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17
CONSTRUCTION WORLD
SEPTEMBER
2017
ENVIRONMENT & SUSTAINABILITY
“The mobile transformer will do two things, firstly, it will provide a
temporary supply to the project, to mitigate the risk that Eskom
transmission is delayed with energisation of Helios. Secondly, it will
allow for early grid code testing of Loeriesfontein Wind Farm, which
will ultimately increase the chances of early operations, ahead of the
Commercial Operations Date.
“We have worked very closely with Eskom to supply and operate
the mobile transformer, which is typically used by the Utility
to temporarily connect to substations during maintenance or
unplanned shutdowns to allow continued use of substations. Mobile
transformers are not normally used to connect Wind Farms to the
distribution system,” explained Kevin Foster, Country Construction
Manager for Mainstream Renewable Power.
The Helios substation energisation is on track for 15 August
2017, at which point the Loeriesfontein Wind Farm will be able
to commence with final grid code testing prior to commercial
operations. CONCO is responsible for the electrical component of the
balance of plant works, including the engineering, procurement and
construction of the medium voltage collector system, substation,
overhead line connection and the temporary transformer.
How the transformer fits into the plant
Each wind turbine is connected to a step-up transformer which
boosts the generating output of the wind turbine generator from
690 V to 33 kV. These transformers are located at the base of the
wind turbine. From here the cables throughout the wind farm
bring the 33 kV current from the step up transformers to convene
at the substation where the main transformer is situated. The
main transformer at the substation increases the voltage further
from 33 kV to 132 kV – the voltage required to transfer the
power to Eskom.
The Loeriesfontein and Khobab Wind Farms are part of
the South African Government’s Round 3 Renewable Energy
Independent Power Producer Procurement Programme (REIPPP)
and are managed both in terms of construction and operations by
Mainstream Renewable Power South Africa. The Loeriesfontein
and Khobab Wind Farms, are expected to be operational by
December 2017.
LWF connects mobile transformer
Loeriesfontein Wind Farm, in the Northern Cape, has been
making use of a mobile transformer to allow for an early
connection to the grid for commissioning of the turbines,
prior to the energisation of the Helios substation, which is
the permanent grid connection.