1

1

EPRI Intelligrid / Smart Grid Demonstration Joint Advisory Meeting

March 3, 2010

Thomas J. WalkerEmeka Okafor

Community Energy Storage Presentation & Simulation Results

2

Energy Storage Applications in UtilitiesEnergy Storage Applications in Utilities

2

3

Matching Storage Options to Utility NeedsMatching Storage Options to Utility Needs

Storage Technologies

Utility Applications

Charts from www.electricitystorage.org

4

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

3

5

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 ?

6

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

4

7

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.

8

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

5

9

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

10

Load Following Peak Shaving

Circuit Demand

6

11

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

12

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:

7

13

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

14

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

8

15

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

16

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

9

17

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

18

CES LayoutCES Layout

10

19

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:

20

AEP-EPRI SMART GRID DEMOPerformance of a fully integrated and robust smart grid

from the RTO through to end-use customers.

11

21

AEP Approach to SG Technology Simulations

22

AEP Simulation – South Bend

12

23

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

24

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

13

25

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

26

Scheduled Discharge(or Charge)

Simple but discharges a fixed amount of energy, even on the low peak days

14

27

• 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

28

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)

15

29

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

30

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.

16

31

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 – tjwalker@aep.com

Emeka Okafor – cokafor@aep.com