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Totally integrated automation system

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I S Systems (ISS) has supplied a totally integrated automation system to BlueScope Steel ’s new metal coating facility in Vietnam. The facility is located south-east of Ho Chi Minh City in the Phu My industrial area of Ba Ria Provence.

Kawasaki Heavy Industries (KHI) from Japan was engaged to design, supply and manufacture three steel strip process lines for the facility. These consist of a metal coating (Zincalume) line (MCL), coil paint line (CPL) and coil slitting line (CSL).

The new facility is part of BlueScope Steel’s planning and development in the region and the first major such facility in Vietnam. KHI chose ISS from a number of international competitors to be principal electrical engineering supplier. ISS was contracted to supply, design, manufacture and commission of strip transport systems for all three process lines.

The MCL has a production capacity of 125,000 tonnes per annum (tpa). It consists of a conventional twin pay-off reel entry section, coil cars, magnetic conveyors, fully automatic seam welder, bridles and horizontal accumulating tower. There is a strip cleaning section complete with sprays and brush scrubbers, while the NOF annealing furnace is a horizontal type with several heating/cooling stages.

The main coating system consists of a Zincalume main pot and pre-melt pot. An after-pot cooling section has been provided prior to the skin conditioning mill and tension leveller. A surface treatment section, consisting of four horizontal top and bottom coaters, has been supplied along with the exit section.

The CPL has a production capacity of 50,000 tpa. It consists of similar entry and exit sections to the MCL. The coating section consists of an S-Rap primary coater and cantanary oven, followed by additional coater.

The CSL is a conventional slitting line with an annual capacity of 15,000 tpa. It is capable of recoiling and slitting as well as cut to length.

Scope of supply

THE ISS scope of supply included:

• Design of automation and strip transport systems.

• Development of all automation and strip transport software.

• Design of SCADA systems, supply of networks and hardware.

• Development of associated electrical schematics to allow manufacture and installation.

• Supply of over 180 variable speed drives (4-400 kW) in cubicles.

• Supply of over 300 strip transport and process AC motors (some with gearheads, encoders, brakes and separate cooling).

• All control desks and control stations and associated controls.

• Supply of PLC systems in cubicles with a capacity of handling over 5000 I/O (points mostly distributed in the field).

• Design and supply of a line access system to allow operations to perform tasks safely.

• Supply of high speed data acquisition systems for line performance and diagnostic monitoring.

• Supply of PA systems and control power distribution systems.

Challenging time schedule

THE greenfield project had an ambitious 24 month schedule, from the date of the contract being awarded to plant start-up. The tight schedule meant that equipment deliveries commenced six months after receiving the contract and had to be completed 12 months into the project. Commissioning of the first process line (MCL) was scheduled to commence 18 months into the project.

ISS worked closely with its partners, including Siemens , to co-ordinate the logistics of sending equipment to over 10 countries including America, Japan and Korea. This equipment was further integrated and tested before being dispatched to Vietnam from these countries.

Logistics for transporting equipment manufactured in Australia was critical: over 100 meters of VSD cubicles had to be crated, packaged and delivered to the Phu My site.

To meet the tight schedule, ISS developed systems to manage the large amounts of information associated with the project. This allowed the designers to develop and reuse core information throughout the life of the project, and relate information across a number of parallel design activities. This system had to cope with changing user requirements, and was required to maintain a high level of integrity.

ISS worked closely with the client (KHI, Hatch and BSL) to fast-track the development of plant operation and functional specifications. This was a critical part of meeting the schedule and the success of the project.

Automation approach

ISS used its extensive experience of Siemens technology to develop an automation concept and control architecture specific to this project.

The structure of the basic automation system reflects the distributed fieldbus approach adopted by ISS. PLCs from the Simatic S7 family were used for the control of basic open loop strip transport and associated process control systems. The chosen fieldbus network was Profibus.

A large number of low density I/O (ET200S) modules were assembled into field control stations. This reduced the cost and time of site installation works and minimised the commissioning time on site. To maintain fast I/O scan times over the large physical system, the 5000+ I/Os were distributed over a number of separate Profibus networks.

The variable speed drives (VSD) were also integrated into the overall Profibus network. Individual Profibus networks were allocated to drive groups. Other devices on the network included local HMI displays, as well as third party devices such as encoders and controllers.

The main functions of the basic automation system were: process line sequencing and coordination; strip transport coordination and master referencing; speed, tension and position referencing; individual equipment operation; coil tracking and a strip tension profile model; coil data entry and setup; commutation and coordination with systems supplied by other vendors; auxiliary equipment operations (hydraulics, blowers, fans, pumps, etc.); and alarming and status information.

A fibre optic/copper network was installed for PLC to PLC communications and commutations to higher level plant systems.

Time is of the essence

TO meet critical process requirements, high speed controllers with program execution times of 1msec were utilised. Controllers from the Simadyn D family were used as part of the overall automation solution.

The high speed controller was associated with the close loop control of bridles with multiple rolls (master/slave), tension reels, accumulators, skin conditioning mill (SCM) and tension leveller (TL).

The main functions of these controllers were: strip elongation control, SCM position control, SCM rolling force control, motor torque control and load sharing, strip tension control, inertia compensation, roll bending force control, loss compensation and position control.

SCADA system

SIEMENS’ WinCC SCADA system was tightly integrated into the basic automation system.

The SCADA architecture consists of a central server (with future redundancy provision) and a number of clients. FAT clients were supplied for the main operator pulpits and Web clients in the field, with the additional ability to have Web clients anywhere for remote monitoring. The overall system consisted of over 10,000 tags and 12 WinCC nodes.

The SCADA system allows the line operators to perform all monitoring and control functions.

It includes provisions for process visualisation via graphical displays; indication of measured values; indication of plant status such as running/stopped; indication and handling of alarms and other messages; control functions such as starting/stopping of plant equipment and changing of setpoints; security systems; trending; and event time and date stamping.

Drive solution

A WELL designed drive solution was critical to the success of this project. A number of issues needed to be taken into account to correctly size and define the final drive architecture. These included speed ranges, torque/power ranges, heating/cooling, noise, isolation systems, drive groupings, physical installation conditions, cable types, mechanical brake capacity and encoder accuracy.

ISS selected Siemens Masterdrive inverters as the basis for the strip transport drive solution and design. Over 180 variable speed drives, ranging from 4-400 kW, were used.

The ISS design was based on grouping process drives into one drive section, each of which consisted of an infeed unit providing a 600 VDC bus for connecting the individual inverters.

The drive network communicates to the section PLCs via Profibus-DP (max. 12Mbaud). A high speed, fibre optic, peer-to-peer communication network between process drives allows for fast data transfer between and across drives.

For the critical strip transport drives, ISS selected motors from the Siemens 1PH7 range, with speed range and torque performance being paramount to line performance.

Siemens 1LA standard induction motors were selected for general process line purposes. Robust Flender gearheads from the Motex range were supplied. Motors and gearheads were assembled by Flender in Germany before shipment.

Simulation & testing

THE successful start-up of the plant and the minimum number of problems encountered during commissioning can be directly attributed to the extensive factory testing undertaken by ISS. All equipment manufactured and designed by ISS was rigorously tested prior to delivery to site.

This testing extended to control system software, as well as hardware.

The ISS design concept was to build an interactive process line simulation module into the code at the start of the project. A model of the process line and critical components was developed. During testing, this model was linked to the soon-to-be-commissioned process line PLC code via simulation interfaces.

This allowed ISS engineers to rigorously test the code prior to commencing work on site.

At the final stages of testing, the customer was invited to witness-test the control system. The interactive nature of the developed process model, coupled with the simulation interface, allowed the customer to operate the line in a virtual way.

From the SCADA system, the customer could run various line operation scenarios and confirm plant response.

Simultaneously, the actual control code was being tested for faults and robustness.

Testing provided the customer with the opportunity to gain a greater understanding of the system prior to its delivery. It also provided the customer with an opportunity to have greater input, prior to code going to site. A number of potential problems were thus avoided.

The overall ISS automation concept involved the integration of a dedicated third party (non-Siemens) high speed real time data acquisition system into the control system architecture. The high speed system captured plant variables on a common time base. The sequence of events could then be determined.

The data acquisition system greatly assisted in the successful commissioning and troubleshooting of the process, where high speed process interaction were numerous and difficult to split out. The system allows up to 2048 analogue plant variables to be scanned and monitored every 10msec or less.

Tools are available within the package to analyse the captured data in a number of useful ways.

Pleased with the results

PLANT commissioning commenced in 2005. After a cold run with the strip, the plant started production in late November 2005, on time and on budget. The start-up was very successful.

Over the next few months, the plant will ramp up to full capacity, and further enhancements made to the process. The electrical control system has bedded down quickly with minimal problems.

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