JPH05168291A - Scherbius apparatus - Google Patents

Abstract

PURPOSE:To cut OFF a primary current by an AC breaker by turning OFF a GTO for constituting an inverter, and then discharging a capacitor of a DC circuit through a reactor. CONSTITUTION:When a three-phase short-circuiting fault occurs at a point A, a short-circuiting current flows at a primary side of a wound-rotor type induction machine (AM) 1. A primary current of the AM 1 abruptly becomes zero. It is detected by a short-circuiting accident detector 34, and GTOs 12-17 of an inverter 2 are turned OFF by a controller 36. Then, a GTO 40 is turned OFF, a discharge current becomes zero, and a capacitor 18 is charged. A thyristor 39 is turned ON, a current flows to a reactor 38, the capacitor 18 is discharged, and attenuated through a closed circuit of the thyristor 39, diodes 6-11 and the reactor 38. Then, a secondary voltage of the AM 1 abruptly becomes zero, and a DC component is superposed on the secondary current. An AC component is superposed on the primary current of the AM 1 by the DC component, and the primary current of the AM 1 can be cut OFF by an AC breaker.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a SELVIUS device which controls the secondary current of a wire wound induction machine with an inverter to perform variable speed control, and a three-phase short circuit accident occurs on the primary side of the wire wound induction machine. The present invention relates to a SELVIUS device capable of interrupting an accident current caused by an AC breaker.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram of a conventional SELVIUS device. In the figure, 1 is a winding type induction machine, 2 is an inverter for controlling the secondary current of the winding type induction machine 1, 3 is a DC power source for supplying a DC voltage to the inverter 2, and this DC power source is
The DC side terminal is commonly connected to the inverter DC side terminal,
The AC side terminal is composed of a power converter connected to the AC power supply system 5 or another power supply system. Reference numeral 4 is a circuit breaker for opening and closing the primary side of the wound-type induction machine 1, and 5 is the above-mentioned AC power supply system. The inverter 2 is, for example, diodes 6 to 11 which are bridge-connected, and a GTO which is inversely connected to the diodes 6 to 11.
12 to 17 and a capacitor 18. The power converter 3 is, for example, a diode 19 connected in a bridge.
~ 24 and GTO 25 to 30 connected in reverse parallel to this
And a transformer 33. The power converter 3 includes a discharge resistor 31 and a thyristor 32. When the DC voltage exceeds a rated value and reaches a predetermined value, the thyristor 32 is turned on to allow a current to flow through the discharge resistor 31 to generate a DC voltage. Protect it from becoming too large.

FIG. 4 is an operation waveform diagram for explaining the operation of the conventional SELVIUS device shown in FIG. In the figure, i1
Is the U-phase primary current of the wire wound induction machine 1, i2 is the V-phase primary current,
i3 is the W-phase primary current. i4 is the u-phase secondary current of the wire wound induction machine 1, i5 is the v-phase secondary current, and i6 is the w-phase secondary current.
v7 is the DC voltage of the inverter 2. i8 is the inverter 2
DC current of 6 to 11 as shown in FIG.
And GTO 12 to 17 and the current between the capacitor 18 and the bridge. i9 is a current flowing through the discharge resistor 31.

Prior to time t1, primary currents i1, i2, i3 of the frequency of the power supply system 5 flow through the primary side of the wound-rotor induction machine 1, while the inverter 2 controls the secondary side. Secondary currents i4, i5, and i6 having the slip frequency are generated. At time t1, if a three-phase short circuit accident occurs at point "A" shown in FIG. 3,
The primary side of the wound-type induction machine 1 has a short-circuit current i1, i2, i containing a DC component determined by the direction of the internal induced voltage vector at the time of short-circuit.
3 flows. This current contains a direct current component as shown in the figure, and is attenuated by the time constant of the primary circuit of the wound-rotor induction machine 1. Due to the DC component of the primary currents i1, i2, i3, an induced voltage of a frequency corresponding to the rotation speed of the rotor is generated on the secondary side of the wound-type induction machine 1, and secondary currents i4, i5, i6 flow. .. If the occurrence of a short-circuit accident is detected and the GTOs 12 to 17 of the inverter 2 are turned off, the secondary currents i4, i5, i6 are rectified by the diodes 6 to 11, and the current of the waveform shown at i8 is a DC circuit. Flow into. This current charges the capacitor 18 and the DC voltage v7 rises. At time t2, when the DC voltage reaches the preset protection level, the thyristor 32 is turned on to allow the discharge current i9 to flow and suppress the rise of the DC voltage v7.

[0005]

As described above, in the conventional SELVIUS device, the fault currents on the primary side of the winding type induction machine 1 caused by a three-phase short circuit fault are i1, i2, i3.
It becomes direct current as shown in. Generally, an AC circuit breaker for high voltage and large current does not have the ability to block DC, and blocks current at a point where the AC current crosses zero. Therefore, i1, i2,
It is not possible to cut off the direct current as shown by i3. In order to cut off such a current, it is necessary to apply a large-sized and expensive DC circuit breaker having an ability to extinguish a large current, which considerably impairs economical efficiency. Therefore, it is an object of the present invention to provide a SELVIUS device capable of interrupting a fault current with a small and inexpensive AC circuit breaker.

[0006]

To achieve the above object, the present invention relates to a primary winding connected to an AC power supply system via a circuit breaker, and a secondary winding connected to an AC side terminal of an inverter. A winding type induction machine, a capacitor connected between the DC side terminals of the inverter, the DC side terminal is commonly connected to the DC side terminal of the inverter, and the AC side terminal is the AC power supply system or In a SELVIUS device including a power converter connected to another power supply system, it is connected between a short-circuit fault detector that detects a three-phase short-circuit fault on the primary side of the winding-type induction machine and a DC terminal of the inverter. A series circuit of a switch having a rectifying function and a reactor, means for turning off a switching element that constitutes the inverter after the operation of the short-circuit accident detector, and means for turning on the switch having the rectifying function. It is characterized in that the.

[0007]

The present invention is constructed as described above,
When a three-phase short-circuit accident occurs, the GTO that composes the inverter 2 is once turned off, and then the charge of the capacitor of the DC circuit of the inverter is rapidly discharged through the reactor at a predetermined timing, and the inverter is discharged. By rapidly zeroing the voltage between the AC terminals of the, the DC component is superimposed on the secondary current of the wire wound induction machine, which causes the primary current of the wire wound induction machine to cross the zero point. Cut off the primary current with an AC circuit breaker.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, reference numerals 1 to 33 are the same as those of the conventional device described in FIG. 3, and the description thereof is omitted. Three
Reference numeral 4 is a short-circuit fault detector that detects a short-circuit fault instantaneously by detecting a rapid voltage drop when a three-phase short-circuit fault occurs on the primary side of the wound-rotor induction machine 1. Reference numeral 35 is a timer that generates a signal after a predetermined time has elapsed from the occurrence of a short circuit accident. Reference numeral 36 is a control circuit, and 37 is a voltage detector for detecting the DC voltage of the inverter. 38 is a reactor, 39 is a thyristor,
By turning on the thyristor 39, the reactor 38
The electric charge of the capacitor 18 is discharged via the. Reference numeral 40 is a GTO for turning on the discharge resistor 31.

The control circuit 36 responds to the signals of the short circuit accident detector 34 and the timer 35, and the signal of the voltage detector 37,
Means for turning off the GTOs 12 to 17 that constitute the inverter 2, means for turning on the thyristor 39, and the GTO 4
Although means for turning on 0 is provided, since these means are well known, details of the means will be omitted.

FIG. 2 is a waveform diagram for explaining the operation of the present invention. In the figure, i1 to i6, v7, i8 and i9 are waveforms at the same positions as i1 to i6, v7, i8 and i9 in the operation waveform diagram according to the conventional embodiment of FIG. Hereinafter, the operation of the present invention will be described in detail with reference to FIGS. 1 and 2.

When a three-phase short-circuit accident occurs at point "A" in FIG. 1 at time t1, the primary side of the wound-type induction machine 1 contains a DC component determined by the direction of the internal induced voltage vector at the time of short-circuit, Short-circuit currents i1, i2, i3 flow. This current is attenuated by the time constant of the primary circuit of the wound-rotor induction machine 1, as shown in the figure.
Due to the DC component of the primary currents i1, i2, i3, an induced voltage of a frequency corresponding to the rotation speed of the rotor is generated on the secondary side of the wound-type induction machine 1, and secondary currents i4, i5, i6 flow. When a three-phase short-circuit accident occurs, the voltage on the primary side of the wound-rotor induction machine 1 rapidly becomes zero. Therefore, the short-circuit accident detector 34 detects this rapid voltage drop, and the control circuit 36 causes the inverter 2 to operate. Turn off all GTOs 12-17. Secondary current i4, i5, i6
Is rectified by the diodes 6 to 11, and a current having a waveform indicated by i8 flows into the DC circuit. With this current, the capacitor 18 is charged and the DC voltage v7 rises. The DC voltage v7 is detected by the voltage detector 37, and when the DC voltage reaches the preset protection level at time t2, the control circuit 36
Signal turns on the GTO 40. When the GTO 40 is turned on, the discharge current i9 having a value determined by the resistance value of the discharge resistor 31
Flows and the rise of the DC voltage v7 is suppressed.

Next, at time t1, the timer 35 generates a signal after a fixed time has elapsed since the occurrence of the three-phase short circuit accident,
At time t3, the control circuit 36 turns off the GTO 40. When the GTO 40 is turned off, the discharge current i9 becomes zero, so that the capacitor 18 is charged by the DC current i8 and the DC voltage v7 rises. Due to the demagnetizing action at this time, the primary currents i1, i2, i3 of the wound-rotor induction machine 1 decrease like “B”,
Along with this, the secondary currents i4, i5, i6 also decrease. DC voltage v7
Is detected by the voltage detector 37, and at time t4,
When the DC voltage v7 reaches a preset protection level, a signal from the control circuit 36 turns on the thyristor 39. When the thyristor 39 is turned on, the current indicated by i10 flows through the reactor 38 and the electric charge of the capacitor 18 is discharged. Therefore, the DC voltage v7 decreases as shown in the figure, and becomes zero at time t5. The current i10 flowing through the reactor 38 is
Thyristor 39-diode 6 ... 11-reactor 38
It circulates in the closed circuit of and is attenuated by the loss in the closed circuit. At time t5, when the DC voltage v7 becomes zero, the voltage on the secondary side of the wire wound induction machine 1 also becomes zero.

As described above, the secondary voltage of the wound-rotor induction machine 1 rapidly becomes zero, and the direct current component is superimposed on the secondary currents i4, i5, i6. In the example of FIG. 2, a positive DC component is superimposed on the u-phase secondary current i4 as shown in “C”, and a negative DC component is superimposed on the v-phase secondary current i5 as shown in “D”. Minutes overlap,
As shown in "E", a negative DC component is superimposed on the w-phase secondary current i6. Due to this DC component, an AC component is superimposed on the primary currents i1, i2, i3 of the wound-rotor induction machine 1 as shown in the figure. After the time t6, the primary current i1, i2, i3 of the wound-rotor induction machine 1 can be cut off by the AC breaker.

In the above embodiment, the occurrence of a three-phase short-circuit accident is detected, and all GTOs constituting the inverter are once turned off to suppress the accident current from becoming excessively large, and then the reactor is used for the inverter. -The case of short-circuiting the DC circuit of the inverter was explained, but even if the DC circuit is short-circuited immediately after a short-circuit accident, the secondary voltage of the wound-type induction machine can be quickly reduced to zero. The primary currents i1, i2, i3 of the wound-rotor induction machine 1 can be cut off. Further, although the case where the thyristor is used as the switch for short-circuiting the DC circuit has been described, other switches such as a GTO and a transistor may be used. Also, as a thyristor,
A thyristor that self-ignites when the forward voltage exceeds a certain value, such as a VBO free thyristor, may be used.

Further, the case where the GTO is used as the switching element forming the inverter has been described.
The inverter may be configured using other switching means such as a transistor, another self-turn-off switching element, or a thyristor circuit having a forced commutation circuit.

[0017]

As described above, according to the present invention, when a three-phase short-circuit accident occurs on the primary side of a wound-rotor induction machine that constitutes a SELVIUS device, the GTO of the inverter is once turned off and then a predetermined timing is reached. Then, the electric charge of the capacitor of the DC circuit of the inverter is rapidly discharged through the reactor,
By rapidly reducing the voltage at the AC terminal of the inverter to zero, it is possible to superimpose a DC component on the secondary current of the wound induction machine. Therefore, a zero-cross point can be created in the fault current flowing through the primary side, so that a small and inexpensive AC circuit breaker can be applied as the circuit breaker on the primary side. Further, when a short-circuit accident occurs, the accident current can be suppressed by temporarily turning off the GTO of the inverter, so that the inverter device can be prevented from becoming large and expensive. As described above, according to the present invention, it is possible to provide a celius device capable of interrupting an accident current with a small-sized and inexpensive AC circuit breaker, so that its economical effect is remarkable.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a celius device according to an embodiment of the present invention.

FIG. 2 is a waveform diagram for explaining the operation of the present invention.

FIG. 3 is a block diagram of a conventional SELVIUS device.

FIG. 4 is a waveform diagram for explaining the operation of the conventional SELVIUS device.

[Explanation of symbols]

1 ... Winding type induction machine, 2 ... Inverter, 3 ... DC power supply, 4
... Circuit breaker, 5 ... Power supply system 6-11 ... Diode, 12-17 ... GTO, 18 ... Capacitor, 19-24 ... Diode, 25-30 ... GT
O, 31 ... Discharge resistor, 32 ... Thyristor, 33 ... Transformer, 34 ... Short circuit accident detector, 35 ... Timer, 36 ... Control circuit, 37 ... Voltage detector.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuyuki Abe 1-3-1, Uchiyuki-cho, Chiyoda-ku, Tokyo Within Tokyo Electric Power Company (72) Inventor Hirokazu Kaneko 1-3-3, Uchiyuki-cho, Chiyoda-ku, Tokyo Inside the Tokyo Electric Power Company (72) Inventor Ryoji Sugawara 6-15-1, Ginza, Chuo-ku, Tokyo Power source development Co., Ltd. (72) Inventor Takayoshi Sano 6-15-1 Ginza, Chuo-ku, Tokyo Open power source (72) Inventor Kazuo Hachiya Power source development, 6-15-1, Ginza, Chuo-ku, Tokyo Within (72) Inventor Hiro Uchino, No. 1 Toshiba-cho, Fuchu-shi, Tokyo Toshiba Fuchu factory

Claims (1)

[Claims] 1. A winding type induction machine in which a primary winding is connected to an AC power supply system via a circuit breaker, and a secondary winding is connected to an AC side terminal of an inverter, and a DC side terminal of the inverter. A SELVIUS device comprising a capacitor connected between and a power converter in which a DC terminal is commonly connected to a DC terminal of the inverter and an AC terminal is connected to the AC power system or another power system. A short-circuit fault detector for detecting a three-phase short-circuit fault on the primary side of the winding-type induction machine; a series circuit of a switch and a reactor having a rectifying function connected between the DC terminals of the inverter; and the short-circuit fault detection. A cellobius device comprising: a device that turns off a switching element that constitutes the inverter after the operation of the device; and a device that turns on a switch having the rectifying function.