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Using Energy Storage to
Enable High-Penetration
Renewable-Diesel Hybrid
Power Systems
Jim McDowall
Australian Energy
Storage Conference Sydney – June 2, 2016
Remote microgrids
– Rural communities
• Loads from 10s of kilowatts to a few megawatts
• Strong diurnal and seasonal patterns
– Off-grid mines
• Loads up to 10s of megawatts
• Relatively constant
– Powering concerns
• Cost of diesel fuel (including transportation to remote locations)
• Noise and emissions
• Maintenance costs
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Adding renewables to microgrids
– Solar and/or wind can substitute for diesel power
• But without storage, diesels still have to supply spinning reserves
– Energy storage allows maximum contribution of
renewables
• Shut down diesels whenever possible
• Run diesels at high load for increased efficiency and reduced O&M
• Fuel savings can easily be 50% to 75% or more
3 High-Penetration Remote Hybrid Power Systems
PV-Diesel only
possible
PV-Diesel & small-sized
storage
PV-Diesel & large-sized
storage
How much PV and how much diesel ?
– Each site is different
• Load profile
• PV generation
• System constraints
• Environmental conditions
• Economic conditions
– Most systems optimum
in area of 40% to 150%
– Importance of simulation to
optimize component sizes
4 High-Penetration Remote Hybrid Power Systems
150%
Power generation cost
PV rating (% of load)
0% 50% 100% 200%
Saving potential
PV + Diesel System #1
Genset only
PV + Diesel System #2
Different optimum depending on different cases
Courtesy SMA
Simulations with HOMER Pro
5 High-Penetration Remote Hybrid Power Systems
– Extremely useful for quick check of
many component combinations
– No need to have detailed project
data
– Example
• Small Caribbean community
• 70 kW peak load, 25 kW average
• 100 kW of PV
• How big a battery?
HOMER Pro results
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30
35
40
45
50
0 2 4 6 8
PV
fra
ctio
n (
%)
Battery strings
Life = 9 years
Life = 18 years
Life = 20+ years
Detailed simulations with proprietary models
– Saft models in Matlab-Simulink
– Electrical, thermal & aging characteristics
– Same algorithms as battery
management systems
– Allow fine-tuning of operational
parameters for optimum results
– …but require more detailed data
for load and renewable output
7 High-Penetration Remote Hybrid Power Systems
Matlab-Simulink typical results
8 High-Penetration Remote Hybrid Power Systems
Other sizing considerations
– Ability to run diesels-off for village power
• Particularly during periods with high renewable output and low load
• Requires a grid-forming voltage-source converter
• Allows diesels to be baseloaded rather than load-following
– Less important for off-grid mines
• May be limited space for PV array to support full load
• Diesel operation may be required to support thermal loads
9 High-Penetration Remote Hybrid Power Systems
Case study – NTPC Colville Lake
– An electrical island! 50 km north of Arctic Circle
– 150 inhabitants
– 150 kW peak; 30 kW base load
– Diesel fuel delivery only by ice road
• Cost of generation ~$2.60 / kWh!
– New power station
• 2 x 100 kW diesels + 150 kW diesel
• 50 kW of solar in summer 2014
– expanded to 130 kW in 2015
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Project timeline
– Contract signed July 2014
– Saft Intensium Max 20M container 232 kWh with 240kW ABB PCS100
– Development of cold-weather package
• Insulation for –50°C
• Hydronic heating coil for glycol heating
– Delivery to Edmonton for integration
December 2014
– Ice-road transportation February 2015
– Installation / commissioning September 2015
– Started diesel-off operation January 2016
11 High-Penetration Remote Hybrid Power Systems
Next steps
– Test PV curtailment functionality
– Quantify fuel savings
– Optimize design for future village-
power installations
12 High-Penetration Remote Hybrid Power Systems
Case study – Kotzebue Electric
– KEA operates a wind-diesel hybrid power system
• Average load – 2500 kW; 3500 kW maximum
• 6 diesels – 725 kW to 3080 kW
• 19 wind turbines – 2940 kW total – 15 - 20% capacity factor
– The case for storage
• Reduce curtailment of existing wind turbines
• Fast frequency response for outage mitigation
• Reduce use of diesel peaking units
• Allow diesel-off operation
• Increase penetration of renewables
• Bottom line – reduce fuel cost
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High-Penetration Remote Hybrid Power Systems
About the energy storage system
– Saft Intensium Max+ 20M Li-ion battery
• 20-foot ISO container
• 950 kWh energy rating
• Up to 2000 kW of power
– ABB PCS100 power conversion system
• 1225 kW continuous power
• Grid-forming mode for diesel-off operation
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Action plan
– Controls to be implemented
• Economic dispatch for load leveling
• Fast frequency support during high wind / low diesel operation
• ‘Iso mode’ for diesel-off operation
• Black-start capability for diesel plant station power
– No firm results yet, but we expect energy storage to
provide major improvements to KEA grid operation
15 High-Penetration Remote Hybrid Power Systems
Case study – Cobija PV diesel hybrid power plant
– Pando province, northern Bolivia
• Amazonian rain forest
• Not connected to national grid
• 65% electricity coverage
– World’s largest PV-diesel hybrid
• 16 MW diesel generation – 8 MW max load
• 5 MW PV
• 2.2 MW Li-ion storage system (SMA, Saft)
• 50% of Cobija power needs (37 GWh/yr)
– Main stakeholders
• General contractor: Isotron SAU (Isastur Group))
• Owner: ENDE (Empresa Nacional de Electricidad)
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The storage solution
– 2.2 MW – 1.2 MWh
• 2 containers Intensium Max 20 M
• 4 Sunny Central Storage 630 – SMA
• compensation of PV fluctuations
– Fuel Save Controller – SMA
• Calculates maximum PV injection to grid
• Smooth operation of gensets
– Replaces 2 gensets running @50%
– Commissioned December 2014
– 2M liters annual fuel saving
17 High-Penetration Remote Hybrid Power Systems
Courtesy SMA
Conclusion
– Hybrid powering of remote microgrids is driven by increasing
competitiveness of renewables
• Potentially good business case
• Investors ask for high ROI, substantial savings / advantages
• Proven concepts & technologies preferred
– Storage allows high renewable penetration, and ensures operational
excellence
– System sizing & optimization are complex
• Specific to each case: close cooperation of developer and supplier
• Simulation capability is key!
• Need strong system control capability to manage multiple components and parameters
18 High-Penetration Remote Hybrid Power Systems
