Ips connect 2015 geoff stapleton

creating sustainable change through education, communication and leadership © 2014 GSES P/L Training • Consulting • Engineering • Publications

PV Penetration on Island Mini-Grid or Grid!- Niue

King Island Connect 2015

Geoff Stapleton


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.


Population-Over 22 countries

4


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?


• 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


• 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


Niue


Statistics

• Population approx. 1400

• Generation : 4 x 508kW

generators

• Evening peak approx. 580kW

• Daytime 400-500kW

• 8.2 to 10 MWh per day


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)


• 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


• EasyPower model

• 384kW of solar and 180kW of batteries

Kema Dynamic Stability Study-Sep 2012


• 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


• 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


• 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


Intermittent Solar Output


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


• 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


• 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


Current situation

creating sustainable change through education, communication and leadership © 2014 GSES P/L

THANK YOU

Geoff Stapleton Global Sustainable Energy Solutions Pty Ltd p 1300 265 525| f +61 2 9024 5316 | m +61 418 429 255 [email protected]| www.gses.com.au

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http://www.gses.com.au/

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Ips connect 2015 geoff stapleton

Engineering

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