JPS5967827A - Device for protecting dc transmission system ac/dc converter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protection device for an AC/DC converter in a DC power transmission system.

FIG. 1 shows a conventional example of this type of protection device.

In the figure, 10 is an AC/DC converter (forward converter) that performs a forward conversion operation, 20 is an AC/DC converter (inverse converter) that performs an inverse conversion operation, 21 is a phase control device, 30 is an AC system, and 31 is a converter. 32 is an AC breaker, 33 is a trip coil of the AC breaker 32, 34 is a manual operation switch for the AC breaker 32, 40 is an AC system fault detector, 50 is a DC system fault detector, 51 is a voltage Detector, 60 is a protection interlocking device, and P is an operating power source.

In this configuration, when a fault occurs in the AC system 30, the occurrence of the fault is detected by the AC system fault detector 40, and a fault signal fA is sent from the AC system fault detector 40 to the trip coil 3.
3, and the trip coil 33 is energized. When the AC breaker 32 is opened several cycles after the trip coil 33 is energized and load is cut off, the load capacitor (not shown) on the AC side of the inverter 20 is overcharged and an overvoltage is generated. The DC system failure detector 50 detects the overvoltage and sends the failure signal fo to the protection interlocking device 6.
0, and the stop command (signal) S is input from the protection interlocking device 60.
output. When this stop command S is inputted to the phase control device 21, a series of protection operations such as gate shifting and gate blocking are performed to stop the power conversion operation of the inverter 20. The same applies to the case where the manual operation switch 34 is turned on.

Since the conventional protection device is configured as described above, when a trip signal is output to the AC breaker 32, an overvoltage is generated from the AC converter 20 side, and then the gate shift and gate block are performed.Therefore, the power conversion operation is performed. Since the AC/DC converter 20 is stopped, there are drawbacks such as threatening the insulation of the equipment on the AC/DC converter 20 side.

This invention was made in order to eliminate the above-mentioned conventional drawbacks, and the present invention is to guide a failure signal outputted from an AC system failure detector to a protective interlocking device via a signal circuit and wait for the completion of tripping of an AC breaker. To provide a protection device for an AC/DC converter in a DC power transmission system, which can prevent the occurrence of overvoltage that would cause an AC breaker to open, by having the following configuration: With the goal.

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

In FIG. 2, the same reference numerals as in FIG. 1 indicate the same or corresponding parts. Reference numeral 70 denotes an auxiliary relay, which is energized to close the first a contact 70a1 and the second contact 70a2 when a failure signal fA outputted by the AC system failure detector 40 and a cutoff signal generated by turning on the manual switch 340 are generated. . When both A contacts 70a, 70a2 are closed, a trip signal m is sent from the operation power source P to the trip coil 33 via the σ-th A contact 70a1, and at the same time, the second
A signal n is supplied from the operating power source P to the OR element 80 via the a contact 70a. A failure signal fD output from the DC system failure detector 50 is also input to this OR element 80, and the output of the OR element 80 is supplied as a stop command signal S to the protection interlocking device 60.

In this configuration, when a failure occurs in the AC system 30, the auxiliary relay 70 is energized by the failure signal fA of the AC system failure detector 40, the signal n is input to the OR element 80, and the protective interlocking device 60 is activated. Then, the AC breaker 32 is opened as described above, so the AC breaker 32 is opened and the above-mentioned overvoltage is generated.
occurs and the power conversion operation of the AC/DC converter 20 is stopped within one cycle. This also applies when the manual operation switch 34 is turned on)).

As described above, according to the present invention, the fault signal of the AC and system fault detector is supplied to the protection interlocking device via the signal circuit, so that the AC breaker is opened and the AC The protective interlocking device is activated as soon as the above fault signal is generated and the conversion operation of the AC/DC converter is stopped, without waiting for a fault on the DC side to be detected on the DC side.
It is possible to prevent the occurrence of overvoltage caused by opening of an AC breaker, and prevent AC/DC converters and the like from being destroyed by overvoltage.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional protection device for an AC/DC converter in a DC power transmission system, and FIG. 2 is a block diagram of an embodiment of the protection device for an AC/DC converter in a DC power transmission system according to the present invention. In the figure, 20...AC/DC converter, 30...AC system, 32...AC breaker, 40...AC system fault detector, 60...protective interlocking device, 70...auxiliary relay , 70a+ + 70 a 2...A contact, 80
...Or element. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent Makoto Kuzuno - Procedural amendment (voluntary) 1. Display of incident Tokugan Sho 5-1177026 No. 2
・Invention (D name' + jr Protection device 3 for DC power transmission system AC/DC converters, relationship with the case of the person making the amendment Patent applicant address 112-3 Marunouchi 2-chome, Chiyoda-ku, Tokyo Name (601) Mitsubishi Electric Stock Company representative: Jinhachibe Katayama 4, agent address: 2-2-3-5 Marunouchi, Chiyoda-ku, Tokyo
, Column 6 of the detailed description of the invention in the specification subject to amendment, "AC converter 20J" on page 6, line 7 of the specification of contents of the amendment is corrected to "AC/DC converter 20."that's all

Claims (1)

[Claims] Equipped with a protective interlocking device that stops the conversion operation of the DC transmission system AC/DC converter in response to a failure signal from the DC side failure detector,
A protection device for an AC/DC converter that opens the AC breaker in response to a fault signal output by the AC system fault detection device, comprising a signal circuit that guides the fault signal of the AC system fault detector to the protection interlocking device. A protection device for AC/DC converters in DC transmission systems, which is a special feature of being attached.