JP2010238391A - DC circuit breaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To alleviate overvoltage added on an electrical apparatus constituting a commutation circuit, at the current interruption of a direct-current circuit. <P>SOLUTION: The direct-current breaker is provided with a sub breaker 2 connected to a power source side of a direct-current circuit for opening the direct-current circuit; a main breaker 1 for breaking current of a direct-current circuit connected in series with the sub breaker 2; an energy-absorbing element 3 connected in parallel with the main breaker 1; and a commutation circuit 4 connected in parallel with the main breaker 1. The commutation circuit 4 has its commutation switch 5, connected to a power source side, and to the commutation switch 5, a first reactor 6 and a first commutation capacitor 6 are connected, in series. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a DC circuit breaker that can reduce an overvoltage applied to a commutation circuit when the DC circuit is interrupted.

  2. Description of the Related Art Conventionally, in a DC circuit such as an electric railway feeder circuit, a DC circuit breaker is provided on the power source side to cut off an energization current or an accident current.

  In this type of DC circuit breaker, as shown in FIG. 4, a main circuit breaker 1 is provided on the power source side, and a sub circuit breaker 2 is connected in series on the load side. An energy absorbing element 3 and a commutation circuit 4 are connected to the main circuit breaker 1 in parallel. In the commutation circuit 4, a commutation switch 5, a first reactor 6, and a first commutation capacitor 7 are connected in series.

  The first commutation capacitor 7 is charged by a charging device (not shown) such that when a current flows from the power supply side to the load side, the load side terminal becomes positive. When interrupting the current, the main circuit breaker 1 and the sub circuit breaker 2 are opened, the commutation switch 5 is closed, the first commutation capacitor 7 is discharged, and the current flowing in the main circuit breaker 1 is reversed. Is interrupted at the current zero point. When current interruption is performed by the main circuit breaker 1, the overvoltage is absorbed by the energy absorption element 3, the current is attenuated, and the interruption is completed (see, for example, Patent Document 1).

  At this time, between the terminals of the energy absorption element 3, a cutoff overvoltage Va that jumps higher than the power supply voltage V 0 is applied. Then, as shown in the drawing, the first commutation capacitor 7 is charged on the power source side with a positive polarity. For this reason, V0 + Va is applied between the ground of the device between the commutation switch 5 and the first commutation capacitor 7. The cutoff overvoltage Va is larger than the power supply voltage V0 and may be several times as large.

  On the other hand, in order to control the magnitude of the commutation current, a second reactor 8 and a second commutation capacitor 9 are provided between the first reactor 6 and the first commutation capacitor 7 as shown in FIG. Are connected in series, and a commutation circuit 4 in which a changeover switch 10 is connected in parallel to this circuit is known (see, for example, Patent Document 2).

  Even in such a commutation circuit 4, the first commutation capacitor 7 is applied with a cut-off overvoltage Va having a positive polarity on the power supply side when the current is cut off. For this reason, V0 + Va is applied between the ground of the device between the commutation switch 5 and the first commutation capacitor 7.

JP-A-5-234471 (2-3 pages, FIG. 1) Japanese Patent Laying-Open No. 2005-222705 (pages 4-5, FIG. 2)

  In the above-described conventional DC circuit breaker, when the commutation circuit 4 is operated at the time of interrupting the current of the DC circuit, an overvoltage obtained by adding the operation voltage V0 and the interruption overvoltage Va is added to the devices constituting the commutation circuit 4. was there. For this reason, it has been desired to reduce the overvoltage applied to the commutation circuit 4.

  The present invention has been made to solve the above problem, and an object of the present invention is to provide a DC circuit breaker that can reduce an overvoltage applied to devices constituting a commutation circuit when a current is interrupted.

  In order to achieve the above object, a DC circuit breaker according to the present invention is connected to a sub circuit breaker connected to a power supply side of a DC circuit, a main circuit breaker connected in series to the sub circuit breaker, and connected to the main circuit breaker in parallel. An energy absorbing element and a commutation circuit connected in parallel to the main circuit breaker, wherein the commutation circuit connects a commutation switch to a power supply side, and the commutation switch includes a first reactor and a first A commutation capacitor is connected in series.

  According to the present invention, since the secondary circuit breaker is connected to the power supply side from the commutation switch, the power supply side is opened by the secondary circuit breaker in the commutation circuit at the time of current interruption, and the overvoltage can be reduced. .

The circuit diagram which shows the circuit structure of the direct-current circuit breaker which concerns on Example 1 of this invention. The circuit diagram which shows the circuit structure of the direct-current circuit breaker which concerns on Example 2 of this invention. The circuit diagram which shows the circuit structure of the direct-current circuit breaker which concerns on Example 3 of this invention. The circuit diagram which shows the circuit structure of the conventional DC circuit breaker. The circuit diagram which shows the circuit structure of the conventional DC circuit breaker.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, a DC circuit breaker according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a circuit diagram showing a circuit configuration of a DC circuit breaker according to Embodiment 1 of the present invention. In FIG. 1, the same components as those in the prior art are denoted by the same reference numerals.

  As shown in FIG. 1, a secondary circuit breaker 2 is provided on the power supply side, and a main circuit breaker 1 is connected in series on the load side. An energy absorbing element 3 and a commutation circuit 4 are connected to the main circuit breaker 1 in parallel. In the commutation circuit 4, a commutation switch 5, a first reactor 6, and a first commutation capacitor 7 are sequentially connected in series from the power supply side to the load side.

  As in the conventional case, the first commutation capacitor 7 is charged by a charging device (not shown) so that the load-side terminal has a positive polarity when a current flows from the power supply side to the load side. When interrupting the current, the main circuit breaker 1 and the sub circuit breaker 2 are opened, the commutation switch 5 is closed, the first commutation capacitor 7 is discharged, and the current flowing in the main circuit breaker 1 is reversed. Superimpose the commutation current and cut off at the current zero point. When current interruption is performed by the main circuit breaker 1, the overvoltage is absorbed by the energy absorption element 3, the current is attenuated, and the DC circuit is opened by the sub circuit breaker 2.

  At this time, between the terminals of the energy absorbing element 3, a cutoff overvoltage Va jumped from the power supply voltage V 0 is applied as in the conventional case. Then, as shown in the drawing, the first commutation capacitor 7 is charged on the power source side with a positive polarity. However, since the auxiliary circuit breaker 2 is opened, the operating voltage V0 is not applied between the commutation switch 5 and the first commutation capacitor 7 to the ground of the device, and only the overvoltage Va is applied. This is lower than the conventional overvoltage V0 + Va, and the overvoltage can be reduced.

  Here, the power supply side terminal of the first commutation capacitor 7 has a smaller cross-sectional area than the load side terminal. This is because the overvoltage Va is a steep wave and the charged time value is suppressed by lengthening the time constant during charging. The load side terminal has a large cross-sectional area and can inject a predetermined commutation current into the main circuit breaker 1.

  According to the DC circuit breaker of the first embodiment, the secondary circuit breaker 2 is connected to the power source side of the DC circuit, and the commutation switch 5 is connected to the power source side of the commutation circuit 4, so The power source side is opened by the capacitor 2, and only the cut-off overvoltage Va absorbed by the energy absorbing element 3 is applied to the commutation circuit 4, and the overvoltage can be reduced.

  In the first embodiment, the commutation circuit 4 is connected in the order of the commutation switch 5, the first reactor 6, and the first commutation capacitor 7, but the first reactor 6 and the first commutation capacitor 7 are connected. Even if the connection order is reversed, the overvoltage applied between the commutation switch 5 and the first commutation capacitor 7 can be reduced. Further, if the first reactor 6 is connected to the power supply side with respect to the commutation switch 5, the voltage applied between the ground of the first reactor 6 can be made almost zero.

  Next, a DC circuit breaker according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 2 is a circuit diagram illustrating a circuit configuration of the DC circuit breaker according to the second embodiment of the present invention. The second embodiment differs from the first embodiment in the connection position of the auxiliary circuit breaker. In FIG. 2, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 2, the auxiliary circuit breaker 2 and the energy absorption element 3 connected in series are connected in parallel with the main circuit breaker 1, and the commutation circuit 4 is connected in parallel to the energy absorption element 3. Thereby, the energy absorption element 3 and the commutation circuit 4 can be separated from the power supply side by the auxiliary circuit breaker 2 when the current is interrupted.

  According to the DC circuit breaker of the second embodiment, in addition to the effects of the first embodiment, since only the main circuit breaker 1 is connected to the DC circuit, the DC circuit resistance can be reduced. Further, the main circuit current is not passed through the auxiliary circuit breaker 2, and the current carrying capacity can be reduced.

  Next, a DC circuit breaker according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 3 is a circuit diagram showing a circuit configuration of a DC circuit breaker according to Embodiment 3 of the present invention. The third embodiment differs from the first embodiment in the configuration of the commutation circuit. In FIG. 3, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 3, in the commutation circuit 4, a second reactor 8 and a second commutation capacitor 9 are connected in series between the commutation switch 5 and the first reactor 6, and switched to these circuits. The switch 10 is connected in parallel. The second reactor 8 and the second commutation capacitor 9 are used for controlling the magnitude of the commutation current.

  Here, since the magnitude of the commutation current is controlled by the circuit configured by the second reactor 8, the second commutation capacitor 9, and the changeover switch 10, this is defined as a commutation current control circuit.

  According to the DC circuit breaker of the third embodiment, in addition to the effects of the first embodiment, the second reactor 8 and the second commutation capacitor 9 are connected in order to control the magnitude of the commutation current. Also in the flow circuit 4, only the cut-off overvoltage Va absorbed by the energy absorbing element 3 is applied between the ground between the commutation switch 5 and the first commutation capacitor 7, thereby reducing the overvoltage. it can.

  In the third embodiment, the commutation current control circuit is connected between the commutation switch 5 and the first reactor 6, but the first reactor 6 and the first commutation capacitor 7, or the first Even if a commutation current control circuit is connected between the commutation capacitor 7 and the load side terminal, the overvoltage applied to the commutation circuit 4 can be reduced.

DESCRIPTION OF SYMBOLS 1 Main circuit breaker 2 Sub circuit breaker 3 Energy absorption element 4 Commutation circuit 5 Commutation switch 6 1st reactor 7 1st capacitor 8 2nd reactor 9 2nd capacitor 10 Changeover switch

Claims (4)

A secondary circuit breaker connected to the power supply side of the DC circuit;
A main circuit breaker connected in series to the sub circuit breaker;
An energy absorbing element connected in parallel to the main circuit breaker;
A commutation circuit connected in parallel to the main circuit breaker,
In the commutation circuit, a commutation switch is connected to a power source side, and a first reactor and a first commutation capacitor are connected in series to the commutation switch. The main circuit breaker connected to the DC circuit is connected in parallel with the secondary circuit breaker connected in series and the energy absorption element,
A DC circuit breaker in which a commutation circuit is connected in parallel to the energy absorbing element,
The commutation circuit includes a commutation switch connected to a power supply side, and a first reactor and a first commutation capacitor connected in series.   The DC circuit breaker according to claim 1 or 2, wherein a commutation current control circuit is connected to the commutation circuit.   4. The DC circuit breaker according to claim 3, wherein the commutation current control circuit includes a changeover switch connected in parallel to a circuit in which a second capacitor and a second reactor are connected in series.

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