Vindkraft i kraftsystemet

SINTEF Energiforskning AS 1

Vindkraft i kraftsystemet

Kjetil Uhlen og John Olav G. Tande

SINTEF Energiforskning

[email protected]

[email protected]

mailto:[email protected]

mailto:[email protected]


Oversikt

Vindkraftteknologi

Styring og kontrollmuligheter

Systemutfordringer

Eksempler:

Balansehåndtering

Energi- og effektbidrag

Storskala offshore vindkraft - systemkonsekvenser


Norwegian wind energy potential

Very good wind conditions – wind farms may produce +3000 full load hours

Theoretical potential +1000 TWh/year (annual el consumption in Norway ~120 TWh)

Official target is 3 TWh annual wind energy production by year 2010

Development is ongoing: 320 MW (~1 TWh) was installed by mid 2006; +15 TWh is in planning

Financial support is low: 0.08 NOK/kWh and probably not sufficient for many projects

A realistic goal for wind energy use in Norway is 20 TWh by 2020 (on land and offshore)

Norway has also a potential for developing a wind industry – especially related to deep sea offshore technology.

Smøla 150 MW wind farm


Oversikt

Vindkraftteknologi


Systemutfordringer

Eksempler:

Balansehåndtering




From wind turbines to wind power plants

1980’s: typical wind turbine size 50 - 300 kW

few installations – marginal influence on distribution grids

grid connection was allowed using simple rule of thumbs

1990’s: typical wind turbine size 300 – 1500 kW

more and larger installations – significant impact on voltage quality

national guidelines suggest limits for flicker emission etc, and that WTs shall stop in case grid conditions outside 0,9<U<1,1 pu and 48<f<52 Hz

IEC 61400-21 (ed 1 – 2001) gives basis for rational assessment of impact on voltage quality of wind turbines in distribution grids

2000’s: typical wind turbine size is in MW’s

large wind farms constitute significant part of power system

grid codes require wind farms to ride-through temporary grid faults, and also support voltage and frequency control

wind farms are becoming power plants - IEC 61400-21 is updated accordingly to facilitate power quality test on modern wind turbines


Teknologi - Vindkraftverk

Horisontalakslede (tre-bladede) vindturbiner for kraftproduksjon Elektromekaniske konfigurasjoner

Regulering

Foto: Hydro


Main types of wind turbine technologies

Fixed speed, stall/pitch

Full converter, gear/no gear

Doubly-fed induction generator

Gear box IG

Control system

Gear box IG

Control system

Gear box G

Control system ~~

Gear box G

Control system ~~

Gear box DFIG

Control

system ~~

Gear box DFIG

Control

system ~~~

~

Variable slip

Gear box

Control system

Gear box

Control system

Total wind technology market ~ EUR 12 billion (2005)

Top 5 manufacturers: Vestas, Enercon, Gamesa, GE, Simens


Major wind turbine manufacturers Vestas (DK)

Opti-slip and Opti-speed

NTE: Vikna og Hundhammerfjellet

SIEMENS-BONUS (DK)

Traditional AG/active stall

Statkraft: Smøla (150 MW), Hitra (55 MW) and Kjøllefjord

Enercon (DE)

Multi-pole synchronous generator, direct drive

TE: Valsneset and Bessakerfjellet

Nordex (DE)

DFIG

Havøygavlen: 16 x 2.5 MW

GE wind (USA)

DFIG og frequency converter

ScanWind (N)

NTE: Hundhammerfjellet


Slik kan de se ut..

Stator i Enercons 4.5 MW

Her mangler det et bilde av

en ”konvensjonell”

vindturbingenerator

Vestas V80-2MW nacelle


Oversikt

Vindkraftteknologi


Systemutfordringer

Eksempler:

Balansehåndtering




Reguleringsformål

Maksimal utnyttelse av tilgjengelig

vindenergi

Følge driftsoptimum.

Redusere belastninger

Aktiv demping av mekaniske svingemodi.

Bidra i systemsammenheng

Effekt, frekvens og spenningsregulering


Regulering av vindkraftverk

Hensikt:

Optimalisering av elproduksjon

Effektbegrensning

Redusere effektfluktuasjoner og mekaniske påkjenninger, pga:

Hurtige vindvariasjoner

Strukturelle modi, 3P-variasjoner, osv.

(Forstyrrelser fra nettet)

Overholde krav til elkvalitet

Dempe effekten av hurtige vindvariasjoner på spenning.

Redusere flimmer

Reaktiv støtte / spenningsregulering


Additional wind farm controls

Control of power output from wind farm.

Setpoint control within the available power range

Frequency and voltage control

Control functionality enabling wind farms to

contribute with primary active and reactive

reserves


Modern wind farm control

Time

Pow

er

Set-point power

Available power

Frequency

Pow

er

droop

Voltage

Reactive p

ow

er

droop

Time

Reserve power

Available power

Pow

er


Energi og effekt i vinden

Betz-Lanchester: For en ideell rotor Cpmax=0.59 hvis

31

2 windwind p air rotorP C A v

Turbineffekt:

www.windpower.org

1

2

3v

v

Typiske verdier for effektkoeffisient for trebladede vindmøller

ligger i dag omkring Cp=0.5.

Effektfaktoren er avhenging av: - Antall blader i rotor.

- Blad – design.


Regulering av vindkraftverk

Effektregulering

Mulighetene avhenger av systemkonfigurasjon

(turbin og el-konverteringssystem)

Prinsipper for effektregulering:

”Stall”

”Pitch”

Turtall

Vha. frekvensomformer

Vha. asynkrongenerator og variabel sakking

”Yaw”


Turbineffekt:

PW = ½ Cp(l ,b ) A vw3 ,”Tip speed ratio” l = w r / vw

- Turtall

- Pitch

- Yaw

Gear-

box Nett

PW vw

Pel

w f1 f2

b


Effektregulering

Variabelt turtall

Begrensninger i pitch-regulering knyttet til hastighet

(båndbredde) og ytelse.

Ved å regulere turtall oppnås:

Ytterligere optimalisering av virkningsgrad.

Kan utnytte energien i roterende masser (korttids energilager).

Hurtigere og nøyaktigere regulering

Turtallsregulering kan implementeres på ulike måter

vha. asynkrongenerator med variabel sakking

vha. dobbeltmatet asynkrongenerator

vha. full frekvensomformer (uavhengig av generator)


Oversikt

Vindkraftteknologi


Systemutfordringer

Eksempler:

Balansehåndtering




Hva er systemutfordringene?

(Økonomi og pålitelighet)

Driftssikkerhet Risiko mht utfall/blackouts (pålitelighet, spenningskvalitet)

Overvåking og kontroll i drift

Tekniske og funksjonsmessige krav til anlegg som tilknyttes nettet

Effektbalanse Risiko for effektsvikt (rasjonering, osv.)

Driftsplanlegging

Balansehåndtering

Energiplanlegging Risiko for energimangel (høye priser)

Langsiktig planlegging og investering i nett og produksjon



Exchange capacity (MW)

NORWAY

DENMARK

SWEDEN

FINLAND

600 MW= 600 MW= <1200 MW

1050 MW=

1350 MW

740 MW=

270 MW=

500 MW

2000 MW

200 MW

740 MW

600 MW=

1600 MW 1200 MW

100 MW

700 MW=

350 MW=

EST

POL

GER NED

500 MW=


Large scale integration of

renewable energy:

• Positive contribution to the

energy balance

• Main challenges:

– Market solutions

– Bottlenecks and

transmission capacity

– Voltage and frequency

control and support

– Failure tolerance and

protection (FRT)

– Reactive power support

Source: Statnett Current challenges


Hva skiller vindkraftverk fra andre kraftverk?

Vindkraftverk mangler energilager ”bak” turbinen

Vanskeliggjør produksjonsplanlegging

Nett G Energi input:

-Brensel

-Magasin

Aktiv effekt

Frekvens

Spenning

Reaktiv effekt

Nett vw

G Energi input:

-Vind

Aktiv effekt

Frekvens

Spenning

Reaktiv effekt


Uregulert produksjon?

Begrep fra vannkraft

Kraftverk med liten eller ingen magasinkapasitet (elvekraft)

Karakterisert ved

at kraften må produseres når det er tilsig

mindre frihetsgrader mht produksjonsplanlegging

Definisjonen passer også godt for vindkraft

Og i noen grad for kombinerte kraft- og varmeverk (CHP)

Uregulert kraft betyr

at energitilgangen er variabel og ikke fullt styrbar

Ikke at produksjonen er uforutsigbar


Annual and seasonal wind generation

0

20

40

60

80

100

120

140

1960 1965 1970 1975 1980 1985 1990 Year

Normalised annual production (%)

Wind Hydro

0

1

2

3

4

5

6

7

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 Week of year

(% of annual)

Wind Power

Hydro inflow

Consumption

Wind and hydro – a win-win case:

Combining wind and hydro provides for a more stable annual energy supply

than hydro alone, and wind generation will generally be higher in the winter

period than in the summer.


0 5 10 15 200

0.05

0.1

0.15

0.2

0.25

# of sites

Std

of

delt

a w

ind

po

wer

(pu

)

Estimate

Observation

Hour by hour variations of wind generation

Wind impact on need for balancing power:

10 % wind energy supply of gross demand in the Nordic power system

gives an extra balancing power of 1.5%-4% of the installed wind capacity,

corresponding to a cost of about 0,8 øre per kWh wind, and about half if

investment in new reserve capacity is not needed. [Holttinen 2005]


Wind capacity value

0 200 400 600 800 10000

50

100

150

Installed wind power (MW)

Ca

pa

city v

alu

e (

MW

) a)

0 200 400 600 800 100010

20

30

40

Installed wind power (MW)

Ca

pa

city v

alu

e (

%) b)

0 2 4 6 8 10 12 1410

20

30

40

Penetration level (%)

Ca

pa

city v

alu

e (

%) c)

Simple scaling of wind production

Summation of three wind farms

Wind capacity value = average generation at low penetration

The smoothing effect of distributed wind is significant


Wind generation impact on power system

Wind will replace the generation

with the highest operating cost,

and reduce the average Nord

Pool spot market price.

20 TWh/y wind generation will

reduce the average system price

with about 3 øre/kWh and CO2

emissions by 12-14 million tons

per year for the case of replacing

coal, and about 6 million tons per

year for replacing natural gas.

Replacing gas turbines on oilrigs

with wind generation would give

higher savings of CO2 and NOx

emissions.

MWh

NOK/MWh

Supply (sale)Demand (buy)

System price

Volume


Oversikt

Vindkraftteknologi


Systemutfordringer

Eksempler:

Balansehåndtering




Example related to congestion management and

balancing control in Nordel

Frequency control reserves

Balancing control

Congestion management

Reserves

Illustrating Nordic collaboration and sharing of reserves across synchronous interconnections (UCTENordel)

Example is from 8. January 2005 nearly 2000 MW wind power disconnected due to severe storm in

Southern Scandinavia


Denmark West

Key counts of the power system of Eltra for the year 2003

(Source: Energinet.dk)

MW GWh

Central power plants 3,516 16,161

Decentralised CHP units 1,567 6,839

Decentralised wind turbines 2,374 4,363

Offshore wind farm Horns Rev A 160

Consumption 21,043

Maximum load 3,780

Minimum load 1,246

Capacity export to UCTE 1,200

Capacity import from UCTE 800

Capacity export to Nordel 1,560

Capacity import from Nordel 1,610


Elspot areas and transmission capacities

NO1

DK1

SE

NO2 FI

To Germany

DK2

950 MW 1000 MW

800 MW 1200 MW

NO3


Real life case – balance handling

NO1

DK1SE

NO2FI

Germany

800/1200 MW

DK2

+/-1000 MW

670/630 MW

Data for DK1, west Denmark 2003 MW

Central power plants 3,516

Decentralised CHP units 1,567

Decentralised wind turbines 2,374

Offshore wind farm Horns Rev A 160

Maximum load 3,780

Minimum load 1,246

At 8 January 2005 a strong storm crossed

over Denmark

The wind farms of western Denmark at first

produced close to rated power, but then

started to cut out due to the excessive wind

speed (+ 25 m/s) – the wind production were

reduced from about 2200 MW to 200 MW in

a matter of 10 hours


The case demonstrates that the existing marked based mechanisms can

handle large variations in (wind) generation and demand

8 January 2005

-1000

-750

-500

-250

0

250

500

750

1000

1250

1500

1750

2000

2250

2500

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour

MW

h/h

Exchange DK1 -> NO1

Balancing power (NO1)

Windpower DK1

Source: NORDPOOL


Oversikt

Vindkraftteknologi


Systemutfordringer

Eksempler:

Balansehåndtering




Wind impact on system adequacy - Case study

18 TWh annual load / 3180 MW max load

Increasing to 21 TWh / 3780 MW

13 TWh hydro / 2250 MW (6x375 MW)

Total import capacity

14 TWh / 1600 MW (4x400 MW)

0,18 TWh wind / 62 MW (3 wind farms)

Options

A: 3 TWh wind / 1000 MW (3 wind farms)

B: 3 TWh gas / 375 MW

C: 3 TWh wind + 3 TWh gas


Normal year load and generation

0

5000

10000

15000

20000

25000

30000

35000

Base (1.0 %) A (15.2 %) B (0.9 %) C (15.2 %)

GW

h

Import

Gas

Wind

Hydro

Load


Base case 30 years week by week import

(result of Multi-Area Power Market Simulation)

-300

-200

-100

0

100

200

300

400

1 6 11 16 21 26 31 36 41 46 51

Week of year

Imp

ort

pe

r w

ee

k (

GW

h)


Cumulative distribution of weekly import

0

10

20

30

40

50

60

70

80

90

100

-400 -200 0 200 400

Import per week (GWh)

CD

F o

f im

po

rt (

%)

Base

Case A

Case B

Case C


Annual variations in import

-4000

-2000

0

2000

4000

6000

8000

10000

1961 1966 1971 1976 1981 1986

Year

Imp

ort

(G

Wh

)

Base

Case A

Case B

Case C

Wind and gas contributes equally to the energy balance


Case study max load and generating capacity

0

1000

2000

3000

4000

5000

6000

Base A B C

MW

Wind

Gas

Import

Hydro

Max load


Loss of load probability (LOLP)

Base A B C

LOLP (%) 0.11 7.2 1.43 0.35

Wind capacity value (%) 31.5 14.7 34.3 13.6

Gas capacity value (%) - - 95.2 94.7

Wind penetration (%) 1.0 15.2 0.9 15.2

Without new generation in case A, B and C the LOLP=26%

LOLP is here probability of exceeding N-1 criterion

Capacity value = load carrying capacity


Oversikt

Vindkraftteknologi


Systemutfordringer

Eksempler:

Balansehåndtering




Integration of large-scale offshore

wind power in the Norwegian power

system

Magnus Korpås, Thomas Trötscher,

John Olav Giæver Tande SINTEF Energy Research

[email protected]


Project: Deep sea offshore wind power

Installation at deep sea far from shore:

Unlimited potential and high energy output

Minimized negative environmental impact

Challenges:

Bigger, lightweight and strong wind turbines

Foundation / floater

Grid connection (AC, HVDC, multi-terminal)

Grid connection and power system

integration

HYWIND


Use Norwegian oil and gas industry know-how.

Large scale commercial use of floating offshore wind turbines is

viable by year 2020.

The market is global.

Hot political subject in Norway.

25 TWh/y wind generation for supply to oilrigs, mainland grid and trans-national connections

Floating offshore wind turbines –

a sustainable energy future


Simulation study

5 simulation cases describing possible situations in

2025:

A: 10 TWh load increase

B: …added 25+10 TWh offshore+onshore wind

C: …added 20 TWh new hydro

D: …added new wind in DE and DK

E: …added 3200 MW new exchange capacity


Wind data

1000 2000 3000 4000 5000 6000 7000 80000

0.2

0.4

0.6

0.8

1

Duration [hours]

Norm

alised p

roduction [

p.u

.]

Estimated 5 offshore wind farms, NO

Estimated 5 onshore wind farms, NO

Historical onshore, DK-W

3oE 6oE 9oE 12oE 15

oE

57oN

60oN

63oN

66oN

LISTA FYR

UTSIRA FYR

KRÅKENES

ONA II

NORDØYAN FYR

MYKEN

0.5 1 1.5 2 2.5 3 3.5 4

x 104

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

Hours

p.u

. of

insta

lled p

ow

er

LISTA FYR

UTSIRA FYR

KRÅKENES

ONA II

NORDØYAN FYR

MYKEN


Power market model


Wind impact on hydro reservoir

1000 2000 3000 4000 5000 6000 7000 80000

10

20

30

40

50

60

70

80

90

100

Time [hours]

Reserv

oir level [%

]

1000 2000 3000 4000 5000 6000 7000 80000

10

20

30

40

50

60

70

80

90

100

Time [hours]

Reserv

oir level [%

]

A: 10 TWh load increase B: Added 25+10 TWh wind

Median 2005 reference

Median


Wind impact on prices

2 4 6 8 10 12 14 16 18 20 220

200

400

600

800

1000

1200

1400

Hydro inflow year

NO

price [

NO

K/M

Wh]

Reference case

Case A: 15 TWh load increase

Case B: Added 35 TWh wind

Wind reduces winter price peaks in dry years


Wind impact on prices

0 10 20 30 40 50 60 70 80 90 1000

200

400

600

800

1000

1200

1400

Duration [%]

NO

price [

NO

K/M

Wh]

A

B

C

D

E

load increase

add wind in NO

add hydro in NO

add wind in DE+DK

3200MW new HVDC

Hours with zero price caused by full hydro reservoirs


Wind impact on power exchange

2 4 6 8 10 12 14 16 18 20

-30

-20

-10

0

10

20

30

40

50

60

Hydro inflow year

Net

export

fro

m N

orw

ay [

TW

h/y

r]

A B C D E


Conclusions

Deep sea offshore wind power has very high potential in Norway

Unlimited areas

Very high wind speeds

Wind power relieves constrained energy situations in winter

Adding 25 TWh offshore wind, 10 TWh onshore wind and 20 TWh

hydro is a plausible scenario

Exchange capacity should be increased to avoid hydro spillage


Further work

Include year-to-year variations in wind speed

Increase number of price areas

Further tuning of water-value calcualtions

Analysis and optimization of offshore grid layout


3oE 6oE 9oE 12oE 15

oE

57oN

60oN

63oN

66oN

LISTA FYR

UTSIRA FYR

KRÅKENES

ONA II

NORDØYAN FYR

MYKEN


1000 2000 3000 4000 5000 6000 7000 80000

0.2

0.4

0.6

0.8

1

Duration [hours]

Norm

alised p

roduction [

p.u

.]

Estimated 5 offshore wind farms, NO

Estimated 5 onshore wind farms, NO

Historical onshore, DK-W


0.5 1 1.5 2 2.5 3 3.5 4

x 104

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

Hours

p.u

. of

insta

lled p

ow

er

LISTA FYR

UTSIRA FYR

KRÅKENES

ONA II

NORDØYAN FYR

MYKEN


Summing up:

Wind generation impact on power system operation and adequacy will be overall positive. Wind contributes with energy and capacity value.

Combining wind and hydro provides for a more stable annual energy supply than hydro alone, and wind generation will generally be higher in the winter period than in the summer.

Wind impact on the need for additional balancing power is moderate, i.e. the extra balancing cost is about 0,8 øre per kWh wind, and about half if investment in new reserve capacity is not needed.

The real life example from 8 January 2005 demonstrates that existing market based mechanisms can handle large amounts of wind power

Wind power has a capacity value starting from average power and decreasing at high penetration

35 TWh wind will reduce the average spot market price with about 5-8 øre/kWh.

Wind generation is a cost-effective means to reduce emissions of greenhouse gasses

Impact of integrating wind power in the Norwegian power system

SINTEF Energy Research, April 2006, TR A6337. www.sintef.no/wind


Nordic power system

Power system (see www.nordel.org):

Synchronous Nordic interconnection: Norway, Sweden, Finland and Denmark East

Denmark West is synchronously connected to UCTE

Iceland

Main players:

Power exchange: NordPool

TSOs: Statnett (NO), SvK (SE), Fingrid (FI) and Energinet.dk

DNOs, generators, consumers, traders, etc.

http://www.nordel.org/


Nordic power system

Markets and services (see www.nordpool.com): Financial market and clearing services

Hourly day-ahead market: ELSPOT

Intra-day market ELBAS (individual hours, up to one hour prior to delivery):

Intra-hour/real-time balancing market: RK (Regulating power market) Operated by the TSOs

Some characteristics of the Nordic power system (that motivates present ancillary services): Strong and weak grids, long distance interconnections,

many players,

distributed generation,

high share of hydro power,

close cooperation.

http://www.nordpool.com/


Key figures for 2006

Nordel DK Fin Icel. Nor Swe

Population mill. 24.8 5.4 5.3 0.3 4.7 9.1

Total consumption TWh 405.4 36.4 90.1 9.9 122.6 146.4

Maximum load1 GW 66.8 6.3 14.2 1.1 19.9 25.4

Electricity generation TWh 393.9 43.3 78.6 9.9 121.7 140.3

Breakdown of electricity generation:

Hydropower % 51 0 14 73 98 44

Nuclear power % 22 - 28 - - 46

Other thermal power % 24 86 58 0 1 9

Wind power % 3 14 0 - 1 1

Geothermal power % - - - 27 - -

1) Measured 3rd Wednesday in January - = Data are non-existent 0 = Less than 0,5 %

Source: Nordel


Generation capacity in Nordel (GW)

10.8

2.6 2.9

27.6

0.6

NORWAY

DENMARK

SWEDEN

FINLAND 9.2

3,1

5.0

9.5

16.2

0.5 Conv. thermal

Nuclear

Hydro

Wind

0.3

0.1


Electricity Generation in Nordel 2006 (TWh)

NORWAY

DENMARK

SWEDEN

FINLAND

Conv. thermal

Nuclear

Hydro

Wind

37

6

120

1

13

64 62 46

22 11

1

1


Floating offshore wind turbines

Installation at deep sea far from shore:

Unlimited potential and high energy output

Minimized negative environmental impact

Cost competitive renewable generation

Challenges:

Bigger, lightweight and strong wind turbines (10 MW, 160 m wingspan ~ twice a jumbo jet)

Develop floater (design, installation, O&M)

Power system integration of large scale wind

Key Norwegian industry stake-holders:

ScanWind; large wind turbines

Hydro and Sway; floater concept

Aker Kværner, Nexans, Devold AMT, Umoe Ryving etc; sub-supplies of components

Statkraft etc; wind farm developers

HYWIND


Power control

“Pitch” versus “stall” and speed control

Power is a function of torque and speed: P = T · w

Turbine speed is determined by grid frequency, gear ratio and slip of

induction generator.

”STALL”: Passive torque regulation, determined by the turbine’s

aerodynamic properties.

”PITCH”: Active torque control through pitching of rotor blades

(applied for both optimization and power output limitation)

Gear-

box

PW vw

Pel

w Nett

fn

b

AG


Effektregulering

”Stall” og ”Pitch”

Turtall gitt av nettfrekvens, giromsetning og sakking i

asynkrongenerator.

”STALL”: Passiv effektregulering, gitt av turbinens aerodynamiske

karakteristikk.

”PITCH”: Aktiv effektstyring gjennom regulering av bladvinkel.

Benyttes for optimalisering og effektbegrensning

Gear-

box

PW vw

Pel

w Nett

fn

b

AG


Regulering av mekanisk moment Pitch/Stall

Source: Lubosny

www.windpower.org


Power control

“Pitch” versus “stall” and speed control

Source: Lubosny

www.windpower.org


Power versus windspeed curves

0

20

40

60

80

100

120

0 5 10 15 20 25 30

Wind speed (m/s)

Po

we

r (%

)

Pitch regulated

Stall regulated


Conventional pitch control

-15

-10

-5

0

5

10

15

20

25

0 5 10 15 20 25

Windspeed [m/s]

Pit

ch

an

gle

[d

eg

ree

s]

3000 kW

2500 kW

2000 kW

1500 kW

1000 kW

500 kW

0 kW

Power limitationOptimisation


Active stall control

-15

-10

-5

0

5

10

15

20

25

0 5 10 15 20 25

Windspeed [m/s]

Pit

ch

an

gle

[d

eg

ree

s]

3000 kW

2500 kW

2000 kW

1500 kW

1000 kW

500 kW

0 kW

Power limitationOptimisation

Documents

Vindkraft i kraftsystemet