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“If the grid goes into a blackout state, the PV system cannot help.
So if used in this way, PV solar and wind generation can never be a
substitute for base-load generation because they cannot replace the
loss of grid power,” he explains.
ABB’s microgrids, however, are grid forming. “While they will syn-
chronise to a grid if it is available, they can also provide the references
for renewable and fossil energy generation to follow. PowerStore
sits between the grid and all the other generation sources, so PV,
diesel and wind generation will all look to the PowerStore reference
in order to synchronise.
“So while microgrids can be grid connected, as we see at our
demonstration plant here in Longmeadow, they are also 100%
‘islandable’. Here, we have grid-connected power, PV
solar generation, the battery and diesel generation all
interconnected via a common ring and automatically
managed by the Microgrid Plus Distributed Control
System (DCS). The unique feature of ABB’s microgrid
control system is that it has a distributed network of
controllers allowing for redundancy, expandability and
maintenance to take place without interrupting genera-
tion of power.
“As soon as an outage is detected, the PowerStore
provides the reference for the off-grid generation. Then,
when as the grid comes back on line, the PowerStore
resynchronises, which will cause the off-grid generation
sources to follow. The grid can then be safely brought
back into the supply mix,” he adds.
Key features of microgrids
The core purpose of ABB’s microgrid solutions is power security and
grid resilience. Since no single generation option is able to offer this
all of the time, it makes sense to combine power generation sources
to make sure power is always available. “While seamless power
changeover is not always necessary, it is now a primary part of our
offering and is often essential,” Duarte suggests.
“Probably the largest microgrid market is in the USA, where you
would think they have no need of it. Why? Because of the increas-
ing occurrence of natural disasters, which tend to take out the grid
and cripple the affected community. To minimise the impact of such
events, the power needs to be restored immediately and microgrids
are being installed on a redundancy basis to back up the grid in
high-risk areas. Typically these are large systems of between 10 to
100 MW, but there is no capacity limit since the technology involves
the management and coordination of generation, not the generation
itself,” he informs MechTech.
A second objective is to achieve the lowest possible levelised
cost of energy (LCOE) from a combination of generation sources.
“Levelised cost of energy is a stream of equal payments, normalised
over expected energy production, that would allow a project owner
to recover all costs – including financing and an assumed return on
investment over a predetermined financial life – and expressing this
total as a tariff per kWh of generation,” he explains, adding, “this is
generally calculated for a 20-year life.”
With this information, ABB’s Microgrid Plus DCS is able to opti-
mally combine available generation sources to meet prevailing load
demand at the lowest possible cost.
ENERGY + ENVIROFICIENCY:
CARBON TAX
ENERGY + ENVIROFICIENCY
I n C o n v e r s a t i o n W i t h
The dc power generated from the panels is passed
through a single PVS 800 630 kW ABB inverter to
generate the ac supply.
take note
An infographic outlining the key fea-
tures of ABB’s microgrid installation
at Longmeadow.
• Microgrids are networks of smaller independent but inter-
connected generation ‘islands’.
• Gas, hydro, diesel HFO, solar, wind or geothermal sources
can be incorporated into the microgrid solution.
• The core purpose of microgrids is to manage and combine
the available power to best meet demand.
41
August ‘16
Electricity+Control