ABB RELION RET670 Applications Manual page 217

1MRK 504 163-UUS A
Transformer protection RET670 2.2 ANSI
Application manual
Reduced costs of power transmission due to decreased investment
costs for new power line
As shown in figure 85 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 Series compensation
A
New transmission line
IEC06000594 V1 EN-US
Figure 87: Series compensation is an important alternative to new transmission
lines
Advancements in series compensation using thyristor switching
technology
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 figure 88. 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.
Impedance protection
~
E
B
en06000594.vsd
Section 8
SEMOD168320-88 v2
SEMOD168320-102 v3
211