Prof. Alessandro Croce - polimi.it

Impianti Eolici: introduzione e definizioni

Prof. Alessandro Croce

Milano, May 2019

Corso di Impianti Eolici: introduzione e definizioni


First of all: (three) basic components of a wind turbine

1. WIND

2. ROTOR

3. ELECTRICAL GENERATOR

Wind power

Mechanical power

Mechanical power

Electrical power



Making Torque from Wind

Horns Rev Wind Farm, Eastern North Sea – Photo © Christian Steiness




Wake expansion

Pressure drop

Pressure rise

Slowed speed due to energy extraction from flow

Incoming wind (fuel)





Wake expansion

Pressure drop

Pressure rise

Slowed speed due to energy extraction from flow

Torque

Incoming wind (fuel)


Wake swirl



HAWT VS VAWT

► TN420 Tozzi Nord(source: http://www.tozzinord.it/)

► TN1.5 Tozzi Nord(source: http://www.tozzinord.it/)



HAWT VS VAWT

► Éole Cap-Chat 4MW, 110m (source: http://www.eolecapchat.com/e_index.html)



HAWT VS VAWT

► Innovative Offshore Vertical-Axis Wind Turbine Rotors (source:http://energy.sandia.gov/energy/renewable-energy/wind-power/offshore-wind/innovative-offshore-vertical-axis-wind-turbine-rotors/)



Anatomy

GENERATOR

PITCH ACTUATOR

BLADE

TOWER

NACELLE

YAW BEARING

DRIVE TRAIN SHAFT

HUB

(picture source: GE)

PITCH BEARING



Blade

► LM Glasfiber LM 37.35590kg (1-1.5MW)

► LM Glasfiber LM 61.518841kg (5MW)

(source: LM Glasfiber)

(source: LM Glasfiber)

(source: poliwind.org)



Blade

► Siemens B75 75m (6MW)

(source: siemensgamesa.com)



Blade

► SPP 83.5m~30tons (for Samsung's S7.0 171 7MW offshore turbine)

(source: ssptech.com)



Blade► LM Wind Power 88.4m

(source: lmwindpower.com)



Blade

► GE Haliade-X 12MWLM Wind Power 107m

(source: genewsroom.com & lmwindpower.com )

(source: genewsroom.com)



(sources: reuk.co.uk, geograph.org.uk, coriolis-energy.com, windpowerengineering.com)

Gearbox



(sources: wind-energy-the-facts.org, scruss.com, windpowerengineering.com, inhabitat.com, leitwind.com, innwind.eu)

Direct-Drive Configurations



(sources: Clipper Windpower, wind-energy-the-facts.org, eetweb.com, machinedesign.com)

Hybrid Concepts



► Bosch Rexroth(Yaw Actuator)

► BluMiniPower(Passive Yaw)

►MiniWind 1100-24 (Downwind)

Yaw Control

►Seawind 6(Yaw Control)

(sources: boschrexroth.com, stonewindsolar.co.uk, assorinnovabili.it, norcowe.no)



Fuhrländer AG FL2500 ►(lattice tower, h=160m)

▲ Leitwind LTW-62(steel tower, h=58m)

▲Enercon E-101(concrete tower segments)

Tower

Nordex N131 3.3MW ►(hybrid tower, h=164m)

(sources: poliwind.org, r2controls.com, stonewindsolar.co.uk, commons.wikimedia.org, www.windpowermonthly.com)



Last, but not least… Foundations

(sources: windfarmbop.com)



Foundations

(sources: steelwindtower.com)



Onshore VS Offshore wind farm

▲ Off-shore wind farm (Copenhagen, DK)▲ On-shore wind farm Cocullo (Abruzzo, Italy)

(sources: estremocentrobasilicata.wordpress.com, poliwind.org)



Offshore foundations

(Illustration by Josh Bauer, National Renewable Energy Laboratory (NREL), graphics: poliwind.org)

MONOPILE JACKET TWISTED JACKET

Fixed

SEMI-SUBMERSIBLE TENSION LEG PLATFORM SPAR BUOY

Floating



Offshore foundations

(Source: windpowerengineering.com, seawindtechnology.com, www.energy.gov, StatoilHydro)



How we get here?

8 MW

1970 2016

First attempts by large(mostly aerospace) companiesLockheed, Boeing, Hamilton Standard, Kaman Aerospace, MBB, MAN, Fokker

(from Prof. G. van Kuik)

Pioneers …

… have become world playersWTS-4 (4 MW)

Hamilton Standard, 1982MOD-5B (3.2 MW)Boeing, 1987

10 kW

V164 (8 MW)Vestas, 2016

V10 (30 kW)Vestas, 1979



Unique Aspects: a) Dimensions

In Germany (source: IWES)

Size

Weig

ht

(Cost)

Cubic law of growth

Technological innovation



Unique Aspects: b) Simplicity

Significant differences with respect to aeronautical technology:

• Dimensions: need relatively low cost materials, large volumes

• Reliability/maintenance: performance with simplicity and robustness

• One primary objective: minimize cost of energy

Moving parts, actuators, sensors



Forecasts of reasonable accuracy: 6% 24 h, 2.5% 2h (ISET)

Where the Wind is in Europe



The Energy Mix - EuropeData from 25 February 2019 – Source: windeurope.org/about-wind/daily-wind/



The Energy Mix - EuropeData from 25 February 2019 – Source: windeurope.org/about-wind/daily-wind/

TOTAL [GW] 416.16

Wind Offshore 1.20

Wind Onshore 29.18

Other Renewables 1.31

Solar 28.39

Other 11.51

Hydro 77.51

Gas 76.21

Hard Coal 32.84

Lignite 39.66

Nuclear 105.11

Biomass & Waste 13.25



The Energy Mix - ItalyData from 25 February 2019 – Source: windeurope.org/about-wind/daily-wind/



The Energy Mix - ItalyData from 25 February 2019 – Source: windeurope.org/about-wind/daily-wind/

TOTAL [GW] 37.94 100%

Wind Onshore 5.54 14.60%

Other Renewables 0.65 1.71%

Solar 5.59 14.73%

Other 4.24 11.18%

Hydro 4.40 11.60%

Gas 15.06 39.69%

Hard Coal 1.92 5.06%

Biomass & Waste 0.54 1.42%



https://demanda.ree.es/demandaGeneracionAreasEng.html

Wind 34%

Wind 60%

Wind 22%

The Energy Mix

• Wind energy cannot have the same importance in all countries

• Different countries should aim at different energy mixes, depending on their specific natural resources

• An integrated efficient network enables the management of the energy mix within each country (time of the day/season) and across borders



The mix: annual installed capacity and renewable share in EU-28

Source: Wind energy in Europe in 2018, WindEurope, February 2019



Wind in 2017 was the 2nd largest power generating capacity in the EU

• Total RES = 26%

• Wind power = 6%

EU Power MIX 2005 (GW) EU Power MIX 2017 (GW)

• Total RES = 47%

• Wind power = 18%

Source: Wind in power 2017, WindEurope, February 2018

The power mix: share in installed capacity

EU Power MIX 2000 (MW)

• Total RES = 24%

• Wind power = 2.4%



Share of new installed capacity in 2017 – record year!

New installed capacity: total 28,310 MW New renewable power installations: total 23,926 MW


• Total RES = 84.5%

• Wind power = 55.4%



The mix: Total power generation capacity in the European Union 2005-2017


With a total net installed capacity of 169 GW, wind energy in 2017 remains the second largest form of power generation capacity in Europe, closely approaching gas installations.





With a total net installed capacity of 169 GW, wind energy remains the second largest form of power generation capacity in Europe, closely approaching gas installations.

2007: Wind overtakesFuel Oil

2013: Wind overtakesNuclear

2015: Wind overtakesLarge Hydro

2016: Wind overtakesCoal





With a total net installed capacity of 169 GW, wind energy remains the second largest form of power generation capacity in Europe, closely approaching gas installations.

2007: Wind overtakesFuel Oil

2013: Wind overtakesNuclear

2015: Wind overtakesLarge Hydro

2016: Wind overtakesCoal

FLEX POINT



Gross annual onshore and offshore wind installations in Europe


• 2018 was the lowest year for new onshore installations since 2008

• offshore installation were 16% lower than the record year 2017



National breakdown of wind installations - 2018




National breakdown of wind installations in Europe – 2008-2018




Cumulative wind installations in Europe – 2008-2018


189 GW of wind power capacity are now installed in Europe. 10% of these are offshore. Cumulative capacity grew 6% compared to 2017



Gross installations, decommissioning and cumulative capacity in 2018

EU-28 (MW) NEW INSTALLATIONS 2018 DECOMMISSIONED CUMULATIVE CAPACITY 2018ONSHORE OFFSHORE

Austria 230 - 29 3,045 Belgium 204 309 - 3,360 Bulgaria - - - 691 Croatia - - - 583 Cyprus - - - 158 Czechia 14 - - 317 Denmark 220 61 13 5,758 Estonia - - - 310 Finland 0 - 3 2,041 France 1,563 2 13 15,309 Germany 2,402 969 249 59,311 Greece 207 - 15 2,844 Hungary - - - 329 Ireland 193 - - 3,564

Italy 452 - - 9,958 Latvia - - - 66 Lithuania 18 - - 439 Luxembourg - - - 120 Malta - - - -Netherlands 166 - 72 4,471 Poland 16 - - 5,864 Portugal 67 - 14 5,380 Romania - - - 3,029 Slovakia - - - 3 Slovenia - - - 3 Spain 392 5 - 23,494 Sweden 717 3 13 7,407 UK 589 1,312 - 20,970

Total EU-28 7,450 2,661 421 178,826


Other EU (MW) NEW INSTALLATIONS 2018 DECOMMISSIONED CUMULATIVE CAPACITY 2018ONSHORE OFFSHORE

Bosnia and Herzegovina 51 - - 51 Kosovo 32 - - 32 Montenegro 46 - - 118 North Macedonia - - - 37 Norway 480 - - 1,675 Russia 35 - - 139 Serbia 356 - - 374 Switzerland - - - 75 Turkey 497 - - 7,369 Ukraine 68 - - 533

Total others 1,566 - - 10,403

Total Europe 9,015 2,661 421 189,229



Wind power installed in EU - 2018




… and in the World

Source: GWEC Global Wind Report April 2018 Final



… and in Italy?

(source: IEA Annual report 2015)

• A decrease in new added capacity was experienced since 2013 due to the new incentive mechanism introduced on 1 January2013;

• Wind electricity generation decreased from 15.1TWh (2014) to 14.6TWh (2015) (corresponds to 4.6% of total electricitydemand);

• As in previous years, most of WTs were supplied by foreign producers;

• In 2015 a considerable number of small wind turbines (under 200 kW) were installed. About 50MW are from 2000 small WTs.



windeurope.org

gwec.net

Further Information

poliwind.org

eawe.eu



Basic concept: power coefficient




1D Momentum Theory

Ain,rin

VinVoutVD

AD,rD

Aout,rout

inlet section rotor disc section outlet section




1D Momentum Theory

Ain,rin

VinVout

Aout,rout

AD

ሶ𝑚 ሶ𝑚

Ain

VD

AD,rD

Detailed mathematical model will be faced in the rotor aerodynamics classes




1D Momentum Theory

Ain,rin

VinVout

Aout,rout

AD

ሶ𝑚 ሶ𝑚

Ain

ሶ𝑚 = 𝜌𝑖𝑛𝐴𝑖𝑛𝑉𝑖𝑛 = 𝜌𝐷𝐴𝐷𝑉𝐷Mass flow rate

VD

AD,rD




Available kin. energy:

Reference kin. energy:

Power coefficient (hence not a real efficiency)

So that aerodynamic power

𝐸𝐾 =1

2ሶ𝑚𝑉𝑖𝑛

2 =1

2𝜌𝑖𝑛𝐴𝑖𝑛𝑉𝑖𝑛

3

𝐸0: =1

2𝜌𝑖𝑛𝐴𝐷𝑉𝑖𝑛

3 = 𝐸𝐾𝐴𝐷𝐴𝑖𝑛

𝐶𝑃: =𝑃𝐴𝐸0

𝑃𝐴 =1


3𝐶𝑃

𝐶𝑃 = 𝐶𝑃(λ)

𝜆 ≔Ω𝑅

𝑉

Where:

• r0 constant (M<<1)

• Vin farfield flow velocity;

• AD rotor disc area;

• Cp (non-dimensional) power coefficient

Being l=TSR

𝜌0 = 𝜌

simplifying the notation: 𝑃𝐴 =1

2𝜌𝐴𝑉3𝐶𝑃




Available kin. energy:

Reference kin. energy:

Power coefficient (hence not a real efficiency)

So that aerodynamic power

𝐸𝐾 =1

2ሶ𝑚𝑉𝑖𝑛

2 =1

2𝜌𝑖𝑛𝐴𝑖𝑛𝑉𝑖𝑛

3

𝐶𝑃: =𝑃𝐴𝐸0

𝐶𝑃 = 𝐶𝑃(λ)

𝜆 ≔Ω𝑅

𝑉

Where:

• r air density

• V farfield flow velocity;

• A rotor disc area;

• Cp (non-dimensional) power coefficient

Being l=TSR (Tip Speed Ratio)

𝑃𝐴 =1


𝐸0: =1


3 = 𝐸𝐾𝐴𝐷𝐴𝑖𝑛





Ctorque≠0 Ctorque=0 CP=0 ↔ l=0 or Ctorque=0

𝐶𝑝𝑜𝑤𝑒𝑟 = 𝜆𝐶𝑡𝑜𝑟𝑞𝑢𝑒





CP=CP ( l) presents a max value!

i.e. a TSR where the rotor extract the maximum energy from the wind (for this pitch actuation…)



Basic concept: power coefficient. Example

Hp1:

• Wind Turbine Pnameplate =1MW (aerodynamic power, no losess here);• CP = 0.5;• Vrated = 10m/s (low value, but in IT mean wind ≈7m/s);• ISA, h=0, (r=1.225Kg/m3);

Hp2: • Vrated = 12m/s (standard value);

► Diameter D2 = 49.0m

Note: no control law, no stall effect. Only torque control (i.e. rotor speed control) @ TSRmaxCp




Hp1:






𝑃𝐴 =1





Hp1:






𝑃𝐴 =1


𝑃𝐴 =1





case 1 (D=64m)

case 2 (D=49m)

@ 7m/s (mean value in IT): P1=343kW , P2=199kW

@ 15m/s: P1=3.3MW , P2=1.9MW

𝑃𝐴 =1





case 1 (D=64m)

case 2 (D=49m)

@ 7m/s (mean value in IT): P1=343kW , P2=199kW

@ 15m/s: P1=3.3MW , P2=1.9MW

Site Selection & CoE Evaluation!

Need Control!

𝑃𝐴 =1




windeurope.org

gwec.net

Further Information

poliwind.org

eawe.eu

Prof. Alessandro Croce - polimi.it

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