chapter 6_energy storage+ electric vehicles_feb 2011.pdf

8/10/2019 Chapter 6_Energy Storage+ Electric Vehicles_Feb 2011.pdf

1/168

Green Energy Course-

Renewable Energy Systems

Bin san: Nguyn Hu PhcKhoa in- in T- i Hc Bch Khoa TPHCM


2/168

Energy Storage Systems For

Advanced Power Applications

Paulo F. Ribeiro, Ph.D., MBA

[email protected]

Calvin CollegeGrand Rapids, Michigan, USA


3/168


4/168

Abstract

Energy storage technologies do not represent energy sources

Provide valuable added benefits to improve:

stabil ity, power quality and security of supply.

Battery Technologies

Flywheel Technologies

Advanced / Super Capaci tors

Superconducting Energy Storage Systems


5/168

Introduction

Electric Power Systems - Experiencing Dramatic Changes

Electric load growth and higher regional power transfers in a largely interconnectednetwork: >>complex and less secure power system operation.

Power generation and transmission facil ities - unable to meet these new demands

Growth of electronic loads has made the quality o f power supply a critical issue.

Power system engineers facing these challenges - operate the system in more aflexible.

In face of dis turbances - generators unable to keep the system stable.

High speed reactive power control i s possible through the use of flexible actransmission systems (FACTS) devices.

Better solution: rapidly vary real power without impacting the system through powercirculation.

Recent developments and advances in energy storage and power electronicstechnologies


6/168

Energy Storage Systems for Advanced Transmission and Distribution

Applicat ions

Energy Storage Technology Power Convert

Factors:The amount of energy that can be stored in the device.The rate at which energy can be transferred into or out of the storagedevice.

Power/Energy ranges for near to mid-term technology have projected

Integration of energy storage technologies with Flexible AC TransmissionSystems (FACTS) and custom power devices are among the possibleadvanced power applications utilizing energy storage.


7/168

10 100 10001

Energy (MWsec)

Power(MW

)

Capacitor

SMES

Flywheel Batteries

Power vs. Energy Ranges

for Near to Midterm Technology

Benefits: transmission enhancement, power oscillation damping,dynamic voltage stability, tie line control, short-term spinningreserve, load leveling, under-frequency load shedding reduction,circuit break reclosing, sub-synchronous resonance damping, andpower quality improvement.

1

10

100


8/168

Storage TechnologiesMain Advantages(Relat ive to others)

Disadvantages(Relat ive to others)

Power

Application Energy

Appl icat ion

Pum ped Storage High Capac ity, Low Cost Spec ial S ite Requiremen t

Compressed Air High Capac ity, Low Cost Spec ial S ite Requirement,Need Gas Fue l

F low Batteries:RegenesysVanad ium RedoxZinc Bromine

High Cap ac ity,Independent Power andEnergy Ratings

Low Energy Dens i ty

Metal-Air Batteries Very High EnergyDensity

Electric Charging is Difficult

Sod ium Sul fur (NAS)Battery

H igh Power & EnergyDensit ies,High Eff ic iency

Product ion Cost,Safety Concerns(addressed in des ign)

Li-ion Batteries H igh Power & EnergyDen sities, High Eff ic iency

High Product ion Cost,Requires Spec ial ChargingCircuit.

Ni-Cad Batteries High Power & EnergyDensit ies,Eff ic iency

Other Advanced Batteries High Power & EnergyDensit ies,High Eff ic iency

High Product ion Cost

Lead-Ac id Batteries Low Capital Cost L imited Cyc le Li fe whenDeeply Discharged

Flywheels High Power Low Energy dens ity

SMES, DSMES H igh Power Low Energy Dens i ty , H ighProduct ion Cost

Doub le Layer Capac itors(SuperCapac itors)

Long Cyc le Li fe, H ighEff ic iency

Low Energy Dens i ty

Source ASA


9/168

A. Superconducting Magnetic Energy Storage (SMES)

ControllerCoil Protection

Cryogenic

System

VCoil

ICoil

DewarPower Conversion System

CSI

orVSI + dc-dc chopper

Transformer Bypass

Switch Coil

AC

Line


10/168

A. Superconducting Magnetic Energy Storage (SMES)


11/168

Theimage cannotbedisplayed. Your computer may nothaveenough memory to open theimage,or theimagemay havebeen corrupted.Restartyour computer,and then open thefileagain. Ifther ed x stillappears,y ou may haveto deletetheimageand then insertitagain.

Solenoid Configuration(100 MJ 4kA - 96MW System)

A. Superconduct ing Magnetic Energy Storage (SMES)


12/168

SMES efficiency and fast response capability (MW/millisecond) havebeen, and can be further exploited in applications at all levels ofelectric power systems. Potential applications have been studied since1970s.

a) load leveling,b) frequency support (spinning reserve) during loss of generation,c) enhancing transient and dynamic stability,d) dynamic voltage support (VAR compensation),e) improving power quality,f) increasing transmission line capacity, thus enhancing overall security

and reliability of power systems.

Further development continues in power conversion systems and controlschemes, evaluation of design and cost factors, and analyses forvarious SMES system applications..

A. Superconduct ing Magnetic Energy Storage (SMES)


13/168


14/168

B. Battery Energy Storage Systems (BESS)

Batteries are one of the most cost-effective energy storage

technologies available, with energy stored electrochemically.

Key fac tors in battery for storage applicat ions include: high

energy density, high energy capabil ity, round trip efficiency,

cycling capabili ty, l i fe span, and init ial cost.

Battery technologies under consideration for large-scale

energy storage.

Lead-ac id bat ter ies can be designed for bulk energy storage

or for rapid charge/discharge.

Mobile applications are favoring sealed lead-acid battery

technologies for safety and ease of maintenance.

Valve regulated lead-acid (VRLA) batter ies have better cost

and performance characteristics for stationary applications.

Photo Source: UP Networks


15/168

BESS Example Transmission/Distribution Application

Lead-acid batteries,have been used in afew commercial andlarge-scale energymanagementapplications.The largest one is a40 MWh system inChino, California,built in 1988. Thetable below lists and

compares the lead-acid storagesystems that arelarger than 1MWh.


16/168

C. Advanced / Super / Capacitors

CVq =

d

AC

e=

2

2

1CVE =

tot

tot

RiC

dtidV *+*=

The amount of energy a capacitor is capable of storingcan be increased by either increasing the capacitance orthe voltage stored on the capacitor.

The stored voltage is limited by the voltage withstandstrength of the dielectric.

As with batteries, the turn around efficiency whencharging/discharging capacitors is also an importantconsideration, as is response time.

The effective series resistance of the capacitor has asignificant impact on both. The total voltage changewhen charging or discharging capacitors is shown in

equation


17/168

NESSCAP 10F/2.3V

C. Advanced / Super / Capacitors


18/168

Advantages Disadvantage

Power (higher density) Energy DensityEnergy Efficiency (higher)Maintenance

Discharge

Parameters Electrostatic Cap Ultra-Cap BatteryDischarge 10E-3-6 sec 1-30 sec 0.3-3 hoursCharge 10E-3-6 sec 1-30 sec 1-5 hours

Energy Density 10E4Wh/kg 10-20E4Wh/kg 5-200Wh/kgCharge Eff. ~1.0 0.9-0.95 0.7-0.85Cycle life infinite >500,000

Ness Caps

C. Advanced Capacitors


19/168

D. Flywheel Energy Storage (FES)

Flywheels can be used to store energy for power systemswhen the flywheel is coupled to an electric machine.

Stored energy depends on the moment of inertia of the rotorand the square of the rotational velocity of the flywheel..Energy is transferred to the flywheel when the machineoperates as a motor (the flywheel accelerates), charging theenergy storage device. The flywheel is discharged when theelectric machine regenerates through the drive (slowing theflywheel).

E = 21I

2I =

2

r2mh

The energy storage capability of flywheels can beimproved either by increasing the moment of inertia ofthe flywheel or by turning it at higher rotationalvelocities, or both.

Active Power, Inc.

The moment

of inertia (I)depends onthe radius,mass, andheight(length) of therotor


20/168

=

=FW

D. Flywheel Energy Storage (FES)

Flywheel energy storage coupled

to a dynamic voltage restorer.


21/168

Manufacturer Technology Capacity (kW) Capacity (time)

A Flywheel 120 kW 20 sec

B Flywheel/Battery 160 kW 15-30 min

C Battery 3.1 - 7.5 kVA 15 min

Battery 0.7 - 2.1 kVA 10 min

Battery 700 - 2100 kVA 13 min

Battery 7.5 - 25 kVA 17 min

D Battery 1250 kVA 15 min

Flywheel 700 kW 10 min

E Battery 450 - 1600 kVA 6-12 min

F Flywheel/Battery 5-1000 kVA 5-60 min

G Battery 0.14 - 1.2 kVA 5-59 min

H Battery 0.28 - 0.675 kVA 15 min

Source: EPRI

Example End-User Application

Energy Storage / UPS Systems


22/168

Advanced Power Systems Applications

SMES can inject and absorb power rapidly, but battery and flywheel systems are modularand more cost effective. Advanced flywheels and advanced capacitor technologies are stillbeing developed and are emerging as promising storage technologies as well.

Performance \ ESS SMES BESS FES Advanced

capacitor

Dynamic Stability

Needs to be

exploredTransient Stability

Voltage Support

Area Control/ Frequency

Regulation

Transmission Capability

Improvement

Power Quality Improvement


23/168

A. Integration of Energy Storage Systems into FACTS Devices

FACTS controllers are power electronics based devices that can rapidly influence thetransmission system parameters such as impedance, voltage, and phase to provide fastcontrol of transmission or distribution system behavior.

FACTS controllers that can benefit the most from energy storage are those that utilize avoltage source converter interface to the power system with a capacitor on a dc bus. Thisclass of FACTS controllers can be connected to the transmission system in parallel(STATCOM), series (SSSC) or combined (UPFC) form, and they can utilize or redirect theavailable power and energy from the ac system.

Without energy storage, FACTS devices are limited in the degree of freedom andsustained action

DeviceMVA

FACTs DeviceReactive Power (Q)

Real Power

from SMES Converter Losses


24/168

A. Integration of Energy Storage Systems into FACTS Devices

Advanced Solut ions

Transmission

Link

EnhancedPower

Transfer andStability

Line

Reconfiguration

FixedCompensation

FACTS

EnergyStorage

BetterProtection

IncreasedInertia

BreakingResistorsLoad

Shedding

FACTS

Devices

Traditional Solut ions

SVCSTATCOMTCSC, SSSCUPFC

Steady State

Issues

Voltage LimitsThermal LimitsAngular Stability Limits

Loop Flows

Dynamic

Issues

Transient StabilityDamping Power

SwingsPost-ContingencyVoltage ControlVoltage Stability

Subsynchronous Res.


25/168

Generation Transmission Distribution End-User

Energy Storage for

SpinningReserveLoad Leveling

SpinningReserveLoad Leveling

Transmission Cap.ReliabilityStability

ContinuityReliabilityPower Quality

Power Quality

Functions

Configurations

Shunt Comp. Shunt / Series Comp. Shunt / Series Comp. Shunt Comp.

Applications

StatcomPQ Parks

Arc FurnaceFACTS Devices

A. Integration of Energy Storage Systems


26/168


27/168

The performance of a power-electronics -energy-storage-enhanced device is verysensitive to the location with regard togeneration and loads, topology of thesupply system, and configuration andcombination of the compensation device.

STATCOM with SMES

STATCOM/SMES dynamicresponse to ac systemoscillations


28/168

2 STATCOMs 1 STATCOM + SMES

Voltage and Stability Control Enhanced Voltage and Stability Control

60.8

59.2

time (sec)time (sec)

(2 x 80 MVA Inverters) ( 80 MVA Inverter + 100Mjs SMES)

60.8

59.2

60.8

59.2

time (sec)

No Compensation

STATCOM with SMES

Location and Configuration Type Sensit ivity


29/168

FACTS with BESS

+_

ExternalPowerBus 2

ExternalPowerBus 1

R1 R2

S1

SS

S

23

C

C C

filter

dc1 dc2

Cfilter

Lfilter

4

1 2

Battery

PC - DSP - basedcontrol system

ReferenceValues

Six ControlSignals

Six ControlSignals

MeasuredValues


30/168


31/168

(a) STATCOM vs

STATCOM/BESS

(b) SSSC vs SSSC/BESS (c) STATCOM/BESS vs

SSSC/BESS vs UPFC

Active power f low between areas

FACTS with BESS


32/168

Voltage at Area 2 bus

(a) STATCOM vs

STATCOM/BESS

(b) SSSC vs

SSSC/BESS

(c) STATCOM/BESS

vs SSSC/BESS vsUPFC

FACTS with BESS


33/168


34/168

C. Power Quality Enhancement with Energy Storage

Custom power devices address problems found at distribution level,such as voltage sags, voltage swells, voltage transients andmomentary interruptions.

The most common approaches to mitigate these problems focus on

customer side solutions such as Uninterruptible Power Supply (UPS)systems based on battery energy storage.

Alternative UPS systems based on SMES and FESS are also available.

==

=

Dynamic voltage restorer (DVR) with capacitor storage


35/168

STATCOM

Reactive Power Only

Operates in the

vertical axis only

STATCOM + SMES

Real and Reactive Power

Operates anywhere within the

PQ Plane / Circle (4-Quadrant)

P

Q

The Combination or Realand Reactive Power willtypically reduce the Rating ofthe Power Electronics front

end interface.Real Power takes care ofpower oscillation, whereasreactive power controlsvoltage.

The Role of Energy Storage: real

power compensation can

increase operating control and

reduce capital costs

P - Active Power

Q - Reactive Power

MVA Reduction

FACTS + Energy Storage


36/168

VSI CSI

Natural Forced

Synchronous PWM

Hard Soft

Two-Level Multi-Level

SCR GTO IGBT MCT MTO

System

CommutationApproach

SwitchingTechnology

TransitionApproach

CircuitTopology

DeviceType

Power Electronics - Semiconductor Devices

Decision-Making Matrix


37/168

X

E1 / 1E2 / 2

IP&Q

Plus Energy Storage

Regulating Bus Voltage + InjectedVoltage + Energy Storage

Can Control Power FlowContinuously, and Support OperationUnder Severe Fault Conditions(enhanced performance)

Universal Topology + Energy Storage Implementation


38/168

Cost Considerations

Energy storage system costs for a transmission application are driven bythe operational requirements.

The costs of the system can be broken into three main components:

The energy storage system,

The supporting systems (refrigeration for SMES is a big item) and

The Power Conversion System.

The cost of the energy storage system is primarily determined by the amount of

energy to be stored. The configuration and the size of the power conversion systemmay become a dominant component for the high-power low-energy storageapplications. For the utility applications under consideration, estimates are in therange of $10-100K per MJ for the storage system.


39/168

Cost Considerations

In order to establish a realistic cost estimate, the following steps aresuggested:

identify the system issue(s) to be addressed;

select preliminary system characteristics:

define basic energy storage, power, voltage and current requirements;

model system performance in response to system demands to establisheffectiveness of the device;

optimize system specification and determine system cost;

determine utility financial benefits from operation;

compare systems cost and utility financial benefits to determineadequacy of utilitys return on investment,

compare different energy storage systems performance and costs


40/168

Technology & Cost Trends

I

$$$

$

I

additional cost savings possible

$


41/168

Conclusions

Potential performance benefits produced by advanced energy storageapplications:

improved system reliability

dynamic stability

enhanced power quality

transmission capacity enhancement

area protection, etc..

FACTS (Flexible AC Transmission Systems) devices which handle both

real and reactive power to achieve improved transmission systemperformance are multi-MW proven electronic devices now beingintroduced in the utility industry. In this environment, energy storage is alogical addition to the expanding family of FACTS devices.


42/168

Conclusions

As deregulation takes place, generation and transmission resourceswill be utilized at higher efficiency rates leading to tighter and moment-by-moment control of the spare capacities.

Energy storage devices can facilitate this process, allowing the utilitymaximum utilization of utility resources.

The new power electronics controller devices will enable increasedutilization of transmission and distribution systems with increasedreliability.

This increased reliance will result in increased investment in devices

that make this asset more productive.Energy storage technology fits very well within the new environment byenhancing the potential application of FACTS, Custom Power andPower Quality devices.


43/168

Storage batteries for solar and wind systems

Application of the wind turbine system

Brief state of art of storage solutions

Battery technologies: Lead Acid, NiMH and Lithium ion

Energetic models via Bond-Graph of electrochemical components

Quasi-static energetic model of fuel cell

Simple battery models: Lithium-ion and lead acid batteries

Stationary batteries for wind and solar applications: technology & simple models

Simple application examples:

A remote site

Solar pumping

Application of the studied wind turbine system: Hybridization of the DC bus with an

accumulator


44/168

2/19/2012 44

EnergyStorage+Smart Grid

Energy StorageSolutions


45/168

Energy

and

transport

2/19/2012 45


46/168

Hybrid and Electric Vehicle Designs andTheir Impact on Energy

P. T. Krein

Director, Grainger Center for Electric Machineryand Electromechanics

Department of Electrical and ComputerEngineering

University of Illinois at Urbana-Champaign, USA


47/168

Overview

Early electric cars and advantages

Energy and power issues

The modern hybrid Energy and environment motives for hybrids

and electrics

Near-term; myths and trends


48/168

Early Electric Cars Electric vehicles are clean and easy to use. Low maintenance, available infrastructure.

Electric motors were easy to control. Motors have

high power-to-

weight ratio.

1914 DetroitElectric car.

Limited range.Source: I. Pitel.


49/168

Early Hybrid Cars

The advantages of electric drives aresubstantial, but range is a challenge.

Hybrids can deliver energy for long intervals.

Retain the reliabilityand ease-of-use

advantages of

electric cars.

The 1900 Porschehybrid.

www.hybridvehicle.org


50/168

Gasoline Car Culture

The Ford Model T in 1909 made carsaffordable. Original list price: US$290.

Gasoline was a waste product of oil refining.

Low-cost mass production, low fuel costs,and performance limits helped fuel-drivencars overtake electric cars by 1920.

Reliability has been improvingcontinuously for fuel vehicles.

There was little change inelectric car technology until

the 1960s.

www.xtec.es


51/168

The relative decline of electric vehicles after 1910

2/19/2012 51

The reasons for the greater success to date of ICengine vehicles are easily understood when onecompares the specific energy of petroleum fuel to

that of batteries.

The specific energy of fuels for IC engines varies,but is around 9000 Whkg1, whereas the specific

energy of a lead acid battery is around 30Whkg1.

Once the efficiency of the IC engine, gearbox andtransmission (typically around 20%) for a petrolengine is accounted for, this means that 1800Whkg1 of useful energy (at the gearbox shaft)

can be obtained from petrol.

Specific energy means the energy stored per kilogram. Thenormal SI unit is Joule per kilogram (Jkg1).

However, this unit is too small in this context, and so theWatthour per kilogram (Whkg1) is used instead. 1Wh =

3600 J.


52/168

2/19/2012 52

To illustrate the point further, 4.5 litres (1 gallon) of petrol with a mass of around 4 kg will give atypical motor car a range of 50 km.

To store the same amount of useful electric energy requires a lead acid battery with a mass ofabout 270 kg.

To double the energy storage and hence the range of the petrol engine vehicle requires storagefor a further 4.5 litres of fuel with a mass of around 4 kg only, whereas to do the same with a leadacid battery vehicle requires an additional battery mass of about 270 kg.

With an electric motor efficiency of 90% only 27Whkg1 of useful energy (at the motor shaft)

can be obtained from a lead acid battery.

In practice this will not double the electric vehicle

range, as a considerable amount of the extraenergy is needed to accelerate and deceleratethe 270 kg of battery and to carry it up hills.

Some of this energy may be regained throughregenerative breaking, a system where the motoracts as a generator, braking the vehicle andconverting the kinetic energy of the vehicle toelectrical energy, which is returned to batterystorage, from where it can be reused.

In practice, when the efficiency of generation,control, battery storage and passing the electricityback through the motor and controller is accountedfor, less than a third of the energy is likely to be

recovered.


53/168

2/19/2012 53

Another major problem that arises withbatteries is the time it takes to recharge them.

Even when adequate electrical power isavailable there is a minimum time, normallyseveral hours, required to re-charge a lead acid

battery, whereas 45 litres of petrol can be putinto a vehicle in pproximately one minute.

The recharge time of some of the new batterieshas been reduced to one hour, but this is stillconsiderably longer than it takes to fill a tank ofpetrol.

Yet another limiting parameter with electricvehicles is that batteries are expensive, so thatany battery electric vehicle is likely not only tohave a limited range but to be more expensivethan an internal combustion engine vehicle ofsimilar size and build quality.

As a result regenerative breaking tends to be used as much as a convenient way of brakingheavy vehicles, which electric cars normally are, as for energy efficiency. For lead acidbatteries to have the effective energy capacity of 45 litres (10 gallons) of petrol, a staggering2.7 tonnes of batteries would be needed!


54/168

Revival

Revival of hybridcars about 1970.

New electronics

attempted in the1980s (GM Sunraycer).

Mature power electronics since early 1990s.

NiMH batteries maturedenough in the late 90s.

Li-ion almost there now.

eands.caltech.edu

www.treehugger.com


55/168

Revival

Maturing power electronics overcame majorperformance barriers

in the 1990s.

2000 General MotorsEV1 high-performance

electric car prototype.

Limited range. Storageproblems unresolved.

Source: www.gmev.com


56/168

Hybrid Designs Continue

The advantages of hybrids (no mechanicaldrive train) have long dominated for the

heaviest vehicles.

At the largest sizes ships and

locomotives the

diesel-electrichybrid has been

important since

the 1920s.


57/168

Energy and Power Needs

Electric motors have high power density and good control.

A car needs to store energy for range.

Alternatives: Capacitors or inductors

Flywheels or springs

Compressed air tanks

Batteries

Liquid fuel

Figures of merit: Useful storage per unit mass

Useful energy rate (power) per unit massA 90 HP electric motorbased on automotive duty.


58/168

Energy and Power NeedsStorage technologyStorage technology Energy densityEnergy density

LeadLead--acid batteriesacid batteries 100 kJ/kg (30 W100 kJ/kg (30 W--h/kg)h/kg)

LithiumLithium--ion batteriesion batteries 600 kJ/kg600 kJ/kg

Compressed air, 10Compressed air, 10 MPaMPa 80 kJ/kg (not including tank)80 kJ/kg (not including tank)

Conventional capacitorsConventional capacitors 0.2 kJ/kg0.2 kJ/kg

UltracapacitorsUltracapacitors 20 kJ/kg20 kJ/kg

FlywheelsFlywheels 100 kJ/kg100 kJ/kg

GasolineGasoline 43000 kJ/kg43000 kJ/kg


59/168


60/168

Energy and Power Needs

Rate is a problem.

Example: refill a gas tank with 60 L in 5 min.

The energy rate is roughly that of 20 majorcampus buildings!

It is costly and problematic to fill batteriesquickly.


61/168

The Modern Hybrid Efficiency and emissions improvements motivate

modern hybrid designs.

Power electronics is nearly routine.

General types: series and parallel.

Series hybrid: energy assembled electrically.


62/168

2/19/2012 62

There are two basic arrangements for hybridvehicles, the series hybrid and the parallel hybrid,

which are illustrated in Figures .

In the series hybrid the vehicle is driven by one ormore electric motors supplied either from thebattery, or from the IC engine driven generatorunit, or from both. However, in either case thedriving force comes entirely from the electricmotor or motors.

In the parallel hybrid the vehicle can either be driven bythe IC engine working directly through a transmissionsystem to the wheels, or by one or more electricmotors, or by both the electric motor and the IC engineat once.

In both series and parallel hybrids the battery can berecharged by the engine and generator while moving,and so the battery does not need to be anything like aslarge as in a pure battery vehicle.

Also, both types allow for regenerative braking, for thedrive motor to work as a generator and simultaneouslyslow down the vehicle and charge

the battery.

Series Hybrid and Parallel Hybrid Vehicles


63/168

2/19/2012 63

The series hybrid tends to be used only in specialist applications.

For example, thedi esel powered railway engine is nearly always a series hybrid,as are some ships. Some special all-terrain vehicles are series hybrid, with aseparately controlled electric motor in each wheel.

The main disadvantage of the series hybrid is that all the electrical energymust pass through both the generator and the motors. The adds considerably tothe costof such systems.

The parallel hybrid, on the other hand, has scope for very wide application. Theelectric machines can be much smaller and cheaper, as they do not have toconvert all the energy.

Series Hybrid and Parallel Hybrid Vehicles


64/168

2/19/2012 64

Alternatively, and more usefully, a parallel hybrid vehicle can use the IC engine and batteries

in combination, continually optimising the efficiency of the IC engine.

A popular arrangement is to obtain the basic power to run the vehicle, normally around 50%of peak power requirements, from the IC engine, and to take additional power from theelectric motor and battery, recharging the battery from the engine generator when the batteryis not needed.

Using modern control techniques the engine speed and torque can be controlled to minimiseexhaust emissions and maximise fuel economy. The basic principle is to keep the IC engineworking fairly hard, at moderate speeds, or else turn itoff completely.

In parallel hybrid systems it is useful to define a variable called the degree of hybridisationas follows:

The greater the degree of hybridisation, the greater the scope for using a smaller IC engine,and have it operating at near its optimum efficiency for a greater proportion of the time.

Degree of Hybridisation


65/168

2/19/2012 65

California Air Resources Board (CARB)

partial zero emission vehicles (PZEVs)

The Toyota Prius


66/168

2/19/2012 66

A nickel metal hydride battery is used. At start up or at low speeds the Prius is powered solely by the electricmotor, avoiding the use of the internal combustion engine when it is at its most polluting andleast efficient.

This car uses regenerative braking and has a high overall fuel economy of about 56.5 miles per US gallon (68miles per UK gallon).

The Prius has a top speed of 160 km/h (100 mph) and accelerates to 100 km/h (62mph) in 13.4 seconds.

The Prius battery is only charged from the engine and does not use an external socket. It is thereforerefueled with petrol only, in the conventional way.

The Toyota Prius, is the vehicle whichreally brought hybrid vehicles to publicattention. Within two years of its launchin 1998 it more than doubled thenumber of electric vehicles on the roadsof Japan.

The Prius uses a 1.5 litre petrol engineand a 33kW electric motor either incombination or separately to producethe most fuel-efficient performance.

The Toyota Prius, Parallel Hybrid


67/168

The Modern Hybrid

Parallel hybrid: energy is assembled mechanically.

Credit: Honda

Source: Mechanical

Engineering Magazine

online, April 2002.


68/168

The Modern Hybrid

The Toyota and Ford dualhybrids are parallel designs with

some series modes.

The Honda mild parallel hybrid uses a small electricmachine to recover braking

energy and allow easy engine start

and stop.

Source: Toyota


69/168

Hybrid Electric Cars -- Production

Honda Insight

Toyota Prius

Source: www.familycar.com


70/168


Honda Civic

Toyota Prius

Source: www.auto-sfondi-desktop.com

Source: www.theautochannel.com


71/168


Ford Escape

Lexus Hybrid SUV

Nissan Altima Hybrid

Source: www.edmunds.com

Source: msnbcmedia.msn.com


72/168

Motives for Electric Vehicles

Energy flexibility.

Energy efficiency.

Reduced emissions.

Cleaner, quieter carswithout performance changes.

For electric cars, the ultimate fuel source is hydro,wind, nuclear, or any electricity source.

Emissions are eliminated, or moved to a central plantwhere large-scale control is possible.

www.valvoline.com


73/168

Motives for Hybrid Vehicles

Overcome energy storage (range) and power(fuel rate) problems.

Good designs yield double the fuel economy.

In principle, it might be possible to triple thefuel economy.

The overall efficiency is similar to thermal

electric power plants.

Exhaust emission management is simplified.


74/168

Emission Improvements

Five characteristics that reduce HEV emissions:

1. The engine is smaller; electric

motor helps with peaks.

2. Shut off engine when the car stops.

3. Choose to operate engine only at

its highest efficiency.

4. Use battery energy to prepare emission controls for cold

starts.

5. Recover braking energy to batteries.


75/168

Efficiency and Emission

Improvements Efficient alternative cycles.Atkinson cycle

Brayton cycle (turbines)

The Prius achieves90% reduction inemissions; no sacrificein performance.

Large improvements in hydrocarbons andcarbon monoxide.

Possibility of zero-emission electric

operation.

Volvo turbine hybrid prototype


76/168

Electric Vehicle Emissions Aspects

Just moves emissions to a power plant.

But:

Opportunity for large emission controlinfrastructure

Resource flexibility

Higher overall system efficiency.


77/168

Emission Improvements: Electric

Emission impacts depend on generationresource mix.

Basis from average U.S. mix given here.

Large-scale reductions (>90%) inHydrocarbon emissions

Carbon monoxide

Oxides of nitrogen

Substantial reductions in carbon dioxide.

Small reductions in oxides of sulfur.


78/168

Energy Issues: Electric and Plug-In

Energy flexibility: an electric or plug-in hybridcan run on nuclear, solar, wind, or other

carbon-free resources.

Key attribute:time shifting of load.


79/168


80/168

Energy Issues: Electric and Plug-In

Electric and plug-in hybrid cars provide a newtype of large-scale flexible load.

Battery charging can be adjusted dynamicallyto help with the system match.

Possible storage resource with major benefits.

Shift load into night hours.

Nissan.com


81/168


82/168

Power Requirements

Full size car, 4000 lb loaded, axle needs:

20 HP on level road at 65 mph.

55 HP to maintain 65 mph up a 5% grade.55 HP to maintain 95 mph on level road.

Peak power of about 150 HP to provide 0-60 mphacceleration in 10 s or less.

Plus losses andaccessories.

82


83/168

Power Requirements

Easy to meet performance requirements withelectric drive train except range and refuel.

Better tradeoffs: not as much oversizing isrequired.

Hybrid design: engine delivers average needs,electric motor can manage peaks.


84/168

Energy Costs

Take gasoline at US$3.30/gallon, and a car thatachieves 30 miles/gallon.

Energy cost is $0.11/mile.

Now take electricity at $0.12/kW-h, and a carthat consumes 200 W-h/mile.

Energy cost is $0.024/mile.

Much cheaper with night charging.


85/168

Energy Costs

Expensive solar electricity (such as $0.30/kW-h), still well below hydrocarbon fuel.

Source: Evergreen Solar

PV Module Costs


86/168

Solar Power

Solar-to-vehicle is interesting:Photovoltaic module captures roughly 20% of sunlight

energy.

If a residential system is used to charge a car, this solarenergy becomes primary minimal intermediate

processing.


87/168

Charging Requirements

For plug-in charging, rates are limited byresource availability.

Residential:

10 A, 220 V outlet, about 2 kW maximum.

50 A, 240 V outlet, up to 10 kW.

Commercial:

50 A, 380 V three phase, up to 30 kW.

All are well below traction drive ratings.

87


88/168

Architectures -- Series

Probably favoredfor plug-in hybrids.

Rating 100%

Rating 30%

Rating 10%

Theimagecannot bedisplayed. Your computer may nothaveenough memory to open theimage,or theimagemay havebeen corrupted.Restartyour computer,and then open thefileagain. Ifthe red x stillappears,y ou may haveto deletetheimageand then insertitagain.


89/168

Implications

Battery charging: equipment is smallcompared to car systems integrate into

vehicle.

Even a modest charger, 2 kW, can recharge amodest plug-in hybrid in a few hours.

Minimal infrastructure implications.


90/168


91/168

Myth: Stepping stones

{Hybrid, electric, fuel cell} vehicle designs are a steppingstone toward longer term {hybrid, electric, fuel cell}

vehicles.

Fact: ALL vehicle designs are increments toward peoplesaspirations for personal transportation.

www.xtec.esSource: msnbcmedia.msn.com

h d


92/168

Myth: Industry as a group is converging

toward the best solutions

Existing designs are proven and capable, and should beemulated.

Fact: Hybrids on the road have not achieved the

performance levels and efficiencies ofknown electric car designs.

Brad Waddell. Used by permission.www.popularmechanics.com


93/168

Near-Term Trends

The plug-in hybrid is entering the market now.

A series design like the Chevrolet Volt has verysignificant promise.

Electric vehicle designs have a definite place.

Expect the Nissan Leaf as 2011 develops.


94/168

Near-Term Trends

Emissions impacts are large and will be moresubstantial as resources shift toward

renewables.

Renewables and plug-in vehicles complementeach other well.

Efficiency is very high compared to biofuels,

and compares favorably with petroleum.


95/168

2/19/2012 95

Hybrid Cars- Electric Cars-


96/168

2/19/2012 96

Hybrid Cars Electric Cars

Fuel Cell Solution with Zero Emission


97/168

Daimler Chrysler FC 86 kW Ballard- H2, 350 bars, hybrid- 60 units

manufactured, of which ~ 30 units in operation as of Sept 2005 (15 in the US)

2/19/2012 97


98/168

Hydrogen as An Energy Vector


99/168

2/19/2012 99

- Where does hydrogen come from?

- What devices are used for hydrogen storage?- What is hydrogen specific energy?

Hydrogen as An Energy Vector

Hydrogen is a promising candidate for energy storage, in terms of being stored inreservoirs as petroleum.

Specific Energy of Various Combustibles

2/19/2012


100/168

Hydrogen Sources

Hydrogen does not exist in natural form

Hydrogen can be get from:

Fossil: from oil, natural gas, coal

Electricity: nuclear, photovoltaic, wind, hydraulic, geothermal+ electrolysis

Heat: Thermochemical process

Photons: photo-electrolysis, photobiology, phtosynthesis +biomass transformation and fermentation

2/19/2012 100


101/168


102/168

H2 Applications


103/168

H2 Applications

2/19/2012 103


104/168


105/168

2nd Week: Storage batteries for solar and wind systems


106/168

Guillaume FONTES

Brief state of art of storage solutions

Some reminders about Accumulator technologies: Lead Acid, NiMH, Lithium ion

Stationary batteries for wind and solar applications

Simple application examples :

A remote site

Solar pumping

Application of the studied wind turbine system

Hybridization of the DC bus with an accumulator: energy management strategy

g yApplication to the wind turbine system

3rd Week: Photovoltaic systems and hybridization


107/168

Stephan ASTIER

Photovoltaic systems

Hybrid (Wind & Photovoltaic) systems

Hybridization of energetic systems : the principles

To be completed!

y y


108/168

Whole objective of the education seminar : modeling & 20 Sim analysis

f PV Wind h b id t m f l l t ifi ti n


109/168

of a PV-Wind hybrid system for rural electrification

NB: this application is studied by LSE Tunis (Tunisia) in Cooperation with LAPLACE Toulouse (France)

Iol

PM

SMbuck

buck Batterie

s

48 V

Ipv

diode

rectifier

inverter

DC/AC

Iond

GPV

IBat

Wind turbine

w

pv

Bus DC 48V

AC

Charge

s

grid230V/50hz

LAPLACE/GENESYS Facilities : grid connected hybrid

PV wind system with storage on 48V DC bus


110/168

PV-wind system with storage on 48V DC bus

Wind turbine emulator

PV Emulator

DC Low Voltage bus

sources interconnection

Dspace 1104

Pref. pv

Pref .ol[V ; I]

[Cde]

Pol

Ppv

Pbat

Variable DC

load

Supervisor

Pload

Lead acid

Accumulator

Grid inverter

230V

50Hz

grid

Pinv

A typical example of integrated design in a multi-disciplinary context :

reverse osmosis desalination unit powered by PV Wind hybrid system


111/168

Chimie Electricit

HydraulicsPressureflow

Thermics

5 domains, 8 inter-domain crossing

ChemicalD-enthalpymolar flux

ElectricityVoltageCurrrent

MechanicsTorque,ForceSpeed

reverse osmosis desalination unit powered by PV-Wind hybrid system

Multi-disciplinary approach : thinking by energetic analogies High level couplingsIntegrated design : Architecture Sizing - Management

PPVE Posmosis

PPVE

-Ptot

Hybrid PV-WindPower system

AdductionPump

Padduction

wellwell

Padd-Padd PurePure

waterwater

rejectedrejected

waterwater

Keywords :

StoredStored

waterwater

HP pumping

Inverse osmosis

desalination device



112/168

1 ) Basics on Bond Graphs (BGs)


113/168

Bond-Graphs origin

- Invented at MIT (Boston) by H. Paynter (61), formalised by D. Karnopp et R.Rosenberg- Arrived in Europe end of 70 (Pays Bas, Twente), France (Alstom)

Used in industry by :- Automotive (PSA, Renault, Ford, Toyota), EDF, Thomson, CEA, Airbus, GM,Hlion, CNES,

Main Characteristics and potentialities Modeling of Power/Energy transfers => universal language Unified formalism for any physical domain (based on energetic analogies) BGs describe system architecture : based on localized parameters modeling BGs Facilitate functional & structural decomposition of complex systems : wordBG Causal property inside : a prime importance for energy systems Derivation of Mathematical Structure (transfer functions, state equations)Warning on conflicts of association Structural Analysis (observability, controllability, stability), modal analysis(model reduction)



114/168

BGs approach : for any physical system energy is continuous & power is conservative

e : effort

f : flux

Positive way :

P = e.fP = v.i

A B A B

i

v

V VF

v

i

F

V

P = F.V

A B

e

q

f

p

I

C

generalised variables electrical variables

q

i

f

L

C

v

===

==t

0

d)(f).(eq.q.pE

i.vf.eP

f

Paynters tetrahedron



115/168

The Bond Graph : an homogeneous & multi domain modeling approach

Domains Effort (e) Flow (f) Moment (p) Displacement (q)

Electricity Voltage (V) Current (A) magnetic flux (Wb) Charge (C)

Mech Translation Force (N) speed (m/s) Impulsion (Ns) Displacement (m)

Mech Rotation Torque (N.m) speed (Rd/s) Impulsion (Nms) Angle (Rd)

Hydraulics Pressure (N/m2) Vol flow (m3/s) impulsion of P Volume (m3)

Magnetics M.M.F (A) flux derivative (V) xxxx Flux (Wb)

Chemical Chemical Potential Molar Flow xxxx Molar mass

Thermodynamics Temperature entropic Flow xxxx entropy

Acoustics Pressure (N/m2) Vol flow (m3/s) Impulsion Volume (m3)



116/168

Word Bond Graph : functional & Structural decomposition allows fixing interfaces - Power Bonds

- Information signals

Windturbine

W

C V

I

Generator

V

I=

=

TS.

~

=

V

I

V

I

DC Bus

0

==

V I

V I

DH z

AccumulatorT

S.

V

I=

~

V

IMotor PumpW

C inverseosmosis

P

Q

TS.

Chimie Electricit

HydraulicsPressure

flow Thermics

5 domains, 8 inter-domain crossings

ChimicsD-enthalpyMolar flux

ElectricityVoltageCurrent

MechanicsTorque,ForceSpeed

PV

cell array

1 ) Basic elements of BGs (monoport case)


117/168

e(t)

f

e(t)

f

Electrical equivalenceMonoports Basic elements

Effort

Source

Flow

SourceSf :F(t)Se :E(t)

symbol parameter name

e

fR: R1

R element: generic relation between effort % flux : R (e,f) = 0

o Linear case : e = R1.f

o Electricity : resistance : v = R.i

o Mechanics : friction, damping effect: T = F. (rotation)

o Hydraulics : restriction, load loss : P = R1 . Q.|Q|


118/168

Junctions (power conservative)1 ) Basic elements of BGs (monoport case)


119/168

Junctions (power conservative)

OJunction : Common effort

e1

f1e2

f21

e3 f3

e1

f1

e2

f20

e3 f3e1 = e2 = e3

f1 = f2 + f3

S(input flow) = S(output flow)

e1 = e2 + e3

f1 = f2 = f3S(input efforts) = S(output efforts)

Electricity: circuit nodes

Hydraulics: pressure nodes

Electricity: voltage drop, circuit mesh

Mechanics: speed nodes

Hydraulics : pressure drop

Electrical equivalenc

0 C

R

1

R

1Junction : Common flow

Junctions (power conservative)1 ) Basic elements of BGs (mono_port case)


120/168

e1

f1

e2

f2

m

TF e1 = m.e2f2 = m.f1

e1

f1

e2

f2

r

GY

e1 = r.f2e2 = r.f1

electricity : transformer, switching cell

mechanics : pulley, gearing (R1.1 = R2.2)

hydraulics : jack (P=F/S, Q=S.V)

electricity : hall effect sensor

electromechanical transformation

Transformer junction : TF

Gyrator junction : GY

E = f.

Cem = f.I

Junctions (power conservative)

1 ) Basic elements of BGs (monoport case)


121/168

Dee

f = 0

Dfe = 0

f

Multiports : representation of coupled circuits, coupled energy (thermodynamics),

Vector model (ex: 3D mechanics)

Example of a I multiport : coupled inductive circuit

u1 u3

u2

=

3

2

1

.

33231

23221

13121

3

2

1

i

i

i

LMM

MLM

MML

f

f

f

I: [L]I: [L]

I: [L]

fff 1

2

1)( = LE T

Detectors : link between energy / signal parts (links with control unit)

No power involved information link


122/168

1 ) Rules for establishing BGs : electricity domainthe academic way


123/168

0Se:E 1

C:C I:L

R:Ra

1ou 0

1ou 0

ATTENTION

the academic way

:

2. Choose a reference potential

1. Define a positive convention for currents in each element of the graph

3. Choose a number for each circuit node and represent it on the BG by a 0 junction

4. Represent voltage drops across each element by introducing a 1 junction with 3 bonds, two

being linked to the 0 junctions in the neighborhood of each considered element

5. Place elements (R,C,I) on the free bonds of the 1 junctions

6. Simplification of the BG : eliminate all 0 junctions linked with reference potentials. Then,supress all free bonds linked with those reference nodes. Finally, eliminate all 0 and 1 junctions

with only 2 bonds without power inversion :

E

Ra

C

N0

N1 N2

L

1 ) Rules for establishing BGs : electricity domainthe branch & mesh way


124/168

:

E

Ra

C

N0

N1 N2

L

2. Represent the mesh (series connection) E, Ra, ZL//C by a 1 junction (iso-current) on which one connects those 3 elements

Se:E 1

R:Ra

Z:ZL//C

1. Consider the 2 branches in // (C,L) as a macro component ZL//C.

0

C:C I:L

3. Represent by a 0 junction (iso-voltage) the 3 parallel branches (E,Ra) // C // L:

Se:E 1

R:Ra

0

C:C I:L

the branch & mesh way

Do it yourself on 20Sim!

1 ) Rules for establishing BGs : mechanical domain(adapt for mechanical rotation)


125/168

MF(t)

K

VM

4. Simplification of the BG : eliminate all 1 junctions with null speed (mechanical reference).Then simplify the BG by eliminating all junctions with only 2 bonds with the same orientation.

== 0)(0.)(:)(1 tan rentranttsorKM

M eeFFdt

dVMtFVJ

== dtVKFVVKCJ MKMM )0(;00)0(:)/1:(0

V = 0

3. Between two successive 1 junctions related to different speeds, insert a 0 junction with threebonds oriented to make appear the correct relative speed on the free bond. Place R & C elementson this free bond. If several elements have the same relative speed, insert a 1 junction on the free

bond of the 0 junction then insert these elements.

0

R:VM-0

F

SE:F(t)

2. For each connection between elements, affect an absolute speed vector and associate a 1junction. Place I elements on each 1 junction, then affect force sources (dont forget gravity forcefor vertical axis moving) and speed sources.

1 1

I:M

(V=0)

(VM)

1. Orientate the translation axis (position & speed). The orientation of power bonds follows thisorientation.

x > 0

V > 0

0C:1/K

VM-0

F

K

( p )

1 ) Rules for establishing BGs : mechanical domain(adapt for mechanical rotation)


126/168

R:F

SE:F(t) 1

I:M

C:1/K

F

K

4. Simplification of the BG : eliminate all 1 junctions with null speed (mechanical reference).Then simplify the BG by eliminating all junctions with only 2 bonds with the same orientation.

3. Between two successive 1 junctions related to different speeds, insert a 0 junction with threebonds oriented to make appear the correct relative speed on the free bond. Place R & C elementson this free bond. If several elements have the same relative speed, insert a 1 junction on the free

bond of the 0 junction then insert these elements.

2. For each connection between elements, affect an absolute speed vector and associate a 1junction. Place I elements on each 1 junction, then affect force sources (dont forget gravity forcefor vertical axis moving) and speed sources.

1. Orientate the translation axis (position & speed). The orientation of power bonds with followthis orientation.

MF(t)

K

VMV = 0

x > 0

V > 0

== 0)(0.)(:)(1 tan rentranttsorKM

M eeFFdt

dVMtFVJ

== dtVKFVVKCJ MKMM )0(;00)0(:)/1:(0

1 ) Rules for establishing BGs : electricity vs mechanical


127/168

MF(t)

K

VM

R1

L1

C1

U

1SE:F(t)

I:L1 ou M

C:C1 ou 1/K

R: R1 ou

Energetic analogies : Electricity Mechanics2..

2

1VC 22 .

1.

2

1..

2

1F

KxK

=

2..2

1IL

2..2

1VM

R,C,I on 1 junction R,C, on 0 junctionI on 1 junction

Kirchoff analogies : Electricity Mechanics

0)( = nodemecF0)( = nodeelecI

1 . Photovoltaic cell example: do it yourself


128/168

Vp

Ip

ICC ID

Rsh

Rs

= 1.

exp.TK

VII D

sD

VD

Ip

Vp

2nd or 3rd week with Steph and Guillaume

4) Rules for establishing BGs : introduction to hydraulics


129/168

Rules for BG setting (very close to electrical domain)

- Set a way of flow defined as the positive way of power;

- Seek all nodes with different pressures and place a 0 junction for each;

- Place a 1 junction between two 0 junctions to set the pressure drop and place elements withthe corresponding pressure drop;

- Choose a pressure reference (generally Patmosphere) and delete the associated 0 junctions withall linked bonds. Then, simplify the BG:

Example : system pump-jack of an EHA

Volumetric

pump

Hydraulic jack

W(t) Qp

P1v

P2v

Qp

load

Tp

D

TF

DPp

Qp

DF

Vv

S-1

TFDPvQv

DPp

Volumetric pump Hydraulic jack

Qp(m3/s) = D (m3).(Rd/s)

Tp = D.DPp.

DPv (N/m2) =DF(N)/S(m2)

Q(m3/s) = S(m2). Vv(m/s)

Displacement

Jack section

Jack rod velocity

4) Rules for establishing BGs : hydraulic domain


130/168

F2

Vv


- Set a way of flow define as positive way of power;

- Seek all nodes with different pressures and place a 0 junction;

- Place a 1 junction between two 0 junctions to set the pressure drop and place elements withthe corresponding pressure difference;

- Choose a reference pressure (generally Patmosphere) and delete the associated 0 junctions withall linked bonds. Then, simplify the BG:


Volumetric

pump

Hydraulic jack

W(t) Qp

P1v

P2v

Qp

load

1D

TFSf:W(t)Tp

WDP

Qp

load

R:Rch

DFVv

P1p

Qp

P2pQp

0

0

(P1p)

(P2p)

1

R:Rch

1

P1v

Qv0

(P1v)

S-1

TF

1

F1Vv

0

(P2v) STF

C:V/b

C:V/b

Fluid compressibility injack chamber

Load losses

4) Rules for establishing BGs : hydraulic domain


131/168


- Set a way of flow define as positive way of power;

- Seek all nodes with different pressures and place a 0 junction;

- Place a 1 junction between two 0 junctions to set the pressure drop and place elements withthe corresponding pressure difference;

- Choose a reference pressure (generally Patmosphere) and delete the associated 0 junctions withall linked bonds. Then, simplify the BG:


Volumetric

pump

Hydraulic jack

W(t) Qp

P1v

P2v

Qp

load

1D

TFSf:W(t)Tp

WDP

Qp

P1p

Qp

P2pQp

F2

Vv

load

R:Rch

DFVv

1

R:Rch

1

P1v

Qv0

(P1v)

S-1

TF

1

F1Vv

0

(P2v) STF

C:V/b

C:V/b Simplified 2 lines BG

1 st Week: Bond Graphs based wind turbine energy system design


132/168

Xavier ROBOAM, Guillaume FONTES

1) Some reminders about Bond-Graphs Basics (X. Roboam)

2) Some examples on Bond graph modeling and 20 Sim simulations (X. Roboam & G. Fontes)

a. Simulation of a current controlled DC DC buck chopper;

b. Simulation of a DC machine : motor generator mode

3) Some reminders about Wind Turbine systems connected to a DC electrical machine;

a. About aerodynamics and energy efficiency of wind turbines

b. Simulating wind turbine torque/speed curves with inertia and defining a load torque

characteristic: to analyze generator / load compatibility;

c. Short reminders about causality issues

d. MPPT control of a wind turbine system connected to a current controlled DC generator

4) System study of a wind turbine system connected to a low voltage 48V DC bus (X. Roboam)

a. System description and analysis

b. DC equivalent modeling of a PM synchronous generator diode rectifier device coupled on low

voltage (48V) DC bus

5) If time remaining in the first week, study of a grid connected wind turbine system coupled through a

hybrid 48V DC bus.

2. Model of a switching cell : functional model


133/168

* Instantaneous functional model as an electrical transformer (no loss)

If h : state of the cell (high = 1; low = 0)

Vs = h.VeIe = h .Is

Ve

Ie

IsTH

TB VsVs

Is

Ve

Ie

h-1

MTFSe:Ve Sf:Is

= a.

= a-1.

Vs

Is

Ve

Ie

a-1

MTFSe:Ve Sf:Is

Ton Tc

Vs

t

=Ton/Tc.

Ve

* Average functional model as an electrical transformer (no loss)

duty cycle

2. Model of a switching cell : functional model


134/168

* Logic of controlIe

VeIs

cb Vs

ch

DB

DH

Is > 0 => Sign(Is) = 1 ; Is < 0 =>

Sign(Is) = 0 Ti On => ci = 1 ; Ti Off => ci = 0

* Logic synthesis :

bh cIsc .)Sgn(+=h

Time Delay (dead times) taken into account Discontinuous Conduction (Is = 0) cannot be simulated Losses (switching & conduction) possible to estimate

ifh : state of the cell (high = 1; low = 0)

Vs = h.Ve

Ie = h .Is

Ve

Ie

IsTH

TBVs

c h cb Sign(Is) Conduction Vs

1 0 1 Th Ve0 1 1 Db 00 0 1 Db 01 0 0 Dh Ve

0 1 0 T B 0

0 0 0 Dh Ve

2. Model of a switching cell : example of a boost converter


135/168

Ve

TH

TB

LIchC

IL

Is

VC

Ve

Model with instantaneousvaluesVe = (1-CB).VC

Is = (1- CB).ILI:L

Se:Ve 1 MTF

1-CB0

C:C

Sf:IchVCVe

IL Is

CB

Average model : replace CB bya :

Ve = (1-aB).VCIs = (1-aB).IL

CB=0

Ve

THL Ich

CIL

Is=IL

VC

Ve

Simplified example : TH permanently off, TB driven b

Ich

Ve=0Ve

L

CB=1

C

IL

Is = 0

VC

2. a) Model & Simulate a current controlled buck chopper


136/168

Ve

Ie

ILTH

TBVs

L R Do it yourself on 20Sim!2a-1: with constant a=0.52a-2 : with current control

2. b) Rules for establishing BGs : electromechanical domainElectromechanical conversion


137/168

U

ImSe

u1 u2 u3 F m

0 1 0 1 0 GY 1

R: Rm

Rm Lm

U

m

I: JmI: Lm

U = Rm.Im + Lm.dIm/dt +F

m

Tm = F.Im = Fm.m +Jm.dm/dt ;

mmE W= .

mmIT .=

Em

Im

Cm

WmTload

0

1(=0)

R: Fm

U

Im

Se

R: Rm

I: Lm

1

I: Jm

Em

Im

Tm

m

GY 1

R: Fm

Tload

Tload

Jm,Fm,F

Tem

m

2. b) Model of a chopper fed DC machine


138/168

Vm

DC Machine model

1 1Se:Vm Se:Tload

I:LmDCM

load

R:Rm

f

GY

R:Fm

I:Jm

DC Machine Model fed by a bridge structure of chopper Functional model

Se:Ve 0

hG-1

MTF

hDMTF

1 MCC

VeIe1

Ve

Ie2

Ve

Ie

VGBIm

VDBIm

VmIm

MCCVe G D

H

B

T1

T2 T4

T3

IeIe1 Ie2

Vm

Im


139/168

2. b Model & Simulate a DC machine


140/168

Ve

Ie

DCM

load

torque

Do it yourself on 20Sim!Motor & generator mode



141/168







a. About aerodynamics and energy efficiency of wind turbinesb. Simulating wind turbine torque/speed curves with inertia and defining a load torque






b. DC equivalent modeling of a PM synchronous generator diode rectifier device coupled on low

voltage (48V) DC bus

5) If time remaining in the first week, study of a grid connected wind turbine system coupled through a

hybrid 48V DC bus.

3) Towards a wind turbine energetic behavior


142/168

vV W

PMSM

ai

abu

dcU

dcoI

C

dcI

batR

batE

L batI

emT =

=

=

3) Reminders on wind turbines energetic behavior


143/168

- Controlled generator (C.G) connected to the grid/load through a power electronic

deviceGSC.G

Taero(N.m)

W(rpm)

Torque(N.m)

MPPT: Maximum Power Point Tracking

3...

2

1. VSCP Paero =

3) Aerodynamics of wind turbines


144/168

Power coefficient CP versus tip speed ratio

Tip speed ratio:

max

p

p

aC

C =h

Aerodynamic efficiency :

ventV

R W=

.

pCC = )(

Torque coefficient:

Betz Limit

~ 0.47

3 pales

lopt ~ 6-7

CP

fastslow

3

...2

1

. VSCP

Paero =


145/168

3.b) Modelling & 20simulation of a wind turbine


146/168

Torque loadMSe:Twt()

I:JWT

1

Wind turbine

Vwwt

Twt

Do it yourself on 20Sim!

0 5 10 15 20temps {s}

-30

-20

-10

0

10

20

30

40

50

60

v_vent

TloadWrotTwt

)(....2

1)(

2

= CVRSVT vVw

Vw

wt

.optKloadT

=

3

3

2

1

opt

RSopt

PC

optK

=

3.c) BG model of a wind turbine driving a equivalent DC generator


147/168

N

TFMSe:Twt()

I:JWT

1

Wind turbine

Vv 1

I:Lm

R:Rm

f

GY1

R:F

m

I:J

mGCC

Causality conflict

Turbine Speed

wt

Twt

The causality conflict due to the coupling of both inertia I elements can besolved by gathering the 2 I elements (generator inertia neglected or merged withthe turbine inertia);

0

C:Cbus

)(....2

1

)(

2

= CVRSVT vVw

Buck

DC-DC converter

MTF

a,CH VoutVbus

ILIbus

I:L

1

load

Current control

storage

batt

0

Multiplier

Generator Speed

G

TG

3. c) Reminders about Causality in Bond- Graphs


148/168

f

A Be

fBA

e

f

Causality stroke : close tothe element for which theeffort is a given data

A Be

BA

e

f

Convention : causal strokeA imposes an effort (e) to B, whose effect sets the flow f towards A

Do not confuse causality wayWith power transfer orientation !

AccumulatorV isimposed

Effort,V

Flux, I

B imposes an effort (e) to A, whose effect sets the flow f towards B

3. c) Causality in Bond- Graphs


149/168

SCAP procedure (Sequential Causality Assignment Procedure)

Mandatory causality for sources

fSf :I(I>0 ou I0 ou U


150/168

Causality for junctions

0 Junction (common effort)which effort imposes its value to the others ?

=> Only 1 causal stroke close to the 0 junction

TF Junction: only 1 causal stroke close to the TF junction

mTF

1 2 mTF

1 2 mf

f

mee

2:1

1:2

=

=

1.:22.:1

fmfeme

==

01

2

3

Causal writing

e2 := e1e3 := e1f1 := f2+f3

1 Junction (common flux) f1 := f2

f3 := f2e2 := e1-e3

1

1

3

2

GY Junction

2.1 fre

1.2 fre :=

:=

rGY

1 2r

GY 21

f1 := e2/rf2 := e1/r

which flux imposes its value to the others ?

=> Only 1 causal stroke far from the 1 junction

: 0 ou 2 causal stroke close to the junction

3. c) Causality in Bond- Graphs


151/168

Sequential Causality Application Procedure (SCAP)

1: Affect mandatory causality for sources and for non linear elements R

2: Affect integral causality for C & I elements

3: propagate the causality for junctions

4. propagate causality for R elements

E

Ra

C

N0

N1 N2

L

Example for Sequential Causality Application (SCAP)

3. c) Causality in Bond- Graphs : a prime importance for energetics


152/168

Characteristics of causality in energetic systems (one of major interest of BGs!) Cause effect relationships shown off ;

Analysis of interactions (causal path and loops);

Display warnings when non physical (energetically) associations

Possibilities of systemic analysis : mode (simplification of models) &

structural analysis (controllability, observability,);

structure of mathematical equations :

integral (physical) causality : Ordinary Differential state Equations ;

existence of derivative causality: Algebro Differential state Equation ;

systematic equation derivation (state equations, transfer function/

matrix)

3.d) BG model of a wind turbine driving a equivalent DC generator


153/168

MSe:Twt()

I:JTo t

1

Wind turbine

Vv 1

I:Lm

R:Rm

f

GY1

R:F

m

I:J

mGCC

Turbine/Generator Speed

wt

Twt

the 2 I elements have been gathered : no more causality conflict Considering a direct driven generator (without multiplier) : OK for low powers

0

C:Cbus

)(....2

1

)(

2

= CVRSVT vVw

Buck

DC-DC converter

MTF

a,CH VoutVbus

ILIbus

I:L

1

Current control

load

storage

batt

0

Towards MPPT for better efficiency !!!

3.d) MPPT from power control


154/168

Method based on the Cp()characterisitc knowledge: power

control

power reference:

CP()=CPopt(opt) => Popt = Kopt.opt

3

Power rotation speed characteristic

withwith

Maximal power obtained if:

kPref kW

Ws

rad

WP

optopt fP W=

1W

1P

2W

2P

3W

3P

opt4 W=W

opt4 PP =

1

2 3 4

(opt)

Cp(opt

)

3

3RSopt

P

C

2

1optK

=Pref= Kopt.3

Kopt.3


155/168

3.d) MPPT from torque (current) control

3opt


156/168

Torque (current) reference:

CP()=CPopt(opt) => Popt = Kopt.opt

3

2.optK

optPrefemT

==

2W= optKrefemT

opt

wtwt

3ref

em TTT =

opt3

3

Convergence of algorithm

2

2W

2wtT

2refemT

1wtT

1W

1

1refemT

Ws

rad

mNT optopt fT W=

(opt)

Cp(opt)

withwith

Maximal power obtained if:

Method based on the Cp()

characteristic knowledge: torquecontrol

3

3

2

1

opt

RSopt

PC

optK

=

Torque rotation speed characteristic

3.d) BG model of a wind turbine driving a equivalent DC generator


157/168

MSe:Twt()

I:JWT

1

Wind turbine

Vv 1

I:Lm

R:Rm

f

GY1

R:F

m

I:J

m DCG

wt

Twt

(a) BuckDC-DC converter

MTF

a,CH0

C:Cbus

VoutVbus

ILIbus

I:L

1

)(....2

1)(

2

= CVRSVT vVwCurrent control

& MPPT

3

3

2

1

opt

RSopt

PC

optK

=

batV

optPrefL

I =

= .optKoptP Do it yourself& good luck on 20Sim!!!

load

storage

batt

0

X i ROBOAM G ill FONTES



158/168







a. About aerodynamics and energy efficiency of wind turbines

b. Simulating wind turbine torque/speed curves with inertia and defining a load torque






b. DC equivalent modeling of a PM synchronous generator diode rectifier device

coupled on low voltage (48V) DC bus

4.a) Medium voltage (600V) DC bus coupling of wind & PV hybrid systems

Two structures are convenient


159/168


Two structures are convenient

vV

MS

V600

busE

batI

PWM rectifierPWM rectifier

MS

dcI

dcU

Diode rectifier

C

E (t)

T (t)

batI

E (t)

T (t)

Boostchopper

Hacheur

survolteurBoostchopper

vV

1 st structure 2 nd structure)

VeryVery efficient but not cheap!efficient but not cheap!

PVPV--GenGen

PVPV--GenGen

efficient,efficient, reliablereliable and cheapand cheap

consideredconsidered asas betterbetter forfor lowlow power WT (power WT (MireckiMirecki

Wind Turbine Savonius

V600

busE

4.a) Low voltage (48V) DC bus coupling of wind & PV hybrid systems

Two structures are convenient: 48V is the stadard for stand alone systems


160/168


Two structures are convenient: 48V is the stadard for stand alone systems

V48

busE

1 st structure

VeryVery efficient but not cheap!efficient but not cheap! efficient,efficient, reliablereliable and cheapand cheap

consideredconsidered asas betterbetter forfor lowlow power WT (power WT (MireckiMirecki

vV

MS

batI

PWM rectifierPWM rectifier

E (t)

T (t)

BuckchopperPVPV--GenGen

2 nd structure)

MS

dcI

dcU

Diode rectifier

C

batI

E (t)

T (t)

Buckchopper

Buck

chopper

vV

PVPV--GenGen

Wind Turbine

V48

busE

Wind Turbine

FirstFirst weekweek

4.a) DC equivalent modeling of a PM synchronous generator diode rectifier device coupled on low voltage (48V) DC bus

di d


161/168


Iol

PM

SMbuck

48 V

Battery

diode

rectifier

DC loads

Iond

IBat

Wind turbine

w

DC Bus 48V

0 5 10 15 20

temps {s}

Pol_m

ax{W}

Pol_M

PPT{W}

0

200

400

600

800

1000

PWTopt

JbatmpptE,wtoptE

%4,11%E =

Current control

& MPPT

EWT-opt

Pbatmppt

4.b) DC equivalent model of PM synch generator connected to adiode rectifier

di d


162/168

Iol

PM

SMbuck

Batterie

s

48 V

diode

rectifier

DC loads

Iond

DC equivalent

modelling

IBat

Wind turbine

w

DC Bus 48V

Tem M, M

PMSG (Generator)E

sR

s Ls Is

V

Diode

Rectifier IDC

UDC

Tem M, M

DCG (Generator)

EDC

RDC

LDC

IDC

UDC


Diode


163/168

Tem M, M

PMSG (Generator)Es Rs Ls Is

Vs

Diode

Rectifier IDC

UDC

Tem M, M

DCG (Generator)

EDC

RDC

LDC

IDC

UDC

Rs Is

Ls cycl

j Ls cycl

Is

Es

Vs

RsI

s

Is Vs

Es

RsIs

jLs cyclIs

Es

Es

Vector diagram of synchronous generatorWith diode rectifier : cos j = 1


V E j L I R I


164/168

s s ss scycl sV E j.L . .I R .I= 2 2s s scycl s s sV E (L . .I ) R .I=

' 2 2

s s scycl sE E (L . .I )=

DC sf

3 6U V=

DC sf I I

6

=

2

2

DC s scycl DC s DC

6 6U E L I R I

3 6

=

s DC s

2

DC scycl

2

DC s

3 6E E

6L 3 L

6R 3 R

=

=

=

emM p ex s

s p ex M

C 3 n I cos

E n

=

= W

em em M M s sP C 3 E I cos= W = sDC s p ex M p DC M

emM emM

sDC s

p ex p DC

3 6 3 6E E n n

C CI I

3 n cos n cos6 6

= = W = W

= = =

DC ex

3 6 =

cos j= 1



165/168

Electromechanical conversion

emM p DC sDC

sDC p DC M

C n I cos

E n

=

= WGYEsDC

IsDC

CemM

WMsDC sDCI ' I cos=

Magnetic reaction

22

sDC sDC DC DCE ' E L I= sDC sDCE ' E cos= or

sDCsDC

I 'I

cos= TF

EsDC

IsDC

EsDC

chapter 6_energy storage+ electric vehicles_feb 2011.pdf

Documents