JP3757726B2 - DC circuit breaker - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a commutation type DC circuit breaker that cuts off a direct current used for protection against ground faults and short circuits in electric railways, and more particularly, an overvoltage on the load side even if there is an open command from the outside during no load. The present invention relates to a DC circuit breaker that does not generate a fault.
[0002]
[Prior art]
FIG. 3 is a circuit diagram showing a configuration of the DC circuit breaker. The DC circuit breaker 5 includes a circuit breaker 1 including a vacuum valve, a commutation reactor 10 and a commutation capacitor 11 and a commutation switch 12 connected in series with each other, and a non-linear element 3 connected in parallel. The disconnection part 2 which consists of one vacuum valve is connected in series. The DC circuit breaker 5 is interposed between the DC power supply 4 and the load 6, but an LC filter in which a reactor 7 and a capacitor 8 are normally connected in series between the DC circuit breaker 5 and the load 6. 9 is interposed. The main circuit of the DC breaker 5 is provided with a DC current transformer 51 for detecting an accident current, and when the detected current is an accident current to be interrupted by receiving an output signal of the DC current transformer 51 An accident discriminating section 52 for outputting the accident cutoff command signal 23 is provided. Further, upon receiving the accident interruption command signal 23 and the open command signal 24 from the outside of the DC circuit breaker 5, the opening command signal 29 to the breaking unit 1 and the disconnecting unit 2 and the closing command signal 30 to the commutation switch 12. Is provided.
[0003]
In FIG. 3, the commutation capacitor 11 is always charged by a charging circuit (not shown), and the commutation switch 12 is turned on when the DC circuit breaker 5 performs the shut-off operation. It is injected into the blocking unit 1. As a result, a zero point is formed in the current flowing between the poles of the interrupting section 1, and the interrupting section 1 interrupts the current. The non-linear element 3 is for suppressing the overvoltage after being cut off. However, since the insulation resistance of the non-linear element 3 itself is lower than that of the vacuum valve, the cut-off part 1 is used to ensure insulation from the load 6 side. After disconnecting, the disconnecting portion 2 is also disconnected. The LC filter 9 is interposed in order to smooth the voltage waveform on the load 6 side.
[0004]
FIG. 4 is a time chart showing the operation timing of the interruption of the conventional DC circuit breaker. 4, an accident cutoff command is issued at time t _0. The waveform 13 of the accident cutoff command is that the accident cutoff command is issued when it rises, and the waveform 14 of the opening command is that that the opening command is issued to both the cutoff unit 1 and the disconnection unit 2 when it rises And Further, it is assumed that both the waveform 15 of the interrupting portion and the waveform 16 of the disconnecting portion 2 are opened when they fall. Further, it is assumed that the commutation switch waveform 17 is turned on when it rises. That is, an accident cutoff command is issued at time t ₀ as shown in waveform 13, and simultaneously, an opening command is issued to both cutoff unit 1 and disconnecting unit 2 as shown in waveform 14. Since the interrupting unit 1 is required to operate at high speed, an electromagnetic repulsive force or the like is usually applied, and the circuit breaker 1 is configured to be opened from time t ₀ to about 1 ms as shown by a waveform 15. On the other hand, the disconnecting portion 2 is driven only by the spring force and opens in about 20 ms as shown by the waveform 16. The commutation switch 12 is turned on when the distance between the poles of the interrupter 1 is opened as shown by the waveform 17, that is, after 2 to 3 ms from the time t _0, and a high-frequency current is injected into the interrupter 1. Thereby, when the combined current of the direct current and the high frequency current becomes zero, the interrupting unit 1 interrupts the current. On the other hand, the disconnecting portion 2 is recovered in insulation without injecting a high-frequency current because the inter-electrode current becomes minute as the interrupting portion 1 is interrupted.
[0005]
[Problems to be solved by the invention]
However, the conventional DC circuit breaker as described above has a problem that an overvoltage is generated between terminals on the load side when an open command is issued from the outside in a no-load state.
That is, the signal processing in the control unit 53 of the conventional DC circuit breaker 5 is such that the processing shown in the command signal system diagram of FIG. 5 is performed, and the accident cutoff command signal 23 and the open command signal from the outside. The output signal 29 of the OR circuit 25 is used as an opening command signal for both the blocking unit 1 and the disconnecting unit 2. Further, the output signal 29 of the OR circuit 25 is input to the control device 54, and after being delayed by 2 to 3 ms by a timer built in the control device 54, the output signal 30 is output. This output signal 30 is output from the commutation switch 12. Input command signal. For this reason, even when the open circuit signal 5 is opened in response to the open command signal 24 from the outside of the DC circuit breaker 5, the accident circuit break command is simply replaced with the open command from the outside in the time chart of FIG. However, when the circuit is opened in the no-load state, the current between the electrodes is so small that the circuit breaker 1 is opened and the insulation is recovered at the same time. Become. After that, since the commutation switch 12 is turned on, a voltage obtained by superimposing the power supply voltage and the charging voltage of the commutation capacitor 11 is generated between the terminals on the load 6 side until the disconnection unit 2 is disconnected. Therefore, when a filter is connected to the load 6 side, an overvoltage is applied to the filter. Conventionally, a filter that can withstand the duty exceeding the rated voltage in the circuit is used, resulting in an economical waste.
[0006]
An object of the present invention is to prevent an overvoltage from occurring on the load side.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, there is provided a commutation type DC circuit breaker for cutting off a direct current, wherein a parallel circuit of a cutoff unit and a nonlinear element is connected between a DC power source and a load. The interrupting portion is configured to open at a higher speed than the disconnection portion, and when interrupting an accident current, the poles of the interrupting portion are opened after a distance that can be interrupted to open the pole. A high-frequency current is injected in between, and the interrupting part is interrupted. After that , the disconnecting part is disconnected in about 20 ms , and the load side is already insulated by the disconnecting part even if there is an open command from outside when there is no load. A DC circuit breaker configured to prevent overvoltage from being generated between the terminals on the load side, the control device that outputs a signal by adjusting the timing of injecting the high-frequency current into the interrupting section, interrupts the accident current Case and no negative A first command for taking the logical sum of the shut-off command signal for shutting down the fault current and the external open command signal for opening in the no-load state. 1 and the output signal of the first OR circuit becomes an opening command signal for both the interrupting section and the disconnecting section, and the accident interrupting command signal further interrupts the accident current. The output signal of the control device is output after being delayed by 2 to 3 ms with a built-in timer, and the release command signal from the outside is also released in a no-load state. After being delayed by about 22 ms by a built-in timer, the output signal of the other control device is output, and the output signals of the control device and the other control device are output. The second OR circuit receiving the output signal of the control device that cuts off the fault current and the output signal of the other control device that opens in the no-load state, and the output signal of the second OR circuit Is a commutation switch input command signal, so that a high-frequency current is injected into the interrupting portion . As a result, even if the commutation switch is turned on and a high-frequency current is injected into the interrupting part, an overvoltage is not generated between the terminals on the load side because the disconnecting part is already insulated from the load side.
[0008]
Further, in such a configuration, the control device that adjusts the timing of injecting the high-frequency current into the interrupting unit and outputs a signal is provided with two types, that is, when the accident current is interrupted and when it is opened in a no-load state, The logical sum of the output signals from the control device may be taken, and a high-frequency current may be injected into the cutoff unit with the logical sum output signal. Thereby, it is possible to suppress an overvoltage that occurs when the circuit is opened in a no-load state without affecting the operation of the DC circuit breaker when interrupting an accident current.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on examples. FIG. 1 is a time chart showing the opening operation timing of the DC circuit breaker according to the embodiment of the present invention when there is no load. In FIG. 1, it is assumed that the DC circuit breaker 5 receives an open command signal 24 from the outside at time t ₀ . It is assumed that the DC breaker 5 receives an open command from the outside when the open command waveform 18 rises, and the open command waveform 19 is supplied to both the breaking unit 1 and the disconnecting unit 2 when the open command waveform 19 rises. Shall be issued. Moreover, both the waveform 20 of the interruption | blocking part 1 and the waveform 21 of the disconnection part 2 shall each be opened when it fell. Further, it is assumed that the commutation switch waveform 22 is turned on when it rises. That is, the DC circuit breaker 5 receives an open command from the outside at time t ₀ as shown in waveform 18, and at the same time, an opening command is issued to both the circuit breaker 1 and disconnecting unit 2 as shown in waveform 19. Since the interrupting unit 1 is required to operate at high speed, an electromagnetic repulsive force or the like is usually applied, and the blocking unit 1 is configured to be opened from time t ₀ to about 1 ms as shown by a waveform 20. On the other hand, the disconnecting portion 2 is driven only by a spring force and opens in about 20 ms as shown by the waveform 21. The commutation switch 12 is turned on after the disconnecting portion 2 is opened as shown by the waveform 22, that is, about 22 ms from the time t _0, and a high-frequency current is injected into the breaking portion 1. Thereby, since the load 6 side is already insulated by the disconnecting portion 2, no overvoltage is generated between the terminals on the load 6 side. For this reason, even if a filter such as an LC filter 9 is connected between the terminals on the load 6 side, no overvoltage is applied to the filter. Therefore, a filter having a rating suitable for the circuit voltage can be used. Can be economical. Note that the timing of the breaking operation when the fault current is flowing in the DC breaker 5 is the same as the conventional one, and is the same as the time chart of FIG.
[0010]
FIG. 2 is a command signal system diagram in the embodiment of FIG. The fault current cutoff command signal 23 and the external release command signal 24 are input to an OR circuit 25 for taking a logical sum, and an output signal 29 of the OR circuit 25 is supplied to both the cutoff unit 1 and the disconnection unit 2. Opening command signal. The accident cut-off command signal 23 is further input to the control device 26, and an output signal 26A is output after being delayed by 2 to 3 ms with a built-in timer. An open command signal 24 from the outside is also input to another control device 27, and an output signal 27A is output after being delayed by about 22 ms by a built-in timer. The OR circuit 28 receives the signals 26A and 27A, and the output signal 30 of the OR circuit 28 becomes the input command signal for the commutation switch 12. As a result, the overvoltage generated when the DC circuit breaker 5 is opened in a no-load state without affecting the operation of the DC circuit breaker 5 when interrupting an accident current can be suppressed. 5 itself will not cause any trouble.
[0011]
In the DC circuit breaker according to the above-described embodiment, when the normal load current is interrupted, the load current flows between the poles of the interrupter 1 unlike the case of opening in the no-load state. Since the insulation portion does not recover at the same time as the breaking portion 1 opens, even if the breaking operation is performed at the timing shown in FIG. However, when the normal load current is cut off, it is not necessary to cut off at high speed as in the case of turning off the accident current. In response to the opening command signal 24, the blocking operation may be performed according to the time chart of FIG.
[0012]
【The invention's effect】
As described above, in the case of opening in a no-load state, the present invention provides a filter connected to the load side by disconnecting the disconnecting portion and then injecting a high-frequency current into the interrupting portion. The one rated according to the circuit voltage can be used, and the economy is improved.
[0013]
Further, in such a configuration, the control device that adjusts the timing of injecting the high-frequency current into the interrupting unit and outputs a signal is provided with two types, that is, when the accident current is interrupted and when it is opened in a no-load state, A DC circuit breaker for interrupting an accident current by taking a logical sum of output signals from the control device and injecting a high-frequency current into the interrupting unit with the output signal of the logical sum The overvoltage generated when the circuit is opened in a no-load state without affecting the operation of the circuit can be suppressed, and the DC circuit breaker itself does not cause any trouble.
[Brief description of the drawings]
FIG. 1 is a time chart showing the opening operation timing of a DC circuit breaker according to an embodiment of the present invention when there is no load. FIG. 2 is a command signal system diagram in the embodiment of FIG. Circuit diagram [FIG. 4] Time chart showing the operation timing of a conventional DC circuit breaker [FIG. 5] Command signal system diagram in the conventional example of FIG.
1: interrupting unit, 2: disconnecting unit, 3: nonlinear element, 4: DC power supply, 5: DC circuit breaker, 6: load, 7: reactor, 8: capacitor, 9: LC filter, 10: commutation reactor, 11 : Commutation capacitor, 12: Commutation switch, 25, 28: OR circuit, 26, 27: Control device

Claims (1)

A commutation type DC circuit breaker for cutting off a direct current, wherein a parallel circuit of a breaking unit and a non-linear element is connected between a DC power source and a load via a disconnection unit, and the disconnection unit is connected to the disconnection unit When the accident current is cut off, the high frequency current is injected between the poles after the distance between the poles of the cut-off part is opened, and the cut-off part is cut off. After that , the disconnecting part is disconnected in about 20 ms, and even if there is an open command from the outside when there is no load, the disconnecting part already insulates the load side so that overvoltage does not occur between the terminals on the load side. A DC circuit breaker ,
The controller that adjusts the timing of injecting the high-frequency current into the interrupting section and outputs a signal is provided with two types of cases of interrupting the accident current and opening in a no-load state, and interrupts the accident current. And the open command signal from the outside in the case of opening in the no-load state are input to a first OR circuit for ORing, and the output signal of this first OR circuit is In addition to being an opening command signal for both the interrupting unit and the disconnecting unit, the accident interrupting command signal is also input to a control device that interrupts the accident current, and is delayed by 2 to 3 ms with a built-in timer. After that, the output signal of the control device is output, and the open command signal from the outside is also input to another control device that opens in a no-load state, and is delayed by about 22 ms with a built-in timer. The output signal of the other control device is output, and the second OR circuit receiving the output signal of the control device and the other control device outputs the output signal of the control device. And the output signal of the second control circuit that is opened in a no-load state, and the output signal of the second OR circuit becomes a commutation switch input command signal, whereby a high-frequency current is supplied to the interrupting unit. A direct current circuit breaker characterized in that is injected .

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