JPS6116758Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a power failure protection device that prevents the destruction of the thyristor element in a thyristor conversion device during a power outage, or prevents the fuse for protecting the thyristor element from blowing out. In particular, the present invention relates to protection of thyristor elements and fuse blowout prevention device against main circuit power outage or phase shifter power outage during inverter operation in an anti-parallel connection type reversible thyristor Leonard device.

(Prior Art) In a thyristor Leonard device that performs inverter operation, if the main circuit power supply fails during inverter operation, a DC short circuit occurs, and if the phase shifter power supply fails, commutation failure occurs due to loss of gate pulses. In either case, there is a risk that the thyristor element will be destroyed, and the fuse for protecting the thyristor element will be blown out and must be replaced.

For this reason, in the past, an induction motor or a capacitor charging circuit was connected in parallel to the phase shifter power supply, and even if the main circuit power supply failed, the phase shifter would continue to operate for a while due to the residual voltage of the induction motor or the discharge voltage of the capacitor. The power supply is ensured so that the gate pulse does not disappear until the high-speed circuit breaker in the main circuit is completely opened.

FIG. 1 is a block diagram of a circuit showing a conventional example using an induction motor, in which 100 is a power failure protection device, 101 is a thyristor switch, 102 is a low voltage relay, 103 is an induction motor, 104 is a thyristor converter control unit, 105 is a thyristor Leonard main circuit section, 106 is a high speed circuit breaker, 107
is a DC motor, 108 is a DC reactor, 109
are thyristors and are connected in series with protective fuses (not shown). 110 is a three-phase main circuit power supply.

During a power outage, the low voltage relay 102 detects a drop in the main circuit power supply voltage and opens the high-speed circuit breaker 106, and also opens the thyristor switch 101 to open the phase shifter (not shown) in the thyristor converter control unit 104. 1) Switch the power source from the main circuit power source 110 to the residual induced voltage generated by the induction motor 103. Further, a gate block signal is given from the low voltage relay 102 to the thyristor converter control unit 104, and the gate pulse is generated at a control delay angle α° (=approximately
150°).

(Problem that the invention aims to solve) However, in such a conventional example, the reference phase disappears when the power supply is switched by the induction motor or the capacitor, so the thyristor control phase by the gate block signal after switching is changed to the main circuit. The phase may not match the phase before the power outage, and commutation may not occur smoothly, potentially damaging the thyristor element. In addition, those using a rotating machine have drawbacks such as vibration and noise. .

(Means for solving the problem) The present invention is designed to eliminate the above-mentioned drawbacks, and uses a capacitor as the power source for the transfer device during a power outage. A gate block signal synchronized with the thyristor control phase is generated by a circuit equipped with a sawtooth wave type trigger pulse generator and a ring counter using one phase of the device power supply as a reference, and this gate block signal is synchronized with the thyristor control phase when switching the power supply. The phases of the gate pulses are matched by a block signal.

(Embodiment) FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention. The same reference numerals as in FIG. 1 indicate the same parts. 200 is a power failure protection device of the present invention, 201 is a thyristor converter control unit, 20
2 is a low-voltage relay, 203 is a low-pass filter to prevent malfunction in the commutation overlap section, and 204 is a trigger for control delay angle α° (= about 150°) by delay signal F from low-pass filter 203. Pulse generator, 205 monostable multivibrator, 20
6 is a clock pulse generator, 207 is a ring counter, 208 is a diode, and 209 is a capacitor.

In a steady state, a phase shifter power supply E, which is converted into six phases in this embodiment according to the number of thyristor elements, is created in the thyristor converter control unit 201 by power supply from the main circuit power supply 110, and among these, A signal D synchronized with this voltage, for example, R-S, is applied to a low-pass filter 203, and a delayed signal F, whose phase is delayed, is input to a trigger pulse generator 204. Trigger pulse generator 20
4 is a means as disclosed in Patent Application Publication No. 21187 of 1971, when a sawtooth trapezoidal wave SW is generated in the negative section of this delayed signal F, and the reference bias voltage V _B etc. , control delay angle α゜(=
A pulse signal KP of approximately 150°) is sent out. With this pulse signal KP, the monostable multivibrator 205
Trigger the monostable multivibrator 205
For example, for one cycle depending on the power supply frequency,
At 50Hz, the inhibit signal is approximately 20ms wide.
Send IN. While this inhibit signal IN is being sent, the clock pulse generator 206 generates six clock pulses corresponding to the number of thyristor elements.
CL is sent. This clock pulse CL enters a six-stage ring counter 207, which generates gate block signals CB1 to CB6 for each clock pulse.

However, in steady state, low voltage relay 202
Since the clear (or reset) signal K is always sent from the ring counter 207, the gate block signal GB is not sent from the ring counter 207.

For example, if the main circuit power supply voltage or the phase shifter power supply voltage drops at time t due to a power outage or the like, the low voltage relay 202 detects the voltage drop and cuts off the signal entering the phase shifter within the thyristor converter control unit 201. In addition to sending out the signal T, the signal HS which opens the high-speed circuit breaker 106 and the signal H which holds the output of the monostable multivibrator 205 are sent out, and the clear signal K disappears. Further, instead of the main circuit power supply, the discharge voltage S of the capacitor 209 stored through the diode 208 in a steady state is discharged as a power supply for each part.

Therefore, the phase shifter is powered by the phase shifter power supply E by the signal T.
The steady gate pulse that had been generated at a phase corresponding to
The gate pulse GP is sent out in accordance with the gate block signal GB sent from the capacitor 209, and the gate pulse GP is continued until the charge stored in the capacitor 209 finishes discharging. During this time, the high speed circuit breaker 106 is completely opened. be done.

(Effects of the present invention) As described above, in the present invention, the gate block signal from the ring counter is generated based on one phase of the power supply voltage even in a steady state, and the phase shift occurs due to a voltage drop such as a power outage. The gate pulse after the device power source is switched from the main circuit power source to the discharge voltage stored in the capacitor is generated by the gate block signal, and its phase can be completely matched with the previous phase, and the thyristor In addition to safely reducing the current and providing reliable protection, ring counters and monostable multivibrators are also equipped with C2MOS (Clocked Complementary
Metal Oxide Semiconductor), it consumes less power, and even if the capacitor capacity is small, the device can operate stably until the high-speed circuit breaker is completely opened, and the device can be made smaller. be.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional circuit, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a time chart of input and output signals of various parts of the circuit shown in FIG. 100... Conventional power failure protection device, 101... Thyristor switch, 102... Low voltage relay, 1
03...Induction motor, 104...Thyristor conversion device control section, 105...Thyristor Leonard main circuit section, 106...High speed circuit breaker, 107...DC motor, 108...DC reactor, 109...
...Thyristor, 110...Three-phase main circuit power supply, 20
0... Power outage protection device of the present invention, 201... Thyristor converter control unit, 202... Low voltage relay,
203... Low pass filter, 204... Trigger pulse generator, 205... Monostable multivibrator, 206... Clock pulse generator, 207
...Ring counter, 208 ...Diode, 2
09...Capacitor.

Claims (1)

[Scope of utility model registration request] In a thyristor conversion device that maintains a gate pulse by supplying a discharge voltage when the power supply voltage drops using a capacitor charged in a steady state,
a trigger pulse generator that sends out a trigger pulse according to the phase of the phase shifter power supply voltage in a steady state; a monostable multivibrator that receives the trigger pulse and sends out an inhibit signal that is maintained even when the power supply voltage drops; A clock pulse generator that sends out a predetermined number of clock pulses while a signal is being sent, a gate block signal that generates gate pulses sequentially for each of the clock pulses, and this gate block signal that is sent out when the power supply voltage drops. A power outage protection device featuring a ring counter.