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Increase in power transfer
SEMOD168320-45 v2
The increase in power transfer capability as a function of the degree of compensation for a
transmission line can be explained by studying the circuit shown in figure
transfer on the transmission line is given by the equation
:
( )
( )
(
)
sin
sin
1
d
d
×
×
×
×
=
=
-
× -
A
B
A
B
Line
C
Line
C
U
U
U
U
P
X
X
X
K
EQUATION1897 V1 EN-US
(Equation 68)
The compensation degree K
c
is defined as equation
A
B
-jX
C
P
A
Q
A
P
B
Q
B
U
A
U
B
U
+jX
L
U
A
U
B
d
D
en06000590.vsd
IEC06000590 V1 EN-US
Figure 86: Transmission line with series capacitor
The effect on the power transfer when considering a constant angle difference (δ) between
the line ends is illustrated in figure
. Practical compensation degree runs from 20 to 70
percent. Transmission capability increases of more than two times can be obtained in practice.
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 87: 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
Section 7
1MRK 505 343-UEN B
Impedance protection
160
Application manual
Summary of Contents for Relion 670 series
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