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7/23/2019 Control of Wind Power Plants
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1
Control of wind power plants
Poul Sørensen, Professor
Anca D. Hansen, Senior Researcher
Braulio Barahona, (former) Post Doc
DTU Wind Energy, Technical University of Denmark
DTU – Excellence since 1829
MISSIONDTU will develop and create valueusing the natural sciences and the
technical sciences to benefit society
2015-08-06
7/23/2019 Control of Wind Power Plants
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2
DTU Wind Energy, Technical University of Denmark
DTU organization
2015-08-06
DTU Wind Energy, Technical University of Denmark
DTU Wind Technology Expertise
2015-08-06
Wind Energy Division
Materials Research Division
Composites and Materials Mechanics
Materials Science and Characterisation
Fluid Mechanics
Test and Measurements
Wind Turbines Structures
Aerolastic Design
Meteorology
Wind Energy Systems
Fluid Dynamics
Composite Mechanics
7/23/2019 Control of Wind Power Plants
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3
DTU Wind Energy, Technical University of Denmark
Control issues
• List purposes of controlling wind power plants:
2015-08-06
DTU Wind Energy, Technical University of Denmark
4 wind turbine types
2015-08-06
GBASG
QC
ASG: Asynchronous generatorGB: GearboxQC: Reactive power compensationTR: TransformerVRR: Variable rotor resistance
TR
Type 1
GBASG
QC
TR
Type 2
VRR
GBASG
TR
Type 3
=
~
~
=
CHCL
CRGSC LSC
GSC: Generator side converterLSC: Line side converterCR: CrowbarC: DC link capacitorCH: ChopperL: Series inductanceSG: Synchronous generator
SG/ASG
GB
TR
Type 4
=
~
~
=
CHCL
GSC LSC
7/23/2019 Control of Wind Power Plants
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4
DTU Wind Energy, Technical University of Denmark
Outline
• General about wind turbine control
– blade angle control
– rotor speed control
• Electrical design and controllability / control strategies
– fixed speed
– variable speed
• Control examples
– Normal wind turbine operation control
• Fixed speed example (Active stall control)
• Variable speed example (doubly-fed and pitch control)
– Fault ride through wind turbine control• Active stall
• Doubly fed
– Wind turbine load reducing control
– Wind farm control
2015-08-06
DTU Wind Energy, Technical University of Denmark
Aerodynamic power – power curve
2015-08-06
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 5 10 15 20 25
Wind speed [m/s]
P o w e r ( p . u
. )
• P : aerodynamic power [W]
• U : wind speed
Power curve basedon 10 min averages
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5
DTU Wind Energy, Technical University of Denmark
Aerodynamic power – power coefficient
• P : aerodynamic power [W]
• : air density [kg/m3]
• A : rotor (swept) area
• U : wind speed
• C p : power coefficient
• : blade pitch angle
• : tip speed ratio
2015-08-06
,2
1 3
pC AU P
U
R
U
v
tip
A
vtip
U
Front view Side view
U
vtip
Top view
DTU Wind Energy, Technical University of Denmark
Aerodynamic power – power coefficient
2015-08-06
• P : aerodynamic power [W]
• U : wind speed
• : air density [kg/m3]
• A : rotor (swept) area
• : blade pitch angle
• : tip speed ratio
• C p : power coefficient
,2
1 3
pC AU P
-90
-45
0
45
90
5
10
15
20
0.0
0.1
0.2
0.3
0.4
0.5
Cp
P i t c h a n g l e [ d e g ]
T i p s p e
e d r a t i o
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6
DTU Wind Energy, Technical University of Denmark
Passive stall control
2015-08-06
W : relative speed seen from rotating blade
: angle of attack
L: lift
Power curve sensitive to• electrical grid frequency (3rd order)
• air density (1st order)
• dirt on blades
U
vtip = r
L
W
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 5 10 15 20 25
Wind speed (m/s)
P o w
e r ( p . u . )
50 Hz
48 Hz
51 Hz
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
-5 0 5 10 15 20
Angl e of at tack [de g]
L i f t c o e f f i c i e n t
DTU Wind Energy, Technical University of Denmark
Pitch control
2015-08-06
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 5 10 15 20 25
Wind speed [m/s]
P
o w
e r
( p .
u .
)
U
L
W
positive pitch
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
-5 0 5 10 15 20
Angl e of at tack [de g]
L i f t c o e f f i c i e n t
vtip = r
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7
DTU Wind Energy, Technical University of Denmark
Aktiv stall control (or kombi-stall)
2015-08-06
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 5 10 15 20 25
Wind speed [m/s]
P
o w
e r
( p .
u .
)
U
L
W
negative pitch
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
-5 0 5 10 15 20
Angl e of at tack [de g]
L i f t c o e f f i c i e n t
vtip = r
DTU Wind Energy, Technical University of Denmark
Fixed speed – active stall or pitch control
• Active (Combi) stall
• Moderate instantaneous responsegradients (fixed speed no problem)
• Slow blade angle control sufficient
• Pitch control
• Large instantaneous response gradientsfor power limitation (variable speeddesirable)
• Fast blade angle control necessary
2015-08-06
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
2.00
0 5 10 15 20 25
Wind speed [m/s]
P o w e r [ p u ] Pitch = 0 deg
Pitch = 5 deg
Pitch = 10 deg
Pitch = 15 deg
Pitch = 20 deg
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
2.00
0 5 10 15 20 25
Wind speed [m/s]
P o w e r [ p u ] Pitch = 0 deg
Pitch = -3 deg
Pitch = -6 deg
Pitch = -9 deg
Pitch = -12 deg
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8
DTU Wind Energy, Technical University of Denmark
Fixed speed – directly connected induction
generator
• WTR : wind turbine rotor speed
• gen : generator speed
• g : gear ratio
• 0 : electric grid radial speed (2 50 inEurope, 2 60 in USA)
• N pp : number of generator pole pairs
(typically 2 or 3)
• s << 1 : generator speed almost
“constant”
2015-08-06
Gear
box Induction
generator
0
pp
gen
1
N
sContactor
Main panel
bus bar
WTR
gen 0~
WTR gen g
DTU Wind Energy, Technical University of Denmark
Fixed speed – directly connected inductiongenerator
gen
2015-08-06
0 5 10 15 20 Time [ms]
0
N pp = 1
0
pp
gen
1
N
s
WTR gen g
• WTR : wind turbine rotor speed
• gen : generator speed
• g : gear ratio
• 0 : electric grid radial speed (2 50 inEurope, 2 60 in USA)
• N pp : number of generator pole pairs
(typically 2 or 3)
• s : slip. s << 1 : generator speed almost
“constant”
gen
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9
DTU Wind Energy, Technical University of Denmark
• WTR : wind turbine rotor speed
• gen : generator speed
• g : gear ratio
• 0 : electric grid radial speed (2 50 inEurope, 2 60 in USA)
• N pp : number of generator pole pairs
(typically 2 or 3)
• s : slip. s << 1 : generator speed almost
“constant”
Fixed speed – directly connected induction
generator
2015-08-06
0 5 10 15 20 Time [ms]
N pp = 2
0
pp
gen
1
N
s
WTR gen g
gen
20
DTU Wind Energy, Technical University of Denmark
Fixed speed – directly connected inductiongenerator
2015-08-060
Gear
box Induction
generator
Contactor
Main panel bus bar
WTR
gen 0~
0.5Slip
• WTR : generator speed
• gen : generator speed
• g : gear ratio
• 0 : electric grid radial speed (2 50 inEurope, 2 60 in USA)
• N pp : number of generator pole pairs
(typically 2 or 3)
• s : slip. s << 1 : generator speed almost
“constant”
WTR gen g
0
pp
gen
1
N
s
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10
DTU Wind Energy, Technical University of Denmark
Fixed speed continuous operation - summary
• Wind turbines with directly connected induction generators are speedcontrolled by the generator torque, which is approximately proportionalto the slip (slip is difference between grid synchronous rotor speed andactual generator rotor speed).
• The generator can be “geared” by increasing the number of pole pairs
• Fixed speed turbines can control the speed by changing the number ofpole pairs, typically between 2 and 3, depending on the wind speed.
2015-08-06
DTU Wind Energy, Technical University of Denmark
Exercise 1: fixed speed
• Open excel sheet with C p data
• A fixed speed wind turbine with the C p data in table has rotor diameter 40m, tip speed 70 m/s. The air density i = 1.25 kg/m2. Make the power
curve if the pitch angle is 0 deg.
• At which pitch angle (integer degree) should the blades be mounted tothe hub to obtain the maximum power 600 kW? Hint: try to increase the
pitch angle negatively step by step and observe the power curve untilyou get the desired maximum.
• The turbine uses N pp=2 coupling of generator windings for high windspeeds and N pp=3 for low wind speeds. What is the tip speed for low wind
speeds?
• The turbine is passive stall controlled. Show the power curve for low windspeeds and high wind speeds, and identify the wind speed at whichswitching between generator speeds is feasible.
2015-08-06
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11
DTU Wind Energy, Technical University of Denmark
Active Stall example
2015-08-06
• General operation modes active stall
– Power optimisation (lookup table)
– Power limitation (closed loop powercontrol)
• Normal operation (averagedpower, sample & hold)
• Overpower protection(instant. power, continuouspitching )
– Transition between optimisationand limitation
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 5 10 15 20 25
Wind speed [m/s]
P o w
e r ( p .
u .
)
DTU Wind Energy, Technical University of Denmark
‐6
‐4
‐2
0
2
0 5 10 15 20 25
P i t c h a n g l e [ d e g ]
Wind
speed
[m/s]
0.0
0.1
0.2
0.3
0.4
0.5
‐10 ‐5 0 5 10
C p
Pitch
angle
[deg]
4 m/s
Power Optimisation
2015-08-06
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12
DTU Wind Energy, Technical University of Denmark
Power Optimisation
2015-08-06
0.0
0.1
0.2
0.3
0.4
0.5
‐10 ‐5 0 5 10
C p
Pitch
angle
[deg]
4 m/s
5 m/s
6 m/s
7 m/s
8 m/s
9 m/s
10 m/s
11 m/s
12 m/s
13 m/s
‐6
‐4
‐2
0
2
0 5 10 15 20 25
P i t c h a n g l e [ d e g ]
Wind speed [m/s]
DTU Wind Energy, Technical University of Denmark
Power Limitation
2015-08-06
0.0
0.5
1.0
1.5
2.0
2.5
3.0
‐10
‐8
‐6
‐4
‐2 0
P o w e r [ M W ]
Pitch angle [deg]
13 m/s
‐6
‐4
‐2
0
2
0 5 10 15 20 25
P i t c h a n g l e [ d e g ]
Wind speed [m/s]
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13
DTU Wind Energy, Technical University of Denmark
Power Limitation
2015-08-06
0.0
0.5
1.0
1.5
2.0
2.5
3.0
‐10 ‐8 ‐6 ‐4 ‐2 0
P o w e r [ M W ]
Pitch angle [deg]
13 m/s
14 m/s
15 m/s
16 m/s
17 m/s
18 m/s
19 m/s
20 m/s
21 m/s
22 m/s
23 m/s
24 m/s
‐6
‐4
‐2
0
2
0 5 10 15 20 25
P i t c h a n g l e [ d e g ]
Wind speed [m/s]
DTU Wind Energy, Technical University of Denmark
Transision
2015-08-06
‐6
‐4
‐
2
0
2
0 5 10 15 20 25
P i t c h a n g l e [ d e g ]
Wind speed [m/s]
Optimisation
Limitation
‐6
‐4
‐2
0
2
0 5 10 15 20 25
P i t c h a n g l e [ d e g ]
Wind speed [m/s]
Optimisation
Limitation
Transition
‐6
‐4
‐2
0
2
0 5 10 15 20 25
P i t c h a n g
l e [ d e g ]
Wind speed [m/s]
Optimisation
Limitation
Transition
Soft strategy
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14
DTU Wind Energy, Technical University of Denmark
Control Circuit
2015-08-06
Actual
Power
Power
Setpoint
Lookup
S&H
anti windup
mode selection:- up: power limitation- down: power optimisation
DTU Wind Energy, Technical University of Denmark
Simulation Power Optimisation
2015-08-06
250.0200.0150.0100.0050.000.00 [s]
8.667
8.296
7.924
7.553
7.181
6.810
Windfilter_moving_average_Common Model: o1
Windfilter_moving_average_Common Model: yo
wind speed8.1 m/s
250.0200.0150.0100.0050.000.00 [s]
900.9
812.5
724.0
635.5
547.1
458.6
Power_in_kW_Common Model: power
Powerfilter_moving_average_Common Model: yo
el. power 758.5 kW
250.0200.0150.0100.0050.000.00 [s]
0.50
0.39
0.27
0.16
0.04
-0.070
pitch_control_I_Common Model: w2
pitch_control_I_Common Model: limit
pitch angle0.193 deg
power optimisation 0.000
D I g S I L E N T
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15
DTU Wind Energy, Technical University of Denmark
Simulation Transition
2015-08-06
250.0200.0150.0100.0050.000.00 [s]
13.53
12.83
12.13
11.43
10.73
10.04
Windfilter_moving_average_Common Model: o1
Windfilter_moving_average_Common Model: yo
wind speed12.177 m/s
250.0200.0150.0100.0050.000.00 [s]
2381.
2189.
1998.
1806.
1615.
1424.
Power_in_kW_Common Model: power
Powerfilter_moving_average_Common Model: yo
el. power 2117.9 kW
250.0200.0150.0100.0050.000.00 [s]
1.236
0.20
-0.839
-1.876
-2.913
-3.951
pitch_control_I_Common Model: w2
pitch_control_I_Common Model: limit
power optimisation
0.000
pitch angle-2.301 deg
D I g S I L E N T
DTU Wind Energy, Technical University of Denmark
Simulation Power Limitation
2015-08-06
250.0200.0150.0100.0050.000.00 [s]
26.11
24.72
23.32
21.92
20.52
19.12
Windfilter_moving_average_Common Model: o1
Windfilter_moving_average_Common Model: yo
wind speed23.5 m/s
250.0200.0150.0100.0050.000.00 [s]
2180.
2113.
2045.
1977.
1910.
1842.
Power_in_kW_Common Model: power
Powerfilter_moving_average_Common Model: yo
el. power 2042.0 kW
250.0200.0150.0100.0050.000.00 [s]
1.288
0.02
-1.250
-2.519
-3.788
-5.057
pitch_control_I_Common Model: w2
pitch_control_I_Common Model: limit
pitch angle-4.768 deg
power limitation 1.000
D I g S I L E N T
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16
DTU Wind Energy, Technical University of Denmark
Simulation Overpower
2015-08-06
250.0200.0150.0100.0050.000.00 [s]
18.42
16.52
14.62
12.72
10.81
8.914
Windfilter_moving_average_Common Model: o1
Windfilter_moving_average_Common Model: yo
wind speed10.89 m/s
wind speed16.5 m/s
250.0200.0150.0100.0050.000.00 [s]
2908.
2546.
2184.
1821.
1459.
1097.
Power_in_kW_Common Model: power
Powerfilter_moving_average_Common Model: yo
el. power 2001.2 kW
el. power 2804.9 kW
250.0200.0150.0100.0050.000.00 [s]
1.336
-0.143
-1.622
-3.101
-4.580
-6.059
pitch_control_I_Common Model: w2
pitch_control_I_Common Model: limit
power optimisation 0.000
power limitation 1.000
pitch angle-2.5 deg
D I g S I L E N T
DTU Wind Energy, Technical University of Denmark
Overpower Protection
• Function of overpower protection
– Disable sample and hold
• (continuous controller action possible)
– Instantaneous power signal for power controller
• (controller uses instantaneous power instead of averagedpower)
– Overpower protection active for fixed period of time
2015-08-06
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18
DTU Wind Energy, Technical University of Denmark
Exercise 2 – variable speed
• The Cp data is used for a variable speed / pitch controlled wind turbinewith rotor diameter 80 m. Specify equation for power curve inoptimisation region A-B
• Specify the corresponding relation between wind turbine rotor speed andpower
• The generator is a doubly fed induction generator with two pole pairs( N pp=2). The generator speed at rated wind speed is 1650 rpm (i.e. the
maximum generator speed). The rated grid frequency is 50 Hz. Find thegenerator slip corresponding to rated wind speed.
• The rated rotor tip speed (rotor speed at rated wind speed) is 70 m/s.Find the gear ratio.
• Specify the relation between generator speed and power in region A-B
• Specify the relation between generator speed and torque in region A-B
2015-08-06
DTU Wind Energy, Technical University of Denmark
Variable speed control loops
2015-08-06
+
-
PI
ref
grid P
meas
gen
meas
grid P ref
convP
Pel
P- curve
+
-
meas
gen
rated
gen
PI Pitch
actuator
c
Speed loop
Power loop
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19
DTU Wind Energy, Technical University of Denmark
Doubly fed generator (DFG)
2015-08-06
DFIG control
Speed control loop Power control loop
Wind turbine control
Rotor side
converter control
Network side
converter control
Measurement
grid point M
AC
DC AC
DC
I rotor
gen
PWM PWM
N
T
ref
grid P
ref
grid Q
meas
dcU
meas
grid P
meas
grid P
meas
grid Q
meas
ac I
ref
dcU
rated ref
grid P ,
DTU Wind Energy, Technical University of Denmark
Doubly fed generator – power flow vs. rotorspeed
2015-08-06
0stator P
Sub-synchronous Over-synchronous
0stator P
S t a t o r c i r c u i t
0rotor P
Sub-synchronous Over-synchronous
0rotor P
Ro t o r c i r c u i t
rotor stator grid PPP mecP
Partial scale power converter
WRIG Grid
AC
DC AC
DC
Rotor side
converter Grid side
converter
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20
DTU Wind Energy, Technical University of Denmark
Simulation – optimal power control (AB)
2015-08-06
360.00287.98215.96143.9471.919-0.1000 ..
0.200
0.150
0.100
0.050
0.000
-0.0500
G: Protor [MW]
360.00287.98215.96143.9471.919-0.1000 ..
1.2673
1.1064
0.945
0.784
0.624
0.463
G: Pstator[MW]
Gen_PQ_controller: Pgrid [MW]
360.00287.98215.96143.9471.919-0.1000 ..
9.2525
8.7577
8.2629
7.7682
7.2734
6.7787
Tower shadow model: Wind [m/s]
D I g S I L E N T
Below synchronous
(variable reference speed)
Below synchronous
(variable reference speed) Above synchronous
(fixed reference speed)
DTU Wind Energy, Technical University of Denmark
Simulation – optimal power control (AB)
2015-08-06
360.00288.00216.00144.0072.0000.000 ..
1.1813
1.1352
1.0890
1.0429
0.997
0.951
G: Speed
360.00288.00216.00144.0072.0000.000 ..
750804.
624643.
498482.
372322.
246161.
120000.
Transmission model: Aerodynamic rotor [Nm]
360.00288.00216.00144.0072.0000.000 ..
0.555
0.493
0.431
0.370
0.308
0.246
G: Electrical Torque in p.u.
360.00288.00216.00144.0072.0000.000 ..
1.0000
0.600
0.200
-0.2000
-0.6000
-1.0000
Limited_power_controller model: Pitch
D I g S I L E N T
Below synchronous
(variable reference speed)
Below synchronous
(variable reference speed) Above synchronous
(fixed reference speed)
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21
DTU Wind Energy, Technical University of Denmark
Simulation - wind 7m/s – optimisation
strategy
2015-08-06
600.00479.98359.96239.94119.92-0.1000 ..
0.685
0.612
0.539
0.466
0.393
0.321
Gen_PQ_controller: P1
600.00480.00360.00240.00120.000.000 ..
8.3761
7.7706
7.1650
6.5594
5.9539
5.3483
Rotor wind model: wsfic
600.00480.00360.00240.00120.000.000 ..
1611.9
1540.1
1468.4
1396.7
1324.9
1253.2
Speed controller model: rotation_real
Speed controller model: rotation_ref
600.00480.00360.00240.00120.000.000 ..
0.420
0.206
-0.0075
-0.2213
-0.4352
-0.6490
Speed controller model: error
D I g S I L E N T
Power grid
Wind
Gen. Speed and Gen. ref. speed
Error
DTU Wind Energy, Technical University of Denmark
Simulation - wind 15 m/s
2015-08-06
600.00479.98359.96239.94119.92-0.1000 ..
2.0485
2.0318
2.0150
1.9982
1.9814
1.9647
Gen_PQ_controller: P1
600.00480.00360.00240.00120.000.000 ..
18.443
16.977
15.511
14.045
12.578
11.112
Rotor wind model: wsfic
600.00480.00360.00240.00120.000.000 ..
1712.2
1700.5
1688.9
1677.3
1665.6
1654.0
Speed controller model: rotation_real
Speed controller model: rotation_ref
600.00480.00360.00240.00120.000.000 ..
17.265
13.787
10.310
6.8323
3.3548
-0.1227
Power controller model: pitch
D I g S I L E N T
Power grid
Gen. Speed and gen. ref. speed
Pitch
Wind
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22
DTU Wind Energy, Technical University of Denmark
Simulation - wind 22 m/s
2015-08-06
600.00479.98359.96239.94119.92-0.1000 ..
2.4742
2.3253
2.1765
2.0276
1.8787
1.7299
Gen_PQ_controller: P1
600.00480.00360.00240.00120.000.000 ..
27.182
24.936
22.691
20.445
18.200
15.954
Rotor wind model: wsfic
600.00480.00360.00240.00120.000.000 ..
1856.4
1780.0
1703.6
1627.2
1550.8
1474.4
Speed controller model: rotation_real
Speed controller model: rotation_ref
600.00480.00360.00240.00120.000.000 ..
25.835
22.162
18.489
14.816
11.143
7.4701
Power controller model: pitch
D I g S I
L E N T
DTU Wind Energy, Technical University of Denmark
Gain scheduling
2015-08-06
0 5 10 15 20 25 30-0.5
-0.45
-0.4
-0.35
-0.3
-0.25
-0.2
-0.15
-0.1
-0.05
0
d
dP
ba y
0 5 10 15 20 25 30
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1
d
dP
ba y z
11
1
d
dPK K pitchPI
d
dPK K PI system
pitchPI K K
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23
DTU Wind Energy, Technical University of Denmark
Simulation - wind 22 m/s – gain schedulling
2015-08-06
600.00479.98359.96239.94119.92-0.1000 ..
2.4742
2.3254
2.1765
2.0277
1.8788
1.7300
Gen_PQ_controller: P1
600.00479.98359.96239.94119.92-0.1000 ..
27.182
24.935
22.688
20.441
18.194
15.947
Rotor wind model: wsfic
600.00479.98359.96239.94119.92-0.1000 ..
1767.2
1730.8
1694.4
1657.9
1621.5
1585.0
Speed controller model: rotation_real
Speed controller model: rotation_ref
600.00479.98359.96239.94119.92-0.1000 ..
28.381
25.594
22.806
20.018
17.230
14.442
Power control schedulling model: pitch
D I g S I L E N T
Power grid
Gen. Speed and Gen. ref. speed
Pitch
DTU Wind Energy, Technical University of Denmark
Fault-ride-through control
• Example active stall
– short circuit at “Fault Bus”
– isolation of fault
2015-08-06
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24
DTU Wind Energy, Technical University of Denmark
No fault-ride-through control
2015-08-06
6.0004.8003.6002.4001.200-0.000 [s]
3.380
2.610
1.840
1.070
0.30
-0.470
WT Generator: Active Power in MW
6.0004.8003.6002.4001.200-0.000 [s]
1.030
0.85
0.68
0.50
0.33
0.15
WT Generator: Terminal Voltage in p.u.
6.0004.8003.6002.4001.200-0.000 [s]
1.100
1.078
1.056
1.034
1.012
0.99
WT Generator: Speed in p.u.
6.0004.8003.6002.4001.200-0.000 [s]
1.800
0.85
-0.095
-1.043
-1.990
-2.938
WT Generator: Reactive Power in MVAr
D I g S I L E N T
DTU Wind Energy, Technical University of Denmark
Simple fault-ride-thorugh control: fast pitchto zero-power
2015-08-06
-14
-12
-10
-8
-6
-4
-2
0
2
4
4 5 6 7 8 9 10 11 12 1 3 14 15 16 1 7 18 19 2 0 21 2 2 23 24 2 5
wind speed [m/s]
p i t c h
a n
g l e
[ d e g ]
normal operation pitch
0.0 MW pitch
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25
DTU Wind Energy, Technical University of Denmark
Short circuit simulated with fault-ride-
through control
2015-08-06
6.0004.8003.6002.4001.200-0.000 [s]
3.039
2.391
1.743
1.096
0.45
-0.200
WT Generator: Active Power in MW
6.0004.8003.6002.4001.200-0.000 [s]
1.098
0.91
0.72
0.53
0.34
0.15
WT Generator: Terminal Voltage in p.u.
6.0004.8003.6002.4001.200-0.000 [s]
1.077
1.058
1.038
1.019
1.00
0.98
WT Generator: Speed in p.u.
6.0004.8003.6002.4001.200-0.000 [s]
2.051
1.059
0.07
-0.926
-1.918
-2.910
WT Generator: Reactive Power in MVAr
D I g S I L E N T
DTU Wind Energy, Technical University of Denmark
Fault ride through – DFG with crowbar
2015-08-06
Crowbar
DFIG
~=
~~~
Power convertercontrol
ref Qref P
Control mode :• normal operation• fault operation
~=
RSC GSC
Faultdetection
Drive train
with gearbox
Wind turbine
Pitch anglecontrol
DFIG system – control and protection
Aerodynamics
k
c
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26
DTU Wind Energy, Technical University of Denmark
Crowbar effects
• On voltage dip:
– RSC overcurrents
– Crowbar activtates / RSCdisconnects
– DFG behaves as SCIG (nocontrol)
– GSC can still be used as aSTATCOM
• Effect of increased crowbarresistance :
– improves the torquecharacteristic
– reduces reactive powerdemand
– improves dynamic stability ofthe generator
2015-08-06
Damping controller
-1 -0.5 0 0.5 1 1.5 2 2.5 3-25
-20
-15
-10
-5
0
Speed [p.u.]
R e a c t i v e p o w e r [
M v a r ]
. . . .
-1 -0.5 0 0.5 1 1.5 2 2.5 3-3
-2
-1
0
1
2
3
Speed [p.u.]
E l e c t r o m a g n e t i c
t o r q u e
[ p . u . ]
crowbar crowbar crowbar R R R 321
crowbar crowbar crowbar R R R 321
DTU Wind Energy, Technical University of Denmark
Load reduction – active damping
2015-08-06
Wind
speed
ref
grid
ref P
-+
Damping controller
PIOptimal
speed
10.007.505.002.500.00 [s]
1.150
1.125
1.100
1.075
1.050
1.025
10.007.505.002.500.00 [s]
3.0E+4
2.0E+4
1.0E+4
0.0E+0
-1.0E+4
10.007.505.002.500.00 [s]
10.00
8.000
6.000
4.000
2.000
0.00
10.007.505.002.500.00 [s]
2.40
2.20
2.00
1.80
1.60
1.40
1.20
D I g S I L E N T
G e n e r a t o r s p e e d
[ p u
]
Withoutdampingcontroller Withdampingcontroller
M
e c h a n
i c a l t o r q u e
[ N m
]
[sec]
[sec]
[sec]
[sec]
P i t c h a n g
l e [ d e g
]
A e r o .
p o w e r
[ M W ]
10.007.505.002.500.00 [s]
1.150
1.125
1.100
1.075
1.050
1.025
10.007.505.002.500.00 [s]
3.0E+4
2.0E+4
1.0E+4
0.0E+0
-1.0E+4
10.007.505.002.500.00 [s]
10.00
8.000
6.000
4.000
2.000
0.00
10.007.505.002.500.00 [s]
2.40
2.20
2.00
1.80
1.60
1.40
1.20
D I g S I L E N T
G e n e r a t o r s p e e d
[ p u
]
Withoutdampingcontroller Withoutdampingcontroller Withdampingcontroller Withdampingcontroller
M
e c h a n
i c a l t o r q u e
[ N m
]
[sec]
[sec]
[sec]
[sec]
P i t c h a n g
l e [ d e g
]
A e r o .
p o w e r
[ M W ]
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27
DTU Wind Energy, Technical University of Denmark
Integrated design analysis
and load reduction
• Integrated analysis model
– Aeroelastic model of windturbine (HAWC2)
– Pitch control (Simulink)
– Asynchronous machine +control (Simulink)
• Rotor and Statorfluxes
• Current and powercontrol of rotorside converter
• Resonant dampingcontrol
2015-08-06
DTU Wind Energy, Technical University of Denmark
Resonant damping control – load reductionUnbalanced fault
2015-08-06
Electrical loads:Generator rotor current
Structural loads:Tower top side-to-side moment
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28
DTU Wind Energy, Technical University of Denmark
Resonant damping control – load reduction
2015-08-06
Load ranges(max – min)
Equivalent loads(fatigue)
DTU Wind Energy, Technical University of Denmark
Storm control
High Wind Shut Down High Wind Ride Through
(SIEMENS HWRT™)
2015-08-06
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29
DTU Wind Energy, Technical University of Denmark
Offshore wind power variability 2020
2015-08-06
DTU Wind Energy, Technical University of Denmark
Wind farm control – wind power plants
• Contribute to control of grid voltage: amplitude and frequency, like otherpower plants
• Indirect grid control: active and reactive power control
2015-08-06
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30
DTU Wind Energy, Technical University of Denmark
Balance control
• Balance control provides power output according to reference signal
• Balance control implemented in first time in Horns Rev 2002
• Why ramp limitation
2015-08-06
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 100 200 300 400 500 600
Time [s]
P o w e r [ p u . ]
PavailPbalPref,wf
DTU Wind Energy, Technical University of Denmark
Delta control
• Delta control provides fixedreserve
• Delta control implemented firsttime in Horns Rev 2002
• Reserve can be utilised infrequency control (droop anddeadband)
2015-08-06
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 100 200 300 400 500 600
Time [s]
P o w e r [ p u . ]
Pref,wf
Power
Frequency
Pavail
f s f s+ f d f d +
PdelPavailPdelPdel
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31
DTU Wind Energy, Technical University of Denmark
Double fed wind turbine – power control
2015-08-06
Wind turbine controller Wind turbine controller Wind turbine controller
Power
control
meas
Speed
control
pitch
gen
ref P
max ~~
ref P
DTU Wind Energy, Technical University of Denmark
Double fed wind farm – power control
2015-08-06
Wind turbine controller Wind turbine controller Wind farm controller Operator Wind turbine controller
Power
reference
setting
Pbalance
P
Ramp rate settings
Dispatch
controlPower
control
wf
ref P
wf
measP
meas
Speed
control
pitch
gen
ref P
~~
inst
availP
measP
ref P
max
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32
DTU Wind Energy, Technical University of Denmark
Double fed wind farm – power control
2015-08-06
Wind turbine controller Wind turbine controller Wind farm controller Operator Wind turbine controller
Power
reference
setting
Pbalance
P
Ramp rate settings
Dispatch
controlPower
control
wf
ref P
wf
measP
meas
Speed
control
pitch
gen
ref P
ref Speed
optimum
~~
measu
inst
availP
DTU Wind Energy, Technical University of Denmark
Double fed wind farm – power control
2015-08-06
Wind turbine controller Wind turbine controller Wind farm controller Operator Wind turbine controller
Power
reference
setting
Pbalance
P
Ramp rate settings
Dispatch
controlPower
control
wf
ref P
wf
measP
meas
Speed
control
pitch
gen
ref P
ref Speed
optimum
Wind
speeds
forecasts ~~
measu
inst
availP
t expu
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33
DTU Wind Energy, Technical University of Denmark
Double fed wind farm – frequency control
2015-08-06
Wind turbine controller Wind turbine controller Wind farm controller Operator Wind turbine controller
Power
reference
setting
Pbalance
P
Ramp rate settings
Droop settings
Deadband settings
Dispatch
controlPower
control
wf
ref P 0
meas f
wf
ref P
wf ref
P
wf
measP
meas
Speed
control
pitch
gen
ref P
ref
Speed
optimum
~~
measu
inst
availP
t expuWind
speeds
forecasts
DTU Wind Energy, Technical University of Denmark
Wind farm power control – wind turbines
2015-08-06
350.0280.0210.0140.070.000.00 [s]
21.00
18.00
15.00
12.00
9.00
6.00
350.0280.0210.0140.070.000.00 [s]
2.10
1.80
1.50
1.20
0.90
0.60
0.30
350.0280.0210.0140.070.000.00 [s]
1700.00
1600.00
1500.00
1400.00
1300.00
350.0280.0210.0140.070.000.00 [s]
20.00
16.00
12.00
8.00
4.00
-0.00
-4.00
D I g S I L E N T
Wind -WT1
Wind -WT2
Wind -WT3
Measured power -WT1
Measured power -WT2Measured power -WT3
Generator speed -WT1
Generator speed -WT2
Generator speed -WT3
Pitch angle -WT1
Pitch angle -WT2
Pitch angle -WT3
[ M W
]
[ m / s ]
[ r p m
]
[ d e g
]
[sec]
350.0280.0210.0140.070.000.00 [s]
21.00
18.00
15.00
12.00
9.00
6.00
350.0280.0210.0140.070.000.00 [s]
2.10
1.80
1.50
1.20
0.90
0.60
0.30
350.0280.0210.0140.070.000.00 [s]
1700.00
1600.00
1500.00
1400.00
1300.00
350.0280.0210.0140.070.000.00 [s]
20.00
16.00
12.00
8.00
4.00
-0.00
-4.00
D I g S I L E N T
Wind -WT1
Wind -WT2
Wind -WT3
Measured power -WT1
Measured power -WT2Measured power -WT3
Generator speed -WT1
Generator speed -WT2
Generator speed -WT3
Pitch angle -WT1
Pitch angle -WT2
Pitch angle -WT3
[ M W
]
[ m / s ]
[ r p m
]
[ d e g
]
[sec]
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DTU Wind Energy, Technical University of Denmark
Wind farm power control
2015-08-06350.0280.0210.0140.070.000.00 [s]
6.50
6.00
5.50
5.00
4.50
4.00
3.50
350.0280.0210.0140.070.000.00 [s]
2.20
2.00
1.80
1.60
1.40
1.20
1.00
350.0280.0210.0140.070.000.00 [s]
2.20
2.00
1.80
1.60
1.40
1.20
350.0280.0210.0140.070.000.00 [s]
2.40
2.00
1.60
1.20
0.80
0.40
D I g S I L E N T
Dispatch reference power -WT1
Dispatch reference power - WT2
Dispatch reference power -WT3
Available power -WT1
Available power -WT2
Available power -WT3
Wind farm available power Wind farm PCC measured power
[ M W ]
[ M W ]
[ M W ]
[ M W ]
[sec] 350.0280.0210.0140.070.000.00 [s]
6.50
6.00
5.50
5.00
4.50
4.00
3.50
350.0280.0210.0140.070.000.00 [s]
2.20
2.00
1.80
1.60
1.40
1.20
1.00
350.0280.0210.0140.070.000.00 [s]
2.20
2.00
1.80
1.60
1.40
1.20
350.0280.0210.0140.070.000.00 [s]
2.40
2.00
1.60
1.20
0.80
0.40
D I g S I L E N T
Dispatch reference power -WT1
Dispatch reference power - WT2
Dispatch reference power -WT3
Available power -WT1
Available power -WT2
Available power -WT3
Wind farm available power Wind farm PCC measured power
[ M W ]
[ M W ]
[ M W ]
[ M W ]
[sec]
DTU Wind Energy, Technical University of Denmark
Summary / conclusions
• Control can
– optimise production
– reduce structural loads
– support grid integration
• Controllability varies very much, depending on turbine design (fixed/varspeed, fixed/var pitch)
• QUESTIONS?
2015-08-06