PV Penetration on Island Mini-Grid or Grid!- Niue. King Island Connect 2015

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

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3 The Pacific Ocean The Pacific Ocean covers: 32.4 % of the Earth s total area % of the total surface area of all of Earth s water Earth s total landmass is only % of the Pacific Ocean.

4 Population-Over 22 countries 4

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

6 Example of PV Penetration in Pacific Tokelau: country powered by three Hybrid systemswith 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

7 Example of PV Penetration in Pacific- Continued 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

8 Niue

9 Statistics Population approx Generation : 4 x 508kW generators Evening peak approx. 580kW Daytime kW 8.2 to 10 MWh per day

10 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)

11 PV Systems 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

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

13 Kema Dynamic Stability Study- Recommendations 1 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.

14 Kema Dynamic Stability Study- Recommendations 2 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 sec period from 0.65 to 0.50 pu. All existing and future inverters should use these settings.

15 Issue with crusher 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.

16 Intermittent Solar Output

17 Warren Crowley s Masters Study 2013 Homer Simulations 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.

18 Status: May 2014 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

19 GSES Recommendations at the time 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.

20 Current situation

21 THANK YOU Geoff Stapleton Global Sustainable Energy Solutions Pty Ltd p f m gses@bigpond.com