ribeiro carla
DESCRIPTION
TRANSCRIPT
An investigation into turbine performance and wind flow modelling
under cold weather driven stable atmospheric conditions
Winterwind 2013 (Östersund, Sweden - 13 February 2013)
GL Garrad Hassan – Independent Renewable Experts
Almost 1000 staff, in 44 locations, across 26 countries
Vancouver
Ottawa
Portland
San Diego
Montreal
Peterborough
Austin
Querétaro
Porto Alegre
Santiago
Beijing
Seoul
Tokyo
Shanghai
Mumbai
Bangkok
Bangalore
Singapore
Newcastle
Wellington
Melbourne
BristolCork
Paris
Izmir
Cairo
CopenhagenHinnerupOldenburgHamburgWarsaw
Lisbon
BarcelonaZaragozaMadrid
Imola
London
Slough
Glasgow
Cape Town
HeerenveenSint Maarten
Kaiser-Wilhelm-Koog
Content
Cold climate driven stable atmospheric conditions in the Nordic Region:
1 - Consequences to the wind flow (challenges) and how it translates
2 - How complex CFD flow modelling can help with the wind flow modelling challenges
3 - Impact of high frequency of stable atmospheric conditions on turbine performance
1– 2 – 3
Stable atmospheric conditions
What is it and how it translates
Radiative cooling driven stable atmospheric conditions
- Unstable, neutral, stable and very stable atmospheric conditions
- High frequency of stable atmospheric conditions
- Actual
- Dry-adiabatic
Radiative cooling driven stable atmospheric conditions
- When do stable and very stable atmospheric conditions happen in the Nordic region
Radiative cooling driven stable atmospheric conditions
- When do stable and very stable atmospheric conditions happen in the Nordic region
Radiative cooling driven stable atmospheric conditions
- When do stable and very stable atmospheric conditions happen in the Nordic region
Radiative cooling driven stable atmospheric conditions
- When do stable and very stable atmospheric conditions happen in the Nordic region
Radiative cooling driven stable atmospheric conditions
- When do stable and very stable atmospheric conditions happen in the Nordic region
Radiative cooling driven stable atmospheric conditions
- When do stable and very stable atmospheric conditions happen in the Nordic region
Radiative cooling driven stable atmospheric conditions
- When do stable and very stable atmospheric conditions happen in the Nordic region
Radiative cooling driven stable atmospheric conditions
- When do stable and very stable atmospheric conditions happen in the Nordic region
Radiative cooling driven stable atmospheric conditions
- When do stable and very stable atmospheric conditions happen in the Nordic region
Radiative cooling driven stable atmospheric conditions
- When do stable and very stable atmospheric conditions happen in the Nordic region
High frequency of stable atmosphere and wind conditions
Low TI as a proxy for stable
atmospheric conditions
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
1.05
1.10
0 30 60 90 120 150 180 210 240 270 300 330
Speedup
Direction Sector (deg)
Stable Unstable Total
Wind Flow modelling challenges
Wind speed at mast A/Wind speed at mast B = Speedup
1–2 – 3
Complex CFD flow modelling for
stable wind flow challenges
• Most accurate description of wind flow: Navier-Stokes Equations (below)
• Very difficult to solve!
• Linear models simplify this equation - some accuracy is sacrificed
• CFD makes fewer changes – less loss of accuracy:
• Reynolds-Average Navier-Stokes (RANS)
• Advanced software required
• Modern computing power required
• Like a wind tunnel on your computer
What is CFD (Computational Fluid Dynamics)
Directional speedup errors (95 mast pairs at 16 sites)
Linear
(WAsP)
Neutral CFD
Wind Flow modelling under stable conditions
Average Errors
Linear (WAsP) = 9.6%
Neutral CFD = 9.5%
Stable + Neutral (CFD) = 6.6%
Stable+Neutral
error is lower
Stable + Neutral CFD approach (GL GH approach)
Directional speedup errors (95 mast pairs at 16 sites)
1– 2 –3High frequency of stable conditions
and turbine performance
Performance of wind turbines under stable conditions in the
Nordic Region – What the theory suggests
P = 1/2ρ(u)3(1+3TI2)ACp
0
500
1000
1500
2000
2 4 6 8 10 12 14
Po
wer
(KW
)
Wind speed (m/s)
0%
5%
10%
15%
20%
92%
94%
96%
98%
100%
102%
104%
106%
6 7 8
Low
TI
/ H
igh
TI
me
asu
red
po
we
r cu
rve
pro
du
ctio
n
Annual mean wind speed (m/s)
T1
T2
T3
T4
T5
Average
Performance of wind turbines under stable conditions in the
Nordic Region
Results for IEC Power Curve Measurements of 5 mast/turbine pairs in Sweden
No partial icing cleaning
and no temperature
filtering
92%
94%
96%
98%
100%
102%
104%
106%
6 7 8
Low
TI
/ H
igh
TI
me
asu
red
po
we
r cu
rve
pro
du
ctio
n
Annual mean wind speed (m/s)
T1
T2
T3
T4
T5
Average
Performance of wind turbines under stable conditions in the
Nordic Region
Results for IEC Power Curve Measurements of 5 mast/turbine pairs in Sweden
Data cleaned for partial
icing and filtered
excluding temperatures
below 0˚C
92%
94%
96%
98%
100%
102%
104%
106%
6 7 8
Low
TI
/ H
igh
TI
me
asu
red
po
we
r cu
rve
pro
du
ctio
n
Annual mean wind speed (m/s)
T1
T2
T3
T4
T5
Average
Performance of wind turbines under stable conditions in the
Nordic Region
Results for IEC Power Curve Measurements of 5 mast/turbine pairs in Sweden
Data cleaned for partial
icing and filtered
excluding temperatures
below 0˚C and different
site calibration speedups
applied for stable and
unstable conditions
Performance of wind turbines under stable conditions in the
Nordic Region
Results for IEC Power Curve Measurements of 5 mast/turbine pairs in Sweden
Without different site calibration speedups With different site calibration speedups
80%
85%
90%
95%
100%
105%
110%
4 5 6 7 8 9 10 11 12 13 14 15 16 17
Low
TI
/ H
igh
TI
me
asu
red
po
we
r cu
rve
Wind speed (m/s)
T1 T2 T3 T4 T5 Average
80%
85%
90%
95%
100%
105%
110%
4 5 6 7 8 9 10 11 12 13 14 15 16 17
Lo
w T
I / H
igh
TI
me
asu
red
po
we
r cu
rve
Wind speed (m/s)
T1 T2 T3 T4 T5 Average
Conclusions
� There is high frequency of stable and very stable atmospheric conditions in sites
across the Nordic Region caused by radiative cooling
� This presents a challenge for both wind flow modelling and turbine performance
� Stable CFD reduces the error in wind flow modelling at these sites
� Theory shows that low turbulence reduces turbine performance in raising part of
the power curve
� Preliminary Nordic data supports this, however shows recovery in the “knee” of
the power curve
� Need to gather more Power Curve Measurement data across the Nordic region
� Careful consideration should be given to winter Power Curve Measurement data,
as partial icing affects more low TI data than high TI, and the anemometry used
� Site calibration speedups for stable and unstable conditions should be considered
separately as suggested by the new draft of the IEC standard
Thank you
Contact:
Carla Ribeiro, Senior Team Leader Nordic Region
With Thanks to:
Simon Cox
Bob Hodgetts
Andrew Tindal
GL GH CFD Team
GL GH AMOS Team
Any questions?