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The SCaDa system is connected to
the distributed control system (DCS) of
the new COGEN, which is a physical
expansion of the existing DCS system
operation and one gas to control and operate
turbine out of service) the already installed for the Package the power plant, general
SCADA system, based Boiler Project overview graphic displays
on the load shedding with main status, variables
procedure, will automatically and instantaneously and alarming of the turbine control systems are
adjust the power balance by tripping the chlorine repeated also at the DCS.
rectifers (i.e. the “interruptible” loads) and by The DCS also includes the monitoring function
securing the critical motor load’s power supply for the COGEN distribution system through the
on the basis of the available power production use of fast Ethernet link (IEC 61850 protocol) and
provided by the automatic frequency control of the hardwired signals.
generating units which are still in operation. A comprehensive rearrangement of the existing
The SCADA system is connected to the distributed primary electrical distribution network of the
control system (DCS) of the new COGEN, which is chemical complex was required to allow the
a physical expansion of the existing DCS system integration of the new power plant: some of
already installed for the Package Boiler Project. the existing systems have been modifed and
The DCS is connected to the turbines’ PLCs upgraded and new busses have been installed,
control systems and Scada system by means of a in order to allow commissioning and start-up of
fast Ethernet link with OPC protocol, while critical the new generation units with minimal impact to
signals are hardwired. the existing chemical production plants. In other
Since the DCS workstations are the main interface words, Dow’s internal network can be temporarily

Fig. 2 – Single Line Diagram

Impiantistica Italiana - Novembre-Dicembre 2013 63