JPH10174441A - Current form conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current form conversion device for reducing the short- circuit current capacity of a converter, miniaturizing the converter, and improving economical efficiency by breaking only a short-circuiting current, without breaking a main circuit current. SOLUTION: Assume that a U-phase GTO (self-arc-extinguishing element) 5a is damaged, a short-circuiting current flows through a path of an AC S phase → a GTO 5b → a fuse 9b → a fuse 9a →the self-arc-extinguishing element 5a → an AC R phase (dotted lines). The short-circuiting current is quickly limited by the fuses 9a and 9b, and a converter is protected from an excessive short-circuiting current. A main circuit current needs to flow, while protecting a short-circuiting current. Therefore, a diode 10b is connected in parallel with the fuse 9b, so that the main circuit current flows through the diode 10b instead of the fuse 9b, even if the fuse 9b blows out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current source converter for converting AC power into DC power.

[0002]

2. Description of the Related Art In recent years, superconducting energy storage devices (SMEs) have been developed.
A current-source converter using a self-extinguishing element (for example, a gate turn-off thyristor, hereinafter referred to as GTO) is used as an AC / DC converter for S) and DC transmission.

[0003] A conventional converter will be described with reference to FIGS. 7 and 8. 1 is an AC bus, 2 is an AC circuit breaker, 3 is a transformer, and 4 is a capacitor. When the self-extinguishing element interrupts current, it functions to absorb overvoltage generated by AC inductance. 5a to 5f are GTs constituting each arm.
O and 6 are loads having a large inductance. For example, SMES has an inductance of several hundred mH to several H in a superconducting coil. Reference numeral 7 denotes a control device for controlling the converter, which controls and protects the converter such as transmission of a gate pulse signal to the GTO 5a to 5f, transmission and reception of power to and from the system, and protection of the converter in the event of a failure. . Reference numeral 8 denotes a protection short-circuit switch, which is turned on when the converter fails, transfers the current of the converter to the short-circuit switch, and protects the converter with the fault current.

FIG. 8 shows an example of a gate pulse and an alternating current waveform of each phase during normal operation. Although each gate pulse has one pulse / period, the same applies to multiple pulses / period. The characteristic of the gate pulse of the current source converter is
The transmission is always performed so as to form a single current path when viewed from the load 6. That is, the high-voltage side arm (U, V, W) and the low-voltage side arm (X, Y, Z) each transmit a gate pulse to one of the arms. For example, U phase and Z
If the phase is rolling, the AC R-phase → U-phase arm (5a
GTO firing) → Load 6 → Z-phase arm (5f GTO firing) → AC T phase → AC R phase constitutes a single-cycle current path.

Further, alternating current waveforms (IR, IS, IT)
Focusing on, the waveform is intermittent. When the GTO turns off and interrupts the current, an overvoltage occurs due to the electromagnetic energy of the inductance in the AC circuit such as the impedance of the transformer 3. In such a current-source converter provided with a capacitor 4 to absorb the overvoltage, when a failure occurs in the converter and the protection of the converter is stopped, the gate block protection (current cutoff) is suddenly performed. Then, since the current of the DC circuit is also cut off, an overvoltage due to the load or the inductance of the DC circuit is also generated, which is superimposed on the overvoltage due to the inductance of the AC circuit, and the converter may be damaged by an abnormal overvoltage.

In order to correct this problem, in the conventional current source converter, the protection short-circuit switch 8 is turned on to secure a DC current supply path, and then a turn-off signal is given to the GTO to stop the converter from protection. doing.

[0007]

However, in the above-described conventional current source converter, when the self-extinguishing element fails, a short-circuit current flows through the arm, and this short-circuit current is suppressed only by the AC circuit inductance. Therefore, there is a problem that a large current of several tens kA to several hundreds kA or more occurs.

Further, since it is necessary to provide a device that can withstand this short-circuit current, there has been a problem that the size of the converter is increased and the price of the device is increased. In view of the above problems, the present invention realizes reduction of short-circuit current withstand capability, downsizing of the converter, and improvement of economy by interrupting only the short-circuit current without interrupting the main circuit current. It is an object of the present invention to provide a current source conversion device.

[0009]

In order to achieve the above object, the invention according to claim 1 comprises a self-extinguishing element in which the arm of each phase is bridged, and an on / off signal to the self-extinguishing element. A current source converter for converting AC power to DC power, comprising: a cutoff means connected in series to the self-extinguishing element; and a rectifier element connected in parallel to the cutoff means. It is characterized by having.

According to a second aspect of the present invention, when the interrupting means is interrupted, the control device sends an ON signal to the self-extinguishing elements of the upper and lower arms corresponding to the interrupted interrupting means. The off-signal is given to the self-extinguishing element of (1).

According to a third aspect of the present invention, in the control device, when the interrupting means is interrupted, the self-extinguishing element connected in series with the interrupted detecting signal of the interrupted interrupting means and the interrupted interrupting means. An ON signal is supplied to the self-extinguishing elements of the upper and lower pairs of arms corresponding to the interrupted interrupting means, and an OFF signal is applied to the other self-extinguishing elements based on an AND condition with the ON signal of the above. I do.

The invention according to claim 4 is characterized in that a protection short-circuit switch is provided on the DC power side. According to a fifth aspect of the present invention, there is provided a first self-arc-extinguishing element in which the arm of each phase is bridged, and a control device for supplying an on / off signal to the self-arc-extinguishing element. A current source conversion device for converting power into electric power, comprising: a cutoff means connected in series to the first self-extinguishing element; and a second self-extinguishing element connected in parallel to the interrupting means. Features.

According to a sixth aspect of the present invention, there is provided a first self-extinguishing element in which the arm of each phase is bridged, and a control device for applying an on / off signal to the self-extinguishing element. In a current source converter for converting electric power into DC power, a shutoff means connected in series to the first self-extinguishing element, a second self-extinguishing element and a rectifier connected in parallel to the shutoff means And a series circuit comprising:
The invention according to claim 7 is characterized in that the breaking means is a fuse, and the rectifying element is a diode.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. The same components as those of the conventional example in FIG. 7 are denoted by the same reference numerals, and description thereof will be omitted.
9a to 9f are semiconductor element protection high-speed current limiting fuses, which are connected in series with self-extinguishing elements (for example, GTO) 5a to 5f. Diodes 10a to 10f are connected in parallel to the fuses 6a to 6f, respectively.

Next, the current path will be described. When the converter is operated by the gate pulse shown in FIG. 8 and the V-phase and the Z-phase are ignited, for example, AC S-phase → GTO5b → Fuse 9b → Load 6 → GTO5f → Fuse 9f → AC T
The main circuit current is flowing through the phase path (solid line in FIG. 1).

Here, for some reason, the U-phase GTO 5a
Is assumed to be broken, the short-circuit current becomes AC S-phase → GT
O5b → Fuse 9b → Fuse 9a → Self-extinguishing element 5a → AC R-phase flow (dotted line in FIG. 1). The short-circuit current is limited at high speed by the fuses 9a and 9b to protect the converter from an excessive short-circuit current.

The main circuit current needs to flow while protecting the short-circuit current. Therefore, a diode 10b is connected in parallel with the fuse 9b so that the main circuit current flows via the diode 10b instead of the fuse 9b even if the fuse 9b is blown.

As described above, according to the present embodiment, the GTO
Even if the arm breaks and an arm short-circuit accident occurs, the fuse can limit the short-circuit current at high speed to protect the converter from excessive short-circuit current, and the diode connected in parallel with the fuse can reduce the current path of the main circuit current. In order to ensure, there is no overvoltage due to the interruption of the main circuit current.
Damage to the GTO of the other healthy arm and damage to the transducer will not occur.

A second embodiment of the present invention will be described with reference to FIG. This embodiment has the same configuration as the first embodiment, and the solid line A in FIG. 2 is the path of the main circuit current. As shown in the first embodiment, the following operation is performed after the main circuit current flows through the diode 10b instead of the fuse 9b even if the fuse 9b is blown.

Detecting the blow of the fuses 9a and 9b, a turn-on gate signal is supplied to GTOs 5c and 5f of the sound upper and lower symmetrical arms, and a turn-off gate signal is supplied to GTOs 5a, 5b, 5d and 5e.

As a result, the main circuit current is GTO5c → fuse 9c → load 6 → GTO5f → fuse 10f.
This is a so-called WZ phase bypass pair operation (solid line B in FIG. 2). Therefore, the time during which the current flows through the diode 10b is short, and the rating of the diode can be reduced.

As described above, according to the present embodiment, there is no occurrence of overvoltage due to interruption of the main circuit current, damage of the converter due to overvoltage does not occur, and further, the rating of the diode connected in parallel with the fuse is reduced. Can be selected,
The converter can be made compact.

A third embodiment of the present invention will be described with reference to FIG. This embodiment has the same configuration as the first embodiment, and the main circuit current (solid line A in FIG. 3A) when the GTO 5a is broken is replaced with the fuse 9b even if the fuse 9b is blown. It flows through the diode 10b. However, in the present embodiment, the control device 7
FIG. 3 (b) shows a condition for transmitting a gate pulse from the first arm and an on-gate signal for the upper and lower pairs of the arm according to an AND condition between the on-gate signal of the arm and the fusing detection signal of the high-speed current limiting fuse of the arm. It sends out a signal.

When the fuses 9a and 9b are blown, an on-gate signal is sent to the VTO GTO 5b. Here, based on the block diagram of the transmission condition of FIG. 3A, an on-gate signal is given to the GTO 5e of the Y arm and the GTO 5e of the Y arm is fired according to the condition of the blow signal of the fuse 9b and the ON signal of the GTO 5b. . Furthermore, GTOs 5a, 5c, and 5 other than GTOs 5b and 5e
d and 5f are supplied with a turn-off gate signal, and GTO
5a, 5c, 5d and 5f are turned off.

As a result, the main circuit current is GTO 5b → diode 10b → load 6 → GTO 5e → fuse 10e
, The so-called VY phase bypass pair operation (solid line B in FIG. 2).

As described above, according to the present embodiment, no overvoltage is generated due to the interruption of the main circuit current, and the GTO of another sound arm or the converter is damaged due to the overvoltage. Further, since the blow of the fuse is detected and the main circuit current is immediately shifted to the bypass pair operation of the upper and lower arms, the operation of the current source converter can be stopped safely and at high speed.

FIG. 3B is a block diagram of the U and X phases, but the same can be applied to the V, Y, W, and Z phases. A fourth embodiment of the present invention will be described with reference to FIG.

This embodiment has the same configuration as that of the first embodiment. When the GTO 5a is damaged, the main circuit current (solid line A in FIG. 4) is used instead of the fuse 9b even if the fuse 9b is blown. It flows through the diode 10b.

This embodiment further includes a fuse 9a,
9b, the protection short-circuit switch 8 is turned on, and then a turn-off gate signal is sent to the GTOs 5a to 5f.
Turn off all GTOs.

As a result, the main circuit current flows back between the protection short-circuit switch 8 and the load 6 bypassing the converter (solid line B in FIG. 4). As described above, according to the present embodiment, the main circuit current is immediately commutated to the protection short-circuit switch provided in the DC circuit by detecting the blowing of the fuse.
The current source converter can be safely and quickly shut down.

A fifth embodiment of the present invention will be described with reference to FIG. In this embodiment, the diodes 10a to 10f connected in parallel to the fuses 9a to 9f in the first embodiment are replaced with self-extinguishing elements (for example, GTs).
O) 11a to 11f. The main circuit current (solid line in FIG. 5) when the GTO 5a is broken is determined by the fuse 9b.
Is blown through the GTO 11b instead of the fuse 9b. Furthermore, GTO5a ~
It is also possible to give the same gate pulse to each of 5f and GTOs 11a to 11f.

As described above, according to the present embodiment, no overvoltage is generated due to the interruption of the main circuit current, and the GTO of another sound arm and the converter are not damaged due to the overvoltage. , And G in each arm
Even if the TOs 5a to 5f are damaged, the operation can be continued as it is.

A sixth embodiment of the present invention will be described with reference to FIG. This embodiment is different from the fifth embodiment in that the fuses 9a to 9f are connected to the diodes 10a to 1f.
0f and self-extinguishing type elements (for example, GTO) 11a to 11f
Are connected in parallel. As in the fifth embodiment, GTOs 5a to 5f and GTO 11a to
11f is given the same gate pulse.

As a result, according to the present embodiment, the GTO5
Even if a to 5f are damaged and an arm short-circuit accident occurs, the converter can be protected from an excessive short-circuit current by the fuses 9a to 9f and the GTOs 11a to 11f serve as a current path of the main circuit current. There is no overvoltage caused by the interruption, and the converter can be prevented from being damaged due to the overvoltage, so that the reliability of operation continuity is improved as compared with the fifth embodiment.

[0035]

As described above, according to the present invention, only the short-circuit current is interrupted without interrupting the main circuit current, so that the short-circuit current withstand capability of the converter is reduced, the converter is downsized, and the economy is improved. Can be provided.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a current source conversion device according to a first embodiment of the present invention.

FIG. 2 is a conceptual diagram of a current source conversion device according to a second embodiment of the present invention.

FIG. 3 is a conceptual diagram of a current source conversion device according to a third embodiment of the present invention.

FIG. 4 is a conceptual diagram of a current source conversion device according to a fourth embodiment of the present invention.

FIG. 5 is a conceptual diagram of a current source conversion device according to a fifth embodiment of the present invention.

FIG. 6 is a conceptual diagram of a current source conversion device according to a sixth embodiment of the present invention.

FIG. 7 is a configuration diagram of a conventional current source conversion device.

FIG. 8 is a waveform diagram showing a gate pulse and an alternating current waveform of the current source conversion device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 AC bus 2 AC circuit breaker 3 Transformer 4 Capacitor 5, 11 GTO 6 Load 7 Controller 8 Protection short circuit switch 9 Fuse 10 Diode

Claims (7)

[Claims] 1. A current source for converting an AC power to a DC power, comprising: a self-extinguishing element having a bridge configuration of each phase arm; and a control device for supplying an ON / OFF signal to the self-extinguishing element. A current source conversion device, comprising: a converter connected in series to the self-extinguishing element; and a rectifier connected in parallel to the interrupter. 2. The self-turn-off device according to claim 2, wherein when the shut-off means shuts off, the control device sends an ON signal to the self-extinguishing elements of the upper and lower pair of arms corresponding to the shut-off means, and the other self-extinguishing elements. 2. The current source conversion device according to claim 1, wherein an off signal is supplied to the current source. 3. The control device according to claim 2, wherein, when the shutoff means is shut off, an AND signal of a shutoff detection signal of the shutoff means and an ON signal of a self-extinguishing element connected in series to the shutoff means. 2. The self-arc-extinguishing element of the upper and lower pair of arms corresponding to the interrupted interrupting means is provided with an ON signal and the other self-extinguishing element is supplied with an OFF signal based on a condition. Current source converter. 4. The current-source converter according to claim 1, wherein a protection short-circuit switch is provided on the DC power side. 5. A first self-extinguishing element in which the arm of each phase is bridged, and a control device for supplying an on / off signal to the self-extinguishing element, converts AC power into DC power. A current source conversion device comprising: a shut-off means connected in series to the first self-extinguishing element; and a second self-extinguishing element connected in parallel to the interrupting means. Current source converter. 6. A first self-extinguishing element in which the arm of each phase is bridged, and a control device for supplying an on / off signal to the self-extinguishing element, converts AC power into DC power. A current source conversion device comprising: a shutoff means connected in series to the first self-extinguishing element; and a series circuit comprising a second self-extinguishing element and a rectifying element connected in parallel to the interrupting means. A current source conversion device, comprising: 7. The current-source converter according to claim 1, wherein said interrupting means is a fuse, and said rectifying element is a diode.