of the first mechanical circuit breaker CB1 are approximately simultaneously. I input it. Also, under this experimental condition, the opening operation of the first mechanical circuit breaker CB1 is started with almost no delay after the opening command of the first mechanical circuit breaker CB1.

At time 0.5 ms immediately after the start of opening of the first mechanical circuit breaker CB1, 13 V is applied to both ends of the first mechanical circuit breaker CB1, so it can be seen that an arc is generated. However, the arc voltage 13V at this time is much lower than the maximum arc voltage 30V of the first mechanical circuit breaker CB1.

That is, it is a voltage level in which arc extinguishing is easy. Immediately after that, since the current i _T4 flowing through the fourth semiconductor switching element T4 matches the cutoff current 1 kA, the first mechanical circuit breaker passing current Icb1 is zero. Furthermore, since the waveform of the voltage Vcb1 across the first mechanical circuit breaker is also reduced to approximately 0 V, it can be confirmed that the arc is also extinguished.

(In the first embodiment and the fifth embodiment, since there is no fourth semiconductor switching element T4 of the circuit for commutation, an arc continues to occur for 3.6 ms up to the first zero point A.)
Also, after the first semiconductor switching element T1 is turned on, the short circuit current flowing to the fourth semiconductor switching element T4 is canceled by the auxiliary circuit current Iaux, and the current i _T4 passing through the fourth semiconductor switching element _T4 is reversed. At the time when the current flows to the antiparallel diode in the semiconductor switching element T4, the fourth semiconductor switching element T4 is turned off by the gate command.

After the second zero point B of the fourth semiconductor switching device T4, a voltage exceeding the maximum arc voltage of 30 V is applied to the first mechanical circuit breaker CB1. Therefore, it can be confirmed that the opening operation of the first mechanical circuit breaker CB1 is completed without the occurrence of an arc in the first mechanical circuit breaker CB1, and it can be understood that the interruption operation has been performed normally.

Patent Document 2 is a similar prior art to Embodiment 6. However, Patent Document 2 is an invention of a unidirectional current breaker and does not correspond to a bidirectional current breaker. In addition, a separate charging circuit is required for the resonant capacitor.

Further, in the eighth embodiment of Patent Document 2, according to paragraph [0038], the turn-off timing of the semiconductor switch is when the contact distance of the disconnecting device 3 is sufficiently long. The current passing through the semiconductor switch at this timing is unknown, and a large short circuit current may have to be interrupted by the semiconductor switch. In this case, a very large switching loss and surge voltage may occur to damage the device. If multiple semiconductor switching elements are connected in parallel or a large capacity snubber circuit is connected to prevent this, the cost and volume of the device will increase. On the other hand, in the sixth embodiment, since zero current switching is established, the number of parallel semiconductor switching elements can be reduced, and the cost and volume of the device can be reduced.

As described above, according to the sixth embodiment, in addition to the effect of the fifth embodiment, when the first and second mechanical circuit breakers CB1 and CB2 are opened, the short-circuit current is rapidly reduced to the fourth and fifth Since the current is commutated to the semiconductor switching elements T4 and T5, the arc can be further suppressed. Thus, the reliability of the device is further enhanced.

In addition, the first and second mechanical circuit breakers CB1 and CB2 can be opened earlier with respect to the first zero point A, and the characteristics of the first and second mechanical circuit breakers CB1 and CB2 (from the opening command to the opening) Even when there is a variation in the delay time until the start of operation, etc., the current can be cut off reliably.

Further, since the design margin of the LC resonance circuit is expanded compared to the fifth embodiment, it is possible to increase the LC resonance frequency, and hence to miniaturize the first reactor L1 and the capacitor C. Therefore, it is possible to miniaturize the direct current shutoff device.

Further, the sixth embodiment produces the following effects with respect to the seventh embodiment described later. Even if the short circuit current is larger than the auxiliary circuit current Iaux, the current can be cut off. Even in this case, switching loss and surge occur but are minimized, so the duty of the fourth and fifth semiconductor switching elements T4 and T5 can be suppressed.

Seventh Embodiment
The direct current | flow interruption | blocking apparatus of this Embodiment 7 is shown in FIG. In the seventh embodiment, the sixth and seventh semiconductor switching elements T6 and T7 (for example, thyristors) having no self-extinguishing ability are connected in antiparallel to the third and fourth diodes D3 and D4 of the fifth embodiment. . The cathode terminal of the sixth semiconductor switching element T6 is connected to the common connection point of the first and second mechanical circuit breakers CB1 and CB2, and the anode terminal is connected to the common connection point of the first semiconductor switching element T1 and the first mechanical circuit breaker CB1. Connected Similarly, the cathode terminal of the seventh semiconductor switching element T7 is connected to the common connection point of the first and second mechanical circuit breakers CB1 and CB2, and the anode terminal is common to the second semiconductor switching element T2 and the second mechanical circuit breaker CB2. Connected to connection point.

Further, in the seventh embodiment, the first and second auxiliary circuit

current switch portions

4 and 5 are the first and second semiconductor switching elements T1 and T2 (for example, thyristors) having no self-extinguishing ability. The IGBT and the diode may be connected in series similarly to the fifth and sixth embodiments.

The operation and operation of the seventh embodiment are as follows. The difference from Embodiment 6 is described. The operation of the direct current cut-off device in the seventh embodiment and the current flowing to each portion are summarized in FIG.

When the shutoff command is received due to a short circuit accident or the like, an ON command is output to the sixth semiconductor switching element T6. After opening the first mechanical circuit breaker CB1, an arc voltage is applied to the first mechanical circuit breaker CB1. When the voltage exceeds the on voltage of the sixth semiconductor switching element T6, current is diverted to the sixth semiconductor switching element T6.

When the current of the first mechanical circuit breaker CB1 is completely diverted to the sixth semiconductor switching device T6, the arc of the first mechanical circuit breaker CB1 is extinguished. When the commutation to the sixth semiconductor switching element T6 is completed, the discharge current (auxiliary circuit current Iaux) component from the capacitor C is switched to the sixth semiconductor switching element T6 by turning on the first semiconductor switching element T1 according to the gate command. It cancels the short circuit current which flows via the first semiconductor switching element T1 → the first reactor L1 and flows from the first DC system 1 to the sixth semiconductor switching element T6. If an off command is previously input to the sixth semiconductor switching element T6, the sixth semiconductor switching element T6 is turned off when the current flowing through the sixth semiconductor switching element T6 becomes zero. Therefore, immediately after the first mechanical circuit breaker CB1 is opened, an off command of the sixth semiconductor switching element T6 is output.

There is variation in the time from when the opening command is issued to the first mechanical circuit breaker CB1 to when the opening is actually started. In order to prevent the sixth semiconductor switching device T6 from turning off before the first mechanical circuit breaker CB1 opens, the off command of the sixth semiconductor switching device T6 takes into account the variation, for example, the opening of the first mechanical circuit breaker CB1 Set to 1 to 2 ms after command.

In general, thyristors have components corresponding to high withstand voltage and large current compared to IGBTs. There are also devices that can flow 10 times the rated current in a short time (10 ms). The thyristor has an advantage that the on-voltage is lower than that of the IGBT, and commutation is easy at the time of opening of the first and second mechanical circuit breakers CB1 and CB2.

In the seventh embodiment, when the short circuit current is larger than the auxiliary circuit current Iaux, the current of the sixth semiconductor switching device T6 can not be reduced to 0 A or less, and thus the sixth semiconductor switching device T6 can not be turned off. That is, the short circuit current can not be cut off. Therefore, care must be taken in the design of the LC resonant circuit to prevent such operation.

As described above, according to the seventh embodiment, the same function and effect as those of the fifth and sixth embodiments can be obtained. Further, according to the seventh embodiment, the following effects are obtained with respect to the sixth embodiment.

Unlike the sixth embodiment, the timing of the gate-off command of the sixth and seventh semiconductor switching elements T6 and T7 (thyristor) connected in parallel to the first and second mechanical circuit breakers CB1 and CB2 is set to 1/4 of the LC resonance period. There is no need to Therefore, the design of the gate command becomes easy.

Since there is a part corresponding to high withstand voltage and large current compared with IGBT if it is a thyristor, application of the device to a high voltage and large capacity system becomes easy. In addition, since the thyristor has a lower on-voltage compared to the IGBT, the voltage drop does not increase even if a plurality of series are connected, so the mechanical circuit breaker passing current is easily commutated to the thyristor and can be applied to a higher voltage system. .

Further, the seventh embodiment produces the following effects with respect to the patent document 2. It is possible to shut off the current flowing in both directions. No external power supply is required for the capacitor of the resonant circuit. Since no switching loss occurs in the added sixth and seventh semiconductor switching elements T6 and T7, the thermal duty of the sixth and seventh semiconductor switching elements T6 and T7 is small, and the number of series and parallel connections can be reduced. A large capacity snubber circuit is also unnecessary. Therefore, cost and volume can be reduced.

In the first to seventh embodiments, the configuration in which the first and second mechanical circuit breakers CB1 and CB2 are connected in series between the + terminal of the first DC system 1 and the + terminal of the second DC system 2 has been described. The first and second mechanical circuit breakers CB1 and CB2 may be connected in series between the − terminal of the first DC system 1 and the − terminal of the second DC system 2.

In this case, one end (cathode) of the first semiconductor switching element T1 is connected to the common connection point of the negative terminal of the first DC system 1 and the first mechanical circuit breaker CB1. One end (anode) of the second semiconductor switching element T2 is connected to the other end (anode) of the first semiconductor switching element T1. The other end (cathode) of the second semiconductor switching element T2 is connected to the common connection point of the − terminal of the second DC system 2 and the second mechanical circuit breaker CB2.

Furthermore, the resistor R of the first embodiment, the Zener diode ZD of the second embodiment, and the third semiconductor switching element T3 of the third and fourth embodiments are connected to the positive terminals of the first and second DC systems 1 and 2.

Also in the second to seventh embodiments, in the case of connecting a DC interrupting device between the − terminal of the first DC system 1 and the − terminal of the second DC system 2, the connection may be made in the same manner as the first embodiment.

A configuration in which the DC interrupting device of the fifth embodiment is connected between the − terminal of the first DC system 1 and the − terminal of the second DC system 2 is shown in FIG. As shown in FIG. 23, a first mechanical circuit breaker CB1 and a second mechanical circuit breaker CB2 are connected in series between the − terminal of the first DC system 1 and the − terminal of the second DC system 2.

The emitter terminal of the first semiconductor switching element T1 is connected to the common connection point of the − terminal of the first DC system 1 and the first mechanical circuit breaker CB1. The cathode terminal of the first diode D1 is connected to the collector terminal of the first semiconductor switching element T1. Here, the connection order of the first semiconductor switching element T1 and the first diode D1 may be reversed.

The emitter terminal of the second semiconductor switching element T2 is connected to the common connection point of the − terminal of the second DC system 2 and the second mechanical circuit breaker CB2. The cathode terminal of the second diode D2 is connected to the collector terminal of the second semiconductor switching element T2. The anode terminal of the second diode D2 is connected to the anode terminal of the first diode D1. Here, the connection order of the second semiconductor switching element T2 and the second diode D2 may be reversed.

A capacitor C is connected between the common connection point of the first and second mechanical circuit breakers CB1 and CB2 and the common connection point of the first and second diodes D1 and D2. The first reactor L1 is connected in series to the capacitor C. Here, the connection order of the capacitor C and the first reactor L1 may be reversed. A resistor R is connected between the common connection point of the first and second diodes D1 and D2 and the positive terminals of the first and second DC systems 1 and 2.

A third diode D3 is connected in parallel to the first mechanical circuit breaker CB1. The anode terminal of the third diode D3 is connected to the common connection point of the-terminal of the first DC system 1 and the first mechanical circuit breaker CB1. The cathode terminal of the third diode D3 is connected to the common connection point of the first and second mechanical circuit breakers CB1 and CB2. The fourth diode D4 is connected in parallel to the second mechanical circuit breaker CB2. The anode terminal of the fourth diode D4 is connected to the common connection point of the-terminal of the second DC system 2 and the second mechanical circuit breaker CB2. The cathode terminal of the fourth diode D4 is connected to the common connection point of the first and second mechanical circuit breakers CB1 and CB2.

A configuration in which the DC interrupting device of the sixth embodiment is connected between the − terminal of the first DC system 1 and the − terminal of the second DC system 2 is shown in FIG. In FIG. 24, the third and fourth diodes D3 and D4 in FIG. 23 are replaced with fourth and fifth semiconductor switching elements (IGBTs) T4 and T5. The emitter terminal of the fourth semiconductor switching element T4 is connected to the common connection point of the first terminal of the first DC system 1 and the first mechanical circuit breaker CB1. The collector terminal of the fourth semiconductor switching element T4 is connected to the common connection point of the first and second mechanical circuit breakers CB1 and CB2. The emitter terminal of the fifth semiconductor switching element T5 is connected to the common connection point of the − terminal of the second DC system 2 and the second mechanical circuit breaker CB2. The collector terminal of the fifth semiconductor switching element T5 is connected to the common connection point of the first and second mechanical circuit breakers CB1 and CB2.

A configuration in which the DC interrupting device of the seventh embodiment is connected between the − terminal of the first DC system 1 and the − terminal of the second DC system 2 is shown in FIG. In FIG. 25, sixth and seventh semiconductor switching elements (thyristors) T6 and T7 are connected in antiparallel to the third and fourth diodes D3 and D4 in FIG.

The cathode terminal of the sixth semiconductor switching element T6 is connected to the common connection point of the − terminal of the first DC system 1 and the first mechanical circuit breaker CB1. The anode terminal of the sixth semiconductor switching element T6 is connected to the common connection point of the first and second mechanical circuit breakers CB1 and CB2. The cathode terminal of the seventh semiconductor switching element T7 is connected to the common connection point of the − terminal of the second DC system 2 and the second mechanical circuit breaker CB2. The anode terminal of the seventh semiconductor switching element T7 is connected to the common connection point of the first and second mechanical circuit breakers CB1 and CB2.

[Eighth embodiment]
FIG. 26 shows a main circuit configuration of the eighth embodiment. As shown in FIG. 26, the DC circuit breaker 3 according to the eighth embodiment includes a mechanical circuit breaker CB, third and fourth auxiliary circuit

current switch parts

6 and 7, and first and second capacitors C1 and C2. The third and fourth reactors L3 and L4 and the first and second resistors R1 and R2 are provided. Here, the third auxiliary circuit current switch unit 6 is a series connection of an eighth semiconductor switching device T8 and a fifth diode D5, and the fourth auxiliary circuit current switch unit 7 is a ninth semiconductor switching device T9 and a sixth diode D6. Series connection.

A mechanical circuit breaker CB is connected between the + terminal of the first DC system 1 and the + terminal of the second DC system 2.

A first capacitor C1, a third reactor L3, and a first between the positive terminal of the first DC system 1 and the common connection point of the mechanical circuit breaker CB and the negative terminals of the first and second DC systems 1 and 2. A resistor (first impedance) R1 is sequentially connected in series. (The order of connection of the first capacitor C1 and the third reactor L3 may be reversed.) One end of an eighth semiconductor switching element T8 at the common connection point of the machine breaker CB and the + terminal of the second DC system 2 Is connected. The anode of the fifth diode D5 is connected to the other end of the eighth semiconductor switching element T8. The cathode of the fifth diode D5 is connected to the common connection point of the third reactor L3 and the first resistor R1.

A second capacitor C2, a fourth reactor L4, and a second resistor are connected between the + terminal of the second DC system 2 and the common connection point of the mechanical circuit breaker CB and the − terminals of the first and second DC systems 1 and 2. The (second impedance) R2 is sequentially connected in series. (The order of connection of the second capacitor C2 and the fourth reactor L4 may be reversed.) One end of a ninth semiconductor switching element T9 at the common connection point of the machine breaker CB and the + terminal of the first DC system 1 Is connected. The other end of the ninth semiconductor switching element T9 is connected to the anode of a sixth diode D6. The cathode of the sixth diode D6 is connected to the common connection point of the fourth reactor L4 and the second resistor R2.

The eighth and ninth semiconductor switching elements T8 and T9 of the eighth embodiment are switching elements capable of self-extinguishing. 26, the collector terminal of the eighth semiconductor switching element T8 is connected to the common connection point between the + terminal of the second DC system 2 and the mechanical circuit breaker CB. Further, the collector terminal of the ninth semiconductor switching element T9 is connected to the common connection point of the + terminal of the first DC system 1 and the mechanical circuit breaker CB. The emitter terminals of the eighth and ninth semiconductor switching elements T8 and T9 are connected to the anodes of the fifth and sixth diodes D5 and D6.

The eighth and ninth semiconductor switching elements T8 and T9 and the fifth and sixth diodes D5 and D6 may be replaced by switching elements such as reverse blocking IGBTs having a reverse blocking capability and capable of self-ignition.

Next, the operation of the direct current cut-off device in the first embodiment will be described.

FIG. 27 shows the DC interrupting device in the steady state of the eighth embodiment. In the steady state, the mechanical circuit breaker CB is closed, and current flows in both directions. At this time, a charging current flows through the first capacitor C1 via the third reactor L3 and the first resistor R1. In addition, a charging current flows through the second capacitor C2 via the fourth reactor L4 and the second resistor R2.

When the first and second capacitors C1 and C2 are charged to the grid voltage, the charging current becomes zero. Since the current passes only through the mechanical circuit breaker CB under constant conditions, there is almost no power loss.

The direct current | flow interruption | blocking apparatus 3 of this Embodiment 8 in case an accident generate | occur | produces in FIG. 28 at the 2nd direct current | flow system 2 side is shown. When an accident occurs, the ninth semiconductor switching element T9 is turned ON, and the discharge current from the second capacitor C2 passes through the mechanical circuit breaker CB → the ninth semiconductor switching element T9 → the sixth diode D6 → the fourth reactor L4 as the auxiliary circuit current. Flow. The auxiliary circuit current cancels the short circuit current flowing through the mechanical circuit breaker CB to create a current zero, and opens the mechanical circuit breaker CB to extinguish the arc.

The magnitude of the auxiliary circuit current is determined by the fourth reactor L4 and the second capacitor C2. Therefore, the magnitude | sizes of 4th reactor L4 and 2nd capacitor | condenser C2 are determined so that the maximum value of the short circuit current assumed may be negated.

The direct current | flow interruption | blocking apparatus 3 of this Embodiment 8 after arc extinguishing is shown in FIG. The auxiliary circuit current flows via the ninth semiconductor switching element T9 → sixth diode D6 → the fourth reactor L4 → the second capacitor C2, and charges the second capacitor C2 in the opposite direction to that shown in FIG. When the charging of the second capacitor C2 is completed, the current on the second DC system 2 side becomes zero, and the interruption of the current is completed.

At this time, a current unnecessary for the blocking operation flows through the ninth semiconductor switching element T9 → the sixth diode D6 → the second resistor R2 to generate a loss. It is necessary to increase the resistance value of the second resistor R2 so that the current is sufficiently reduced. The same applies to the first resistor R1. When reverse charging of the second capacitor C2 is completed and interruption of current is completed, the ninth semiconductor switching element T9 is turned off.

FIG. 30 shows the DC interrupting device 3 of the eighth embodiment when the current interrupting is completed and the second DC system 2 is turned on again. When the mechanical circuit breaker CB is closed, current flows through the mechanical circuit breaker CB → second capacitor C 2 → fourth reactor L 4 → second resistor R 2, and the second capacitor C 2, which has been charged in the opposite direction, Recharge in the direction. When the charging is completed, the state returns to the state of FIG.

The direction of current flow and the current value at the time of the occurrence of an accident are monitored using the upper controller, and the opening and closing of the machine breaker CB and the ON and OFF of the eighth and ninth semiconductor switching elements T8 and T9 are performed.

The waveform at the time of interrupting the short circuit current by the side of the 2nd direct current system 2 in Drawing 31 is shown. A short circuit occurs at time t1, and the mechanical circuit breaker passing current Icb increases. When the ninth semiconductor switching element T9 is turned on at time t2, a discharge current flows from the second capacitor C2 as the auxiliary circuit current Iaux, and the mechanical circuit breaker passing current Icb is cancelled.

At this time, the auxiliary circuit current Iaux is a resonant current of a frequency determined by the second capacitor C2 and the fourth reactor L4. If the resonance frequency is too high, the resonance ends and the mechanical circuit breaker passing current Icb returns to the original size before opening the mechanical circuit breaker CB. Also, if the resonance frequency is too low, the increase rate of the mechanical circuit breaker pass current Icb due to a short circuit becomes larger than the auxiliary circuit current Iaux increase speed, and a zero point can not be formed in the mechanical circuit breaker pass current Icb. Therefore, it is necessary to set the resonance frequency to be equal to or slightly longer than the mechanical circuit breaker CB operation time.

When the mechanical circuit breaker passing current Icb decreases to some extent, the mechanical circuit breaker CB is opened. The following two can be considered about the determination method of the timing which opens mechanical breaker CB. The first method is a method of detecting the mechanical circuit breaker passing current Icb with a current sensor and opening the detected value when the detected value is less than the allowable value. The second method is a method of calculating the time at which the auxiliary circuit current Iaux is maximum from the values of the fourth reactor L4 and the second capacitor C2 and opening the mechanical circuit breaker CB at that timing.

It should be noted that there is a time delay from when the mechanical circuit breaker CB receives the interruption designation until it is actually opened. In the case where it is stated in the present specification that interruption is to be made, it shall indicate the time of actual opening.

In FIG. 31, the mechanical circuit breaker CB is opened at time t3. Although the mechanical circuit breaker pass current Icb remains at time t3, some arcing occurs, but the mechanical circuit pass current Icb becomes zero thereafter by the auxiliary circuit current Iaux, so that the arc can be extinguished.

Thereafter, the voltage Vc2 of the second capacitor C2 is reversely charged by the resonance current and the short circuit current, and when the negative system voltage Vdc is reached, the charging is completed, the auxiliary circuit current Iaux becomes zero, and the interruption is completed.

In the eighth embodiment, the shutoff method in the case where an accident occurs on the second DC system 2 side is described, but it is possible to shut off similarly in the case where an accident occurs on the first DC system 1 side. In this case, turning on the eighth semiconductor switching element T8 instead of the ninth semiconductor switching element T9 cancels the short circuit current passing through the mechanical circuit breaker CB using the discharge current of the first capacitor C1.

As described above, according to the eighth embodiment, it is possible to form a zero point in the machine circuit breaker passing current Icb by the capacitor discharge current of the auxiliary circuit, and to cut off bidirectional DC current with certainty.

Furthermore, since the mechanical circuit breaker CB is always energized during steady state, there is almost no power loss. Since the eighth and ninth semiconductor switching elements T8 and T9 increase with an inclination from the zero current by the third and fourth reactors L3 and L4 immediately after ON (see Iaux in FIG. 31B), the turn is ON The losses are very small. Further, the eighth and ninth semiconductor switching elements T8 and T9 do not interrupt the short circuit current, and turn off is performed when the short circuit current becomes zero due to reverse charging of the first and second capacitors C1 and C2, so the turn OFF There is almost no loss.

In addition, the capacitor capacity of the auxiliary circuit may be small, and the size can be reduced. In addition, some increase in the parasitic impedance component of the auxiliary circuit can be tolerated. In addition, it is possible to repeatedly shut off and restart the direct current.

[Embodiment 9]
FIG. 32 shows a main circuit configuration of the ninth embodiment. In the ninth embodiment, the eighth and ninth semiconductor switching devices T8 and T9 of the eighth embodiment are replaced with switching devices having a reverse blocking capability that can not be self-extinguished such as thyristors. Further, the fifth and sixth diodes D5 and D6 of the eighth embodiment are omitted.

The operation of the ninth embodiment is the same as that of the eighth embodiment. However, as shown in FIG. 29, since the unnecessary current flows through the ninth semiconductor switching element T9 and the second resistor R2 by turning on the ninth semiconductor switching element T9 after opening the mechanical circuit breaker CB, self-arc-extinguishing Without the ability, the ninth semiconductor switching element T9 can not be turned off by the command signal from the host controller.

However, a normal thyristor is turned off when the gate current is zero and the forward current is less than the holding current. Therefore, the values of the first and second resistors R1 and R2 are increased, and the unnecessary current flowing through the first and second resistors R1 and R2 is smaller than the holding current when the eighth and ninth semiconductor switching elements T8 and T9 are ON. If so, the eighth and ninth semiconductor switching elements T8 and T9 can be replaced with thyristors.

As described above, according to the ninth embodiment, the same function and effect as the eighth embodiment can be obtained. In addition, the thyristor has a smaller voltage drop than the IGBT, and it is easy to obtain high breakdown voltage and high current products. Further, since there are parts of the thyristor which withstand voltage is higher than that of the IGBT, the number of series connection may be smaller than that of the IGBT. Therefore, high withstand voltage and large current can be achieved with smaller size and lower cost than IGBT, and loss and heat generation at the time of interruption can be reduced.

Tenth Embodiment
FIG. 33 shows a main circuit configuration of the tenth embodiment. The tenth embodiment is characterized in that a self-ignitionable tenth semiconductor switching element T10 is interposed between the first and second resistors R1 and R2 of the ninth embodiment and the negative terminals of the first and second DC systems 1 and 2. It is added to cut off the unnecessary current.

Hereinafter, the operation of the direct current cut-off device 3 in the tenth embodiment will be described. In the steady state, the tenth semiconductor switching element T10 is turned on to charge the first and second capacitors C1 and C2 in the same state as shown in FIG. When the shutoff command comes due to completion of charging or a short circuit accident, the tenth semiconductor switching element T10 is turned off.

The completion of charging is detected on the condition that the voltage across the first and second capacitors C1 and C2 is detected and equal to the grid voltage. Alternatively, the time constant is obtained from the product of the first capacitor C1 and the first resistor R1 and the second capacitor C2 and the second resistor R2, and the time from the closing of the mechanical circuit breaker CB is sufficiently longer than the time constant (for example, about 10 times) It may be determined that charging is completed by the lapse of.

After the arc extinguishing, the tenth semiconductor switching device T10 is OFF, and unlike in FIG. 29, the unnecessary current flowing through the ninth semiconductor switching device T9 and the second resistor R2 is interrupted by the tenth semiconductor switching device T10. .

As described above, according to the tenth embodiment, the same function and effect as the eighth and ninth embodiments can be obtained. Also, the loss after current interruption can be made zero. In addition, since the unnecessary current does not flow even if the resistance values of the first and second resistors R1 and R2 are small, the eighth and ninth semiconductor switching elements (thyristors) T8 and T9 can be reliably turned OFF. As a merit of reducing the resistance value of the first and second resistors R1 and R2, the recharging speed of the first and second capacitors C1 and C2 at the time of reconnection of the system in FIG. 30 is improved. Thus, it is possible to shorten the time taken to complete the blocking preparation.

The tenth semiconductor switching element T10 may be divided into a tenth semiconductor switching element T10 for charging the first capacitor C1 and an eleventh semiconductor switching element T11 for charging the second capacitor C2. In this case, the first resistor R1 and the tenth semiconductor switching element T10 are connected. In addition, the second resistor R2 and the eleventh semiconductor switching element T11 are connected. In addition, command signals from upper controllers of the tenth semiconductor switching device T10 and the eleventh semiconductor switching device T11 may be shared.

[Embodiment 11]
In the eighth to tenth embodiments, the first and second capacitors C1 and C2 of the auxiliary circuit are charged in advance, and the capacitor discharge current is used to cancel the current at the time of opening the mechanical circuit breaker to create a zero point to extinguish the arc. Arc. However, as shown in FIG. 27, since the charging current of the first and second capacitors C1 and C2 flows through the first and second resistors R1 and R2, there is a problem that power loss occurs in each of the resistors.

Hereinafter, the direct current shutoff device 3 according to the eleventh embodiment will be described with reference to FIG. The DC circuit breaker 3 according to the eleventh embodiment includes the mechanical circuit breaker CB, the first and second capacitors C1 and C2, the third and fourth auxiliary circuit

current switch units

6 and 7, and the twelfth and thirteenth semiconductor switching devices. Elements T12 and T13, third to sixth reactors L3 to L6, and seventh and eighth diodes D7 and D8 are provided. Here, the third and fourth auxiliary circuit

current switch sections

6 and 7 are assumed to be eighth and ninth semiconductor switching elements T8 and T9 (thyristors).

A first capacitor C1 and a third reactor L3 are provided between the + terminal of the first DC system 1 and the common connection point of the mechanical circuit breaker CB and the − terminals of the first and second DC systems 1 and 2. A fifth reactor (first impedance) L5 and a twelfth semiconductor switching element T12 having a self arc extinguishing capability are sequentially connected in series. The order of connection of the first capacitor C1 and the third reactor L3 may be reversed.

In FIG. 34, the twelfth semiconductor switching element T12 is an IGBT, and its collector terminal is connected to the fifth reactor L5, and its emitter terminal is connected to the − terminal side of the first and second DC systems 1 and 2.

The anode of an eighth semiconductor switching device (thyristor in FIG. 34) having reverse blocking capability is connected to the common connection point between the positive terminal of the second DC system 2 and the mechanical circuit breaker CB. The cathode of the eighth semiconductor switching element (thyristor) T8 is connected to the common connection point of the third and fifth reactors L3 and L5.

An anode of a seventh diode D7 is connected to a common connection point of the fifth reactor L5 and the twelfth semiconductor switching element T12. The cathode of the seventh diode D7 is connected to the common connection point between the eighth semiconductor switching element (thyristor) T8 and the positive terminal of the second DC system 2.

A second capacitor C2 and a fourth reactor L4 are provided between the + terminal of the second DC system 2 and the common connection point of the mechanical circuit breaker CB and the − terminals of the first and second DC systems 1 and 2. A sixth reactor (second impedance) L6 and a thirteenth semiconductor switching element T13 having a self arc extinguishing capability are sequentially connected in series. The order of connection of the second capacitor C2 and the fourth reactor L4 may be reversed.

In FIG. 34, the thirteenth semiconductor switching element T13 is an IGBT, and its collector terminal is connected to the sixth reactor L6, and its emitter terminal is connected to the-terminal side of the first and second DC systems 1 and 2.

The anode of a ninth semiconductor switching device (a thyristor in FIG. 34) having reverse blocking capability is connected to the common connection point between the positive terminal of the first DC system 1 and the mechanical circuit breaker CB. The cathode of the ninth semiconductor switching element (thyristor) T9 is connected to the common connection point of the fourth and sixth reactors L4 and L6.

An anode of an eighth diode D8 is connected to a common connection point of the sixth reactor L6 and the thirteenth semiconductor switching element T13. The cathode of the eighth diode D8 is connected to the common connection point of the ninth semiconductor switching element (thyristor) T9 and the positive terminal of the first DC system 1.

The eighth and ninth semiconductor switching devices T8 and T9 do not require the self arc-extinguishing capability but need the reverse blocking capability. Other switching elements such as a series circuit of an IGBT and a diode or a reverse blocking IGBT may be substituted.

Hereinafter, the operation of the direct current shutoff device 3 in the fourth embodiment will be described. In the steady state, the mechanical circuit breaker CB is closed, and current flows in both directions. In this steady state, the first and second capacitors C1 and C2 are charged by switching the twelfth and thirteenth semiconductor switching elements T12 and T13.

FIG. 35 shows a state in which the twelfth and thirteenth semiconductor switching elements T12 and T13 are turned ON. The capacitor charging current flows through the first capacitor C1 → the third reactor L3 → the fifth reactor L5 → the twelfth semiconductor switching element T12, and the first capacitor C1 is charged. At the same time, the capacitor charging current flows through the second capacitor C2 → the fourth reactor L4 → the sixth reactor L6 → the thirteenth semiconductor switching element T13, and the second capacitor C2 is charged.

FIG. 36 shows a state in which the twelfth and thirteenth semiconductor switching elements T12 and T13 are turned off. The magnetic energy stored in the fifth reactor L5 at the time of turning on the twelfth semiconductor switching element T12 circulates the seventh diode D7 → the first capacitor C1 → the third reactor L3 to flow a current, and the first capacitor C1 is charged.

In addition, the magnetic energy stored in the sixth reactor L6 when the thirteenth semiconductor switching element T13 is ON circulates the eighth diode D8 → the second capacitor C2 → the fourth reactor L4, and the second capacitor C2 is charged. Ru.

When charging is completed, the twelfth and thirteenth semiconductor switching elements T12 and T13 maintain the OFF state. Since the current passes only through the mechanical circuit breaker CB under constant conditions, there is almost no power loss.

The completion of charging is determined by detecting the voltage across the first and second capacitors C1 and C2 and having reached a predetermined voltage. As another method, the time until the first and second capacitors C1 and C2 are completely charged is calculated in advance from the constants of the third to sixth reactors L3 to L6 and the first and second capacitors C1 and C2. The twelfth and thirteenth semiconductor switching elements T12 and T13 may be turned off when the time is reached.

The direct current | flow interruption | blocking apparatus 3 of this Embodiment 11 in case an accident generate | occur | produces in FIG. 37 at the 2nd direct current | flow system 2 side is shown. When an accident occurs, the ninth semiconductor switching element T9 is turned ON, and a discharge current flows from the second capacitor C2 as an auxiliary circuit current via the mechanical circuit breaker CB → the ninth semiconductor switching element T9 → the fourth reactor L4. The auxiliary circuit current cancels the short circuit current flowing through the mechanical circuit breaker CB to create a current zero, and opens the mechanical circuit breaker CB to extinguish the arc.

The direct current | flow interruption | blocking apparatus 3 of this Embodiment 11 after arc extinguishing is shown in FIG. The auxiliary circuit current flows via the ninth semiconductor switching element T9 → the fourth reactor L4 → the second capacitor C2, and charges the second capacitor C2 in the reverse direction to that in FIG. When the charging of the second capacitor C2 is completed, the current on the second DC system 2 side becomes zero, and the interruption of the current is completed.

Unlike the eighth and ninth embodiments, unnecessary current does not flow in the direct current cutoff device 3 of the eleventh embodiment. Therefore, even if the ninth semiconductor switching element T9 does not have the self arc extinguishing ability (even if the holding current is large), it can be turned off with certainty.

FIG. 39 shows the DC interrupting device 3 of Embodiment 11 when the current interrupting is completed and the second DC system 2 is turned on again. When the mechanical circuit breaker CB is closed, a resonant circuit is formed in the path of the second capacitor C2 → the fourth reactor L4 → the sixth reactor L6 → the eighth diode D8 → the mechanical circuit breaker CB, and a resonant current flows, and the second capacitor C2 is recharged to its original orientation.

When the charging of the second capacitor C2 is completed, the resonance current is blocked by the eighth diode D8, the steady state is reached, and the preparation for cutoff is completed. If charging of the second capacitor C2 is incomplete, the second capacitor C2 can be charged by turning on the thirteenth semiconductor switching element T13.

In the eleventh embodiment, the shutoff method in the case where an accident occurs on the second DC system 2 side is described, but it is possible to shut off similarly in the case where an accident occurs on the first DC system 1 side. In this case, by turning on the eighth semiconductor switching element T9 instead of the ninth semiconductor switching element T9, the short circuit current passing through the mechanical circuit breaker CB is canceled using the discharge current of the first capacitor C1.

The twelfth semiconductor switching device T12 and the thirteenth semiconductor switching device T13 may be shared. In that case, the semiconductor switching element made common is the same connection configuration as the tenth semiconductor switching element T10 of FIG.

The eleventh embodiment exhibits the same effects as the eighth to tenth embodiments. In addition, in the direct current cutoff device 3 of the eleventh embodiment, the capacitor charging current does not flow through the resistor, and a power loss due to the resistor does not occur, so the loss at the time of charging can be reduced.

Further, at the time of system reconnection, the recharging of the first and second capacitors C1 and C2 is completed only by closing the mechanical circuit breaker CB.

Although the present invention has been described in detail with reference to the specific examples described above, it is obvious to those skilled in the art that various variations and modifications are possible within the scope of the technical idea of the present invention. It is natural that such variations and modifications fall within the scope of the claims.

Claims

First and second mechanical circuit breakers connected in series between the + terminal of the first DC system and the + terminal of the second DC system;
A first auxiliary circuit current switch unit having a first semiconductor switching element, one end of which is connected to a common connection point of the positive terminal of the first DC system and the first mechanical circuit breaker;
It has a second semiconductor switching element, one end is connected to the other end of the first auxiliary circuit current switch portion, and the other end is connected to the common connection point of the + terminal of the second DC system and the second mechanical circuit breaker The second auxiliary circuit current switch unit,
A capacitor connected between a common connection point of the first and second mechanical circuit breakers and a common connection point of the first and second auxiliary circuit current switch parts;
A first reactor connected in series to the capacitor;
An impedance connected between a common connection point of the first and second auxiliary circuit current switch parts and a negative terminal of the first and second DC systems;
DC interrupting device with.
The DC interrupting device according to claim 1, wherein the impedance is a resistor.
The direct current cut-off device according to claim 2, wherein the first and second semiconductor switching elements are thyristors.
The first and second auxiliary circuit current switch parts have diodes connected in series to the first and second semiconductor switching elements, and the first and second semiconductor switching elements have self-extinguishing ability. The direct current | flow interruption | blocking apparatus of Claim 2.
5. The DC interrupting device according to claim 2, wherein a Zener diode is connected between the resistor and negative terminals of the first and second DC systems.
The direct current cut-off device according to claim 3, wherein a third semiconductor switching element is connected between the resistor and negative terminals of the first and second direct current systems.
The impedance is a second reactor,
A diode connected in parallel to the second reactor,
A third semiconductor switching element connected between the second reactor and negative terminals of the first and second DC systems;
The DC interrupting device according to claim 1, comprising:
First and second mechanical circuit breakers connected in series between the-terminal of the first DC system and the-terminal of the second DC system;
A first auxiliary circuit current switch unit having a first semiconductor switching element, one end of which is connected to a common connection point of the negative terminal of the first DC system and the first mechanical circuit breaker;
It has a second semiconductor switching element, and one end is connected to the other end of the first auxiliary circuit current switch portion, and the other end is connected to the common connection point of the − terminal of the second DC system and the second mechanical circuit breaker The second auxiliary circuit current switch unit,
A capacitor connected between a common connection point of the first and second mechanical circuit breakers and a common connection point of the first and second auxiliary circuit current switch parts;
A first reactor connected in series to the capacitor;
An impedance connected between a common connection point of the first and second auxiliary circuit current switch parts and a + terminal of the first and second DC systems;
DC interrupting device with.
When current flows from the first DC system to the second DC system and an accident occurs in the second DC system, the first semiconductor switching element is turned on, and the current flowing to the first mechanical circuit breaker Shuts off the first mechanical circuit breaker after the value of
When current flows from the second DC system to the first DC system and an accident occurs in the first DC system, the second semiconductor switching element is turned on, and the current flows to the second mechanical circuit breaker The direct current cut-off device according to any one of claims 1 to 7, wherein the second mechanical circuit breaker is cut off after the value of s becomes equal to or less than a predetermined value.
A third diode in which an anode is connected to a common connection point of the first and second mechanical circuit breakers, and a cathode is connected to a common connection point of the first mechanical circuit breaker and the first auxiliary circuit current switch portion;
A fourth diode whose anode is connected to the common connection point of the first and second mechanical circuit breakers and whose cathode is connected to the common connection point of the second mechanical circuit breaker and the second auxiliary circuit current switch unit;
The DC interrupting device according to claim 1, comprising:
When current flows from the first DC system to the second DC system and a short circuit occurs in the second DC system, the first semiconductor switching element is turned on to flow an auxiliary circuit current, and the auxiliary circuit Interrupt the first mechanical circuit breaker during a period when the current is greater than the short circuit current,
When a current flows from the second DC system to the first DC system and a short circuit occurs in the first DC system, the second semiconductor switching element is turned on to flow the auxiliary circuit current, and the auxiliary circuit 11. The DC circuit breaker according to claim 10, wherein the second mechanical circuit breaker is shut off during a period when the current is greater than the short circuit current.
The DC circuit breaker according to claim 1, wherein fourth and fifth semiconductor switching elements having a self-ignition capability are connected in parallel to the first and second mechanical circuit breakers.
When current flows from the first DC system to the second DC system and a short circuit occurs in the second DC system, the fourth semiconductor switching element is turned on and then the first mechanical circuit breaker is opened. Command a pole, and then turn on the first semiconductor switching element,
When current flows from the second DC system to the first DC system and a short circuit occurs in the first DC system, the fifth semiconductor switching element is turned on, and then the second mechanical circuit breaker is opened. The direct current cut-off device according to claim 12, wherein a pole command is issued and then the second semiconductor switching element is turned on.
A sixth semiconductor switching element having no self arc extinguishing capability connected in anti-parallel to the third diode;
A seventh semiconductor switching element not having a self arc extinguishing capability connected antiparallel to the fourth diode;
The direct current cut-off device according to claim 10, comprising:
When current flows from the first DC system to the second DC system and a short circuit occurs in the second DC system, the sixth semiconductor switching element is turned on, and then the first mechanical circuit breaker is opened. The pole command is performed, and then the sixth semiconductor switching element is turned off, and then the first semiconductor switching element is turned on,
When current flows from the second DC system to the first DC system and a short circuit occurs in the first DC system, the seventh semiconductor switching element is turned on, and then the second mechanical circuit breaker is opened. The direct current cut-off device according to claim 14, wherein a pole command is issued, then an off command of the seventh semiconductor switching element is issued, and then the second semiconductor switching element is turned on.
A third diode in which a cathode is connected to a common connection point of the first and second mechanical circuit breakers, and an anode is connected to a common connection point of the first mechanical circuit breaker and the first auxiliary circuit current switch portion;
A fourth diode whose cathode is connected to the common connection point of the first and second mechanical circuit breakers and whose anode is connected to the common connection point of the second mechanical circuit breaker and the second auxiliary circuit current switch unit;
The DC interrupting device according to claim 8, comprising:
9. The DC circuit breaker according to claim 8, wherein fourth and fifth semiconductor switching elements having a self-ignition capability are connected in parallel to the first and second mechanical circuit breakers.
A sixth semiconductor switching element having no self arc extinguishing capability connected in anti-parallel to the third diode;
A seventh semiconductor switching element not having a self arc extinguishing capability connected antiparallel to the fourth diode;
The direct current cut-off device according to claim 16, comprising
A mechanical circuit breaker connected between the + terminal of the first DC system and the + terminal of the second DC system;
A first capacitor sequentially connected in series between the common connection point of the positive terminal of the first DC system and the mechanical circuit breaker, and the common connection point of the positive terminal of the second DC system and the mechanical circuit breaker; A third reactor and a third auxiliary circuit current switch unit, or a third reactor, a first capacitor and a third auxiliary circuit current switch unit;
A second capacitor sequentially connected in series between the common connection point of the + terminal of the second DC system and the mechanical circuit breaker, and the common connection point of the positive terminal of the first DC system and the mechanical circuit breaker A fourth reactor and a fourth auxiliary circuit current switch unit, or a fourth reactor, a second capacitor and a fourth auxiliary circuit current switch unit;
Common connection point of the third reactor and the third auxiliary circuit current switch unit, or common connection point of the first capacitor and the third auxiliary circuit current switch unit, and-terminals of the first and second DC systems And a first impedance connected between
Common connection point of the fourth reactor and the fourth auxiliary circuit current switch unit, or common connection point of the second capacitor and the fourth auxiliary circuit current switch unit, and-terminals of the first and second DC systems And a second impedance connected between
DC interrupting device with.
The direct current cut-off device according to claim 19, wherein the first impedance and the second impedance are a first resistance and a second resistance.
The third auxiliary circuit current switch unit includes an eighth semiconductor switching element of a self-arc-extinguishing type element and a fifth diode connected in series to the eighth semiconductor switching element,
21. The DC circuit breaker according to claim 20, wherein the fourth auxiliary circuit current switch portion has a ninth semiconductor switching element of a self arc extinguishing element and a sixth diode connected in series to the ninth semiconductor switching element.
The third auxiliary circuit current switch unit includes an eighth semiconductor switching element not having a self-extinguishing ability,
The direct current cut-off device according to claim 20, wherein the fourth auxiliary circuit current switch unit comprises a ninth semiconductor switching element having no self arc-extinguishing ability.
A tenth semiconductor switching element connected between the first and second resistors and the negative terminals of the first and second DC systems; or the first resistor and the first and second DC systems A tenth semiconductor switching element connected between the − terminal and the eleventh semiconductor switching element connected between the second resistor and the − terminals of the first and second DC systems; The direct current | flow interruption | blocking apparatus of Claim 22.
The first impedance and the second impedance are a fifth reactor and a sixth reactor,
A twelfth semiconductor switching element connected between the fifth and sixth reactors and the-terminals of the first and second DC systems, or-of the fifth reactor and the first and second DC systems A twelfth semiconductor switching device connected between the terminals and a thirteenth semiconductor switching device connected between the sixth reactor and negative terminals of the first and second DC systems;
An anode is connected to a common connection point of the fifth reactor and the twelfth semiconductor switching element, and a seventh is connected to a common connection point of a third auxiliary circuit current switch portion and a positive terminal of the second DC system. A diode,
An anode is connected to a common connection point of the sixth reactor and the thirteenth semiconductor switching element or the twelfth semiconductor switching element, and a cathode is a common connection of the fourth auxiliary circuit current switch portion and the positive terminal of the first DC system. An eighth diode connected to the point,
The direct current cut-off device according to claim 19, comprising:
The third auxiliary circuit current switch unit includes an eighth semiconductor switching element not having a self-extinguishing ability,
25. The DC interrupting device according to claim 24, wherein the fourth auxiliary circuit current switch unit comprises a ninth semiconductor switching element having no self arc-extinguishing capability.
When current flows from the first DC system to the second DC system and an accident occurs in the second DC system, the fourth auxiliary circuit current switch unit is turned on to flow the current flowing to the mechanical circuit breaker Shuts off the mechanical circuit breaker after the value of
When current flows from the second DC system to the first DC system, and an accident occurs in the first DC system, the third auxiliary circuit current switch unit is turned on, and current flows to the mechanical circuit breaker The direct current shutoff device according to any one of claims 19 to 25, which shuts off the mechanical circuit breaker after the value of 以下 falls below a predetermined value.