SU1264379A1 - Power regulator of electric-arc furnace - Google Patents

Abstract

This invention relates to electrical engineering. The aim of the invention is to improve the quality of regulation by increasing the speed and eliminating overshoot when the regulator is working on deviations of the furnace mode from a predetermined value. In a motor circuit, the control laws vary with the nature of the current (intermittent or continuous). The mode of the currents is determined using a filter, and depending on the signal at the output of the filter, the current regulator-npe-g rotates into a proportional-integral link with a continuous current of the motor, and with a discontinuous current into the integral link. 2 hp f-ly, 5 ill.

Description

to

O5 4 CO 1

CO The invention relates to electrothermal, in particular, power regulators of electric arc furnaces, and can be used in electrometallurgy to control the power of electric arc steel-smelting furnaces by moving the electrode. The aim of the invention is to improve the quality of regulation by increasing the speed and eliminating overshoot when the regulator is working on deviations of the furnace mode from a predetermined value. Figure 1 shows the block diagram of the proposed controller; FIG. 2, variants of the regulator; Fig. 3 is a block diagram of the calculation of the root-mean-square value of the arc power (current); figure 4 - diagrams of the keys; figure 5 - diagrams of memory devices. The electric arc power regulator contains an arc power (current) sensor 1, an arc power setpoint (current), whose outputs are connected to the first and second inputs of adder 3, respectively, and the output of the latter is connected to the dead zone unit 4, the output of which is connected the first input of the speed controller 5, the output of the speed controller 5 is connected to the first input of the second adder 6, the first output of which is connected to the first input of the regulator 7 of the current of the electric motor and the second output to the input of the block 8 the maximum current, the output of which is connected to the information input of the key 9, and the control input of the latter is connected to the output of the comparator 10, the first input of which is connected to the output of the reference voltage setting unit 11, and the second input of the comparator 10 is connected to the output of the filter 12, two outputs of the key 9 are connected to the second and third inputs of the current regulator 7, and the code of the current regulator 7 is connected to the third input of the separate control logic 13, the output of which is connected to the input of the reverse thyristor converter 14 connected by the output To the electrical motor 15 main circuit, with the output (shaft) of which the actuator 16 for moving the electrode 18 is connected, a speed sensor 17 is also connected to the shaft of the executive motor 15, the first output of which is connected to the second input of the speed regulator 5, and the second the output is connected to the second input of the separate control logic unit 13, the first input of which is connected to the third output of current executive sensor 19 of the 5G motor 15, the first output of current motor sensor 19 is connected to the second input The second adder 6 and the second output of the motor current sensor 19 are connected to the input of the filter 12, the Regulator (FIG. 2) is additionally equipped with a unit 20 for calculating the continuous root-mean-square power value for a given time interval connected between the output of the power sensor 1 and the input of the first adder 3, and a square root extraction unit connected between the output of the first adder and the input of the deadband unit. Fig. 3 shows the execution of the RMS power calculation unit, which consists of arc power squaring unit 22 (current) in a square, keys 23 - 27 sequentially switching on the resetting keys 28 - 32J reset keys 33 37, key 38 of the initial activation of memory devices, counter 39, the generator 40, the adder 41 and the square root extraction unit 42, when j4eM, the output of the generator 40 is connected to the input of the counter 39, the first output of which is connected to the first input of the key 38, the second, third, fourth, fifth and sixth outputs of the counter 39 s Uniform each with a first input of one of the keys 23 - 27 and to the input key sootvetstzuyuschego 33 - 37 reset. The second input of the key 38 is connected to the first output of the squaring unit 22, the second output of which is connected to the second inputs of the keys 23-27, the outputs of these keys are connected respectively to the first inputs of the storage devices 28-32, the second inputs of which are connected respectively to the outputs of the reset keys 37 , 33, 34, 35, 36, the third inputs are connected to memory devices 28, 29, 30, 31 connected to the output of the key 38, the outputs of the storage devices 28, 29, 30, 31, 32 are connected respectively to the first, second, third, fourth and the fifth inputs of the adder 41, the outputs of which This is connected to the input of the square root extraction unit 42, the output of which is the output of the unit 20, calculating the mean square value of the arc power (current). The power regulator arc furnace works as follows. From the arc power sensor 1, the signal of the actual arc power is fed to the first input of the first adder 3, and a signal from the output of the arc power setpoint 2 is supplied to the second input of the last. The algebraic sum from the output of the first adder 3 is fed to the input of the block 4 of the dead zone. The first adder 3 and the deadband unit 4 are directly connected to the arc power regulator. The static characteristic of the deadband block is proportional with saturation when the electrode is lowered and proportional-relay with crossover and with an adjustable transition point to relay mode. The dead zone of the block is regulated in the range from one to 15% of the nominal value of the arc current. From the output of block 4, the signal goes to the first input of the speed controller 5, the second input of which receives a signal from the first output of the speed sensor 17, which is connected to the shaft, to the electric motor 15 (for example, tachogenerator) or electrically connected to the electric motor core and calculates the angular velocity by its known method. From the output of the speed controller 5, the signal goes to the first input of the second adder 6, the second input of which receives a signal from the second output of the current sensor 19, the adder 6 these signals are algebraically added and this sum is fed to the first input of the current regulator 7. On two Other inputs of the current regulator 7 are connected to the outputs of the switch 9, by which the elements of the feedback circuit of the current regulator are switched, so that when the electric current is constant, it turns into a proportional-integral link, and when the electric current is high, - into an integral unit. The intermittent or continuous current mode is determined using a filter 12, the input of which receives a signal from the first output of the current sensor 19, the reference voltage setting unit 11 and the comparator 10. The key 11 in the intermittent current mode also connects the maximum limiting unit 8 current. The output of the current regulator 7 is fed to the first input of the split control logic unit 13, the second input of which receives a signal from the second output of the speed sensor 17, and the third input from the third output of the current sensor 19. The split control logic unit 13 controls the presence of current in the root circuit of the motor 15, it gives permission to reverse the thyristor converter 14. Depending on the sign of the signal at the output of the current regulator 7, the thyristor converter 14 turns on Forward OR Back, and the magnitude of the signal determines the magnitude the voltage at the output of the thyristor converter 14 and, therefore, at the terminals of the electric motor core 15. The shaft of the electric motor 15 is connected to the actuator 16 (gearbox, kinematic transmission, etc.), which in turn is connected to the electrode 18 of the electric arc furnace and moves it up or down, thus controlling the power (current) of the electric arc. Fig. 2 shows a variant of the power control of an electric furnace for the case when it is necessary to rebuild from short-term disturbances that cause unnecessary displacement of the electrodes, leading to a deterioration of the technical and economic performance of the electric furnace. It also introduced a functional transformation block, which allows to increase the speed of the systems during the development of small displacements. For these purposes, a block 20 for calculating the sliding root-mean-square value of the arc power (current) for the arc, and a block 20 is inserted between the first adder 3 and the block 4 of the dead zone between the first arc gauge (figure 1) and the first sumgtor 3. 21 functional transformations. The unit for calculating the RMS power (current) operates as follows. When the power regulator of the electric arc furnace is turned on, the counter 39 is supplied from the generator 40 with pulses of a given frequency. From the first output of the counter 39, a pulse arrives at the control input of the key 38 of the initial activation of the storage devices 28 5 31. The second input of the key 38 from the first output of the squaring unit 22 receives the square of the current value of the measured parameter and through the key 38 is transmitted to the third inputs of four storage devices 28-31; From the outputs of the storage devices 28 31, the scaled signals arrive at the first four inputs of the adder A1, from the output of which the total signal is fed to the input of the square root extraction unit 42, and at the output At the last one, the signal of the rms initial value of the input parameter, which is fed to the input of the I-31 / p quad block 22, is formed. l.11., V p V 4 V 4 V is the initial value of the measured parameter, is the initial rms value of the measured parameter. At a predetermined time interval t (equal to half or one period of the high frequency component), the key 38 from the second output of counter 30 impulses a pulse to the input of the reset key 37 and the output signal of this key 37 to the second input of the first CD memory 28, clears its from the previously memorized value. At the same time, the pulse from counter 39 goes to the control input of the key 27, which opens, and the square of the measured parameter from the output of the squaring block 22 goes through the key 2 to the first input of the fifth storage device 32, from the output of which the stored signal goes to the fifth the input of the adder 41, from the output of the latter, the sum of squares of the measured parameter is fed to the input of the square root extraction unit 42 and a signal proportional to the root-mean-square value of the measured parameter ipa is generated at the output of this block ni / j: + yi - yi + К 4 At the same interval after a pulse is outputted to the keys 37 and 26, the third output of the counter 39 is pulse 39 is fed to the input of the reset key 33, and the output signal of this key is fed to the second input of the second memory device 29, clearing it from the previously memorized ekachenik. At the same time, a pulse from the third output of the counter 39 is fed to the control input of the key 23, which opens, and the square of the measured parameter value from the output of the squaring block 22 is supplied via the key 23 to the first input of the first storage device 28, from which the stored signal goes to the first the input of the adder 41, ac of the output of the latter, the sum of the squares of the measured parameter is fed to the input of the square root extraction unit 42, and a signal proportional to the root-mean-square is formed at the output of this block Achen sensed parameter. A / yl l sl t-5 -i-5: i-Further, after the interval t after issuing a pulse to the keys 33 and 23 from the fourth output of the counter 39, the pulse arrives at the input of the reset key 34, the output signal of the latter arrives at the second input of the third memory device 30, clearing it from a previously memorized value. At the same time, the pulse from the fourth output of the counter 39 is fed to the control input of the key 24, which opens, and the square of the measured parameter value from the output of the squaring block 22 through the second input and key of the key 24 is fed to the first input of the second storage device 29, the output of which is memorized the signal is fed to the second input of the adder 41, the ac output of the last sum of squares of the measured parameter is fed to the input of the quadratic root extraction unit 42, and a signal proportional to rms value of the measured parameter l. ± Y -V Similarly, the cycles are repeated and at the output of the quadratic root extraction unit 42, the following rms value is obtained

{-yL-l-yi-t- l-t yi

 Zi -.U 1 U and

then

  t-l 4

with. 6, etc.

Thus, the rms value is determined per clock cycle (At), and its update occurs after one cycle C) and the speed of the power control system varies several times.

T (n).

A delay element with a delay of about 2-5 seconds is not required and the delay can be reduced (using the described RMS calculation unit) to 0.25-0.1 s.

Figures 4 and 5 illustrate the operation of the block for calculating the sliding root-mean-square value of the arc power (current) and the diagrams of operation of the keys (figure 4) and memory devices (Fig. 5).

Claims (3)

1. The power regulator of the electric arc furnace containing the first adder connected by the first input with the power sensor, the second input. - with a power setting device, and an output with an input of a dead zone unit connected by an output to the first input of a motor speed controller, the second input of which is connected to a motor speed sensor, a current sensor. the executive motor, the second adder is different. In order to improve the quality of regulation by poking the speed and eliminating overshoot, it is additionally equipped with a maximum current limiting unit, a comparator key element, a reference voltage setting unit, a filter and a separate control logic unit, the output of the motor speed regulator connected to the second an input with a motor current sensor, a first output — with the first input of a current regulator, and a second output — with an input of a max limiting unit Imum current, the output of which is connected to the first input of the key element, connected by two outputs to the second and third inputs of the motor current controller, and the second input of the key element is connected to the output of the comparator, the first input of which is connected to the input of the reference voltage block, and the second input through the filter is connected with the motor current sensor, the output of the motor current controller is connected to the first input of the separate control logic unit, the second input of which is connected to the motor current sensor, third entrance - with. speed sensor, an electric motor, and with the input of a reversible. thyristor and a blower. 2. The regulator according to claim 1, characterized in that it is additionally equipped with a unit for calculating a continuous root-mean-square power value for a predetermined time interval connected between the power sensor and the primary input of the first Adder 3. Controller according to claim 1, characterized in that it is provided with a square root extraction unit connected between the output of the first adder and the input of the dead zone unit. 2 four-/ tt eyftfta fnopy Lh 32