SU1534277A2 - Arrangement for controlling the electric duty of steel-melting electric-arc furnace - Google Patents

Abstract

The invention relates to electrical engineering. The purpose of the invention is to improve the quality of regulation by optimizing the melting conditions. By maintaining the contour transfer coefficient at a predetermined level, the control parameters of the control system are stabilized, and the electrical control program is corrected. This reduces power consumption. 1 il.

Description

The invention relates to electrothermal, can be used to control the electric mode of an electric arc furnace and is an improvement of the device according to the author. St. No. 1247640.

The aim of the invention is to improve the quality of regulation by optimizing melting modes when using the correction of a given electric mode control program as a function of changing the transmission coefficient K of an electric furnace and stabilizing the quality of power regulation by maintaining the transfer ratio of the closed-loop control system at a given level.

The drawing shows a block diagram of the device.

A device for controlling the electric mode of an electric arc furnace has in its circuit

control of each phase sensor 1 current arc and sensor 2 arc voltage, block 3 setting thresholds, analyzer

4 electric mode, two keys

5 and 6, power controller 7, thyristor block 8, actuator

9i common to all phases shaper

10blocks, block 11 of setting the dead zone and block 12 of the current of arc power, the first output of current sensor 1 of each phase is connected to the first input of the corresponding electric mode analyzer 4, the second output of current sensor 1 is connected to the first input of block 3 of setting thresholds of the same phase, and the third output of current sensor 1 is connected

with v formation input of the first key 5, the first output of the power current setting unit 12 is connected to the second inputs of the threshold setting units 3, the second output of the current setting unit 12

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power is connected to the information inputs of the second keys 6 of the control circuit of each phase, and the third output of the current setting (power) unit 12 is connected to the input of the switch of 13 voltage levels of the furnace transformer, the output of the dead zone setting unit 11 is connected to the third inputs of the 3 sets of thresholds four outputs Each block 3 of the thresholds is connected to four inputs (second, third, fourth and fifth) of the 4 electrical modes analyzer corresponding to this phase, and the sixth input of the last is connected to the sensor output voltage arc of the same phase, four outputs of each analyzer 4 electric mode connected to the corresponding of the twelve inputs of the driver 10 prohibitions, the first output of the latter is connected to the control input of the first key 5 of the control circuit. and A, and the second output with control output - the key 6 of the control circuit of phase A, the outputs of these keys are connected to the first and second inputs of the regulator 7 of the Power (current) of phase A, the output of the latter is connected to the input of the thyristor unit 8, and the output of the thyristor unit 8 is connected to the input Phase A electrode mechanism 9, the third and fourth outputs of the driver 10 prohibitions are connected in the same way with similar blocks of the control circuit of phase B, and the fifth and sixth outputs of the driver 10 of the prohibitions are connected in the same way with those of the phase C control circuit.

In addition, three adders 14 - 16, an object modeling block 17, four multipliers 18-21, an integration and memory block 22, a program correction block 23 are inputted into the device, and three inputs of the first additional adder 14 are connected to the third outputs of three current sensors 1 phases, three inputs of the second additional adder 15 are connected to the first additional outputs of the power regulators 7 sin phases, and the output of the second additional adder 15 is connected to the input of the modeling block 17, the output of which is connected to the first input of the third about additional adder 16, the second input of the latter is connected to the first output of the first additional adder 14, the output of the third dopol

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The adder 16 is connected to the first input of the first multiplication unit 18, the second input of the last is connected to the second output of the first additional adder 14, and the output of the first multiplication unit 18 is connected to the input of the integration and storage unit 22, the first three outputs of which are connected to the first inputs of the second 19, the third 20 and fourth 21 multiplication units (phase adjustment systems A, B, C), the second inputs of which are connected to the second additional outputs) of the controllers 7 of the power of the three phases A, B, C, and the outputs of the second, third and fourth blocks multiply cocks 19-21 are connected to the additional inputs of the respective power regulators 7 of the three phases A, B, C, the fourth output of the integration and storage unit 22 is connected to the input of the correction unit 23, and the output of the last is connected to the first input of the current reference unit 12 a) arc, to the second input of which a preliminary task of the melting program is supplied, specific electric power consumption, actual electric power consumption, lining temperature, etc., information is needed (not shown), the third additional output of block 12 is set current (power) is connected to the input of the switch 13 steps the voltage for the transformer of the furnace.

The power regulator 7 comprises a serially connected adder 24, a power regulator unit 25 directly, an executive motor speed controller 26, an executive motor current regulator 27, the output of which is the output of the power regulator 7, the first and second inputs of the adder 24 are connected to the outputs respectively, the first 5 and second 6 keys are the inputs of the power regulator 7, the output of the adder 25 is connected to the first input of the speed regulators 26, the second and third outputs of the adder 24 of each phase are connected respectively with the second inputs of the second, third and fourth blocks 19-21 of multiplying each phase and the inputs of the second additional adder 1 5 and are the first and second additional outputs of power regulator 7, the second input of regulator 26 of the speed of the executive motor of each fata is connected by g outputs the second, third and fourth stocks of 19-21 VM-, respectively. and nlle.s with an additional input of power regulator 7.

The device works as follows.

From the sensor of the current of the arc of the phase, the signal from the second output goes to the first input of the block 3 setting thresholds for this phase, the second inputs of the blocks 3 setting the thresholds of each phase (A, B, C) receive signals from the first output of block 12 setting the current (power) and on the third inputs - the signal from the output of block 11 of the deadband setting. At the four outputs of each block 3, the tasks of the thresholds are formed by signals proportional to: at the first output - the minimum arc current of the phase I "MW; at the second output - the lower threshold of the IMI deadband at the third output - the upper threshold

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the prohibition on the movement of the voltage during the closure (short circuit) f of the fatah and the activation on the double side of these electrodes upwards in the absence of current in the third phase, where there is permission; the prohibition of downward movement in a short-circuit in a given phase and the permission to move the electrode upward of the same phase, as well as in the presence of current and voltage in other phases - a ban on movement in these seals and down and up by time At, after this time the electrodes rise up under the action of a current signal; prohibition of downward movement in the same phase where there is a short-circuit, and prohibition of movement in the same phase where there is current, and permission to move in the third phase, where there is no current; if current is broken in one of the phases and current is present in other phases, prohibition of the movement of the electrodes in those phases where there is a current and permission to move the electrodes of the phases in which there is no current; with short circuit in

dead band I

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on the 25 th three phases ban on the movement down

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Vertical output - the maximum allowable arc current phase 1 lax.

These four signals of each phase unit 3 of setting the thresholds arrive at the second, third, fourth and fifth inputs of the corresponding phase analyzer 4 electrical mode, the first input of which receives the signal g of the first output of the arc current sensor 1 of the same phase, and the sixth input - signal from the output of sensor 2, the arc voltage of the same phase.

In the electric mode analyzer 4, the magnitude of the current and voltage of the arc is compared with the predetermined thresholds-Q and the logical signals are generated at the output: the first output is a short circuit (I e I msss); second exit - touch the charge (e op) I third vy35

and permission to move up all three electrodes; in the presence of voltage on the electrodes and the absence of that, in all three phases all the electrodes are absorbed; in case of equality of the current of the arc current of the task, a ban is applied on the opening of the electrode with the deadband enabled.

The signal from the first output (prohibition of the movement of the F-ZA A electrode) of the generator 10 prohibitions goes to the control input of the first key 5 of the phase A, the information input of which receives the signal from the third output of the sensor of the current of the arc of phase A.

From the second input of the driver, a signal is sent (the prohibition of the movement of a phase A electrode down) to the control input of the second key 6 of phase A, the information input of which receives a signal from the second output of the current (power) setting unit 12 gi.

stroke - the arc current is in the dead zone (1H (1 d IH) quarter-th output - arc break (I 5.

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The signals from the outputs of the analyzers 4 electrical mode (all three phases are fed to twelve inputs of the generator 10 prohibitions, which performs the following functions: stopping the electrode when it touches the charge (in the absence of current and voltage decreases below a predetermined threshold), i.e. occurs by relieving the voltage of the task, under the action of which this electrode is lowered;

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and permission to move up all three electrodes; in the presence of voltage on the electrodes and the absence of current in all three phases, all electrodes are lowered; in case of equality of the current of the arc to the current of the task, a ban is applied on the NFR of the electrode with the deadband enabled.

The signal from the first output (the prohibition of the movement of the F-ZA electrode upwards) of the driver 10 of the prohibitions goes to the control input of the first key 5 of phase A, the information input of which receives a signal from the third output of the sensor of the current of the arc of the phase A.

From the second input of the inhibitor, a signal is received (the prohibition of the movement of the electrode of the A phase down) to the control input of the second key 6 of the phase A, the information input of which receives a signal from the second output of the current (power) setting unit 12 g - g.

If there is a control signal at the input of the first switch 5, the latter is closed and the signal from the arc current sensor is not fed to the input of the regulator 7 of the power of phase A, i.e. no current feedback. If there is no prohibitive signal at the control input of the second luch 6, then the signal from the arc current (power) setting unit 12 is fed to the input of the Phase A power regulator 7,

follow the pattern. A signal is formed - a command to move the lex of a kind down. This ng ar enters the input of the thyristors block 8, is amplified and feeds an actuator E to the input, which moves the phase A electrode.

If there is a inhibit signal at the control input of the second switch 6 and there is no one at the control input of the first switch 5 to the input of the power regulator 7, a current feedback signal passes (from the arc current sensor 1) and does not pass a signal from the task unit 12 power current) arcs In this case (in the absence of a task and in the presence of a gok arc), the regulator of the 7th power sees a signal for movement

“Of the end of the arc until the arc of the arc disappears or the prohibition signal is removed from the control, which is the input of the second key 6 of the circuit of the phase L.

From the third and fourth exit of the imaging unit 10, the prohibition of the signals is received at the control inputs of the corresponding- ((- of course, the first i jroporo keys (S and M peni fa n, i B.

С r i ο о о and those (that is the output of the form of the thermotech (P 3 t sig from you t to v4ip innqtoinn inputs are coherent. The signal of the poker circuit (S and 6) of the phase G chain

On the hirs h about / irpBoro kchyuch 5 tse pi ftzp R gk (iyna i sigal with dchtchi- i i I 11 to i, g and fa 311 P, and the second

one of the first key h G1 of the circuit of the fszn S - sensor 1a of the arc of the phase C.

The second inputs of the second keys (6) of the chains of phase B and phase C are supplied with signals from the second run of unit 12 of task IIKT of the fuse box. Further passage of the ion b ion in the Phases B and C 1 i Oi chains and the Phase A circuit.

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i i (DZ of the first additional adder TA noi tvnaror signals, npl nopuHOH.uibHbi .-- i OK JM arc of every phase. In ommp Ip Ii the arc current signals are summed i Manilaabuyuyu (coefficient with m, rot H with 1/3). The first input of the first dock of the iggl adder 14 enters the second input of the third additional adder 1b, and from the second output of the first overtake of the total sum of 1A the signal goes to the second input of the first block 18, the output signal of which

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arrive at the input of the power control unit 25, to the second input of the multiplication unit 19 and to the input of the second additional adder 15. The output from the speed controller 26 is fed to the input of the current regulator 27, and the output from the current regulator 27 is fed to the input of the block 8 thyristors.

In order to stabilize the quality of regulation of the system, it is necessary to maintain a constant product of the coefficients, i.e.

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Where

, CL const,

p is the gain of the power regulator; K - the transfer coefficient of the object.

As the furnace warms up, the K value. is falling.

By the magnitude of K ... one can judge the phase and state of melting.

Thus, maintaining at a given level the contour transfer coefficient of the regulation system stabilizes the specified quality (parameters) of transients, and also adjusts the specified (or calculated) electric mode control program, which will further save energy.

Claims (1)

Invention Formula A device for controlling the electric mode of an electric steel arc furnace according to auth.St. ft 1247640, characterized in that, in order to improve the quality of regulation by optimizing the smelting regimes, three are additionally introduced 15 0 five 0 five 0 an adder, a simulation unit, four multiplication units, an integration and storage unit, a program correction unit, the three inputs of the first additional adder are connected to the third outputs of three-phase current sensors, three inputs of the second additional adder are connected to the first additional outputs of the three-phase power controllers, and the output of the second additional adder is connected to the input of the modeling unit, the output of which is connected to the first input of the third additional adder connected by the second input to the first the output of the first additional adder, the output of the third additional adder is connected to the first input of the first multiplication unit, the second input of which is connected to the second output of the first additional adder, and the output of the first multiplication unit is connected to the input of the integration and storage unit, the first three outputs of which are connected to the first inputs the second, third and fourth multiplication units, the second inputs of which are connected to the second additional outputs of the three-phase power controllers, and the outputs of the second, third and The Fourth multiplying units are connected to additional inputs of appropriate regulatory power of three phases tori fourth output integrating unit and the storage connected to the input program correction unit connected to the output from the block input specifying the arc current, a third additional output coupled to an input switch stage voltage of the furnace transformer. With