facts and hvdc systems in power engineering
TRANSCRIPT
FACTS and HVDC systems in
Power Engineering
AE1M15PRE
2
What is FACTS?
• FACTS = Flexible AC Transmission Systems
• IEEE:
– FACTS: Alternating current transmission systems
with static regulator integrated or based on high
power electronic technology. Used for power flow
control and transmission line capacity increasing.
– FACTS controller: Unit with high power electronic or
static, which allows controlling of one or several
parameters of AC transmission system.
3
Power transmission
• Limits
– thermal (current)
– dialectical (voltage)
– stability (static and
dynamic)
• Power flow control
– Line impedance X
– Load angle d
– Voltage U, j
– Injection of P,Q
121
2 PsinX
UUP d
I XU
2U
1
P1+jQ
1 P2+jQ
2
X
Ucos
X
UUQ
2
2212 d
4
Power flow
I
U1
U2d
j2
j2
jXII X
U2
U1
P1+jQ
1 P2+jQ
2
222 cosIUP j
dj sinUcosXI 12
dj sinX
UcosI 1
2 121
2 PsinX
UUP d
5
Power flow
I
U1
U2d
j2
j2
jXI
I XU
2U
1
P1+jQ
1 P2+jQ
2
222 sinIUQ j
dj cosUUsinXI 122
X
Ucos
X
UsinI 21
2 dj
X
Ucos
X
UUQ
2
2212 d
2
21 XIQQ
d
d
cosUU2UUX
1
X
Ucos
X
UUQ
21
2
2
2
1
2
2211
d cosX
UU
X
UQ 21
2
11
6
P-Q transmission diagram
d sinX
UUP 21
2
X
Ucos
X
UUQ
2
2212 d
I XU
2U
1
P1+jQ
1 P2+jQ
2
2
21
22
22
2
2X
UU
X
UQP
dd
X
UUr
X
US 21
2
2 ,,0circle
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Control principles - passive
• Shunt
• Series
8
Control principles - active
• Shunt
• Series
9
Convertors
• Thyristor unit
• Three phase
convertors (VSC)
10
Voltage Source Convertor(VSC)
• Switching element (GTO, IGBT, IGCT)
• Pulse Width Modulated (PWM) –Umax,j,50 Hz
• High harmonics filters
• DC circuit – high capacity C or DC source
– C – I orthogonal to U only Q control
– source – any phase shift P,Q control
• Connected to the line through transformer
– shunt – ind., cap. current U regulation
– series – voltage injection P,Q regulation
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FACTS
1) series 3) combined (universal)
2) shunt U
Line
I
Line
I
Line
U
DC
12
FACTS
• Shunt
TSC – Thyristor Switched Capacitor
TCR – Thyristor Controlled Reactor
13
FACTS
• Shunt
SVC – Static Var Compensator
STATCOM – Static Synchronous Compensator
VSC
DC
14
FACTS
• Series SSSC – Static Synchronous Series Compensator
TCSC – Thyristor Controlled Series Capacitor
VSC
DC
15
FACTS
• Universal
UPFC – Unified Power Flow Controller
DC
16
Application
• Power flow control (P,Q)
• Transmission lines capacity improvement
(thermal limits)
• Safety rise (higher stability limits, short
circuit currents and overload reduction,
oscillation damping)
• Voltage control
• Controllable values (U, I, X, P, Q )
interconnected, some are dominant
17
Benefits
• Fast response to the demand
• Frequent change in output
• Continuously adjustable output
18
Admittance model
• suitable for thyristor controlled convertors
19
Model TCR
0,0
0,2
0,4
0,6
0,8
1,0
90 100 110 120 130 140 150 160 170 180
BT
CR(a
) (
p.u
.)
a ( )
aaaa
a
sincos32cos22BB LTCR
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Model SVC, TCSC
-0,40
-0,20
0,00
0,20
0,40
0,60
0,80
1,00
90,0 100,0 110,0 120,0 130,0 140,0 150,0 160,0 170,0 180,0
B(a
) (p
.u.)
a ( )
C
1L
CLTCR Bsincos32cos22
BB aaaa
a
21
Model SVC, TCSC
-20,0
-15,0
-10,0
-5,0
0,0
5,0
10,0
15,0
20,0
90,0 100,0 110,0 120,0 130,0 140,0 150,0 160,0 170,0 180,0
X(a
) (p
.u.)
a ( )
induktivní mód činnosti
kapacitníní mód činnosti
rezonance
• Resonance (TCSC) aaaaa resres
Inductive mode
Capacitive mode
22
TCSC
0,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
0,0 30,0 60,0 90,0 120,0 150,0 180,0
PS
(p.u
.)
d ( °)
without compensation
with compensation XTCSC = XCmin.
with compensation XTCSC = XCmax.
23
Power characteristics - TCSC
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Power characteristics - TCSC
0,0
0,5
1,0
1,5
2,0
2,5
3,0
0,0 30,0 60,0 90,0 120,0 150,0 180,0
QS
(p.u
.)
d ( °)
without compensation
with compensation XTCSC = XCmin.
with compensation XTCSC = XCmax.
25
SVC
26
Power characteristics - SVC
0,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
0,0 30,0 60,0 90,0 120,0 150,0 180,0
PS
(p.u
.)
d ( °)
without comp.
with comp. XCmax.
with comp.XLmax.
27
Power characteristics - SVC
0,0
0,5
1,0
1,5
2,0
2,5
3,0
0,0 30,0 60,0 90,0 120,0 150,0 180,0
QS
(p.u
.)
d ( °)
without comp.
with comp.XLmax.
with comp. XCmax.
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SSSC
• Power flow control
• Oscillation damping
• Transmission stability
improvement
• Voltage stability
improvement
29
SSSC
• Power flow regulation
(generation or
absorption of Q),
Upq ILine
• Injection of Upq XL,
XC in series with line
• DC source
– P supply Rline
compensation
30
SSSC
• Inductive mode
– Upq in phase with
drop UL XL
– Upq < UL else
reverse power flow
31
SSSC
Without regulation
With regulation
32
STATCOM
• Voltage value and
curve control
• Stability limits and line
capacity improvement
• Oscillation damping
• Load symmetrisation
• Voltage stability and
quality improvement
• Transmission,
distribution and
industrial application
33
STATCOM
• Voltage regulation
(load,U ; load, U),
line capacity rise P,
stability improvement
• Capacity C P
consumed to cover
losses in switches
– P low
IAC ± 90 from UAC
34
STATCOM
• Q regulation – amplitude Uout
– Uout > UAC injection Q to the system (C mode)
– Uout < UAC consumption Q (L mode)
• P regulation – by angle between Uout and UAC
a) P = 0 b) P from grid c) P to grid
35
STATCOM
Without
regulation
With
regulation
36
UPFC = STATCOM + SSSC
37
UPFC
38
UPFC
• U, P, Q regulation
– QSH, QSER independent control
– P flows from VSC1 to VSC2 (and other way)
→ performance area is circuit
– Independent control U1, U2, X, d
• VSC2
– 0 ≤ USE ≤ USEmax, 0 ≤ jSE ≤ 2, f = 50Hz
– P, Q both ways
• VSC1
– P consumption for VSC2 + losses, Q both ways
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UPFC in the grid
• At the beginning of transmission lain is
placesed
– Operates as 2 voltage sources with variable voltage
amplitude and phase
40
UPFC – performance regimes
• Regimes : 1. Voltage regulation
2. Series compensation
3. Voltage phase control
4. Power flow control
41
UPFC – power flow control
2
2SE2
2SESE
2
2SESEX
UUQ,QP,P
djddjd
42
PST
• Phase-shifting transformer
• Active power flow control
43
PST quadrature-boosting
transformers (QBT)
phase-angle regulators (PAR)
44
HVDC
• Long-distance
transmission
• Interconnection of
power systems
• Submarine cables
• Distant sources
connection
• City and power
islands supply
• thyristors x IGBT
45
Conclusion
• FACTS = high power electronic equipment
for voltage and power control
• Lot of kinds with different properties and
characteristics
• Improve stability and reliability of
transmission system
• Numbers of applications x high price