David Larsson
Power-Gen Europe 2005
Milan, Italy
www.abb.com/FACTS
FACTS and HVDC
for Grid Connection
of Large Wind Farms
FACTS
Agenda
Î Wind
Generators
Î Response
PICTURE
© ABB
Date 25-Nov-04- 2 -
JPG-FORMAT
WEB OPTIMIZED
RESOLUTION
Î SVC
to Grid Faults
and STATCOM
Î HVDC
Î HVDC
Light®
Î Closing
Remarks
Generator
FACTS
turbine
The Double-fed Induction Generator
double-fed
induction
generator
∼
gearbox
grid
IG
© ABB
Date 25-Nov-04- 3 -
slip-rings
transformer
=
∼
∼
=
rectifier
inverter
Generator
FACTS
Equivalent Circuits (for Positive-sequence)
is
Shortcircuited
induction
generator
© ABB
Date 25-Nov-04- 4 -
xS
uS
uS
xR
rR /s
xm
is
Doublyfed
induction
generator
rS
rS
xS
xR
rR /s
xm
uR /s
Generator
FACTS
Magnetising of Rotor
stator flux
s≈0
conn
bus
rS
xS
rotor flux
xR
rR/s
xm
induction generators
weak network
s<<0
conn
bus
rS
xS
xR
© ABB
Date 25-Nov-04- 5 -
xm
weak network
induction generators
rR/s
Generator
FACTS
Typical Characteristics @ Fixed Rotor Flux
S ta tor curre nt (pu)
5
iS (pu)
4
3
2
1
0
-40
-30
-20
-10
0
10
20
30
40
50
20
30
40
50
Ele ctrical torque (pu)
3
Te l (pu)
2
1
0
-1
© ABB
Date 25-Nov-04- 6 -
-2
-3
-40
-30
-20
-10
0
10
rotor fre q (Hz)
Generator
FACTS
Mechanical System
Turbine
© ABB
Date 25-Nov-04- 7 -
Generator
FACTS
Agenda
Î Wind
Generators
Î Response
PICTURE
© ABB
Date 25-Nov-04- 8 -
JPG-FORMAT
WEB OPTIMIZED
RESOLUTION
Î SVC
to Grid Faults
and STATCOM
Î HVDC
Î HVDC
Light®
Î Closing
Remarks
Fault
FACTS
Recovery
Generic System
Wind
Farm
35 km
66 kV
SVC
© ABB
Date 25-Nov-04- 9 -
Main
Grid
Minor
Load
0.2 s. 3psg
at 1.0 s.
Fault
FACTS
Recovery
Fault Recovery, Without SVC
Stator & rotor flux
stator
rotor
1.2
per unit
1
0.8
0.6
0.4
0.2
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
4
4.5
5
Wind turbine & induction generator speed
turbine
generator
1.12
per unit
1.1
1.08
1.06
1.04
1.02
© ABB
Date 25-Nov-04- 10 -
1
0.98
0
0.5
1
1.5
2
2.5
time (s)
3
3.5
Fault
FACTS
Recovery
Fault Recovery, With SVC
Stator & rotor flux
stator
rotor
1.2
per unit
1
0.8
0.6
0.4
0.2
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
4
4.5
5
Wind turbine & induction generator speed
turbine
generator
1.12
per unit
1.1
1.08
1.06
1.04
1.02
© ABB
Date 25-Nov-04- 11 -
1
0.98
0
0.5
1
1.5
2
2.5
time (s)
3
3.5
FACTS
Agenda
Î Wind
Generators
Î Response
PICTURE
© ABB
Date 25-Nov-04- 12 -
JPG-FORMAT
WEB OPTIMIZED
RESOLUTION
Î SVC
to Grid Faults
and STATCOM
Î HVDC
Î HVDC
Light®
Î Closing
Remarks
SVC &
FACTS
STATCOM
Combined VSC and TSC Scheme
132 kV
150 MVA
© ABB
Date 25-Nov-04- 13 -
~
=
VSC
+/- 53 Mvar
FC
3 Mvar
TSC
94 Mvar
SVC Vs. STATCOM Comparison
SVC &
FACTS
STATCOM
SVC
STATCOM
- 100 / + 220 MVAR
- 90 / + 170 MVAR
XFMR
XFMR
220 MVAR
170 MVAR
© ABB
Date 25-Nov-04- 14 -
≅
HF
TCR
TSC
54 MVAR
- 154 MVAR
166 MVAR
HF
HF
20 MVAR
20 MVAR
VSC
VSC
± 65 MVAR
± 65 MVAR
Capacitive MVAR Output vs Voltage
1,0
0,9
0,8
0,7
Voltage (p.u.)
SVC -100 /+220
220
178
141
108
STATCOM -90 /+170
170
149
130
111
…each case is unique considering footprint,
transmission situation, losses, etc
SVC &
FACTS
STATCOM
Example SVC Installation, outline
220 kV
220/20 kV
200 MVA
© ABB
Date 25-Nov-04- 15 -
20 kV
TCR1
135 Mvar
TSC
5th
TCR2
135 Mvar 130 Mvar 40 Mvar
7th
30 Mvar
SVC &
FACTS
STATCOM
Example SVC Installation, Picture
Control
Building
TSC
Power
Transformer
TCR1
© ABB
Date 25-Nov-04- 16 -
TCR2
Filter
© ABB
Date 25-Nov-04- 17 -
SVC &
FACTS
STATCOM
Example SVC Installation, layout
FACTS
Agenda
Î Wind
Generators
Î Response
PICTURE
© ABB
Date 25-Nov-04- 18 -
JPG-FORMAT
WEB OPTIMIZED
RESOLUTION
Î SVC
to Grid Faults
and STATCOM
Î HVDC
Î HVDC
Light®
Î Closing
Remarks
FACTS
HVDC
Why HVDC? Part 1
© ABB
Date 25-Nov-04- 19 -
One reason for choosing a High Voltage Direct
Current (HVDC) trans-mission system for the
connection of an offshore wind farm might be a
long distance between the wind farm and the grid
connection point, where HVAC cables can not be
used due to their charging current.
FACTS
HVDC
Why HVDC? Part 2
An HVDC connection separates the two systems
electrically. As an example: A contingency in the
on shore grid doesn’t affect the voltage level at the
off-shore installation.
On-shore
Main Grid
Off-shore
Wind farm
© ABB
Date 25-Nov-04- 20 -
± 150kVDCcable
FACTS
HVDC
Why HVDC? Part 3
• It is possible to operate of the wind farm at
different and/or varying frequency, e.g. for
optimum use of the wind energy.
• Assuming VSC technology, both the off-shore
installation and the on-shore grid can be
supported with dynamic reactive power.
© ABB
Date 25-Nov-04- 21 -
• Lower resistive losses in the interconnecting
cable.
FACTS
Agenda
Î Wind
Generators
Î Response
PICTURE
© ABB
Date 25-Nov-04- 22 -
JPG-FORMAT
WEB OPTIMIZED
RESOLUTION
Î SVC
to Grid Faults
and STATCOM
Î HVDC
Î HVDC
Light®
Î Closing
Remarks
FACTS
HVDC Light®
© ABB
Date 25-Nov-04- 23 -
HVDC Light® is a DC transmission
system based on voltage source
converter (VSC) technology. In a
VSC, the current in the valves can be
switched on and off at any time - the
converter is self-commutated.
HVDC
FACTS
Light®
HVDC Light®
Valve:
IGBT + Diode
AC
PhaseReactance
DC-Cable
DC-Capacitor
+/- 150 kV
© ABB
Date 25-Nov-04- 24 -
ACFilter
DC-Cable
HVDC
FACTS
Light®
HVDC Light®, P-Q Characteristic
Limits
maximum Current
maximum DC Voltage
maximum DC Power
Q
Uac = 0.9 pu
Uac = 1.0 pu
Uac = 1.1 pu
© ABB
Date 25-Nov-04- 25 -
P
HVDC
FACTS
Light®
HVDC Light® Offshore Installation
HVDC Light® offshore
module, 250-300 MVA
(W×L×H) 30×40×20 m
© ABB
Date 25-Nov-04- 26 -
Including Transformer
FACTS
Agenda
Î Wind
Generators
Î Response
PICTURE
© ABB
Date 25-Nov-04- 27 -
JPG-FORMAT
WEB OPTIMIZED
RESOLUTION
Î SVC
to Grid Faults
and STATCOM
Î HVDC
Î HVDC
Light®
Î Closing
Remarks
FACTS
Conclusion 1
„ Both
AC and DC are available and feasible
for connecting large wind power plants to the
grid.
selection of technology depends on
several parameters, a supplier with
experience of both technologies should be
able to advice.
© ABB
Date 25-Nov-04- 28 -
„ The
FACTS
Conclusion 2
„ An
SVC at the PCC provide reactive power
support to the grid at all operating scenarios
and mitigates problems with flicker, stability
and other quality issues.
Light® is an alternative when the
connection is long and/or the grid connection
point is weak. With HVDC Light® it is possible
to operate of the wind farm at different and/or
varying frequency.
© ABB
Date 25-Nov-04- 29 -
„ HVDC