JP2014175077A - Current cutoff device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current cutoff device that does not need a charging circuit for charging a capacitor and allows reducing mechanical stress to the capacitor by charging the capacitor only when an accident occurs.SOLUTION: A current cutoff device 10 includes: a circuit breaker 1; a first switch 3 connected to a downstream-system-side terminal of the circuit breaker 1; and a current-limiting device 4 and a capacitor 6 each connected in parallel to the first switch 3. The current cutoff device 10 further includes: a second switch 5 disposed between a downstream-system-side terminal of the current-limiting device 4 and a downstream-system-side terminal of the capacitor 6; and a third switch 8 and a reactor 7 connected in series, disposed between an upstream-system-side terminal of the circuit breaker 1 and the downstream-system-side terminal of the capacitor 6.

Description

  The present invention relates to a current interrupting device, and in particular, for opening and closing a normal load current of a distribution system and for protecting a load-side equipment by interrupting a short-circuit current and a ground fault current at the time of an accident. The present invention relates to a current interruption device to be used.

  When an accident current occurs in the power system, the circuit breaker cannot be interrupted unless the current value becomes zero. Therefore, the circuit breaker interrupts the current at the timing when the accident current becomes zero.

  Therefore, in order to cut off the current, it is necessary to devise a method for forcibly setting the current value to zero when the current does not naturally reach the zero point such as a direct current. In addition, in the case of alternating current, the accident current is a sinusoidal waveform, so the timing when the current becomes zero comes at a fixed period, but in order to shut off early, there is a device to advance the timing when the current value becomes zero. Necessary.

  As a device for forcibly reducing the current to zero, for example, a current interrupting device disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2010-287460) includes a main switch, a sub-switch connected in series to the main switch, It has a commutation circuit composed of a capacitor, a commutation switch and a series circuit and connected in parallel to the main switch, and a capacitor charging device for charging the capacitor. The commutation circuit includes a commutation circuit forming switch provided on the opposite side of the commutation switch via a capacitor. When the main switch is closed, the commutation switch and the commutation circuit forming switch are opened, and the capacitor of the commutation circuit and the capacitor charging device can be disconnected from the main circuit.

  In the current interrupting device of Patent Document 1 as described above, when an accident occurs, a current having a polarity opposite to that of the accident current is supplied to the main switch as a circuit breaker, so that the accident current can be forcibly reduced to zero. Can be blocked.

  Further, the current interrupting device disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 60-65411) is formed by connecting a series circuit of a capacitor, a reactor and a closing means charged from a conducting path in parallel to a commutation breaker. The current interrupting device includes a thyristor provided in a capacitor charging circuit and connected in reverse parallel to pass only current in one direction, and an inversion control means for inverting the direction of the charging current to the capacitor.

JP 2010-287460 A JP 60-65411 A

  However, in the device of Patent Document 1, it is necessary to always charge a capacitor for generating a current opposite to the accident current in preparation for an accident whose occurrence time is unknown. Therefore, there is a problem that a charging circuit is required and the circuit configuration is complicated. Further, since a mechanical stress is always applied to a capacitor that is constantly charged, there is a problem that the service life of the capacitor is shortened.

  Also in the apparatus of Patent Document 2, it is necessary to provide a thyristor and an inversion control means, and the circuit configuration becomes complicated.

  Therefore, an object of the present invention is to provide a current interrupting device that does not require a charging circuit for charging a capacitor and can reduce mechanical stress on the capacitor by charging the capacitor only when an accident occurs. It is to be.

  In order to solve the above problems, a current interrupting device of the present invention includes a circuit breaker, a first switch connected to a downstream system side terminal of the circuit breaker, and each connected in parallel with the first switch Current limiting device and capacitor, second switch disposed between the downstream system side terminal of the current limiting device and the downstream system side terminal of the capacitor, the upstream system side terminal of the circuit breaker, and the downstream system of the capacitor A third switch and a reactor connected in series are arranged between the side terminals.

  According to the current interrupt device of the present invention, a charging circuit for charging a capacitor can be eliminated, and mechanical stress on the capacitor can be reduced by charging the capacitor only when an accident occurs. .

It is a figure showing the structure of the electric current interruption apparatus of Embodiment 1. FIG. It is a figure showing the example of the current waveform which flows into a circuit breaker. (A) is a figure showing the state of the electric current interruption apparatus 10 in the period of (1) of FIG. 2, (b) is the state of the electric current interruption apparatus 10 in the period of (2) and (3) of FIG. (C) is a figure showing the state of the electric current interruption apparatus 10 in the period of (4) of FIG. It is a figure showing the structure of the electric current interruption apparatus of Embodiment 2. FIG. FIG. 5 is a diagram illustrating a configuration of a current interrupt device of a third embodiment. (A) is a figure showing the state of the electric current interruption apparatus 30 in the period of (1) of FIG. 2, (b) is the state of the electric current interruption apparatus 30 in the period of (2) and (3) of FIG. (C) is a figure showing the state of the electric current interruption apparatus 30 in the period of (4) of FIG. 2, (d) is the electric current interruption apparatus in the time after the time of FIG. It is a figure showing the state of 30.

[Embodiment 1]
(Constitution)
FIG. 1 is a diagram illustrating the configuration of the current interrupt device according to the first embodiment. FIG. 1 shows a steady state in which no fault current flows through the current interrupt device 10. As shown in FIG. 1, the current interrupting device 10 includes a circuit breaker 1, a first switch 3, a current limiting device 4, a second switch 5, a capacitor 6, a reactor 7, 3 switches 8.

The first switch 3 is connected to the downstream system side terminal of the circuit breaker 1.
The current limiting device 4 and the capacitor 6 are connected in parallel with the first switch 3. The current limiting device 4 has a function of generating an impedance by an energizing current and suppressing the current.

  The second switch 5 is disposed between the downstream system side terminal of the current limiting device 4 and the downstream system side terminal of the capacitor 6.

  The third switch 8 and the reactor 7 are arranged between the upstream system side terminal of the circuit breaker 1 and the downstream system side terminal of the capacitor 6.

  At the steady state, as shown in FIG. 1, the circuit breaker 1 and the first switch 3 are closed, and the second switch 5 and the third switch 8 are opened. The internal resistance at the time of closing of the circuit breaker 1 and the first switch 3 through which a current flows in a steady state is relatively larger than the internal resistance of the current limiting device 4 connected in parallel to the first switch 3. It is set small. As a result, in a steady state, the current flows through the first switch 3 without substantially flowing through the current limiting device 4.

(Operation)
FIG. 2 is a diagram illustrating an example of a waveform of a current flowing through the circuit breaker 1. 3A is a diagram showing the state of the current interrupt device 10 during the period (1) in FIG. 2, and FIG. 3B is a current interrupt during the periods (2) and (3) in FIG. It is a figure showing the state of the apparatus 10, FIG.3 (c) is a figure showing the state of the electric current interruption apparatus 10 in the period of (4) of FIG.

  Next, the operation of the current interrupting device 10 will be described with reference to FIGS. 2 and 3A to 3C.

  In the steady state, as shown in FIG. 3A, the circuit breaker 1 and the first switch 3 are closed, and the second switch 5 and the third switch 8 are opened. Yes.

  When a ground fault occurs on the downstream system side of the current interrupt device 10 at time T0, an accident current flows, and thus the current flowing through the current interrupt device 10 starts to increase.

  When a current detection device (not shown) detects that the value of the current flowing through the current breaker 10 has reached a set threshold value I0 at time T1, the current detector is opened to the breaker 1 and the first switch 3. A pole command signal is transmitted, and a closing command signal is transmitted to the second switch 5. As a result, as shown in FIG. 3B, the circuit breaker 1 and the first switch 3 are quickly opened, and the second switch 5 is quickly closed.

  When the first switch 3 is opened, the current passing through the circuit breaker 1 flows to the current limiting device 4. When the current limiting device 4 is energized, the potential between the terminals of the current limiting device 4 rises and is connected in parallel to the current limiting device 4 because the downstream system side is at ground potential due to a ground fault. The capacitor 6 is charged.

  When the voltage between the terminals of the current limiting device 4 rises to the same value as the system voltage at time T2, the fault current starts to limit current. The voltage between the terminals of the current limiting device 4 continues to rise to the set value thereafter.

  When a current detection device (not shown) detects that the fault current is limited to a predetermined current value I1 by the current limiting device 4 at time T3, the current detection device sends an opening command signal to the second switch 5. In addition to transmitting, a closing command signal is transmitted to the third switch 8. As a result, as shown in FIG. 3C, the second switch 5 is quickly opened, the electric circuit between the current limiting device 4 and the capacitor 6 is disconnected, and the third switch 8 is closed. . As a result, a closed circuit is formed between the capacitor 6, the circuit breaker 1, the third switch 8, and the reactor 7, and the electric charge accumulated in the capacitor 6 causes the circuit breaker 1 to have an opposite polarity to the accident current. Current flows. A current zero point is formed by superimposing the reverse polarity current and the accident current.

  When the current supplied to the circuit breaker 1 forms a zero point at time T4, the circuit breaker 1 disappears and is interrupted.

  As described above, according to the current interrupt device of the first embodiment, the charging circuit for charging the capacitor is not necessary, and the capacitor is charged only when the current is interrupted, so that the mechanical stress of the capacitor can be reduced.

  Further, according to the present embodiment, it is possible to form a current zero point when the DC current is interrupted, and it is possible to shorten the interruption time by forming a zero point earlier than the original current zero point when interrupting the AC current.

[Embodiment 2]
FIG. 4 is a diagram illustrating the configuration of the current interrupt device according to the second embodiment. FIG. 4 shows a steady state in which no accident current flows.

  In FIG. 4, the same parts as those in the first embodiment shown in FIG. 1 are denoted by the same names, and description thereof is not repeated. The circuit breaker 21 included in the current interrupting device 20 of FIG. 4 includes an interrupting switch 22 excellent in current interrupting means and an insulating switch 23 excellent in insulating means.

  As the breaker switch 22 excellent in current interrupting means, for example, a vacuum breaker that generates an arc in a vacuum and interrupts the current can be used.

  For example, an SF6 gas switch can be used as the insulating switch 23 having excellent insulating means. The use of a vacuum circuit breaker and a gas switch in series has been conventionally known. For example, Japanese Patent Publication No. 40-6658 discloses the structure thereof. The vacuum circuit breaker has a high large current interrupting performance regardless of the current change rate (di / dT) immediately before the current interrupting. On the other hand, the gas switch has high interelectrode insulation recovery characteristics.

  Therefore, by configuring the circuit breaker 21 with the circuit breaker 22 and the circuit breaker 23 connected in series with the circuit breaker 21, regardless of the current change rate (di / dT) immediately before the current to be interrupted, High voltage and large current can be cut off.

  As described above, according to the current interrupting device according to the second embodiment, the rate of change di / dt of the oscillating current passed from the capacitor and the reactor to the circuit breaker is steep, and the recovery voltage applied to the circuit breaker after the current is interrupted Even when the current is high, the accident current can be reliably interrupted.

[Embodiment 3]
In the first and second embodiments, when the fault current is interrupted, the disconnector installed outside the upstream system side terminal of the current interrupter (not shown) opens to disconnect the accident circuit from the system. As a result, after the current interruption, the capacitor 6 is maintained with the electric charge remaining. Therefore, it is necessary to discharge the capacitor 6 in preparation for the next current interruption. The present embodiment has a mechanism for discharging the electric charge of the capacitor 6.

(Constitution)
FIG. 5 is a diagram illustrating the configuration of the current interrupt device of the third embodiment. FIG. 5 shows a state immediately after current interruption. In FIG. 5, the same parts as those of the first embodiment in FIG. 1 are denoted by the same names, and description thereof will not be repeated. In addition to the components included in the current interrupt device 10 of FIG. 1, the current interrupt device 30 of FIG. 5 includes a fourth switch 32, a circuit switch 31, a discharge resistor for discharging the residual charge of the capacitor 6. 33.

  The circuit switch 31 has a terminal A, a terminal B, and a terminal C. The terminal A is connected to the downstream system side terminal of the circuit breaker 1. The terminal B is connected to the upstream system side terminal of the capacitor 6. Terminal C is connected to ground. The circuit switch 31 switches the connection destination of the terminal B to either the terminal A or the terminal C. That is, the circuit switch 31 switches the connection destination of the upstream system side terminal of the capacitor 6 to the downstream system side terminal of the circuit breaker 1 or the ground.

  The fourth switch 32 and the discharge resistor 33 connected in series are connected in parallel with the first switch 3, the current limiting device 4, and the capacitor 6. The upstream system side terminal of the fourth switch 32 and the discharge resistor 33 arranged on the upstream system side (discharge resistor 33 in the case of FIG. 5) is connected to the ground.

(Operation)
6A is a diagram illustrating the state of the current interrupt device 30 during the period (1) in FIG. 2, and FIG. 6B is a current interrupt during the periods (2) and (3) in FIG. 6 is a diagram showing the state of the device 30, FIG. 6C is a diagram showing the state of the current interrupt device 30 during the period (4) in FIG. 2, and FIG. It is a figure showing the state of the electric current interruption apparatus 30 in the later time.

  Next, the operation of the current interrupt device 30 will be described with reference to FIGS. 2 and 6A to 6D.

  In the steady state, as shown in FIG. 6A, the circuit breaker 1 and the first switch 3 are closed, and the second switch 5 and the third switch 8 are opened. Yes. The fourth switch 32 is open, and the terminal A and the terminal B of the circuit switch 31 are connected.

  When a ground fault occurs on the downstream system side of the current interrupt device 30 at time T0, an accident current flows, and thus the current flowing through the current interrupt device 10 starts to increase.

  When a current detection device (not shown) detects that the value of the current flowing through the current interruption device 30 has reached a set threshold value I0 at time T1, the control device (not shown) causes the circuit breaker 1 and the first switch 3 to In addition to transmitting an opening command signal, a closing command signal is transmitted to the second switch 5. As a result, as shown in FIG. 6B, the circuit breaker 1 and the first switch 3 are quickly opened, and the second switch 5 is quickly closed.

  When the first switch 3 is opened, the current passing through the circuit breaker 1 flows to the current limiting device 4. When the current limiting device 4 is energized, the potential between the terminals of the current limiting device 4 rises and is connected in parallel to the current limiting device 4 because the downstream system side is at ground potential due to a ground fault. The capacitor 6 is charged.

  When the voltage between the terminals of the current limiting device 4 rises to the same value as the system voltage at time T2, the fault current starts to limit current. The voltage between the terminals of the current limiting device 4 continues to rise to the set value thereafter.

  When a current detection device (not shown) detects that the fault current is limited to a predetermined current value I1 by the current limiting device 4 at time T3, the control device (not shown) sends an opening command signal to the second switch 5. And a closing command signal to the third switch 8. As a result, as shown in FIG. 6C, the second switch 5 is quickly opened, the electric circuit between the current limiting device 4 and the capacitor 6 is disconnected, and the third switch 8 is closed. . As a result, a closed circuit is formed between the capacitor 6, the circuit breaker 1, the third switch 8, and the reactor 7, and the electric charge accumulated in the capacitor 6 causes the circuit breaker 1 to have an opposite polarity to the accident current. Current flows. A current zero point is formed by superimposing the reverse polarity current and the accident current.

  When the current supplied to the circuit breaker 1 forms a zero point at time T4, the circuit breaker 1 disappears and is interrupted.

  Thereafter, when a disconnector (not shown) on the upstream system side of the current interrupting device 30 is opened and the fault line is disconnected from the system, the controller (not shown) is connected to the circuit switch 31 as shown in FIG. Terminal B and terminal C are connected. As a result, the capacitor 6 is connected to the ground. Thereafter, the control device transmits a closing command signal to the fourth switch 32, and the fourth switch 32 is closed. As a result, the residual charge of the capacitor 6 is discharged with a time constant determined by the product of the capacitor of the capacitor 6 and the resistance value of the discharge resistor 33, and the capacitor 6 enters a non-charged state. Here, the same effect can be obtained even if the connection order of the terminal B of the circuit switch 31 to the terminal C and the closing order of the fourth switch 32 are reversed.

  After the capacitor 6 is brought into a non-charged state by the operation of the circuit switch 31 and the fourth switch 32, the control device (not shown) closes the circuit breaker 1 and closes the first switch 3. The second switch 5 is opened, the third switch 8 is opened, the fourth switch 32 is opened, and the terminals A and B of the circuit switch 31 are connected to cut off the current. The device 30 is returned to the initial state to prepare for the next current interruption.

  As described above, according to the current interrupt device of the third embodiment, after the current is interrupted, the charge charged in the capacitor can be discharged in preparation for the next current interrupt.

(Modification)
In addition, the current interrupt device 30 must be inspected at a constant cycle. In the inspection of the capacitor 6 performed at that time, the fourth switch 32, the circuit switch 31, and the discharge resistor 33 are used. Also good.

  Since the capacitor 6 is connected in parallel with the first switch 3 at a constant time, the capacitor 6 is in a charged state although it is slightly due to the voltage drop caused by the first switch 3. If the capacitor 6 is inadvertently inspected in this state, there is a risk that an operator may get an electric shock. Therefore, the capacitor 6 must be completely uncharged during the inspection.

  Therefore, when inspecting the current interrupt device 30, the disconnector (not shown) installed outside both terminals of the current interrupt device 30 is opened to disconnect the current interrupt device from the system, and as described in the third embodiment. In addition, a control device (not shown) connects the terminal B and the terminal C of the circuit switch 31 as shown in FIG. As a result, the capacitor 6 is connected to the ground. Thereafter, the control device transmits a closing command signal to the fourth switch 32, and the fourth switch 32 is closed. As a result, the residual charge of the capacitor 6 is discharged with a time constant determined by the product of the capacitor of the capacitor 6 and the resistance value of the discharge resistor 33, and the capacitor 6 enters a non-charged state. Here, the same effect can be obtained even if the connection order of the terminal B of the circuit switch 31 to the terminal C and the closing order of the fourth switch 32 are reversed.

  As described above, in this modification, the capacitor 6 is brought into a non-charged state when the current interrupting device 30 is inspected, so that the capacitor can be inspected safely.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1,21 Circuit breaker, 3 First switch, 4 Current limiting device, 5 Second switch, 6 Capacitor, 7 Reactor, 8 3rd switch, 10, 20, 30 Circuit breaker, 22 Circuit breaker 23, switch for insulation, 31 circuit switcher, 32 4th switch, 33 discharge resistance.

Claims (5)

A circuit breaker,
A first switch connected to a downstream system side terminal of the circuit breaker;
A current limiting device and a capacitor, each connected in parallel with the first switch;
A second switch disposed between the downstream system side terminal of the current limiting device and the downstream system side terminal of the capacitor;
A current interrupting device comprising a third switch and a reactor connected in series arranged between an upstream system side terminal of the circuit breaker and a downstream system side terminal of the capacitor. When it is detected that the current flowing through the circuit breaker has increased to a predetermined value due to an accident, the circuit breaker and the first switch are opened and the second switch is closed,
The second switch opens and the third switch closes when it is detected that the current flowing through the circuit breaker is limited to a predetermined value thereafter. Current interrupt device. A circuit switcher for switching the connection destination of the upstream system side terminal of the capacitor to the downstream system side terminal of the circuit breaker or the ground;
A fourth switch and a discharge resistor connected in parallel with the capacitor, and an upstream system side terminal of the fourth switch and the discharge resistor arranged on the upstream system side is a ground The current interrupting device according to claim 2 to be connected.   The circuit switch connects the upstream system side terminal of the capacitor and the ground at the time of the regular inspection of the capacitor or after the break of the breaker is completed, and the fourth switch is closed. The current interruption device according to claim 3.   The current breaker according to any one of claims 1 to 4, wherein the breaker includes a vacuum breaker and a gas switch connected in series.

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