Brief introduction of automatic control system for

2022-07-22
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Introduction to the automatic control system of 60t converter

1.1 introduction to converter process

the bulk materials will be sent to the top silo of the converter from the low-level silo by four belt conveyors; The converter body is the core part of the whole converter system. It is mainly used for oxygen blowing and steelmaking. When the converter is blown to 1700 ℃, the molten steel is discharged to the ladle behind the furnace, then the nitrogen is blown to the converter, the slag is splashed to protect the furnace, and then the slag is discharged to the front of the furnace; After the molten steel is poured into the ladle, argon is blown at the top or bottom of the molten steel through the argon blowing station (the function is to mix the molten steel evenly so that the slag in the molten steel floats on the surface to ensure smooth continuous casting casting), and the safety protection net is provided to the steel; Adding alloy into the water to adjust the composition of molten steel; The flue gas from the converter is mainly discharged through two dedusting systems: the primary dedusting system exhausts from the converter hood through the high-pressure fan. When the converter is blown, the flue gas will not overflow from the mixture of sulfuric acid and vanadium. Moreover, according to the analysis of the gas composition, the flue gas from the converter can be dispersed or recycled to the gas tank through the valve group in the fan room. The secondary dedusting system passes through the high-pressure fan, Extract the flue gas from the crown block when pouring molten steel to the converter: the circulating water pump room supplies water to the whole steelmaking plant through the pump unit. The converter is mainly composed of cooling water for oxygen lance; The post furnace ferroalloy system processes the alloy to be added to the ladle through the baking furnace

1.2 overview of system composition

the framework idea of the system is to use a PLC substation to control the centralized equipment. If the distance is relatively close, the PLC mainframe expansion method is adopted (6 can be expanded at most, and the expansion racks can be up to 2 meters); If the system settings are scattered, the remote rack is used to form a distributed control system. A communication module is configured on the master station, and the master station and the remote station are connected by genius line

the master station of the system uses ge90.30 series PLC, and the substation uses VersaMax. The master station and the substation communicate and transmit data through genius bus; Each subsystem is connected by optical fiber to form an optical fiber ring, which ensures the speed and reliability of data exchange; ABB frequency converter is used to control oxygen lance, tilting, ladle car and slag tank car of converter

system software configuration: the operating system of the industrial computer is Windows 2000 SP4, the programming software is versapro 2.03, but its strength is 5 times, and the HMI monitoring software is Cimplicity 6.1. System hardware configuration: the master station includes power module, CPU module and Ge series Di, do, AI and AO modules in different quantities, and the system connected to the substation also includes a communication module; The substation includes power modules, Niu modules and VersaMax series Di, do, AI and AO modules in different quantities

framework of three distributed systems:

the converter body is a ge90.30 master station connected to three VersaMax sub stations. In front of the main station control furnace, each (including main control console, converter tilting, oxygen lance lifting, thin oil station, fire door, etc.); 1shan} station is located in the main control room. We welcome industry elite enterprises to assist this conference to control the bottom blowing valve station (including the flow and pressure of bottom blowing argon and nitrogen); 2 mixing sub station is set on the 21.5m platform to control the feeding of the converter's vibrating silo (including the start, stop and weight signal display of ten vibrating silos): 3 sub station is set on the 31.5m platform to control the top blowing valve station (including the flow pressure of oxygen lance cooling water, top blowing oxygen and nitrogen, drum water level and oxygen lance traverse trolley)

bulk material is a ge90.30 master station connected to a VersaMax substation. The master station controls the bottom bin equipment (including 1 group, 2 belt conveyors and underground receiving trough vibrating hopper): 1 substation is set at the 36.5m platform to control the high bin (3 and 4 belt conveyors, furnace top bin dust removal electric butterfly valve and unloading trolley)

one GE90-30 master station is connected to two VersaMax substations for primary dedusting. Main equipment of main station control fan room (including primary dust removal fan, gas recovery or release valve group, igniter and flushing valve); 1fi1 substation is set at the 27.5m platform to control the flue gas purification system (including the pressure at the throat of Erwen, the flow and pressure of the water supply of Yiwen and Erwen): 2 substation is set at the soft water station to control the start and stop of three soft water pumps

2 system communication network

the CPU module of Antai converter is ic693cpu374. Cpu374 has a 10/100M Ethernet card (integrated with CPU) and two RJ45 interfaces (one II) address). The CPU supports Ethernet broadcast mode communication (EGD mode), and only needs to make simple send and receive settings during CPU hardware configuration

since signal transmission and data exchange must be carried out among the ten subsystems (for example, converter body and og fan room, og fan room and gas holder, etc.), each subsystem is equipped with an inlet industrial switch during system configuration. Each system is connected through optical fiber head and tail to form an optical fiber ring. The network diagram of the system is as follows (as shown in Figure 1): characteristics of the optical fiber ring: the optical fiber ring structure is composed of point-to-point links, and the point-to-point optical fiber transmission technology is the most mature, so the optical fiber ring structure is the most common. In this structure, the delay of optical fiber is small, and it is easy to configure rings and high-speed rings at many sites

3 ABB frequency converter

ABB frequency converter (acss00 Series) is used to control the oxygen lance, tilting and ladle car (slag tank car) of Antai converter. The core technology of ABB Inverter is true torque control (DTC). DTC control is an optimal motor control method for AC drive. It can directly control the core variables of all AC motors. DTC control is a revolution in the motor control mode in the AC drive field. It can realize the accurate control of motor speed and torque without using the pulse code disk feedback on the motor shaft from zero speed. The control idea of frequency converter: after the upper computer receives the "accurate and good" signal from the frequency converter, The corresponding start command can be sent through PLC. When the transmission device acts, the frequency converter can return the running status signal of the equipment to PLC and display it on the upper computer

due to the different uses of oxygen lance, tilting and ladle car (slag tank car) frequency converter, there are corresponding differences in parameter settings. The key is that the application macros selected by the frequency converter corresponding to the three different applications are different. The lifting control of oxygen lance requires the use of crane control, the tilting control of converter requires the use of torque macro (t-ctrl), and the front and rear control of ladle car (slag tank car) requires the use of factory control

since the tilting control of converter adopts the mode of four frequency converters driving four motors, the master-slave (masterjfollo, Ⅳ ER) control mode is the most reasonable. Four frequency converters are connected by optical fiber to form a ring. Two sets of different parameters (one set of master parameters and one set of slave parameters) are set for each frequency converter. The master adopts speed control and the slave adopts torque control, which are stored in two users (useri and user2) for calling. One frequency converter calls the master parameter user1, and the other three call the slave parameter user2. At this time, when one or two of the three slaves fail, the tilting system can still operate normally; If the host fails, the master/slave parameters of four frequency converters must be switched on the upper computer, and one of the slave computers must be switched to the host computer to ensure the normal operation of the system. That is to ensure that at least one slave and the master are normal

characteristics of master/slave control: the master/slave function is designed for multi drive applications. The system is driven by several acss00 frequency converters, and the motor shafts are coupled together through gears, chains or conveyor belts. Due to this master/slave function, the load can be evenly distributed among the transmission units. The external control signal is only connected to the host. The master controls the slave through an optical fiber serial communication link

the main engine is a typical speed control, and other transmission units follow the torque or speed setting of the main engine. Generally:

● when the motor shafts of the master and the slave are rigidly connected through gears, chains, etc., the slave should adopt the torque control mode so that there is no speed difference between the transmission units

● when the motor shafts of the master and the slave are flexibly connected, the slave should adopt the speed control mode, because small speed differences are allowed between the transmission units

converter tilting motor is rigidly connected, so torque control is applied to the slave here

4 some experiences

first, on-site commissioning service can train a technician's ability to handle things calmly in a tense commissioning environment

second. Site commissioning shall be conducted carefully. Before the power transmission of the frequency converter, the wiring must be checked according to the hardware wiring Manual of the frequency converter: the same is true when the PLC system is powered on. Pay special attention to the power supply of the ~uplc module. Refer to the module wiring diagram, and distinguish between AC220V and DC24V. Do not string wires, otherwise the fuse will be burnt out or the module will be burnt out, causing serious consequences

third, the basic automation level of the control system adopts industrial Ethernet, and 10 operation stations mainly complete the collection and processing of process data, operation, monitoring, control and alarm of production process. The optical fiber is used as the network communication medium and forms a 10/100M optical fiber ring. The CPU module of PLC can be directly linked into the optical fiber Ethernet ring to become an Ethernet node. It has the advantages of high transmission rate and strong compatibility, and is convenient for the realization of the upper network

fourth, combined with the site conditions. There are also deficiencies in the composition of the system. The 2 sub station (soft water station) of primary dust removal should be incorporated into the 3 Han sub station of the converter body system, because the 2 Han sub station of primary dust removal only controls the three soft water pumps of the soft water station, while other flows and pressures enter the body system, and the operation of the primary dust removal control room is groundless

the upper computer picture of Antai converter automation control system is compiled through cimplicity6.1, which has completed the functions of upper computer monitoring, operation and data acquisition. The system picture is humanized, the operation is intuitive and convenient, and all equipment working states are displayed on the upper computer, which is easy to maintain

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