Moving Toward Hybrid Power Systems
Creating value with utility scale energy storage
ERCOT Renewable Technology Working Group
April 2009
Pioneers: Over a decade of energy storage projects have set the stage.
1994
2003
2007
2008
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What does it mean to be “hybrid”?
Hybrid Lessons
Better performance can be
achieved through faster response
and increased power capacity.
More efficient use of combustion
engine can be delivered through
steady throttling.
Ancillary functions of the vehicle,
such as braking, can be delivered
by using energy storage to recycle
energy.
Energy storage can be integrated into the electric grid to deliver a similar
set of benefits. The result will be a Hybrid Power System.
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Drivers: RPS goals creating a need for capacity and ancillary services.
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Different Services Would Require Different Type of Storage Device
Battery Options:
–Li-ion: quick charge/discharge, more efficient
–Flow (Zinc-Bromide): longer charge/discharge, smaller MW units,
more expensive
Potential Service Options:
–Ancillary Services markets
Regulation
Responsive Reserve
VAR support
Black Start
–Internal plant usage (auxiliary load, demand mitigation)
–Transmission constraints (intermittent renewable sources)
–Price arbitrage
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Li-ion Energy Storage for Ancillary Services System
Characteristics:
Self-contained 2MW modules with 15 min of run-time
Scalable by paralleling containers
90% round-trip efficiency
Faster response than any existing plant units
IEEE power quality standards
7-10 yr life
Less than 12 months to deploy
Portable
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Flow Energy Storage for Ancillary Services and Constrained
System Characteristics:
Self-contained 0.5MW modules with ~5 hours of run-time
Scalable by paralleling containers
70% round-trip efficiency
Faster response than any existing plant units
IEEE power quality standards
20 yr life
Less than 12 months to deploy
Portable
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Near-term Value in U.S.: ISO Ancillary Services Markets
Regulation is a near zero-energy service compensating for minute-to-minute
fluctuations in total system load and uncontrolled generation.
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Proof of Solution System: AES has built and interconnected a 2 MW
grid-scale battery energy storage system using Lithium Ion batteries.
This system was validated by KEMA Consulting for Ancillary Services
applications. The scope included safety, performance, and application testing
Meets IEEE 519, 1547
Power factor of 0.96
Less than 1-sec response
time to any dispatch level
Over 90% round-trip
efficient in regulation test
Operational 2 x 1MW system installed at IPL substation.
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Four second dispatch area control error (ACE) signal on 1MW system
(4 hr test) shows manageable thermals due to high system efficiency.
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Advanced batteries provide “instant” response to +1MW to -1MW swing.
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An AES commissioned dynamic simulation study of NYISO, PJM,
and CAISO shows significant system benefits from energy storage
systems with 15 min of storage capability.
Conclusions:
“…What is extremely interesting is that the effectiveness of the storage
device increases if the AGC is adapted to take advantage of a fast-acting
device that also needs to be "repaid" to restore its energy levels in a finite
period of time. The improvement in ACE itself is not the major benefit but
the ability to achieve regulation services using storage devices with lower
energy-to-power ratios (shorter duration periods) may be very important.
The reduced capital cost implied by the lower energy-to-power ratio
translates into lower overall costs for regulation services from the storage
device.”
“Storage devices responding to the filtered ACE signal are more effective
than conventional generation at providing AGC regulation, in terms of
system ACE performance, when used as described in this paper. This
strongly implies that a lesser MW amount of regulation procured from
storage and utilized as the primary resource for responding to ACE can
be used as compared with the volume of regulation procured today from
conventional resources.”
“Depending on the relative extent of storage used for regulation, the use
of storage also results in decreased regulation signals to conventional
units, which provides benefits in terms of incremental maintenance and
possibly reduced adverse emissions effects.”
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Commercial Project Example: Spinning Reserve Replacement in Chile
12MW for 20 minutes system comprised of 8 containers of
Advanced Lithium-ion storage
Increases energy sales from existing power plant by 4% by sell
additional 12MW
Received local system operator approval based on transient
system study
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Commercial Project Example: Spinning Reserve Replacement in Chile
50 Spinning
Reserve events per
year
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Commercial Project Example: Spinning Reserve Replacement in Chile
Plant with 20MW Reserve
Simulated loss of
332MW of generation.
Plant with 8MW Reserve
and 12MW Storage
Improved frequency response versus power plant.
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Renewable Integration Opportunity: Wind Projects
Problem:
Curtailments due to
transmission constraints are
limiting delivery to customer
under PPA
Duty Profile:
At least a 20MW system
with 4-5 hrs of charge and
discharge capability per day
Technical
Solution:
Premium Power ZincFlow2000 Flow Battery 40 x
2.8MWh 1000kW/500kW
units
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Internal architecture
Ops
Center
Internet
Comms
BOX
DNP
Relay
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Interconnection Scheme
Grid
The project consists of a
modular system, easily
serviceable, and
sectionalized into
inverter sections
supplying a common
battery string.
Grid protection meets
utility requirements
The system is connected
to the operations center
Step-up Transformer
Disconnect / Switchgear
Isolation Transformers
Internal Load
Inverters
Batteries
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Inverters are “off-the-shelf” and proven.
Trusted PCS Suppliers:
ABB
American Superconductor
Parker Hannifin
S&C
Siemens
Parker 1 MW Inverter System
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System benefits from a storage enabled grid:
“Better and Cheaper Today”
–Increasing capability of existing generating units by delivering
ancillary services from dedicated energy storage units.
–Same cost for better quality service – “faster response to
variations”
–Better use of existing assets – “steady throttling of plants”
“Enable the Future”
–Faster response to support varying nature of new supply.
–Lower emissions – “recycled energy”
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