JPH04207996A - Controlling method for scherbius equipment - Google Patents

Abstract

PURPOSE:To cut out an accident current when cutting out the current of a short-circuit accident occurred at the primary side of a wound-rotor induction machine by turning on/off a switching element in response to the value of secondary current, superimposing a DC component to the secondary current and creating a zero cross point for the primary current. CONSTITUTION:When a U-phase secondary current becomes larger than zero, the output of an AND circuit 46 becomes '1' and GTO 15 is turned on. At this time, the secondary current flows from the secondary U-phase to GTO15 diode 10 returning to the secondary V-phase thereby acting in the direction for increasing the secondary current, so that U-phase current is shifted to the positive direction. Then, when the U-phase secondary current reaches the value of GTO controllable current, then U-phase GTO ON signal becomes '0' and GTO 15 is turned off. The U-phase secondary current and W-phase secondary current are shifted to the positive side, and the V-phase secondary current is shifted to the negative side. In this way, a zero cross point can be created in the primary current by superimposing a DC component to the secondary current of a wound-rotor induction machine 1.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention provides a Cerbius device for controlling the secondary current of a wound induction machine using an inverter. The present invention relates to a method of controlling an inverter when using a circuit breaker to interrupt the current caused by a short-circuit accident.

(Prior Art) FIG. 5 is a block diagram of a conventional embodiment. In the figure, 1
2 is an inverter that controls the secondary current of the wound induction machine 1; 3 is a DC power source that supplies DC voltage to the inverter 2; 4 is a circuit breaker on the primary side of the wound induction machine 1; 5
is the power supply system. The inputter 2 includes, for example, diodes 6 to 11, CTOs 12 to 17, and a capacitor 18.

In addition, the DC power supply 3 includes diodes 19 to 24, GT025
~30. It is composed of a transformer 33. GT for DC power supply 3
It includes O31 and discharge resistor 32, and when the DC voltage reaches a predetermined value exceeding the rated value, GTO31 is turned on and current flows through the discharge resistor 32, and the DC voltage is controlled so as not to become excessive. Ru.

FIG. 6 is an operating waveform diagram according to a conventional embodiment. In the figure, (1> is the U-phase current of the wound induction machine 1, (2)
is V-phase secondary current, (3) W-phase secondary current, (4) is U-phase secondary current, (5) is V-phase secondary current, (6) is W-phase secondary current, (7) is The DC voltage of the inverter 2, (8) is the current flowing through the discharge resistor 32, and (9) is the DC current flowing out from the inverter 2.

Before time t1, the primary current (1) of the wound induction machine 1 is
(2) and (3) are alternating currents at the frequency of the power supply system 5, while secondary currents (4), (5), and (6) are alternating currents at the slip frequency controlled by the inverter 2. Time t
1, if a three-phase short circuit accident occurs at point "A" in Figure 5, an excessive short circuit containing a DC component determined by the direction of the internal induced voltage vector at the time of the short circuit will occur on the primary side of the wound wire induction machine 1. A current flows, and this current is attenuated by the time constant of the primary circuit of the wound induction machine 1. - Wound induction machine 1 due to the direct current component of the secondary current
An induced voltage with a frequency corresponding to the rotational speed of the rotor is generated on the secondary side of the rotor. Assuming that GTOs 12 to 17 of inverter 2 are turned off at the same time as a short-circuit accident, secondary currents (4), (5), <
6) is rectified by diodes 6 to 11 and flows into the DC circuit with a waveform as shown in (9). This current increases the DC voltage (7). At time t2, when the GTO31 is turned on because the DC voltage has reached the upper limit value, the discharge current (
8) flows and controls the increase in voltage (7).

When the DC voltage reaches the lower limit value at time t3, GTO31
Turn off.

(Problems to be Solved by the Invention) In the conventional configuration described above, when the circuit breaker 4 interrupts an excessive current generated due to a short circuit accident, an excessive DC current (L ), (2), (3
) is necessary. Generally, high-voltage, large-current AC circuit breakers do not have the ability to interrupt DC.

Therefore, it is necessary to use a large and expensive DC circuit breaker, which significantly impairs economic efficiency.

In order to eliminate the drawbacks of the conventional Servius device described above, the present invention superimposes a DC component on the secondary current (4) (5) (6) of the wound induction machine l using the inverter 2 after a short circuit accident occurs. and -order current (1), (2), (3
) by creating a zero-crossing point at the AC circuit breaker.

[Structure of the Invention] (Means and Effects for Solving the Problems) In the present invention, after a short-circuit accident occurs, the GTO of the inverter is turned off, and the secondary current of the wound induction machine flows through the diode to the DC circuit. When the secondary current is detected, the GTO is turned on for a short time only in a predetermined polarity range when the secondary current value is less than the controllable current of the GTO, and the secondary winding of the wound induction machine is short-circuited for a short time. A loop is created, the secondary current is increased only in a predetermined direction, and a DC component is superimposed on the secondary current.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. 1st
The figure is a configuration diagram of an embodiment of the present invention. In the diagram 1~
Reference numeral 33 is the same as the same symbol in the configuration diagram of the conventional embodiment described in FIG. 34 is a short circuit detector that detects a voltage drop and detects a short circuit accident occurring on the primary side of the wound induction machine 1 at high speed; 35 is a current detector that detects the secondary current of the wound induction machine 1; 36 is a current detector that detects a secondary current of the wound induction machine 1; It's a timer. 37 is a logic circuit,
A GTO switching signal 38 for the inverter 2 is generated in accordance with the secondary current value detected by the current detector 35.

FIG. 2 is a detailed configuration diagram of the logic circuit 37 shown in FIG.
39 is a polarity inverter, 40 to 45 are comparators, 46 to 48 are AND circuits, 4 are short-circuit fault signals, 50 is U-phase secondary current, 51 is V-phase secondary current, 52 is W-phase secondary current , 53 is G
TO controllable current, 54 is a zero reference, 55 is a U-phase GTO on signal, 56 is a V-phase GTO on signal, and 57 is a W-phase GTO on signal.

FIG. 3 is a waveform diagram showing the effect of the present invention.

In the figure, (1) to (9) are waveforms at the same locations as (1) to (9) described in the operating waveform diagram of the conventional example in FIG. (10) is the waveform of the U-phase GTO ON signal 55 in FIG.
During the period of "1", the U-phase GTO 15 in Figure 1 is turned on. (11
) is the current waveform flowing through the U-phase GTO 15. Similarly (
12) is the waveform of the V-phase GTO on signal 56, which turns on the V-phase GTO 13 for a period of "1".

(13) is a current waveform flowing through the V-phase GTO 13.

(14) is the waveform of the W-phase GTO on signal 57, which turns on the WmGTO 17 for a period of "1". (15) is W-phase GTO
This is the waveform of the current flowing through the circuit 17.

At time t1, when a three-phase short circuit accident occurs at point "A" in Figure 1, the primary side of the wound wire induction machine 1 has an excessive DC component that is determined by the direction of the internal induced voltage vector at the time of the short circuit. Currents (1) to (3) flow, and excessive currents (4) to (6) also flow to the secondary winding that is electromagnetically coupled to the -order winding.

A short circuit on the primary side of the wound induction machine 1 is detected by a short circuit fault detector 34.
, and once all GTOs 12 to 17 of inverter 2 are turned off.

When a short circuit is detected by the short circuit accident detector 34, the four short circuit accident signals shown in FIG. 2 become "1", and the AND circuits 55 to 57
The third input signal becomes "1".

Next, the comparator 40 compares the GTO controllable current 53 and the U-phase secondary current 50, and the output of the comparator 40 becomes "1" in a range smaller than the U-phase secondary current 50 or the GTO controllable current 53. Become. The comparator 41 compares the zero reference 54 and the U-phase secondary current 50, and the output of the comparator 41 becomes "1" in a range where the U-phase secondary current 50 is greater than zero. Comparator 40 and comparator 41
The output of is input to the AND circuit 46, and the U-phase secondary current 5
In a range where 0 is greater than zero and smaller than the controllable current 53 of the GTO, all the inputs of the AND circuit 46 become 1'' and its output becomes ``1''.

Similarly, in the comparator 42, the zero reference 54 and the V-phase secondary current 51
are compared, and the output of the comparator 42 becomes "1" within a range where the V-phase secondary current 51 is smaller than zero.

The comparator 43 compares the negative value of the GTO controllable current 53 and the V-phase secondary current 51, and the output of the comparator 43 is in the range where the V-phase secondary current 51 is larger than the negative value of the GTO controllable current 53. It becomes “1”. The outputs of the comparators 42 and 43 are input to an AND circuit 47, and in the range where the V-phase secondary current 51 is greater than the negative value of the GTO controllable current 53 and less than zero, all inputs to the AND circuit 47 are "1" and its output becomes "1".
"become.

Similarly, the comparator 44 compares the GTO controllable current 53 and the W-phase secondary current 52, and if the W-phase secondary current 52 is smaller than the GTO controllable current 53, the output of the comparator 44 will be "1".
become. In the comparator 45, the zero reference 54 and the W-phase secondary current 52
are compared, and the output of the comparator 45 becomes "1" in a range where the W-phase secondary current 52 is greater than zero. Comparator 44 and comparator 4
The outputs of the AND circuit 48 are input to the AND circuit 48, and in the range where the W-phase secondary current 52 is larger than zero and smaller than the controllable current 53 of the GTO, all the inputs of the AND circuit 48 become "1" and the output becomes " It becomes 1″.

At time t1, immediately after a three-phase short circuit accident occurs at point "A," the V-phase secondary current 51 is in a range greater than the negative value of the GTO controllable current 53 and less than zero. Output 56 (v-phase GTo on signal (12))
1" and turns on GTO1B. Also, the W-phase secondary current 52 is in a range larger than zero and smaller than the GTO controllable current 53. Therefore, the output 57 of the AND circuit 48 (
The W-phase GTo on signal (14)) becomes “1”, and the GTO
Turn on 17. When GTO13 and GTO17 are not turned on, the secondary current flows from the secondary W phase of the wound induction machine 1 to the diode 8 - the positive side of the DC current 3 - the negative side of the DC power supply 3, as shown by the dotted arrow in Fig. 1. - Diode 10 - The current flows through the path returning to the secondary V phase, and the DC power supply 3 acts in a direction to suppress the increase in secondary current.

However, by turning on GTO13 and GTO17, the secondary current flows through the wound induction machine 1 as shown by the solid arrow.
Flows from the secondary W phase of GTO 17 - the negative side of the DC power supply 3 - the positive side of the DC power supply 3 - GTO 13 - in a path returning to the secondary V phase,
Since the DC power supply 3 acts in the direction of increasing the secondary current, it is possible to shift the ■ phase current in the negative direction and the W phase current in the positive direction. At time t4, W-phase secondary current 5
2 reaches the controllable current 53 of the GTO, the W-phase GTO on signal (14) becomes "O" and turns off the GTO 17. At this time, the secondary current of the wound wire induction machine 1 flows from the secondary W phase to the diode 8 → GTO 13 → back to the secondary V phase, and also acts in the direction of increasing the secondary current.
The V-phase current can be shifted in the negative direction. At time t5, the V-phase secondary current 51 becomes the controllable current 53 of the GTO.
When the negative value of
'' and turns off GTO13.

Next, at time t6, when the U-phase secondary current 50 becomes larger than zero, the output 55 of the AND circuit 46 (U-phase GTO on signal (1, O')) becomes "]", turning on the GTO]5. At this time, the secondary current flows from the secondary U-phase through the GTO15-diode]0 to the secondary V-phase, and also acts in the direction of increasing the secondary current, so the U-phase current is You can do something like shift it in the direction of . At time t7, U
When the secondary current 50 reaches the value of the GTO's arbitrary a current 53, the phase GTO on signal (10) becomes 0, and the GTO
Turn off 15. Below, it acts in the same way, and the U-phase secondary current 50
The W-phase secondary current 52 is shifted to the positive side as shown in the waveforms (4) and (6> in Figure 3), and the V-phase secondary current 51 is shifted to the negative side as shown in the waveform (5). In this way,
Wound induction machine 1. Secondary current (4) , (5) ,
By superimposing a DC component on (8), the negative current (
Zero cross points can be created at 1), (2), and (3).

FIG. 4 is a waveform diagram showing the operation of another embodiment of the present invention. In the figure, (1) to (15) are waveforms at the same locations as (1) to (15) described in FIG. 3, which is a waveform diagram showing the effect of the present invention.

At time t6 in FIG. 6, when a two-phase short circuit accident occurs at point "A" in FIG. An excessive short circuit current containing a direct current component determined by the direction of the internal induced voltage vector at the time of a short circuit flows on the primary side of the wound induction machine 1.
This current is attenuated by the time constant of the primary circuit of the wound induction machine 1, and the waveforms at each part change as shown in (1) to (8).

If the timer 36 detects the time after the occurrence of the short circuit accident and, for example, at time t7 in FIG. 4 after 100 m5ec has passed, the short circuit accident signal 49 in FIG. Then, the U-phase GTO ON signal (10), V-phase GTO ON signal (12), and W-phase GTO signal (14) change to "1" and '0" at predetermined timing, respectively, and the U-phase GT
On/off control is performed on O15, V-phase GTO13, and W-phase GTO17.

<1.1), (13), (1,5) are the respective G
This is the current waveform flowing through TO. Since these operations are the same as those explained in FIG. 3, the explanation will be omitted, but in FIG. 4, the GTO controllable current 53 is set to 50% of that in FIG. 3. In this way, by turning on the control after a certain period of time has elapsed after a short-circuit accident, it is possible to create a zero-crossing point in the primary currents (1) to (3) of the wound induction machine 1 with a small GTO current. The current flowing through the inverter 2 can be reduced. Therefore, the inverter 2 can be made smaller and cheaper.

In the above explanation, the case where GTO is used as the switching element constituting the inverter has been explained, or other switching means such as transistors, other self-extinguishing switching elements, or thyristor circuits with forced commutation circuits are used. The inverter may also be constructed using the following methods.

[Effects of the Invention] As described above, according to the present invention, when a short circuit accident occurs on the primary side of the wound induction machine constituting the Cerbius device,
By passing a relatively small current through the switching elements that constitute the inverter, a direct current component can be superimposed on the secondary current of the wound induction machine. Therefore, since a zero cross point can be created for the fault current flowing to the negative side, a small and inexpensive AC circuit breaker can be used as the negative side circuit breaker. Additionally, by turning on the control that superimposes the DC component after a certain period of time after an accident occurs, the current flowing through the switching elements can be made smaller, which prevents the inverter capacity from increasing to handle the accident current. I can do it. Therefore, it is possible to prevent the inverter from becoming large and expensive. As described above, according to the present invention, a small and inexpensive Cerbius device can be realized, and its economical effects are significant.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a detailed block diagram of the logic circuit of FIG. 11 constituting the present invention, and FIG.
4 is a waveform diagram for explaining the operation of another embodiment of the present invention. FIG. 5 is a waveform diagram for explaining the operation of another embodiment of the present invention.
The figure is a configuration diagram showing a conventional embodiment, and FIG. 6 is an operating waveform diagram according to the conventional embodiment. 1... Wound induction machine, 2... Inverter, 3...
DC power supply, 4... Breaker, 5... Power supply system, 6-1
1...Diode, 12-17...GTo, 18.
...Capacitor, 19~24...Diode, 25~
31...GTO132...Discharge resistor, 33...Transformer, 34...Short circuit accident detector, 35...Current detector, 36...Timer, 37...Logic circuit, 38.G
TO switching signal, 39... polarity inverter, 40~
45...Comparator, 46-48...AND circuit, 49.
...Short circuit fault signal, 50...U phase secondary current, 51...
・V phase secondary current, 52...W phase secondary current, 53...
GTO controllable current, 54... Zero reference, 55... U-phase GTO on signal, 56... V-phase GTO on signal, 57.
・・W phase GTO Onshin agent Patent attorney Takeshi Suzue
Hiko Diagram 2 Procedural Amendment Heisei ℃, Katana 11th

Claims (2)

[Claims] (1) A wound induction machine, an inverter that controls the secondary current of the wound induction machine, a DC power supply that supplies DC voltage to the inverter, a breaker on the primary side of the wound induction machine, and the comprising a short-circuit accident detector on the primary side of a wound induction machine, a current detector that detects the secondary current, and a logic circuit that generates an on/off signal for a switching element of the inverter based on the output of the current detector, When the circuit breaker interrupts a current caused by a short circuit accident occurring on the primary side of the wound wire induction machine, a DC component is superimposed on the secondary current by turning on and off the switching element according to the secondary current value. A control method for a Servius device, characterized in that a zero crossing point is created in the primary current of the wound induction machine. (2) The Serbius device according to claim (1), further comprising a timer for detecting the time after the occurrence of a short circuit accident, and interrupting the current caused by the short circuit accident occurring on the primary side of the wound induction machine with the breaker. At this time, after a certain period of time from the occurrence of a short circuit accident, a DC component is superimposed on the secondary current by turning on and off the switching element of the inverter according to the secondary current value of the wound wire induction machine, and thereby, A control method for a Servius device, characterized in that a zero crossing point is created in the primary current of the wound induction machine.