Challenges in linking different storage technologies: Combining batteries and SMES for improved performance of energy storage

Antonio MorandiDEI − Guglielmo Marconi Dep. of Electrical, Electronic and Information Engineering

University of Bologna, Italy

Workshop on Hybrid Energy and Energy Storage Systems

14 November 2018, Bruxelles, Belgium

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• SMES – who they are and state of development

• Hybrid SMES / Battery Energy Storage

• Motivations

• Case studies

• Fast Charging Stations

• Wind

• Solar

Outline

PCS

Control and protection system

Cooling system

Superconducting coil

grid

Current leads

vacuum vessel

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SMES – Superconducting Magnetic Energy Storage

2

0

2

0

2

21

22ILdBdBW

coil

=≈= ∫∫∞ ττ

τµ

τµ

Advantages• High deliverable power • Infinite number of charge

discharge cycles• High efficiency of the charge

and discharge phase (round trip)

• Fast response time from stand-by to full power

• No safety hazard

Critical aspects• Low storage capacity• Need for high auxiliary power (cooling)• Stand-by losses

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• Flexible architecture - Control algorithm defined based on the service to be provided • Power modulation (grid/load decoupling)• Islanding operation (UPS)• Active filtering

• Magnet protection system integrated in the PCS both at HD and the SW level

Power Conditioning System - detail

System level control P*, Q*, i*, v*

DC/AC - inverter DC/DC - chopper

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To know on SMES – 1 / Energy capacity

Typical rating of SMES in the order of MJs (MW × seconds)

• Energy: MJs → kWs

32 cm

1.2 kWh Commercial Li-battery module

Energy capacity of large SMES comparable with that of small battery systems

• Power: MWs

1 MW Li-battery system (groupnire.com)

Power capacity of SMES comparable with that of large battery systems

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To know on SMES – 2 / Standby lossesCurrent of SMES free-wheels through PE switches when no power is delivered/absorbed. Losses are produced during the standby

Von IGBT = 0.5 − 1.5 VVon DIODE = 0.5 − 1 V

PIGBT = ISMES Von IGBT PDIODE = ISMES Von DIODE

Pidling = 1 − 5 kW / kA

SMES currentdelivered power L C

Vdc

ISMESDC /

AC

SMES

• The whole energy of the SMES is lost in the power electronics within a few minutes

• SMES is only suitable for continuous operation

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To know on SMES – 3 / Efficiency

cs

tPtP

ηη

η∆∆

=

P, deliverable power ∆t , duration of delivery ∆ tcycle , duration of the cycle∆ tidle, duration of idling phaseηs , intrinsic efficiency of the storage device ηc , efficiency of the convertersPaux , power required for auxiliary services Pidle , power loss (if any) during idling

cycle

power

energy

idleidlecs

tPtPtP

∆+∆

∆=

ηη

η

aux cycle idle idles c

P tP t P t P t

η

η η

∆=

∆+ ∆ + ∆

High efficiency of SMES achieved in case• High exchanged power• No (or short) stand-by / continuous power

management(additional services can mitigate this)

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Japan

Germany

EM Laucher

Japan

USA

Japan

Italy

France

Germany

Power modulatorFlicker

Grid compensation

The state of the art of SMES technology

The DRYSMES4GRID project:• 500 kJ / 200 kW SMES• MgB2 material• Cryogen free cooling

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• SMES – who they are and state of development

• Hybrid SMES / Battery Energy Storage

• Motivations

• Case studies

• Fast Charging Stations

• Wind

• Solar

Outline

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Which storage technology?

Parameters of the energy storage system • Absorbed/supplied power, P• Duration delivery, ∆t• Number of cycles, N• Response time, tr

No unique storage technology exists able to span the wide range of characteristics required for applications

• Most suitable storage technology must be chosen from case to case

• Hybrid systems, obtained by combining Energy Intensive Storage (EIS) with Power Intensive Storage (PIS), can be the best solution in many cases

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Combined use of synergistic technologies

A 350kW/2.5MWh Liquid Air Energy Storage (LAES) pilot plant was completed and tied to grid during 2011-2014 in England.

Fundraising for further development is in progress

• LAES is used as energy intensive storage • Large cooling power (not all) is available for SMES

due to the presence of Liquid air at 70 K• SMES is used as power intensive storage

Effective hybrid (Energy intensive + Power intensive) storage can be conceived based on combined use of SMES and LAES

A 1-2 MW / 2-5 min rating for SMES may be of interest.Demanding !!!

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Hybrid energy storage systems – Motivations

DC/DCBattery

Grid Load

DC/DCSMES

DC/ACLow-pass Control

High-pass ControlSy

stem

Cont

rol

Operation• High frequency components of the power spectra are

assigned to SMES by means of a high pass control • Low frequency components are left to battery

time, auQualitative (not a real case)

Complementary characteristics exploited

• Battery provides long term base power – hence energy

• SMES provides peak power and fast cycling

Advantages:

• Reduced power rating of batteries • Reduced energy rating of SMES • Reduced wear and tear of

batteries (no minor cycling)

Pmax = 0.38

Pmax = 0.62

Emax = 1

Emax = 0.18

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• SMES – who they are and state of development

• Hybrid SMES / Battery Energy Storage

• Motivations

• Case studies

• Fast Charging Stations

• Wind

• Solar

Outline

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BESS

DC

DC

DC

DC

SMES

DC

DC

DC/DC

DC/DC

DC/DC

DC/DC

DC/DC

DC/DC

DC/DC

DC/DC

Slot 1

Slot 2

Slot 3

Slot 4

Slot 5

Slot 6

Slot 7

Slot 8

Charging SlotsHybrid Battery-SMES ESS

PV power plant

Case study – A PV powered fast charging station DC

AC

Grid

Objective: minimizing exchange with the grid - Pgrid ≤ 100 kW

Simplifying assumption: the system operates off grid - Pgrid = 0

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Load profile of the FCS – Assumptions:

Max 8 × 25 kWh vehicles recharging at 5CMax power of each slot: 125 kWMax total power: 1000 kW

time, s

Total delivered power, kWTotal delivered energy, kWh

Load profile of the FCS obtained from estimated quick charging needs – Aalto University, Finland

Data adapted from F. H. Malik and M. Lehtonen, "Minimization of queuing time of electric vehicles at a fast charging station," 2017 IEEE PES Innovative Smart Grid Technologies Conference Europe (ISGT-Europe), Torino, 2017, pp. 1-6

Total energy delivered by the FCS in one day: 7.3 MWh

time, s

Production of the PV plant - Assumptions:

The PV produce in one day all the energy required by the FCS

17time, s

Total power produced by the PV plant, kW

time, s

Total energy produced by the PV plant, kWh

Total energy produced by the PV plant in one day: 7.3 MWh

Data adapted from the measured production of a real PV plant

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Energy and power rating of the EES

Power delivered/adsorber by the EES is obtained by difference:

PEES = Pslots – PPV

time, s

Total Power of the EES, kW

time, s

Total energy of the EES, kWh

An initial charge at 0,6 MWh is assumed for the EES in order to avoid discharge below 20 % of SOC max

Peak Power = ± 800 kW

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time, s

Total Power of the EES, kW

time, s

Total energy of the EES, kWh

• The energy rating of the ESS is (about) 2.2 MWh

• The max power rating of the ESS is (about) ± 800 KW

A 2.2 MWh EES operating at a maximum rate of C3 fulfils the requirements . This performance can be reached with batteries.

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Is there a role for SMES?

Low pass control

High pass control

Note: no claim is made to elaborate an optimized control strategy

( Is there an adavantage for hybridization )?

Battery

SMES

total

time, s

Power of the EES componets, kW

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Battery

SMES

total

time, s

Power of the EES components, kW

Battery

SMES

total

time, s

Power of the EES components, kW

Power RatingTotal 800 kW input 800 kW output

Battery 460 kW input 320 kW output

SMES 680 kW input 520 kW output

Energy RatingTotal 2200 kWh

Battery 2200 kWh

SMES 680 kWh

• Power rating of batteries reduced by nearly 50 %

• Energy rating (and minor cycling) of battery substantially unchanged

• Energy rating of SMES less than 20 % of batteries – still demanding!

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Miller, GE Experience with Turbine Integrated BES, PES 2014

Controlling wind power

Area wide AGC is emitted on 5 minutes base based on frequency deviation

Predictable wind Powerdemonstrated

200 kWh of batteries GE 1.6 MW – 100 m

Demonstrated- GE @Tehachapi - 2012

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Energy/power rating for wind control

A case study –Controlling a 20 MW Wind power plant

0 1000 2000 3000

time, seconds

59.95

60

60.05

frequ

ency

, Hz

∆f = ± 12 mHz∆P = ± 10 %

time, s

Power of the wind plant, MW

dispached

produced

Power of the storage, MW

time, s

Measured grid frequency, July 7 2016

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Battery

SMES

total

time, s

Power of the EES components, MW

Battery

SMES

total

time, s

Power of the EES components, kW

Power profile non suitable to be split in a low frequency + high frequency component

• Power rating of battery little affected …..

Controlling Solar Power

A case study – Controlling a 285 MW solar power plant with a 85 MW EES

Solar Power

Energy shifted at sunset“Duck Curve” Smoothing

… of very high value for power system

Delivered Power

Power profile suitable for hybridization

EES Power

SMES 6 MWh

Qualitatively …..

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DTT - Divertor Tokamak Test Facility

150 MW × 80 s (1.2 GJ) –1 per hour

Research facilities with pulsed power

Industry ± 1-10 MW × 20 min – continuous

More cases with reduced size should be looked for in industry (press, rolling mills, punchers …)

0 5 10 15 20 25 30

time, mimutes

0

10

20

30

40

50

pow

er, M

W

Railway substation± 20 MW × 3 min – continuous

JapanSource 10.1109/TASC.2005.849333

A note: more case studies for application of power intensive and/or hybrid storage can be looked for in industry

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Question 1: Does a power profile suitable to be split in a "high power / low energy" and a "high energy / reduced power" component exist in the real world? What can be a case study?

Question 2: Is there a power intensive storage technology able to bring a substantial - not marginal - benefits to batteries? Can SMES succeed in this?

…. finally

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30

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• Stephentown, NY, since 2011

• HazleTownship, PE, since 2014

Flywheels perform between 3,000 and 5,000 full depth-of-discharge cycles a year.

Beacon power ±20 MW frequency regulation plant

~7’ tall, 3’ in diameter 2,500 pound rotor mass Spins up to 15,500 rpm 100 kW, 25 KWh (charge and discharge)

110 m

130 m

20 × 10 × 0.1 kW fly-wheel units

No loss data available

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110 m

130 m

±20 MW frequency regulation plant based on SMES

110 m

130 m8 T

Operating field 8 TToroidal diameter (outer) 70 mPoloidal diameter 2 m

3 T

Operating field 3 T2 × 100 m × 50 m loopsTransverse diameter 2 m

qualitativeSource: civicsolar.com

±20 MW frequency regulation plant feasible also based on SMES

No battery technology can be used for copying with 60000 cycles (20 years) unless very substantial overrating is applied

60000 cycles possible at 5 % DOD400 MW rating needed!!!!!

0 1000 2000 3000

time, seconds

59.95

60

60.05

frequ

ency

, Hz

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Miller, GE Experience with Turbine Integrated BES, PES 2013

Controlling wind power

100 % P 90 % P 80 % P

• AGC is emitted on 5 minutes base based on frequency deviation

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Possible Hybrid systems

ENERGY INTENSIVEPOWER INTENSIVE

Sc, smes o fw + batterie

Batt + thermal o caes

Smes + LAES o LH2 (sinerg)

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1. A 200 kJ Nb-Ti µSMES ( 2000 – 2004 )

Cold test in 2004 (and 2013)

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2. Conduction cooled MgB2 SMES demonstrator (2014 – 2016)

• 3 kJ MgB2 Magnet• 40 KW Mosfet Based PCS

Cold test completedFull test at 1-10 kW to come shortly

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• Transmission and distribution• Dispersed generation, active networks and storage• Renewables (PV and Biomass )• Energy efficiency in the civil, industry and tertiary sectors• Exploitation of Solar and ambient heat for air conditioning

MISE - Italian Ministry of Economic DevelopmentCompetitive call: research project for electric power grid

The DRYSMES4GRID Project

Partners • University of Bologna• ICAS - The Italian Consortium for ASC, Frascati (Rome)• RSE S.p.A - Ricerca sul Sistema Energetico, Milan• CNR – SPIN, Genoa

Project DRYSMES4GRID funded

• Budget: 2.7 M€• Time: June 2017 – June 2020

Project Coordinator:• Columbus Superconductors SpA, Genova, Italy

• developm. of dry-cooled SMES based on MgB2• 300 kJ – 100 kW / full system

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