dynamic response of grid connected wind turbine with dfig
TRANSCRIPT
Chalmers University of Technology
Dynamic Response of grid Connected Wind Turbine with
DFIG during Disturbances
Abram Perdana, Ola Carlson
Dept. of Electric Power Engineering
Chalmers University of Technology
Jonas Persson
Dept. of Electrical Engineering
Royal Institute of Technology
Chalmers University of Technology
1. Background & objectives
2. Model of WT with DFIG
3. Simulation
a. Fault and no protection action
b. Fault in super-synchronous operation + protection action
c. Fault in sub-synchronous operation + protection action
4. Effect of saturation
5. Conclusions
Contents of Presentation
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Objectives
Possibilities and constraints for designing fault ride through strategy safe for both WT and the grid
Presentation of DFIG’s behavior during grid disturbances in different cases
Background
DFIG accounts for 50% of market share
Tightened grid connection requirements immunity of DFIG to external faults is becoming an issue
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Inductiongenerator
model
Turbinemodel
Drive-trainmodel
The gridmodel
Pitchcontroller
model
Rotor-sideconverter
mT
teT
g geni
genu
ru
windv
infufault
signal
Model Structure
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r
refP
r
ms
seref
Lu
LT
erefTrefP
su
rqrefi
rdrefi
sQ
srefQsrefu
su
+- -
+
Reactive power controller
Active power controller
Rotor Side Converter Controller
sa
ssss j
dt
diru
rrar
rrr jdt
diru
0
0,5
1
1,5
0 1 2 3 4
Current (pu)
|)(| i
|)(| LiL
Wound rotor induction generator
Saturation
Generator Model
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max=90 min=0 max=90
min=0 rate limit 7 deg/sec
1 s
* t
* t
Pitch Controller
Turbine Model
tip-speed ratiopitch angle
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Turbine
Gearbox
Generator
Stiffness
Damping
gtstgstt
t DKTdt
dH
2
gtstgsgg
g DKTdt
dH
2
Drive-train Model
DFIG InfiniteBus
Fault100 ms
0.027+j0.164 pu
Pgen = 2 MW (1 pu)
0.027+j0.164 pu
RfaultVinf = 1 0o pu
Grid Model
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DFIG InfiniteBus
Fault100 ms
0.027+j0.164 pu
Pgen = 2 MW (1 pu)
0.027+j0.164 pu
RfaultVinf = 1 0o pu
Rfault = 0.05 pu
Avg. wind speed = 7.5 m/s
Case 1: Small disturbance, no protection action
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Case 1: Small disturbance, no protection action
active & reactive power
turbine & generator speed
rotor currentstator current
terminal voltage
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DFIG InfiniteBus
Fault100 ms
0.027+j0.164 pu
Pgen = 2 MW (1 pu)
0.027+j0.164 pu
RfaultVinf = 1 0o pu
Rfault = 0.01 pu
Avg. wind speed = 11 m/s
Case 2: Protection action during super-synchronous speed
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Case 2: Protection action during super-synchronous speed
Sequence:A. Fault occursB. If ir > 1.5 pu:
converter is blocked &rotor is short-circuited
C. Generator is disconnectedD. Fault is cleared
rotorcircuit
ir
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terminal voltage
active power reactive power
stator current
Case 2: Protection action during super-synchronous speed
Insertion of external rotor resistance
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Case 2: Protection action during super-synchronous speed
no disconnection
generator & turbine speed
disconnection + acting of pitch angle
generator & turbine speed
pitch angle
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DFIG InfiniteBus
Fault100 ms
0.027+j0.164 pu
Pgen = 2 MW (1 pu)
0.027+j0.164 pu
RfaultVinf = 1 0o pu
Rfault = 0.01 pu
Avg. wind speed = 9 m/s
Case 3: Protection action during sub-synchronous speed
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Case 3: Protection action during sub-synchronous speed
terminal voltage stator current
active power reactive power
turbine & generator speed
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Effect of Saturation in the Model
stator current rotor current
0
0,5
1
1,5
0 1 2 3 4
Current (pu)
|)(| i
|)(| LiL
saturation curve
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• DFIG provides a better terminal voltage recovery compared DFIG provides a better terminal voltage recovery compared to SCIG during (small) disturbance when no converter to SCIG during (small) disturbance when no converter blocking occurs, blocking occurs,
• for severe voltage dips DFIG will be disconnected from the for severe voltage dips DFIG will be disconnected from the grid (with conventional strategy)grid (with conventional strategy)– converter blocking during super-synchronous operation converter blocking during super-synchronous operation
causes causes high reactive powerhigh reactive power consumption, consumption,
– converter blocking during sub-synchronous operation causes converter blocking during sub-synchronous operation causes highhigh reactivereactive and and active poweractive power absorption and abrupt change absorption and abrupt change of rotor speedof rotor speed
• Saturation model predicts higher value of stator & rotor Saturation model predicts higher value of stator & rotor currents, therefore it is important to include in designing currents, therefore it is important to include in designing protectionprotection
Conclusions