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EPRI Intelligrid / Smart Grid Demonstration Joint Advisory Meeting
March 3, 2010
Thomas J. WalkerEmeka Okafor
Community Energy Storage Presentation & Simulation Results
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Energy Storage Applications in UtilitiesEnergy Storage Applications in Utilities
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Matching Storage Options to Utility NeedsMatching Storage Options to Utility Needs
Storage Technologies
Utility Applications
Charts from www.electricitystorage.org
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The Evolution of the Electric Utility SystemThe Evolution of the Electric Utility System
Before Smart Grid:One-way power flow, simple interactions
After Smart Grid:Two-way power flow, multi-stakeholder interactions
Adapted from EPRI Presentation by Joe HughesNIST Standards Workshop
April 28, 2008
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Smart Grid Enables Energy StorageSmart Grid Enables Energy Storage
Adapted from EPRI Presentation by Joe HughesNIST Standards Workshop
April 28, 2008
But where is the best location/size for the storage ?
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Energy Storage OptionsEnergy Storage Options
Grid Storage Options
At Substations or Near Large Customers
(Few MWs / 4-6 hours)
Small scale (CES) Fleet(100’s of 25 kW units with several hours of discharge)
EV-approved Batteries
(safer & commodity cost)
Non EV-Approved
Batteries
Lead Acid (low cost)
Flow Batteries
Fixed Transportable
Li-ion Trailers
Flow Batteries
NaS Li-ion(Compact & Efficient)
NewEV-type Batteries
UsedEV Batteries
(Limited Life but Low Cost)
Strategically Placed(100 MWs /
minutes to hours)
Li-ion(or other)
Flywheels
1- System Level1- System Level 3- Grid Edge3- Grid Edge2- Substation Level2- Substation Level
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AEPAEP’’s 1s 1STST Substation BatterySubstation Battery
2006
1MW, 7.2 MWh of NaS battery
Deferred New Substation
Tyler Mountain Feeder12 kV bus
North Charleston Feeder
West Washington FeederVoltage Regulator
46kV/12kV Transformer
12/16/20 MVA
46 kV bus
This First Utility-Scale NAS Project was Partially Funded by DOE/Sandia
NGKS&CAEP
Chemical StationCharleston, W.VA.
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AEP 2006 Project – Peak Shaving
• Scheduled trapezoidal Charge & Discharge profiles
• Improved the feeder load factor by 5% (from 75% to 80%)
• Reduced the oil temperature of the 20MVA supply transformer by about 4 degrees C
+ 1.2 MW Charge
- 1.0 MW Discharge
2007
2006
2008Three Successful
Years of Peak
Shaving
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AEP Storage 2010 – 11MW, 75MWh
1 MW, 7.2 MWh installed in 2006• Deferred substation upgrades
3 - 2MW,14.4 MWH Commissioned in 2009• Implemented “Load Following”
• Demonstrated “Islanding”
4MW, 25MWh substation will be on-line in March 2010
The New “Islanding” feature is Partially Funded by DOE/Sandia
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Load Following Peak Shaving
Circuit Demand
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Live Islanding ExperienceLive Islanding Experience• NaS Storage Site : Balls Gap, Milton, WV• Outage Date: Dec 18, 2009• Outage Cause: Heavy snow• Island Size: 25 Customers (small area)• Time to island customers: 2 min.• Power Outage Duration: 2 Days• Time to Exit Island: 6 sec. (not Synchronized)• Average Island Load: 167 kW
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To Optimize StorageTo Optimize Storage
1. Very Close to Customers• Backup Power, • Buffer Customer Renewables
2. Grid-Connected• Load Leveling, • Volt / VAR support
3. Utility-Operated• Load Diversity (multiple customers on one storage)• Improved Safety• Optimizing Grid Performance
4. Utility-Owned• Standardization & Commodity Pricing• Socializing the Cost
Need an energy storage system with the following FOUR key features:
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CES(Community)
Devaluators:• Aesthetics
Locational Value of Electricity StorageLocational Value of Electricity Storage
120 V240 V69 kV 4 to 34 kV 480 V138 kV345 kV765 kV
Storage Value
Central Units Distributed Units
Devaluators:• No Backup• High Security Risk• Less effect on losses
Pumped Hydro(Central)
Devaluators:• Safety Concerns• No Load Diversity• No Cost Sharing• Little Grid Benefits •No Standardization
ResidentialNaS
(Substation)
Devaluators:• Complex Islanding• Storage Size & Location•Medium Security Risk
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Migratory Path of Energy Storage Migratory Path of Energy Storage –– AEPAEP
Large Central Units
Storage at Grid Edge
Substation Batteries
Graphics adapted from an EPRI Presentation by Joe Hughes
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Community Energy Storage (CES)Community Energy Storage (CES)
CES is a fleet of small distributed energy storage units connected to the secondary of transformers serving a few houses controlled together to provide feeder level benefits.
240 / 120VVoltage - SecondaryLi-IonBattery - PHEV> 85%Round Trip AC Energy
Efficiency
75 kWh Energy25 kWPowerValueKey Parameters
Functional Specifications for CES are “OPEN SOURCE”In 2009 EPRI hosted open webcasts to solicit industry wide input.
www.aeptechcenter.com/ces
25 KVA
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CES CES –– A Virtual Substation BatteryA Virtual Substation Battery
Local Benefits:1) Backup power2) Voltage correction3) Renewable Integration
Substation
Power LinesCommunication and Control Links
CES
CES is Operated as a Fleet offering a Multi-MW, Multi-hour Storage
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CES CES –– A Virtual Substation BatteryA Virtual Substation Battery
Communication & Control Layout for
CES
Utility Dispatch Center /SCADACES Control Hub
Substation
Power LinesCommunication and Control Links
Integration Platform
CES CESCESCES
CES is Operated as a Fleet offering a Multi-MW, Multi-hour Storage
Grid Benefits:4) Load Leveling at substation5) Power Factor Correction6) Ancillary services
Local Benefits:1) Backup power2) Voltage correction3) Renewable Integration
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CES LayoutCES Layout
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Benefits of CESBenefits of CES
1. More reliable Backup Power to customers (closer)
2. More scalable, flexible implementation (many small units)
3. More efficient in buffering customer renewable sources
4. More synergy with Electric Vehicle batteries (competition)
5. Easier installation and maintenance (240 V)
6. Unit outage is less critical to the grid (smaller)
While CES is, Functionally, a Multi-MW, Multi-hour Substation Battery, It has Inherent Advantages over Larger Batteries located in Substations:
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AEP-EPRI SMART GRID DEMOPerformance of a fully integrated and robust smart grid
from the RTO through to end-use customers.
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AEP Approach to SG Technology Simulations
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AEP Simulation – South Bend
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Challenge: Need for Peak Shaving.
Set Trigger Level
Ideal and simple if stored energy is sufficient. However, there is no assurance that stored energy would be adequate and , therefore, peak shaving could be completely ineffective.
Inadequate energy on high‐peak days makes peak shaving ineffective
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Time Triggered Discharge Parameters
• Set Points:– Start Time (same for all days)– Minimum Demand below which no energy should be discharged
2:00 pm Day1
2:00 pm Day2
2:00 pm Day3
No Discharge on Low demands
Minimum Demand at for discharge
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Time Triggered Load FollowingSimulation Results
Time-triggerred Load Following
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
Load
(kW
)
Load without Battery
Load with Battery
AUGUST 10th - 20th, 2009
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Scheduled Discharge(or Charge)
Simple but discharges a fixed amount of energy, even on the low peak days
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• Set Points:– Start Time– Ramp Up duration (min) - Tup
– Flat Duration (hours) - tFLAT
– Ramp Down Duration (min) tDN
Scheduled Discharge Parameters
Start Time
Tup tFLATtDNPower
• Dynamic Inputs:– Unit Available Energy– Status (Manual, etc.)– Unit output (kW, kVAR)– Voltage
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CES Unit Power & Energy
Power
Power
Power
Case 1 – Reported Available energy is sufficient
Case 2 – Available energy is not sufficient
1.Planner Option (Keep Duration, reduce Power)
2.Dispatcher Option (Keep Power, reduce duration)
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Scheduled Discharge Simulation Result
Scheduled Discharge
0
1000
2000
3000
4000
5000
6000
7000
8000
Load
(kW
)
Load without Battery
Load with Battery
Aug 3rd Aug 4th Aug 5th Aug 6th Aug 7th
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Lessons Learned & Going Forward….
• Adequate storage capacity (energy) is needed to meet peak shaving (power) requirements with variable load behavior.
• Adaptive storage dispatch will permit optimal utilization of storage.
• Performance for pf correction will be analyzed.• Cross-technology: CES will provide flexible integration into other DER schemes like VVC.
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ConclusionsConclusions
•AEP plans to deploy Community Energy Storage (CES) as part of its gridSMARTSM initiatives.
•Virtual Power Plant Simulator enables the utility to analyze the performance of a fully integrated and robust smart gridfrom the RTO through to end-use customer appliances.
Tom Walker – [email protected]
Emeka Okafor – [email protected]