JPH11265644A - Switching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switching device using a semiconductor switch with small capacity without reducing the time responsiveness performance of input and cutoff by reducing the withstand current capacity of the semiconductor switch. SOLUTION: This device is formed of a thyristor 1A, a resistor 10 connected in series to the thyristor 1A, and a mechanical switch 2A connected in parallel to the serial circuit. The mechanical switch 2A is openable at high speed by an electromagnetic repelling mechanism. The current-limiting element is a reactor or the resistor 10, and it is a nonlinear current-limiting element having a nonlinear resistance value to passing current value. The semiconductor switch is formed of a pair of reversely juxtaposed thyristors 1A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switchgear such as a circuit breaker or a switchgear used in a power distribution system, and more particularly to a switchgear having a reduced response time when being turned on or cut off.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing a conventional switchgear in which a thyristor and a mechanical switch described in Japanese Patent Application No. 8-40044 are connected in parallel. In the figure, 1
Is a thyristor (semiconductor switch), 2 is a mechanical switch,
3 is a control unit of the switchgear, 4 is a snubber circuit of a thyristor, 5 is an arrester for thyristor protection for protecting the thyristor 1 from overvoltage, 6 is a saturable reactor for protecting the thyristor 1 from surge current, and 7 is a saturable reactor. 8 is a switchgear connected in series with the switchgear.

Next, the operation will be described. Since the disconnector 7 connected in series with the switchgear 8 is not directly related to the present invention, the disconnector will always be in a closed state in the following, and a description thereof will be omitted. A description will be given of an operation from when the switchgear 8 is in the open state, that is, when the two thyristors 1 are both non-conductive and the mechanical switch 2 is in the open state, and when the switchgear 8 is in the closed state.

When a closing command is input to the control unit 3 of the switching device 8, first, a firing signal is input from the control unit 3 to the thyristor 1 via the control line 3b, and the thyristor 1 is turned on. Thus the current I ₁ flows through the circuit. If this current is a steady state current, the mechanical switch 2 is subsequently turned on by the control unit 3 via the control line 3a. In general for the resistance in the closed state of the mechanical switch 2 smaller than the resistance thyristors 1, most of the steady-state current flows through the mechanical switch 2 as the current I _2. After the mechanical switch 2 is turned on, the firing signal of the thyristor 1 is stopped. When the current I ₃ flowing when the thyristor 1 is fired is the fault current, that is, when the fault circuit is turned on, the firing signal to the thyristor 1 is stopped without turning on the mechanical switch 2,
The current is interrupted by thyristor 1.

Next, the operation for interrupting the current will be described. Before the current interruption, the electric current I ₂ flows through the mechanical switch 2. When a shutoff command is input to the control unit 3 from the outside, the control unit 3 sends an opening command to the mechanical switch 2 via a control line 3a, and sends an ignition signal to the thyristor 1 via a control line 3b. Is sent. This opening command causes the mechanical switch 2 to open, and an arc is generated between the contacts of the mechanical switch 2. Resistance of arc current flowing to the mechanical switch 2 larger than the resistance of the thyristor 1 is commutated as a current I ₃ to the thyristor 1.

As a result, the arc between the contacts of the mechanical switch 2 is extinguished, and the entire current flows through the thyristor 1. After the total current flows through the thyristor 1, firing signal from the control unit 3 to the thyristor 1 is stopped, thyristor 1 interrupts the current I _3. If the mechanical switch 2 is capable of high-speed operation with a short opening time, current can be interrupted instantaneously without impairing the high-speed response characteristics of the thyristor 1.

[0007]

By the way, since the conventional switchgear is constructed and operates as described above, a large current equivalent to a short-circuit current flows through the thyristor when an accident current such as a short circuit is interrupted and when an accident circuit is turned on. . For this reason, the thyristor needs a current withstand capability corresponding to the short-circuit current, and has a problem that it becomes large and expensive. The present invention has been made in order to solve the above-mentioned problems, and has a switching device using a semiconductor switch such as a thyristor and a mechanical switch together with a low-cost thyristor to reduce the current withstand capability required by the thyristor. The purpose is to get.

[0008]

According to a first aspect of the present invention, there is provided a switchgear comprising: a semiconductor switch; a current limiting element connected in series to the semiconductor switch to suppress a fault current; A mechanical switch having a pair of contactable and detachable contacts connected in parallel to a circuit in which the flow elements are connected in series, wherein the switch is turned on by the semiconductor switch, and the cutoff is cut off by the mechanical switch. Things.

According to a second aspect of the present invention, in the first aspect of the present invention, the mechanical switch is capable of high-speed opening by an electromagnetic repulsion mechanism.

[0010] According to a third aspect of the present invention, in the switchgear according to the first aspect, the current limiting element is a reactor.

According to a fourth aspect of the present invention, in the switchgear according to the first aspect, the current limiting element is a resistor.

According to a fifth aspect of the present invention, in the switchgear according to the first aspect, the current limiting element is a nonlinear current limiting element having a non-linear resistance with respect to a passing current value. It is.

According to a sixth aspect of the present invention, there is provided a switchgear according to any one of the first to fifth aspects.
The semiconductor switch is constituted by a pair of thyristors which are antiparallel to each other.

According to a seventh aspect of the present invention, there is provided a switchgear according to any one of the first to sixth aspects.
Detecting means for detecting a current flowing when the semiconductor switch is turned on, and a determination unit for determining whether the detected value is a fault current or a steady current, wherein the current flowing when the semiconductor switch is turned on is a fault current or a steady current; And controls the closing of the mechanical switch.

According to an eighth aspect of the present invention, in the switching device according to the seventh aspect of the present invention, when the current flowing when the semiconductor switch is turned on is an accidental current, the mechanical switch is turned on. Instead, the semiconductor switch is controlled so as to immediately cut off the fault current.

According to a ninth aspect of the present invention, in the switching device according to the seventh or the eighth aspect, when the current flowing when the semiconductor switch is turned on is a steady current, the mechanical switching is performed. It controls so that the container is put in immediately.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a configuration diagram showing Embodiment 1 of the present invention. 1, parts corresponding to those in FIG. 7 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the figure,
1A is a thyristor as a semiconductor switch which is connected in the opposite direction to each other and has a configuration capable of flowing current in both directions.
A is a mechanical switch capable of high-speed driving, 3A is a control unit that sends opening and closing commands to the thyristor 1A and the mechanical switch 2A, 8A is the switching device according to the present embodiment, and 10 is a current suppressing device. Is a current detector for detecting a current flowing through the switchgear 8A.

FIG. 2 shows a mechanical switch which can be driven at high speed using electromagnetic repulsion and which can be used as the switch of FIG. In the figure, 21 and 22 are terminals, 23 is a vacuum valve for opening and closing an electric circuit, 24 is a contact installed in the vacuum valve, 25 is an electric circuit formed by the terminals 21 and 22 and the vacuum valve 23 and a mechanical valve. An insulator for insulating the mechanical part of the switch 2A, 26 is a repulsion disk, 27 is an opening coil for applying an electromagnetic force in the opening direction to the repulsion disk 26 when the contact 24 is opened. , 28 are the rebound discs 26 when the poles are closed.
Closing coil for applying electromagnetic force in the closing direction to the
Reference numeral 9 denotes a contact pressure spring for applying pressure when the contact 24 contacts, and reference numeral 30 denotes an opening holding spring for holding the contact 24 in an open state. In other words, the mechanical switch 2A is a mechanical switch having a pair of contacts that can be freely contacted and separated.

Next, the operation will be described with reference to FIG. FIG. 3 is for explaining the operation of the first embodiment, and shows a circuit as simplified as possible to which the switching device 8A of the first embodiment is applied. The configuration of the switching device 8A is also simplified. For example, an AC power supply 31 having a voltage of 3.8 kV, a switchgear 8A, a short-circuit impedance 32, and a load impedance 33 are connected in series. Assuming that the short-circuit impedance of this circuit is, for example, 0.3 ohm and the load impedance is, for example, 6.3 ohm, the short-circuit current is about 12.5 k
A, the load current will flow about 600A.

A description will be given of a case where the point A and point B in FIG. 3 are short-circuited and the switchgear 8A shifts from the open state to the closed state. First, the control unit 3A
When a closing signal is input to the thyristor 1A (see FIG. 1), an ignition signal is sent to the thyristor 1A via the control line 3b instantaneously.
In this case, the so-called closing time of the mechanical switch 2A is zero, and instantaneous closing becomes possible. Although in the case the resistor 10 is not current flows I ₁ of 12.5 kA, thyristor 1
From the resistor 10 to the A series is connected, the current is suppressed as low current I _3.

Assuming that the resistance value of the resistor 10 is 1 ohm, the flowing current is about 3 kA. In general, since the short-circuit impedance is an inductive load, the peak value of the current flowing when there is no resistor 10 may be about 30 kA, and the thyristor 1A needs to have a current withstand capability for this current. For example, by inserting the resistor 10 having a resistance of 1 ohm, it suffices to have a resistance to a current having a peak value of about 4.3 kA. The control unit 3A determines via the control line 3c that the circuit is in a short-circuit state from the current value detected by the current detector 11, and the thyristor 1
The ignition signal of A is stopped, and the fault current is cut off by the thyristor 1A. FIG. 4 schematically shows current waveforms flowing through the thyristor 1A and the mechanical switch 2A at this time. In the drawing, a broken line a indicates a fault current flowing without the resistor 10, and a solid line b indicates a fault current suppressed by the resistor 10. The thyristor current is cut off instantaneously,
No current flows because the mechanical switch 2A keeps the open state.

Next, consider the case where the circuit of FIG. 3 is not in a short-circuit state, but in a state where power can be supplied to the load impedance 33 (steady state). When the switchgear 8A is turned on from the open state to turn on the thyristor 1A in the steady state and enters the conductive state, a current of about 500 A flows through the circuit, and the load impedance 33 has a voltage of 3.3 kV, that is, a voltage of 86% of the power supply voltage. Is supplied. Current detector 11
When it is determined from the current detected by (FIG. 1) that the circuit is in a steady state, a closing command is sent from the control unit 3A (FIG. 1) to the mechanical switch 2A via the control line 3a, The type switch 2A is turned on. Impedance of the mechanical switch 2A Most sufficiently small current I ₂ when compared to the impedance of the thyristor 1A flows through the switch 2A,
As a result, the supply voltage to the load impedance 33 becomes 10
0%.

FIG. 5 shows the current waveform and the magnitude of the supply voltage of the load impedance 33 at this time. In the drawing, a solid line c represents a steady current suppressed by the resistor 10, and a solid line d represents a steady current. In the steady state, the power is supplied by the mechanical switch 2A. In this case, the firing signal to the thyristor 1A may be stopped. The current interruption is performed by the switch 2A, and the mechanical switch 2A requires, for example, an interruption capacity of 12.5 kA in the circuit of FIG. Resistor 1 inserted in series with thyristor 1A
The value of 0 is the voltage value to be supplied to the load during the time from when the thyristor 1A is turned on to when the mechanical switch 2A is turned on when the steady circuit is turned on, and the current that is suppressed by the resistance when the short circuit is turned on. It may be selected according to the value and the withstand current capacity of the thyristor 1A.

As described above, according to the first embodiment, the resistor is inserted in series with the thyristor, and the mechanical switch having the short-circuit current breaking capacity is connected in parallel with the series circuit of the thyristor and the resistor. Thereby, it is possible to reduce the withstand current capacity of the thyristor required when the short circuit is turned on.

Embodiment 2 FIG. 6 is a configuration diagram showing a second embodiment of the present invention. 6, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.
In the figure, 8B is a switchgear according to the present embodiment, 12B.
Is a reactor as a current limiting element. That is, in the present embodiment, the reactor 12 as a current limiting element is connected in series with the thyristor 1A. Other configurations are the same as those in FIG.

Next, the operation will be described. Thyristor 1
When A enters the fault circuit, the flowing fault current I ₃ is suppressed by the reactor 12. At this time, unlike the first embodiment, a direct current component is superimposed on the current. Therefore, the direct current component must be considered as the withstand current capability of the thyristor 1A. When the stationary circuit is turned on, when the load impedance 33 (FIG. 3) is a resistive load, the drop of the voltage supplied to the load impedance 33 can be made smaller than in the first embodiment. Other operations are the same as those in the first embodiment.

As described above, according to this embodiment, the reactor is inserted in series with the thyristor, and the mechanical switch having a short-circuit current interrupting capacity is connected in parallel with the series circuit of the thyristor and the reactor. It is possible to reduce the withstand current capacity of the thyristor required when the thyristor is turned on.

Embodiment 3 In the first and second embodiments, the current limiting elements are connected in series with the thyristors connected in parallel in opposite directions to each other, but those in which the current limiting elements are connected to the respective thyristors are connected in parallel. Well,
Similar effects can be obtained. In the first and second embodiments, the case where the current limiting element is a resistor, a reactor, or the like has been described. However, a nonlinear current limiting element having a non-linear resistance with respect to the current passing through current may be used. The same effect can be obtained. In the first and second embodiments, the circuit configuration of the single-phase portion has been described. However, the present invention may be applied to each of the three-phase circuits, and similar effects can be obtained.

[0029]

As described above, according to the first aspect of the present invention, a current limiting element for suppressing a fault current is connected in series with a semiconductor switch, and a series circuit of the semiconductor switch and the current limiting element is connected to the semiconductor switch. Because a mechanical switch with fault current interruption performance is connected in parallel, the current that flows when the fault circuit is turned on by a semiconductor switch is suppressed by a current-limiting element, and the current can be interrupted by a mechanical switch. Thus, there is an effect that the circuit has the function of instantaneously turning on the circuit, and the withstand current capacity required of the semiconductor switch can be reduced.

According to the second aspect of the present invention, in the first aspect of the present invention, an electromagnetic repulsion mechanism is used for the operation mechanism of the mechanical switch, so that the opening of the mechanical switch is caused by the electromagnetic repulsion. The time can be shortened, so that the same effects as those of the first aspect of the invention can be obtained. In addition, the switching can be performed instantaneously, and the closing and closing can be performed at a high speed. Further, since the configuration is such that a high-frequency current having a polarity opposite to the polarity when the commercial frequency current flowing through the contact portion is cut off can be superimposed, the same effect as the first aspect of the present invention can be obtained.

According to the third aspect of the invention, in the first aspect of the invention, since the current limiting element is constituted by the reactor, the input current by the semiconductor switch can be suppressed by the reactor. The same effects as those of the first aspect are obtained.

According to the fourth aspect of the present invention, in the first aspect of the present invention, since the current limiting element is constituted by a resistor, a current applied by the semiconductor switch can be suppressed by the resistor. There is an effect similar to that of the first aspect of the present invention.

According to the fifth aspect of the present invention, in the first aspect of the present invention, a non-linear current limiting element whose impedance changes with respect to a current value passing through the current limiting element is used. 2. The non-linear current-limiting element having a low impedance with respect to a load current level and a high impedance with respect to a large current such as a short-circuit current can be suppressed. The present invention has the same effect as the invention.

According to the sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, the semiconductor switch is constituted by a pair of thyristors antiparallel to each other. The same effects as those of the first aspect are obtained.

According to the seventh aspect of the present invention, in the first aspect of the present invention, the detecting means for detecting a current flowing when the semiconductor switch is turned on, and the detecting means A judgment unit for judging whether the value is a fault current or a steady current, wherein the turning on of the mechanical switch is controlled according to whether the current flowing when the semiconductor switch is turned on is the fault current or the steady current. In addition to the effects similar to those of the invention described above, there is an effect that the time required for shutting down when the fault circuit is turned on can be reduced, and the thermal withstand current required by the semiconductor switch and the current limiting element can be reduced.

According to an eighth aspect of the present invention, in the invention of the seventh aspect, there is provided means for detecting a current flowing when the semiconductor switch is turned on, and it is determined based on the value thereof that the fault circuit has been turned on. When the current is cut off by a semiconductor switch without turning on a mechanical switch,
In other words, when the semiconductor switch is turned on and the current suppressed by the current limiting element corresponds to the fault current, the current is instantaneously cut off by the semiconductor switch, so that the same effect as the first aspect of the present invention is obtained. At the same time, there is an effect that the time required for shutting down when the fault circuit is turned on can be reduced.

According to the ninth aspect of the present invention, in the invention of the seventh or eighth aspect, when it is determined that the semiconductor switch has turned on the steady state circuit based on the value of the current detection, the mechanical switch is used. When the semiconductor switch is turned on instantaneously, that is, when the current suppressed by the current limiting element does not correspond to the fault current when the semiconductor switch is turned on, control is performed so as to subsequently turn on the mechanical switchgear. Clauses 7 and 8
In addition to the effects similar to the above, there is an effect that the thermal current resistance required by the semiconductor switch and the current limiting element can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a structure of a mechanical switch used in the first embodiment shown in FIG.

FIG. 3 is a circuit diagram for explaining the operation of the switchgear shown in FIG.

FIG. 4 is a current waveform diagram for explaining the operation of the switchgear shown in FIG.

FIG. 5 is a current waveform diagram for explaining the operation of the switchgear shown in FIG.

FIG. 6 is a configuration diagram showing a second embodiment of the present invention.

FIG. 7 is a configuration diagram showing a conventional switching device.

[Explanation of symbols]

1A semiconductor switch, 2A mechanical switch, 3A
Control unit 8A, 8B switchgear, 10 resistor, 11 current detector, 12 reactor.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshinori Kimura 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Tomoe Takahashi 2-3-2 Marunouchi 3-chome, Chiyoda-ku, Tokyo Rishi Electric Co., Ltd.

Claims (9)

[Claims] 1. A semiconductor switch, a current limiting element connected in series to the semiconductor switch to suppress an accident current, and a detachable and freely connectable / disconnectable circuit connected in parallel to a circuit in which the semiconductor switch and the current limiting element are connected in series. A switchgear comprising: a mechanical switch having a pair of contacts, wherein the switch is turned on by the semiconductor switch, and the switch is turned off by the mechanical switch. 2. The mechanical switch according to claim 1, wherein a high-speed opening is possible by an electromagnetic repulsion mechanism.
Switchgear described in the item 3. The switchgear according to claim 1, wherein the current limiting element is a reactor. 4. The switchgear according to claim 1, wherein the current limiting element is a resistor. 5. The switching device according to claim 1, wherein the current limiting element is a nonlinear current limiting element having a resistance value that is non-linear with respect to a passing current value. 6. The switchgear according to claim 1, wherein said semiconductor switch comprises a pair of thyristors antiparallel to each other. 7. A detecting means for detecting a current flowing when the semiconductor switch is turned on, and a judging unit for judging whether the detected value is a fault current or a steady current, wherein the current flowing when the semiconductor switch is turned on is a fault. The switchgear according to any one of claims 1 to 6, wherein closing of the mechanical switch is controlled according to the current or the steady current. 8. When the current flowing when the semiconductor switch is turned on is an accident current, control is performed such that the semiconductor switch immediately cuts off the accident current without turning on the mechanical switch. The switchgear according to claim 7, wherein 9. The method according to claim 7, wherein when the current flowing when the semiconductor switch is turned on is a steady current, the mechanical switch is controlled to be turned on immediately. Switchgear.