Secure your environment with UiPath and CyberArk technologies - Session 1
Wind turbine power curves types & factors for evaluation
1. Machine Specific Site Specific Energy
distribution ,
kWh
Comments
Nacelle measured Nacelle Corrected
Machine (Standard)
Power Curve
Mast Power
Curve
Wind Speed
Frequency
Electric power &
Wind speed are
measured using
Nacelle top
reference.
Obtained after site
corrections
Machine: Manufacturer provides the long
term electric power values for the system.
Mast: Obtained from the long term mast
measurements of site characteristics.
Required for
evaluating power
curve & energy
distribution
It a measure of
site potential
with respect to
the machine
capacity.
Sensors quality is
major factor in
measurements
10 min time stamps
are used as
referenced by IEC
10 min time stamps
are used as
referenced by IEC
No specific criteria is used, however, data
is often used for interpolation purpose.
10 min time stamps
are used as
referenced by IEC
Varies with the
data quantity,
averaging
period.
IEC & National
standards referenced
are subjective.
Anemometer is on
nacelle top
---
Anemometers are installed on the met
masts.
Anemometer
rotation is converted
to wind speed signal.
Proportional to
wind speed
frequency.
It measures the wind
speed magnitude in
a place or site.
Measured data can
be correlated with
Mast
Analytical corrections
are applied on
measured data.
Corrections are “case & site specific”
Corrections are site
specific.
Corrections vary
with wind speed
frequency
Measure-Correlate-
Predict technique is
often used on data.
WIND POWER PLANT - POWER CURVES - TYPES, SCHEMATIC & COMMENTS
Nacelle measured
values
Nacelle corrected
values
Standard values
(Manufacturer)
Mast measured
OR Interpolated
Site wind speed frequency &
machine hours distribution
Energy
distribution, kWh
Corrections
• Air density
(temperature)
• Turbulence intensity.
• Wind speed1.
• Wind shear2
Compared
Compared
After
Correction/s
Before
Correction/s
Compared
Compared Site wind speed
frequency
Machine hours
Electric power multiplied with
Electric power multiplied with
Electric power multiplied with
Standard
(Manufacturer)
Nacelle
measured
Nacelle corrected
Mast measured
OR Interpolated
1
Converted
NOTE
1. Based upon measurement location
2. Based upon the height at a location.
2. 7/12/2014 2
Block #
Parameter
A B C D
BLOCK
RELATION
ENERGY
DISTRIBUTION
– WIND SPEED
BIN WISE
1
2
3
4
.
.
25
Nacelle
measured
Nacelle
corrected
Standard
(Manufacturer)
Mast
1 Electric power Electric power Electric power ---- A1 multiplied
with A3
2 Wind speed
frequency before
correction
Wind speed
frequency after
correction
-----
Wind speed
frequency
B1 multiplied
with B3
3 Machine hours
(Production)
Machine hours
(Production)
Machine hours
(Production)
---- C1 multiplied
with C3
𝐸1 + 𝐸2 + 𝐸3 + ⋯ 𝐸25
25
1
TOTAL ENERGY
WIND TURBINE POWER CURVE – TYPES – TABULAR FORM
BIN WISE SUMMATION OF ENERGY
3. 7/12/2014
3
POWER CURVE CORRECTIONS
WIND SPEED AIR DENSITY TURBULENCE INENSITY
Via Aerodynamic
Power Comparison
In Front of
turbine rotor,
after correction
Rotor
Behind the
turbine rotor
(anemometer
location)
TURBINE SYSTEM & ANEMOMETER
ANALYTICAL EMPIRICAL
WIND SHEAR
𝑃𝑓𝑟𝑜𝑛𝑡
Rotor diameter
at Anemometer
Wind speed after
correction
𝑃𝑒𝑙
η 𝑔𝑒𝑎𝑟𝑏𝑜𝑥 ∗ η 𝑔𝑒𝑛𝑒𝑟𝑎𝑡𝑜𝑟
+ 0.5 ∗ 𝜌 ∗
𝜋 ∗ 𝐷 𝑏𝑒𝑖𝑛𝑑
2
4
∗ 𝑣 𝑎𝑛𝑒𝑚𝑜𝑚𝑒𝑡𝑒𝑟
3
0.5 ∗ 𝜌 ∗
𝜋 ∗ 𝐷2
4
1
3
𝑃𝑟𝑜𝑡𝑜𝑟
𝑃𝑏𝑒𝑖𝑛𝑑
𝐷 𝑏𝑒𝑖𝑛𝑑 =
𝑃𝑓𝑟𝑜𝑛𝑡 = 𝑃𝑟𝑜𝑡𝑜𝑟 + 𝑃𝑏𝑒𝑖𝑛𝑑
𝑣 𝑎𝑓𝑡𝑒𝑟/𝑣 𝑏𝑒𝑓𝑜𝑟𝑒 = ℎ1
ℎ2
α
𝑣 𝑏𝑒𝑓𝑜𝑟𝑒 ∗
ℎ1
ℎ2
α
𝑣 𝑎𝑓𝑡𝑒𝑟 =
is the shear(power law) exponent
determined by the boundary
layer characteristics of the site
α
Wind speed after correction
Wind speed before correction
𝑃𝑐𝑜𝑟𝑟𝑒𝑐𝑡𝑒𝑑 = 𝑃𝑎𝑐𝑡𝑢𝑎𝑙 ∗ (
ρ 𝑐𝑜𝑟𝑟𝑒𝑐𝑡𝑒𝑑
ρ 𝑎𝑐𝑡𝑢𝑎𝑙
)
Pitch regulated
Stall regulated
𝐷 ± 𝑘𝑋
k – Wake decay constant for site
X – Anemometer distance behind the rotor
𝐼𝑣 = σ 𝑣 /𝑣 𝑎𝑣𝑔
𝐼 𝑏𝑒𝑓𝑜𝑟𝑒 = 𝜍 𝑣 𝑏𝑒𝑓𝑜𝑟𝑒
/𝑣 𝑏𝑒𝑓𝑜𝑟𝑒
𝐼𝑐𝑜𝑟𝑟𝑒𝑐𝑡𝑒𝑑 = σ 𝑣 𝑎𝑓𝑡𝑒𝑟
/𝑣 𝑎𝑓𝑡𝑒𝑟
𝑰 𝒄𝒐𝒓𝒓𝒆𝒄𝒕𝒆𝒅 =
𝝈 𝒗 𝒂𝒇𝒕𝒆𝒓
𝒗 𝒃𝒆𝒇𝒐𝒓𝒆
∗
𝒉 𝟐
𝒉 𝟏
𝜶
σ 𝑣 =
𝐼15 15+𝑎∗𝑣 𝑎𝑣𝑔
𝑎+1
Slope parameter of site
Standard deviation of
horizontal1wind speed
at hub height
Turbulence intensity
at 15 m/s
IEC Ed 2 & GL standard
definition for standard
deviation
Wind speed at hub height,𝑣 𝑏𝑒𝑓𝑜𝑟𝑒, 𝑣 𝑎𝑣𝑔
Wind speed after correction𝑣 𝑎𝑓𝑡𝑒𝑟
𝑃𝑐𝑜𝑟𝑟𝑒𝑐𝑡𝑒𝑑 = 𝑃𝑎𝑐𝑡𝑢𝑎𝑙 ∗
ρ 𝑐𝑜𝑟𝑟𝑒𝑐𝑡𝑒𝑑
ρ 𝑎𝑐𝑡𝑢𝑎𝑙
1
3
Note
1. Refers to longitudinal component