Geoff presents a comprehensive Pacific overview, selecting Niue as a PV integration case study. Geoff reminds the audience how often RE integration programs neglect the critical step of training and handover, with these processes critical to up skilling the region towards a sustainable engineering capability.

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Training • Consulting • Engineering • Publications
PV Penetration on Island Mini-Grid or Grid!- Niue
King Island Connect 2015
Geoff Stapleton

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The Pacific Ocean
• The Pacific Ocean
covers:
– 32.4 % of the
Earth’s total area
– 45.76 % of the total
surface area of all
of Earth’s water
• Earth’s total landmass is
only 90.13 % of the
Pacific Ocean.

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Population-Over 22 countries
4

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Many Grids in Pacific would be considered by some as ―micro-grids‖,
however for the Government and Utilities—this is there Grid.
What is a micro-grid?

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• Tokelau: country powered by three Hybrid systems-
with PV being main source of supply
• Tuvalu:
– 3 x 600kW generators- base load about 900kW—
– PV 500kW connected with SMA fuel saver plus
270kW
– Planning 1MW with storage
Example of PV Penetration in Pacific

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• Tonga
– Tongatapu - instantaneous penetration up to 45%
8.4MW peak demand and 3.5 to 4MW min demand
(Sunday mid afternoon when Solar is most effective)
– Vava'u - instantaneous penetration up to 65% 1.4 MW
peak demand and 700 kW demand during day
• Samoa—
– Peak Demand 20MW
– PV 6MW and more planned
Example of PV Penetration in Pacific-
Continued

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Niue

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Statistics
• Population approx. 1400
• Generation : 4 x 508kW
generators
• Evening peak approx. 580kW
• Daytime 400-500kW
• 8.2 to 10 MWh per day

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Distribution and Generation Operation and
overview
• Two Feeders
• There is a capacitive effect on the two feeders such that shunt reactors
were installed across the distribution system conductors and perform a
variety of functions including power factor compensation, network voltage
regulation and assist with the management of power system
disturbances.
• Operation :
– 1 generator at low peak and 2 generators during evening peak, but 2
required when rock crusher (50kW) turned on. Also both turned on as a
safety reason for the crane at wharf (11kW).
– 2nd unit typically started when first generator is 75% loaded (380k)

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• Niue High School 24kW
(2009)
• Hospital 30.6kW (2009)
• Power Station -200kW
with 158kWh battery
storage (200kVA Inverter)
(Feb 2014)
• Airport 92kW (May 2014)
• 1.7kW NPC Office
TOTAL 348kW
PV Systems

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• EasyPower model
• 384kW of solar and 180kW of batteries
Kema Dynamic Stability Study-Sep 2012

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• There must always be at least one diesel generator operating to provide
the system frequency and voltage signals used by the solar power plants.
This means that the island cannot rely on 100% solar generation at any
time during the day.
• The maximum amount of solar (renewable) generation is limited by the
minimum load on the diesel generators (about 80 kW).
• With a typical peak load of 480 kW, the maximum solar generation would
be 400 kW.
• The planned solar generation (384 kW) will be very close to this maximum
limit.
•
Kema Dynamic Stability Study-
Recommendations 1

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• Based on a sample of solar output during January 2012, solar generation
on Niue should produce less than 5% of Niue annual energy (fuel).
• All the prospective (future) cases showed that one diesel should handle
normal renewable output variations.
• The inverters used with solar generation are susceptible to low-voltage
drop-out during certain extreme events; the voltage ride-through for the
inverters should reduce the low voltage set point for the 0.20-2.0 sec
period from 0.65 to 0.50 pu. All existing and future inverters should use
these settings.
Kema Dynamic Stability Study-
Recommendations 2

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• KEMA noted during their stability
study that when the crusher started
that the inverters tripped out caused
by frequency fluctuations.
• This was also observed by Mr.
Crowley while undertaking his
masters study.
• The battery storage with the 200kW
airport system was installed to help
maintain frequency stability when the
crusher started.
• However it emphasizes why the
frequency windows need to widened
to allow a minimum down to 45hz.
Issue with crusher

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Intermittent Solar Output

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From his simulations, Warren recommended the following additional
equipment :
• 200kW Solar PV.
• 300kW By-directional Inverter charger system.
• 1472kWh Battery System.
• Control Unit.
This option provides diesel savings of between 6.74% and 9.45% and cost
savings of between 12.93% and 19.44% relative to the Power system. The
variations in savings are dependent on the fuel price and island load at the
time.
Warren Crowley’s Masters Study 2013
Homer Simulations

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• In May 2014, feeder
with no solar had a fault;
this led to generator
being under loaded
because of the solar;
and it turned off -
complete Island
blackout!
• Some of the solar then
switched off to prevent it
happening again
Status: May 2014

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• Monitoring and data logging systems are installed, including monitoring of
power quality not just energy.
• A study should be undertaken that determines the size of PV array and
energy storage required for Niue to achieve 100% solar target, and then
outline how this should be achieved in manageable stages. This would
also require a study of the utility tariffs to keep NPC viable.
• The recommended study should also provide the size of the storage
immediately required in order to meet the current stability issue, but the
size as recommended in Mr Crawley’s report would be sufficient. Further
study is required on what the recommended inverter/battery solution
should be.
GSES’ Recommendations at the time

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Current situation

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THANK YOU
Geoff Stapleton
Global Sustainable Energy Solutions Pty Ltd
p 1300 265 525| f +61 2 9024 5316 | m +61 418 429 255
gses@bigpond.com| www.gses.com.au