9.Advanced open control system applied to the rolling mill plant

A dvanced open control system applied to the rolling mill plantAkira Nojima, Kahchoon Siau , Hideho Goudo, Akihiro Kashiwamura 1,Weiming ZHOU, Kai XIE 21. ABSTRACTIt is requested for control system of rolling mill to manage a large number of process data and precise and fast control. In addition the system shall have high reliability and easy maintainability. For above reasons, manufacturer propriety system has been introduced for a long time, however, rapid progresses of PC and information technology provide open environments to the control system, that is beneficial to the users in addition.The advanced open control system utilizing this progress is applied to the Hot Rolling Mill Plant of Hunan Valin Liangang Steel Co. Ltd., which is most sophisticated and largest in size in the rolling mill area. This paper describes the features of advanced open control system and the achieved results of actual application based on the above plant.LAN is the key component of the control system. In this system, two kinds of LAN are applied. One is the control LAN (industrial high speed LAN). The other is the information LAN (standard Ethernet). All the system components such as process computers (Level 2), Level 1 controllers, motor drive etc. are connected to above LANs and exchange information each other.2. INTRODUCTIONThe contract for the project was awarded in January 2002, and main equipment was delivered at the end of August 2003. Installation and individual tests were carried out on site, and the first coil hot run test was successful at the end of December 2003. The period required for production of the first coil was only 23 months from the contract, which is the shortest time for a hot rolling mill in China. The first cast from No.1 strand was in February 2004, and the first cast from No.2 strand was June in 2004. The production exceeded 1.2million ton at 2004. Toshiba Mitsubishi -Electric Industrial Systems Corporation (hereinafter TMEIC) has supplied the advanced open control system with Main Motor, Drive System, Level-1 Automation System and Level-2 model setup system for this hot rolling mill plant for the stable production and the high quality products.3. PLANT SUMMARYThe production capacity of the plant is summarized in Table 1 shown below.Table 1 Production capacityItem SpecificationAnnual production (ton/year) 2.4 millionSlab thickness (mm) 55 ~ 70Slab width (mm) 900 ~1600Strip thickness (mm) 0.8 ~ 12.7Strip width (mm) 900 ~1600Coil maximum weight (ton) 29.6The configuration of mechanical equipment is shown in Figure 1. A Germany maker supplied the mechanical equipment and a USA maker supplied the tunnel furnace.1Toshiba Mitsubishi-Electric Industrial Systems Corporation2 Hunan Valin Liangang Steel Sheet Co., LtdThis plant is located in Hunan province of China. The maximum capacity of equipment is 2,400,000 Ton/year. There are two continuous castings and two 267m tunnel furnaces and 7 stands rolling mill equipment.Figure 1 Plant LayoutThis plant has two kinds of hot rolling process. One is batch-rolling process and the other is semi-endless-rolling process.(a) The batch-rolling process:In this process the thin slab from continuous caster is divided by the pendulum shear and transferred to the tunnel furnace. After the thin slab heated up to 1150deg C, the thin slab is discharged from tunnel furnace to 7 stands rolling mill to product a hot thin coil (min. 1.0mm).(b) The semi-endless-rolling process:In this process the long thin slab (max. 269m) discharged from continuous caster, passes through the tunnel furnace and is directly charged to 7 stands rolling mill to produce several hot thin coils (min.0.8mm). The strip is divided by high speed shear near to down coiler equipment.Table2 shows the main mechanical equipment specification in this rolling mill.Table 2 Main equipment specificationsItem SpecificationFinishing Mill 7 Stands 4Hi rolling mill7 Stands 10000kW motor7 Stands hydraulic screw down7 Stands bender7 Stands WR shifting6 Hydraulic type LoopersLaminar Cooling 8 banksHigh Speed Shear Motor driven Drum type shearDown Coiler 1350kW Mandrel motor3 Wrapper rolls with step control4. DRIVE EQUIPMENTTMEIC has two kinds of drive system for a large capacity (12 MVA) high-efficiency three- level inverter. One is GCT (Gate Commutated Turn-off thyristor) and the other is IEGT (Injection Enhanced Gate Transistor). For this plant, IEGT applied to the entire main drives of finishing mill. This system received the prize of 2002FY JMF Award for Energy-Conserving Machinery and has the following features: high efficiency, space saving, small higher harmonics and so on. All of AC auxiliary motors used IGBT (Insulated Gate Bipolar Transistor) inverter type AC drives system for whole rolling mill plant and rollertable. All drive systems are directly connected to Level-1 PLC control system by TOSLINE-S20 field bus.Table3 shows the capacity of main motors.Table 3 Main motor and drive panel capacityF1 10000kW-150/440rpm 16MVA Frame IEGT Drives F2 10000kW-150/440rpm 16MVA Frame IEGT Drives F3 10000kW-150/440rpm 16MVA Frame IEGT Drives F4 10000kW-150/440rpm 16MVA Frame IEGT Drives F5 10000kW-250/710rpm 16MVA Frame IEGT Drives F6 10000kW-250/710rpm 16MVA Frame IEGT Drives F7 10000kW-250/710rpm 16MVA Frame IEGT Drives5. CONTROL SYSTEMSFigure 2 shows the control system configuration of this plant.LAN consists of the control LAN (TC-net100) and the information LAN (100M based Ethernet). All system components including process computers (Level 2), Level 1 controllers, motor drives etc. are connected to TC-net100 and exchange information each other in real time. The 100M base Ethernet is applied to information LAN to connect human machine interface (HMI), Level1 controller engineering tool and other third party systems.CONTROL LAN (TC-NET100)Control LAN (TC-net100) has two kinds of transmission function. One is scan data transmission (cyclic broadcast) function and the other is TCP/IP, UDP/IP message data transmission function.The control LAN (TC-net100) has the time critical function by using 128kW common (shared) memory in order to satisfy the high speed data transmission required by the process control. 100M based Ethernet is applied to TC-net100 physical layer. All controllers and process computers are connected to TC-net100 to share the real time process data on TC-net100 common memory. TC-net100 realize seamless communication among each controllers.The TC-net100 has a deterministic media access control function called DOMA （Deterministic Ordered Multiple Access ）protocol in order to avoid collisions that occur when a number of the nodeFigure 2 The Control System Configuration Figure 2 Control System Configurationsend data frames simultaneously and to provide each node with the opportunity to send data in a sequential order and within a predetermined time period. Table4 shows TC-net100 Specification.Table 4 TC-net100 SpecificationFunction SpecificationTopology Star Number of station Max.254 node / system Transmission cable Optical Fiber CableTwisted pair cableTransmission distance Max. 2 km (between station) ( 8 km possible with special repeater) Communication service 1) Scan transmission (cyclic broadcast)2) TCP/IP, UDP/IPTransmission speed 100Mbps Cyclic transmission High speed 1 - 160 msMedium speed 10 - 1,000 ms Low speed 100 - 10,000 msCommon memory size 128Kwords (1word=16bits) Throughput 3.8Mwords/sec (100Mbps, 32nodes, 1km) Redundancy Send/Receive circuit, Transmission cable Application PLC <-> PLC, PLC <-> Remote IO, PLC <-> PCTC-Net100 scan transmission (cyclic broadcast) consists of three kinds of scan speed level, High speed, Medium speed and Low speed. In this plant, the transmission speed is set as the high speed in 2ms, middle speed in 10ms, low speed in 1000ms.Figure3 shows TC-net100 Transmission Protocol Configuration. Physical layer is 100M based Ethernet. DOMA protocol is implemented as ASIC and controls scan data transmission and TCP/UDP IP data transmission without collisions.Figure4 shows the concept of scan transmission with common memory. TC-net100 has 128Kw common memory divided into 2048 blocks. The blocks are assigned to each node as talker blocks. The “TOKEN” which is the right to send data is rounded between nodes. When Node n receives the “TOKEN”, Node n sends data to all other nodes. After the “TOKEN” is rounded through all nodes, all nodes’ common memory data are synchronized.Figure5 shows DOMA transmission control. Transmission priority control consists of four levels. High speed scan data transmission has the highest priority. Middle speed scan data transmission has the second priority. Message (TCP/UDP) data transmission has the third priority. Low speed scan data transmission has the lowest priority. If the transmission load becomes more than TC-net100 performance, the lower priority transmission is delayed. When High speed scan time is set to 2msec, all nodes common memory data assigned for High speed scan transmission are synchronized within 2msec.-TCP/IP,UDP/IP message data transmission-Common (shared) memory based scan data transmissionRedundant NetworkEthernet-PHYDOMATCP/UDPIPCommon memoryEthernet-PHYFigure 3 TC-net100 TransmissionProtocol ConfigurationFigure 4 Concept of scan transmission with common memoryNode 1Common Node 2Common Node 3Common Node n CommonFigure6 shows the TC-net100 Node Detail screen of the engineering tool. TC-net100 actual data transmission speed for the high speed scan data of this project is 1260000nsec(=1.26msec). TC-net100 always sends data with its maximum performance. So, TC-net100 performance has enough margins for this project because high speed scan time is set to 2msec for this project.TC-net100 is applied to one of IEC61784-2 Real Time Ethernet international standard.CONTROLLERLevel-1 sequence controllers (S3), stand controller (STC) and remote I/O stations are connected to the control LAN. S3 and STC comply fully with IEC61131-3. The number of controllers and control cycle are optimized according to the process requirements. Software is implemented based on object-oriented configuration such as function block diagrams and local/global variables concept.Stand controller (STC) is applied to fast speed required hydraulic cylinder position control system. By this controller, it is available to set to 1.5ms scan time even if the application program is designed by using IEC61131-3 language.Table 5 Controller SpecificationFunction SpecificationProgramming Language IEC61131-3 (LD,SFC,FBD,ST) High Speed Control Bit 40ns, Floating point 200ns Scalability Same architecture for Small System(Single Stand Mill) to LargeSystem(Hot Strip Rolling Mill)Integration of Control Sequence Control (S3)/Loop Control (L3)/Computer Control (C3) Communication service 1) Scan transmission (cyclic broadcast)2) TCP/IP, UDP/IPOpen Network Ethernet (10/100Mbps), DeviceNet, PROFIBUS Standard UL, CEE NGINEERING TOOLClient / server concept is applied to the engineering tool (Figure7). One server tool manages all controllers’ software including STC and TC-net100 common memory data. The client tools are connected to the server using Ethernet. 10 client tools were connected to the server for this project in commissioning stage. By this client / server configuration, several engineers can carry on their work with cooperation through design stage, factory test stage and site commissioning stage. Maximum four tools can be connected to one controller with online. One tool can modify and monitor for any controller in the system. Online software modification is available.Figure8 shows program editor screen of this engineering tool. LD program, FBD program and SFC program are called three graphical language of IEC61131.3. The program circuit using these threeFigure 6 TC-net100 Node DetailFigure 5 DOMA transmission controlgraphical languages can be integrated on one program editor screen. Instruction execution order is from top to bottom and left to right. Instruction execution order can be displayed on program editor screen.Cross reference jump function is available between controllers connected by TC-net100 common memory because engineering tool manages TC-net100 common memory allocation and read / write information for each data.HMIHMI and controllers are connected by Ethernet. SCADA package software is used as HMI system. Engineering tool screen can be displayed on HMI screen. Engineering tool has the function to display the faulted module graphically. When some fault occurs in the system, the user can find the faulted module by displaying the engineering tool window on HMI screen (Figure9). This function is useful for operators and maintenance engineers to makes MTTR short.Permissive Condition Automatic Display FunctionWhen some permissive condition becomes faulted and the equipment stops, permissive condition display function is necessary in the control system. HMI graphic screens are designed for this purpose conventionally. If some permissive conditions are changed, usually controller software and HMI graphic screens are modified synchronously. Such kind of modification work makes not only total system maintenance cost up but also make mistake and generate inconsistency between controllerFigure 7 Engineering tool Client/server configuration Figure 8 Program editor screen Figure 9 Engineering tool screen on HMIFigure 10 Permissive Condition AutomaticDisplay Functionsoftware and HMI graphic screen information. We have developed Permissive Automatic Display Function in order to avoid such an unnecessary work, cost, mistake and inconsistency between controller software and HMI graphic screen information.This function doesn’t require to design any HMI screen. This function displays only faulted conditions as a ladder circuit automatically when some conditions becomes faulted in the permissive diagnostic circuit. If some conditions are generated by another circuit, they are backtracked automatically and reconstructed as one ladder circuit. Figure10 shows permissive condition automatic display function. “PR_up_pmsv” is permissive condition for Pinch Roll and consists of three ladder circuits. “Up_Limt_sw” becomes faulted first and then “SG_open_LS” becomes faulted, two faulted conditions are displayed on the permissive live screen. The first faulted condition is displayed on the permissive first faulted screen.FULL REMOTE I/O SYSTEMControllers’ all input equipments (i.e. sensors/switches) and output equipments (i.e. actuators / indicators) are connected to TC-net100 remote I/O stations and allocated to TC-net100 common memory. Controller software and remote I/O signals are connected by TC-net100 common memory. Centralized engineering tool server manages TC-net100 common memory allocation and the Level-1 controllers software (Figure 7). Client / server configuration provides optimum engineeringenvironment. It has various diagnostic functions, which are very useful for trouble shooting by users. Full remote I/O configuration is applied to this plant.ODG (Online Data Gathering)The unique feature of data acquisition system, Online Data Gathering (ODG) is applied to this plant. ODG system consists of client / server configuration. ODG server is connected to TC-net100. All plant input and output signals (more than 20,000 signals) are allocated on TC-net100 common memory and are being refreshed in real time. ODG system can collect any data from TC-net100 common memory and record them into the hard disk.This system has real time trend (minimum sampling time :1ms) display to show live data display during collecting. Setting the trigger signals / starting and stopping trigger are available for analysis and troubleshooting. And it is possible to save the graph and data during displaying real time trend graph like camera (snap shot function).Figure11 shows ODG system configuration. Maximum 10 clients can be connected to ODG server through Ethernet. TC-net100 common memory data can be imported from engineering tool to ODG. Drag & drop operation from engineering tool to ODG is also available. Figure12 shows ODG trend graph display of this plant.ODG Client PCODG Client PC ODG Client PC ODG Client PC Figure 12 ODG Trend Graph Display Figure 11 ODG System ConfigurationRemote Maintenance ServiceRemote maintenance function that connects the customers’ site and the manufactures factory can be easily applied by using Internet communication based on HTTP Tunnelling technology. This function has already been developed by TMEIC and it is going to be applied to this plant soon.This technology does not require any special equipment in customers’ site. Just installing this function into PC and connect to customers’ factory LAN.Based on HTTP Tunnelling technology- No special equipment in customer siteFigure 13 HTTP Tunnelling Technology basedRemote Maintenance System6. CONCLUSIONThis paper introduces an advanced open control system applied to Hunan Valin Liangang Steel Co. Ltd. thin slab hot strip mill plant started on the end of 2003. It takes 11months to produce 1.2million tons after the 1st Coil. This is the shortest recode in China.The Semi-endless rolling was successfully done to roll 269m long thin slab, and the new record of the length of the thin slab in China was established. In addition, 0.8mm ultra thin strip was achieved in the semi-endless rolling process technology.The efficient TC-Net100 feature network configuration is a critical factor in organizing a high performance distributed control system for the rolling mill plant.7. REFERENCES[1] M. Iwase, A. Kashiwamura, K. Maruyama, K. Murata and H. Nagao, "Full-Scale Application of the IEC Based Control System to Mini Mill Plant, IEEJ, 2004 (Japanese)[2] A. Nojima and I. Kasahara, “The integrated controller system applied to the steel plants control system,” Toshiba review, 2000. (Japanese)[3] A. Nojima, H.Taruishi and O.Iwabuchi , “The integrated controller engineering tool” Toshiba review, 1999. (Japanese)[4] Y. Sashida, Y. Shiobara and I. Kasahara, “An Ethernet based time critical control network for industrial control systems,” ISA, 2001.[5] J. Hobbs, J. Burgers, H. Kojima, K. Honda and H. Imanari, “Hot strip mill accompanying Electric arc furnace for SSM(Thailand),” AISE Press, 2000.Note:“Ethernet” is a registered trademark of Xerox Corporation. The names in this paper may correspond to trademarks of related companies.“DeviceNet” is a registered trademark of ODVA (Open DeviceNet Vender Association. Inc). “PROFIBUS” is a registered trademark of PROFIBUS User Organization.“TC-net100”, “TOSLINE-S20” is a registered trademark of TOSHIBA Corporation.。