1. Energy Storage:
New Capabilities for the
Electric Grid –
The Tehachapi Energy
Storage Project
Next Generation Batteries 2015
April 21-22, 2015
San Diego, CA
Loïc Gaillac
Advanced Energy Storage Group Manager
Advanced Technology
Southern California Edison
Kevin Fok
Senior Project Manager
Energy Solution Company
LG Chem

2. Introduction
• Tehachapi Energy Storage Project (TSP):
– 32 MWh, 9 MVA (8 MW, 4 MVAr) Battery Energy Storage
System (BESS)
– Located at Monolith Substation in the Tehachapi Wind
Resource Area
– Jointly funded by Southern California Edison (SCE) and the
United States Department of Energy (DOE)
• SCE contracted with LG Chem. to:
– Design, construct, and maintain the system for a two-year
measurement and validation (M&V) period
• M&V period includes:
– Collection of BESS and electric system data
– Analysis of the project’s effect on the regional transmission
network
– Gaining experience and knowledge about the operation of a
large BESS
2

3. Project Objectives
• Test the BESS as a system reliability and/or market
driven device
– Demonstrate the performance of a lithium-ion Battery
Energy Storage System for 13 specific operational uses,
both individually and bundled
– Share data and results with CAISO, CEC, CPUC, DOE,
and other interested parties
– Assist in the integration of large-scale variable energy
resources
• Integrate battery storage technology into SCE’s
grid
– Test and demonstrate smart inverter technology
– Assess performance and life cycle of grid-connected
lithium-ion BESS
– Expand expertise in energy storage technologies and
operations
3

4. • 14 million customers: one of the
largest utilities in US
• 125 years of service
• Award-winning energy efficiency
and demand response programs
Southern California Edison
Committed to
safely providing,
reliable and
affordable electric
service
4

5. LG Group
5
LG was founded in 1947 as the first Korean chemical company and has successfully expanded its
business portfolio to a broad range of products and solutions in the chemical, electronics, and
telecommunications and services sectors
Chemicals
Electronics
16
17
16
LG Chem
LG Hausys
LG Life Sciences
LG Household & Healthcare
…
LG Electronics
LG Display
LG Innotek
LG Siltron
…
LG U+
LG CNS
LG International
SERVEONE
...
 Founded – 1947
 Revenue (2014) – $148B USD
 Employees – 226,000
Telecomm-
unications
& Services

6. • Located in the Tehachapi
area, California’s largest
wind resource
• Massive wind development
potential (up to 4,500MW)
driving grid infrastructure
• Installed at SCE’s Monolith
Substation
• 6,300 ft2 building
• Connected at sub-
transmission level through a
12/66kV transformer
6
BESS facility at Monolith
Substation
BESS facility and 12kV/66kV
transformer
TSP Facility

7. TSP Layout
7

8. System
Specifications
• Battery Storage
System
– Li-Ion
– Manufactured by LG
Chem.
– 32MWh usable
• Power Conversion
System
– 9MVA
– 12kV connected
– Manufactured by
ABB
8

9. System Design
• Several design iterations performed
• Significant challenge to meet required
footprint
• HVAC study for thermal analysis
– Modified and optimized thermal management
based on:
• Battery rack temperature distribution
• Maximum temperature differences
• Temperature transients
• Analysis of fire suppression system
– Performed destructive tests with representative
battery elements using different spatial
configurations for external short circuit, and thermal
runaway conditions
9

10. System Design (continued)
• Met stringent standards
– Electrolyte: Evaluated using Cup Burner Test NFPA 2001 Standard on Clean Agent Fire
Extinguishing Systems (2012 edition)
– Battery Cells: UL Listed (UL 1642)
– Battery Modules: UL Listed (UL 1973)
– Battery Rack with Modules Installed: Electromagnetic compatibility (FCC Part 15B)
– Battery Protection Unit: Electromagnetic compatibility:
• Conducted Emission EN 61000-6-3:2007+a1:2011
• Electrostatic Discharge(ESD) EN 61000-4-2:2009
• Radiated RF Electromagnetic Fields EN 61000-4-3:2006+A2:2010
• Electrical Fast Transients / Burst(EFT) EN 61000-4-4:2004+A2:2010
• Surges EN 61000-4-5:2006
• Immunity to Conducted Disturbances EN 61000-4-6:2009
• Power Frequency Magnetic Field Immunity Test EN 61000-4-8:2010
• Voltage Dips and Interruptions EN 61000-4-11:2004
– Battery Racks with Modules Installed:
• Tested to IEEE 693-2005 (IEEE Recommended Practice for Seismic Design of Substations)
• Meet Zone 4 seismic requirements
– PCS modules:
• UL Listed (UL 1741)
• Site Security System
– SCE designed and completed security system to substation standards
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11. System Configuration
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x 56 x 18 x 151 x 4
Cell Module Rack Section System
Quantity 608,832 10,872 604 4 1
Voltage 3.7 V 52 V 930 V 930 V 930 V
Energy 60 Wh 3.2 kWh 58 kWh 8.7 MWh 32 MWh (AC)
Weight 380 g 40 kg 950 kg N/A N/A
How to get 32MWh from 60Wh battery cells

12. Construction
• Dealt with challenges of a remote area
• Site constraints with local railroad tracks, high
pressure gas lines, substation
• Very limited storage space
• Many “non-battery” tasks
• Windy weather
• Rodents and insects
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13. Construction

14. Construction
• Text
14

15. Commissioning
• Project team members collaborated closely to
develop the commissioning plan
• Plan involved several iterations of reviews and
revisions
• PCS controls, Battery and overall system
controls, and IT components were
commissioned in parallel whenever possible
• June 2014: BESS delivered 32 MWh during initial
commissioning tests
• September 2014: Grand Opening Ceremony
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16. Grand Opening Ceremony
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17. TSP Testing and Evaluation
• Operational Uses
• Core Tests
• System Operational
&Validation Challenges
• Mini-System Testing
• System Acceptance
Testing
• Preliminary
Characterization Testing
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18. TSP 13 Operational Uses
• Transmission
– Provide voltage support/grid stabilization
– Decrease transmission losses
– Diminish congestion
– Increase system reliability
– Defer transmission investment
– Enhance value and effectiveness of
renewable energy-related transmission
• System
– Provide system capacity/resource adequacy
– Integrate renewable energy (smoothing)
– Shift wind generation output
• Market
– Frequency signal/response
– Spin/non-spin/replacement reserves
– Ramp management
– Energy price arbitrage
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19. 8 Core Tests
1) Provide steady state voltage regulation and dynamic voltage
support at the local 66 kV bus
2) Perform Test 1 while operating under any mode and performing
real power injection/absorption required under such mode
3) Charge during periods of high line loading and discharge during
low line loading under SCE system operator control
4) Charge during off-peak periods and discharge during on-peak
periods under SCE system operator control
5) Charge and discharge seconds-to-minutes as needed to firm
and shape intermittent generation in response to a real-time
signal
6) Respond to CAISO control signals to provide frequency
regulation
7) Respond to CAISO market awards to provide energy and
spin/non-spin reserves
8) Follow a CAISO market signal for energy price
19

20. System Pre-operation Challenges
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Challenges Resolutions
System integration between all
components; Sub-components may
be mature but system integration is not
Assess system performance, safety
and reliability prior to field
deployment
System Acceptance Testing (SAT) is
impractical on site
Introduced multi-step Acceptance
testing based on lab evaluation of:
• Communication system by SCE IT
group
• PCS controller on the RTDS (Real
Time Digital Simulator)
• Mini-system
Framework around control ownership
in a non-vertically-integrated utility:
• Generator controlled by Power
Supply Group
• Grid reliability asset controlled by
Grid Control Center
• Shared optimized asset
Engage stakeholders and identify
requirements to be completed for
(inter)connection, deployment and
control

21. System Validation Challenges
• Large energy storage systems are modular
– Comprised of AC and DC subsystems
– Scaled by adding additional components in
series/parallel
– Multiple manufacturers
– Requires complex integration
– Increased likelihood of problems
• Utilities need to assess safety and reliability prior to
field deployment
• Issues with testing large systems in the field
– Grid/personnel safety
– Geographic distance
– Need to exchange significant power at will
– Hardware/firmware/software problems can take many
months to solve
21

22. System Validation Approach: Mini-System Lab Testing
Mini-System Full System
Footprint 77 ft2 6300 ft2
building
Power 30 kW 8 MW
Energy 116 kWh 32 MWh
Power
Conversion
System
One Mini-
Cabinet
Two 40-foot
containers
Sections 1 4
Banks 1 32
Racks 2 604
Modules 36 10,872
Cells 2,016 608,832
Mini-System for Sub-scale Testing
Mini-System enables subscale testing in the lab before full-scale
operation of the BESS at Monolith Substation
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23. Battery Racks
Power
Conversion
System (PCS)
Mini System at SCE laboratory

24. Site Energy Controller Battery Section
Controller
PCS & DC
Switchgear
Controls
Mini System at SCE Laboratory (cont.)

25. Mini-System Testing Key Findings
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Key Findings Benefits
Discovered and resolved critical
safety and operational aspects
regarding the battery system and
PCS
Minimum impact of safety and
operational issues, quick to
resolve
Several iterations of
software/firmware upgrades
required
Significant time and resources
saved due to upgrades
performed in the lab at subscale
level versus full-scale at remote
substation location
24/7 operation for more than 4
months prior to full system
commissioning yielded feedback
to implement many additional
functional upgrades
System operation and features
have been enhanced
(optimized control algorithms)

26. System Acceptance Testing
• Purpose
– To verify that the BESS met all technical requirements
including the ability to deliver 32 MWh of energy over four
hours of continuous discharge at 8 MW
• Outcome
– BESS successfully completed all commissioning tests in two
weeks without any technical issues
26

27. Initial Operation – System Acceptance
Testing
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Full Discharge:
• 8MW - 4 hours
• 32MWh

28. Characterization Testing
• Background
– System acceptance tests included a discharge
capacity test to verify 32 MWh discharge
– Capacity test did not measure round trip efficiency
or operate system under continuous cycling profiles
• Objectives
– To characterize behavior and performance of
system during continuous full charge/discharge
cycles at 8 and 4 MW
– To analyze power, energy, efficiency, and
temperature data from battery system, PCS, and
point of common coupling

29. Preliminary Characterization Results
• Completed testing at 8 MW in December 2014
• Analysis excludes auxiliary loads for battery
building and PCS (to be included in subsequent
tests)
• Test Conditions
• BESS Operating SOC Range: 2.5% to 98%
• Rest Time Between Charge and Discharge: <15 min
• All measurements taking at the 66kV point of
common coupling
Average
Charge
Energy
Average
Discharge
Energy
Average
Round Trip
Efficiency
34.93 MWh 31.64 MWh 90.6 %

30. Current Status
• In January 2015, a medium voltage transformer failure
occurred in one PCS with no impact to other
equipment
• Root cause analysis showed that the design of
transformer did not support all operational
requirements
• Transformers were redesigned and the facility was shut
down to facilitate replacement
• Operation of the system was restored on April 18th, 2015
• Lessons Learned (vendor perspective)
– Evaluate all requirements and associated impacts on each component’s
design
– Facilitate component replacement in design
– Real operations provide real learning
– Deployment experiences are valuable for all stakeholders
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31. Final Thoughts
• Installation, deployment and preliminary operation
of large-scale ESS has:
– Provided key learning to facilitate future deployments
– Demonstrated the benefits of Mini-System testing
– Shown that all components are critical, including
transformers
• Close collaboration between utility and turnkey
system provider has accelerated lessons learned
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