SU1228307A1 - Power controller of electric-arc furnace - Google Patents

Abstract

The invention relates to electrical engineering, in particular to power regulators of the mode of arc steelmaking furnaces with electric and hydraulic drives. The purpose of the invention is to increase the productivity of the furnace by reducing the melting time and reducing the specific energy consumption due to a more stable input of power into the electrophysical zone of the arc discharge. The device contains current sensors 1 and voltage 2 on an arc, a comparison unit 3, a control unit for driving the movement of electrodes 7. Introduction of adder A, switch (K) 5, second comparison unit 8, key 10, integrator 11 with two variable variables the gain (MIC) 9 and 6 gain and the memory and the block of task 12 ensure the maintenance of a constant total gain of the automatic control system. When the electrical mode is violated, the error signal after BS 3 is not zero, K 5 locks key 10 and information about changes in the parametric disturbances of the object is not received, although they change continuously. To save the previous values of the coefficients in the MIC 9 and 6, a memory block is inserted. 1 il. (L

Description

one

The invention relates to electrical engineering, in particular, to power regulators of the electric mode of electric arc steel-smelting furnaces of various capacities with electric and hydraulic drives.

The purpose of the invention is to increase the furnace productivity by reducing the melting time and reducing the specific energy consumption due to the stable input of power into the electrical area of the arc discharge.

: The drawing shows a block diagram of the proposed automatic power control of electric arc steel-smelting furnaces.

The device contains current sensors 1 and voltage 2 on the arc, the outputs of which are connected to the inputs of the first comparison unit 3 and adder 4. The output of the first comparison unit 3 is connected to the switch 5 and the first block 6 with variable gain and memory. The output of the latter is connected to the electrode drive control unit 7. The output of the adder 4 is connected to the first input of the second comparison unit 8, the second input of which is connected to the output of the second block 9 with variable gain and memory. The output of the comparison unit 8 is connected via the key 10 to the input of the integrator 11. The second input of the key 10 is connected to the output of the switch 5. The output of the block 11 is connected simultaneously to the second inputs of blocks 9 and 6. The first input of the block 9 is connected to the output of the task block 12.

The device works as follows.

The measured signals from current sensors 1 and voltage 2 are compared with each other in block 3 and simultaneously summed up in block 4. Differential signal from block 3 is fed to block 7 controlling the drive of the electrode movement and to key 10 through switch 5. A summed signal from the block. 4 goes to block 8, where it is compared with a set point of block 12, matched with the voltage level of the furnace transformer,. The signal from block 8 through the output of key 10 goes to integrator 11, and then to the inputs of blocks 9 and 6 with variable gain and memory tew.

The essence of the work of the proposed scheme is to maintain a constant

S

five

0

five

0

3

0

five

07, I

The overall gain factor Kc; the system1: .1 automatic control by the electric mode, based on the need for the stability of its operation as a whole, as well as economic considerations, i.e.

K. „Kr-K„ SOP81, (1)

where K ,, K - gain factors

controller and object, respectively.

This is provided as follows. During normal operation of the furnace (the error signal after the comparison block 3 is zero), the regulator is inactive, i.e. the nominal length of the arc is maintained, corresponding to a predetermined voltage level of the furnace transformer. At the same time, the parameters of the object (coe (3x |)

current and voltage transmissions

KYL changes as a result of

Changes in arc burning conditions. For small deviations of the system parameters, when the signals from the current and voltage sensors are equal, their sum determines the necessary information about the complete change in the object gains. After comparing in block 8 the resulting sum signal from block 4 with its established value, in a certain sense optimal (signal of block 12), information is found about the deviation of object parameters to one side or the other, which then, in integrator 11, summarizes the switch 5 and the key 10, translates the gain values of the controller Kp (in block 6) and the assignments Kj (in block 9) to another value until the deviation disappears after block 8, i.e. until equality (1) is fulfilled.

When the electric mode fails (the error signal after block 3 is not zero), as well as in critical situations (short circuit or interruption of the arc), when only one signal is present, either by current or voltage, the switching element 5 locks the key 10 and information about changes in the parametric perturbations of the object is not received, although they are unambiguously changing. Therefore, in order to preserve the previous value of the coefficients in blocks 9 and 6, a memory block is inserted.

When switching the voltage levels of the furnace transformer, the value of the setting of the block 12 and the controller-works according to the indicated principle changes accordingly.

The use of the proposed automatic power regulator for electric arc furnaces leads to an increase in the dynamic accuracy of the development of parametric | and coordinate perturbations (its potential increases) and to a significant reduction in critical situations - open arcs and short circuits (decreased carburization of the fusible metal, i.e., its quality is improved). The use of this regulator allows to increase the productivity of the furnace due to the desired process flow, as well as to reduce the specific energy consumption by increasing the stability of the controller as a whole.

Claims (1)

Invention Formula The automatic power regulator of an electric arc furnace, containing current and voltage sensors on the arc, connected by outputs to the corresponding inputs of the first comparator unit, and an electrode movement actuator control unit, different Compiled by E.Kosarev Editor N.Kishtulinets Tehred I.Vere Corrector S.Shekmar Order 2299/60 Circulation 765 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4 In order to increase furnace productivity by reducing melting time and reducing specific power consumption, it is additionally equipped with a summing block, a key, a switch, a second comparison block, an integrator, two variable gain blocks and a memory and a block of reference, This output of these sensors through a summing unit connected to the first input of the second unit of comparison, the output of which is connected to the first input of the key, the second input of which through the switch is connected to the output of the first the comparison unit, the output of the key is connected to the input of the integrator, the output of which is connected to the second inputs of the first and second blocks with variable gain and memory, the first input of the first block with variable gain and memory is connected to the output of the first comparison block, and the output is the input of the drive control unit, the first input of the second unit with variable gain and memory is connected to the output of the task unit, and the output to the second input of the second comparison unit.