JPH1042461A - Capacitor protective device for dc filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitor bank for DC filter used for the DC power source of a power converter which can make a system to be operated continuously, even when a failure occurs in a capacitor by only disconnecting the defective capacitor from a power source circuit by using a failure detecting signal without stopping the entire system. SOLUTION: A fuse 12 and a switch 13 are connected in series with a capacitor 11, and a commutation circuit 2 composed of a commutation capacitor 21, a charging power source 3 and an inductance 24 is connected to both ends of the fuse 12, and then a semiconductor switch element or switch 15 which is conducted by means of the failure detecting signal of the capacitor 21 is connected in series between the fuse 12 and circuit 2, so that the capacitor 11 can be disconnected from the power source 3 when a failure occurs in the capacitor 11 by fusing the fuse 12 by making a large oscillating current to flow into the fuse 12 by using the failure detecting signal of the capacitor 21 and, at the same time, triggering the switch by using the operating signal of the fuse 12.

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 capacitor bank for a DC filter used on the DC side, such as a large-capacity self-excited inverter device used mainly in a reactive power compensator or a frequency converter. is there.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, a circuit breaker on a power supply side of a power converter is opened by a failure detection signal of a capacitor.

[0003]

As described above, conventionally, when a capacitor has failed, a system in which the power supply side of the power converter is opened and the power converter is completely stopped has been used, but several to several tens of MVA have been used. In the large-capacity converter, the DC filter capacitor bank is composed of several tens of capacitors, and it is unreasonable considering the effect of the failure of one of these capacitors to stop the entire system.
There is a strong demand that only the faulty capacitor be separated and the operation continued.

For this reason, there is a case where a DC fuse is attached to each capacitor in a relatively small-capacity converter having a relatively low DC voltage, but when a large-capacity DC voltage is high, Since there was no DC fuse available for this, there was no other way but to stop the entire system as described above.

[0005]

As a method of detecting an internal failure of a capacitor, a method of detecting imbalance of current or voltage or a method of detecting an increase in internal pressure of a case has been considered and put to practical use. DC capacitors have difficulty blocking high voltage DC current. For this reason, the present invention employs a method of generating a large oscillating current by using a commutation circuit using a discharge current of a capacitor, thereby blowing a fuse and generating a current zero point to interrupt the current.

That is, according to the present invention, the capacitor 11
A DC filter capacitor bank 1 of a power converter, comprising a fuse 12, a switch 13, a semiconductor switching element or switch 15, and a commutation circuit 2 including a commutation capacitor, an inductance, and a charging power source. Is a capacitor having a function of detecting an internal failure and generating a signal, and the capacitor 11 and the switch 13
And a commutation circuit 2 comprising a commutation capacitor, an inductance and a charging power supply.
Are connected in parallel, and a semiconductor switching element or switch 15 through which commutation current flows according to a signal for detecting an internal failure of the capacitor is connected in series between the fuse 12 and the commutation circuit 2, and the capacitor When an internal failure occurs in the fuse, the fuse is blown by a large oscillation current generated from the commutation circuit through the semiconductor switching element or the switch through which the commutation current flows, and the current is cut off. And a switch for tripping the switch to close the switch to trip the switch.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The DC filter capacitor protection device of the present invention reliably disconnects this capacitor from the power supply in accordance with the capacitor internal detection signal. Only the failed capacitor is disconnected, and the entire system operates without any trouble. Can be continued.

[0008]

Embodiment 1 FIG. 1 shows an embodiment of the configuration of a capacitor protecting device for a DC filter according to the present invention. In FIG. 1, reference numeral 1 denotes a DC filter capacitor bank used for a DC power supply such as a power converter, 11 denotes a capacitor constituting the DC filter capacitor bank, 12 denotes a fuse connected in series to the capacitor, and 13 denotes a switch. is there. A commutation circuit 2 supplies a large current to the fuse. The commutation circuit 2 includes a commutation capacitor 21, a rectifier circuit 22, a charging resistor 23, and an inductance 24, and is supplied with power from the AC power supply 3. Reference numeral 15 denotes a semiconductor switching element such as a thyristor that is turned on by an internal failure detection signal of the capacitor 11. Reference numeral 4 denotes a power supply for tripping the switch 13, and supplies a current to the trip coil of the switch 13 by closing the switch 16.

When an internal failure occurs in the capacitor 11,
The thyristor 15 is turned on by this detection signal, and the accumulated charge of the commutation capacitor 21 is discharged to the fuse 12 through the inductance 24, so that a large oscillating current flows. The fuse is blown by the current energy, the switch 16 is closed by the operation signal of the fuse, the trip coil of the switch 13 is excited by the trip power supply 4, the switch 13 is opened, and the fault capacitor 11 is opened. Disconnected from the power supply.

[0010]

According to the protection device for a DC filter capacitor of the present invention, only a failed capacitor can be disconnected from a power supply by a failure detection signal without stopping the entire system due to failure of one capacitor. Since the operation can be continued, there is a great effect on improving the reliability of the system without affecting the system.

[Brief description of the drawings]

FIG. 1 is a connection diagram showing one embodiment of the configuration of a DC filter capacitor protection device of the present invention.

FIG. 2 is a connection diagram showing one embodiment of a conventional application method of a DC filter capacitor protection device.

[Explanation of symbols]

 1: DC filter capacitor bank 2: Commutation circuit 3: AC power supply 4: Tripping power supply 5: Power converter 6: Power supply circuit breaker 11: Capacitor 12: Fuse 13: Switch 13: Semiconductor switching element or switch Container 16: Switch 21: Commutation capacitor 22: Rectifier circuit 23: Charging resistor 24: Inductance

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication location H02M 7/06 8726-5H H02M 7/06 G 7/48 8110-5H 7/48 M (72) Inventor Koji Morita Nichicon Co., Ltd., 3rd floor of 4 Uehara Bldg., 191 Nakabori-cho, 1st line, Oike-dori Karasuma Higashi-iri, Nakagyo-ku, Kyoto-shi, Kyoto

Claims (3)

[Claims] A capacitor (11) and a fuse (1)
2), a switch (13), a semiconductor switch or a switch (15), a commutation capacitor, a commutation circuit (2) including an inductance and a charging power supply, and a capacitor bank for a DC filter of a power converter. (1)
Each of the capacitors (11) is a capacitor having a function of detecting an internal failure and generating a signal, and includes a capacitor (1).
A fuse (12) connected in series between 1) and a switch (13) and a commutation circuit (2) composed of a commutation capacitor, an inductance and a charging power supply are connected in parallel. A semiconductor switching element or switch (15) that passes a commutation current in response to a signal for detecting an internal failure,
A series connection is made between the fuse (12) and the commutation circuit (2). When an internal failure occurs in the capacitor, the fuse is blown by a commutation current, and a trip circuit of the switch is operated by an operation signal of the fuse. A protective device for a DC filter capacitor, characterized in that the switch is closed and the switch (13) is tripped. 2. The protection device for a DC filter capacitor according to claim 1, wherein the semiconductor switching element or switch connected in series between the fuse and the commutation circuit is a thyristor or a transistor that is turned off by a gate signal. 3. The protection device for a DC filter capacitor according to claim 1, wherein the semiconductor switching elements or switches respectively connected in series between the fuse and the commutation circuit are electromagnetic switches that are closed by a signal current.