WO2016199407A1

WO2016199407A1 - Direct-current interruption apparatus, direct-current interruption method

Info

Publication number: WO2016199407A1
Application number: PCT/JP2016/002759
Authority: WO
Inventors: 丹羽　芳充; 隆司大嶋; 正将安藤
Original assignee: 株式会社東芝
Priority date: 2015-06-09
Filing date: 2016-06-07
Publication date: 2016-12-15
Also published as: JP2017004726A

Abstract

According to the embodiments, a direct-current interruption apparatus has a switch, a semiconductor switch, a non-linear resistor, and a capacitor. The switch is a non-semiconductor device. The semiconductor switch is connected in parallel to the switch. The non-linear resistor is additionally connected in parallel to the switch and the semiconductor switch. The capacitor is additionally connected in parallel to the switch, the semiconductor switch, and the non-linear resistor.

Description

DC cutoff device, DC cutoff method

Embodiments of the present invention relate to a DC interrupting device and a DC interrupting method used for interrupting a DC current.

Generally, in order to send electric power, it is required that the system has a function of cutting off the transmission current in preparation for an accident or the like. For this purpose, a shut-off device is used. In particular, in direct current power transmission, there is no difficulty in the case of alternating current interruption because there is no current zero point in the transmitted direct current.

The current DC circuit breaker includes, for example, an energization path having a switch (switch) and a current interrupt path provided in parallel with the energization path and capable of gradually reducing the current. Normally, the switch on the current path is closed and a current is passed through the current path. In the event of an accident, the current interrupting path is temporarily turned on so that the current at the time of the accident can flow instead of the energizing path. On the other hand, by opening the switch and disabling the current in the energizing path, the current at the time of the accident is commutated to the current interrupting path side, and then the current in the current interrupting path is immediately limited to complete the breaking.

The current path of the DC interrupter is preferably as small as possible. This is because the electric resistance becomes a power loss during normal operation. Moreover, the faster the current switching from the current path to the current interrupt path of the DC interrupter, the better. This is because the current at the time of the accident increases as the delay increases, and the value of the current to be interrupted by the current interrupt path increases. When the current to be cut off increases, a large capacity current cut-off path is required, and the cut-off device increases in size.

The problem to be solved by the present invention is to provide a direct current interrupting device and a direct current interrupting method capable of suppressing a current-carrying loss at a normal time and avoiding an increase in size.

The DC circuit breaker of the embodiment has a switch, a semiconductor switch, a non-linear resistor, and a capacitor. The switch is a non-semiconductor device. The semiconductor switch is connected in parallel with the switch. The nonlinear resistor is further connected in parallel to the switch and the semiconductor switch. The capacitor is further connected in parallel to the switch, the semiconductor switch, and the nonlinear resistor.

Further, the DC cutoff method of the embodiment is a DC cutoff method using the above-described DC cutoff device, and is the following method. That is, (1) starting the electrode opening control of the switch, and (2) after starting the electrode opening control of the switch, the semiconductor switch in which the current flowing through the switch can be made to flow (3) After the confirmation is obtained, the semiconductor switch is turned off.

The lineblock diagram showing the direct-current circuit breaker of a 1st embodiment. The timing chart (total current) explaining the operation | movement of the DC circuit breaker shown in FIG. The timing chart (current of a semiconductor switch) explaining operation | movement of the direct-current circuit interrupter shown in FIG. 2 is a timing chart (capacitor + nonlinear resistor current) for explaining the operation of the DC interrupter shown in FIG. The timing chart explaining the operation | movement of the DC circuit breaker shown in FIG. 1 (applied voltage to a DC circuit breaker). The lineblock diagram showing the direct-current circuit breaker of a 2nd embodiment. 3 is a timing chart (total current) for explaining the operation of the DC interrupter shown in FIG. The timing chart (current of a semiconductor switch) explaining the operation | movement of the direct-current circuit breaker shown in FIG. 3 is a timing chart (capacitor + non-linear resistor current) for explaining the operation of the DC interrupter shown in FIG. FIG. 3 is a timing chart for explaining the operation of the DC breaker shown in FIG. 2 (applied voltage to the DC breaker). The lineblock diagram showing the direct-current circuit breaker of a 3rd embodiment. The lineblock diagram showing the DC circuit breaker of a 4th embodiment. The circuit diagram which shows the structural example of the commutation element 41 shown in FIG. 7 is a timing chart (total current) for explaining the operation of the DC interrupter shown in FIG. 7 is a timing chart (semiconductor switch current) for explaining the operation of the DC interrupter shown in FIG. 7 is a timing chart (capacitor + nonlinear resistor current) for explaining the operation of the DC interrupter shown in FIG. The timing chart explaining the operation | movement of the DC circuit breaker shown in FIG. 6 (applied voltage to a DC circuit breaker).

(First embodiment)
Based on the above, the DC interrupter of the embodiment will be described below with reference to the drawings. FIG. 1 shows the configuration of the DC interrupter of the first embodiment. As shown in FIG. 1, the DC circuit breaker includes a switch 11, a semiconductor switch 12, a nonlinear resistor 13, a capacitor 14, a switch 21, a current detection unit 22, a current detection unit 23, and a control unit 50.

The general operation of this device is as follows. In normal times, both the switches 11 and 21 are closed and left to right in the figure (or from right to left in the figure; hereinafter, for convenience of explanation, it is assumed that current is normally applied from the left to the right in the figure). Shed. When current interruption is required due to an accident or the like, the electrode opening control of the switches 11 and 21 is started by the control from the control unit 50, whereby the current that has been flowing through the switch 11 is controlled to a state in which current can flow. All commutation is performed on the semiconductor switch 12 side.

Then, immediately after the electrode opening control of the switches 11 and 21 is completed, the semiconductor switch 12 is turned off. This switching to OFF temporarily causes a current to flow through the capacitor 14 and the nonlinear resistor 13, but this current is limited by the nonlinearity of the nonlinear resistor 13 and the interruption is completed. Below, each component is demonstrated.

The switches 11 and 21 are non-semiconductor devices such as vacuum switches and gas switches, for example. Since it is a non-semiconductor device, power loss can be greatly reduced, unlike a configuration in which current is supplied to an on-state semiconductor device for energization during normal energization. The control of the electrode opening (and electrode closing) of the switches 11 and 21 is performed by the control unit 50 as described above. Although the switch 21 and the switch 11 are connected in series, when the pressure resistance of the switch 11 is sufficiently high, the switch 21 can be omitted.

The semiconductor switch 12 is controlled by the control unit 50 between an on state (a state in which current can flow) and an off state (a state in which current is interrupted). The semiconductor switch 12 is provided in parallel with the switch 11. As a specific example of the semiconductor switch 12, for example, two anti-parallel connection (parallel connection in which the forward directions are opposite to each other) of an IGBT (insulated gate bipolar transistor) and a diode are connected in series in the reverse direction. The unit element is configured, and a plurality of unit elements are connected in series so as to have two terminals as a whole. Other unit elements include an anti-parallel connection configuration of thyristors. The reason for connecting a large number in series is to ensure a withstand voltage in a DC cut-off state. In the drawing, a simplified display is used as a symbol.

The non-linear resistor 13 is connected in parallel with the series connection elements of the switches 11 and 21. The nonlinear resistor 13 functions at the final stage of the breaking operation of the DC breaker. Specifically, after the switches 11 and 21 become non-current and the semiconductor switch 12 becomes non-current, the current temporarily flows in a state where the charging voltage to the capacitor 14 reaches a predetermined level.

The capacitor 14 is further connected in parallel to a non-linear resistor 13 connected in parallel with the series connection elements of the switches 11 and 21. As a result, the charging current flows through the capacitor 14 immediately after the switches 11, 21 and the semiconductor switch 12 are switched to the current interruption. Therefore, since the voltage rise generated at both ends of the nonlinear resistor 13 is moderated and the peak is suppressed, the breakdown voltage characteristics of the switch 11 and the semiconductor switch 12 can be set loosely.

The current detection unit 22 detects the current flowing through the DC breaker and transmits it to the control unit 50. For this reason, the current detection unit 22 is provided in series outside the parallel connection of the switches 11 and 21, the nonlinear resistor 13 and the capacitor 14. As a specific example of current detection, for example, a resistor having a very small resistance value is inserted and the voltage across the resistor is detected.

The current detector 23 detects the current flowing through the semiconductor switch 12 and transmits it to the controller 50. For this reason, the current detection unit 23 is provided in series with the semiconductor switch 12. A specific example of this current detection is the same as that of the current detection unit 22 described above.

As described above, the control unit 50 controls the opening and closing of the switches 11 and 21 and the on / off control of the semiconductor switch 12. For these controls, the current detection results are obtained from the

current detection units

22 and 23, and information about the accident is obtained from an accident detection device (not shown). The occurrence of an accident may be determined by the control unit 50 by utilizing the current detection unit 22.

According to the first embodiment, when the electrode opening control of the switches 11 and 21 is started based on the accident information, for example, the current can flow due to the arc resistance between the electrodes. The current quickly commutates to the semiconductor switch 12 that is in the state. At this time, the current flowing through the semiconductor switch 12 is, for example, the current that should be cut off at the time of an accident. finish.

More specifically, after switching the semiconductor switch 12 to the OFF state, a current having the same value as the current flowing in the semiconductor switch 12 immediately before flows through the parallel element of the nonlinear resistor 13 and the capacitor 14. Since this current is initially a current for charging the capacitor 14, the voltage at both ends thereof is increased. When the voltage rise across the capacitor 14 reaches a predetermined value, a current starts to flow through the non-linear resistor 13 and the resistance value increases due to the non-linearity of the resistance. Therefore, the current decreases, and the increased resistance value substantially reduces the current to zero. Finally, the current interruption is completed.

The fact that the capacitor 14 is connected in parallel to the non-linear resistor 13 has an effect of gradually increasing the voltage generated at both ends of the non-linear resistor 13 instead of increasing rapidly. As a result, the maximum voltage to be applied to the switches 11 and 21 in the open state is suppressed, and the withstand voltage characteristics can be relaxed, so that the options of the switches 11 and 21 are expanded.

In this DC interrupter, the switches 11 and 21 are closed during normal energization, and current flows, and the on-state semiconductor device is not used for energization, so that power loss is greatly reduced. be able to. Further, when the semiconductor switch 12 is turned off, it can be said that the current flowing is still shortly after the current is quickly commutated, so that the allowable current increases as the semiconductor switch 12 (the semiconductor switch 12 increases in size). Can be avoided.

In the first embodiment, the switch 21 is provided in series with the switch 11. However, the switch 11 having a lower withstand voltage characteristic can be used. Since the switch 11 is connected to the semiconductor switch 12 in parallel and has a very small electrical conductivity even when the switch 11 is turned off, the voltage applied after the DC circuit breaker completes the DC circuit breakage is mostly. This is because the switch 21 side takes charge. For example, when the switch 21 is a high-breakdown-pressure gas switch and the switch 11 is a low-breakdown-pressure vacuum switch, this is a realistic configuration.

Next, with reference to FIG. 2, the time series operation of the DC interrupter shown in FIG. 1 will be further described. 2A to 2D are timing charts showing the operation of the DC interrupter shown in FIG.

FIG. 2A shows a time-series change in the total current (that is, the current detected by the current detection unit 22). The first stage in the figure (the stage before time A) is a state in which a normal current flows, and the breakdown is all the current flowing in the switches 21 and 11. As a matter of course, no current flows through the semiconductor switch 12 and the parallel connection of the nonlinear resistor 13 and the capacitor 14 before the time A (see FIGS. 2B and 2C).

When an accident occurs in the DC power transmission system at time A, the total current increases as shown in FIG. 2A. The fact that an accident has occurred is detected by an accident detection device (not shown) (time B), and the information is transmitted to the control unit 50. Receiving this, the control part 50 starts the electrode opening control of the switches 11 and 21 (time C). As a result, an arc resistance is generated in the switch 11 and a voltage is generated between both ends. Therefore, the current flowing in the switch 11 is commutated to the semiconductor switch 12 that is controlled so that the current can flow. When the electrode opening control of the switch 11 is continued and the distance between the electrodes spreads, the current does not flow to the switch 11 side, and the current flows only to the semiconductor switch 12 side (time D).

The state in which current does not flow through the switch 11 and current flows only through the semiconductor switch 12 is obtained by comparing the current detection result from the current detection unit 22 with the current detection result from the current detection unit 23 in the control unit 50. It can be understood that they are almost equal. That is, the control unit 50 can confirm that the current flowing through the switch 11 has been all commutated to the semiconductor switch 12 in a state where the current can flow through the current detection result. Note that the voltage applied to both ends of the switch 11 in a state where a current flows only in the semiconductor switch 12 is a voltage drop due to the on-resistance of the semiconductor switch 12, and is estimated to be several kV, for example.

After time D, the control unit 50 controls the semiconductor switch 12 to turn off the semiconductor switch 12 after the time when the electrode open state of the switches 11 and 21 is considered to be finally established (time E). . Thereby, as shown to FIG. 2C, an electric current flows into the nonlinear resistor 13 and the capacitor 14 temporarily.

In the first stage of flowing temporarily, a current having the same value as the current flowing in the semiconductor switch 12 immediately before that flows. This becomes a charging current for the capacitor 14, and as the capacitor 14 is charged and the voltage across the capacitor rises, a current flows through the nonlinear resistor 13 (time F). When a current flows through the non-linear resistor 13, the resistance value increases due to the non-linearity of the resistance, the current value is substantially zero due to the increased resistance value, and the current interruption is completed (time G). After time G, a DC voltage (for example, 300 kV) corresponding to the DC power transmission system is applied to the DC circuit breaker (see FIG. 2D).

As already described, since the capacitor 14 is charged by the capacitor 14 being connected in parallel to the nonlinear resistor 13, the voltage generated at both ends of the nonlinear resistor 13 is gradually increased and its peak is reduced. (See after time E in FIG. 2D). As a result, the maximum voltage to be applied to the switches 11 and 21 in the open state is suppressed, and the withstand voltage characteristics can be relaxed, so that the options of the switches 11 and 21 are expanded.

(Second Embodiment)
Next, FIG. 3 shows a DC circuit breaker according to the second embodiment. In FIG. 3, the same components as those already described are denoted by the same reference numerals, and the description thereof will be omitted unless there is a point to be added. In this 2nd Embodiment, there is no switch 21 which existed in the form shown in FIG. Regarding the influence caused by eliminating the switch 21, particularly the influence on the switch 11A, the description of the switch 11 in FIG. 1 can be referred to.

In the second embodiment, as a further difference from that shown in FIG. 1, a switch 31 is newly provided in series with the semiconductor switch 12. The switch 31 is a non-semiconductor device, and its electrode opening / closing control is performed by the control unit 50A. By providing the switch 31 as described above, an effect of further suppressing the current value when the semiconductor switch 12 is turned off can be obtained.

That is, if the electrode opening control is started slightly before the switch 31 is turned off, the current is reduced by the arc resistance, and the semiconductor switch 12 cuts off the reduced current. Therefore, an increase in allowable current for the semiconductor switch 12 can be avoided.

4A to 4D are timing charts showing the operation of the DC interrupter shown in FIG. As shown in FIG. 4, the electrode opening control of the switch 31 at the time E <b> 1 is started slightly before the time E that is the timing for turning off the semiconductor switch 12. Thereby, the arc resistance of the switch 31 is generated and the current of the semiconductor switch 12 is reduced. That is, an increase in allowable current for the semiconductor switch 12 can be avoided. Regarding the other points shown in FIG. 4, the description in FIG. 2 already described can be referred to.

(Third embodiment)
Next, FIG. 5 shows a DC interrupter according to a third embodiment. In FIG. 5, the same components as those already described are denoted by the same reference numerals, and the description thereof is omitted unless there is a point to be added. In the third embodiment, the switch 21 introduced in the form shown in FIG. 3 is also provided while the switch 21 existing in the form shown in FIG. 1 is provided. The advantages of providing the switch 21, particularly the advantages for the switch 11, have already been mentioned in the description with reference to FIG. 1. The advantages of the switch 31 have already been mentioned in the description with reference to FIG. The electrodes of the

switches

21 and 31 are controlled by the control unit 50B.

(Fourth embodiment)
Next, FIG. 6 shows a DC interrupter of a fourth embodiment. In FIG. 6, the same components as those already described are denoted by the same reference numerals, and the description thereof is omitted unless there is a point to be added. This fourth embodiment is based on the first embodiment shown in FIG. 1 as the configuration, and is a form in which a commutation element 41 is newly connected in parallel with the switch 11.

The commutation element 41 includes at least an element in which a functional element having a charge / discharge function and a semiconductor switch are connected in series. The commutation element 41 is controlled by the control unit 50C. The control unit 50C has on / off control of the semiconductor switch of the commutation element 41, and has a control function of charging the functional element of the commutation element 41 in advance and discharging at a predetermined timing.

FIG. 7 shows a configuration example of the commutation element 41. The commutation element 41 includes a capacitor 41a, a reactor 41b, and a semiconductor switch 41c connected in series. The capacitor 41a corresponds to the functional element having the charge / discharge function. In the state in which the semiconductor switch 41c is turned off under the control of the control unit 51C, the capacitor 41a is previously charged (that is, charged) between the two electrodes under the control of the control unit 51C. Is possible. Since the semiconductor switch 41c connected to one electrode of the capacitor 41a is in the OFF state, the charge accumulated in the capacitor 41a is hardly discharged in that state.

After that, when the semiconductor switch 41c is switched on by the control unit 50C at a predetermined timing, a discharge occurs when there is a current path that loops from one to the other between both electrodes of the capacitor 41a. The reactor 41b is inserted in order to keep the current flow at this time loose. The charging polarity of the capacitor 41a is positive on the right side and negative on the left side.

In this embodiment, switching to the ON state of the semiconductor switch 41c by the control unit 50C is performed simultaneously with the start of the electrode opening control of the switches 11 and 21. As a result, it is possible to reduce the current (arc current) flowing through the switch 11, and thereafter, the current is more quickly commutated to the semiconductor switch 12 which is in a state where current can be passed.
By reducing the arc current of the switch 11, the electrode damage of the switch 11 can be reduced and the life can be extended.

Further, with respect to the semiconductor switch 12, an effect of further suppressing the current value at the time of turning off can be obtained. That is, the commutation element 41 causes current commutation to the semiconductor switch 12 to occur more quickly, so that the current is cut off when the current is smaller. Therefore, an increase in allowable current for the semiconductor switch 12 can be avoided.

8A to 8D are timing charts showing the operation of the DC interrupter shown in FIG. As shown in FIG. 8, at time C, the electrode opening control of the switches 11 and 21 is started. At the same time, the commutation element 41 is activated, that is, the semiconductor switch 41c is turned on and the capacitor 41a is accumulated. Discharge the charge.

Then, the time D is advanced compared to the case shown in FIG. 2, and thus the time E is also advanced than the case shown in FIG. The time E is a timing at which the semiconductor switch 12 is turned off. Therefore, an increase in the allowable current can be further avoided as the semiconductor switch 12. Regarding the other points shown in FIG. 8, the description in FIG. 2 already described can be referred to.

As described above, according to the DC interrupter of each embodiment, the semiconductor switch is connected in parallel with the switch. With such a configuration, for example, when electrode opening control of the switch is started based on accident information, current is quickly commutated to the semiconductor switch that is turned on due to the arc resistance between the electrodes. At this time, the current flowing through the semiconductor switch is, for example, the current that should be cut off at the time of an accident.

Strictly speaking, after switching the semiconductor switch to the OFF state, a current having the same value as the current flowing in the semiconductor switch immediately before flows through the parallel element of the nonlinear resistor and the capacitor. The current initially becomes a charging current for the capacitor, and the voltage is increased by charging the capacitor. When the voltage increases, a current flows through the non-linear resistor, thereby increasing the resistance of the non-linear resistor and decreasing the current. Further, the current reaches zero and the current interruption is completed.

The fact that the capacitor is connected in parallel to the non-linear resistor has the effect of gradually increasing the voltage drop generated in the non-linear resistor instead of a sudden increase. As a result, the voltage to be applied to the open / closed switch is suppressed and the withstand voltage characteristic can be relaxed, thereby widening the choice of switch.

In this DC circuit breaker, of course, during normal energization, the switch is closed and current flows, and since the on-state semiconductor device is not used for energization, power loss can be greatly reduced. . Also, when the semiconductor switch is turned off, the current flowing through it is still small after being quickly commutated, so that an increase in allowable current can be avoided as a semiconductor switch.

Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 11, 11A ... Switch, 12 ... Semiconductor switch, 13 ... Nonlinear resistor, 14 ... Capacitor, 21 ... Switch, 22 ... Current detection part, 23 ... Current detection part, 31 ... Switch, 41 ... Commutation element, 41a ... capacitor, 41b ... reactor, 41c ... semiconductor switch, 50, 50A, 50B, 50C ... control unit.

Claims

A switch that is a non-semiconductor device;
A semiconductor switch connected in parallel with the switch;
A non-linear resistor further connected in parallel to the switch and the semiconductor switch;
A DC circuit breaker comprising: the switch; the semiconductor switch; and a capacitor connected in parallel to the nonlinear resistor.
A second switch connected in series with the parallel connection of the switch and the semiconductor switch, and having a higher withstand voltage than the switch;
2. The DC cutoff according to claim 1, wherein the nonlinear resistor and the capacitor are connected in parallel with respect to a parallel connection of the switch and the semiconductor switch and a series connection of the second switch, respectively. apparatus.
A second switch which is a non-semiconductor device connected in series with the semiconductor switch;
The DC breaker according to claim 1, wherein the switch is connected in parallel to a series connection of the semiconductor switch and the second switch.
The DC circuit breaker according to claim 1, further comprising an element connected in series with a second semiconductor switch and a second capacitor, further connected in parallel with the switch.
A switch that is a non-semiconductor device, a semiconductor switch connected in parallel to the switch, a non-linear resistor connected in parallel to the switch and the semiconductor switch, the switch, the semiconductor switch, and A DC cut-off method by a DC cut-off device comprising a capacitor further connected in parallel to the non-linear resistor,
Start electrode opening control of the switch,
After the start of the electrode opening control of the switch, confirm that all the current that was flowing through the switch has been commutated to the semiconductor switch that is allowed to flow current,
A DC cutoff method for switching the semiconductor switch to an off state after the confirmation is obtained.