JP3711334B2 - Switchgear - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a switchgear composed of a main circuit switch and a forced commutation circuit.
[0002]
[Prior art]
FIG. 11 is a block diagram showing the switchgear disclosed in the IEEJ Technical Committee Materials, SA-97-34, 1997 “Current Limiting Device Applying High-Speed Switch”.
In FIG. 11, 1 is a main circuit switch, 2 is an AC power supply, 4 is an inductance, 8 is a current sensor, 80 and 81 are capacitors and inductances constituting a forced commutation circuit, and 50, 52 and 53 are As shown in FIG. 12, the current flowing through the main circuit switch 1, the total current flowing through the main circuit switch 1 and the forced commutation circuit, and the high-frequency current flowing through the forced commutation circuit are shown.
[0003]
In the switchgear shown in FIG. 11, the main circuit switch 1 is a mechanical switch, and cannot be shut off unless it is at the current zero point. Therefore, by applying a high-frequency current 53 from the forced commutation circuit to the current flowing through the main circuit switch 1, a forced current zero point is created and the forced cutoff is performed.
[0004]
[Problems to be solved by the invention]
However, due to the shortage of the contact gap length necessary for shutting off the main circuit switch 1, there may be a case where the current cannot be interrupted at the first forced current zero point.
[0005]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems associated with the conventional example, and an object thereof is to obtain a switchgear having a forced commutation circuit capable of improving the reliability of current interruption.
[0006]
[Means for Solving the Problems]
The switchgear according to the present invention includes a bridge connection body including a plurality of units each including a main circuit switch, a switch and an element connected in reverse parallel to the switch, and a current flowing in a direction opposite to the switch, and a DC power source. Or a forced commutation circuit having a capacitor and connected in parallel to the main circuit switch; a detection means for detecting a state of a current flowing through the main circuit switch; and the forced commutation based on an output from the detection means. By controlling the switch of the current circuit, the current flowing through the main circuit switch is forcibly cut off at the current zero point by superimposing the output current supplied from the forced commutation circuit. And a control circuit that repeats forcibly creating a current zero point again by switching the switch of the current circuit.
[0007]
Further, the control circuit forcibly turns off the main circuit switch by setting a current flowing through the main circuit switch to a current zero point, and switches off the forced commutation circuit when the interruption fails. Returning the output current of the circuit to the DC power supply or the capacitor makes the current flowing through the main circuit switch to the current zero point again, and when the interruption fails, the forced commutation circuit is switched on again to force By increasing the output current of the commutation circuit, the current flowing through the main circuit switch is set to the current zero point again, and similarly, the current flowing through the main circuit switch is again forced to the current zero point by turning the switch on and off. It is characterized by repeating.
[0008]
In addition, the control circuit switches again from the forced commutation circuit to a circuit that circulates the output current flowing to the main circuit switch when the interruption at the current zero point forcing the current flowing to the main circuit switch fails. It is characterized by creating a current zero point.
[0009]
The detecting means is a sensor for measuring a current flowing through the main circuit switch.
[0010]
The allowable inter-electrode voltage of the switch in the forced commutation circuit is set to be higher than the voltage of the capacitor or the DC power source that rises due to regenerative energy absorption of the main circuit after the main circuit switch cuts off the current. Is.
[0011]
Further, instead of the forced commutation circuit having a bridge connection member, when the direct current flows in the main circuit switches, flow only reverse current switch and the person said switch and antiparallel connected the switch a unit consisting of elements, a DC power supply or a capacitor, is characterized in that the output current is replaced with other forced commutation circuit composed of a rectifying element for refluxing.
[0012]
Furthermore, a transformer is arranged between the main circuit switch and the forced commutation circuit.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
1 is a circuit diagram showing a switchgear with a forced commutation circuit that creates a forced current zero point according to Embodiment 1 of the present invention. As shown in FIG. 1, the switchgear with a forced commutation circuit includes a main circuit switch 1 and a forced commutation circuit 60 that is connected in parallel to the main circuit switch 1 and forcibly creates a current zero point. The forced commutation circuit 60 includes four sets of switches (S1, S2, S3, S4) 11, 21, 31, 41 and diodes (D1, D2, D3, D4) 12, 22, 32, 42 connected in reverse parallel. And a DC power supply 3.
[0014]
Here, the switches (S1, S2, S3, S4) 11, 21, 31, and 41 are self-extinguishing switches, for example, semiconductor switches such as IGBT and GTO, but thyristors that are not self-extinguishing switches. In the case of this switch, it is effective to add a forced commutation circuit. The diodes (D1, D2, D3, D4) 12, 22, 32, and 42 are so-called rectifier diodes, and are elements that allow only current in one direction to flow.
[0015]
The current flowing through the main circuit switch 1 is defined as a main circuit switch current 50, the output current from the forced commutation circuit 60 is defined as the output current 51 of the forced commutation circuit 60, and the current flowing through the main circuit is defined as the total current 52. A current sensor 8 and a control circuit 7 are provided as a detection and control system of the switching device with a commutation circuit. The current sensor 8 detects a main circuit switch current 50, and the control circuit 7 outputs the current sensor 8 to the output. Based on the switches (S1, S2, S3, S4) 11, 21, 31, 41 and the diode bridges (D1, D2, D3, D4) 12, 22, 32, 42 constituting the forced commutation circuit 60 . The current sensor 8 may detect the state of the current flowing through the main circuit switch 1 based on a voltage measured instead of the sensor that measures the voltage across the main circuit switch 1. In FIG. 1, 4 indicates the inductance of the main circuit, and 5 indicates the inductance of the forced commutation circuit 60.
[0016]
Further, as the forced commutation circuit 60, as shown in FIG. 2, the DC power supply 3 in FIG. The capacitor 301 is useful for rapid charging / discharging and frequent use, but may be a power storage device such as a large-capacity battery for specifications other than rapid charge / discharge and frequent use.
[0017]
Next, the interruption | blocking operation | movement of the switchgear with a forced commutation circuit is demonstrated. In the event of an emergency such as a ground fault on the main circuit, a short circuit between other phases, or when the current flowing through the main circuit increases or when the voltage drops, or when the main circuit current is interrupted arbitrarily, the main circuit switch 1 is In response to the opening command from the control circuit 7, the contact is opened.
[0018]
FIG. 3 shows waveforms of the main circuit switch current 50, the output current 51 of the forced commutation circuit and the total current 52, and the moving distance 550 of the movable contact in the main circuit switch 1 as the current flowing through each part. In FIG. 3, 551 is a moving distance range with a blocking probability of 90%, 552 is a moving distance range with a blocking probability of 95%, and 553 is a moving distance range with a blocking probability of 100%.
[0019]
When the main circuit switch current 50 first reaches the current zero point after the output current 51 of the forced commutation circuit 60 is superimposed, the moving distance range 551 of the movable contact of the main circuit switch current 50 is a moving distance sufficient for current interruption. Because it has not reached, there is a possibility of failure to shut off. Therefore, when the interruption fails, the generation of the current zero point of the main circuit switch current 50 is repeated until the main circuit switch 1 cuts off the main circuit switch current 50. Therefore, the control circuit 7 controls the output current 51 of the forced commutation circuit 60 to repeat the increase and decrease shown in FIG. 3 based on the detection of the current 50 of the forced commutation circuit by the current sensor 8.
[0020]
FIG. 4 shows the waveforms of main circuit switch current 50, forced commutation circuit output current 51 and total current 52, the waveform of capacitor voltage 53 of capacitor 301 in FIG. 2, and the switch (S1). Eleven interelectrode voltage waveforms are shown. In FIG. 4, 54 is the initial charge voltage of the capacitor voltage 53, 55 is the voltage of the capacitor after being shut off, 56 is the amount of change in voltage after absorbing regenerative energy after being shut off. After the main circuit switch current 50 is cut off by the main circuit switch 1, the capacitor 301 absorbs the regenerative energy of the main circuit and obtains a voltage Vcf55 of the cut-off capacitor.
[0021]
Next, control for repeatedly increasing and decreasing the output current 51 of the forced commutation circuit 60 will be described with reference to FIG. FIG. 5 shows the output current 51 of the forced commutation circuit 60, the output voltage 57 of the forced commutation circuit 60, and the switch state in a system using feedback of current to the DC power supply 3 or the capacitor 301. For example, when the main circuit switch current 50 is the current in the direction of the arrow in FIG. 1, the control circuit 7 detects the current direction from the current sensor 8 and enters the switch (S1) 11 and switch (S4) 41 to issue a command. Thus, the switch (S1) 11 and the switch (S4) 41 are turned on, and the output current 51 of the forced commutation circuit 60 flows to the main circuit switch 1.
[0022]
When the main circuit switch 1 fails to shut off, the control circuit 7 detects from the current sensor 8 that the main circuit switch 1 fails to shut down and a current is flowing, and immediately detects the switch (S1) 11 and the switch (S4). ) Issue a cut command to 41. When the switch (S1) 11 and the switch (S4) 41 cut off the current, the output current 51 of the forced commutation circuit 60 is fed back to the DC power supply 3 or the capacitor 301 through the diodes (D2) 22 and (D3) 32. It flows while decreasing.
[0023]
When the main circuit switch current 50 becomes the current zero point again and the main circuit switch 1 cannot be cut off at this time, the control circuit 7 fails to cut off the main circuit switch 1 from the current sensor 8 and the current flows. When this is detected, the switch (S1) 11 and the switch (S4) 41 are entered to issue a command. By supplying the forced commutation circuit output current 51, the forced commutation circuit output current 51 increases, and the main circuit switch current 50 reaches the third current zero point.
[0024]
The forced commutation circuit output current 51 is repeatedly increased and decreased by repeating the above steps and repeating the switch (S1) 11 and the switch (S4) 41 until the main circuit switch 1 cuts off the main circuit switch current 50. I can do it. When the main circuit switch current 50 is opposite to the direction of the arrow in FIG. 1, the forced commutation circuit output current 51 is such that the main circuit switch current 50 repeats zero when the switch (S2) 21 and the switch (S4) 31 are turned on and off. It flows in the direction opposite to the direction in 1 and repeats increasing and decreasing.
[0025]
FIG. 6 shows the output current 51 of the forced commutation circuit, the output voltage 57 of the forced commutation circuit 60, and the switch state in a system using current recirculation. Similar to the method of FIG. 5, when the main circuit switch current 50 is the current in the direction of the arrow in FIG. 1, the control circuit 7 detects the current direction from the current sensor 8, and switches (S1) 11 and (S4) 41, the command is issued, the switch (S1) 11 and the switch (S4) 41 are turned on, and the output current 51 of the forced commutation circuit flows to the main circuit switch 1.
[0026]
When the main circuit switch 1 fails to shut down, the control circuit 7 detects from the current sensor 8 that the main circuit switch 1 fails to shut down and the current is flowing, and immediately switches to the switch (S4) 41, (S3) Enter 31 and issue a command. When the switch (S4) 11 cuts off the current and the switch (S3) 31 is turned on, the forced commutation circuit output current 51 decreases while circulating.
[0027]
If the main circuit switch current 50 becomes the current zero point again and the main circuit switch 1 cannot be cut off at this time, the control circuit 7 has failed to cut off the main circuit switch 1 from the current sensor 8 and the current is flowing. Is detected, enters the switch (S4) 41 and issues a command to the switch (S3) 31. By supplying the forced commutation circuit output current 51, the forced commutation circuit output current 51 increases, and the main circuit switch current 50 reaches the third current zero point.
[0028]
By repeating this, the switch (S1) 11, the switch (S4) 41, and the switch (S3) 31 are repeatedly turned on and off until the main circuit switch 1 cuts off the main circuit switch current 50. The output current 51 can be repeatedly increased and decreased. Further, when the forced commutation circuit output current 51 is circulated, even if the switch (S4) 41 and the switch (S2) 21 are turned on and the switch (S1) 11 and the switch (S3) 31 are turned off, the forced commutation circuit is similarly provided. The output current 51 can be repeatedly increased and decreased.
[0029]
When the main circuit switch current 50 is opposite to the arrow direction in FIG. 1, the switch (S2) 21, the switch (S3) 31, the switch (S1) 11 is turned on or off, or the switch (S2) 21, the switch (S3) 31, In the switch (S4) 41, the forced commutation circuit output current 51 flows in a direction opposite to the direction shown in FIG. 1 so that the main circuit switch current 50 repeats the zero point, and similarly increases and decreases repeatedly.
[0030]
Next, the breakdown voltage specifications of the switches (S1, S2, S3, S4) 11, 21, 31, 41 will be described. FIG. 7 shows waveforms of main circuit switch current 50, forced commutation circuit output current 51, total current 52, capacitor voltage 53 of capacitor 301 in FIG. The waveform of the inter-electrode voltage and the states of the switches (S1, S2, S3, S4) 11, 21, 31, 41 are shown.
[0031]
After the main circuit switch 1 cuts off the main circuit switch current 50, the regenerative energy of the main circuit flows into the capacitor 301, and the capacitor voltage 55 after the cut-off becomes Vcf. At this time, for example, the voltage between the electrodes of the switch (S1) 11 is Vcf. Therefore, it is necessary to take a measure such as selecting a switch with a withstand voltage between the poles of the switch (S1) 11 larger than Vcf, reducing the inductance of the main circuit, or setting the specification of the main circuit switch current 50 smaller. .
[0032]
Next, the configuration of the main circuit switch 1 will be described with reference to FIG. In FIG. 8, 90 is a vacuum valve, 91 is a fixed contact, 92 is a movable contact, 93 is an opening coil, 94 is a closing coil, 95 is a repulsion plate, 96 is a contact pressure generating / opening holding mechanism, 97. Is an upper terminal, and 98 is a lower terminal. An electromagnetic repulsion mechanism for opening and closing the opening coil is composed of an opening coil 93, a closing coil 94, and a low electric resistance material repulsion plate 95. Although not shown, a pulse is applied from the power source of the charging capacitor. Opening and closing is driven by discharging current to these coils. The opening coil 93, the closing coil 94, and the repulsion plate 95 face each other.
[0033]
Next, the opening operation will be described. In FIG. 8, the contact pressure generating / opening holding mechanism 96 generates a load in the closing direction upward on the paper surface so that the movable contact 92 and the fixed contact 91 are not separated even by the electromagnetic repulsive force due to the maximum allowable energization current of the vacuum valve 90. The movable contact 92 is pressed against the fixed contact 91. When a pulse current is discharged to the opening coil 93, a magnetic field is generated, and an induced current flows through the repulsion plate 95 due to the interaction. The repulsion plate 95 is electromagnetically repelled in the opening direction downward with respect to the opening coil 93. Receive power.
[0034]
When the electromagnetic repulsive force exceeds the load in the closing direction upward in the drawing by the contact pressure generation / opening holding mechanism 96, the movable electrode 5 connected to the repulsion plate 95 operates and accelerates downward. The contact pressure generation / opening holding mechanism 96 holds the opening when the opening distance is exceeded. In a normal vacuum switch, the time from the opening command until the contact is released is 20 to 30 ms, but in a switch using this electromagnetic repulsion opening mechanism, the time is within 3 ms. Because the main circuit switch 1 opens before the main circuit switch current 50 increases in the event of a short circuit in the main circuit, forced commutation can be performed quickly, so there is no need to increase the forced commutation circuit output current. The capacity of the circuit can be reduced.
[0035]
Embodiment 2. FIG.
FIG. 9 is a block diagram showing a switchgear according to Embodiment 2 of the present invention, and shows an embodiment of forced commutation interruption when the main circuit current switch current 50 is a direct current. In FIG. 9, the forced commutation circuit 60 includes a DC power supply 3, a switch (S1) 11, a diode 12, a diode 43, and an output inductance 5 of the forced commutation circuit. Similarly to the first embodiment, the DC power supply 3 may be replaced with the capacitor 301 and charged by the main circuit.
[0036]
Next, the breaking operation of the switchgear with a forced commutation circuit according to the second embodiment will be described. As with the first embodiment, the main circuit switch 1 receives a contact opening command from the control circuit 7 and performs contact opening. As in FIG. 3 of the first embodiment, when the moving distance 550 of the movable contact in the main circuit switch 1 first becomes the current zero point after the output current 51 of the forced commutation circuit is superimposed, the main circuit switch current 50 Since the moving distance range 551 of the movable contact does not reach the moving distance sufficient for current interruption, there is a possibility of failure of interruption.
[0037]
Therefore, when the interruption fails, the generation of the current zero point of the main circuit switch current 50 is repeated until the main circuit switch 1 cuts off the main circuit switch current 50. For this reason, the output current 51 of the forced commutation circuit is controlled so as to repeatedly increase and decrease by using current circulation as in FIG. When the main circuit current switch current 50 is a direct current, the forced commutation circuit can sufficiently function even if it is configured with fewer switches and diodes than the first embodiment.
[0038]
Embodiment 3 FIG.
FIG. 10 is a block diagram showing a switchgear according to Embodiment 3 of the present invention. The forced commutation circuit current output from the forced commutation circuit 60 is smaller than the main circuit current switch current 50, and the transformer conversion is performed. An embodiment in which the forced commutation circuit current 51 is increased will be described. In FIG. 10, reference numeral 70 denotes a transformer, and the forced commutation circuit 60 has the same configuration as that of the first or second embodiment, and n is a winding ratio smaller than 1. In the switch and the diode configured by the forced commutation circuit 60, the current that can be passed is limited, and the forced commutation circuit current is larger than the main circuit current switch current 50.
[0039]
【The invention's effect】
As described above, according to the present invention, the opening of the movable contact of the main circuit switch can be more reliably interrupted by controlling the switching of the switch of the forced commutation circuit and repeatedly creating the current zero point again. The reliability of current interruption can be improved by moving the distance.
[0040]
In addition, when the switch in the forced commutation circuit cuts off the output current of the forced commutation circuit, the output current of the forced commutation circuit is fed back to the DC power supply or capacitor, so that the current flowing through the main circuit switch is quickly returned to the current zero point. As a result, the reliability of current interruption can be improved by moving the movable contact of the main circuit switch to the opening distance that more reliably cuts off.
[0041]
In addition, when the switch in the forced commutation circuit turns on and off the output current of the forced commutation circuit, the output current circulates, so that the current flowing through the main circuit switch is quickly re-established so that the main circuit switch is movable. The reliability of current interruption can be improved by moving the contact distance to an opening distance that more reliably interrupts the contact.
[0042]
If the main circuit switch cannot be shut off at the forced zero point, the control circuit detects the current with a sensor that measures the current of the main circuit switch, and controls the forced commutation circuit, thereby reducing the output current of the forced commutation circuit. The current flowing through the main circuit switch can be quickly re-established again, so that the movable contact of the main circuit switch can be moved to the opening distance that more reliably cuts off, and the reliability of current interruption is improved. Can be improved.
[0043]
In addition, by setting the allowable inter-electrode voltage of the switch in the forced commutation circuit higher than the voltage of the capacitor or the DC power source that has increased in voltage due to the absorption of main circuit regenerative energy, it is possible to prevent overvoltage damage of the switch in the forced commutation circuit. it can.
[0044]
In addition, when a direct current flows through the main circuit switch, the configuration of the forced commutation circuit can be achieved with a small number of components. By switching the output current of the forced commutation circuit with the switch in the forced commutation circuit, the output current is By recirculating the current flowing through the main circuit switch, the current zero point is quickly created again, so that the movable contact of the main circuit switch is moved to the opening distance that more reliably cuts off, improving the reliability of the current cut-off. be able to.
[0045]
Furthermore, when the current from the forced commutation circuit is smaller than the current flowing through the main circuit current switch, a transformer is placed between the main circuit switch and the forced commutation circuit, so that Is larger than the current flowing through the main circuit current switch.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a switchgear with a forced commutation circuit that creates a forced current zero point according to Embodiment 1 of the present invention;
2 is a circuit diagram showing a switchgear in which the DC power supply 3 shown in FIG.
3 is an explanatory diagram showing waveforms of a main circuit switch current 50, a forced commutation circuit output current 51 and a total current 52 in FIGS. 1 and 2 and a moving distance 550 of a movable contact in the main circuit switch 1. FIG.
4 is a diagram illustrating waveforms of the main circuit switch current 50, the output current 51 and the total current 52 of the forced commutation circuit, the waveform of the capacitor voltage 53 of the capacitor 301, and the waveform of the interelectrode voltage of the switch 11 in FIG. FIG.
FIG. 5 is an explanatory diagram showing an output current 51 of the forced commutation circuit 60, an output voltage 57 of the forced commutation circuit 60, and a switch state in a method using feedback of current to the DC power supply 3 or the capacitor 301; .
FIG. 6 is an explanatory diagram showing an output current 51 of a forced commutation circuit, an output voltage 57 of a forced commutation circuit 60, and a switch state in a system using current recirculation.
7 is a waveform of the main circuit switch current 50, the output current 51 of the forced commutation circuit, and the total current 52; the waveform of the capacitor voltage 53 of the capacitor 301 in FIG. 2; the waveform of the interelectrode voltage of the switch 11; , 21, 31, 41 are explanatory diagrams showing states.
8 is a configuration diagram of a main circuit switch 1. FIG.
FIG. 9 is a block diagram showing a switchgear according to Embodiment 2 of the present invention.
FIG. 10 is a configuration diagram showing a switchgear according to Embodiment 3 of the present invention.
FIG. 11 is a block diagram showing a switchgear disclosed in IEICE Technical Committee Materials, SA-97-34, 1997 “Current Limiting Device Applying High Speed Switch”.
12 is an explanatory diagram showing a current flowing through the main circuit switch 1 of FIG. 11, a total current flowing through the main circuit switch 1 and the forced commutation circuit, and a high-frequency current flowing through the forced commutation circuit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Main circuit switch, 3 DC power supply of forced commutation circuit, 4 Main circuit inductance, 5 Forced commutation circuit output inductance, 7 Control circuit, 8 Current sensor 11, 21, 31, 41 Switch, 12, 22, 32, 42 diode, 43 diode, 60 forced commutation circuit, 301 capacitor.

Claims (7)

A main circuit switch;
A bridge connection body having a plurality of units in combination of a switch and an element connected in reverse parallel with the switch and a device that allows only a current to flow in the opposite direction to the switch, and a DC power supply or a capacitor, and in parallel with the main circuit switch A connected forced commutation circuit;
Detecting means for detecting a state of a current flowing through the main circuit switch;
By controlling the switch of the forced commutation circuit based on the output from the detection means, the current flowing through the main circuit switch is forcibly set to the current zero point by superimposing the output current supplied from the forced commutation circuit. And a control circuit that repeats forcibly creating a current zero point again by switching the switch of the forced commutation circuit. The switchgear according to claim 1,
The control circuit forcibly sets the current flowing through the main circuit switch to a current zero point and shuts off the main circuit switch. When the shut-off fails, the control circuit switches off the forced commutation circuit. The output current is fed back to the DC power supply or the capacitor, so that the current flowing through the main circuit switch is set to the current zero point again. In addition, when the shutoff fails, the forced commutation circuit is switched on again to force the commutation. The circuit output current is increased, the current flowing through the main circuit switch is set to the current zero point again, and the current flowing through the main circuit switch is again forced to the current zero point by turning the switch on and off in the same manner. An opening / closing device characterized by that. The switchgear according to claim 1,
The control circuit switches the current zero point again by switching from the forced commutation circuit to the circuit that circulates the output current flowing to the main circuit switch when the interruption fails at the current zero point forcing the current flowing through the main circuit switch. Opening and closing device characterized by making. The switchgear according to any one of claims 1 to 3,
The switchgear characterized in that the detection means is a sensor for measuring a current flowing through the main circuit switch. The switchgear according to any one of claims 1 to 4,
A switching device characterized in that the allowable inter-electrode voltage of the switch in the forced commutation circuit is set higher than the voltage of the capacitor or the DC power source that rises due to regenerative energy absorption of the main circuit after the main circuit switch cuts off the current. . The switchgear according to any one of claims 1 to 5,
Instead of the forced commutation circuit having a bridge connection member, when the direct current flows in the main circuit switches, the switches and the equivalent the switch opposite parallel connected the switching from element to flow only reverse current A switchgear characterized by being replaced by another forced commutation circuit comprising a unit , a DC power source or a capacitor, and a rectifier for circulating output current. The switchgear according to any one of claims 1 to 5,
A switchgear characterized by disposing a transformer between the main circuit switch and the forced commutation circuit.

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