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The apparent impedance of the TCSC (the impedance seen by the power system) can typically
be increased to up to 3 times the physical impedance of the capacitor, see figure
apparent reactance will mainly be used for damping of power oscillations.
en06000598.vsd
Imperatriz TCSC, Operating range
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
3.2
0
300
600
900
1200
1500
1800
2100
2400
2700
3000
Line current (Arms)
X
tc
s
c
/X
c
(
p
u
)
Continuous
30 min. overload
10s overload
Bypass mode
Series5
Continuous
30 min
10s
B
C
D
E
F
G
A
IEC06000598 V1 EN-US
Figure 93: Operating range of a TCSC installed for damping of power oscillations
(example)
During continuous valve bypass the TCSC represents an inductive impedance of about 20% of
the capacitor impedance. Both operation in capacitive boost mode and valve bypass mode can
be used for damping of power swings. The utilization of valve bypass increases the dynamic
range of the TCSC and improves the TCSC effectiveness in power oscillation damping.
7.1.2.9
Challenges in protection of series compensated and adjacent power lines
SEMOD168320-10 v2
System planning does not consider any more possible protection issues and difficulties, when
deciding for a particular, non conventional solution of certain operation and stability
problems. It is supposed that modern communication and state of the art computer
technologies provides good basis for the required solution. This applies also to protection
issues in series compensated networks. Different physical phenomena, which influence
conventional principles of IED protection, like distance protection, phase comparison
protection, are well known and accordingly considered in IED design. Some other issues, like
influence of controlled thyristors in series capacitor banks are getting increased importance,
although not as high as they would deserve.
The most important challenges, which influence the operation of different protection
functions in the greatest extent, are described in this chapter.
Voltage and current inversion
SEMOD168320-168 v2
Series capacitors influence the magnitude and the direction of fault currents in series
compensated networks. They consequently influence phase angles of voltages measured in
different points of series compensated networks and this performances of different
protection functions, which have their operation based on properties of measured voltage and
current phasors.
Voltage inversion
SEMOD168320-171 v2
Figure
presents a part of series compensated line with reactance X
L1
between the IED point
and the fault in point F of series compensated line. The voltage measurement is supposed to
1MRK 505 343-UEN B
Section 7
Impedance protection
163
Application manual
Содержание Relion 670 series
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