SU1728989A1 - Method for automatic control of electric-arc furnace - Google Patents

Abstract

The invention relates to electrical engineering. The purpose of the invention is to reduce the specific energy consumption. The regulator 10 generates a controlling effect on the electrode movement in the pulse-width mode according to the switching time specified by timer 9, with the transfer coefficient D. calculated by the formula A-11f AO V1 - V0B, where AO, B o are scale factors, Bi - Power factor . 1 il.

Description

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The invention relates to electrical engineering, in particular, to controlling the electric mode of three-phase arc steel-smelting furnaces.

The purpose of the invention is to reduce the specific energy consumption.

The drawing shows a block diagram of a device implementing a method for automatic control of an electric arc furnace.

The device comprises a meter 1 of the Bi coefficient of the furnace phase power, a block 2 of comparison, a power factor setter 3, a block 4 for calculating the coefficient A of the regulator, a meter 5 for the phase voltage Of, a block 6 for measuring the gradient of the potential in the arc column, a block for calculating the time g of drive electrode, unit 8, the speed of movement of the electrode, the timer 9 and the controller 10 of the movement of the electrode.

The output of the meter 1 of the coefficient BI of the kiln phase power is connected to the first input of the comparator unit 2, the second input of which is connected to the output of the setting unit 3 of the power factor W, the output of which is connected to the first input of the block 4 of calculating the controller's transmission coefficient. The second input of the unit 4 is connected to the output of the meter 5 phase voltage 11f. the output of which is also connected to the first input of the unit 7 for calculating the drive movement time g, the second, third and fourth inputs of the unit 7 are connected respectively to the output of the comparator unit 2, the output of the potential gradient measurement unit 6 at the arc distance arc and the output unit of the electrode speed V displacement 8. The output of the calculating unit 7 is connected to a timer 9. The output of the unit 4 for calculating the expected arc current is connected to the input of the electrode movement regulator 10. The output of block 4, the output of timer 9 and the output of the set points | YU

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Yu

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about

The speed of movement of the electrode drive is 8, the first, second, and third outputs of the device, respectively.

The device works as follows.

Measured by the meter 1, the power factor Bi of the furnace phase is compared in block 2 comparison with the signal setting of the power factor By obtained from the setting unit 3. The deviation value ABi | Bij-B nocTynaeT to the second input of the unit 7. where, taking into account the values of the phase voltage 11f, as well as a potential gradient D in the arc column and a predetermined velocity V of the electrode moving to the first, third and fourth inputs from the outputs of the phase voltage meter 5, respectively. unit 6 for measuring the potential gradient in the arc column and the setting device 8, calculates the time g for moving the drive (not shown) of the electrode using the formula

- $ g-

where Hades is the arc voltage equal to the product D Vg11f.

The measured phase voltage in block 5 is determined as follows:

,, UAB + UBC + UCA Ufz -,

where UAB, UBC, UCA are measured values of linear voltages;

CT - the transformation ratio of the furnace transformer.

In order not to form conflicting commands on the drive of the electrodes, in block 4 the expected, i.e. corresponding to the specified power factor Bi, coefficient A by the formula

AO VI - VOG, (2)

where AO, BO - scale factors;

Bi is the power factor.

The controller 10 generates a controlling effect on the movement of the electrode in a pulse-width mode according to the on-time, calculated from. the formula (1) and set by the timer 9 at the coefficient of transfer of the controller calculated by the formula (2).

Thus, the device allows controlling the movement of the electrodes in accordance with the regimes and changes occurring during the melting process.

parameters of current and voltage of arcs, the elimination of false actuator drive and reducing the load on the equipment from untimely displacement of the electrodes and thereby reduce the specific energy consumption.

Claims (1)

Claims The method of automatic control of an electric arc furnace, at which the transfer coefficient of a regulator is determined and set, the power factor of the furnace phase, the potential gradient in the arc column, the phase voltage and the arc voltage are measured, the voltage of the arc is compared with their mismatch is determined, and the electrode is moved in the direction of decreasing it at a constant speed, due to the fact that, in order to reduce the specific energy consumption, the pulse-width control of the electrode movement, each control period is defined as the ratio of the magnitude of the error between the arc voltage and its specified value to the product of the values of the potential gradient in the arc column and the velocity of the electrode, and the transfer coefficient of the regulator is changed in accordance with with expression A 11f AO Vl- B0Bf, where 11f is a phase voltage; Bi is the power factor; AO, In - scale factors. VT 4i