JPH05122922A - Circuit for sensing failure of device - Google Patents

Abstract

PURPOSE:To obtain a simple and cheap circuit for sensing the failure of a device, by sensing the short-circuit failure of the device through sensing that the width of the AC current application to a converter does not coincide with the width of the gate pulse of a GTO, in the self-excited converter of a current type, wherein the GTO's are used as semiconductor devices and its one arm is constituted of the series circuit comprising the GTO and a diode. CONSTITUTION:A self-excited converter of a current type is constituted of a series circuit comprising a transformer 1, AC capacitors 2, GTO's 3a-3f and diodes Da-Df, and is driven by gate signals fed from a gate timing control circuit 8. A circuit 11 for sensing the failure of a device is provided with an exclusive AND circuit for sensing that the width of the gate signal does not coincide with the width of the AC current application to the converter. When one of the GTO's 3a-3f fails by a short-circuit, the width of its gate signal does not coincide with the width of the AC current application to the converter, and a failure signal is generated from the circuit 11 for sensing the failure of a device, and a circuit 9 for switching on or off a breaker is operated, and further, a breaker 6 is open-circuited. Thereby, a simple and cheap circuit for sensing the failure of a device can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device failure detection circuit for a self-excited current source converter which is composed of self-turn-off devices.

[0002]

2. Description of the Related Art In recent years, a superconducting energy storage system (hereinafter referred to as SMES) has been used for storing energy by circulating a direct current in a superconducting coil to prevent pulse load such as nuclear fusion and electric power peak load. Research is in progress.
In addition to long-term power adjustment, SMES is a system that is stable if the converter connected to the power system is composed of self-extinguishing elements (for example, gate turn-off thyristor, hereinafter referred to as GTO). It is possible to have functions such as conversion and system reactive power compensation. FIG. 3 shows a circuit example of the SMES using a semiconductor element for the current source converter.

In FIG. 3, 1 is a transformer, 2 is an AC capacitor, and 3a to 3f are semiconductor elements, which constitute a self-excited converter. 4 is a superconducting coil, 5 is an AC current transformer,
Reference numeral 6 is a circuit breaker, 7 is an abnormality detection circuit, 8 is a gate timing control circuit for deciding on / off of a semiconductor element in response to a control command, 9 is a circuit breaker input disconnection circuit, and 10 is a system. Usually, in such a circuit, when the semiconductor element 3a has a short circuit failure, S phase-semiconductor element 3b-semiconductor element 3a-R phase,
Alternatively, a short-circuit current flows in the T-phase-semiconductor element 3c-semiconductor element 3a-R phase path, an overcurrent is detected by the AC current transformer 5 and the abnormality detection circuit 7, and the gate timing control circuit 8 detects the semiconductor element. The breaker 6 was shut off by the breaker on / off circuit 9 while the OFF signal was given to 3a to 3f.

By the way, when a GTO is used as a semiconductor element, the reverse voltage blocking capability of the GTO is very low. Therefore, when a diode is connected in anti-parallel to the GTO like a voltage source converter, there is a problem. However, there is a problem in configuring the current source converter as shown in FIG.

Therefore, a GT having a very low reverse voltage blocking capability
When configuring the current source converter with O, the diodes Da to Df are connected to the GTOs 3a to 3f as shown in the configuration example of FIG.
It is configured by connecting in series.

[0006]

However, in FIG. 4, even if the GTO 3a is short-circuited, there is a diode Da. Since a short circuit current does not flow in the path of the GTO 3a, there is a problem that a short circuit failure of the GTO 3a is not detected.

[0007] If the operation of the device is continued without detecting a failure, not only the control will not be performed normally, but also abnormal power will be supplied to the system, resulting in an adverse effect. For this reason, conventionally, the Japanese Examined Patent Publication No. 63-3620
As disclosed in No. 7, an element failure detector is provided in each of the GTOs 3a to 3f in FIG. 3 to detect an element failure. In such a conventional device, as many failure detectors as GTOs are required, so there is a problem that the cost becomes high and the structure becomes complicated. Therefore, it is an object of the present invention to provide an inexpensive and simple device failure detection circuit, which has been made to eliminate the above problems.

[0008]

In order to achieve the above object, the present invention uses a GTO as a semiconductor element,
In a self-excited current source converter having an arm formed by a series circuit of O and a diode, the positive side energization width of the alternating current of the self-excited current source converter and the gate pulse width of the GTO for determining the energization width A means for detecting a mismatch, and a means for detecting a mismatch between the current-carrying width on the negative side of the alternating current of the self-exciting current source converter and the gate pulse width of the GTO for determining the current-carrying width. To do.

[0009]

With the above configuration, when a short-circuit fault occurs in any of the GTOs constituting the self-excited current source converter, the conduction width of the AC current flowing through the GTO and the G
Since the gate pulse width of TO does not match, the element short-circuit failure can be detected.

[0010]

1 is a block diagram showing an embodiment of the present invention, in which the same parts as those in FIGS. 3 and 4 are denoted by the same reference numerals. In FIG. 1, reference numeral 11 is an element failure detection circuit that compares the gate signals Ga to Gf of the GTO with the output currents IR, IS and IT of the AC current transformer 5 and outputs a failure signal if they do not match. FIG. 2 is a time chart for explaining the operation of FIG. The present invention will be described below with reference to FIGS.

Normally, the operation is performed by the gate signal from the gate timing control circuit 8. FIG. 2 shows respective gate signals and AC current waveforms. In a normal state, the failure detection signal F is not output from the element failure detection circuit 11 because the gate signal width and the AC current conduction width match. If the GTO 3a is short-circuited at the time t0 for some reason, the output currents IR, IS, IT of the AC current transformer 5 after the time t0.
Has a waveform shown by a dotted line in FIG. On the other hand, the failure detection circuit 11 has an exclusive logic circuit that detects a mismatch between the width of the gate signal Ga and the energization width of the positive side of the alternating current IR, and the width of the gate signal Gb and the energization width of the negative side of the alternating current IR. is doing.
Further, although not shown, the alternating currents IS and IT are similarly constructed.

Therefore, when the GTO 3a has a short circuit failure after the time t0, the width of the gate signal Ga and the energization width of the positive side of the alternating current IR do not coincide with each other, and the failure signal F is generated from the element failure detection circuit 11. The breaker 6 is quickly released by the fault signal F. If the circuit breaker 6 is not released, the output currents IR, IS and IT of the AC current transformer 5 have waveforms like dotted lines.

[0013]

As described above, according to the present invention, G
Since the gate signal of TO is compared with the output current of the AC current transformer 5 for detecting the AC current of the converter, and the short circuit failure of the element is detected by the mismatch detection, the element failure detection is simple and inexpensive. A circuit can be provided.

[Brief description of drawings]

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

FIG. 2 is a time chart for explaining the operation of FIG.
To.

FIG. 3 is a configuration diagram of a superconducting energy storage system using a current source converter.

FIG. 4 is a basic configuration diagram of a self-excited current source converter using a GTO.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Transformer 2 ... AC capacitors 3a-3f ... GTO 4 ... Superconducting coil 5 ... AC current transformer 6 ... Breaker 8 ... Gate timing control circuit 9 ... Breaker on / off circuit 11 ... Element failure detection circuit F ... Failure detection Signal IR-IT ... AC current Ga-Gf ... Gate signal Da-Df ... Die auto

Claims (1)

[Claims] 1. A GTO is used as a semiconductor element, and the GT is used.
In a self-excited current source converter having an arm formed by a series circuit of O and a diode, the positive side energization width of the alternating current of the self-excited current source converter and the gate pulse width of the GTO for determining the energization width Device failure comprising means for detecting a mismatch and means for detecting a mismatch between the negative side energization width of the alternating current of the self-excited current source converter and the GTO gate pulse width for determining the energization width. Detection circuit.