MRO
Original turbine manufacturer ABB
is no longer involved in ongoing support
the upgrade of the four turbine PLC’s.
Phase 3 will upgrade the remaining nonturbine
control system PLCs, for station
equipment often referred to as balance
of plant. That includes monitoring of
the ancillary systems associated with
the super grid transformers, hydraulic
control of the control gates at the dam
and other balance-of-plant equipment.
BENEFITS
“The bene ts of the upgrade include
long-term, fully-supported hardware
and software from the OEM, improved
interface and communication
between systems, and introduction of
redundancy within the control systems,”
says MacFarlane.
“The bene ts
of the upgrade
include fullysupported
The station provides
electrical power
through unitised and
common electrical
distribution systems
(high voltage and
low voltage), including
various transformers. Paul
Deacon, principal systems
engineer at ITI, explains that
the existing control system is based
around unitised and balance-of-plant
PLCs on a dual Fieldbus network, with
communication to a main/standby
SCADA system via two alarm PLCs and
a station PLC.
Deacon describes the new system as
hardware
being based
around a
redundant
PLC
architecture
to replace
the existing
(and obsolete)
sequence-control
and temperaturemonitoring
PLCs. The majority
and software,
communication
between systems
and introduction of
redundancy”
of alarms are hard-wired to the
separate station and alarm system.
Redundant ethernet communications
are provided between the unit and
alarm & station PLCs. A main/standby
SCADA system provides the interface
to the control room. A fibre-optic
wide area network connects these
systems to the Lanark and Galloway
Hydro schemes.
Upgrades have been scheduled
during annual maintenance outages.
Deacon says that the entire process
was organised in phases. “The
previous alarm and station system
upgrade included additional design,
hardware and planning to ensure
the existing interfaces between
the unit, balance of plant systems
and SCADA systems remain intact.
Each unit refurbishment can then
be installed with only limited
software modifications required for
re-routing of alarm & status data,
ensuring the integrity of all plant
data,” says Deacon.
48 www.operationsengineer.org.uk Winter 2021
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