JPH11283472A - Dc breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optimal open/close operation characteristic for the respective cutoff parts, and to optimally design the cutoff parts by respectively independently providing a first operation device for opening/closing the first cutoff part and a second operation device for opening/closing the second cutoff part. SOLUTION: An operation unit 3 of the first cutoff part 1 connected in parallel to a series circuit of a reactor 6 and a capacitor 5 and an operation unit 4 of the second cutoff part 2 connected in series to the first cutoff part 1 can be respectively independently operated. In this constitution, when grounding is caused since a DC power transmission system is hit by lighting, a self-exciting oscillating current is generated by an arc characteristic of the first cutoff part 1 to be superimposed on a direct current so as cut off an electric current by constituting an electric current zero point. Afterwards, a commutation circuit is separated from the system by cutting off the second cutoff part 2. At this time, since the operation units 3, 4 of the first cutoff part 1 and the second cutoff part 2 are independent, delay time of open/close operation between the cutoff parts of the second cutoff part 2 can be freely set to the first cutoff part 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-excited oscillation type DC circuit breaker used in a DC power transmission system.

[0002]

2. Description of the Related Art As an example of using a DC circuit breaker for protecting a neutral line of a DC power transmission system, there is a DC circuit breaker as shown in FIG. In the figure, an orthogonal transformer 8 and an orthogonal transformer 8 ′ are connected to a main line 9 of a DC transmission system via a neutral line 10. The other end of the orthogonal transformer 8 'is grounded, and the other end of the orthogonal transformer 8 is connected to a DC breaker.

A DC circuit breaker includes a commutation circuit in which a capacitor 5 and a reactor 6 are connected in series, and a arrester 7 and a first
The breaking units 1 are connected in parallel, and a second circuit
The cutoff units 2 are connected in series. 1st interruption part 1 and 2nd
The breaking unit 2 is opened and closed by the same operating device 40, but the second breaking unit 2 needs to be opened later than the first breaking unit 1 for the reason described later. Therefore, the first blocking unit 1
And the second interrupting unit 2 are mechanically connected to each other, so that the operation thereof is delayed.

Next, the operation of the DC breaker will be described. When a ground fault occurs due to a lightning strike or the like at the point P of the neutral wire 10, the first and second cutoff units 1 and 2 of the DC circuit breaker are provided.
And the DC circuit current is caused to flow to the ground to extinguish the arc at the ground fault point P. After that, only the first interrupting section 1 precedes by the opening command, so that an arc is generated at this contact, and a voltage is generated between the contacts. Then, the arc voltage increases with the opening of the contact while oscillating due to the instability of the arc. Since the arc generally has a negative voltage-current characteristic, the oscillating current flowing into the loop of the commutation circuit increases due to the voltage oscillation. When this amplitude exceeds the value of the DC current, the current I2 flowing through the first interrupting section 1 reaches the point of zero (T0), and the current I2 flowing through the first interrupting section 1 is cut off. Thereafter, the DC current I3 flows into the capacitor 5 through the second cut-off section 2, but the capacitor voltage Vc rises, so that the DC current I3 decreases to reach the zero (T01) point, and the current I1 flowing to the ground becomes Commuted to neutral.
FIG. 11 shows the current-voltage waveforms of each part during this time.

[0005] The lightning arrester 7 is provided with a capacitor 5 against an overvoltage generated during this series of operations and a voltage intruding from the outside.
And the reactor 6 is protected. In this state, the capacitor 5 is still charged and the voltage is applied to the lightning arrester 7, which is not preferable in terms of insulation.

In such a state, the charging current continues to flow, so that an induction failure is likely to occur. Therefore, after a certain period of time after the current interruption of the first interruption unit 1 is established, the second interruption unit 2 is opened to disconnect the commutation circuit. That is, it is a necessary condition that the second cut-off unit 2 is cut off after a certain time of the cut-off of the first cut-off unit 1.

[0007] Most of the neutral line faults are caused by lightning strikes, and the problem of multiple lightning strikes that occur continuously in a short time is particularly serious. In such a case, a method is adopted in which the fault current is removed by repeatedly turning on and off the DC breaker two to three times.

[0008]

In this system, the commutation circuit is cut off from the neutral line at an early time after the current cutoff of the first cutoff unit 1 by employing the second cutoff unit 2 having a current cutoff capability. I try to protect it. In addition, in order to rationalize the entire DC circuit breaker, it has been proposed that the first and second breaking units 1 and 2 be housed in the same container and opened and closed by a common operating device 40.

[0009] However, the two types of interrupting sections basically have contacts having different characteristics of current interrupting and circuit disconnection, and the required performance is greatly different. In particular, the first breaking part has the most important responsibility of generating a high arc voltage and breaking the DC main current. On the other hand, the second cut-off section only cuts off the charging current to the decaying capacitor,
No very high blocking performance is required. If they are housed in the same container, there is absolutely a lot of waste in space and a compact design is not achieved.

When the two shut-off sections are opened and closed by a common operating device, the different shut-off performances are obtained as described above. Is not a simple design. In addition, there is a problem that it is difficult to largely change the delay time because the adjustment of the delay time when the second cut-off unit performs the opening operation with a delay with respect to the first cut-off unit is mechanically determined.

The present invention (corresponding to claims 1 and 2) provides
The purpose of the present invention is to solve the above-mentioned problem. The purpose is to have an optimal opening / closing characteristic for each of the first and second shut-off sections, and to freely set the operation delay time of the second shut-off section. An object of the present invention is to provide a self-excited oscillation type DC circuit breaker that can be used.

[0012]

In order to achieve the above object, a first aspect of the present invention is to provide a commutation circuit in which a reactor and a capacitor are connected in series with a pair of mechanically detachable contacts. The first interrupting unit and the lightning arrester are connected in parallel, and the oscillating current generated in the reactor and the capacitor is superimposed on the DC current by the arc voltage characteristic of the first interrupting unit. In a DC circuit breaker that creates a current zero point and interrupts current,
A second interrupter having a pair of mechanically detachable contacts is electrically connected in series to the first interrupter, the commutation circuit, and the parallel circuit of the lightning arrester to open and close the first interrupter. A first operating device for operating and a second operating device for opening and closing the second blocking unit are provided independently of each other.

According to the first aspect, the first of the DC breakers is provided.
Since the actuators of the breaking part and the second breaking part are independent of each other, the degree of freedom of the time delay of the opening operation between the breaking parts can be increased, and the optimal opening / closing operation characteristics for the two breaking parts respectively. Is obtained, so that it is possible to design an optimal cutoff portion for both.

According to a second aspect of the present invention, in the DC circuit breaker according to the first aspect, a first operating device for opening and closing the first interrupting portion and a second operating device for opening and closing the second interrupting portion are provided. In the meantime, an interlock for locking the opening operation of the second blocking unit for a predetermined time after the completion of the opening operation of the first blocking unit is provided. According to this claim 2,
It is possible to accurately control the operation time of the first and second interruption units at the time of interruption, thereby improving the operation reliability.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a configuration diagram of a DC circuit breaker according to a first embodiment of the present invention (corresponding to claim 1). The configuration different from the conventional example of FIG.
First disconnection unit 1 connected in parallel to a series circuit of
And the operating device 4 of the second shut-off unit 2 connected in series to the first shut-off unit 1 are configured to be able to be operated independently of each other, and the other configurations are the same. , The same portions are denoted by the same reference numerals and the description thereof will not be repeated.

Next, the opening operation of this embodiment will be described with reference to FIGS.
Description will be made with reference to the time chart of FIG. When a lightning strike occurs at a DC transmission system, for example, point P in FIG. Then, the second interrupting section 2 is interrupted and the commutation circuit is separated from the system. At this time, since the operating device 3 and the operating device 4 of the first blocking unit 1 and the second blocking unit 2 are independent, the second blocking unit 2 is connected to the first blocking unit 1 as shown in FIG. Can be set freely.

Generally, the optimum delay time T differs depending on the frequency of lightning strikes and the characteristics of the DC transmission system, and it is a great advantage that the delay time T can be freely selected. Also,
Since the optimal opening / closing operation characteristics can be obtained for each of the two shut-off portions, an optimum shut-off portion design for both can be achieved. Also, as shown in FIG. 3, it is also possible to perform the opening / closing operation only on the first shutoff unit 1 a plurality of times, and to perform the shutoff operation after the completion of the last shutoff operation of the first shutoff unit 1. As described above, according to the present embodiment, since the operating devices of the first and second breaking units of the DC breaker are independent from each other, the degree of freedom of the time delay of the opening operation between the breaking units is increased. be able to. Since the optimal delay time varies depending on the frequency of lightning strikes and the characteristics of the DC transmission system, it is a great advantage that the delay time can be freely selected. Further, since the optimal opening / closing operation characteristics can be obtained for each of the two interrupting portions, it is possible to design an optimal interrupting portion for both. Therefore, it is possible to provide a DC circuit breaker that can be designed in a compact manner and leads to cost reduction.

FIG. 4 is a block diagram of a DC circuit breaker according to a second embodiment (corresponding to claim 2) of the present invention. The control circuit 12 is provided between the control unit 3 and the operation device 4 of the second shut-off unit 2 to control the operation time. Since other configurations are the same, the same portions are denoted by the same reference numerals, and redundant description will be omitted.

In the first embodiment, there is no restriction on the timing of the breaking operation. However, in the DC breaker of the present embodiment, two breaking operations are performed so that the first breaking unit 1 opens before the second breaking unit 2. Since the operation time is controlled by providing the control circuit 12 between the operation devices, the delay time during the shutoff operation can be always maintained. As described above, according to this embodiment, it is possible to accurately control the operation time of the first interruption unit and the second interruption unit at the time of interruption, and to improve the operation reliability.

FIG. 5 is a block diagram of a DC circuit breaker according to a third embodiment (corresponding to claim 2) of the present invention, and FIG. 6 is a specific control circuit diagram of FIG. This embodiment is different from the first embodiment in that a control circuit 12A is provided between the operating device 3A of the first interrupting unit 1 and the operating device 3B of the second interrupting unit 2 to control the operation time. That is the point. Since other configurations are the same, the same portions are denoted by the same reference numerals, and redundant description will be omitted.

5 and 6, in this embodiment, when a cutoff command is input and the open circuit coil 31 of the first cutoff unit 1 is excited, the open circuit operation starts. When the interruption is completed, the b-contact 31b of the auxiliary contact is closed. Then, the timer 33 incorporated therebelow is activated, and after a predetermined time, the a contact 33a of the timer 33 is closed. If the coil 32 for commanding the opening of the second interrupting section 2 is connected below the a contact 33a, the second interrupting section 2 can be opened after a predetermined delay time. If the open circuit command coil 32 of the second interrupting unit 2 and the b contact 31b of the first interrupting unit 1 are connected in series,
When the first blocking unit 1 is in the closed state, the second blocking unit 2
Is not accepted, it is possible to prevent malfunction when the timer fails.

According to the present embodiment, the hydraulic operating mechanism 3
It is possible to easily interlock between actuators of different types, such as the actuator of A and the actuator of the spring operating mechanism 3B, so that there is a wider range of choices for the operation method suitable for the shut-off section. It gets bigger and bigger. FIG. 6 shows only a part related to the present embodiment, and omits other controls and interlocks required as a circuit breaker.

As described above, according to this embodiment, the operating time of the first and second shut-off units can be accurately controlled regardless of the type of the operating device, so that the optimal operation for the shut-off unit can be controlled. It is possible to adopt a method, and it is possible to construct a reasonable DC circuit breaker that is more compact and leads to cost reduction.

FIG. 7 is a block diagram of a DC circuit breaker according to a fourth embodiment (corresponding to claim 2) of the present invention. A point that an interlocking valve (time control circuit) 13 using a hydraulic circuit is provided between the operation device of the device 3C and the operation device of the hydraulic operation device 3D of the second shutoff unit 2 to control the operation delay time. It is. Since other configurations are the same, the same portions are denoted by the same reference numerals, and redundant description will be omitted.

According to this embodiment, the first hydraulic operating mechanism 3C
When the pressure inside the cylinder changes due to the opening operation,
This is transmitted to the second hydraulic operating mechanism 3D via the interlocking valve 13, and the second hydraulic mechanism 3D also starts the opening operation. At this time, the delay time of the second shut-off unit 2 can be freely adjusted by adjusting the hydraulic pressure transmission speed of the interlocking valve 13. The hydraulic cylinder for a gas circuit breaker of the 1000 kV resistance cut-off type according to the present embodiment is disclosed in Japanese Patent Application No. 5-33223.
The configuration is the same as that of the hydraulic operating mechanism disclosed in Japanese Patent Application Laid-Open No. 6-64.

As described above, according to the present embodiment, the operation delay time control can be constituted only by the hydraulic circuit, so that it is possible to cope with the case where a specification for prohibiting the electric interlock is required. It is.

FIG. 8 is a control circuit diagram of an operating device relating to a DC breaker according to a fifth embodiment of the present invention (corresponding to claim 2).
The DC breaker to which this embodiment is applied has the same configuration as the DC breakers of the first to fourth embodiments, and a description thereof will be omitted. In addition, in the figure, only a portion related to the present embodiment is shown, and other controls and interlocks required as a circuit breaker are omitted.

For example, in the DC circuit breaker shown in FIG.
When the second blocking unit 2 is turned on while the blocking unit 1 is in the blocking state,
An inrush current may flow into the capacitor, which is not preferable. Also, an excessive electrical stress is applied to the lightning arrester 7.

In the present embodiment, as shown in the time chart of FIG. 9, if the first cut-off unit 1 is always turned on before the second cut-off unit 2, the reactor 6, the capacitor 5, and the lightning arrester 7 are short-circuited. Therefore, it is protected from the stress as described above.
Therefore, it is necessary to apply an interlock between the operating devices so that the first shut-off unit 1 precedes the second shut-off unit 2.

As shown in the control circuit diagram of the operating device in FIG.
In the present embodiment, when a closing command is input, first, the closing coil 34 of the first interrupting section 1 is excited, and when the first interrupting section 1 starts the closing operation and enters the closed state, the a contact 34a is closed.
At the same time, the timer 35 is turned on, and after a certain time, the a contact 35a of the timer is closed. If the closing coil 36 of the second interrupting section 2 is connected to a lower position of the a contact 35a, the second interrupting section 2 can be turned on with a predetermined time delay. Furthermore, if the a-contact 34a of the first interrupting unit 1 is connected in series to the closing coil 36 of the second interrupting unit 2, the second interrupting unit 2 cannot be turned on when the first interrupting unit 1 is in the open state. This prevents malfunctions at the time of failure.

As described above, in the present embodiment, at night, the first interrupting section is in the interrupted state and only the second interrupting section is not turned on, so that the inrush current can be prevented from flowing into the capacitor. In addition, an excessive electric stress is not applied to the lightning arrester. For this reason, the electrical specifications of the capacitor and the lightning arrester can be made rational and the life can be extended. This also leads to downsizing, streamlining, and cost reduction of the entire DC circuit breaker.

[0032]

As described above, the present invention (Claim 1)
According to (correspondence), since the operating devices of the first and second breaking units of the DC breaker are independent of each other, the degree of freedom of the time delay of the opening operation between the breaking units can be increased. In addition, since the two switching units can obtain the optimal opening / closing operation characteristics, it is possible to design an optimal switching unit, and to provide a DC breaker that is compact and can be reduced in cost.

Further, according to the present invention (corresponding to claim 2), the operation time of the first and second cut-off units at the time of cut-off can be accurately controlled, the reliability of operation is improved, and the ratio is improved. A simple DC circuit breaker can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a DC breaker according to a first embodiment of the present invention.

FIG. 2 is a time chart of an opening / closing operation of a first blocking unit and a second blocking unit in FIG. 1;

FIG. 3 is another time chart of the opening / closing operation of the first blocking unit and the second blocking unit in FIG. 1;

FIG. 4 is a configuration diagram of a DC breaker according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a DC circuit breaker according to a third embodiment of the present invention.

FIG. 6 is a control circuit diagram of FIG. 5;

FIG. 7 is a configuration diagram of a DC breaker according to a fourth embodiment of the present invention.

FIG. 8 is a control circuit diagram according to a fifth embodiment of the present invention.

FIG. 9 is a time chart at the time of the closing operation of FIG. 8;

FIG. 10 is a configuration diagram of a conventional DC circuit breaker.

FIG. 11 is a voltage / current waveform diagram generated at the time of a breaking operation of the DC breaker.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st interruption | blocking part, 2 ... 2nd interruption | blocking part, 3, 3A, 3B, 3
C, 3D, 4 ... Operator, 5 ... Capacitor, 6 ... Reactor, 7 ... Lightning arrester, 8 ', 8 ... Orthogonal transformer, 9 ... Main line, 1
0: neutral wire, 11: grounding part, 12, 12a: control circuit,
13 ... Hydraulic interlocking valve, 31 ... Open circuit coil of first shut-off part, 3
1b: b contact of the first breaking part, 32: open coil of the second breaking part, 33: timer, 33a: a contact of the timer 33, 34: closing coil of the first breaking part, 35: timer,
35a: a contact of the timer 35; 34a: a contact of the first cut-off section; 36: closing coil of the second cut-off section;
Actuator.

Claims (2)

[Claims] An arc of said first breaking part is connected in parallel to a commutation circuit in which a reactor and a capacitor are connected in series, and a first breaking part and a lightning arrester each having a pair of mechanically detachable contacts. Oscillating current generated in the reactor and capacitor by voltage characteristics is superimposed on DC current,
In a DC circuit breaker in which a current zero point is formed in a DC current flowing through the first cut-off unit to cut off a current, a mechanical connection and disconnection can be made to the parallel circuit of the first cut-off unit, the commutation circuit, and the lightning arrester. A first operating device for electrically opening and closing the first interrupting portion and a second operating device for opening and closing the second interrupting portion are electrically connected in series with a second interrupting portion having a pair of contacts. A DC circuit breaker, comprising: 2. The DC circuit breaker according to claim 1, wherein the first operating device for opening and closing the first interrupting portion and the second operating device for opening and closing the second interrupting portion are provided between the first operating device and the second operating device. A DC circuit breaker, comprising: an interlock for locking the opening operation of the second interruption unit for a predetermined time after the completion of the opening operation of the interruption unit.