en06000595.vsd
Fw
Rv
-jX
C
Fw
Rv
-jX
C
Fw
Rv
-jX
C
IEC06000595 V1 EN-US
Figure 88:
Thyristor switched series capacitor
en06000596_ansi.vsd
-jX
C
Fw
Rv
jX
L
i
L
i
V
V
C
+
-
ANSI06000596 V1 EN-US
Figure 89:
Thyristor controlled series capacitor
I
L
Line current
I
V
Current through the thyristor
U
C
Voltage over the series capacitor
X
C
Rated reactance of the series capacitor
A thyristor controlled series capacitor (TCSC) allows continuous control of the series
capacitor reactance. This is achieved by adding current through the capacitor via the
parallel thyristor valve path see figure
. The main circuit of the TCSC consists of a
capacitor bank and a thyristor controlled inductive branch connected in parallel. The
capacitor bank may have a value of for example, 10...30 Ω/phase and a rated
continuous current of 1500...3000 A. The capacitor bank for each phase is mounted on
a platform providing full insulation towards ground. The thyristor valve contains a
string of series connected high power thyristors with a maximum total blocking voltage
in the range of hundreds of kV. The inductor is an air-core reactor with a few mH
inductance. The wave forms of a TCSC in capacitive boost mode are shown in figure
Section 8
1MRK 504 163-UUS A
Impedance protection
212
Transformer protection RET670 2.2 ANSI
Application manual
Summary of Contents for RELION RET670
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