application of battery energy storage for frequency … switzerland ltd, corporate research - 7 ∆t...

Application of Battery Energy Storage for Frequency Regulation

Alexandre Oudalov

IEEE PES Swiss Chapter Workshop, Daettwil, 9.11.2006

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Agenda

� Energy storage technologies and applications

� Primary frequency control and ancillary service markets

� Dimensioning of the BESS for primary frequency control

� Conclusions

� Q&A

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Energy storage technologies

Excessive electricity is stored at times of low demand, then the energy is retrieved when demand peaks

Energy Storage

Electrochemical

Electrical

Mechanical

Thermal

Power Systemelectric energyproduction and consumption

Low demand

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Energy Storage

Electrochemical

Electrical

Mechanical

Thermal


Peak demand

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Energy Storage

Electrochemical

Electrical

Mechanical

Thermal


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� Pumped-Hydro Storage (PHS)

� Battery Energy Storage Systems (BESS):

■ Lead Acid

■ Nickel-Cadmium

■ Nickel-Metalhydride: too expensive

■ Sodium-Sulfur

■ Lithium-Ion: too expensive

■ Vanadium Redox flow

■ Polysulfide-bromine flow (project stopped)

� Superconducting Magnetic Energy Storage: too

expensive

� Electrochemical Capacitors: too expensive

� Flywheels: too expensive

� Hydrogen technology: not yet mature

� Thermo electric energy storage: not yet mature

� Compressed Air Energy Storage: needs fuel, site

dependent



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∆T

BESSIntegration of

renewables1-100 MW, 1-10 h

BESS

Peak

shaving 0.1-10 MW, 1-2 h

20 kV 110 kV

220 kV

110 kV20 kVNetwork ring

20 kV

Industry

Centralgeneration

Distributedgeneration

220 kV Overhead line

Weak connection

BESSLoad leveling

for postponement of

grid upgrade

10-100 MW, 1-4 h

Load levelingfor generation

utilization

10-100 MW, 1-4h

BESS

to Load

BESS

Frequency control1-20 MW, 0.5-2 h

Applications of BESS in power systems

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not profitable

in a few, very special cases

only

might be profitable

probably profitable

out of question

Load leveling for generation utilization (large scale arbitrage)

End-user Peak shaving

Load leveling for postponement of T&D upgrade

Primary Frequency Regulation in the today’s market

Integration of renewables (in island grid)

Applic

ations

Will a BESS for that specific application alone be a profitable solution?

Applications of BESS in power systems

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BESS for frequency control - Roadmap

2006

AEP NaS, USA

2003

GVEA Ni-Cd, USA

1988

CHINO Lead-Acid, USA TEPCO NaS, Japan

1998 20011986

BEWAG Lead-Acid, Germany

1994

PREPA Lead-Acid,Puerto Rico

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0

BESS in Golden Valley Electric Association

In operation since 2003

System Supplier:

� ABB in cooperation with SAFT (Ni-Cd battery cells) � Cost: 35 million US$

Specification:

� 40 MW for 7 min (4.7 MWh)� 27 MW for 15 min (6.75 MWh)� AC to AC efficiency ≈ 75%

Applications:

� Backup power in case of line loss� Reactive power support

ConverterNi-Cd Batteries

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Existing 100 MW Transmission line

NorthernIntertie140 MW

Healy

Fairbanks

BESS

BESS in Golden Valley Electric Association

In operation since 2003

System Supplier:

� ABB in cooperation with SAFT (Ni-Cd battery cells) � Cost: 35 million US$

Specification:

� 40 MW for 7 min (4.7 MWh)� 27 MW for 15 min (6.75 MWh)� AC to AC efficiency ≈ 75%

Applications:

� Backup power in case of line loss� Reactive power support

ConverterNi-Cd Batteries

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Frequency control reserves

operating dead-band

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out

in

Power System

f f

Pt

INJECT POWER

ABSORB POWER

BESS operating principle for frequency control

BESS

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Fre

quency

pri

mary

reserv

e r

equir

ed (

MW

)

Bidding process per kW €20

€30

€40

€50

€60

€20

€30

€40

€50

€60

€70

Period 1 Period 2 Period 3

€20

€30

€40

€50

€60

€70

BESS

€60 €70 €60

Primary frequency control market mechanism

Tendering period:

Germany 6 months

Czech Rep. 1 week

New Zealand 1 day

Forecasted need

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Cost of primary control reserve in Germany

Source: http://www.eon-netz.com/http://www.vattenfall.de/http://www.rwe-transportnetzstrom.com/http://www.enbw.com

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UCTE measured frequency April 2005

© 2005 ETRANS

5 10 15 20 25 3049.8

49.85

49.9

49.95

50

50.05

50.1

50.15

50.2

Measure

dfr

equency

[Hz]

Time [Day]

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Frequency statistics April 2005

<-0.2 -.2 - -.14 -.14 - -.1 -.1 - -.06 -.06 - -.02 -.02 - 0 0 - .02 .02 - .06 .06 - .1 .1 - .14 .14 - .2 >.20

5

10

15

20

25

30

35

40

45

50R

ela

tive t

ime p

eri

od [

%]

Frequency deviations (intervals) [Hz]

35.6% 31.8%

16.1% 15.2%

0.5% 0.8%

Frequency deviation intervals [ Hz ]

Re

lati

ve

tim

e p

eri

od

[%

]

67.4%}

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20

Battery charge

Battery discharge

Regulation characteristic

-1.5

-1

-0.5

0

0.5

1

1.5

-300 -200 -100 0 100 200 300

Frequency deviation from 50Hz [mHz]

Pri

ma

ry r

ese

rve

activa

tion

[p

.u.]

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BESS primary control power April 2005

5 10 15 20 25 30-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

BE

SS

Pow

er

[Pn]

Time [Day]

Battery charge

Battery discharge

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5 10 15 20 25 30-1.6

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

Sta

te o

f D

ischarg

e [

Pn*h

]

Time [d]

Minimum Battery Capacity = 1.62 Pn*h

Time [ day ]

“A

bs

olu

te d

ep

ths

of

dis

ch

arg

e”

[ P

nx

h ]

BESS efficiency 0.7 with no recharge April 2005

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Assumption for modeling

� Frequency deviation can not be predicted !

� BESS =! 100% availability

� Battery should never be empty ! (try to keep battery charged using a small recharge power when ∆f < | 20mHz |)

� For any case keep an additional reserve capacity of 15min x Pn

� In case battery is full, absorb power with resistors

� BESS = Battery (Pn, Pn*h) + Resistors (PR= Pn)

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5 10 15 20 25 30-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1S

tate

of

Dis

charg

e [

Pn*h

]

Time [d]Time [ day ]

“A

bs

olu

te d

ep

ths

of

dis

ch

arg

e”

[ P

nx

h ]

April 2005

BESS efficiency 0.7 recharge with 1% of Pn

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5 10 15 20 25 30

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

Pow

er:

pure

Batt

ery

pow

er

(red)

and r

esis

tor

(blu

e)[

Pn]

Time [d]

Energy loss in resistors = 2.74 Pn*h

Time [ day ]

0.6

0

-0.6

BE

SS

po

wer

[ P

n]

April 2005

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5 10 15 20 25 30

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1S

tate

of

Dis

ch

arg

e [

Pn*h

]

Time [d]



Time [ day ]

“A

bs

olu

te d

ep

ths

of

dis

ch

arg

e”

[ P

nx

h ]

April 2005

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5 10 15 20 25 30

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

Pow

er:

pure

Batt

ery

pow

er

(red)

and r

esis

tor

(blu

e)[

Pn]

Time [d]

Energy loss in resistors = 6.69 Pn*h

Time [ day ]

0.6

0

-0.6

BE

SS

po

wer

[ P

n]


April 2005

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5 10 15 20 25 30-1.6

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

Time [d]

Sta

te o

f D

ischarg

e [

Pn*h

]

Time [ day ]

“A

bs

olu

te d

ep

ths

of

dis

ch

arg

e”

[ P

nx

h ]

No recharge

1%

3%

5%

BESS efficiency 0.7 recharge with 0-5% of Pn

April 2005

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� Absorb positive peaks by charging battery, as long as battery is not full

� Provide negative peaks by discharging battery

� Define range of preferred state of charge with an upper and lower level

� In case battery state of charge exceeds pre-defined upper level

� Sell small portion of the stored energy (ex. 0.02*Pn for 1h) in order to bring back state of charge to preferred operating range

� In case battery state of charge falls below pre-defined lower level

� Recharge battery to the pre-defined state of charge lower level when ∆f < | 20mHz |

� Use minimal recharge power (ex. 3% of Pn)

Assumptions for modeling

5 10 15 20 25 30

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

Sta

te o

f D

isch

arg

e [

Pn*h

]


De

pth

s o

f d

isc

ha

rge

[

Pn

x h

]

Upper level

Lower level

What is the optimal capacity and what are the optimal upper and lower state

of charge levels

? ?

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0.55

0.76

0.5560.564

0.571

0.579

0.586

0.594

0.601

0.609

0.616

0.624

0.631

0.639

0.646

0.654

0.661

0.6690.676

0.6840.691

0.699

0 0.02 0.04 0.06 0.08 0.1 0.120

0.02

0.04

0.06

0.08

0.1

0.12

SoC upper level [ Pn*h ]

Sell P

ow

er

[%

Pn]

� Input

� Max. Power (contracted primary reserve)

� Frequency profile

� Regulation characteristic

� BESS efficiency, life cycle and cost function

� Recharge tariff and

� Sell power tariff (intraday market)

� Reserve price

� Variables

� Upper and lower state of charge level

� Recharge power % of Pn

� Sell power % of Pn

� Output

� Required capacity

� Volume of sold and recharged energy

� Volume of lost energy through resistors

� Max(NPVprofit = NPVrevenue – NPVcost)

Objective: maximized NPV of profit

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Battery state of charge April 2005

Sell power 0.03 Pn

Recharge power 0.03 Pn

5 10 15 20 25 30

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1S

tate

of

Dis

ch

arg

e [

Pn*h

]


De

pth

s o

f d

isc

ha

rge

[

Pn

x h

]

100%

0%

92%

73%

52%

35%

19%

Sta

te o

f c

ha

rge

SoCmax

SoCmin

�� Required Capacity: 0.62 Pn x h

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5 10 15 20 25 30-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1P

ow

er:

pu

re B

att

ery

pow

er

(re

d)

and r

esis

tor

(blu

e)[

Pn]


BE

SS

po

wer

[ P

n]

Primary reserve power curve April 2005

BESS power (contracted reserve) 2 MWRecharged energy 8.2 MWhSold energy 3 MWhEnergy absorbed by resistors 1.6 MWh

5 10 15 20 25 30

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

Pow

er:

pure

Batt

ery

pow

er

(red)

and r

esis

tor

(blu

e)[

Pn]

Time [d]

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18.8 19 19.2 19.4 19.6 19.8-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

Pow

er: p

ure

Battery

pow

er (r

ed)

and r

esis

tor

(blu

e)[P

n]

Time [d]

De

pth

s o

f d

isc

ha

rge

[ P

nx

h ]

Time [ day ]

18.8 19 19.2 19.4 19.6 19.8

-0.2

-0.15

-0.1

-0.05

0

BE

SS

po

we

r [

Pn

]

Absorbed by resistor

Sold energy

Bought energy

Supplied by battery

100%

92%

73%

Sta

te o

f c

ha

rge

Absorbed by battery

Example: April 18-19, 2005

49.9

49.95

50

50.05

50.1

Mea

sure

d f

requ

en

cy [

Hz]

Fre

qu

en

cy [

Hz ]

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Multi-string BESS operation

Energy

Market

AS

Market

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Batteries building

PCS + control

container

MV transformerMV OHL

Space requirement for the 2 MW Lead-acid BESS

BESS surface: 14.2 x 12.9 m (184m2)

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Summary

� BESS satisfy technical requirements for frequency regulation

� BESS can be a profitable solution for providing a primary reserve

� ABB is a supplier of large battery energy storage systems

� Modeling of a BESS

� Prototype construction and extended field tests

� Construction and commissioning of the system (ex. NiCd BESS Alaska)

ABB Switzerland Ltd, Corporate Research - 35

Th

an

k y

ou

!

ABB Switzerland Ltd, Corporate Research - 36

application of battery energy storage for frequency … switzerland ltd, corporate research - 7 ∆t...

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