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Advances in control systems and grid connection switchgear for
energy storage and microgrid projects
John Vernacchia – segment manager, alternative energy
2nd IBESA U.S. Storage Day at SPI
September 10, 2017
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Rail Renewables Residential Utilities Vehicles Water/wastewater
Machine building Marine
Mining, metals
and minerals
Mobile machinery
and equipment Oil and gas Pharmaceuticals
Aerospace Buildings Data centers Food and beverage Government Healthcare
Solving industry’s toughest power management
challenges around the world.
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Providing power management technologies
that are more reliable, efficient and safe.
Dedicated to improving people’s
lives and the environment.
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U.S. energy storage market snapshot - SEPA
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Grid connected
switchgear
Energy storage
system controller
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Beyond the battery and inverters: Utility-scale energy storage system elements
• DC switching and protection
• DC bus and/or flex bus
• Cable tray for battery cables
• Medium-voltage transformers
• AC grid interconnection switchgear
• Energy storage system controller
Intelligent control and protection solutions are essential to supporting large-scale energy storage systems: enabling broader new functionality, while enhancing safety and reliability.
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DC switching and protection is not trivial
• DC switches provide a means to disconnect the battery containers or racks
• DC fuses provide short circuit current interruption protection
• Battery system short circuit current requirements are much higher than solar systems!
• Battery systems: 30 to 50 kA typical
• Solar systems: 5 to 10 kA typical
• Battery and solar applications challenging
standards and component performance:
• Battery system DC bus: 1500 Vdc and 50 kA;
some request up to 100 kA
• Solar system AC bus: 800 Vac 35 kA
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Inverter architecture dictates AC grid connection
Inverter architecture Larger kW (central) Smaller kW (distributed)
Typical inverter characteristics • 500 to 2500 kW
• Typically outdoor rated
• Pad or skid mounted
• Air or liquid cooling
• 50 to 250 kW
• Typically indoor rated
• Rack or floor mounted
• Air cooling
Low voltage AC switchgear • May not be required
• LV switchboards aggregate
connections from smaller
inverters
Medium voltage transformer • Steps up inverter output voltage
to grid voltage
• 480 Vac to 35,000 Vac
• Steps up inverter output voltage
to grid voltage
• 480 Vac to 35,000 Vac
Medium voltage AC switchgear • Recloser
• Padmount
• Metal-enclosed
• Metal-clad
• Recloser
• Padmount
• Metal-enclosed
• Metal-clad
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AC grid connection storage project examples
Smaller distributed
inverters
with LV switchboards
Large central inverters
with direct bus connection to
MV transformers
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Energy storage project profile - System with a large kW central inverter
• Size: 2 MW / 8 MWh
• Location: California, USA
• Application: Renewable balance
• Battery type: Lithium ion
• Commissioned: December 2016
• AC grid connection content:
• Medium-voltage switchgear
• Medium-voltage liquid filled
transformer
• Low-voltage switchboard
• B-line series cable tray
• Commissioning services
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Energy storage project profile - System with smaller kW distributed inverters
• Size: 37 MW
• Location: California, USA
• Application: Renewable balance
• Battery type: Lithium ion
• Commissioned: December 2016
• AC grid connection content:
• Medium-voltage switchgear
• Medium-voltage liquid filled transformer
• Low-voltage switchboards
• Commissioning services
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Energy storage control system
• Interface between battery vendor BMS and utility control system
• Energy storage specific applications
• frequency regulation
• renewable firming
• load shifting
• etc.
• However, it may be required to do more than just energy storage
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Energy storage can be one element of a larger microgrid
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Energy storage / microgrid control system
• Modular and scalable for utility energy storage
or microgrid applications
• Flexible to expand and control other forms of
Distributed Energy Resources (DER)
• Optimize renewable energy assets
• Interface to controllable loads and demand
response software
• Interface to building or utility SCADA system
• Can operate in both grid connected and
islanded modes
• Photo: operational microgrid system at Eaton’s Power System Experience
Center near Pittsburgh, PA with Power Xpert Energy Optimizer controller
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Energy storage / microgrid control architecture
Fuel Cell Engine Generator Energy Storage Photovoltaic Controllable Loads
To Upstream Grid
IEC-61850
Local Controller -
Fuel Cell
To Upstream Control
Local Controller -
Gen Set
Local Controller -
Load
System Controller
PCCBreaker/Recloser
HMI
LocalController -
Energy Storage
Local Controller -
PV
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System Balance
• Generation and
demand priority
management
• Fast load
shedding
• Dynamic
demand
response
• Dynamic energy
storage
management
• Protection and
fault isolation
Frequency &
voltage control
• Islanded
generator Freq.
control
• Generation-
demand
balancing
• Supporting
renewable
dynamics
• Ramp rate
control
• Ancillary services
• Energy storage
integration
Seamless
islanding
• Unintentional(Se
amless) islanding
• Fast grid-fault
detection,
isolation and
safety interlocks
• Load shedding
• Source
management
• Grid
reconnection
Lowest cost
• Utility Demand
Response
functionality
• Energy arbitrage
• TCO
optimization
• Fossil fuel
conservation
• Peak shaving
• Load shifting
• Conservative
voltage
regulation
Renewable
optimization
• Smart inverter
controls
• Energy storage
integration
• Adaptive system
to weather and
price forecast
• Renewables
maximization
option to save
fossil fuel
• Ramp rate
control
• PV curtailment
System Design
• Open Comm
standards
• SCADA &
enterprise
interface
• Modular, Pre-
engineered
templates
• Legacy asset
compatible
• Adaptable to
future asset
changes
Energy storage / microgrid control design and use cases
Black Start
• Gen source
start-up
• Sequencing
• PQ stabilization
• Load sequencing
& management
Black Start
• Safety interlock
for grid isolation
• Gen and
renewable
source start-up
• Paralleling
sources
• Power Quality
stabilization
• Load sequencing
& management
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Seamless
islanding
Energy storage / microgrid design and use cases
Immediate response to grid separation
• High-speed isolation from grid
• Block inadvertent reconnection
• Microgrid source outputs change to carry internal load
• Microgrid sources regulate voltage & frequency
• Excess load is shed to maintain stability
Sustained control
•Manage sources and loads to optimize stability and meet secondary targets (maximize renewables, minimize fuel consumption, etc.)
Return to grid
•Ensure stable grid supply
•Coordinate microgrid voltage and frequency to match grid
•Supervise resynchronization
•Re-balance sources & loads to achieve grid-connected targets
Breaker
Opening
Load
voltage
Microgrid
Source
Current
Intentional Islanding
Under certain conditions (e.g. severe weather) the microgrid may be islanded intentionally
•Microgrid sources and loads varied to achieve net-zero power flow from utility
•Microgrid intentionally isolates from the grid
•Microgrid sources provide voltage and frequency control
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Black Start
• Gen source
start-up
• Sequencing
• PQ stabilization
• Load sequencing
& management
Black Start
Energy storage / microgrid design and use cases
Start Microgrid from “Black” state (no sources)
• Isolate from grid
•Block inadvertent reconnection
•Loads disconnected from sources
•First source started & connected, providing stable voltage & frequency to a portion of the microgrid
• Intelligent sequencing of additional microgrid sources and loads to maintain stability
•Transition to standard islanded operation
Renewable
optimization
Renewable Optimization
•Sources within the microgrid (esp. energy storage) smooth variations in renewables
•Combined with storage and conventional generation, variable renewables become viable sources in islanded applications
•Smart inverter controls enable inverters to be used for Var / Voltage control
•Ramp rate control
•PV curtailment
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Energy storage / microgrid design and use cases
Source: DOE Storage Handbook 2014
• Ancillary
services
• Demand
response
• Energy
arbitrage
• Peak shaving
• Load shifting
A variety of sources combined with intelligent source and load control provide grid-tied functionality
• Net Demand Response (combination of load shedding and generation sources)
• Net Demand Management (peak shaving, load shifting, load shedding)
• Energy cost optimization
Microgrid sources, especially energy storage, have additional use cases:
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Energy storage project profile - energy storage / utility microgrid controller
• Size: 5 MW system
• Location: Oregon, USA
• Application: Utility distribution microgrid
• Battery type: Lithium ion
• Commissioned: October 2012
• Grid connection content: • Medium-voltage AC switchgear
• Medium-voltage transformer
• Low-voltage AC switchboards
• Metering
• UPS
• Energy storage utility feeder microgrid
controls
• Commissioning services
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Energy storage project profile - Not just North America
Amsterdam Arena
• 3 MW total / 2.8 MWh
• Powering on-site electrical distribution
feeders and utility-connected transformers
• Incorporating recycled and new batteries
Eaton collaborations in action
• Eaton xStorage Building solution
• Eaton/Nissan Li Ion battery racks
• Eaton UPS/Grid Storage inverter platform
Applications
• Frequency regulation
• Peak shaving
• Backup power for arena events
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Eaton Experience Centers in Pittsburgh and Houston provide customized training
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Thank you
• John Vernacchia, segment manager,
alternative energy, Eaton
• Booth #3175
• www.eaton.com/energystorage
• www.eaton.com/microgrid