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IEC06000592-2-en.vsd
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
1
1.5
2
2.5
3
3.5
Degree of series compensation [%]
In
c
re
a
se
i
n
p
o
we
r
tr
a
n
s
fe
r
Power transfer with constant angle difference
Degree of
compensation
Multiple of power over
a non-compensated line
IEC06000592 V2 EN-US
Figure 72:
Increase in power transfer over a transmission line depending on
degree of series compensation
Active load sharing between parallel circuits and loss reduction
SEMOD168320-79 v2
A series capacitor can be used to control the distribution of active power between
parallel transmission circuits. The compensation of transmission lines with
sufficient thermal capacity can relieve the possible overloading of other parallel
lines. This distribution is governed by the reactance, while the losses are
determined by the resistance. A properly designed series compensation system can
considerably reduce the total transmission system losses, as shown in figure
en06000593.vsd
R
L1
jX
L1
-jX
C
Line 1
jX
L2
R
L2
Line 2
IEC06000593 V1 EN-US
Figure 73:
Two parallel lines with series capacitor for optimized load sharing
and loss reduction
To minimize the losses, the series capacitor must be installed in the transmission
line with the lower resistance. The size of the series capacitor that minimizes the
total losses is given the following expression:
1
1
2
2
-
=
L
C
L
L
L
X
X
R
X
R
EQUATION1899 V1 EN-US
(Equation 48)
Reduced costs of power transmission due to decreased investment
costs for new power line
SEMOD168320-88 v2
the line loading can easily be increased 1.5-2 times by series
compensation. Thus, the required number of transmission lines needed for a certain
power transfer can be significantly reduced. The cost of series compensation is
small compared to the cost of a transmission line. When evaluating the cost of a
transmission system upgrade also the cost of secondary equipment such as eventual
Section 8
1MRK 506 369-UEN B
Impedance protection
166
Line distance protection REL670 2.2 IEC
Application manual
Содержание REL670 2.2 IEC
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