JPH1078825A - Power source device for electrolytic plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the starting time of a power source device for an electrolytic plant. SOLUTION: This device is composed of a breaker 1, load time tap switching transformer 2, transformer 3 for a rectifier, voltage control reactor 4, diode rectifier 5, and control circuit 20 or the like. At the time of starting, a dead zone time to an anode effect is by-passed by a tap switching control circuit 23 of the control circuit 20. Then, the tap of the load time tap switching transformer 2 is increased one by one until the detected value of a current detector 6 is made almost equal to the set value of an output power setting equipment 11 by operating a motor 2a of a load time tap switcher provided at the load time tap switching transformer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a main circuit which is used in an aluminum electrolytic plant or the like and is connected in series with a load tap switching transformer, a rectifier transformer, a voltage control reactor, and a diode rectifier. The present invention relates to a power supply device for an electrolytic plant including a control circuit for controlling a circuit.

[0002]

2. Description of the Related Art FIG. 3 shows a configuration diagram of a power supply device for a conventional electrolytic plant of this kind. In FIG. 3, 1 is a circuit breaker, 2
Is a load tap change transformer, 3 is a rectifier transformer, 4 is a plurality of voltage control reactors (hereinafter, also simply referred to as VCRs), 5 is a diode rectifier comprising a plurality of diodes, and 6 is an output of the diode rectifier 5. A current detector for detecting a current; 7 a thyristor for supplying a desired value of current from an auxiliary power supply (not shown) to each control winding of the VCR 4; 8 a shunt resistor for detecting a current of the control winding;
Reference numeral 10 denotes a control circuit.

Here, when the current of each control winding of the VCR 4 is increased, the impedance of the VCR 4 increases with the increase of the current, and the input voltage of the diode rectifier 5 decreases. It is assumed that the output current decreases. The control circuit 10 also includes an output current setting device 11 for setting the output current of the diode rectifier 5.
A current adjuster 12 that performs an adjustment operation based on a deviation between a set value of the output current setter 11 and a detected value of the current detector 6;
A firing angle adjuster 13 for adjusting a firing phase of a thyristor 7 for supplying a current to each control winding of the VCR 4 based on an output value of the current controller 12, and the control winding detected via a shunt resistor 8. A VCR current upper limit detector 14 that outputs a signal when a current flowing through the VCR exceeds a predetermined upper limit value;
Similarly, a VCR current lower limit detector 15 that outputs a signal when the current flowing through the control winding detected via the shunt resistor 8 falls below a predetermined lower limit, an output of the VCR current upper limit detector 14 and a VCR A tap switching control circuit 16 for operating the motor 2a of the on-load tap changer included in the on-load tap change transformer 2 based on the output of the current lower limit detector 15.

[0004] The operation of the control circuit 10 shown in FIG. 3 will be described below with reference to the flowchart shown in FIG. 4 focusing on the control operation of the tap switching control circuit 16. In a state where the circuit breaker 1 is turned on and the output current of the diode rectifier 5 is controlled by the current regulator 12, the firing angle regulator 13, and the thyristor 7 based on the set value of the output current setter 11 (step S40). The tap switching control circuit 16 first determines whether or not the VCR current lower limit detector 15 outputs the signal (step S41). If the signal has been output (step S41, branch Y), the VCR 4 In order to increase the current of each of the control windings, a tap-up command is output to the motor 2a of the on-load tap changer of the on-load tap change transformer 2 (step S42), and the on-load tap change transformer 2 has one tap. Wait until the time required to ascend (for example, about 3 seconds) elapses (step S4
3) Further, assuming that an anode effect has occurred at an electrode connected to the output of the diode rectifier 5, a dead zone time (for example, about 15 seconds) for which the load tap switch does not operate during the occurrence of the anode effect. (Step S44), and the process returns to step S41.

If the VCR current lower limit detector 15 does not output the signal at step S41 (branch N), it is determined whether the VCR current upper limit detector 14 outputs the signal (step S45). ), If the signal has been output (step S45, branch Y), a tap-down command is output to the motor 2a of the on-load tap changer to reduce the current of each control winding of the VCR 4 (step S46). ), And waits for the time (for example, about 3 seconds) required for the on-load tap switching transformer 2 to drop by one tap (step S47), and proceeds to step 44 described above, and thereafter returns to step S41.

Further, when the VCR current upper limit detector 14 does not output the signal at the step S45 (branch N), the current of the respective control windings of the VCR 4 is within the normal control range, so that the process returns to the step S41. .

[0007]

According to the conventional power supply device for an electrolysis plant, immediately after the electrolysis plant is started and the circuit breaker 1 is turned on, the on-load tap switching of the transformer 2 is performed. The current in the control winding of the VCR 4 is increased by the current regulator 12, the firing angle regulator 13 and the thyristor 7 to increase the output current of the diode rectifier 5. Since the VCR current lower limit detector 15 is in the state of outputting the above signal, the on-load tap changer of the on-load tap change transformer 2 sequentially taps one tap at a time from the tap position, for example, about 100 taps in total. The output current of the diode rectifier 5 is increased so as to reach the set value of the output current setter 11 by increasing the output current.

At this time, the tap switching control circuit 16 performs the above-described steps S41 → S42 → S43 →
The operation of step S44 → step S41 is performed,
It takes, for example, about 30 minutes for the output current of the diode rectifier 5 to reach the set value of the output current setting unit 11, and this time is a value that cannot be ignored in the electrolytic plant.

An object of the present invention is to provide a power supply device for an electrolytic plant that solves the above problems.

[0010]

SUMMARY OF THE INVENTION The present invention provides a main circuit comprising a series connection of a load tap switching transformer, a rectifier transformer, a voltage control reactor, and a diode rectifier, and a control circuit for controlling the main circuit. In the power supply device for an electrolytic plant, comprising: an output current setter for setting the output current of the main circuit, a set value of the output current setter, and a detected value of the output current of the main circuit. A current controller that performs an adjustment operation based on a deviation from, and a firing angle controller that adjusts a firing phase of a thyristor that causes a current to flow through a control winding of the voltage control reactor based on an output value of the current controller.
A current upper limit detector that outputs a signal when a current flowing through the control winding via the thyristor exceeds a predetermined upper limit, and a current flowing through the control winding via the thyristor has a predetermined lower limit. A current lower limit detector that outputs a signal when the output voltage falls below a lower limit, a ratio setter that outputs a value obtained by reducing a set value of the output current setter by a predetermined ratio, an output value of the ratio setter, and the main circuit. And a comparator that outputs a signal when the detected value exceeds the output value, an output of the current upper limit detector, an output of the current lower limit detector, and a comparator. A tap switching control circuit for operating the on-load tap changer of the on-load tap change transformer based on the output.

According to the present invention, there is provided a tap switching control circuit that operates based on the output of the current upper limit detector, the output of the current lower limit detector, and the output of the comparator.
As will be described later, at the time of starting this electrolytic plant, the dead zone time based on the above-described anode effect is bypassed,
The time required for the output current of the main circuit to reach the set value of the output current setting device can be shortened.

[0012]

FIG. 1 is a block diagram of a power supply device for an electrolysis plant according to an embodiment of the present invention. The same power supply device as the conventional power supply device for an electrolysis plant shown in FIG. The reference numerals are attached and the description is omitted. That is, in FIG. 1, the control circuit 20 includes an output voltage setting device 11,
In addition to the current adjuster 12, the firing angle adjuster 13, the VCR upper limit detector 14, and the VCR lower limit detector 15, a ratio setter 21
, A comparator 22, and a tap switching control circuit 23.

Here, the ratio setter 21 is an output current setter 1
The comparator 22 compares the output value of the ratio setter 21 with the detection value of the current detector 6 and outputs a value that is smaller than the output value. Output a signal when That is, when the set value of the output current setter 11 and the detection value of the current detector 6 are substantially equal, the ratio of the ratio setter 21 is set so that the comparator 22 reliably outputs the signal.

The operation of the control circuit 20 shown in FIG. 1 will be described below with reference to the flowchart shown in FIG. 2 focusing on the control operation of the tap switching control circuit 23. The electrolysis plant is started, the circuit breaker 1 is turned on, and the output current of the diode rectifier 5 is controlled by the current controller 12, the firing angle adjuster 13, and the thyristor 7 based on the set value of the output current setter 11. In the state after the operation (Step S20),
The tap switching control circuit 23 first determines whether or not the VCR current lower limit detector 15 outputs the signal (step S21). If the signal is output (step S2)
1, branch Y), a tap-up command is output to the motor 2a of the on-load tap changer of the on-load tap change transformer 2 to increase the current of each control winding of the VCR 4 (step S22). After the time required for the switching transformer 2 to rise by one tap (for example, about 3 seconds) elapses (step S23), it is determined whether or not the comparator 22 outputs the signal (step S24). When the signal is not output (step S24, branch N), the process returns to step S21.

When the comparator 22 outputs the signal in step S24 (branch Y), the state where the set value of the output current setting unit 11 and the detection value of the current detector 6 are substantially equal, that is, the start is completed. Or, since it is in a normal control state, it is further assumed that an anode effect has occurred at an electrode connected to the output of the diode rectifier 5, and a dead zone time period during which the on-load tap changer does not operate during the occurrence of the anode effect. After waiting for (for example, about 15 seconds) (step S25), the process returns to step S21.

If the VCR current lower limit detector 15 does not output the signal in step S21 (branch N), it is determined whether the VCR current upper limit detector 14 outputs the signal (step S26). If the signal has been output (step S26, branch Y), a tap-down command is output to the motor 2a of the on-load tap changer in order to reduce the current of each control winding of the VCR 4 (step S27). ), And waits for the time (for example, about 3 seconds) required for the on-load tap switching transformer 2 to drop by one tap (step S28), and proceeds to step 25 described above, and thereafter returns to step S21.

Further, when the VCR current upper limit detector 14 does not output the signal at the step S26 (branch N), the current of each control winding of the VCR 4 is within the normal control range, so that the process returns to the step S21. . According to the power supply device for an electrolysis plant of the present invention, immediately after the electrolysis plant is started and the circuit breaker 1 is turned on, the on-load tap changer of the on-load tap change transformer 2 is at the tap position at the start. In the state of the lowest tap, the VCR 4 is controlled by the current controller 12, the firing angle controller 13, and the thyristor 7.
Since the VCR current lower limit detector 15 is in the state of outputting the signal in order to increase the output current of the diode rectifier 5, the on-load tap switching of the transformer 2 The output current of the diode rectifier 5 is increased by tapping the tap position one by one from the tap position, for example, about 100 taps in total, so as to reach the set value of the output current setter 11.

At this time, in the tap switching control circuit 23, the aforementioned step S21 → step S22 → step S23 →
The operation of step S24 → step S21 is performed, for example, about 96 times based on the ratio of the ratio setting unit 21, and thereafter, the operation of step S21 → step S22 → step S23 → step S24 → step S25 → step S21 is performed. It takes only about 6 minutes for the output current of the diode rectifier 5 to reach the set value of the output current setter 11, for example.

[0019]

According to the present invention, by providing a tap switching control circuit that operates based on the output of the VCR current upper limit detector, the output of the VCR current lower limit detector, and the output of the comparator, the electrolytic plant can be provided. At start-up, the dead zone time based on the anode effect described above is bypassed, so that the time required for the output current of the diode rectifier to reach the set value of the output current setting device can be reduced to about 1/5 of the conventional case, and the operating rate can be reduced. Improvement can be measured.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a power supply device for an electrolytic plant showing an embodiment of the present invention.

FIG. 2 is a flowchart illustrating the operation of FIG. 1;

FIG. 3 is a configuration diagram of a power supply device for an electrolysis plant showing a conventional example.

FIG. 4 is a flowchart for explaining the operation of FIG. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Breaker, 2 ... Tap change transformer at load, 3 ... Transformer for rectifier, 4 ... Voltage control reactor, 5 ... Diode rectifier, 6 ... Current detector, 7 ... Thyristor, 8 ... Shunt resistance, 10 ... Control Circuit, 11 ... Output voltage setting device, 12 ...
Current regulator, 13: firing angle adjuster, 14: VCR upper limit detector, 15: VCR lower limit detector, 16: tap switching control circuit, 20: control circuit, 21: ratio setting device, 22: comparator, 23 ... Tap switching control circuit.

Claims (1)

[Claims] 1. An electrolysis plant comprising: a main circuit comprising a series connection of a load tap switching transformer, a rectifier transformer, a voltage control reactor, and a diode rectifier; and a control circuit for controlling the main circuit. In the power supply device, the control circuit may further include: an output current setting device that sets an output current of the main circuit; and an adjustment operation based on a deviation between a set value of the output current setting device and a detection value of an output current of the main circuit. A current adjuster that adjusts a firing phase of a thyristor that supplies a current to a control winding of the voltage control reactor based on an output value of the current adjuster; and the control winding via the thyristor. A current upper limit detector that outputs a signal when a current flowing through the line exceeds a predetermined upper limit; and a signal that outputs a signal when the current flowing through the control winding via the thyristor falls below a predetermined lower limit. Current lower limit detector to be applied; a ratio setter that outputs a value obtained by reducing a set value of the output current setter by a predetermined ratio; an output value of the ratio setter and a detected value of an output current of the main circuit. And a comparator that outputs a signal when the detected value exceeds the output value, based on an output of the current upper limit detector, an output of the current lower limit detector, and an output of the comparator. And a tap switching control circuit for operating the on-load tap changer of the on-load tap change transformer.