FACTS
Flexible AC Transmission
System
Presented by:
Dr Ahmed Massoud
Dr Ahmed Massoud
University of Strathclyde
1
FACTS
1.
2.
3.
4.
5.
6.
7.
8.
POWER SYSTEMS
FACTS definition
FACTS controllers
Parallel controllers
Series controller
Series-parallel controllers
HVDC
Others
Dr Ahmed Massoud
University of Strathclyde
2
POWER SYSTEM
GENERATION
Dr Ahmed Massoud
TRANSMISSION
University of Strathclyde
DISTRIBUTION
3
Characteristics of Transmission
Bottlenecks
•
•
•
•
•
Steady-State Power Transfer Limit
Voltage Stability Limit
Transient Stability Limit
Thermal Limit
Short-Circuit Current Limit
Dr Ahmed Massoud
University of Strathclyde
4
Conventional System Solutions to
enhance Transmission capability
•
•
•
•
•
Series Capacitors (X)
Switched Shunt-Capacitor and Reactor (V)
Transformer LTC’s (V)
Phase Shifting Transformers (δ)
Synchronous Condensers (V)
Dr Ahmed Massoud
University of Strathclyde
5
FACTS
1.
2.
3.
4.
5.
6.
7.
8.
POWER SYSTEMS
FACTS definition
FACTS controllers
Parallel controllers
Series controller
Series-parallel controllers
HVDC
Others
Dr Ahmed Massoud
University of Strathclyde
6
Flexible Alternating Current
Transmission Systems (FACTS)
FACTS
AC transmission systems incorporating the
power
electronic-based
to
enhance
controllability and increase power transfer
capability.
FACTS Controllers
A power electronic based system & other
static equipment that provide control of one
or more AC transmission parameters.
Dr Ahmed Massoud
University of Strathclyde
7
Power Electronics Devices For
FACTS Controllers
Line-Commutated
• Thyristors
• Electrically Triggered (ETT)
• Light Triggered (LTT)
Self-Commutated
• Gate-Turn Off Thyristors (GTO)
• Insulated Gate Bipolar Transistors (IGBTs)
• Integrated Gate Commutated Thyristors (IGCTs)
Dr Ahmed Massoud
University of Strathclyde
8
FACTS
1.
2.
3.
4.
5.
6.
7.
8.
POWER SYSTEMS
FACTS definition
FACTS controllers
Parallel controllers
Series controller
Series-parallel controllers
HVDC
Others
Dr Ahmed Massoud
University of Strathclyde
9
FACTS
c o n tro lle rs
lin e
c o m m u ta te d
S e rie s
fo rc e d
c o m m u ta te d
Shunt
thy ris to r c o ntro lle d thy ris to r c o ntro lle d
s e rie s c a pa c ito r
re a c to r o r s w itc he d
(TC S C )
c a pa c ito r (TC R or TS C )
B a c k -to -b a c k S e rie s -s e rie s
c o nv e ntio na l HVD C inte rline po w e r flo w
c o ntro lle r
(IP F C )
S e rie s
Shunt
s ta tic s y nc hro no us
s e rie s c o m p e ns a to r
(S S S C )
s ta tic s y nc hro no us
c o mpe ns a to r
(S TATC O M )
S h u n t-S e rie s S e rie s -s e rie s
unifie d po w e r flo w
c o ntro lle r
(UP F C )
B a tte ry e ne rgy
s to ra ge (B E S S )
inte rline po w e r flo w
c o ntro lle r
(IP F C )
S upe rc o nduc ting
M a gne tic E ne rgy
S to ra ge (S M E S )
B a c k -to -b a c k
light HVD C
Dr Ahmed Massoud
University of Strathclyde
10
___
___
Vs
Vr
X
Vs .Vr
P=
sin δ
X
Vs
I.X
δ
I
Dr Ahmed Massoud
Vr
University of Strathclyde
11
Controllable parameters
Control of the line impedance
current and active power control
Control of angle
current and active power control
Series voltage injection
Current, active, and reactive power control
Parallel voltage injection
Current, active, and reactive power control
Dr Ahmed Massoud
University of Strathclyde
12
Series control
V1
Xseries
V2
X
Vseries
V1
P=V 1.V 2.sin(δ )/(X-X series )
δ
Dr Ahmed Massoud
University of Strathclyde
I
V2
13
Parallel control
V1
V2
X
V1
V1
Q
I
P=V 1.V 2.sin(δ )/X
Dr Ahmed Massoud
δ
University of Strathclyde
I
V2
14
Series and parallel control
V1 Xseries
X
V2
Vseries
Q
Dr Ahmed Massoud
?
University of Strathclyde
15
FACTS
1.
2.
3.
4.
5.
6.
7.
8.
POWER SYSTEMS
FACTS definition
FACTS controllers
Parallel controllers
Series controller
Series-parallel controllers
HVDC
Others
Dr Ahmed Massoud
University of Strathclyde
16
Static VAR compensator
•
•
•
•
•
•
•
TCR = Thyristor Controlled Reactor
TSR = Thyristor Switched Reactor
TSC = Thyristor Switched Capacitor
MSC = Mechanically-Switched Capacitor
MSR = Mechanically-Switched Reactor
FC = Fixed Capacitor
Harmonic Filters
Dr Ahmed Massoud
University of Strathclyde
17
Thyristor Controlled Reactor (TCR)
Parallel-connected static var generator or
absorber
● Output is adjusted to exchange capacitive or
inductive current
● Maintain or control specific parameters of the
electrical power system
(typically bus voltage).
● Thyristor-based Controllers
● Lower cost alternative to STATCOM
Dr Ahmed Massoud
University of Strathclyde
18
Thyristor Controlled
Reactor
8
Voltage
6
Current
4
2
0
-2
-4
-6
-8
0
0.005
0.01
Time (s)
0.015
0.02
Firing angle of 90
1
0.667
0.333
0
-0.333
-0.667
-1
0
0.005
0.01
Time (s)
0.015
0.02
Firing angle of 135
Dr Ahmed Massoud
University of Strathclyde
19
Thyristor Switched Capacitor (TSC)
Dr Ahmed Massoud
University of Strathclyde
20
Static Synchronous Compensator
(STATCOM)
● Parallel-connected static var compensator
● Capacitive or inductive output current
controlled independently of the ac
system voltage
Dr Ahmed Massoud
University of Strathclyde
21
Inverter
(IGBT, GTO, or GCT)
L
Q
Vdc
P (if no energy
source is provided)
Dr Ahmed Massoud
University of Strathclyde
22
Parallel Active Power Filters
(Parallel APF)
•
•
•
•
•
Reactive power
Compensation
Source current’s higher
Harmonics compensation
DC element voltage control
Dr Ahmed Massoud
University of Strathclyde
23
3-phase
supply
is
L
e
if
iL
v Shunt active
filter
non-linear
load
Shunt active power filter single line diagram
Dr Ahmed Massoud
University of Strathclyde
24
i dc (t)
Sa
v dc (t)
+ C
_
Sb
Sc
v an
Lb
v bn
S'a
La
S'b
Lc
v cn
S'c
ia
ib
ic
ea
eb
ec
Two level voltage source inverter
Dr Ahmed Massoud
University of Strathclyde
25
Dr Ahmed Massoud
University of Strathclyde
26
Voltage source inverters
1. Two level Voltage source inverter
2. Multilevel voltage source inverter
3. Series connection
Current source inverter ?
Dr Ahmed Massoud
University of Strathclyde
27
Multilevel inverter
1. Neutral point clamped
2. Cascaded
3. Flying capacitor
Dr Ahmed Massoud
University of Strathclyde
28
Neutral point clamped
Dr Ahmed Massoud
University of Strathclyde
29
Flying capacitor
Dr Ahmed Massoud
University of Strathclyde
30
Cascaded
Dr Ahmed Massoud
University of Strathclyde
31
2E volt
S1
i load
E
D1
i load
E
D4
S4
2E
2E
D5
S5
E
E
D8
S8
iload <0
iload >0
Dr Ahmed Massoud
University of Strathclyde
32
E volt
i load
E
D3
i load
E
D4
S3
S4
E
E
D5
S5
E
E
D8
S8
iload >0
Dr Ahmed Massoud
iload <0
University of Strathclyde
33
0 volt
i load
E
D3
i load
E
S3
S4
D4
0
0
E
E
D7
S7
S8
iload <0
iload >0
Dr Ahmed Massoud
D8
University of Strathclyde
34
-E volt
i load
E
D3
i load
E
S3
S4
D4
-E
-E
S6
D6
E
E
S7
D7
iload <0
iload >0
Dr Ahmed Massoud
University of Strathclyde
35
-2E volt
D2
E
S2
i load
E
i load
S3
D3
-2 E
-2 E
S6
D6
E
E
S7
D7
iload <0
iload >0
Dr Ahmed Massoud
University of Strathclyde
36
Output of 5-level inverter (PWM)
M a gni tu de (P er unit )
3
2
1
0
-1
-2
-3
0
Dr Ahmed Massoud
0. 005
0 .0 1
Ti me (s )
University of Strathclyde
0.015
0 .0 2
37
Series connection of IGBT
Dr Ahmed Massoud
University of Strathclyde
38
Output of two-level inverter (PWM)
M ag n itu d e (Per u n it )
3
2
1
0
-1
-2
-3
0
Dr Ahmed Massoud
0. 0 05
0 .0 1
T im e (s )
University of Strathclyde
0 .0 1 5
0 . 02
39
FACTS
1.
2.
3.
4.
5.
6.
7.
8.
POWER SYSTEMS
FACTS definition
FACTS controllers
Parallel controllers
Series controller
Series-parallel controllers
HVDC
Others
Dr Ahmed Massoud
University of Strathclyde
40
Series Capacitors Applied For:
Increasing Power Transfer
Increasing Stability Limits
Improving Voltage Profile
Improving Load Division
Dr Ahmed Massoud
University of Strathclyde
41
Series Active Power filter (Series
APF)
• Voltage harmonics compensation
• Stability improvement
• Current harmonics blocking
Dr Ahmed Massoud
University of Strathclyde
42
Static Synchronous Series
Compensator (SSSC)
● Output voltages in quadrature with, and
controllable independently of, the line current
● Control the transmitted electric power.
● May include energy storage to enhance the
dynamic behavior of the power system by
additional
temporary
real
power
compensation, to increase or decrease
momentarily, the overall real (resistive)
voltage drop across the line.
Dr Ahmed Massoud
University of Strathclyde
43
Thyristor Controlled Series
Capacitor (TCSC)
● Smooth control of series capacitive
reactance
Dr Ahmed Massoud
University of Strathclyde
44
FACTS
1.
2.
3.
4.
5.
6.
7.
8.
POWER SYSTEMS
FACTS definition
FACTS controllers
Parallel controllers
Series controller
Series-parallel controllers
HVDC
Others
Dr Ahmed Massoud
University of Strathclyde
45
Unified Power Flow Controller
(UPFC)
● A combination of STATCOM and SSSC coupled via a
common dc link
● Bi-directional flow of real power between the SSSC and
the STATCOM
Unified Power Flow Controller = Static Synchronous Series Compensator +
STATCOM
Dr Ahmed Massoud
University of Strathclyde
46
In v e r t e r
(I G B T , G T O , o r G C T )
S e r ie s
c o n v e rte r
C
S hunt
c o n v e rte r
Dr Ahmed Massoud
L
University of Strathclyde
47
Unified Power Quality
Conditioner (UPQC)
•
•
•
•
•
Source current harmonics compensation
System stability improvement
Reactive power compensation
DC element voltage control
Voltage harmonics compensation
Dr Ahmed Massoud
University of Strathclyde
48
Combination of active power filter
and passive filter
Supply
Load
Active
filter
Passive
filter
Parallel active power filter and passive filter
Dr Ahmed Massoud
University of Strathclyde
49
Supply
Load
Passive
filter
Active
filter
Parallel active power filter in series with passive filter
Dr Ahmed Massoud
University of Strathclyde
50
Supply
Active
filter
Load
Passive
filter
Series active power filter and parallel passive filter
Dr Ahmed Massoud
University of Strathclyde
51
Supply
Active
filter
Load
Active
filter
Series and parallel active power filter (unified power
quality conditioner UPQC)
Dr Ahmed Massoud
University of Strathclyde
52
Series VS. Parallel
● Series is more powerful in controlling the
current/power flow and damp oscillations
● Parallel is more effective in voltage control and
damping of voltage oscillations
Dr Ahmed Massoud
University of Strathclyde
53
FACTS
1.
2.
3.
4.
5.
6.
7.
8.
POWER SYSTEMS
FACTS definition
FACTS controllers
Parallel controllers
Series controller
Series-parallel controllers
HVDC
Others
Dr Ahmed Massoud
University of Strathclyde
54
FACTS and HVDC
Grid 1
Dr Ahmed Massoud
V1
FACTS
or
HVDC
University of Strathclyde
V2 Grid 2
55
High voltage DC transmission (HVDC)
It is economically attractive:
• over a long distance from a remote
generating to the load centre (>300
miles)
• underwater transmission
• when connecting two AC systems at two
different frequencies
Dr Ahmed Massoud
University of Strathclyde
56
Advantages of HVDC
•
•
•
•
•
•
•
•
•
•
No limits in transmitted distance.
Fast control of power flow, which implies stability
improvements.
Direction of power flow can be changed very quickly.
HVDC can carry more power for a given size of conductor
improved transient stability
dynamic damping of the electric system oscillations
Require less space compared to ac for same voltage rating
and size
Ground can be used as a return conductor
No charging current
HVDC transmission limits short circuit currents
Dr Ahmed Massoud
University of Strathclyde
57
Cost
AC Cost
DC Cost
600-800Km
Distance
Dr Ahmed Massoud
University of Strathclyde
58
The HVDC technology
The fundamental process that occurs in an HVDC system
is the conversion of electrical current from AC to DC
(rectifier) at the transmitting end, and from DC to AC
(inverter) at the receiving end.
1. Natural Commutated Converters. The component that
enables this conversion process is the thyristor (high
power and low switching frequency).
2. Forced Commutated Converters. It uses GTO or IGBT.
They are known as VSC (Voltage Source Converters).
Dr Ahmed Massoud
University of Strathclyde
59
HVDC transmission system
Terminal A
Positive pole
12 pulse
AC
system
A
AC filter and
power factor
correction
capacitors
Negative pole
12 pulse
Dr Ahmed Massoud
Ld
Y
Y
Δ
Y
Y
Y
Δ
Y
DC
filter
HVDC
transmission
line
Terminal B
AC
system
B
DC
filter
Ld
University of Strathclyde
60
Components of HVDC
1.
2.
3.
Converter: at one side rectifier and the other inverter
each converter consists of a positive pole and a
negative pole each pole consists of 6 pulse converters
connected through star-delta and star-star transformer
to yield 12 pulse converter
On the AC side:
* AC filters to reduce the current harmonics
generated from the converters
* Power factor correction capacitors to supply the
lagging reactive power
On the DC side: smoothing reactor and DC filters to
filter the ripple in the DC currents
Dr Ahmed Massoud
University of Strathclyde
61
12 pulse line frequency converter
Objectives:
1. Reduce current harmonics on AC side
2. Reduce voltage ripple on DC side
3. High power
12 pulse converter consists of two six-pulse converters
connected through star-star and delta-star transformer
The 2 converters are connected in series from the DC side
and parallel from the AC side
Dr Ahmed Massoud
University of Strathclyde
62
Id
ia
i a1
2N:1
cs1
i a2
i as1
as1
v d1
n1
bs1
as2
2 3 N:1
Ld
i as2
v d2
cs2
n2
bs2
Dr Ahmed Massoud
University of Strathclyde
63
Types of HVDC links
1. Monopolar: Having one conductor and the ground is
the return path
DC pole
return earth
Dr Ahmed Massoud
University of Strathclyde
64
2. Bipolar: There are two conductors (poles). One
operates with positive polarity and the second with
negative. During fault of one them, the bipolar acts as a
monopolar
+ DC pole
return earth
- DC pole
Dr Ahmed Massoud
University of Strathclyde
65
HVDC Light
1. HVDC Light unit sizes range from a few tens of MW to
presently 350 MW and for DC voltages up to ±150 kV and
units can be connected in parallel.
2. HVDC Light consists of two elements: converter stations
and a pair of cables. The converter stations are Voltage
Source Converters (VSCs) employing Self-commutated
switch
Dr Ahmed Massoud
University of Strathclyde
66
FACTS
1. POWER SYSTEMS
2. FACTS definition
3. FACTS controllers
4. Parallel controllers
5. Series controller
6. Series-parallel controllers
7. HVDC
8. Others
Battery Energy Storage System
Super conducting material
Dr Ahmed Massoud
University of Strathclyde
67