EnStorage_Scaps

8/9/2019 EnStorage_Scaps

1/43

1

Energy Storage by Means of Supercapacitors:Components, Power Electronics Interfaces

and Applications

Dr. P. Barrade

Laboratoire dElectronique Industrielle

EPFL - STI ISE - LEIELD 136, Station 11

Ch-1015 Lausanne / Switzerland

Phone : +41 (0)21 693 2651

Fax : +41 (0)21 693 2600

[email protected]

Seminar on Supercapacitors

Dr. P. Barrade

Summary

Generalities on Supercapacitors Principle, technology and construction

Electric-based model

Sizing of a supercapacitive tank

Energy requirements, Power availability

Thermal considerations

Limitations

Power electronics converters

Voltage equalization, Power electronics interfaces

Applications for supercapacitors

energy storage/energy buffer

elevators

hybrid vehicle

tramways/trolley-buses

UPS applications

Aeronautic application

Conclusion


2/43

2


Dr. P. Barrade

Generalities on Supercapacitors

Energy storage devices

Capacitors Dielectric (Film-Foil, Metallized film) Electrostatic

Oxide electrolytic (Al, ta) Electrostatic

Electrochemical capacitor

Pseudocapacitor Faradaic

Double layer capacitor (ECDL) Electrostatic

Battery

Pb

NiCa NiMH

Li+ Faradaic

Fuel cell

H2, Methanol (reforming) Energy conversion

Flywheel Mechanical

Superconducting Magnetic Energy Storage (SMES) Magnetic


Dr. P. Barrade


Ragone diagram : Energy Density versus Power Density


Courtesy from Montena Component SA


3/43

3


Dr. P. Barrade



Energy density


Dr. P. Barrade

Principle, Technology and Construction


+++++++

-------

-------

+++++++

1 - 3 V

2 - 10

discharged

charged

Dielectric Electrolyte Separator

Electrodes

Current Collectors

C = r A/d

W = 1/2 CU2

A : up to 3000 m2(porous film)D : fix, ~10 er: fix, ~10U : 1 - 3 V, electrolyte decomposition voltageR : low, electrolyte

Conventional capacitor ELCD capacitor


-+

-+

-+

-+

-+

-+

-+

-+

-+-+

-+-+

-+

-+

-+

-+

-+

-+

-+

-+

-+

-+

-+

-+

-+-+

-+

-+

-+

-+

-+

-+

-+

-+

-+-+

-+-+

-+

-+

-+

-+

-+

-+

-+

-+

-+

-+

-+

-+

-+

-+

+-


4/43

4


Dr. P. Barrade



Materials : Electrolyte :

"Acqueous : high ionic conductance, high power density (1V, 1.2S*cm) KOH, H2SO4

"Organic : high voltage, high energy density (2.5-3V, 50mS*cm) (Ex : 40mS*cm)

Electrode"Carbon: activated carbon

Separator"Organic: polymer (ex : 25m microporous polyolefin), paper

"Inorganic: glas fibers, ceramics

Current collector"Metal foil (Al, Ti, Fe)



Dr. P. Barrade


Construction




5/43

5


Dr. P. Barrade


Main properties

Life time : ageing mechanisms Type of aging

"Electrical solicitations

"Environmental (temperature, corrosive atmosphere)

"Mechanical (vibrations, shocks)

Electrical aging mechanisms"Ionic saturation of electrode surface

"Increased contact resistance in the electrodes

"Water diffusion

"

Impurities redox reaction"

Electrolyte decomposition

Life time : long life time thanks to

Reversible physical electrostatic charging cycles

No chemical redox reactions unlike batteries

Low voltage solicitation



Dr. P. Barrade


Main properties

Cell behaviour under crushing conditions:

Strong resistance for axial crushing

Weak resistance for transverse crushing

Temperature / fire

Opening of cells in 6 min (600C without fire)

Opening of cells in 4 min in case of direct fire exposure

Flammable gaz emission in case of opening celle if T>500C

gaz emission in case of opening (HCn)

90 cells 3000F / for a 2m3 closed volume: risk of death



6/43

6


Dr. P. Barrade


Supercapacitors today:

Maximum voltage : 2.7V

1 Million charge/discharge cycles

~0.01Euro/F

From few farads to few thousand farads

From the single component to the modules

Courtesy from Maxwell Technologies SA


Dr. P. Barrade


Modelling supercapacitors :

The main parameters of a supercapacitor (from the power electronicians pointof view) :

The energy that can be stored :"

Capacitance : from 1F to 3000F (and more !)

"Maximum voltage : typically 2.5V -> 2.7V (and more ?)

The energy efficiency :"

Series resistor : limitation of the charging/discharging current

The self discharge"Leakage resistor : self discharging of the component

The classical model for a capacitor contains

an ideal capacitor

a series resistor

a leakage resistor


7/43

7


Dr. P. Barrade



The main parameters of a supercapacitor : an ideal capacitor

"Defined by the surface of electrodes, width on ions

a series resistor"

Defined by the quality of carbon deposition on the aluminium current collectors

"Defined by the electrical conductivity of the carbon

"Defined by the ionic mobility of the electrolyte

a leakage resistor"

Overcharge beyond the decomposition limit of the electrolyte

"

Impurities redox reaction

"Redox reaction of functional groups on the edge of carbon particles

"Electronic conductance through the separator


Dr. P. Barrade



Capacitance and series resistance (ESR) Example of the BCAP0010 (Montena Component SA)



8/43

8


Dr. P. Barrade



Additional parameters (specificity of supercapacitors)

Non-constant capacitance and relaxation phenomena

Voltage dependant capacitance Relaxation phenomena are not leakage


Dr. P. Barrade




Voltage dependant capacitance (due to the width of the double layer)

How to consider?"Current capacitance

"Energetic capacitance

C =Co+Ku

Cu

!

Q =Cu! ic =

dQ

dt! i

c = C

o+ 2Ku( )Ci

! "# $#

du

dt

P = icu = C

o+ Ku( )u

du

dt!W

c=1

2C

o+4

3Ku

"

#$

%

&'

Cw

! "# $#

u2


9/43

9


Dr. P. Barrade




Voltage dependant capacitance. Example of the BCAP0008 (MontenaComponent SA) : C=1800F, Co=1800F and K=150F/V, U=2.5V

Really difficult to identify clearly the energy stored in a cell, depending ondefinitions

"Only real possibility: measures!

C 1800F 5625J

Co+K*u 2175F 6796J +20.8%

Ci 2550F 7968J +41.6%

Cv 2300F 7187J +27.7%


Dr. P. Barrade




Relaxation phenomena

"Due to porosity of electrodes (misopores, mesopores, macropores)

"During a fast charge (discharge), ions will first enter (leave) into macropores,then in mesopores

"

Diffusion of ions in misopores is characterized by long constant times

"During ageing process, relaxation phenomena is re-inforced by impuritiesaffecting the dimension of the pores

"After a fast charge (discharge), non homogeneous repartition of loads on theelectrodes

"Diffusion of the loads to reach a homogenous distribution (depends on size ofthe pores and size of the ions)

Voltage decrease (after charge)

Voltage increase (after discharge)


10/43

10


Dr. P. Barrade




Voltage dependent capacitance Cu(width variation of the double layers)

rc sub-circuits (relaxation phenomena, poreousity of electrodes)


Dr. P. Barrade

The energy stored in one single component is generally not sufficient


For a given application, it must be found :

the number of needed supercapacitors

for that number, it must be defined the arrangement for the supercapacitors :"

how many supercapacitors will be series connected in an elementary branch

" the number of elementary branches

The two last parameters define the maximum voltage and current that a

supercapacitors tank can provide


11/43

11


Dr. P. Barrade

To identify the number of supercapacitors, energy requirements have to be known.

In various applications, energy requirements are not defined.

Power requirements are often described : this is the instantaneous power that thesupercapacitors bank has to store/provide.


Energy requirements have to be identified thanks to the instantaneous

power requirements

The needed energy can be obtained thanks to the link equation between theenergy Wcand the power Pc:

Wc =

Z Pcdt


Dr. P. Barrade

Identifying the needed energy :

example


For a given power profile,

it is easy to identify by

numerical calculation theassociated energy profile.

The value of energy that

must be retained is not the

value at the end of a

complete cycle, but the

maximum value reached

during the cycle (220kJ in

the example).


12/43

12


Dr. P. Barrade

Sizing of a supercapacitors bank

From the needed energy to the number of supercapacitors : the total amount of energy in a supercapacitor is defined by the equation :

External behaviour and environment

To use to total stored energy :

the voltage across the component should be decreased from its maximum allowedvalue U

Mto 0V. But that is not possible :

" Because of the maximum current a supercapacitor can provide

" During a discharge with a constant current, the power follows the voltage profile

It is not possible to use the total amount of energy stored into a supercapacitor : a

residual voltage has to be taken into account to consider that the component is

discharged

Wc =1

2CUc

2


Dr. P. Barrade


Energy requirements Energy stored in a supercapacitor

Voltage discharge ratio: the minimum voltage during the discharge has to belimited for efficiency reasons

The usable energy is then only part ofthe maximum stored energy

Number of supercapacitors for a givenusable energy

WM =1

2CUM

2

d = 100

Um

UM

Wu = WM

1

d2

1002

Ns =2 u

CUM2

1

d2

1002


13/43

13


Dr. P. Barrade


Energy requirements

Using a 2600F/2.7V/0.4m#supercapacitor

Example: 220kJ to store

2600F, 2.5VTotal stored

energy

d=50% N=31 W=293.8kJ

d=60%

N=37 W=350.6kJ

d=70%

N=46 W=438kJ

Ns =2Wu

CUM2

1

d2

1002


Dr. P. Barrade


Power availability

Due to the series resistor of supercapacitors, energy efficiency ofsupercapacitors has to be taken into account during the sizing of thesupercapacitive tank

Energy efficiency has an influence on the power availability

Must be identified


14/43

14


Dr. P. Barrade


Procedure for the Exponential Charge

Initial charge : uci=UM.di/100

Charging voltage: Ue=UM.

Charge is finished when: ucf=UM.df/100

Main equations:

c = UM

1

1

di

100

e

t

RsC

Tch = RsCln

100 df

100 di


Dr. P. Barrade



Power in the series resistors

Energy lost in the series resistors

Taking into account Tch

Energy stored in the supercapacitor

Pr =1

Rs

UM uc

2= Pr =

1

RsUM

2

1

di

100

2e

t

RsC

Wr =Z t0

Prdt = Wr = 12CUM2

1 di

100

21 e2t

RsC

Wr = 1

2CUM

2

1

100

2df(200 df) di(200 di)

Wc =1

2Cucf

2

1

2Cuci

2= Wc =

1

2CUM

2

"df

100

2

di

100

2#


15/43

15


Dr. P. Barrade



Efficiency

For a high efficiency

dfand dimust be as high as possible

Not compatible with a large range of voltage variation

"It is mandatory to strictly control the charging/discharging current

= Wc

Wc+ Wr= =

1

200(df+ di)


Dr. P. Barrade


Efficiency for the charge/discharge with controlled current

Main equation

Charge/discharge time

Energy lost

Energy stored/provided

uc = UMdi

100+

1

C

Icct

Tch = CUM

Icc

df di

100

Wr = RsCIccUMdf di

100

Wc =1

2CUM

2

"df

100

2

di

100

2#

c = UMdi

100+

1

C

Icdt

Tch = CUM

Icd

f i

100

Wr = RsCIcdUMdf di

100

ChargeIcc>0 and df>di

DischargeIcd


16/43

16


Dr. P. Barrade


Efficiency for the charge/discharge with controlled current

Efficiency

ChargeIcc>0 and df>di

DischargeIcd


17/43

17


Dr. P. Barrade


Energy efficiency and power availability

Using a 2600F/2.7V/0.4m#

Example: 220kJ to store, +/- 40kW, with a 90% energy efficiency

For this special application, the power availability is the main sizing criterion


Dr. P. Barrade

Example

Energy requirements : 220kJ (61Wh)

Power needs: +/- 40kW, with a 90% energy efficiency

Number of needed supercapacitors (theoretical) :

31 Scaps 2600F/2.7V

Energy available : 220kJ (61Wh) if the voltage is kept over 50% of the maximum Total stored energy : 293.8kJ (81.6Wh)

For practical reasons (energy efficiency, power availability) :

36 Scaps 2600F/2.7V are chosen" to obtain a 90% energy efficiency

" to assume the power demand

Available energy :220kJ (61Wh) if the voltage is kept over 60.36% of the maximum

Total stored energy : 341kJ (95Wh)

Final choice : 1x36 series connected Scaps (2600F/2.7V) (16.9kg, 12.9l)



18/43

18


Dr. P. Barrade


Thermal aspects

A supercapacitive tank is sized as an answer to Energy requirements

Power requirements"Available power is limited by the series resistor of the cells

"Available power is linked to the charge/discharge efficiency

Efficiency means internal losses into the cells"Internal losses act mainly as a joule effect

"Increase of temperature of the component

Temperature of a supercapacitive tank must be taken into account for a completesizing:

Natural cooling

Forced cooling

If no forced cooling possible, then increase the number of cells to maximise poweravailabilty (efficiency) and minimize losses


Dr. P. Barrade


Thermal aspects

Temperature of a supercapacitive tank must be taken into account for a completesizing

Main parameters to study thermal behavior of a supercapacitor

Density"

Easy to identify

Thermal conductivity"Generaly given by manufacturer, but deduced from experimental protocol that gives quite

vague datas

Thermal capacitance"Generaly not given by manufacturer

A way to obtain this data is to consider that supercapacitors are made of 60% ofaluminium, 25% of carbon, and 15% of water (from a thermal point of view)

Status at LEI: a complete evaluation will be made next summer


19/43

19


Dr. P. Barrade


Thermal aspects

Example: 3 cells (D-cells), mounted on a board, inside carbon fiber box.

2D finite element simulation software"Coupling of heat transfer / fluid mechanics solvers


Dr. P. Barrade


Thermal aspects

Example: Stand-by mode, 15mn warming under sunning conditions (1000w/m2)


20/43

20


Dr. P. Barrade


Thermal aspects

Example: stand-by mode, inrush air speed is 0.5m/s


Dr. P. Barrade


Thermal aspects

Example: power provided per cell is 110W, losses per cell are 11.3W (90.6%), during2400s (40mn), inrush air speed is 0.5m/s


21/43

21


Dr. P. Barrade


Thermal aspects


Horizontal gradiant temperature

For this application, forced cooling is needed, even if temperature is not stabilised


Dr. P. Barrade


Thermal aspects


Horizontal gradiant temperature

For this application, forced cooling is needed, even if temperature is not stabilised


22/43

22


Dr. P. Barrade

Limitation:

Example of a hybrid elevator

Supercapacitive tank plugged on the DC bus


Grid

AC

DC

Braking resistors

DC

AC

DC

DC

Supercapacitive

accumulator

Permanent Magnet

Synchronous Motor

C

L

me

mpmc

mw1 mw2

Shaft

Ls

u1, u2, u3

i1, i2, i3

IlUd Uc

IsUs

Ia

It

S

Ib

um1, um2, um3

im1, im2, im3


Dr. P. Barrade

Limitation:


Shaft length: 18m, 5 floors

Cabin mass: 800kg

Up to 8 passengers

Accumulator capacity: 20Wh



23/43

23


Dr. P. Barrade

Limitation:


Tests on strategies for energy management"

Rule Based vs. Dynamic Programming


0 20 40 60 800

25

50

75Scaps Energy Profile

Energy[kJ]

Rules

0 20 40 60 800

25

50

75

Energy[kJ]

Mission

DP


Dr. P. Barrade


Limitation:

Example of a hybrid vehicle: Power requirements are easy to clearly identify

Energy requirements are not so easy to identify"Need a deep knowledge on the system

"Strongly affected by strategies for storing/supplying


24/43

24


Dr. P. Barrade

Series connection of supercapacitors :

Power Electronics Converters

Power losses in the associated power converter are related to thecharging/discharging current of the supercapacitors.

The operating voltage (Scaps voltage) must be much more higher thanthe forward voltage caused by conduction in the needed converter

To increase the efficiency for a given power

Decrease the charging/discharging current in the supercapsIncreasing the total voltage of the supercaps

A series connection of supercapacitors is required


Dr. P. Barrade

Unbalanced voltages: consequences

There are differences between the Scaps values


Uc1

I

Uc2

C1

C2

U

Voltages across C1and C2will not be the same at the end of a

charging process

3 cases have to be considered : Ideal case : C1=C2

Real case : C1$C2, but the supercapsmaximum voltage may not be reached

Ideal Real case : C1$C2, but a deviceensures the voltages sharing


25/43

25


Dr. P. Barrade

Unbalanced voltages: consequences

The charging process is stopped as soon as one Scap reaches its maximumvoltage


C1=C2C2=80% of C1

No sharing

C2=80% of C1Sharing

Uf (V) 5 4.5 5

Uc1f (V) 2.5 2 2.5

Uc2f (V) 2.5 2.5 2.5

E (J) 6250 4500 5625


Dr. P. Barrade

Unbalanced voltages in the series connection of supercapacitors

Because of differences between the various capacitances

Consequences after various charge/discharge cycles

Risks of over-voltages on several cells (those of lowest capacitance)

As the charge must be stopped as soon as one cell reaches its maximumvoltage (that one of lowest capacitance)

"The cell of high capacitance are far away from the full state of charge

"The totat amount of stored energy can not be obtained

"Needs in circuits for the voltage equalization



26/43

26


Dr. P. Barrade


Voltage equalization

Voltage sharing solution, using power electronics solutions to offer a highefficiency.

C1

C2

C3

L1

L2

T1

D1

T2

D2

T'2

D'2

T'3

D'3

I

i1

i2

il1

il2

i'2

i3

C1

C2

C3

T1

T2

T3

D2

D3

D1

Np1

Np2

Np3

Df

Nf

I

i1

i2

i3Centralized flyback dc-dc

converter with distributed

secondary

association of buck-boost

dc-dc converters

forward dc-dc converterwith distributed primary


Dr. P. Barrade


Voltage Equalization

Voltage sharing solution, using dissipativeelements offer also a high efficiency.

High performances obtained thanks to anefficient control and management of voltageequalization processes

Supercapacitor manufacturers are able topropose ready-to-use solutions, directlyintegrated into a modular supercapacitivetank

Cell balancing

Module to module balancing

Integration of protection against short-circuits

Voltage monitoring for external control

"

Up to 1kV!!!!!



27/43

27


Dr. P. Barrade


Power electronics interfaces :

During charging and discharging, the voltage across a supercapacitors bank isvarying :

A power interface between the Scaps bank and its load has to be defined :

Example : interface between a Scaps bank and a DC bus

Scaps

bank

Power

Converter

DC bus

Which topology ?

Wc =

1

2CU

c

2I

c = C c

dt


Dr. P. Barrade



Two solutions : using a buck or a boost topology

Scapsbank

BuckConverter

DC bus

Scaps

bank

Boost

Converter

DC bus

Buck converter Boost converter

The current provided by the Scaps is

strongly discontinuous

A maximum number of series

connected Scaps is needed

The current provided by the Scaps iscontinuous

The number of series connected Scapscan be minimised


28/43

28


Dr. P. Barrade



Two solutions : using a buck or a boost topology

Huge number

of series connected

Scaps :

Large number ofactive components

Safety problems

High cost

High efficiency

Reduced number

of series connected

Scaps :

reduced number of

active components

Low cost

easier symetrizingprocess

Low efficiency

The boost topology offers more advantages


Dr. P. Barrade



using a boost topology : association of a Boost and a buck converter

Scaps

bank

DC bus

Scaps

bank

DC bus

When the DC voltage is nearly

constant and can not be lower

than that one of the Scaps

When the DC voltage varies

strongly and can become much

lower than that one of the Scaps


29/43

29


Dr. P. Barrade


Adapting the voltage-level with transformers Voltage adaptation with an intermediary AC-link with MF-transformer

topology with resonant mode



Dr. P. Barrade


Increasing efficiency with ZVT/ZCS Technology Topology : MF-AC-link with ZVT/ZCS converters



30/43

30


Dr. P. Barrade

Energy Storage / Energy Buffer

Are supercapacitors able to store enough energy for a powering a bus ?

0 100 200 300 400 500 600 700 800 900 1000-1

0

1

2

3

4

5

6

7

8

9x 10

7

t (s)

Energie

(J)

0 100 200 300 400 500 600 700 800 900 1 0000

10

20

30

40

50

60

70

80

90

100

t (s)

Vitesse

(km/h)

From Bellerive to St Franois5km / 120m

The needed energy is 84MJ (23.3kWh)

19900 Scaps (1800F) / 7.46m3/ 7.96T



Dr. P. Barrade


Supercapacitors are not able tostore enough energy for acomplete run

Some intermediary re-loadingstages have to be defined

Bus

Supercondensateurs

DEPART

STATION 1

STATION 2

STATION n

ARRIVEE



31/43

31


Dr. P. Barrade


7 loading stations

4160 supercapacitors1800F/2.5V

26x160 series connected

total energy : 23.4MJ(6.5kWh)

operational energy :

17MJ (4.75kWh) Time for loading : 20s

Current for loading :2.6kA

1.6m3 / 1.7T



Dr. P. Barrade


The power absorbed bythe bus is the mirror of the

power provided by thesupercapacitors

The loading of thesupercapacitors needs toabsorb high magnitudepower on the network :

1MW x 7 times x 20s



32/43

32


Dr. P. Barrade

Energy Storage / EnergyBuffer

when loading the mainsupercapacitors, theenergy is taken on fixsupercapacitors

to prepare the coming ofthe next bus, the fixsupercapacitors have tobe re-loaded :

10mn instead of 20s

the power absorbed onthe network is low

Bus Supercondensateur

DEPART

STATION 1

STATION 2

STATION n

ARRIVEE

Supercondensateursintermdiaires

s1 s2

Supercondensateursintermdiaires

s1 s2



Dr. P. Barrade


The power provided bythe network is the sum ofthe low power absorbedby each loading station

The power provided bythe network is the realmean power needed by thebus

The power provided bythe network is less than100kW



33/43

33


Dr. P. Barrade


The energy density of supercapacitors is too low for most of the applications It is often impossible to use supercapacitors are single energy storage devices to give

the complete autonomy of a system

Thanks to their power availability, supercapacitors are mainly used as energy buffers"To minimize power constraints on a main energy source

"To allow an efficient energy management

"To allow the recovery of energy when possible


Supercapacitors are mainly used:

- as energy buffers (hybrid systems)

- as main energy sources for applications with reduced energy needs


Dr. P. Barrade

Applications for supercapacitors: elevators

Variable frequency drives for elevators

Elevators are intrinsically reversible systems

3

!"

#"

$"

Conventional feeding

Non-Reversible

Efficiency increase

Reversible front-end

Efficiency increase

Local accumulator


34/43

34


Dr. P. Barrade


Solutions for allowing an efficiency increase

Recovering of energy

Reversible front-end

"Solve the problem of energy recovering

"Does not solve the problem of power fluctuations on the grid

It is reinforced

Local accumulator

"Solve the problem of energy recovering

Depends on the size of the accumulator

Depends on the control

"Can solve the problem of power fluctuations on the grid

Depends on the size of the accumulator


Dr. P. Barrade


Structure and objectives

Structure

Objectives

Increase of the global efficiency

Limitation of power fluctuations on the grid

GridAC

DC

Braking resistors

DC

AC

DC

DCSupercapacitive

accumulator

Permanent Magnet

Synchronous Motor

C

L

me

mpmc

mw1 mw2

Shaft

Ls

u1, u2, u3

i1, i2, i3

IlUd Uc

IsUs

Ia

It

S

Ib

um1, um2, um3

im1, im2, im3


35/43

35


Dr. P. Barrade


Tests on an elevator

Considered elevator

Shaft length: 18m, 5 floors

Cabin mass: 800kg

Up to 8 passengers

Accumulator capacity: 20Wh


Dr. P. Barrade


Tests on an elevator

Experimental results

0 20 40 60 800

2

4

6

Grid Power Profile

Power[kW]

Elevator

0 20 40 60 800

2

4

6

Power[kW]

Rules

0 20 40 60 800

2

4

6

Power[kW]

Mission

DP

0 20 40 60 800

100

200

300Braking Resistor Energy Profile

Energy[kJ]

Mission

Elevator

Rules

DP


36/43

36


Dr. P. Barrade


Test on strategies

Experimental results

0 20 40 60 800

25

50

75Scaps Energy Profile

Energy

[kJ]

Rules

0 20 40 60 800

25

50

75

Energy

[kJ]

Mission

DP


Dr. P. Barrade

Diesel-electric trains

Well-established technology on railways systems

Lines of low traffic potential

Reduced costs compared to the infrastructure costs of a line-powered trains

Principle:

Applications for supercapacitors: hybrid vehicle


37/43

37


Dr. P. Barrade


Main disadvantage Diesel engine has to assume all power and energy needs

"Strong speed/torque fluctuations

Efficiency, Emissions

Losses into the energy transfer chain"

Efficiency of asynchronous generator, power converters, asynchronous motors

Use of resistors during braking modes



Dr. P. Barrade


How to increase efficiency Use of an energy storage tank

"To minimize power constraints on diesel engine (decoupling of energy and power needs)

"To allow the control of the diesel engine at its maximum efficiency, or switch it off

"To enable energy recovering during braking phases

technology ofsupercapacitors

They are powercompatible

Life time / number ofcycles compatibles

It has to be checked ifthey are energycompatible!



38/43

38


Dr. P. Barrade

Case of study

GTW train (Stadler Rail AG, CH) Total weight (w/o load): 67t

Total weigth: 84t

Diesel engine power: 2x380kW

Max. power at the wheels: 620kW

Max. speed: 140km/h



Dr. P. Barrade

Case of study

Track: Merano-Malles (north of Italia)

Power profile

Altitude variation

0 2000 4000 6000 8000 10000 12000 14000 16000 18000-2000

-1500

-1000

-500

0

500

1000

Wheel power for typical itinerary

Time (s)

Power(kW)

InstantaneousMean

0 2000 4000 6000 8000 10000 12000 14000 16000 180001000

1100

1200

1300

1400

1500

1600

1700

1800

Altitude variation for a typical itinerary

Time (s)

Altitude(m)



39/43

39


Dr. P. Barrade

On-board stored energy versus diesel-engines power constraints

Main results Reduction of required diesel generator power as a function of stored energy

0 100 200 300 400 500 6000

100

200

300

400

500

600

700

Downsizing the maximal power of the diesel motor

Stocked energy in the supercapcitive tank (MJ)

Dieselmotorpowerneeded(kW)



Dr. P. Barrade

In hybrid vehicle, supercapacitors enable

To lower the sizing of thermal engines/batteries

To increase efficiency

Control of the thermal engine on its maximum efficiency map

Energy saving during braking

For catenary- fed vehicles

Increased efficiency

Limitation of power constraints on the grid

"More vehicles on a line without modifying the infrastructures



40/43

40


Dr. P. Barrade

Uninterruptible Power Supplies (UPS applications)

Compared with application with batteries, supercapacitors cannot propose anequivalent autonomy

Thanks to their power density, Supercapacitors can offer:

A reduced charging time (to reconfigure faster the UPS)

A larger lifetime

A maintenance free UPS


IN

AC

DC

DC

AC

DC

DC

OUT

Switch

Rectifier Inverter

dc/dc interface

ScapsTank


Dr. P. Barrade

Uninterruptible Power Supplies (UPS applications)

Experimental results on a 500W UPS Batteries have been replaced by supercapacitors and their power converter

5 Scaps 1800F, series connected

Autonomy: 60sec for a 300W load

0.2 0.25 0.3 0.35 0.4 0.45 0.5-400

-200

0

200

400

Uin

(V)

0.2 0.25 0.3 0.35 0.4 0.45 0.5

0

5

10

15

20

Icap

(A)

0.2 0.25 0.3 0.35 0.4 0.45 0.5-400

-200

0

200

400

t (s)

Uout

(V)

0.05 0.1 0.15 0.2 0.25-400

-200

0

200

400

t (s)

Uout

(V)

0.05 0.1 0.15 0.2 0.25-40

-30

-20

-10

0

10

20

t (s)

Icap

(A)

Network failure Reconfiguration



41/43

41


Dr. P. Barrade

Wind turbines

Wind Turbine Pitch Control Systems

Voltage Regulation and VARS Support

Short term energy storage



Dr. P. Barrade

Application for airplanes

New airbus A380

16 doors per Aircraft (Basicversion)

Electrically operated

2 main doors in permanent use forboarding

14 rescue doors for emergency use

local door controller integratedwithin each passenger door




42/43

42


Dr. P. Barrade


New airbus A380

Requirements on AC level

Operational requirements

Doors Operation independent from AC electrical system

Emergency opening even after transversal break of the fuselage

Local energy storage

High reliability

Extremely high availability

A/C System Requirements

Minimum burden to the A/C Electrical System (max. 130VA, no peak loads)

Minimum radiated and conducted distortion

Maximum radiated and conducted susceptibility

Robustness for primary power interrupts and transients




Dr. P. Barrade


Environmental and operating conditions

Normal (severe) operating temperature -40 +60oC (+70oC)

Average operating temperature +45 +55oC

Ground survival temperature -55 +85oC

Temperature gradients up to 5K per min.

Operational shock (crash) up to 20g

Operational vibrations (random sinus) with up to 4,1g

Vibration frequency 2kHz down to 10Hz

Application to water, fluids, sand and dust, fungus, fire, lightning etc.

Environmental requirements, equipment in aircraft doors:

Power supply with nominal 115VAC, variation range 96 130VAC

Wild frequency network nominal 400Hz, variation range 360 800Hz

Therefore

HW and SW designed with assurance level A

Failure rate of critical blocks 10-7 10-8 per flight hour

Only achievable with overall double resp. triple redundancy

Useful life 25 years resp. 140.000 flight hours

No scheduled maintenance is allowed for the equipment




43/43


Dr. P. Barrade


New airbus A380

Energy storage device used for the doors: supercapacitors Normal operation mode

Emergency operation mode

Consists of 56 UltraCaps PC100G (C = 100F each)

Arranged in 14 lines and 4 columns, connected by current rails

Ctotal = 28,5 F

Umatrixmax = 34 V

Ucelltyp = 2,2 V, Ucellmax = 2,5 V 13.500 Ws (typ), 16.500 Ws (max)

ESR < 50mOhm

Total weight of Capacitors 2.200g

Mechanical fixture with fixing grid




Dr. P. Barrade

Conclusion

For most of applications, supercapacitors are used to smooth power fluctuations on amain energy source

Reduced energy density

High power density

Long lifetime

Supercapacitive tank can be sized in a 2 steps process:

Energy requirements: this defines mainly the number of components

Power requirements: in order to match the required power availability

Supercapacitors technology seems to be now mature enough for large scaleapplications

Price

Performances

However: needs in strong developments in power electronics, competition withother technologies (flywheel)

Date post:	02-Jun-2018
Category:	Documents
Upload:	marko-petkovic
View:	215 times
Download:	0 times

EnStorage_Scaps

Documents