An online real-time tracking control method for electrode adjustment of DC arc furnace

Abstract

The present invention belongs to the technical field of metallurgical equipment and relates to an online real-time tracking control method for electrode adjustment of a DC arc furnace. A sensor collects arc current feedback values, arc voltage feedback values, and electrode column position. An arc current difference is calculated based on an arc current reference value and the collected arc current feedback value. A PID regulator is then used to control a PWM pulse generator to control the operation of a DC power supply device to adjust the output voltage. An arc voltage reference is calculated by subtracting the arc current reference value from the arc current difference. The arc voltage reference value and a dynamic interference value are then summed and subtracted from the collected arc voltage feedback value to obtain an arc voltage difference. The PID regulator then controls a servo valve to adjust the position and lifting speed of the electrode column to perform arc stabilization control. The present invention achieves optimal matching of arc voltage and arc current under different operating conditions during operation of the DC arc furnace, achieving the purpose of online real-time tracking and control of arc voltage and arc current, and significantly suppressing the frequent short circuits and arc breaking problems during operation of the DC arc furnace.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgical equipment, and in particular relates to an online real-time tracking control method for electrode adjustment of a direct current arc furnace. Background Art

[0002] Compared with traditional smelting equipment in the steel industry, DC arc furnaces have the advantages of low energy consumption, low electrode loss, high energy conversion efficiency, significant CO2 emission reduction effects, and low dynamic reactive power compensation requirements. They are important production equipment and development direction for green and intelligent manufacturing in the future steel industry.

[0003] The electrode adjustment automatic control system is the core equipment of DC arc furnace. Its control strategy and action sensitivity directly affect the smelting efficiency and enterprise production benefits. The traditional DC arc furnace electrode lifting control and adjustment system adopts the strategy of voltage closed loop and current closed loop separate control. The electrode lifting control specifically refers to the following: Figure 1 The top cathode in the system shown is controlled to rise or fall, thereby controlling the change in the distance between the top cathode and the bottom anode, and further realizing arc control. However, the above control method severs the connection between arc voltage and arc current when the arc furnace is working. The electrode adjustment system is prone to overshoot or oscillation, resulting in frequent short circuits and arc breaking, affecting the efficiency of arc melting and the quality of the smelted products. In addition, the power output of the DC power supply is difficult to track the melting conditions in the furnace, and the optimal matching energy supply state cannot be achieved. In order to ensure that production conditions are met, it is necessary to maintain high power output continuously, resulting in energy waste. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide an online real-time tracking control method for electrode adjustment of a DC arc furnace, which fully considers the optimal matching relationship between arc voltage and arc current under different working conditions when the DC arc furnace is working, and utilizes a dual closed-loop control strategy of current outer loop and voltage inner loop to achieve the purpose of real-time online tracking control of electrode lifting and lowering adjustment, avoiding the problems of frequent arc breaking caused by the separate control of voltage and current dual closed-loops in the traditional DC arc furnace electrode lifting and lowering control system, and the difficulty in tracking the DC power supply output power to achieve the best matching energy supply.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The following steps are involved:

[0007] S1: The arc current feedback value, arc voltage feedback value and electrode column position are collected by sensors;

[0008] S2: Calculate the arc current difference based on the arc current feedback value and the preset arc current reference value; the arc current difference is obtained by the following formula:

[0009]

[0010] in, is the arc current feedback value obtained after filtering, is the preset arc current reference value, ∆ I The arc current difference between the preset arc current reference value and the arc current feedback value;

[0011] S3: Control the PWM pulse generator through the PID regulator to control the operation of the DC power supply device to adjust the output voltage;

[0012] S4: Calculate the arc voltage reference value according to the arc current reference value and the arc current difference value, then sum the arc voltage reference value and the dynamic interference value and subtract the sum from the collected arc voltage feedback value to obtain the arc pressure difference value;

[0013] The arc voltage reference value is obtained by the following formula:

[0014]

[0015] in, is the preset arc current reference value, K is the impedance matching coefficient of arc voltage and arc current during arc burning at different smelting stages, U ref is the arc voltage reference value;

[0016] The arc voltage difference can be obtained by the following formula:

[0017]

[0018] in, is the dynamic interference value of environmental factors on the arc, is the arc voltage reference value, is the arc voltage feedback value obtained after filtering, It is the arc voltage difference among the arc voltage reference value, dynamic interference action value and arc voltage feedback value;

[0019] S5: The servo valve is controlled by a PID regulator to perform arc stabilization control, wherein the arc stabilization control adopts both a voltage closed-loop control strategy and a current closed-loop control strategy.

[0020] Furthermore, in step S5, the voltage closed-loop control strategy is a voltage inner-loop control strategy, and the voltage inner-loop control strategy includes adjusting the position of the electrode column to be raised or lowered according to the arc voltage difference.

[0021] Furthermore, the voltage inner loop control strategy includes: When , the servo valve is controlled to lift the electrode position; when , control the servo valve to lower the electrode position.

[0022] Furthermore, in step S5, the current closed-loop control strategy is a current outer-loop control strategy, and the current outer-loop control strategy includes adjusting the lifting speed of the electrode column according to the arc current difference.

[0023] Furthermore, the current outer loop control strategy includes: , increase the duty cycle of the PWM pulse generator and increase the output voltage of the DC power supply device; when , reduce the duty cycle of the PWM pulse generator and lower the output voltage of the DC power supply device.

[0024] Furthermore, in step S4, the impedance matching coefficient K The value range is 15~50mΩ.

[0025] The beneficial effects of the present invention are:

[0026] (1) The technical solution provided by the present invention adopts a dual closed-loop control strategy of current outer loop and voltage inner loop, takes the current outer loop as the reference value input of the voltage inner loop, organically combines the arc voltage and arc current control, and realizes the best matching of arc voltage and arc current under different working conditions when the DC arc furnace is working, achieving the purpose of online real-time tracking and control of arc voltage and arc current, and can significantly suppress the frequent short circuit and arc breaking problems when the DC arc furnace is working under the existing electrode adjustment control system, thereby avoiding affecting the efficiency of arc melting and the quality of products.

[0027] (2) The current outer loop is used as the reference value input of the voltage inner loop. The preset arc current reference value can be adjusted in real time according to the smelting status in the furnace, and then the arc voltage reference value is automatically corrected. In addition, the arc voltage and arc current output by the DC power supply device are controlled and adjusted in real time. The power output by the DC power supply device can track the smelting conditions in the furnace in real time to achieve the optimal energy supply state. There is no need to output additional power for a long time, which effectively saves production energy consumption.

[0028] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0030] Figure 1 The system composition of the DC arc furnace described in the background technology of the present invention;

[0031] Figure 2This is a block diagram of the online real-time tracking control method for electrode adjustment of a DC arc furnace according to the present invention.

[0032] Figure 3 This is a comparison chart of the electrode adjustment tracking control method described in the present invention and the single voltage closed-loop and current closed-loop adjustment effects. DETAILED DESCRIPTION

[0033] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0034] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0035] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0036] See also Figure 2 , an online real-time tracking control method for electrode adjustment of DC arc furnace, based on Figure 1 The DC arc furnace shown in FIG comprises the following steps:

[0037] S1: The arc current feedback value, arc voltage feedback value and electrode column position are collected by sensors;

[0038] S2: Calculate the arc current difference based on the arc current feedback value and the preset arc current reference value; the arc current difference is obtained by the following formula:

[0039]

[0040] in, is the arc current feedback value obtained after filtering, is the preset arc current reference value, ∆ I The arc current difference between the preset arc current reference value and the arc current feedback value;

[0041] S3: Control the PWM pulse generator through the PID regulator to control the operation of the DC power supply device to adjust the output voltage;

[0042] S4: Calculate the arc voltage reference value according to the arc current reference value and the arc current difference value, then sum the arc voltage reference value and the dynamic interference value and subtract the sum from the collected arc voltage feedback value to obtain the arc pressure difference value;

[0043] The arc voltage reference value is obtained by the following formula:

[0044]

[0045] in, is the preset arc current reference value, K is the impedance matching coefficient of arc voltage and arc current during arc burning at different smelting stages, K The value range is 15~50mΩ, U ref is the arc voltage reference value;

[0046] The arc voltage difference can be obtained by the following formula:

[0047]

[0048] in, is the dynamic interference value of environmental factors on the arc, is the arc voltage reference value, is the arc voltage feedback value obtained after filtering, It is the arc voltage difference among the arc voltage reference value, dynamic interference action value and arc voltage feedback value;

[0049] S5: The servo valve is controlled by a PID regulator to perform arc stabilization control, wherein the arc stabilization control adopts both a voltage closed-loop control strategy and a current closed-loop control strategy.

[0050] The technical solution provided by the present invention adopts a dual closed-loop control strategy of current outer loop and voltage inner loop, takes the current outer loop as the reference value input of the voltage inner loop, combines arc voltage and arc current control, and realizes the optimal matching of arc voltage and arc current under different working conditions when the DC arc furnace is working, achieving the purpose of online real-time tracking and control of arc voltage and arc current, and can significantly suppress the frequent short circuit and arc breaking problems when the DC arc furnace is working under the existing electrode adjustment control system.

[0051] Based on this preferred solution, the voltage closed-loop control strategy in step S5 is a voltage inner-loop control strategy, which includes adjusting the position of the electrode column to be raised or lowered according to the arc voltage difference. The current closed-loop control strategy is a current outer-loop control strategy, which includes adjusting the lifting speed of the electrode column according to the arc current difference. The voltage inner-loop control strategy includes: when When , the servo valve is controlled to lift the electrode position; when , control the servo valve to lower the electrode position. The current outer loop control strategy includes: , increase the duty cycle of the PWM pulse generator and increase the output voltage of the DC power supply device; when , reduce the duty cycle of the PWM pulse generator and lower the output voltage of the DC power supply device.

[0052] Specifically, the voltage inner loop control strategy and the current outer loop control strategy are simultaneously adopted to perform arc stabilization control, that is, when ∆U>0, ∆I>0, the duty cycle of the PWM pulse generator is increased, the output voltage of the DC power supply device is increased, and the servo valve is controlled to lift the electrode at a speed less than 0.2 m / s; when ∆U>0, ∆I<0, the duty cycle of the PWM pulse generator is reduced, the output voltage of the DC power supply device is reduced, and the servo valve is controlled to lift the electrode at a speed greater than 0.5 m / s; when ∆U<0, ∆I>0, the duty cycle of the PWM pulse generator is increased, the output voltage of the DC power supply device is increased, and the servo valve is controlled to lower the electrode at a speed greater than 0.5 m / s; when ∆U<0, ∆I<0, the duty cycle of the PWM pulse generator is reduced, the output voltage of the DC power supply device is reduced, and the servo valve is controlled to lower the electrode at a speed less than 0.2 m / s.

[0053] This solution utilizes the control strategy of the current outer loop and the voltage inner loop, and uses the output of the current outer loop as the input of the voltage inner loop, organically linking the arc voltage and arc current of the DC arc furnace. By correcting the preset arc current reference value according to the changes in the working conditions in the DC arc furnace, the optimal matching relationship between the arc voltage and arc current can be corrected in real time, realizing online tracking control and achieving the control purpose of intelligent arc stabilization by electrode regulation.

[0054] Figure 3 This is a comparison chart of the regulation effects of single voltage closed-loop regulation, single current closed-loop regulation, and the current outer loop and voltage inner loop provided by the present invention. The method provided by the present invention can effectively reduce the overshoot of voltage and current in the regulation process, reduce the current peak value, smooth the fluctuation of voltage and current in the regulation process, and better ensure the stability and continuity of arc combustion in the smelting process.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for online real-time tracking control of electrode adjustment for a DC arc furnace, characterized by: The following steps are involved: S1: The arc current feedback value, arc voltage feedback value and electrode column position are collected by sensors; S2: Calculate the arc current difference based on the arc current feedback value and the preset arc current reference value; The arc current difference is obtained by the following formula: in, is the arc current feedback value obtained after filtering, is the preset arc current reference value, ∆ I The arc current difference between the preset arc current reference value and the arc current feedback value; S3: Control the PWM pulse generator through the PID regulator to control the operation of the DC power supply device to adjust the output voltage; S4: Calculate the arc voltage reference value according to the arc current reference value and the arc current difference value, then sum the arc voltage reference value and the dynamic interference value and subtract the sum from the collected arc voltage feedback value to obtain the arc pressure difference value; The arc voltage reference value is obtained by the following formula: Among them, I set is the preset arc current reference value, K is the impedance matching coefficient of arc voltage and arc current during arc burning at different smelting stages, U ref is the arc voltage reference value; The arc voltage difference can be obtained by the following formula: in, is the dynamic interference value of environmental factors on the arc, is the arc voltage reference value, is the arc voltage feedback value obtained after filtering, It is the arc voltage difference among the arc voltage reference value, dynamic interference action value and arc voltage feedback value; S5: The servo valve is controlled by a PID regulator to perform arc stabilization control, wherein the arc stabilization control adopts both a voltage closed-loop control strategy and a current closed-loop control strategy.

2. The method for online real-time tracking control of electrode adjustment of a DC arc furnace according to claim 1, characterized in that: In step S5, the voltage closed-loop control strategy is a voltage inner-loop control strategy, and the voltage inner-loop control strategy includes adjusting the position of the electrode column to be raised or lowered according to the arc voltage difference.

3. The method for online real-time tracking control of electrode adjustment of a DC arc furnace according to claim 2, characterized in that: The voltage inner loop control strategy includes: When , the servo valve is controlled to lift the electrode position; when , control the servo valve to lower the electrode position.

4. The method for online real-time tracking control of electrode adjustment for a DC arc furnace according to claim 1, characterized in that: In step S5, the current closed-loop control strategy is a current outer-loop control strategy, and the current outer-loop control strategy includes adjusting the lifting speed of the electrode column according to the arc current difference.

5. The method for online real-time tracking control of electrode adjustment of a DC arc furnace according to claim 4, characterized in that: The current outer loop control strategy includes: , increase the duty cycle of the PWM pulse generator and increase the output voltage of the DC power supply device; when , reduce the duty cycle of the PWM pulse generator and lower the output voltage of the DC power supply device.

6. The method for online real-time tracking control of electrode adjustment of a DC arc furnace according to claim 1, characterized in that: In step S4, the impedance matching coefficient K The value range is 15~50mΩ.

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