This article analyzes the automation control system of the Southwest Stainless 1450mm hot-rolled strip production line and elaborates on the basic structure, control functions and other aspects of the hot-rolled strip production line automation control system to provide a reference for similar projects in the future.
The 1450 hot-rolled stainless steel strip production line of Southwest Stainless Steel Co., Ltd. is a relatively advanced strip production line with a leading level of automation.
1) Overall configuration of the system
In recent years, as the requirements for rolling final products have become more and more stringent, people’s requirements for rolling processes and control technology have also increased accordingly. Therefore, it is necessary to adopt a multi-level automated control system to comprehensively and effectively control the production process. The large amount of information exchange between control systems at all levels requires more advanced organizational management. Therefore, the characteristics and functional configuration of the equipment require cooperation between several automation levels. The Southwest Stainless 1450 hot-rolled strip automation control system can be divided into three levels, namely: transmission level (level 0), basic automation level (level 1), and process automation level (level 2), with the same heating furnace and continuous casting Automation system and level 3 automation system interface.
An important feature of this classification is the range of functions included within each level itself. The scope of functions included in it refers to after installation at each level, the operator can operate the equipment according to its corresponding level. The term also means that the interfaces between the levels are minimal. The simplification of maintenance personnel’s operations during the production process and the advantages brought by this design method cannot be underestimated. This configuration also brings more benefits to future equipment expansion and renovation.
Automation functions include functions in each section of the hot strip rolling line starting from the slab transport rollers and ending with the coil transport to ensure that all work is carried out in a correct and coordinated manner.
The Southwest Stainless 1450 hot rolling production line automation system uses the SIEMENS PLC+TDC configuration solution.
The Southwest Stainless 1450 hot rolling production line automation system is divided into process control level (L2 level), basic automation level (L1 level) and transmission level (L0 level) vertically, and is divided into heating furnace area, rough rolling area and finishing rolling area horizontally. , four areas of take-up area.
At the process control level and basic automation level of hot rolling, a subnet is set up in each area to connect the process machines, HMI servers, PLC and other control equipment in this area, so that PLCs in the same area can quickly exchange data. Process machines and HMI servers can also easily exchange data with the PLC in this area. The process machines and their terminals, HMI servers and HMI equipment in each area are interconnected through the backbone network to form a complete whole. Through the backbone network, process machines in each region and process control-level terminal equipment can exchange data with each other. Process machines and HMI servers in each region can also exchange data with each other. At the same time, basic automation-level HMI equipment can also communicate with HMIs in this region. Servers exchange information.
2) Network system
The network equipment of Southwest Stainless Steel Hot Rolling Automation Control System adopts extremely reliable industrial Ethernet products. Specifically, the system uses switches with high-speed redundant ring functions to build four 100M redundant ring Ethernet networks in the heating furnace area, rough rolling area, finishing rolling area and coiling area where control equipment is relatively concentrated. These switches are distributed in Operation rooms and main electrical rooms in each area. At the same time, a high-performance Ethernet switch is used as the main switch and placed in the process computer room. The secondary switch located in the computer room uses twisted pairs to connect to the main switch, while the secondary switch located in the dispatch room and the four regional ring networks need to be connected to the main switch through optical fibres due to long distances or poor wiring environments. The speed of these connections Both are 100M. In this way, the network system becomes a unified whole.
Network systems use the TCP/IP protocol. The process machines are placed in the computer room and directly connected to the main switch. They are equipped with two network cards, one for connecting to the main network and the other for connecting to the corresponding regional subnet. The HMI server is placed in the regional operation room and connected to the switch in the operation room. They are also configured with two network cards, one for the backbone network and the other for the corresponding regional subnet. HMIs and network printers distributed throughout the system can be connected to any switch nearby, and they are all connected to the backbone network. Since most basic automation-level HMIs and the HMI servers they need to access frequently are on the same switch, this internal data exchange will not increase the burden on the backbone network. The PLC placed in the main power room of each area connects the groups to the switch in the main power room. The width gauge, thickness gauge, crown gauge (reserved) and flatness gauge (reserved) located at the exit of the finishing rolling mill will be directly connected to the Ethernet in the finishing rolling area, and the instrumentation and automation control system will be implemented through the TCP/IP protocol. data exchange between. The connections between the above-mentioned network terminal equipment and switches all use twisted pairs, with a rate of 100M.
For the two areas of finishing rolling and coiling, which are closely related to each other, have a large amount of data exchange, and have very strict real-time requirements, the system uses a GDM network with a communication speed of up to 640Mb/s to connect related PLCs. In addition, the 12M Profibus-DP bus can be used to realize the mutual communication between the PLCs in the three areas of rough rolling, finishing rolling and coiling.
3) Other parts
The process control level uses 5 high-performance servers as process machines. Three of them are used for process monitoring of rough rolling, finishing rolling/coiling, and laminar cooling, one is used as a data center processor, and the other is a backup machine that is also used for application development. The operating systems of the five process machines all use Windows 2003 Server, and the database uses Oracle 9i.
The human-computer interaction devices used in this system include L2 terminals, HMI servers, HMI clients (HMI for short) and printers. The process control level (L2 level) terminal uses P4 microcomputers, a total of 7 units, all placed in the process computer room. The system is equipped with an HMI server in each area, which is installed in the rough rolling operating room, finishing rolling operating room and coiling operating room respectively.
In the entire automation control system, a total of 9 sets of Siemens SIMATIC TDC and 6 sets of S7-400 PLC are used on the main rolling line. These control systems, including the transmission system on the rolling line and the human-machine interface WinCC, are both Siemens products. Therefore, the network connection of Ethernet, Profibus-DP network, and MPI network has the characteristics of relatively simple communication and easy maintenance. PLC equipment in each area is installed in the main electrical room of this area.