ABB Relion 670 series - Page 182

Capacitive
Inductive
200
400
600
800
1000
200
400
600
Q
(Mvar)
500 1000 1500
Power flow
(MW)
(T.L.)
(S.C.)
(T.L.
+
S.C.)
Transmission
Line
Series
Compensation
500 kV
500 km
k = 50 %
en06000589.vsd
IEC06000589 V1 EN
Figure 72: Self-regulating effect of reactive power balance
Increase in power transfer
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 73. The power
transfer on the transmission line is given by the equation 50:
( ) ( )
( )
A B A B
Line C Line C
V V sin V V sin
P
X X X 1 K
d d × × × ×
= =
- × -
EQUATION1994-ANSI V1 EN (Equation 50)
The compensation degree K
c
is defined as equation 48
A B
-jX C
P
A
Q
A
P
B
Q
B
V
A
V
B
V
+jXL
V
A
V
B
en06000590_ansi.vsd
D
d
ANSI06000590 V1 EN
Figure 73: Transmission line with series capacitor
Section 8 1MRK 506 369-UUS -
Impedance protection
176 Line distance protection REL670 2.2 ANSI
Application manual