JP2015079699A - Dc circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC circuit breaker capable of reducing internal resistance when supplying the power and capable of changing the flow direction of current at a short time at occurrence of accident.SOLUTION: The DC circuit breaker includes: a power supply main circuit breaker 1, 10; a shutoff device 11 connected in parallel; a non-linear resistance 4 connected in parallel; and a control unit 15 that controls the operation of each units. The power supply main circuit breaker 1, 10 is constituted of a power supply switch 1 and a power supply vacuum switch 10. The shutoff device 11 is constituted of a semiconductor breaker 3 and a commutation circuit 14 that injects the current inversely to the power supply main circuit breaker 1, 10. The power supply vacuum switch 10 is constituted of a vacuum switch 12 and a resistor 13.

Description

  Embodiments described herein relate generally to a DC circuit breaker that can improve energization characteristics.

  Conventionally, a high voltage DC circuit breaker using a semiconductor switch is known (for example, see Non-Patent Document 1).

  This type of DC circuit breaker is shown in FIG. In the DC circuit, an energizing switch 1 using a gas insulated switch and an energizing semiconductor switch 2 connected to a plurality of IGBTs are connected in series. In parallel with these, a semiconductor breaker 3 to which a plurality of IGBTs are connected and a non-linear resistor 4 for overvoltage protection are respectively connected.

  During normal operation, a direct current is applied by the energizing switch 1 and the energizing semiconductor switch 2. When an accident such as a short circuit occurs, the semiconductor circuit breaker 3 is energized, and the energization switch 1 and the energization semiconductor switch 2 are interrupted. When the energizing semiconductor switch 2 is cut off, current is commutated to the semiconductor breaker 3 in a few ms. When the commutation is completed, the semiconductor breaker 3 is cut off. The overvoltage generated by the breaking of the semiconductor circuit breaker 3 is attenuated by the non-linear resistor 4 to complete a series of breaking operations. For example, in the case of a 300 kV system, the overvoltage is about 500 kV.

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  The energizing semiconductor switch 2 had a large internal resistance and a large loss during energization. When a contact point that contacts and separates like the energizing switch 1 can be used, the contact resistance can be reduced, but it is difficult to operate in a short time of several ms. If the operation is not performed in a short time, the accident current increases and it becomes difficult to cut off. For this reason, the problem to be solved by the present invention is to provide a DC circuit breaker that can suppress internal resistance during energization and can be commutated in a short time.

  In order to solve the above-described problem, a DC circuit breaker according to an embodiment is connected in parallel to a main circuit switch for energization, a circuit breaker connected in parallel to the main circuit switch for energization, and the main circuit switch for energization. A non-linear resistor, a main circuit switch for energization, a control device for controlling the operation of the circuit breaker, the DC circuit breaker, the main circuit switch for energization, the circuit switch for energization, It is composed of an energizing vacuum switch connected in series to the energizing switch, and the circuit breaker is connected in series to the semiconductor circuit breaker and the semiconductor circuit breaker, and a reverse current is applied to the energizing main circuit switch. The energizing vacuum switch is constituted by a vacuum valve and a support resistor connected in parallel to the vacuum valve.

The circuit diagram which shows the structure of the direct-current circuit breaker which concerns on Example 1 of this invention. Sectional drawing which shows the structure of the vacuum switch for electricity supply which concerns on Example 1 of this invention. The figure explaining the voltage and electric current characteristic of the direct-current circuit breaker which concern on Example 1 of this invention. Sectional drawing which shows the structure of the vacuum switch for electricity supply which concerns on Example 2 of this invention. The circuit diagram which shows the structure of the conventional DC circuit breaker.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, a DC circuit breaker according to a first embodiment of the present invention will be described with reference to FIGS. 1 is a circuit diagram showing a configuration of a DC circuit breaker according to Embodiment 1 of the present invention, FIG. 2 is a cross-sectional view showing a configuration of a vacuum switch for energization according to Embodiment 1 of the present invention, and FIG. It is a figure explaining the voltage and electric current characteristic of the direct-current circuit breaker which concerns on Example 1 of invention. In addition, the same code | symbol was attached | subjected to the component similar to the past.

  As shown in FIG. 1, an energizing switch 1 using a gas-insulated switch and an energizing vacuum switch 10 using a vacuum valve are connected in series to the DC circuit. In parallel with these, a cutoff device 11 for assisting current cutoff and a non-linear resistor 4 for overvoltage protection are connected.

  The energizing vacuum switch 10 is connected in parallel with a vacuum switch 12 to a resistor 13 having a resistance higher than 1000 times the internal resistance of the breaking device 11. A semiconductor breaker 3 and a commutation circuit 14 connected to a plurality of IGBTs are connected in series to the breaker 11. Operations of main circuit devices such as the energizing switch 1, the energizing vacuum switch 10, the semiconductor circuit breaker 3, and the commutation circuit 14 are controlled by the control device 15, respectively. The main circuit device is stored in a gas insulating container filled with an insulating gas having a predetermined pressure.

  As shown in FIG. 2, the energizing vacuum switch 10 is provided with a vacuum valve 17 having a pair of contacts 16 that can be contacted and separated. A fixed side electrode 18 is provided on the fixed side of the vacuum valve 17, and a movable side electrode 19 is provided on the movable side. A movable shaft 21 penetrates through the movable electrode 19 via a contact 20 so as to be movable. The fixed electrode 18 and the movable electrode 19 are supported and fixed by a plurality of support resistors 22 made of high resistance such as carbon. The vacuum valve 17 corresponds to the vacuum switch 12, and the support resistor 22 corresponds to the resistor 13. Note that the support resistor 22 may be provided with an FRP plate to give mechanical strength.

  Next, the blocking operation will be described with reference to FIG.

  If an accident occurs at time t1 when the energizing switch 1 and the energizing vacuum switch 10 are closed, the accident current increases rapidly. The accident current reaches several to several tens of kA, and when it is detected by an accident detection device (not shown) (time t2), the control device 15 starts an interruption operation. First, the commutation circuit 14 is operated at time t3, and a reverse current is injected into the energizing switch 1 and the energizing vacuum switch 10. The capacitor of the commutation circuit 14 is charged in advance, and for example, a semiconductor switch that operates in a short time is used as the switch. By injecting the current, the currents of the energizing switch 1 and the energizing vacuum switch 10 are reversed from rising and rapidly attenuated. At the decaying time t4, the energizing switch 1 and the energizing vacuum switch 10 are simultaneously opened.

  At time t5, the current becomes almost zero, and the reverse current injection is completed. Then, a voltage generated by the internal resistance of the series body of the semiconductor breaker 3 and the commutation circuit 14 is applied to both ends of the energizing switch 1 and the energizing vacuum switch 10. The energizing switch 1 and the energizing vacuum switch 10 are configured to withstand this voltage. When the currents of the energizing switch 1 and the energizing vacuum switch 10 become substantially zero and commutation to the semiconductor circuit breaker 3 is completed, the semiconductor circuit breaker 3 is interrupted at time t6. Then, an overvoltage is generated at both ends of the energizing switch 1 and the energizing vacuum switch 10. The energizing switch 1 is configured to withstand overvoltage with gas insulation, and the energizing vacuum switch 10 suppresses overvoltage with the resistor 13 and does not cause dielectric breakdown between the contacts. The overvoltage is absorbed by the non-linear resistor 4 and completes the cutoff at time t7.

  Here, the energizing switch 1 and the energizing vacuum switch 10 are switches that energize the main circuit current, and these are collectively defined as the energizing main circuit switch.

  Thereby, since the energizing switch 1 and the energizing vacuum switch 10 use mechanical contacts, the contact resistance can be reduced, and loss during energization can be suppressed. Further, the commutation circuit 14 can energize a reverse current in a short time of several ms, and can improve the interruption characteristics. The current flowing through the energizing switch 1 and the energizing vacuum switch 10 at time t5 has been described as being substantially zero. However, as indicated by the alternate long and short dash line in FIG. 3, the current is almost zero by time t4. If the current width of the commutation circuit 14 is adjusted, the opening of the commutation circuit is facilitated, and the breaking characteristics can be further improved.

  According to the DC circuit breaker of the first embodiment, the main circuit current in the normal state is supplied by the main circuit switch for energization including the energization switch 1 and the energizing vacuum switch 10 connected in series, and in the event of an accident, the commutation circuit 14, the reverse current is injected and attenuated, and the energizing switch 1 and the energizing vacuum switch 10 are opened, so that the loss during energization can be suppressed, and in addition, a short time of several ms in the event of an accident. The reverse current can be injected over time, and the cutoff characteristics can be improved.

  In the first embodiment, the gas-insulating switch 1 is used as the energizing switch 1. However, a pair of contactable contacts such as an oil-insulated switch and an air-insulated switch having dielectric strength of the voltage class are provided. It is possible to use a switch that has a small contact resistance.

  Further, the support resistor 22 has been described with a plurality of rods. However, the structure can be simplified if a plurality of plates are provided above and below the vacuum valve 17 or the vacuum valve 17 is housed in a cylindrical shape. Can do.

  Next, a DC circuit breaker according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 4 is a cross-sectional view showing a configuration of a current-carrying vacuum switch according to Embodiment 2 of the present invention. The second embodiment differs from the first embodiment in that the vacuum valve is sealed at a low pressure. In FIG. 4, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 4, the support resistor 22 has a cylindrical shape, and both ends thereof are airtightly fixed to the fixed side electrode 18 and the movable side electrode 19. The movable side electrode 19 through which the movable shaft 21 penetrates is provided with a Y packing 23 so that it can move in an airtight manner. An insulating gas is sealed in the support resistor 22 at a gas pressure lower than that in the first embodiment. The outside is filled with an insulating gas at a predetermined pressure similar to that in the first embodiment.

  According to the DC circuit breaker of the second embodiment, in addition to the effects of the first embodiment, the pressure difference between the inside and outside of the vacuum valve 17 (inside the support resistor 22) can be reduced, and the reliability of the vacuum valve 17 Can be improved.

  According to the embodiment as described above, a commutation circuit is provided that energizes the main circuit current using a switch having a mechanical contact with a small contact resistance and injects a reverse current in the event of an accident. Loss during energization can be suppressed, and reverse current can be injected in a short time in the event of an accident.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example 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 scope 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 1 Switch for energization 2 Semiconductor switch for energization 3 Semiconductor circuit breaker 4 Nonlinear resistor 10 Vacuum switch for energization 11 Breaker 12 Vacuum switch 13 Resistor 14 Commutation circuit 15 Controller 17 Vacuum valve 22 Support resistor

Claims (5)

A main circuit switch for energization,
A breaker connected in parallel to the main circuit switch for energization;
A non-linear resistor connected in parallel to the energizing main circuit switch;
The main circuit switch for energization, a control device for controlling the operation of the shut-off device;
A DC circuit breaker comprising:
The main circuit switch for energization, a switch for energization,
It consists of a vacuum switch for energization connected in series with the switch for energization,
The circuit breaker, a semiconductor circuit breaker,
A series connection with the semiconductor circuit breaker and a commutation circuit for injecting a reverse current into the main circuit switch for energization,
The energizing vacuum switch, a vacuum valve,
A DC circuit breaker comprising a supporting resistor connected in parallel to the vacuum valve.   2. The DC circuit breaker according to claim 1, wherein the energizing switch is a switch having a pair of contacts that can be freely connected and separated.   The DC circuit breaker according to claim 1 or 2, wherein the supporting resistor is a plurality of resistors.   3. The DC circuit breaker according to claim 1, wherein the support resistor is cylindrical and the vacuum valve is housed. 4. The support resistor is cylindrical and the vacuum valve is housed,
The DC circuit breaker according to claim 1 or 2, wherein a gas pressure inside the support resistor is made lower than that outside.

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