CaseStudy

Baoshan Iron & Steel Co., Ltd. (Baosteel for

short) is the largest and most modernized

iron and steel complex in China. Baosteel has

established its status as a world grade steel

producer with comprehensive advantages in

reputation, talents, innovation, management

and technology. According to “Guide to the

World Steel Industry”, Baosteel is ranked

among the top three most competitive steel

producers globally. Baosteel is also believed to

have the most potential for an iron and steel

enterprise in the future.

The company specializes in producing high-

tech and high-value-added steel products.

Meanwhile, it has become the main steel

supplier to industries of automobile, household

appliances, container, oil and natural gas,

exploration and pressure vessel. Baosteel

exports its products to over forty countries

and regions including Japan, South Korea

and countries in Europe and America. (http:

//www.baosteel.com/plc/english/indexe.htm)

2050 Hot Mill Plant of Shanghai Baosteel

Group Ltd. has four step heating furnaces

processing 5 million tons of slab heating per

year. Citect provided the energy control system

in this plant.

SERVER REDUNDANCY

Under normal conditions, the primary

I/O Server is responsible for all data

communication with the MODCELL control

stations. At a regular time interval, the

secondary I/O Server checks whether the

primary server’s communication connection

with the MODCELL is functioning as normal.

If the communication is not functioning

normally, the secondary server triggers the

hardware Alarm to inform maintenance

personnel of the problem. The secondary I/O

Baoshan Iron and SteelCitectSCADA’s Redundancy Ensures Stable and Consistent Communication for China’s Largest Steel Complex

Server also regularly checks the primary I/O

Server’s running status. If the primary server is

not functioning properly, the secondary server

automatically takes over the primary server’s

I/O functions. When the primary I/O Server

resumes its normal functionality, I/O control is

automatically passed back to it. Consequently,

under normal circumstances, the secondary

I/O Server does not store the MODCELL data,

which greatly reduces the communication

load on the MODBUS network. Through

the system’s specialist program, MODCELL

variables and parameters that experience

changes are automatically copied to the

secondary I/O Server, thereby ensuring the

data’s consistency and integrity.

COMMUNICATION PATH

REDUNDANCY

The primary I/O Server and the secondary I/O

Server are both connected to the MODCELL

control stations via completely separate

communication paths. If the primary server’s

connection to the MODBUS is blocked, the

secondary I/O Server will immediately start

communicating with the control station that

the primary server cannot communicate with.

The secondary server will continue to do this

until the primary server’s communication link is

restored.

Baosteel is ranked among the top three most competitive steel producers globally

Figure 1: The Tubebed at Baosteel

PRESERVING CONSISTENT DATA

In order to decentralize the workload of the system and ensure the system’s efficiency during the design of the hot-mill control system, Citect adopted I/O and other open control service principles. The primary I/O Server acts as the redundant Alarm, Report and Trend Server, whilst the secondary I/O Server is the primary Alarm, Report and Trend Server. Under normal running conditions, CitectSCADA operating stations only request Alarm, Report and Trend information from the secondary I/O Server. The internal system automatically carries out data replication between the two servers, hence preserving data consistency. Should the secondary I/O Server suffer a fault, all Report, Alarm and

Trend information requests are redirected

to the redundant Primary I/O Server. The

difference between this method and

communication redundancy is that even if

the secondary I/O Server returns to normal,

information requests from operating stations

will still be directed to the primary I/O Server,

unless the operating station is restarted, or

the primary I/O Server also suffers a fault.

This is done so that the system does not need

to continually check whether the primary

information server is functioning normally,

hence avoiding excessive system checks.

Baosteel is ranked among the top three most competitive steel producers globally

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Figure 2: The Rollmill at Baosteel