Energy Storage as a Key Element in Smart Grids

Ross Baldick, Department of Electrical and

Computer Engineering

1Copyright © 2017

Bill Muston

Oncor

Spring 2017Final #2 Version

Outline

Why Now? Cost trend for energy storage

Energy Storage System (ESS) Definition

Roles – Bulk power, wires, customer and DER

Utility distribution systems & ESS

Power, energy, reactive

Delivery asset alternative, reliability, microgrid

Multiple uses of a single ESS

Regulatory & market construct considerations

2Copyright © 2017

Acknowledgements

Thanks to Oncor for allowing the use of slides and knowledge

Thanks to Nathan Kassees and Mila Hunt at Oncor for partnership is developing slides, content, and homework assignment

Copyright © 2017 3

ONCOR AT A GLANCE

Texas' largest regulated transmission and

distribution utility

Serves over 3.3 M customers/meters

402 Cities and 91 counties

3,784 Employees

REGULATE

D

TRANSMISSION

DISTRIBUTION

METERING

COMPETITIVECOMPETITIVE

GENERATIONRETAIL

ELECTRIC

PROVIDERS

Outline

Why Now? Cost trend for energy storage

Energy Storage System (ESS) Definition

Roles – Bulk power, wires, customer-sited and DER

Utility distribution systems & ESS

Power, energy, reactive

Delivery asset alternative, reliability, microgrid

Multiple uses of a single ESS

Regulatory & market construct considerations

5Copyright © 2017

WHY NOW?

• Energy storage – to complement grid functions at

substations and in distribution systems – has never been

utilized widely

• Traditional equipment is economical and works well

• High cost of storage for proven types of storage

• Technical maturity of many newer storage technologies is not yet

proven, predictable, and reliable, as compared to traditional utility

equipment

• Commercial maturity – standardized performance needs for

distribution applications have not been established, and, therefore,

standardized products have not been widely available with

standard warranty for standard performance expectations

• BUT –

• Costs and maturity are changing rapidly

• Standardization thru common application types and functional

specifications is underway6

7GTM Research Storage Cost Outlook

Grid-Scale Storage Project Cost Forecast – Medium Duration (2-hour)

System Costs ($ per kWh) 2015 2016E 2017E 2018E 2019E 2020E

BOS $335 $299 $269 $241 $217 $195

Li-ion Battery $330 $304 $279 $257 $236 $217

Total $665 $603 $548 $498 $453 $412

Li-ionBattery

$330 $304 $279 $257 $236 $217

BOS $335

$299$269

$241$217

$195

$0

$100

$200

$300

$400

$500

$600

$700

legend 2015 2016E 2017E 2018E 2019E 2020E

Sto

rage S

yste

m C

ost

($/k

Wh)

Source: GTM ‘Grid-Scale Energy Storage Balance of Systems 2015-2020: Architectures, Costs and Players’

Used with Permission of GTM

Lithium-Ion Battery

Oncor Confidential - For Internal Use Only8

Anode - Copper conductor in Carbon, Titanium-

Oxide, or Silicon-Tin structure

1 - Lithium Ions release electrons and dissolve into

electrolyte

4 - Lithium Ions combine with electrons and layer

onto anode

Cathode - Lithium-Metal-Oxide or Lithium-Metal-

Phosphate structure

2 - Lithium Ions combine with electrons and

integrate with cathode

3 - Lithium Ions release electrons and dissolve into

electrolyte

ElectrolyteLiquid or Gel electrolyte of Lithium-Carbonate or

Lithium-Flouride Compound

Conductive to Lithium Ions (Li+)

Polymer Hydrocarbon barrier conductive to Lithium Ions

(Li+)

Outline

Why Now? Cost trend for energy storage

Energy Storage System (ESS) Definition

Roles – Bulk power, wires, customer-sited and DER

Utility distribution systems & ESS

Power, energy, reactive

Delivery asset alternative, reliability, microgrid

Multiple uses of a single ESS

Regulatory & market construct considerations

9Copyright © 2017

ENERGY STORAGE SYSTEM – ‘ESS’

• Energy stored in a form other than AC electricity

• The energy storage unit is ‘filled’ with energy from the

grid

• Conversion from AC to stored energy and back to AC

• Grid interface equipment and controls

• Energy storage unit internal controls to protect the asset

• Often called Battery Management System (BMS)

• A set of equipment that can be ‘placed’

• As used in these slide, an ESS is NOT pumped hydro or compressed air

energy storage where siting is driven by geography

10

BATTERY STORAGE SYSTEMS

11

Battery cell

Inverter

Grid

Electric Customer

BMS Controls

ESS Controls

Battery rack

Battery Array

Switch

Transformer

12

Source: DOE’s Sandia National Laboratory, Energy Storage Systems Program –

http://www.sandia.gov/ess/wp-content/uploads/2015/04/EsPositioningHandbook.png

http://www.sandia.gov/ess/publication/doeepri-electricity-storage-handbook/

Outline

Why Now? Cost trend for energy storage

Energy Storage System (ESS) Definition

Roles – Overview – Bulk power, wires, customer-sited and DER

Utility distribution systems & ESS

Power, energy, reactive

Delivery asset alternative, reliability, microgrid

Multiple uses of a single ESS

Regulatory & market construct considerations

13Copyright © 2017

BATTERY

TRANSMISSIONGENERATION

RETAIL ELECTRIC

PROVIDERS

DISTRIBUTION LINES

CompetitiveRegulated

GRID ENERGY STORAGE VALUES

15

BULK GRID

Wind & solar firming, smoothing and dispatch

Time-shift energy supply vs. need (eg. wind & solar) to meet market needs and/or energy arbitrage

Grid reliability services

• Supply regulation

• Frequency regulation

• Responsive reserves for grid contingency

• Fast response

DISTRIBUTION FEEDERS &

SUBSTATION

Support the local grid during upstream outages

Defer or substitute for traditional upgrades needed to support growing loads

Integrate distributed renewable sources (DERs) to the local grid to maintain grid stability & voltage control

CUSTOMER

Manage peak demand on the grid to limit demand charges

Smooth & firm customer-sited solar or wind

Time-shift energy from the grid or from customer-sited solar, such as to manage energy use under a time-of-use retail rate

Support islanded microgrid operation for critical services during grid outage

Focus of this lecture

ENERGY STORAGE USE CASES

16

• Various studies, projects, and organizations have

developed use cases for energy storage applications

• These use cases are generally high-level descriptions

and ESS performance expectations

• The following 2 slides show use cases from a very

recent study, the Lazard Levelized Cost of Storage v2.0

17

18

For further information on applications, cost, and

performance –

• See the Lazard Levelized Cost of Storage v2.0 –

• Examines the lifetime ownership cost for energy storage in a

variety of applications and of a variety of types of energy storage –

https://www.lazard.com/perspective/levelized-cost-of-storage-

analysis-20/

• See the DOE/EPRI Electricity Energy Storage Handbook

in Collaboration with NRECA 2013 version

• http://www.sandia.gov/ess/publication/doeepri-electricity-storage-

handbook/ (Update anticipated in 2017 does not appear to be

available at this point in time.)

19

http://www.nytimes.com/2010/11/07/us/07ttbattery.html

Electric Transmission Texas energy

storage project in Presidio, Texas.

• Commercial operation in 2010

• Serving transmission purposes

• http://www.ettexas.com/projects/presnas.asp

Slide compiled by Oncor from public sources

21

22 Slide compiled by Oncor from public sources

Outline

Why Now? Cost trend for energy storage

Energy Storage System (ESS) Definition

Roles – Bulk power, wires, customer-sited and DER

Utility distribution systems & ESS

Power, energy, reactive

Delivery asset alternative, reliability, microgrid

Multiple uses of a single ESS

Regulatory & market construct considerations

24Copyright © 2017

DISTRIBUTION SYSTEM USE CASES FOR ESS

• ASSET ALTERNATIVE – An asset to meet a portion of

growing local peak demand without requiring that

traditional upstream facilities be upgraded to meet that

demand

• RELIABILITY – Supply local downstream loads when the

upstream power is out

• INTEGRATE SOLAR – Maintain required feeder voltage &

power factor during rapid feeder power changes for

feeders with high solar penetration when clouds come

and go

25

ASSET ALTERNATIVE – Substation

• Meet the incremental peak demand on a substation

• When that incremental demand would create total substation

demand that is greater than what the substation equipment can

support

• Case 1 – The peak demand on substation equipment is

growing slowly

• A major substation upgrade or expansion is the primary or

traditional approach

• The cost of the upgrade would be high

• Case 2 – The peak demand on substation equipment is

expected to grow very rapidly

• The time required to implement traditional upgrades is longer than

the expected timing of the increased peak demand

• The cost required to quickly implement traditional upgrades in the

short timeframe would be prohibitive

26

ASSET ALTERNATIVE – Distribution Feeder

• Meet the local demand growth downstream on a feeder

• The demand growth will otherwise require that a portion

of the feeder that is upstream of the demand growth

would need to be upgraded

• The cost or lead time or community impact might be

limiting factors in upgrading the feeder

• Siting is available for a storage facility

29

RELIABILITY – At transformer serving customers

• Supply downstream loads with ESS when the upstream

power is out

• Goal: reduce total annual outage time as measured by SAIDI for

the affected portion of feeder

• Reduce outage times by utilizing storage for localized

supply while utility crews are correcting the outage and

restoring normal service

• Storage as the sole energy resource for the islanded segment of

the feeder

• Storage provides a less costly means to improve SAIDI than

traditional means

30

31

Purpose

• Evaluate effectiveness of deploying small-scale battery storage to bridge outages and improve local power quality

Details

• Six 25 kW lithium ion batteries

• Installation, testing and monitoring

Capacity

• These batteries are capable of bridging outages up to a few hours of duration

NEIGHBORHOOD STORAGE RELIABILITY INITIATIVE

NEIGHBORHOOD STORAGE RELIABILITY INITIATIVE

Distribution level outage backup, voltage regulation

25 kW, 25 kWh

Installed at single phase 120/240 secondary

1 at an Oncor facility

5 on Oncor System

Supports residential homes during outages and maintains

voltage within mandated levels (114 – 126 V)

32

Oncor Initial Installation at Oncor Facility Neighborhood in South Dallas

NEIGHBORHOOD STORAGE RELIABILITY INITIATIVE

Goals:

• Demonstrate the use of energy storage technology to improve

reliability

• Outage backup

• Voltage regulation

• Gather performance data to identify value of technology on system

• Efficiency

• Customer feedback

33

Example: Outage

34

ESS

Tie

Breaker

Example: Outage

35

ESS

Tie

Breaker

Example: Outage

36

ESS

Tie

Breaker

Normal Switching Scheme

37

CES = Community Energy Storage

Bypass Switching Scheme

38

CES = Community Energy Storage

NEIGHBORHOOD STORAGE RELIABILITY INITIATIVE

Location Selection

120/240 Single Phase

Test Installation (SOSF)

South Dallas Target Area

High SAIDI Feeders

Customer Verbal Approval

Available Space

39

SAIDI = System Average Interruption Duration Index

NSRI Testing

Inverter overload capability

40

0

20

40

60

80

100

120

140

160

180

200

0

5

10

15

20

25

30

28.7 32.7 37.2 41.9

Cu

rre

nt

(A)

Tim

e (s

)

Load (kW)

Inverter Overload

Time to Inverter Overload

RMS current

NSRI Testing

Open circuit island test

Oncor Confidential - For Internal Use Only41 Oncor Confidential - For Internal Use Only41

25.5 ms

Transition to

Inverter

Transition to

Grid

34.4 ms

NSRI Testing

25 kW Load Island Test

42

Transition to

Inverter

Transition to

Grid

26.7 ms

33.0 ms

NSRI Testing

Small Fridge Island Test (2 amp motor)

Oncor Confidential - For Internal Use Only43

26.0 ms

Transition to

Inverter

Large A/C Load Island Test

44

1 second later

Operational Settings

Based on ITI (CBEMA)

curve defining voltage

tolerance thresholds of

power supplies

NSRI islanding settings

based on this curve

45

Results

46

LocationNumber of Operations

Total Island Minutes Average Efficiency

1 7 872 125 95.41%

2 3 267 89 98.10%

3 5 453 91 97.49%

4 8 361 45 96.82%

5 3 231 77 97.53%

All 26 2184 84

Efficiency measured as energy in vs.

energy out over the life of the system

RELIABILITY – SEGMENT OF A FEEDER

• Storage as sole energy resource

• Sized based on specific statistics of outage and restoration times for that

local area

• Location of ESS unit based on feeder and load topology

• Adds technical requirements to ESS

• Provide magnetizing in-rush current to transformers and motor

start

• Supply fault current to fuses to clear smaller, typically single phase,

faults and return to operation

• Add distribution automation for sectionalizing for the

original fault location, fault isolation, sectionalizing, and

reconfiguration (FLISR)

47

RURAL FEEDER RELIABILITY PROJECT STUDY

Can an energy storage system (ESS) on a long, rural

distribution feeder improve the reliability of that feeder?

Can it support small towns at the end of long overhead

lines?

• These towns are vulnerable to extended outages

Reliability measured by SAIDI

ESS located downstream on the feeder

• At or near the small towns affected by outages

48

49 Oncor Proprietary and Confidential - Not for external distribution

Approaches Used Today to Improve Feeder Reliability

• Vegetation Management

• Feeder Maintenance

• Automation –

• Fault Location, Isolation, Service Restoration/Reconfiguration

• Distribution automation switching devices

• Autonomous communications and control

https://www.smartgrid.gov/files/B5_draft_rep

ort-12-18-2014.pdf

Fault Location, Isolation, and Service Restoration (FLISR)

An essential component for

successful FLISR operations is the

communications network for

remote monitoring and control of

technologies and systems. FLISR

communication networks require

increased resilience because they

must operate under conditions

where the grid itself is damaged or

not functioning properly. The two-

way communications network must

have sufficient coverage and

capacity to interface and

interoperate with a wide variety of

technologies and systems,

including various field devices and

DMS, OMS, and SCADA systems.

From U.S. Department of Energy report

Fault Location, Isolation, and Service

Restoration Technologies Reduce Outage

Impact and Duration

Long Rural Feeder

Traditional FLISR, non-ESS approach

Switches

New line

Existing line

Substation

Switches

Substation

52

Using Energy Storage to Improve Feeder Reliability

• Energy Storage System (ESS)

• Automation –

• Fault Location, Isolation, Service Restoration/Reconfiguration

• Distribution automation switching devices

• Autonomous communications and control

Long Rural Feeder

A battery that serves downstream customers when the upstream grid is

out

Transmission lines

Pockets

of load

Additional

pockets of load

Substation

GEOGRAPHIC REGION FOR THIS PROJECT

54

Area of interest is in

blue oval

Characteristics of the

area

• Agriculture

• Forestry

• Sparse population

FEEDER SELECTION CRITERIA

1. Consistently high SAIDI

2. Majority of faults along feeder backbone

3. Ties to other feeders not easily accessible

4. Minimum of a few hundred customers

5. No heavy industrial customers

6. Feeder length >40 miles primary 3-phase

7. Pockets of load located toward the end of the line

55

SAIDI = System Average Interruption Duration Index

Feeder B

56

73 Miles of Primary Feeder

379 Customers

4.3 kW of load/meter avg

2.3 MW of peak load

Feeder B Battery Solution

57

c

c

Automated

Switches

S

S

S

2 mi

Install N/O IRPC with Intelliteam II.

Install N/C IRPC with Intelliteam II.

R

Install N/CNova Form 6 Recloser

R

Honey Grove Substation

29,000 ft. of 3-#2 ACSR reconductor/rebuild

R

Install N/C IRPC with Intelliteam II.

Install/Upgrade regulators/controls [3 locations]

Install N/O IRPC with Intelliteam II.

31,000 ft. of 3-#2 ACSR reconductor/rebuild

8,000 ft. of 3-#2ACSR reconductor/rebuild

R

Install N/CNova Form 6 Recloser

N

Feeder B Alternative Solution

RURAL FEEDER – Lessons Learned

• Feeder in-rush current on blackstart via ESS imposes

additional specification and design needs, in order to

procure an ESS today for this specific application

• System protection requires adequate fault current from an

ESS to blow fuses on feeder lateral lines. This also

imposes additional specification and design needs, in order

to procure an ESS for this specific application

• Suggests to vendors of ESS a need to develop standard

options for ESS that incorporate in-rush current and fault

current needs

59

INTEGRATE SOLAR ON A DISTRIBUTION FEEDER

• Utility need: Maintain required feeder voltage & power

factor during rapid feeder power changes – when clouds

come and go for feeders with high penetration of solar PV

systems

• Utilize ESS to complement to deployed voltage & power

factor control, such as load tap changers (LTC), capacitor

banks, and voltage regulators, all of which were not

designed for frequent operation

• Utilize energy, power, and reactive capabilities of the ESS

• Frequent use of LTC’s, capacitor banks and voltage regulators will

wear them out, requiring higher maintenance

• Inverter is utilized for feeder voltage & reactive power management

• ESS main capability is utilized for other purposes

60

Outline

Why Now? Cost trend for energy storage

Energy Storage System (ESS) Definition

Roles – Bulk power, wires, customer-sited and DER

Utility distribution systems & ESS

Power, energy, reactive

Delivery asset alternative, reliability, microgrid

Multiple uses of a single ESS

Regulatory & market construct considerations

61Copyright © 2017

MICROGRID

• A microgrid is a group of interconnected loads and

distributed energy resources within clearly defined

electrical boundaries that acts as a single controllable

entity with respect to the grid. If desired, a microgrid can

connect and disconnect from the grid to enable it to

operate in both grid-connected or island-mode.

• Microgrid Key Attributes (Defining Characteristics):

• Grouping of interconnected loads and distributed energy resources

• Can operate in island mode or grid-connected if desired

• Can connect and disconnect from the grid if desired

• Acts as a single controllable entity to the grid

62

63

https://www.youtube.com/watch?v=hSOTfAOoGBs

Video of Oncor Microgrid

ONCOR MICROGRID OVERVIEW

Located at Oncor’s System Operations & Services Facility (SOSF)

What questions were we seeking

to answer by building a microgrid?

• What DER will be part of the

future grid and does it matter

where they are located?

• Will DER have an impact on

reliability or is the main driver to

be an economic generation

alternative?

• How do we educate our

customers, regulators and

legislators to their potential?

• Which customers are good

candidates for integrated DER

solutions fashioned as a

microgrid?

66

RELIABILITY & RESILIENCE FOR A KEY ONCOR

OPERATIONAL SITE

• 100-acre industrial-campus site with key operations for

meter testing, transformer testing and refurbishment,

communications, and environmental labs and compliance

• During major grid outages, site takes on 24x7 roles for

restoration and environmental management

67

Original site: 10 metered services, UPS & 3 emergency

gensets, with limited site operations during local grid outages

Project objective: single primary-metered point of service, site-

wide microgrid, adaptable to a variety of situations

ESS USES AT ONCOR’S MICROGRID

• Blackstart capability for the site

• Preserve minimum levels of state-of-charge to support the blackstart

• Demonstrate role of ESS for feeder reliability

• Time-shift energy to demonstrate

• Storage as an distribution upgrade deferral tool

• A TOU rate and energy arbitrage technical capability

• Manage site peak demand on the grid

• Future studies

• Smooth the rapid fluctuations of solar due to clouds

• Firm solar as a resource – variability due to clouds

• Power factor management for the site

68

TECHNOLOGY DEVELOPMENT & EDUCATIONAL

CENTER (TDEC)

• Create a friendly, non-technical center for conversations

about the future

• Customers

• Developers

• City leaders

• State officials

• Competitive market players

69

Microgrid

70

Oncor Microgrid Demonstration Project

Goals

• Autonomously controlled microgrid

• Multiple generation sources, both renewable and non-

renewable

• Diverse equipment from diverse suppliers to

demonstrate the integration typical of brownfield sites

• Demonstrate the ability to seamlessly combine and

switch between multiple generation sources

• Remotely control from user-friendly GUI

• Develop an Immersion Room capable of displaying the

evolution of the power grid

• Design a control room that also accommodates tour and

educational uses

71

Sequence of Operations

Oncor Confidential - For Internal Use Only72

Tesla Battery• 200 kW/ 400 kWh Stationary

Storage

• Six 70 kWh Li-Ion batteries

• Two 100 kW bidirectional

Princeton Inverter/Chargers

Specifications

• DC Capacity: 420 kWh

• Nominal AC Power: 200 kW

• Voltage Range: 288-403.5 V DC

• Nominal Voltage: 345 V DC

• Efficiency: 85%, Roundtrip

• Nominal Discharge Current (per

sub-pack) : 320 A DC

• Peak Discharge Current (per

sub-pack): 350 A DC

• Input Voltage(communications

and charging) : 3 phase 480 V

Solar Canopy and

Ground mounted PV

ArrayCanopy

• 112 kW DC

Composed of the following:

• 448 Kyocera KD F 250 W

modules

• 6 SMA Sunny Tri Powers –

480/277 V centralized inverters

• 97% Efficiency

• Large, full cantilever “tapered”

tee support structure

• South-facing – maximize energy

production

Ground Mount

• 3.5 kW DC

• Single pole mounted inverter

• Schletter FS ground mount

racking

• West-facing – output correlates

better with grid peak load times

65 kW Propane

MicroturbineSpecifications

• Output Power: 0-65 kW

• Output KVA: 65 kVA

• 30-35% efficiency

• 96000 RPM at full power

• Voltage Operating Range:

360-528 V AC

• Max Output Current: 100 A

• Short Circuit Rating: 145 A

• Power Required at Start:

6.8 kW peak, 0.014 kW/hr,

42 seconds

• Cool Down Power: 2.0 kW peak,

0.3 kWh for 90 seconds

• Standby Power: 0.8 kW

• Grid Inrush Current: 24 A

• Starting Current from Grid:

16 A

• Output Power Slew Rate:

1.15 kW/sec (900 rpm/sec)

GeneratorsTotal of 4 generators on site

supporting the micro-grid at

various locations

• Micro-grid Section 2

• Generator 2• 210 kW 480 V

• Generator 4• 45 kW 120/208 V

• Micro-grid Section 3

• Generator 3• 175 kW 120/208 V

• Generator 5• 175 kW 120/208 V

• Generator 2 and Generator 5 do

not sync correctly and therefore

cannot be paralled.

• As a result, Micro-grid sections

1 & 2 can not be tied in to

section 3 if both generator 2 & 5

are running

Transformer 16

• ABB 500 kVA , 12.47 kV/480/277

V with 480 V Delta Tertiary

• The Delta Tertiary winding has

an electrically actuated

contactor inside of the cabinet

• This contactor is used to

provide a 480 V and 12.47 kVA

ground reference when Micro-

grid Section 1 is islanded

Outline

Why Now? Cost trend for energy storage

Energy Storage System (ESS) Definition

Roles – Bulk power, wires, customer-sited and DER

Utility distribution systems & ESS

Power, energy, reactive

Delivery asset alternative, reliability, microgrid

Multiple uses of a single ESS

Regulatory & market construct considerations

78Copyright © 2017

THE OBJECTIVE – MAXIMIZE USE OF THE ASSET

• Many studies of energy storage have sought to maximize

the value of the asset by finding multiple uses

• Implementations in demonstrations and in commercial

projects also have often adopted that approach

• Uses may each draw on the energy reservoir, the immediate

power response, the reactive power capability of the power

conversion system

• Key engineering considerations are the determination of the

operating requirements for each proposed application, and

the design of a control system that will not compromise

other uses

79

GRID ENERGY STORAGE VALUES

80

BULK GRID

Wind & solar firming, smoothing and dispatch

Time-shift energy supply vs. need (eg. wind & solar) to meet market needs and/or energy arbitrage

Grid reliability services

• Supply regulation

• Frequency regulation

• Responsive reserves for grid contingency

• Fast response

DISTRIBUTION FEEDERS &

SUBSTATION

Support the local grid during upstream outages

Defer or substitute for traditional upgrades needed to support growing loads

Integrate distributed renewable sources (DERs) to the local grid to maintain grid stability & voltage control

CUSTOMER

Manage peak demand on the grid to limit demand charges

Smooth & firm customer-sited solar or wind

Time-shift energy from the grid or from customer-sited solar, such as to manage energy use under a time-of-use retail rate

Support islanded microgrid operation for critical services during grid outage

Focus of this lecture

Outline

Why Now? Cost trend for energy storage

Energy Storage System (ESS) Definition

Roles – Bulk power, wires, customer-sited and DER

Utility distribution systems & ESS

Power, energy, reactive

Delivery asset alternative, reliability, microgrid

Multiple uses of a single ESS

Regulatory & market construct considerations

81Copyright © 2017

BATTERY

TRANSMISSIONGENERATION

RETAIL ELECTRIC

PROVIDERS

DISTRIBUTION LINES

CompetitiveRegulated

ONCOR’s ROLE IN THE MARKET

Competitive ERCOT wholesale and retail electric energy market

since 2002 for investor-owned players

Regulated delivery utilities – do not generate, own, or sell electricity

Generators Transmission &

Distribution

RegulatedCompetitive

Retail Electric

Providers (REP)

Competitive

Generators Transmission &

Distribution

RegulatedCompetitive

Retail Electric

Providers (REP)

Competitive

83

Reliable delivery through the application of technology

Summary

84Copyright © 2017

LEARNINGS TO DATE

Storage is a complex technical and business consideration

Direct learning from detailed study, design, procurement,

and internal coordination is invaluable. Storage isn’t easy,

yet, for distribution feeders.

Services model: Regulation services will place challenges

on feeder voltage management and coordination, to avoid

undue wear on transformer LTC and risk of overvoltage.

Additional expense may be required.

Reliability operation: Novel blackstart with battery and

PCS present analytical challenges to assure in-rush

currents are met without damaging the ESS. Assuring

adequate fault current to operate existing protection/fuses

on the feeders is challenging.

85

EXPERIENCE WITH DISTRIBUTED STORAGE AND SOLAR

Design & specification

Siting & commissioning

Integration with system protection, SCADA, control of

traditional utility switchgear

Operational experience

• Reliability – backup to utility power

• Inverter-based systems – IEEE 1547

• Solar smoothing

• Reactive power management

86

CONTACT

Bill Muston

Oncor Electric Delivery Company LLC

bill.muston@oncor.com

214-486-3015

87

How do we reduce the length

& frequency of power

outages?

How do we increase the

efficiency of the grid?

How do we create a more

resilient, secure and even

self-healing power grid?

How do we integrate

increasing amounts of solar

and wind power into the

grid?

How do we support

customers who choose

rooftop solar and electric

vehicles?

How do we achieve all this and still

keep your monthly bill affordable?

Appendices: Glossary & References

88

Terms

SAIDI – System Average Interruption Duration Index

• Quantitative measure of the reliability of power service

• Measured in minutes/year

ESS – Energy Storage System

PCS – Power Conversion System

SCADA – Supervisory Control and Data Acquisition

BES – Bulk Electric System – definition http://www.nerc.com/pa/RAPA/BES%20DL/BES%20Definition%20Approv

ed%20by%20FERC%203-20-14.pdf

Battery Terminology Reference –

mit.edu/evt/summary_battery_specifications.pdf

89

References – Page 1

DOE Global Energy Storage Database – database of projects –

http://www.energystorageexchange.org/

Energy Storage Integration Council (ESIC), hosted by EPRI, focused on utility distribution

applications http://www.epri.com/Pages/EPRI-Energy-Storage-Integration-Council-

(ESIC).aspx

MESA – Modular Energy Storage Association – ‘Open Standards for Energy Storage’ –

http://mesastandards.org/

Sandia National Laboratory – Energy Storage Systems Program – facilitates and publishes a

variety of DOE-sponsored studies and reports related to the application of ESS –

http://www.sandia.gov/ess/

http://www.sandia.gov/ess/publication/doeepri-electricity-storage-handbook/

Lazard Levelized Cost of Energy Storage v2.0 – Examines the lifetime ownership cost for

energy storage in a variety of applications and of a variety of types of energy storage –

https://www.lazard.com/perspective/levelized-cost-of-storage-analysis-

20/?utm_content=buffer7978d&utm_medium=social&utm_source=twitter.com&utm_campaig

n=buffer

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References – Page 2

Fault Location, Isolation, and Service Restoration (FLISR)

https://www.smartgrid.gov/files/B5_draft_report-12-18-2014.pdf

Northern Power Low Carbon Network Fund Youtube Video

http://www.youtube.com/watch?v=KUGpUaA4D5k&index=1&list=UUx_iDK8VCyKqYmAkORA

hNzw

AEP Filing with PUCT on storage for specific reliability and asset deferral projects (PUCT

46368)

http://interchange.puc.texas.gov/WebApp/Interchange/application/dbapps/filings/pgControl.asp?TXT_UTILIT

Y_TYPE=A&TXT_CNTRL_NO=46368&TXT_ITEM_MATCH=1&TXT_ITEM_NO=&TXT_N_UTILITY=&TXT_N_FILE

_PARTY=&TXT_DOC_TYPE=ALL&TXT_D_FROM=&TXT_D_TO=&TXT_NEW=true

• The initial filing to open a docket:

http://interchange.puc.texas.gov/WebApp/Interchange/application/dbapps/filings/pgSearch_Results.asp?TXT_CNT

R_NO=46368&TXT_ITEM_NO=1

• The filing that described the two grid applications for deployment of energy storage in lieu of traditional utility

equipment:

http://interchange.puc.texas.gov/WebApp/Interchange/application/dbapps/filings/pgSearch_Results.asp?TXT_CNT

R_NO=46368&TXT_ITEM_NO=2 Despite this being a legal document with a regulatory agency, it contains very

readable descriptions of the two projects

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References – Page 3

Austin Energy’s DOE SHINES Project

http://www.ercot.com/content/wcm/key_documents_lists/85512/02._ETWG_Austin_SHINES.p

ptx

Pedernales Electric Cooperative DOE Project

http://www.energy-storage.news/news/ams-and-pedernales-electric-cooperative-win-us3.24-

million-energy-storage-g

Arizona Public Service ‘Solar Partners’ Energy Storage

http://www.tdworld.com/energy-storage/aps-aes-bring-energy-storage-arizona-customers

San Diego Gas & Electric Unveils Worlds Largest Lithium-Ion Energy Storage

http://www.tdworld.com/renewables/sdge-unveils-worlds-largest-lithium-ion-battery-energy-

storage-facility?NL=TDW-01&Issue=TDW-01_20170301_TDW-

01_946&sfvc4enews=42&cl=article_4_b&utm_rid=CPG04000000116581&utm_campaign=1276

3&utm_medium=email&elq2=55c63a250535471ea5d6c1a4195b2961

Oncor Confidential - For Internal Use Only92

References – Page 4

Competitively Structured Markets – See the ABACCUS report by Distributed Energy Finance

Group

• http://defgllc.com/

• http://defgllc.com/publications/consumer-choice/ Annual Baseline Assessment of Choice in the

United States and Canada

Brattle Report Examining Dual Technical Uses of Battery wherein the Users Are Utility and

Market Participants, Respectively

• Brattle Press Release – a good summary of the report

• http://www.brattle.com/news-and-knowledge/news/749

•

• Link to Full-Length Technical Report Released in 2015

• http://www.brattle.com/system/publications/pdfs/000/005/126/original/The_Value_of_Distributed_Electricity_Storage_in_Texas_-

_Proposed_Policy_for_Enabling_Grid-Integrated_Storage_Investments_Full_Technical_Report.pdf?1426377384

• Presentation

• http://www.brattle.com/system/publications/pdfs/000/005/119/original/The_Value_of_Distributed_Electrical_Energy

_Storage_in_Texas.pdf?1423513210

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ONCOR STORAGE PROJECTS

NSRI – Neighborhood Storage

Reliability Initiative

Microgrid at Oncor operational

facility

Rural Feeder Reliability – Can a

battery located on long rural feeder

support customers when the

upstream portion of a feeder is

out?

94

BRATTLE STUDY ON DISTRIBUTED STORAGE

• The Brattle Group examined the relative economics of 1000

MW to 8000 MW of distributed storage

• The system-wide (and societal) analysis shows that ~5000

MW (15,000 MWh) of distributed storage is most cost-

effective across ERCOT at $350/kWh storage cost

• System-wide benefits include:

Avoided distribution outages

Deferred distribution investment

Deferred transmission investment

Avoided new generation capacity investments

Production cost savings

• Positive payback is dependent on both regulated investment

deferral and merchant/market value of the energy

95

Homework Exercises:Thursday, March 30.

1. ESS specifications for distribution feeders depend on the applications they must serve (kVA capacity of inverter and kWh capacity of battery)

Peak Shaving (kVA and kWh requirement)

Islanding (kVA and kWh requirement)

System Protection (kVA requirement)

Background

Today, the maximum kVA of load on a feeder is 2750 kVA without overloading the substation transformer

The peak load on that feeder is projected to grow in a year from 2750 kVA to 2951 kVA

On peak load day the load is expected to go above 2750 kWh limit for 2.5 hours, as shown in the graph

The load shape is expected to be as shown in the graph, and the load will be greater than 2750 kVA for 2.5 hours

The first parts of the question will be to specify an ESS to support this increased peak load in lieu of a substation upgrade that would require a new substation transformer and bus

Assumption: assume the area of the peak load curve above the level of 2750 kVA is an isosceles triangle to simplify the calculation

Background

The next parts of the question will be, for the same feeder, specify an ESS to support the downstream half of the feeder with the ESS during an upstream outage

The outage is over the same future peak hours load curve as the prior problem

The last part of the question will be to size the ESS to support fault current for fuses serving a 3-phase load for a fault during islanded operation: A fault is assumed to occur on a feeder lateral during

islanded operation, requiring the inverter to provide fault current through the fuse on the lateral.

Additional assumptions

Assume the ESS is a perfectly efficient unit, with no losses through the inverter and no losses in the battery through charging or discharging A kWh ac is the same as a kWh dc

Assume the feeder is operating at unity (1.0) power factor

Assume the load shape during those peak hours (for the portion above 2750 kVA) is an isoceles triangle with the base being the segment along 2750 kVA

Assume the ESS performance is not affected by ambient temperature

Assume the feeder load curve is precisely halved for the A.2 problem

Questions

1. Refer to Feeder Load CurveA. What kVA capacity ESS can prevent feeder overload?B. Approximately how many kWh energy storage would be needed to

support the peaking period? C. Approximately what kVA capacity would the ESS need to be able to island

half of the feeder load during peaking time? Assume the load shape curve is precisely half for the half of the feeder to be supported by the ESS during an outage

D. How many kWh are needed? Assume the shape is a rectangle on the bottom and a triangle on the top

Refer to Fuse CurveE. A 1000 kVA 3-phase load is attached to the half of the feeder on island protected by 65 A primary fuses (12.5 kV phase-to-phase). Assume the ESS inverter can provide 150% of its continuous kVA rating for 10 seconds. Approximately what continuous kVA capacity would the ESS need to be able to operate all three fuses in under 5 seconds?

Feeder Load – 1 day

Peaking Time

5 s

Problem Statement 2Customer-Sited Storage

The commercial customer decides to install an ESS to limit its peak load, in order to reduce demand charges

The demand charge is based on the peak load over a 15-minute interval each month, and is reflected in a monthly charge on the utility bill

A. How large should the ESS be to reduce the demand incurred in the three hourly blocks of time of 14:00 thru 16:00 blocks to the level shown for the 08:00 thru 13:00 hour blocks?

B. What does the discharge and recharge profile look like, if a slow recharge is conducted over hours not being discharged?

Utility Customer

M

Meter• kWh – Total each 15-minute interval

• kW – Demand

• Time stamp

Load

Commercial Customer

Utility Customer Adds Storage

Load

ESSM

Customer Load Profile

Hour kW load

0 100

1 100

2 100

3 100

4 100

5 100

6 100

7 175

8 300

9 300

10 300

11 300

12 300

13 300

14 400

15 400

16 400

17 300

18 300

19 250

20 100

21 100

22 100

23 100

0 100

Description

The load profile is shown numerically at rightHour 0 = midnight

For simplicity, assume the load increases instantaneously at the start of the hour and continues at the level for the full hour

Assume this load profile is the same for all work days, M-F

Assume this load is not sensitive to weather changes

Demand Charge Mgt

Differential demand at peak = peak hours kW less mid-level demand = ESS kW capability

Peak duration is over the peak hour shown above

Energy in ESS needed = ESS kW x hours of discharge

Recharge Rate 24 hours less the hours being discharged