en06000593.vsd
R
L1
jX
L1
-jX
C
Line 1
jX
L2
R
L2
Line 2
IEC06000593 V1 EN-US
Figure 88: 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 69)
Reduced costs of power transmission due to decreased investment costs for new power
line
SEMOD168320-88 v2
As shown in figure
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 upgrading of line protections on the
compensated as well as, adjacent lines should be considered. The main advantages of series
compensation against the new transmission line within the same corridor are:
•
Significantly reduced investment costs; the same increase in power transmission for up to
90% reduced costs
•
In many cases, the only practical way to increase the transmission capacity of a corridor
•
Series compensation shortens the lead times
•
Environmental impact
~
E
A
~
E
B
New transmission line
Series compensation
en06000594.vsd
IEC06000594 V1 EN-US
Figure 89: Series compensation is an important alternative to new transmission lines
Advancements in series compensation using thyristor switching technology
SEMOD168320-102 v3
A thyristor switched series capacitor (TSSC) can be used for power flow control. This is
performed by changing the reactance of the transmission circuit in discrete steps, as shown in
. A TSSC typically consists of a few segments in series that can be inserted
independently of each other in order to achieve different total series capacitor reactance.
1MRK 505 343-UEN B
Section 7
Impedance protection
161
Application manual
Summary of Contents for Relion 670 series
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