JP3092284B2 - Electric current control device for arc furnace electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current control device for an arc furnace electrode for controlling an arc of the electrode using a saturable reactor or the like, and more particularly to a current control for an arc furnace electrode capable of performing any overload operation. Related to the device .

[0002]

2. Description of the Related Art Conventionally, a device shown in FIG. 2 is known as a current control device for an arc furnace electrode for controlling an arc of an arc furnace. In FIG. 2, reference numeral 10 denotes a current setting device,
The set value of the current setter 10 is input to the adder 20 when the switch 12 is closed by an operation command. Adder 1
6, the deviation between the actual current value Iist and the set value of the limiting current setting unit 14 is further input to the adder 20 via the low limiter 18, and the current setting unit 1
The deviation from the set value of 0 is taken. The difference between the deviation value output from the adder 20 and the actual current value Iist is again taken by the adder 22, and this difference value is passed through the current controller 24 operating PI (proportional / integral) to obtain a saturable reactor 26. To control the current of an arc furnace electrode (not shown) by the actual current value Iist which is the output of the saturable reactor. That is, the conventional current control device for an arc furnace electrode subtracts only the current actual value Iist exceeding the current limit value set by the limit current setter 14 from the set current value of the current setter 10, and as a result Is the set current value of the current controller 24, and a device for controlling the actual current value Iist to be equal to or less than the current limit value.
It is a place.

[0003]

However, according to the above-described current control device for an arc furnace electrode, if the actual current value exceeds the limit value due to a failure of the current regulator, the actual current value is reduced to the limit value. There was a problem that it could not be suppressed within. Also, in the above-described conventional device , since the actual current value exceeds the current limit value by subtracting from the set current value of the current setting device, the set current value changes in a step-like manner, and the arc of the electrode may be cut off. There was sex.

Accordingly, an object of the present invention is to provide an arc furnace in which the current is limited even when the current regulator is out of order, the current is gently limited without turning off the arc of the electrode, and any overload operation can be performed. An object of the present invention is to provide an electrode current control device .

[0005]

A current control device for an arc furnace electrode according to the present invention applies an output of a current controller operating in proportion to an integral to a saturable reactor, and obtains an output based on a current actual value which is an output of the saturable reactor. In a current control device for controlling an arc of an arc furnace electrode, an upper limit current limiter connected between an output side of the current regulator and a saturable reactor, a limit current value and a current set by a limit current setting unit. Enter the deviation from the actual value to perform proportional integration.
And a PI controller for performing the control , wherein the output of the PI controller is input to the upper limit current limiting means, whereby the upper limit current applied to the saturable reactor is controlled.

[0006]

According to the arc furnace electrode current control device of the present invention, the upper limit current limiting means connected between the output side of the current regulator and the saturable reactor, and the limit set by the limit current setting means are provided. a PI controller that performs enter proportional integral operation of a deviation between the current value and the current actual value is provided, wherein
The upper limit current applied to the saturable reactor is controlled by inputting the output of the PI controller to the upper limit current limiting means. Thus, even when the current regulator is out of order, the current can be gently limited without turning off the arc of the electrode.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a current control device for an arc furnace electrode according to the present invention.
Per Example of location will be described in detail with reference to the accompanying drawings.

[0008] Figure 1 is a block diagram of a control circuit showing an embodiment of a current control device for arc furnace electrodes according to the present invention. The same components as the components shown in the conventional example of FIG. 2 will be described with the same reference numerals. In FIG. 1, an adder 20 is a current setting device 10 via a switch 12.
And the current actual value Iist, and the deviation is input to a current controller 24 which performs a proportional / integral operation.
On the other hand, the adder 16 calculates a deviation between the set value of the limited current setting device 14 which can be arbitrarily set and the actual current value Iist, and uses the deviation value as a P which performs a proportional / integral operation with a high limiter function.
Input to the I adjuster 30. The output of the current regulator 24 is applied to the saturable reactor 26 via the high limiter 28, and controls the current of the arc furnace electrode (not shown) by the actual current value Iist which is the output of the saturable reactor. Also,
The upper limit of the high limiter 28 is configured to be adjusted by the PI adjuster 30.

[0009] The operation of the current control device for the arc furnace electrode of the control circuit thus configured is as follows. First,
When the operation command is off, the switch 12 is open and the PI
The output of the controller 30 is the result of matching the set value of the limiting current setter 14 with the actual current value Iist, that is, since the actual current value Iist is zero, the set value of the limited current setter 14 is input and saturated. I have. Therefore, the PI controller 30 determines that P
The upper limit determined by the limiter of the I adjuster 30 itself is actually output, and this output is the upper limit of the high limiter 28.

When the operation command is turned on to enter the operation state, the switch 12 is closed and the set value of the current setter 10 is input to the adder 20. When the arc furnace is in operation, the current regulator 24 is normal and the adder 20
If the line of the other actual current value Iist which is input to is not broken and is equal to or less than the current value set by the limiting current setting device 14, the high limiter 28 is operated without changing the upper limit value.

Here, if the current regulator 24 malfunctions, the line of the actual current value Iist input to the adder 20 is broken, or the current actual value Iist is changed by the limiting current setting device 14 due to other factors. Even if the set current value is exceeded, the adder 16 takes a deviation between the set value of the current limiter 14 and the actual current value Iist.
The limit current setting unit 14 which is set to be lower than the limiter upper limit value of the PI controller 30 itself because it is input to the controller 30.
The current is gently limited by the PI controller 30 up to the set value.

Further, in the configuration of FIG. 1, the current limiter set by the current limiter 14 is set to 100%.
0 is set to a value exceeding 100%, and P
If the limiter upper limit value of the I adjuster 30 itself is set to 100% or more, the electrode adjuster 30 can perform an arbitrary overload operation of the electrode.

[0013] Incidentally, P I controller 30, depending on the circuit constants, it is needless to say that allows equivalent thing in I regulator only integration operation.

[0014]

As is apparent from the above-described embodiments, according to the present invention, the upper limit current limiting means connected between the output side of the current regulator and the saturable reactor and the limit current setting means set the upper limit current limiting means. And a PI controller for performing a proportional integral operation by inputting a deviation between the limited current value and the actual current value . An output of the PI controller is input to the upper limit current limiting means, and thereby a saturable reactor is provided. By controlling the upper limit current applied to the electrode, the current can be gently limited without turning off the arc of the electrode even when the current regulator is malfunctioning. You can also drive.

The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various design changes can be made without departing from the spirit of the present invention. It is.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control circuit showing an embodiment of a current control device for an arc furnace electrode according to the present invention.

FIG. 2 is a control diagram showing a conventional arc furnace electrode current control device.
It is a block diagram of a circuit .

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Current setter 12 Switch 14 Limiting current setter 16 Adder 18 Low limiter 20 Adder 22 Adder 24 Current adjuster 26 Saturable reactor 28 High limiter 30 PI adjuster

Claims (1)

(57) [Claims] 1. A current controller for applying an output of a current controller that performs a proportional-integral operation to a saturable reactor and controlling an arc of an arc furnace electrode by an actual current value which is an output of the saturable reactor. The upper limit current limiting means connected between the output side of the power supply and the saturable reactor, and the deviation between the limit current value set by the limit current setting means and the actual current value are input to perform a proportional integral operation.
A current control device comprising: a PI adjuster ; and inputting an output of the PI adjuster to the upper limit current limiting means to control an upper limit current applied to the saturable reactor.