analysis of a 1.7 mva doubly fed wind-power induction generator during power systems disturbances...
TRANSCRIPT
Analysis of a 1.7 MVA Doubly Fed Wind-Power Induction Generator during Power
Systems Disturbances
Slavomir Seman, Sami Kanerva, Antero Arkkio
Laboratory of Electromechanics
Helsinki University of Technology
Jouko Niiranen
ABB Oy, Finland
HELSINKI UNIVERSITY OF TECHNOLOGYDepartment of Electrical and Communications Engineering
Overview
• Introduction
• The Doubly Fed Induction Generator
• Frequency Converter and Control
• Crowbar
• Modeling of The Network, Transformer and Transmission
Line
• Simulation Results
• Conclusions
Rs RrLsl Lrl
Lmus
j(k
r
r
im
irisjk
s
ur
The Doubly Fed Induction Generator
P N 1.7 MW
U N, stator (L-L) 690 V (delta)
U max, rotor 2472 V (star)
n N 1500 rpm
f N, stator 50 Hz
Transient Model of the Generator
• The machine equations x-y reference frame fixed with rotor
• Constant speed - no equation of movement included
Frequency Converter and Control
Model of the Frequency Converter
• Two back-to-back connected voltage source inverters (VSI)
• DTC
• The Network Side Converter - simplification 1-st order filter transfer function
• PI controller Udc -level
The Rotor Side Converter
Model of the Rotor Side Converter
• Modified DTC
• Input demanded PF or Q , Tref
• Voltage vector applied - optimal switching table
• The tangential component of the voltage vector controls the torque whereas the radial component increases or decreases the flux magnitude
Over-Current Protection - Crowbar
ra ra rb rb rc rc( i -i + i -i + i -i )/2crowI
maxdc dcU U
_crow crow crow CB semicU R I U
Passive Crowbar
• over-current protection - the rotor, rotor side converter
• no chopper mode
• disconnection of the converter rotor is connected to CB
• CB is active until MCB disconnects stator from the network
Modeling of the Network, Transformer and Transmission Line
Modelling of test set-up
• Power supply - SG or 3-phase V source with short circuit reactance and inductance
• Transmission line - R-L equivalent circuit
• Transformer - short circuit R-L and stray C, no saturation
• Short circuiting TR - R-L equivalent circuit
Simulation Results - Voltage Dip without Crowbar
Matlab-Simulink, t_step = 0.5e-7, T_ref =0.5 p.u., w_ref = 1.067 p.u., Voltage dip 35% Un
4.8 4.9 5 5.1 5.2 5.3 5.4-1.5
-1
-0.5
0
0.5
1
1.5
t [s]
vas
var
ud
c [
p.u
.]
Stator voltage A - phaseRotor voltage A - phaseDC-link voltage
Voltage dip applied MCB open
Simulation Results - Voltage Dip without Crowbar
4.8 4.9 5 5.1 5.2 5.3 5.4-2
-1
0
1
2
3
4
t [s]
ias
iar
T e [p.u
.]
Stator current A - phaseRotor current A - phaseElectromagnetic torque
Voltage dip applied MCB open
Simulation Results - Voltage Dip with Passive Crowbar
4.8 4.9 5 5.1 5.2 5.3 5.4-1.5
-1
-0.5
0
0.5
1
1.5
t [s]
vas
var
ud
c [
p.u
.]
Stator voltage A - phaseRotor voltage A - phaseDC-link voltage
Voltage dip applied MCB open
Matlab-Simulink, t_step = 0.5e-7, T_ref =0.5 p.u., w_ref = 1.067 p.u., Voltage dip 35% Un
Simulation Results - Voltage Dip with Passive Crowbar
4.8 4.9 5 5.1 5.2 5.3 5.4-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
t [s]
ias
ia r T e [
p.u
.]
Stator current A - phaseRotor current A - phaseElectromagnetic torque
Voltage dip applied MCB open
• Transient behaviour of DTC controlled DFIG for wind-power
applications studied.
• The transient simulation results with and without crowbar were
compared.
• When the crowbar is implemented, the stator and rotor transient
current decay rapidly and rotor circuit is properly protected.
• Transient electromagnetic torque is reduced by means of crowbar but
oscillates longer than in case without crowbar.
Conclusions