WO2013164874A1

WO2013164874A1 - Dc circuit breaker

Info

Publication number: WO2013164874A1
Application number: PCT/JP2012/061530
Authority: WO
Inventors: 和順田畠; 伊藤　弘基; 邦夫菊池; 健次亀井; 雄作堀之内; 正樹平塚; 翔常世田; 敏信武田
Original assignee: 三菱電機株式会社
Priority date: 2012-05-01
Filing date: 2012-05-01
Publication date: 2013-11-07

Abstract

The purpose of the present invention is to provide a DC circuit breaker for which it is possible to reduce the size and the cost thereof. This DC circuit breaker is provided with: a cutoff section (2) that is inserted into a DC line (1) and that serves as a current path for DC current while in a steady state; and a commutation circuit (4) that commutates DC current after opening of the cutoff section (2). The commutation circuit (4) is provided with: a series resonance circuit (20) comprising a capacitor (5) and a reactor (6); a charging resistor (8) that is a charging circuit (22) for charging the capacitor (5) using the DC potential of the DC line (1) while in a stable state; and a commutation switch section (21) that, after opening of the cutoff section (2), connects the cutoff section (2) and the series resonance circuit (20) in parallel and superimposes the resonant current generated by the series resonance circuit (20) on the DC current, and after current cutoff by the cutoff section (2), cuts off the small amount of current flowing to the DC line (1) via the series resonance circuit (20).

Description

DC circuit breaker

The present invention relates to a direct current circuit breaker that interrupts direct current.

Conventionally, in a DC circuit breaker that cuts off DC current, a current zero point is formed by superimposing a resonant current from a commutation circuit composed of a capacitor and a reactor, and the DC current is cut off at the current zero point. As such a DC circuit breaker, for example, comprising a charging circuit comprising an AC power supply and a rectifier for charging the capacitor of the above-mentioned commutation circuit, discharging the charge of the capacitor charged in advance by the charging circuit, A technique for forming a current zero by superimposing a resonant current on a direct current is disclosed (for example, Patent Document 1).

Japanese Patent No. 4660131

However, the above-described conventional technique has a problem that the DC circuit breaker is increased in size and cost because the above-described charging circuit is required to charge the capacitor of the commutation circuit.

The present invention has been made in view of the above, and an object thereof is to provide a DC circuit breaker that can be reduced in size and cost.

In order to solve the above-described problems and achieve the object, a DC circuit breaker according to the present invention forms a current zero point by superimposing a resonant current on a DC current flowing in a DC line, and the DC current is generated at the current zero point. A DC circuit breaker for interrupting, wherein the circuit is inserted into the DC line and serves as a flow path for the DC current in a steady state; and a commutation circuit that commutates the DC current after opening of the circuit breaker. The commutation circuit includes a series resonant circuit composed of a capacitor and a reactor, a charging circuit for charging the capacitor with a DC potential of the DC line in a steady state, and after opening the blocking unit, The interruption unit and the series resonance circuit are connected in parallel, and the resonance current generated by the series resonance circuit is superimposed on the direct current, and after the current interruption of the interruption unit, the current is passed through the series resonance circuit. Characterized in that it comprises a commutation switch portion for cutting the micro-current flowing in the DC line, the.

According to the present invention, there is an effect that the DC circuit breaker can be reduced in size and cost.

FIG. 1 is a diagram illustrating a configuration example of the DC circuit breaker according to the first embodiment. FIG. 2 is a diagram illustrating an operation of the DC circuit breaker according to the first embodiment when a DC current is interrupted. FIG. 3 is a diagram of a configuration example of the DC circuit breaker according to the second embodiment. FIG. 4 is a diagram of a configuration example of the DC circuit breaker according to the third embodiment. FIG. 5 is a diagram of a configuration example of a DC circuit breaker according to the fourth embodiment. FIG. 6 is a diagram of a configuration example of the DC circuit breaker according to the fifth embodiment. FIG. 7 is a diagram of a configuration example of the DC circuit breaker according to the sixth embodiment. FIG. 8 is a diagram of a configuration example of a DC circuit breaker according to the seventh embodiment. FIG. 9 is a diagram of a configuration example of the DC circuit breaker according to the eighth embodiment.

Hereinafter, a DC circuit breaker according to an embodiment of the present invention will be described with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

Embodiment 1 FIG.
FIG. 1 is a diagram of a configuration example of the DC circuit breaker according to the first embodiment. As shown in FIG. 1, the DC circuit breaker according to the first embodiment is inserted into the DC line 1, and a DC current is passed after the circuit breaker 2 is opened, and the DC circuit 1 has a DC current flow path in a steady state. And a commutation circuit 4 for commutation.

The commutation circuit 4 includes a series resonance circuit 20 including a capacitor 5 and a reactor 6, and a series circuit including a disconnecting portion 3 and a discharge gap 7 that connect the cutoff portion 2 and the series resonance circuit 20 in parallel after the opening of the cutoff portion 2. And a charging resistor 8 which is a charging circuit 22 for charging the capacitor 5 with the DC potential of the DC line 1 in a steady state.

In the present embodiment, the discharge gap 7 has a duty of supplying a resonant current to superimpose the resonant current on the direct current flowing in the direct current line 1, and the disconnecting portion 3 is connected to the commutation circuit 4 after the current cutoff of the interrupting portion 2. And a minute current cutting duty for cutting a minute current flowing through the DC line 1 via the.

Next, the operation of the DC circuit breaker according to the first embodiment when the DC current is interrupted will be described with reference to FIG. 1 and FIG. FIG. 2 is a diagram illustrating an operation of the DC circuit breaker according to the first embodiment when a DC current is interrupted. The example shown in FIG. 2 shows an example in which current (1 pu) flows from the left end side to the right end side of the DC circuit breaker, as indicated by solid arrows in FIG. In the present embodiment, the capacitor 5 is charged with the DC potential of the DC line 1 via the charging resistor 8 in a steady state. Moreover, at the time of steady state, the interruption | blocking part 2 and the disconnection part 3 are close-controlled, and the discharge gap 7 is open-controlled.

As shown in FIG. 2, when a fault occurs in the DC line 1 at time t1 (= 0.1 s) (here, for example, a ground fault on the right end side of the DC breaker shown in FIG. 1), A fault current several times the steady-state current (1 pu) determined by the circuit conditions up to the fault point and the value of the ground resistance flows, and the breaker 2 starts the opening operation based on the opening command from the control circuit (not shown) To do. Here, when the opening time until the breaking portion 2 is opened is 0.1 s, the breaking portion 2 is mechanically opened at time t2 (= 0.2 s).

At this time, when a close control command to the discharge gap 7 is output from a control circuit (not shown) and the discharge gap 7 is closed, the charge of the capacitor 5 charged by the DC potential of the DC line 1 is discharged, and FIG. As indicated by broken line arrows, a resonant current flows through the loop of the capacitor 5, the cutoff part 2, the disconnection part 3, the discharge gap 7, and the reactor 6. This resonant current is superimposed on the accident current flowing in the DC line 1, and when the current zero point is formed at time t3 as shown in FIG. 2, the arc of the interrupting unit 2 is extinguished and the current is interrupted. Is done. In addition, what is necessary is just to make it connect and absorb a surge absorber in parallel with the interruption | blocking part 2 about the overvoltage which generate | occur | produces between the poles of the interruption | blocking part 2 after electric current interruption | blocking.

After that, that is, even after the current interruption of the interruption unit 2, since a minute current continues to flow through the DC line 1 via the commutation circuit 4, a disconnection command is output from a control circuit (not shown) in order to remove this minute current. Thus, the disconnecting portion 3 is controlled to be opened. By the above operation, the interruption of the accident current is completed.

As described above, the DC circuit breaker according to the first embodiment includes the charging resistor that is a charging circuit for charging the capacitor of the series resonance circuit with the DC potential of the DC line. The current zero point formed by charging the capacitor with the DC potential of the DC line through the resistance for the DC line and discharging the capacitor charge and superimposing the resonant current on the fault current flowing in the DC line when the DC current is interrupted Therefore, it is not necessary to separately provide a charging circuit including an AC power source and a rectifier to charge the capacitor, and it is possible to realize a reduction in size and cost of the DC circuit breaker.

In the first embodiment described above, the example in which the discharge gap is closed at the opening time of the breaking unit has been described. However, after the opening of the breaking unit, the resonance current generated by the series resonance circuit is superimposed on the accident current and Needless to say, the time at which the discharge gap is controlled to close may be set to the time before and after the opening time of the blocking portion within a range where the zero point can be formed.

In the first embodiment described above, an example in which the surge absorber absorbs the overvoltage generated at both ends of the interrupting part after interrupting the current is described. However, depending on the withstand voltage of the interrupting part and other circuit conditions, the surge absorber is provided. The structure which does not do may be sufficient.

Embodiment 2. FIG.
FIG. 3 is a diagram of a configuration example of the DC circuit breaker according to the second embodiment. In addition, since each component of the DC circuit breaker according to the second embodiment is the same as each component of the DC circuit breaker according to the first embodiment, description thereof is omitted here.

In the present embodiment, as shown in FIG. 3, the disconnecting section 3 described in the first embodiment is connected in series with the blocking section 2 and inserted into the DC line 1. Even in such a configuration, the accident current can be interrupted by the same operation as in the first embodiment, and the same effect as in the first embodiment can be obtained.

As described above, according to the DC circuit breaker of the second embodiment, even in the configuration in which the disconnecting portion is connected in series with the interrupting portion and inserted into the DC line, the capacitor is connected as in the first embodiment. There is no need to provide a separate charging circuit including an AC power source and a rectifier for charging, and the DC circuit breaker can be reduced in size and cost.

Embodiment 3 FIG.
FIG. 4 is a diagram of a configuration example of the DC circuit breaker according to the third embodiment. In addition, the same code | symbol is attached | subjected to the component which is the same as that of Embodiment 1, or equivalent, and the detailed description is abbreviate | omitted.

In the present embodiment, as shown in FIG. 4, the commutation switch unit 21 described in the first embodiment is configured using only the opening / closing unit (first opening / closing unit) 9.

The operation of the DC circuit breaker according to this embodiment when the DC current is interrupted will be described. In the present embodiment, the open / close unit 9 is controlled to be opened in the steady state, and the DC resonance time by the series resonance circuit 20 after the opening of the blocking unit 2 or after the opening of the blocking unit 2 is interrupted. The opening / closing part 9 is closed and controlled at a time around the opening time of the breaking part 2 within a range in which the current can be superimposed on the accident current to form a current zero point.

Thereafter, in order to remove the minute current that continues to flow through the commutation circuit 4 after the current interruption of the interruption unit 2, the opening / closing unit 9 is controlled to open. By the above operation, the interruption of the accident current is completed.

In other words, in the present embodiment, the opening / closing unit 9 has both the duty for supplying the resonant current in the discharge gap 7 described in the first embodiment and the duty for cutting the minute current in the disconnecting unit 3.

As described above, according to the direct current circuit breaker of the third embodiment, the commutation switch unit is configured such that the switching unit has both the duty of supplying the resonant current in the discharge gap and the duty of cutting the minute current in the disconnecting part. Even in this case, as in the first embodiment, there is no need to provide a separate charging circuit including an AC power source and a rectifier to charge the capacitor, and the DC circuit breaker can be reduced in size and cost. Become.

Embodiment 4 FIG.
FIG. 5 is a diagram of a configuration example of a DC circuit breaker according to the fourth embodiment. In addition, the same code | symbol is attached | subjected to the component which is the same as that of Embodiment 2, or equivalent, and the detailed description is abbreviate | omitted.

In the present embodiment, as shown in FIG. 5, instead of the discharge gap 7 described in the second embodiment, an open / close section (second open / close section) 9a having only a resonance current input duty is provided. Yes.

In the present embodiment, the opening / closing unit 9 a has a duty of supplying a resonant current to superimpose the resonant current on the DC current flowing through the DC line 1, and the disconnecting unit 3 is connected to the commutation circuit 4 after the current blocking of the blocking unit 2. And a minute current cutting duty for cutting a minute current flowing through the DC line 1 via the.

In the second embodiment, when an air discharge gap is used as the discharge gap 7, it can be configured at a low cost, but the sound when a resonant current is applied is increased. In the present embodiment, instead of the discharge gap 7, by using the opening / closing part 9a having only the responsibility for supplying the resonant current, it is possible to achieve both the reduction of the noise and the reduction of the cost when the resonant current is applied. It becomes possible.

As described above, according to the DC circuit breaker of the fourth embodiment, in place of the discharge gap described in the second embodiment, by having a configuration including an opening / closing portion having only a resonance current input duty, In addition to the effects of the first to third embodiments described above, it is possible to achieve both noise reduction and cost reduction when a resonant current is input.

Embodiment 5. FIG.
FIG. 6 is a diagram of a configuration example of the DC circuit breaker according to the fifth embodiment. In addition, the same code | symbol is attached | subjected to the component which is the same as that of Embodiment 2, or equivalent, and the detailed description is abbreviate | omitted.

In this embodiment, as shown in FIG. 6, the charging circuit 22 of the capacitor 5 has a configuration in which a charging switch 10 is connected in series with the charging resistor 8.

The operation of the DC circuit breaker according to this embodiment when the DC current is interrupted will be described. In the present embodiment, the charging opening / closing part 10 is controlled to be closed to charge the capacitor 5 in a steady state, and the charging opening / closing part 10 is controlled to open in the event of an accident.

By controlling in this way, it is possible to prevent the electric charge of the capacitor 5 from being discharged through the charging resistor 8 from the time of the accident until the discharge gap 7 is closed.

For example, when it is necessary to charge the capacitor 5 in a short time in a steady state, that is, when having a duty of high-speed shut-off, it is necessary to reduce the charging time constant by the capacitor 5 and the charging resistor 8. In such a case, in the configuration that does not include the charging opening / closing part 10, the charge of the capacitor 5 is discharged through the charging resistor 8 when an accident occurs, and the peak value of the resonant current superimposed on the accident current is small. Therefore, there is a possibility that the current zero point cannot be formed.

In the present embodiment, when the accident occurs, by controlling the opening of the charging switch 10, it is possible to prevent the capacitor 5 from discharging from the time of the accident until the discharge gap 7 is closed, Even when the charging time constant by the capacitor 5 and the charging resistor 8 needs to be reduced, the current zero point can be reliably formed.

In the example illustrated in FIG. 6, the example in which the charging opening / closing unit 10 is connected in series with the charging resistor 8 is described with respect to the configuration of the second embodiment illustrated in FIG. 3. The present invention can also be applied to the first or third to fourth embodiments.

As described above, according to the DC circuit breaker of the fifth embodiment, since the charging switch is connected in series with the charging resistor, in addition to the effects of the above-described first to fourth embodiments, a constant value is provided. At all times, it is necessary to close the charging switch and charge the capacitor, and in the event of an accident, open the charging switch to reduce the charging time constant between the capacitor and the charging resistor. Even in some cases, the current zero point can be reliably formed and the DC current can be interrupted.

Embodiment 6 FIG.
FIG. 7 is a diagram of a configuration example of the DC circuit breaker according to the sixth embodiment. In addition, the same code | symbol is attached | subjected to the component which is the same as that of Embodiment 2, or equivalent, and the detailed description is abbreviate | omitted.

In the present embodiment, as shown in FIG. 7, the charging circuit 22 for the capacitor 5 is configured by connecting a charging opening / closing unit 10 instead of the charging resistor 8 in the second embodiment, that is, the fifth embodiment. The resistance value of the charging resistor 8 in FIG.

With this configuration, the charging time constant of the capacitor 5 is further shortened as compared with the fifth embodiment. Therefore, it is more suitable than the case of the fifth embodiment when it is necessary to charge the capacitor 5 in a short time in a steady state, that is, when it has a higher-speed cutoff duty than the fifth embodiment.

In the example illustrated in FIG. 7, the example in which the charging opening / closing unit 10 is connected instead of the charging resistor 8 is described with respect to the configuration of the second embodiment illustrated in FIG. 3. Similarly, the present invention can be applied to the configurations of the first embodiment or the third to fourth embodiments.

As described above, according to the DC circuit breaker of the sixth embodiment, the charging switch is connected in place of the charging resistor, so that it has a higher-speed disconnection duty than the above-described fifth embodiment. Even in this case, the current zero point can be surely formed and the direct current interruption can be performed.

Embodiment 7 FIG.
FIG. 8 is a diagram of a configuration example of a DC circuit breaker according to the seventh embodiment. In addition, the same code | symbol is attached | subjected to the component which is the same as that of Embodiment 2, or equivalent, and the detailed description is abbreviate | omitted.

In the present embodiment, as shown in FIG. 8, the charging circuit 22 of the capacitor 5 has a configuration in which a charging diode 11 is connected instead of the charging resistor 8 in the second embodiment.

With this configuration, it is possible to charge the capacitor 5 via the charging diode 11 in a steady state, and to prevent the capacitor 5 from being discharged when an accident occurs.

In the configurations of the fifth to sixth embodiments, it is necessary to control the opening of the charging opening / closing unit 10 when an accident occurs, but in the present embodiment, such control is not necessary. Therefore, as described in the fifth to sixth embodiments, when it is necessary to charge the capacitor 5 in a short time in a steady state, that is, even when having the duty of high-speed shutoff, the capacitor 5 is discharged at the time of occurrence of an accident. Without requiring control for prevention, it is possible to reliably form a current zero point and perform DC current interruption.

In the example illustrated in FIG. 8, the example in which the charging opening / closing unit 10 is connected instead of the charging resistor 8 is described with respect to the configuration of the second embodiment illustrated in FIG. 3. Similarly to the sixth embodiment, the present invention can be applied to the configurations of the first embodiment or the third to fourth embodiments.

As described above, according to the DC circuit breaker of the seventh embodiment, since the charging diode is connected instead of the charging resistor, it is necessary to charge the capacitor in a short time in a steady state. In this case, that is, even when having the duty of high-speed interruption, the current zero point can be reliably formed and the direct current interruption can be performed without requiring control for preventing discharge of the capacitor in the event of an accident.

Embodiment 8 FIG.
FIG. 9 is a diagram of a configuration example of the DC circuit breaker according to the eighth embodiment. In addition, the same code | symbol is attached | subjected to the component which is the same as that of Embodiment 2, or equivalent, and the detailed description is abbreviate | omitted.

In the present embodiment, as shown in FIG. 9, a plurality of blocking sections 2 in the second embodiment are connected in series, and voltage dividing resistors 12 are connected in parallel to each blocking section 2, respectively.

With this configuration, the overvoltage generated at both ends of the DC circuit breaker after the current interruption of the breaking unit 2 is divided by each voltage dividing resistor 12, and the voltage between the electrodes of each breaking unit 2 can be lowered. That is, it is possible to reduce the voltage duty per unit of each blocking unit 2.

In the example shown in FIG. 9, the example in which a plurality of blocking sections 2 in Embodiment 2 shown in FIG. 3 are connected in series has been described. However, for each configuration in Embodiment 1 or Embodiments 3 to 7 It is also possible to apply.

As described above, according to the DC circuit breaker of the eighth embodiment, since a plurality of circuit breakers are connected in series and a voltage dividing resistor is connected in parallel to each circuit breaker, the current interruption of the circuit breaker The overvoltage generated later at both ends of the DC circuit breaker can be shared by the plurality of circuit breakers, and the voltage duty per unit of each circuit breaker can be reduced.

Note that the configuration shown in the above embodiment is an example of the configuration of the present invention, and can be combined with another known technique, and a part thereof is omitted without departing from the gist of the present invention. Needless to say, it is possible to change the configuration.

DESCRIPTION OF SYMBOLS 1 DC line 2 Interrupting part 3 Disconnecting part 4 Commutation circuit 5 Capacitor 6 Reactor 7 Discharge gap 8 Charging resistor 9 Opening / closing part (first opening / closing part)
9a Opening and closing part (second opening and closing part)
DESCRIPTION OF SYMBOLS 10 Charging switch 11 Charging diode 12 Voltage dividing resistor 20 Series resonance circuit 21 Commutation switch unit 22 Charging circuit

Claims

A DC circuit breaker that forms a current zero point by superimposing a resonance current on a DC current flowing in a DC line, and interrupts the DC current at the current zero point,
A blocking portion inserted into the DC line and serving as a flow path for the DC current in a steady state;
A commutation circuit that commutates the direct current after opening the blocking unit;
With
The commutation circuit is
A series resonant circuit composed of a capacitor and a reactor;
A charging circuit for charging the capacitor with a DC potential of the DC line at a constant time;
After opening the blocking unit, the blocking unit and the series resonant circuit are connected in parallel, the resonant current generated by the series resonant circuit is superimposed on the DC current, and after the current blocking of the blocking unit, A commutation switch section for cutting a minute current flowing through the DC line via the series resonant circuit;
A DC circuit breaker comprising:
The commutation switch unit is
After opening of the interrupting part, a discharge gap that connects the interrupting part and the series resonant circuit in parallel;
After disconnecting the current of the interrupting part, a disconnecting part for cutting a minute current flowing in the DC line through the series resonant circuit;
The DC circuit breaker according to claim 1, comprising:
3. The DC circuit breaker according to claim 2, wherein the commutation switch unit is configured by connecting the disconnecting unit and the discharge gap in series.
The commutation switch unit is configured such that the disconnecting part is connected in series to the interrupting part, and the discharge gap is connected between a connection point of the interrupting part and the disconnecting part and the series resonance circuit. The DC circuit breaker according to claim 2, characterized in that:
The commutation switch unit has a function of connecting the blocking unit and the series resonant circuit in parallel after opening the blocking unit, and the DC line via the series resonant circuit after blocking the current of the blocking unit. 2. The DC circuit breaker according to claim 1, comprising a first opening / closing portion having a function of cutting a minute current flowing through the first current opening / closing portion.
The commutation switch unit is
A second opening / closing unit that connects the blocking unit and the series resonant circuit in parallel after the opening of the blocking unit;
After disconnecting the current of the interrupting part, a disconnecting part for cutting a minute current flowing in the DC line through the series resonant circuit;
The DC circuit breaker according to claim 1, comprising:
The DC commutator according to claim 6, wherein the commutation switch unit is configured such that the disconnecting unit and the second switching unit are connected in series.
The commutation switch unit is configured such that the disconnecting unit is connected in series to the blocking unit, and the second opening / closing unit is connected between the connecting point of the blocking unit and the disconnecting unit and the series resonance circuit. The DC circuit breaker according to claim 6, wherein:
The DC circuit breaker according to claim 1, wherein the charging circuit is a charging resistor.
The DC circuit breaker according to claim 1, wherein the charging circuit is a series circuit including a charging resistor and a charging switch.
The DC circuit breaker according to claim 1, wherein the charging circuit is a charging switch.
The DC circuit breaker according to claim 1, wherein the charging circuit is a charging diode.
2. The DC circuit breaker according to claim 1, wherein a plurality of the interrupting parts are connected in series, and voltage dividing resistors are connected in parallel to the interrupting parts, respectively.