Energy-saving control method for hydraulic system of hot continuous rolling production line

Abstract

This invention relates to the field of energy-saving technology for strip rolling equipment, specifically disclosing an energy-saving control method for the hydraulic system of a hot continuous rolling production line. The method includes: energy-saving control of a hydraulic servo pump group using a servo motor + variable pump system; closed-loop hydraulic control using a PLC controller to adjust the servo motor speed; optimized multi-pump parallel operation control based on the actual needs of different hydraulic stations; and optimized equipment parameters by optimizing the servo driver. This invention achieves energy-saving effects through precise control of the servo motor, enabling the pump group to start and stop at any time and supply power on demand without overflow, thus achieving a balance in hydraulic system pressure supply, reducing power consumption, improving production economy, and increasing response speed.

Description

Technical Field

[0001] This invention relates to the field of energy-saving technology for strip rolling equipment, specifically to an energy-saving control method for the hydraulic system of a hot continuous rolling production line. Background Technology

[0002] Hydraulic systems, as an indispensable power core in the 2250 hot strip rolling production process, are widely used in various key stages such as the rolling line. Traditional hydraulic systems generally suffer from drawbacks such as high energy consumption, low load rate, high oil temperature, high noise, and slow response. Specifically, for example... Figure 2 As shown, the traditional asynchronous motor + fixed displacement pump system provides a constant supply. When the hydraulic cylinder stops moving, the motor-pump unit continues to operate, and all the output energy is unloaded through the relief valve, resulting in significant energy waste. Figure 3 As shown, while the asynchronous motor + variable pump system achieves supply changes, the asynchronous motor cannot completely stop, resulting in idling and wasted reactive power. In the current context of enterprises continuously promoting energy conservation, emission reduction, cost reduction, and efficiency improvement, exploring the energy-saving potential of hydraulic systems is of great significance for achieving green and low-carbon development and improving economic efficiency. Traditional hydraulic systems generally suffer from high energy consumption, low load rate, high oil temperature, high noise, and slow response. Therefore, it is necessary to design an energy-saving control method for the hydraulic system of a hot strip rolling production line to solve the problems of high energy consumption and slow response in existing traditional hydraulic systems of hot strip rolling production lines. Summary of the Invention

[0003] In view of the problems existing in the prior art, the purpose of this invention is to provide an energy-saving control method for the hydraulic system of a hot strip rolling production line.

[0004] The technical solution adopted by this invention to solve its technical problem is: an energy-saving control method for a hydraulic system of a hot strip mill production line, comprising the following steps:

[0005] S1. Energy-saving control of hydraulic servo pump group: adopts servo motor + variable pump system;

[0006] S2, Hydraulic closed-loop control: Through the hydraulic closed-loop control mode, the PLC controller controls the servo driver to adjust the servo motor speed;

[0007] S3. Multi-pump parallel operation optimization control: Optimize the multi-pump parallel operation strategy according to the actual needs of different hydraulic stations;

[0008] S4. Device parameter optimization: Optimize the servo driver.

[0009] Specifically, in step S1, the servo motor is connected to the variable pump controller, the variable pump controller is connected to the actuator through the valve, and the control end of the servo motor is connected to the servo driver.

[0010] Specifically, the actuator includes a high-pressure hydraulic station pump unit for finishing mill and a hydraulic station pump unit for roughing mill. Each actuator is equipped with a pressure sensor, which is connected to a servo driver. The servo driver is connected to a PLC controller, which is connected to a display. The servo driver controls a servo motor to control the start-up and shutdown of the high-pressure hydraulic station pump unit for finishing mill and the hydraulic station pump unit for roughing mill, as well as to supply power as needed.

[0011] Specifically, the process of the hydraulic closed-loop control mode in step S2 is as follows: before the set pressure is reached, the servo driver executes the speed closed-loop control mode, and the servo motor runs at the set maximum speed; after the set pressure is reached, the servo driver executes the pressure closed-loop control mode, and the servo motor system maintains constant pressure and adaptive speed.

[0012] Specifically, the multi-pump parallel operation strategy in step S3 involves dynamically adjusting the number and speed of the pumps in the finishing mill high-pressure hydraulic station pump group and the roughing mill hydraulic station pump group based on flow requirements and pump group efficiency.

[0013] Specifically, the optimization of the servo driver in step S4 includes increasing the inductance of the DC reactor on the rectifier bridge side for 30kW and above; adopting the fourth-generation KT4 module for the IGBT module; designing a braking electrical circuit; and incorporating a built-in detection module for intelligent detection for 75kW and below; and using an ESMY model servo motor paired with a constant pressure variable piston pump.

[0014] The present invention has the following beneficial effects:

[0015] The present invention relates to an energy-saving control method for the hydraulic system of a hot rolling mill production line. Through the precise control of a servo motor, the pump group can be started and stopped at any time and supplied on demand without overflow, thereby achieving energy-saving effect, realizing the pressure balance of the hydraulic system, reducing power consumption, improving production economy, and increasing response speed. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the control structure for an energy-saving control method of the hydraulic system in a hot strip mill production line.

[0017] Figure 2 This is a schematic diagram of the control structure of an asynchronous motor + fixed displacement pump system in existing technology.

[0018] Figure 3 This is a schematic diagram of the control structure of an asynchronous motor + variable pump system in existing technology.

[0019] Figure 4 This is a control flowchart regarding energy-saving control methods for the hydraulic system of a hot strip mill production line.

[0020] Figure 5This is a schematic diagram of the response curves comparing the present invention with the prior art.

[0021] Figure 6 This is a schematic diagram of the skill rate of a metallurgical hydraulic station compared with existing technologies.

[0022] In the diagram: 1-Servo motor; 2-Servo driver; 3-Valve; 4-Actuator; 5-Asynchronous motor; 6-Fixed displacement pump controller; 7-Variable displacement pump controller; 8-Pressure sensor; 9-PLC controller; 10-Display. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] like Figure 1 and Figure 4 As shown, an energy-saving control method for the hydraulic system of a hot strip mill production line includes the following steps:

[0025] 1. Energy-saving control of hydraulic servo pump group: adopts servo motor 1 + variable pump system; servo motor 1 is connected to variable pump controller 7, variable pump controller 7 is connected to actuator 4 through valve 3, and the control end of servo motor 1 is connected to servo drive 2.

[0026] Actuator 4 includes a high-pressure hydraulic station pump unit for the finishing mill and a hydraulic station pump unit for the roughing mill. Each actuator 4 is equipped with a pressure sensor 8, which is connected to a servo driver 2. The servo driver 2 is connected to a PLC controller 9, and the PLC controller 9 is connected to a display 10. The servo driver 2 controls a servo motor 1 to control the start-up and stop of the high-pressure hydraulic station pump unit for the finishing mill and the hydraulic station pump unit for the roughing mill, and to provide power as needed. Through the precise control of the servo motor 1, the pump units can be started and stopped at any time and supplied power as needed, with almost no overflow, thus achieving energy-saving effects.

[0027] 2. Hydraulic Pressure Closed-Loop Control: Through hydraulic pressure closed-loop control, the PLC controller 9 controls the servo drive 2 to adjust the speed of the servo motor 1 to meet the on-site pressure requirements. Specifically, before reaching the set pressure, the servo drive 2 executes speed closed-loop control mode, and the servo motor 1 runs at the set maximum speed; after reaching the set pressure, the servo drive 2 executes pressure closed-loop control mode, and the servo motor 1 system maintains constant pressure and adaptive speed, achieving precise supply of "just the amount needed."

[0028] 3. Multi-pump parallel operation optimization control: Optimize the multi-pump parallel operation strategy according to the actual needs of different hydraulic stations; in the scenarios of high-pressure hydraulic station pump group in finishing mill and hydraulic station pump group in roughing mill, dynamically adjust the number and speed of the operating pumps based on flow requirements and pump group efficiency to ensure that the system operates in the high-efficiency range.

[0029] 4. Equipment Parameter Optimization: Software and hardware optimizations were performed on the servo drives. On the software side, the field weakening control level was improved by 10%, employing a software algorithm with stronger response and impact suppression capabilities. On the hardware side, for rectifiers above 30kW, the inductance of the DC reactor was increased, and its specifications were upgraded to enhance protection of the rectifier bridge; the IGBT module adopted the fourth-generation KT4 module, extending its lifespan to 2.5 to 3 times that of the third-generation KT3; the overall bus capacitor was upgraded to a high-temperature, long-life capacitor, theoretically increasing its lifespan by 4 times; a braking electrical circuit was designed, and a built-in detection module was incorporated for intelligent detection in servo drives below 75kW; servo drive 2 is an ES660 servo drive, and servo motor 1 adopts the ESMY model servo motor 1, paired with a constant-pressure variable displacement piston pump to improve energy conversion efficiency.

[0030] Supply and demand balance control based on production cycle time: This involves dynamically adjusting the hydraulic system's supply flow and pressure based on the specific cycle time of billet rolling in hot continuous rolling production. Sufficient hydraulic power is provided during equipment operation, while the supply is reduced during standby to avoid energy waste.

[0031] This invention employs a servo motor + variable pump system to achieve real-time start / stop and on-demand supply of the pump unit. Through a hydraulic closed-loop control mode, a PLC controller controls the servo driver to adjust the motor speed to meet on-site pressure requirements. Speed ​​closed-loop control is executed when the set pressure is not reached, and pressure closed-loop control is executed after the set pressure is reached. The invention optimizes the multi-pump parallel operation strategy, dynamically adjusting the number and speed of operating pumps based on flow demand and pump unit efficiency. Software and hardware optimizations are performed on the servo driver 2 to improve system response and stability. The supply flow and pressure of the hydraulic system are dynamically adjusted in conjunction with the production cycle. This dynamic adjustment based on the production cycle adjusts the operating parameters of the hydraulic system according to the rolling line's production status (steel passing, roll changing, maintenance, rolling stoppage, etc.) to achieve supply and demand balance.

[0032] The sensor unit collects the system's pressure and speed parameters in real time and feeds them back to the PLC control unit. The PLC control unit generates control signals based on the feedback data and production status to drive the servo drive unit.

[0033] like Figures 5-6 As shown, the hydraulic servo system implemented by the technical solution of the present invention has a speed response of less than 100ms, which is faster in terms of flow response and shorter in terms of pressure replenishment time compared with the traditional method, and has a significant energy-saving effect.

[0034] Example 1

[0035] 1. System Configuration: Energy-saving retrofitting of multiple hydraulic stations on the 2250mm hot strip mill production line, including the finishing mill high-pressure hydraulic station, finishing mill low-pressure hydraulic station, coiling hydraulic station, width sizing mill hydraulic station, roughing mill high-pressure hydraulic station, and roughing mill low-pressure hydraulic station. The original configurations of each hydraulic station are as follows:

[0036] Heating furnace hydraulic station: 6 132kW motors, 3 hydraulic stations, each station operates 5 motors at a time;

[0037] Hydraulic station for width fixing machine: 3 x 132kW motors, 2 motors in continuous operation;

[0038] Low-pressure hydraulic station for roughing mill: 5 motors of 160kW each, with 3 motors in continuous operation;

[0039] High-pressure hydraulic station for roughing mill: 7 motors of 200kW each, with 5 motors in continuous operation;

[0040] Low-pressure hydraulic station for finishing mill: 5 motors of 160kW each, with 4 motors in continuous operation;

[0041] High-pressure hydraulic station for precision rolling: 7 motors of 200kW each, with 5 motors in continuous operation;

[0042] Winding hydraulic station: 6 motors of 160kW each, with 5 motors in continuous operation;

[0043] Hydraulic station for transport line: 7 x 160kW motors, 4 of which are in continuous operation.

[0044] 2. Application of energy-saving control methods:

[0045] The motors and pump sets of each hydraulic station are modified to replace the traditional asynchronous motor + fixed displacement pump or variable displacement pump system with a servo motor 1 + variable displacement pump system, such as ESMY servo motor 1 paired with a constant pressure variable displacement piston pump.

[0046] Install ES660 servo driver 2, and optimize the software and hardware of driver 2 to improve the field weakening control level and system response capability.

[0047] Deploy pressure sensors 8, speed sensors, etc., to build a closed-loop hydraulic control system, and achieve precise control of system pressure and flow through PLC controller and host computer.

[0048] Establish a supply and demand balance control model based on production cycle time, and dynamically adjust the operating parameters of the hydraulic system according to the production status of the rolling line (such as steel passing, standby, etc.).

[0049] 3. Energy Saving Effect: After the upgrade, the energy consumption of each hydraulic station was significantly reduced. Taking the finishing mill low-pressure hydraulic station as an example, the daily servo power consumption was 1604.2 kWh, and the daily power frequency power consumption was 2784.6 kWh, resulting in a power saving of 1180.4 kWh, a saving percentage of 42.4%. Calculations of the power consumption per ton of steel in hydraulic mode and constant speed mode of the finishing mill low-pressure hydraulic station showed that hydraulic mode saves approximately 49% more power than constant speed mode. The entire hydraulic system can save approximately 0.55 kWh / ton of steel per year, achieving significant energy saving and economic benefits.

[0050] This invention is not limited to the above-described embodiments. Anyone should know that any structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention.

[0051] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. An energy-saving control method for a hydraulic system in a hot strip mill production line, characterized in that, Includes the following steps: S1. Energy-saving control of hydraulic servo pump group: adopts servo motor + variable pump system; S2, Hydraulic closed-loop control: Through the hydraulic closed-loop control mode, the PLC controller controls the servo driver to adjust the servo motor speed; S3. Multi-pump parallel operation optimization control: Optimize the multi-pump parallel operation strategy according to the actual needs of different hydraulic stations; S4. Device parameter optimization: Optimize the servo driver.

2. The energy-saving control method for the hydraulic system of a hot strip mill production line according to claim 1, characterized in that, In step S1, the servo motor is connected to the variable pump controller, the variable pump controller is connected to the actuator through the valve, and the control end of the servo motor is connected to the servo driver.

3. The energy-saving control method for the hydraulic system of a hot strip mill production line according to claim 2, characterized in that, The actuator includes a high-pressure hydraulic station pump unit for finishing mill and a hydraulic station pump unit for roughing mill. Each actuator is equipped with a pressure sensor, which is connected to a servo driver. The servo driver is connected to a PLC controller, which is connected to a display. The servo driver controls a servo motor to control the start-up and stop of the high-pressure hydraulic station pump unit for finishing mill and the hydraulic station pump unit for roughing mill, and to supply hydraulic power as needed.

4. The energy-saving control method for the hydraulic system of a hot strip mill production line according to claim 3, characterized in that, The specific process of the hydraulic closed-loop control mode in step S2 is as follows: before the set pressure is reached, the servo driver executes the speed closed-loop control mode, and the servo motor runs at the set maximum speed; after the set pressure is reached, the servo driver executes the pressure closed-loop control mode, and the servo motor system maintains constant pressure and adaptive speed.

5. The energy-saving control method for the hydraulic system of a hot strip mill production line according to claim 3, characterized in that, The multi-pump parallel operation strategy in step S3 involves dynamically adjusting the number and speed of the pumps in the finishing mill high-pressure hydraulic station pump group and the roughing mill hydraulic station pump group based on flow requirements and pump group efficiency.

6. The energy-saving control method for the hydraulic system of a hot strip mill production line according to claim 3, characterized in that, The optimization of the servo driver in step S4 includes increasing the inductance of the DC reactor on the rectifier bridge side for 30kW and above; adopting the fourth-generation KT4 module for the IGBT module; designing a braking electrical circuit; and incorporating a built-in detection module for intelligent detection for 75kW and below; and using an ESMY model servo motor paired with a constant pressure variable piston pump.

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