lyons (wind energy systems)

8/12/2019 Lyons (Wind energy systems)

1/41

Energy

Systems

Cornell

12 June, 2009

JP Lyons - CTO

Novus Energy Partners


2/41

Wind Now Mainstream

GE1.5MWTurbines

Lamar,Colorado

,

GE $6.5B 2008 revenues, 10,000 1.5 machines installed

Good US sites (8+ m/s) - lowest COE of any new generation

US 20+ GWs, 8.3 GW 2008, 42% new electricity

20% Wind Energy by 2030 300+GW

GW scale projects in sight

2 /June 2009


3/41

Land Based Technology

Vestas V100-2.75

1.5 3.0 MW Upwind Configuration

80 100 Meter Tower Height

Distributed component drivetrain Full Span Pitch Control

Ta ered C linder Steel Towers

Clipper 2.5-93

~65 kWhr/kg tower top mass

200 MW + Windfarms

Performance

98% Availability

40+% Capacity Factor at IEC-II 8.5 m/sGE 2.5xl

3 /June 2009

CF% +10 pts in last 5 yrs


4/41

GE Wind TurbinesElectrical Pitch

Drives

GE 1.5 MW 77 M Rotor Diameter

50-100 M Tower

Doubly-FedGenerator

98% Availability

Speed 10-20 RPM

Variable Pitch

Gearbox

Epoxy-GlassComposite Blades

Bearing

Transformer &Electrical Power Electronic

Converter

4 /June 2009


5/41

Turbine Speed vs. Size

Southwest Windpower Storm

Clipper 2.5 MW with 93 m

. , .

5 /June 2009


6/41

Wind Energy Conversion

Rotor power: P = 1/2 cp Avw3

cp - rotor power coefficient - a r ens y

A - rotor swept area

Ideal cp = 0.593 (Betz factor)

w ere 2 = 1 w n ve oc y s ows y

Tip speed ratio: = vt / vw

6 /June 2009

cp = f()

Windturbines: Fundamentals, Technologies, Application and Economics , Erich Hau, ISBN: 3540570640; (April 30, 2000)


7/41

Wind

TurbineDynamics

er o c orces xc te ec an ca ystem

bladepassingfrequency(BP)

3P

wind

shear,

yaw

error,

tower

shadow

Protationalfrequency

TurbineNaturalFrequencies

ower

en ng

mo es

Bladeflapbendingmode

Bladeflutter&torsional modes

7 /June 2009

Windturbines:Fundamentals,Technologies,ApplicationandEconomics,ErichHau,ISBN:3540570640;(April30,2000)

Drivetraintorsional oscillation


8/41

IEC Design Envelope

IEC 61400 defines a standard design envelope fordifferent desi n classes.

Assumes most extreme conditions for which a 20 yeardesign life can be maintained.

Air density 1.225 kg/m3, shear coefficient of 0.2 AND

IECIIIB IECIIIA IECIIB IECIIA IECIB IECIA

Mean WS 7.5 7.5 8.5 8.5 10 10

TI@15m/s 16% 18% 16% 18% 16% 18%

V50 - 3s 52.5 52.5 59.5 59.5 70 70

8 /June 2009


9/41

Loads Analysis Aero Elastic Model

9 /June 2009


10/41

Time Series BladeRootB

Main Shaft

R

T

Tower Top

LoadTime Series

Wind speedParameter Iu,,z0

10 /June 2009


11/41

Wind Turbine Performance

-

1,200

1,400

1,600

(kW)

Cut-outRated Power

400

600

800

1,000

lectricalPower

Cut-in

Wind speedWind speed

0

200

0 5 10 15 20 25

Wind Speed (m/s)

Energy in the Wind3

Captured Energy(1/2 V3 S cp)

Wind Distribution

11 /June 2009

Annual EnergyProduction (AEP)

Power Curve

Energy


12/41


13/41

Analysing the wind

a s ca me o s

(1)

Once the roughness length and the according

height exponent a is estimated, the formula (1)gives the wind speed (v2) in a projected height (h2):

=

1

212

h

hvv

(2)

Because the estimation of a is subjective, thefollowing formular gives an objective way of

calculating the height exponent out of two differenthei hts of measurement:

( )

( )21

21

ln

ln

hh

vv=

Further formulas for calculation of windcharacteristics:

Vref= 5 x Vm

Ve1 = 0.75 x Ve50

(3)

(4)Empiric ormulas according IE standards

Ve50 = 1.4 x Vref (5)

13 /June 2009


14/41

Tech Improvements

Scale 5MWmachinesontheGreatPlains

GWscalelandprojects

Logistics:insitublade&towermfg

PowerTrain

Compact1stageintegratedgearbox,

90kWhr/kgspecificyield

bearings,generator

Directdrive

PMgenerators WTCompositesSheathedSpaceFrameTower

BendTwistCoupledBlades

Controls

FullMVpowerconversion Multivariablemodelbasedcontrols

Loadmitigation&damping

Cyclic&independentbladepitchcontrol

Blades Largerrotors,higheffairfoils+10%CF

Loadmitigatingsweepandflaptwistcoupledblades

14 /June 2009

u oma e car on ersparcap a eroo

Onsitebladeinfusion

Drivetrain BearingNacelle


15/41

2-Blades: Back to the Future? Nordic1000

rotate 25-30% faster: power with less torque more blade noise

,

Eliminates weight/cost of 3rd blade - decrease in Cpcompensated by slightly longer blades

Teetered hub minimizes bending loads on the mainshaft /gears

Simplified installation logistics

Potential 25% wei ht/cost advanta e: Technolo for COE driven markets e. .

Optimized3blade Optimized2blade

Great Plains, Northern China, Offshore?

15 /June 2009


16/41

New Innovation

FloDesign Turbine

16 /June 2009

Venturi + Mixer/Ejector(Mass)

Coriol is Wind VAWT(Israel)


17/41

Wind Turbine Electrical Conversion

Type 1: Squirrel-cage induction generator - generator

PlantFeeders

Limited LVRT and pf capability

PF contro lcapacitors

generator

PlantFeeders

ype : oun ro or n uc on genera or w var a e ro orresistance

Fixed speed variable pitch turbine Slip poweras heat loss

PF controlcapacitors

ac

to

dc

Plant

Type 3: Doubly-fed wound rotor induction generator -Limited variable speed variable pitch turbine

generator

ee ers

acto

dc

acto

dc

Type 4: Full power converter interface Full variable speed variable pitch turbine

partial power

generator

PlantFeeders

acto

acto

17 /June 2009

full power

dc dc


18/41

-

Grid CodesPower & Frequency Operating Range

, ,FERC/WECC, HQ, UK, ESB, ...

Initiated by e-on 2001

LVRT/ZVRT fault ride-thru & transient volt support

Reactive power specs

Power vs, Frequency

Germany

1.1 pu

1.15 pu

For Br itain React ivePower re uired

Alberta Alberta

Austr

alia,Albert

a

AlbertaAlberta

VARSupport

VoltageTransientRideThruRequirements

Alberta,

Phillipines

, LIPA,

NSP,

PSCO,

Italy

Britain,

Scotland,Thailand,Turkey,

ERCOT,PG&E

and therest onLHS

Vo

ltage

(kV)

1 pu

1.05 pu

Rated Power, Continuous

,

is the same as that for the reduced

output power (poorer pf)

Ontario,

LIPA, NSP,

PG&E and the

rest on RHS

Iris

h,Gr

ee

ce

an

d

theres

t

on

LH

S

Britain, Irish,

Scotland,

Alberta,

Greece,

Phillipines,

Thailand,

Turkey

Austr

alia,

ERC

OT,

PSC

O,

Italy

and

rest

on

RHS

Common,

Except

Australia,

Ontario

(upto upf) Insert another image

Irish,Greece and the rest on

LHS

Irish, Greece

0.95 pu

0.875 pu

0.9 pu

Irish, Alberta, GreeceAustr

alia

and

RHS

Alberta

For ERCOT, at lower powers, Reactive

according to capability (poorer pf)

For Germany, any power level, duration

not specified. (assumed continuous)

18 /June 2009

Power Factor

0.8

50

.9

0.9

5 1

0.9

50

.9

0.8

5

Over ExcitedUnder Excited


19/41

Mimic thermal lants fre droo var su ort

Grid (Friendly) Integration

59.50

60.00

3 GW wind w/ newactive power

controls

59.50

60.00

3 GW wind w/ newactive power

controls

Powerelectronicshavechangedwindtechnology

fromadetrimenttoanattribute

ZVRTfaultridethrutoberequiredbyFERC 58.50

59.00 HQ Base case w/owind - UF LoadShed at 58.5 Hz

58.50

59.00 HQ Base case w/owind - UF LoadShed at 58.5 Hz

Reactivepowercontrol voltageregulation,VAR

supportw/o

power

Activepowercontrolramprates,powercurtailment,HydroQuebec VirtualInertia

58.00

58.0 a fbul 90 Load 220.0 1 1 60.0

58.0 b fbul 90 Load 220.0 1 1 60.0

58.0 c fbul 90 Load 220.0 1 1 60.0

58.0 d fbul 90 Load 220.0 1 1 60.0

Time( sec )

0.0 30.0

new controls

58.00

58.0 a fbul 90 Load 220.0 1 1 60.0

58.0 b fbul 90 Load 220.0 1 1 60.0

58.0 c fbul 90 Load 220.0 1 1 60.0

58.0 d fbul 90 Load 220.0 1 1 60.0

Time( sec )

0.0 30.0

new controls

,

10%Power

Increase

VoltageatPOIWindPlantVoltage

Frequency(Hz)

Power(kW)

4%FrequencyReduction

WindPlantPowerOutput

19 /June 2009

ColoradoGreen220kVBusVoltageRegulation

ActivePowerRampRateControl GE/ESBIreland


20/41

2001 NYISO Day Ahead Forecast E rror (F-A) January

Wind in New York

1500

2500

3500

Erro

Load Error (F-A)

Wind Error (A-F)

Total Error (F - A)

-1500

-500

500

1 49 97 145 193 241 289 337 385 433 481 529 577 625 673 721

Hour

M

NY RPS

25% renewables by 2013 (15% existing hydro)

Summer Morning Load Rise - Hourly Variabilit y

+ w n . ac eva e w m nor c anges n operat ons

Day-ahead uncertainty w/ wind similar to load forecast

Wind improves post-fault response of interconnected grid

100

150

200

uency

State Jun-Sep 7AM-9AM 1HR Delta Histogram

Largest Hourly Change

With Day-Ahead

Wind ForecastingWithout WindForecasting

Total variable cost reduction

(includes fuel cost, variable O&M, start-upcosts, and emission payments)

$ 430M $ 335M

Total variable cost reduction per MW-hourof wind generation

$48 / MWh $38 / MWh

$95M

0

50

-3000 -2000 -1000 0 1000 2000 3000

Freq

2756 MW with wind

NYS Benefits

$48/MWhr of Wind Energy Production Cost

Wind revenue $ 315M $ 305MNon-wind generator revenue reductions $ 795M $ 960M

Load payment reductions

(calculated as product of hourly load andthe corresponding locational spot price)

$ 515M $ 720M

MWLoad Load-Wind

20 /June 2009

CostsAnnual Operating Cost Impactsfor 2001 Wind and Load Profi les


21/41

Wind ForecastingEltra, Denmark - 2000 Study

1.9GW onshore farms, 16% consumption

3.4TWh produced, 1.3TWh miscalculated (38%)

Climatology-based forecast, inaccuracies up to 800MW

m a ance paymen s . c

Advanced forecast using a

Current State-of-the-Art

statistical models, and 3D

meso-scale climatology

Local statistical model + 3D climatology model - 10-15% mean abserror for day-ahead and 5-10% error for 6 hr ahead forecasts

2005 regulations in Spain provide:

- Penalties for >20% error on 24hr production forecast

-

2003 Cal ISO regulations unbiased hourly, daily forecasts settlementmonthly for net deviations at average rate

Utilities need short (72h) forecasts

21 /June 2009


22/41

Site Specific Power Forecasting System

Wind SpeedForecast

PowerCurve

PowerForecast

Availability Model

YieldForecast

Assume w e areDown for 5 min(t o)

K

W

K

W

For all Downtimes (t) > (to)Calculate t- to

CalculateAverag e(log( t- to ))

Stddev (log(t- to ))

Increment (to)By 1 hour

while (to)


23/41

Offshore Wind

23 /June 2009


24/41

Offshore Wind

176 MW Siemens/Bonus

90MW VestasBarrow, UK

Offshore Technology

19 Projects, 900 MW Installed, shallow water

,

3 4 MW upwind configuration

5-6 MW turbines in prototype

80 m towers

Monopile & gravity foundations < 15m

Many challenges turbine only 1/3 project costs

Performance Average 45+% Capacity Factor 11 c/kwhr UK Thames Estuary site

40 MW Bonus Middlegrunden

Farm in Copenhagen Harbor

24 /June 2009


25/41

Middlegrunden Copenhagen Harbor

25 /June 2009


26/41

Gamechanger: US Offshore Wind

Wind Map off Long Island Virginia to Boston,densest US population

LIPA lannin 140 MW ilot offshore-electric prices

Huge renewable assetwithin 50 km of coast

and less than 50 m

farm

RPS in NY, Mass, Conn RPS will drive need for large scalerenewables

Deeper water foundation technology & higher power moreeconomic turbines needed

Great Lakes close to large load centers in US & Canada Toronto, Cleveland, Detroit, Chicago, Milwaukee,

Lake Erie shallowest at 15-30 m

26 /June 2009

Foundation technology 50-70 m would enable largedeployment need to withstand ice conditions


27/41

Offshore Machines

Nacelle

Manufacturer ModelPower

(MW)

Rotor

(m)

Weight

+ Rotor

(kg)

GeneratorCf

(%)# Units

Enercon E112 4.5 112 440 WF Sync 44.0 5

Enercon E120 6 120 440 WF Sync 41.6 0*

.

Vestas NM110 4.2 110 214 DFIG 44.6 1

Vestas V120 4.5 120 214 DFIG 46.5 0*GE 3.6s 3.6 104 280 DFIG 45.3 9

GE 3.6sl 3.6 111 265 DFIG 47.9 0*

Siemens/Bonus 3.6 3.6 107 200 Induction 46.4 1

Repower 5M 5 126 400 DFIG 46.3 1

Prokon Nord Multibrid 5 116 280 PM Sync 43.4 1 Vestas V903MW, 90m

Siemens Bonus 3.63.6MW, 107m* planned upgrades

27 /June 2009

Enercon E-112/120m,4.5/6MW

Prokon Nord5MW, 116m

Vestas NM110/V120m4.2/4.5 MW

GE 3.6 MW 104/111m Repower 5M 5MW, 126


28/41

Offshore Installation TechniquesEarly Industry Approach

ump ng ac arge to nsta tur nes notdesigned for offshore wind industry

Separate cable-laying vessel additionalship to charter

Turbine access using conventional boat 1m wave height limit.

Learning from Experience

Mayflower Resolution vessel purpose-designed to install offshorewind turbines and infrastructure

Transports turbines, towers, blades to foundation and erects

Capable of laying cables

Specially-designed Windcat turbine access craft allows installationand commissioning to continue in strong sea-states (2.5m waveheight)

Going Deeper

Floating platforms / turbines can be assembled at a port

Tugs to take assembly to wind farm location

28 /June 2009

ecure y a ac e o anc or ng po n s


29/41

Foundation Technologies

0 20m : Mono ile & ravit foundations are most

Jacket weight increases

with depth even at

constant MW rating

prevalent; Resonance constraints from rotoroperation leads to increasing tonnage &manufacturing limits.

.Depth dependence on weight

can be reduced substantially

with a floating foundation

system

Gravity FoundationNear Shore

Monopile20 m, 12 km

20 40m: Multi-legged jacket/tripod/braced pilestructures from O&G industry experience. JointFatigue & O&M issues are main design drivers.

40m beyond : Floating Platforms: Mini-TLP / Sparbuoy based platforms under investigation; Primary

29 /June 2009

-dependence from water depth.


30/41

Monopile Foundation System Design Drivers

Modal Analysis - 3.6s/sl Tower/Foundation2

2nd Mode Desi n Box :

1.2

1.6

(Hz)

6P +/-10%

(2X BladePass Freq )

15.3r

pm

1440rpm

erator

in=8. 5

rp m

r,800rp m

enerat o

r

Nmax

=21

.3rpm

r otor,20 0

0rpm

gen

era

tor

f1 >1.607

0.8

Frequenc

3P +/-10%

(Blade Pass Freq

Nrtd

rotor,

ge

Nmi

rot g

0

0.41P +/-10%

(Rotor Pass Freq

1st Mode Design Box: 0.28< f0>0.383n = rotor speed

nR = Ratedrotor speed

Note: Range for f1 depen d s on chosen rated rpm

. . . . . .

Relati ve Rotor Speed (n/n R)

30 /June 2009

Eigen Frequency Often Primary Driver for Monopile Designs


31/41

Nysted Rdsand

31 /June 2009

Source: http://www.aarsleff.com/internet/acms.nsf/Webpages/168241DB8B190997C1256D2B0029822E

-


32/41


33/41

Electrical BOP

Radial 33 kV col lector s stem

, ,

maintenance and 20 year design life.

Need shelter in case someone gets stranded on the platform.

High capacitances of sea cables - reactive compensation and

regulation can play a substantial role in system design.

Transmission

Connection

xxxx

x x x

CBs

33kV

Collector ESP(500MW block)Collector Circuits

1-7

8-14

15-21

22-28

x x

400kV

Shore Connection(500MW block)

x x132kV

x xCB

132kV

System Layout for 500MW UK Farm

BOP Estim ate

Equipment Cost Total

x Transformer Disconnect/Earthing Switch

-

77-84Disconnect/

Earthing Switch

Transformer

Horns Rev 180 MW ESP

500 MW ESP (electrical equipment) $12,925,000

500 MW ESP (platform) $32,075,000 $45,000,000

33 kV Cable (84 miles) $25,000,000

33 kV Cable installation and burial (84 miles) $33,000,000

115 kV Cable (8 miles submarine, 6 miles land) $64,000,000

33 /June 2009

a e - ns a su mar ne , , , ,

Total $188,000,000

Transmission Options, UMass


34/41

UK Offshore 500MW Farm Thames Estuary

Assumptions

Next-gen turbines: 4, 5, 6, or 7 MW

Swept Area: 2.6 m2/kW (approx. same as 3.6sl)

Specific Weight: 55 kg/kW

Tip clearance to water: 25m

Soil Profile from GunFleet Sands 12 m water depth, 20 km to shore

90 m/s tip speed

4 MW 5 MW 6 MW 7 MW# Turbines 125 100 83 71Rotor (m) 116 130 142 153.5

Hub Height (m) 83 90 96 102

Model Inputs

UK economics structure w/ 10.25 c/kWhr

Tower Top Mass (tonnes) 220 275 330 385

Yield (MWhr) 15600 19500 23400 27650

Capacity Factors 44.5% at Gunfleet 9.3m/s at 78m

After Tax Unlevered IRR = 9.5%

Foundation & Tower costs f(MW size)

Civil installation costs f(MW size)

Electrical BOP costs f(MW size)

ModelOutput

Wind Farm Price/MW f(MW

Size)

34 /June 2009

CSA costs f(MW size)


35/41

Economics of 500 MW Offshore Wind Park

ssump ons

Nextgenturbines:4,5,6,or7MW

SweptArea:2.6m2/kW

SpecificWeight:55kg/kW

.

1400

1450

Cost($)

2.80

2.90

MW

Tipclearancetowater:25m

ThamesEstuary

12

m

water

depth,

20

km

to

shore

90m/stipspeed1200

1250

1300

indfarmC

apital

2.40

2.50

2.60

.

CapitalC

ostpe

($/MW)

InstallationCosts

vs

ElectricalBOPCostsvsTurbineRating

$170M

$180M

$190M

PCost

1150

4 5 6 7

Turbine Rating (MW)

2.30

500MW Wind Farm Breakdown

$1.2B Total w/ 5MW Turb ines

35%

12%

Turbines

Foundation Costs vs Turbine Ratin

ur ne a ng

$160

$180

$200

$220

$MM

$150M

$160M

3 4 5 6 7 8

TurbineMW

BO

12%

15%

CSAConstruction & Installation

BOP Electrics

Project Other

550

600

650

700

750

800

850

900

950

1000

Cost(K$)

60

80

100

120

140

160

180

200

FabCost(K$/MW) $100

$120

3 4 5 6 7 8

35 /June 2009

10%

400

450

500

GE 4 MW uni t GE 5 MW un it GE 6 MW un i t GE 7 MW un i t

0

20

40


36/41

GW Scale Wind

10 MW Turbines 180 m rotor diameter

ownw n a e mac ne

Flexible compliant blades Flow control blades

g rpm p ve oc y > m s

Space frame structure

Multivariable damping controls m wa er ep oun a on

Hurricane ride-thru capability

EU Upwind R&D ProgramCan the economics work?

36 /June 2009


37/41

Wind Energy

Cornell une

JP Lyons - CTO Novus Energy Partners

20% US Wi d Vi i


38/41

20% US Wind Vision 2030 DOE, AWEA, 20% Energy Roadmap

Black & Veatch US Wind Supply Curve

300+ GW, 15% CAGR, 25 years

$60B investment in Transmission

Benefits (2030):

- 50% reduction NG electric gen

- 18% reduction in coal gen

- 7500 MMTCE cumulative carbon reduction

- 17% water use reduction for west generation

- 150,000 direct jobs created

Great Plains Wind,

38 /June 2009

US Wind Resource

Hi h P t ti Wi d B d 10%


39/41

High Penetration Wind Beyond 10%

--+

Vref(from gridoperator)

Ihs [AB]

Line Drop Compensation

Vhs

Vhs max

Verror

-

HighSide VoltageLimiter

QB up

(MVAr)

Vhs ref

Vhs min

Vhs

-Qi(to NWTGs)

VoltageRegulationMode

-

Y

switchdelay(for sim.model)

deadbandRegulation

ModeSelection

Qtotal

Qshunt

Qwtgnet

from SCADA:NWTGs on-line

N

++

+

Qmax

= Bma

+ N*Qimax

Qmin=B min+ N*Qimin

anti-windupon Qmax/min

PFAref

(from grid

operator)

Ihs[AB]

PFCalculation withLineDropCompensation

Vhs

+

+

PFAc

- PFAerr

anti-windupon Vhs max/min

Power Factor Regulation Mode

Kppf+Kipf/s

1N

1s

IfQerr1 >0then

out=Qerr1elsereset

integrator

Qerr1 out

reset

IfX 1 >MSC/R tol

thendisconnect

LorconnectC

SwitchedLorC?

X1

reset

-

++

QB down

(MVAr)

IfQerr2 < 0 If X2


40/41

ISO

Timers)

Operation Process Issues

Unit Dispatch

600

700

1 Year

Lines

Slower(Yea Resource and

Capacity Planning

(Reliability)0

100

200

300

400

500

0 2000 4000 6000 8000

Hour

MW

(UCAP, ICAP)

andLong-Term Load

Growth Forecasting

Unit Commitmentand

Day-ahead and-

2001 Average Load vs Average Wind

20,000

25,000

30,000

ad(MW)

1,000

1,200

1,400

1,600

ut(MW)

1 Day

Day-AheadScheduling

Forecasting

e

Frame

0

5,000

10,000

15,000

1 6 11 16 21

Hour

NYISOLo

0

200

400

600

800

WindOut

July load August load September load

July w ind August w ind September w ind

3000

Load Following(5 Minute Dispatch)

Ti

Hour-AheadForecasting

andPlant Active PowerManeuvering and

Management500

1000

1500

2000

2500

MW

3 Hours

Frequency andTie-Line Regulation(s

econds)

Real-Time andAutonomo us Pro tection

and Control Functions

0

1 61 121

M in u t e s

S ep tem ber M or ni ng A u gu st Mo rn ing M ay E ve nin g Oc tob er Ev en in g A pr il A f te rn oon

10 Minutes

40 /June 2009

(AGC)

Faster (AGC, LVRT, PSS,

Governor, V-Reg, etc.)

References


41/41

Wind Energy Handbook

References

, , , Hardcover: 642 pages ; Dimensions (in inches): 1.58 x 9.82 x 6.70

Publisher: John Wiley & Sons; ISBN: 0471489972; 1st edition (November 15, 2001)

Windturbines: Fundamentals, Technologies, Application and Economics

by Erich Hau Hardcover: 650 pages

Publisher: Springer Verlag; ISBN: 3540570640; (April 30, 2000)

by Robert Harrison, Eric Hau, Herman Snel Paperback: 200 pages ; Dimensions (in inches): 0.57 x 10.86 x 8.66

Publisher: John Wiley & Sons; ISBN: 0471494569; (January 2001)

Wind Energy Explained

by J. F. Manwell, Jon McGowan,Anthony Rogers Hardcover: 512 pages ; Dimensions (in inches): 1.49 x 9.88 x 6.64

Publisher: John Wiley & Sons; ISBN: 0471499722; 1st edition (June 15, 2002)

Grid Integration of Wind Energy Conversion Systemsby Siegfried Heier, Rachel Waddington (Translator Hardcover: 250 pages ; Dimensions (in inches): 1.01 x 9.92 x 6.80

Publisher: John Wiley & Son Ltd; ISBN: 047197143X; (September 1998)

41 /June 2009

lyons (wind energy systems)

Documents