JP2993768B2 - Distribution line protection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection device for a distribution line for extinguishing an arc discharge generated in a system to protect a line.

[0002]

2. Description of the Related Art As shown in FIG. 1, a substation H supplies power to a three-phase distribution line 2 on which a circuit breaker 1 is installed.
On the secondary side of the circuit breaker 1, a detection unit such as a current transformer 3 or a grounding transformer 4 is provided, and the circuit breaker 1 is controlled by a protection relay 5 that detects a line fault by a detection signal.
The distribution line 2 is a normally closed line switch SW1-SW.
N, and the front of the track is configured to be connectable to a nearby distribution line (not shown).

However, when a short circuit accident occurs in the conventional distribution line 2 as described above, the circuit breaker 1
It takes about 12 cycles at commercial frequency (approximately 0.2 seconds for a 60Hz system) before the circuit is released. For this reason, if an arc current is generated in the line due to an accident due to a lightning surge or the like, the line equipment may be considerably damaged before the circuit breaker 1 is opened.

[0004]

SUMMARY OF THE INVENTION The present invention extinguishes an arc discharge generated in a distribution line to reduce damage to the line, suppresses the opening of a circuit breaker, reduces the number of power failures, and protects the circuit. An object of the present invention is to provide a protection device for a distribution line which is easily separated from a line by a switch to facilitate maintenance.

[0005]

In order to achieve the above object, the present invention provides first current detecting means in a distribution line,
A normally closed protection switch and an off-state thyristor switch are sequentially provided on the branch line of the distribution line to short-circuit the ends of the thyristor switch, and a second current detection is provided between the protection switch and the thyristor switch. Means for controlling the thyristor switch by judging that the signal level from the first current detecting means has exceeded a set value, and opening the protective switch by a signal from the second current detecting means. The measures of claim 1 are taken. Further, the protection switch is configured to detect the short-circuit current flowing for a set time or more, and to open the circuit breaker at the substation by detecting that the system has no voltage.

[0006]

When the first current detecting means detects an overcurrent in the distribution line, the thyristor switch in the off state is activated at the branch point of the line to short-circuit the distribution line, thereby reducing the overcurrent flowing in the line. . When a leakage current is generated in the thyristor-type switch in the OFF state, the second current detection means detects the leakage current, and the protection switch is opened by the signal to disconnect the electric circuit between the thyristor switch and the distribution line. Further, when the thyristor switch is in the ON state after the set time by the means of claim 2, the protection switch is opened by detecting the no-voltage of the system due to the opening of the circuit breaker. It is possible to prevent the propagation of a failure.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. As shown in FIG. 1, a first current detecting means 6 is provided for each phase of the distribution line 2, and its signal line 6a is connected to a determination circuit 8 provided in a thyristor device 7. As the first current detecting means 6, a current transformer, an optical sensor for detecting a magnetic field, or the like is used. When an optical sensor is used, an optical fiber cable is used as the signal line 6a, and a light emitting diode (LED) or a photodiode (PD) is used.
Means for mutual conversion between electric / optical signals such as described above are provided in the determination circuit 8.

The judgment circuit 8 is connected via a thyristor control circuit 9 to a thyristor-type switch 10 in an off-state, which is installed with a terminal short-circuited to a branch line 11 from the distribution line 2. The judging circuit 8 receives the signal from the current detecting means 6, judges the magnitude of the overcurrent in the distribution line 2 based on the intensity level, and when the signal exceeds the set level, the thyristor control circuit 9 The thyristor is configured to transmit a start signal.

The thyristor control circuit 9 operates by a signal from the determination circuit 8 and is configured to be able to input a control signal to the thyristor switch 10 during a predetermined cycle of the system frequency. Accordingly, the thyristor switch 10 shifts from the off state to the on state while the control signal is input, and returns to the off state again when the control signal stops, and the system resumes the normal operation.

Further, in the embodiment shown in FIG. 1, a normally closed protective switch 1 is connected to a branch line 11 on the primary side of a thyristor switch 10.
2 is provided, and the control device 1 is configured separately for its control.
4 are installed. The protection switch 12 is provided with a closing coil (C
A lock mechanism 13 including a C) 13a and a trip coil (TC) 13b is provided, and is configured to be turned on and off by a control signal from the control device 14.

Further, on the secondary side of the protection switch 12, a second current detecting means 15 comprising a current transformer or the like is provided, and its signal line 15a is connected to the control device 14. Therefore, the lock mechanism 13 is driven by a signal from the second current detecting means 15.
Is released, and the protection switch 12 is opened to disconnect the branch line 11 from the distribution line 2.

Reference numeral 17 denotes a low-voltage line supplied from the distribution line 2 via the transformer 18, and supplies control power to the thyristor device 7 and the control device 14. The control device 14 can be configured to incorporate a power storage device (not shown), receive charging from the low voltage line 17, and display the open / closed state of the protection switch 12 by a lamp or the like. A lightning arrester 19 is provided on the branch line 11.

FIG. 2 shows an example of a mounting column of the apparatus of the present invention. The distribution line 2 is supported and supported by an insulator 22 erected on an arm 21a of a utility pole 21. The branch line 11 is connected to the distribution line 2 by a connector 23, is pulled into the protective switch 12 also suspended from the arm 21a from one bushing 24, is pulled out from the other bushing 25, and is suspended from the lower arm 21b. The thyristor device 7 from the bushing 26.

The lock mechanism 13 and the lightning arrester 19 are housed in the case 12a of the protection switch 12. Further, in the protective switch 12, a second current detecting means 15 is provided around the above-mentioned drawer-side bushing 25, and a signal line 15a is connected to the control device 14. Below the thyristor device 7, the control device 14 of the protection switch 2 is suspended from the lower arm 21c and installed. The low-voltage branch line 17a is drawn in from below, and the connection line 16 is pulled up along the utility pole. It is connected to the upper protection switch 12.

The operation of the embodiment constructed as described above is as follows. First, when the current detecting means 6 detects an overcurrent generated in the distribution line 2, the determination circuit 8 of the thyristor device 7 determines that a line fault has occurred due to the intensity level of the detection signal exceeding a set value, and the thyristor control circuit 9 To work.

The thyristor control circuit 9 inputs a control signal to the thyristor-type switch 10 for at least 1.5 cycles of the system frequency. The current is reduced, and the control signal returns to the on state again by the interruption. Therefore, the fault current in the distribution line 2 shifts to the branch line 11 while the thyristor switch 10 is on, and the arc discharge is extinguished in the distribution line 2 until the thyristor switch 10 returns to the off state. .

When the arc discharge is extinguished in the distribution line 2, when the accident occurs, the detection unit 3,
Even if 4 detects an accident current, the protection relay 5 stops opening the circuit breaker 1 until the set time, so that a power failure of the distribution line 2 is avoided.

If the arc discharge of the distribution line 2 is not extinguished even when the thyristor switch 10 is activated, the circuit breaker 1 of the substation H is opened to stop the line.

Further, in the embodiment, a normally closed protective switch 12 is provided on the branch line 11 on the primary side of the thyristor type switch 10 and a signal from a second current detecting means 15 provided on the secondary side thereof is used for this protection. Since the protection switch 12 can be opened, if the thyristor switch 10 is deteriorated,
The control device 14 controls the locking mechanism 13 to open the protection switch 12 by the leakage current of the thyristor switch 10 whose terminal is short-circuited. The thyristor switch 10
Is turned on even after the set time has passed, the circuit breaker 1 of the substation H is opened, so that the control device 14 uses the signal of the second current detecting means 15 for the set time or more (for example, 10 cycles). Is detected by the low-voltage line 17 supplied with power from the line, and the protection switch 12 is immediately controlled and opened. The obstacle does not spread.
Since the thyristor device 7 is separated from the distribution line 2 in this manner, there is an advantage that the power supply to the system is not hindered and that the thyristor device 7 can be inspected and repaired at any time.

[0020]

As described above, the present invention activates a thyristor switch at a branch point, eliminates an arc current from a line to prevent damage to the line or a power failure, and prevents a thyristor without interrupting power supply. Since the device can be separated from the track, there is an excellent effect on facility maintenance.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a front view showing an example of a mounting column of the device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Breaker of substation 2 Distribution line 6 First current detecting means 7 Thyristor device 10 Thyristor type switch 11 Branch line 12 Protective switch 15 Second current detecting means

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-220019 (JP, A) JP-A-59-206917 (JP, A) JP-A-59-206916 (JP, A) 130440 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02H 7/26 H02H 3/32-3/52 H02H 7/12 H03K 17/725-17/73

Claims (2)

(57) [Claims] A first current detecting means is provided in a distribution line,
A normally closed protection switch and an off-state thyristor switch are sequentially provided on the branch line of the distribution line to short-circuit the ends of the thyristor switch, and a second current detection is provided between the protection switch and the thyristor switch. Means for controlling the thyristor switch by judging that the signal level from the first current detecting means has exceeded a set value, and opening the protective switch by a signal from the second current detecting means. A protection device for a distribution line, characterized in that: 2. The protection switch according to claim 1, wherein the protection switch is opened by detecting that a short-circuit current flows for a set time or more, and that a circuit breaker of the substation is opened and the system is free of voltage. Distribution line protection device.