Download Project meeting 3.6.2003

HELSINKI UNIVERSITY OF TECHNOLOGY
Department of Electrical and Communications Engineering
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
Overview
• Introduction
• The Doubly Fed Induction Generator
• Frequency Converter and Control
• Crowbar
• Modeling of The Network, Transformer and Transmission Line
• Simulation Results
• Conclusions
The Doubly Fed Induction Generator
is
Rs
jks
Lrl
Lsl
j(krr
Rr
Transient Model of the
Generator
ir
• The machine equations x-y
im
us
Lm
ur
reference frame fixed with
rotor
• Constant speed - no equation
of movement included
P
U
1.7 MW
N
N, stator
U
(L-L) 690 V (delta)
max, rotor
n
f
N
N, stator
2472 V (star)
1500 rpm
50 Hz
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
Passive Crowbar
• over-current
protection - the rotor,
rotor side converter
• no chopper mode
• disconnection of the
converter rotor is
connected to CB
U dc  U dc max
I crow  ( ira -ira + irb -irb + irc -irc )/2
• CB is active until MCB
disconnects stator from
the network
U crow  Rcrow I crow  U CB _ semic
Modeling of the Network, Transformer and
Transmission Line
Modelling of test set-up
• Power supply - SG or 3phase 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
1.5
Stator voltage A - phase
Rotor voltage A - phase
DC-link voltage
vas var udc [p.u.]
1
0.5
0
-0.5
-1
-1.5
4.8
4.9
5
5.1
5.2
5.3
t [s]
Voltage dip applied
MCB open
5.4
Simulation Results - Voltage Dip without Crowbar
4
Stator current A - phase
Rotor current A - phase
Electromagnetic torque
3
ias iar Te [p.u.]
2
1
0
-1
-2
4.8
4.9
5
5.1
5.2
5.3
t [s]
Voltage dip applied
MCB open
5.4
Simulation Results - Voltage Dip with Passive Crowbar
Matlab-Simulink, t_step = 0.5e-7, T_ref =0.5 p.u., w_ref = 1.067 p.u., Voltage dip 35% Un
1.5
Stator voltage A - phase
Rotor voltage A - phase
DC-link voltage
vas var udc [p.u.]
1
0.5
0
-0.5
-1
-1.5
4.8
4.9
5
5.1
5.2
5.3
t [s]
Voltage dip applied
MCB open
5.4
Simulation Results - Voltage Dip with Passive Crowbar
3
Stator current A - phase
Rotor current A - phase
Electromagnetic torque
2.5
2
ias iar Te [p.u.]
1.5
1
0.5
0
-0.5
-1
-1.5
-2
4.8
4.9
5
5.1
t [s]
Voltage dip applied
5.2
5.3
MCB open
5.4
Conclusions
•
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.