MRO
The four turbines were
upgraded in 2005
Upgrading
Hollow Mountain
A Scottish power station is undergoing a programmable logic controller (PLC) upgrade that will see the station’s
current system replaced with a new design to improve Cruachan’s e ciency. In a three-year project, system
integrator ITI will undertake the design, installation and commissioning across the station’s four units
Drax Group’s Cruachan Power
Station, a hydroelectric
pumped storage plant built
inside the hollowed-out
mountain Ben Cruachan,
is undergoing a £1 million upgrade to
modernise its turbine control system.
Cruachan plays a critical role in
stabilising the country’s electricity
system due to its exibility. The plant
can generate power in less than a minute
when needed, and can also store excess
electricity from the grid like a giant
battery, a service which was called upon
during the lockdown when low electricity
demand coincided with periods of high
wind power in Scotland.
The plant’s reversible turbines pump
water from Loch Awe to an upper
reservoir on the mountainside to store
excess power from the grid. The stored
water is then released back through
the turbines to generate power quickly
By Will Dalrymple
and reliably when demand increases. In
July 2020, Cruachan became the rst
power station in Britain to provide critical
system support services to the National
Grid as part of an innovative stability
contract aimed at reducing the threat of
blackouts.
That six-year contract involves one
of the power station’s turbine units
providing support services such as
inertia to keep the electricity grid at the
right frequency, to enable more wind and
solar power to come online.
Drax says that inertia was traditionally
a by-product of the kinetic energy in the
spinning parts of large traditional power
stations. But as the country’s electricity
system has transitioned from traditional
sources of power like coal to renewables,
such as wind and solar, there has been
an increased need to separately procure
inertia to maintain stable, secure supplies
of power. Through the stability tender,
the grid has procured the equivalent
amount of inertia as would have been
provided by around ve coal- red power
stations.
Ian Kinnaird, Drax Group’s head of
hydro, said: “Cruachan plays a critical
role in supporting renewable energy in
Scotland and stabilising the electricity
grid. As the country continues to
decarbonise, the station’s exibility
has never been more important. This
upgrade will ensure the Hollow Mountain
can deliver the fast, exible power that
hundreds of thousands of homes and
businesses rely on for many decades to
come.”
OPERATION
Four Francis-type turbines are at the
heart of the station. Units 1 and 2 run
at 500rpm; units 3 and 4 at 600rpm.
Pumping water uphill, units 1 and 2
operate at 128MW and units 3 and 4 at
46 www.operationsengineer.org.uk Winter 2021
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