Increase In Power Transfer - ABB REL670 2.2 IEC Applications Manual

1MRK 506 369-UEN B
8.13.3.2
Line distance protection REL670 2.2 IEC
Application manual
A
Z
SA1
~
E
A
Seires
capacitor
IEC06000585 V1 EN-US
Figure 195: A simple radial power system
500
400
300
200
100
0 200 400 600 800
IEC06000586 V1 EN-US
Figure 196: Voltage profile for a simple radial power line with 0, 30, 50 and
70% of compensation

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 197. The power transfer on the transmission line is given by the
equation 360:
( )
d
× ×
U U sin
=
A B
P
-
X X
Line C
EQUATION1897 V1 EN-US
The compensation degree K
A
P
A
-jX
C
+jX
L
U
A
Q
A
IEC06000590 V1 EN-US
Figure 197: 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 198. Practical compensation degree
runs from 20 to 70 percent. Transmission capability increases of more than two
times can be obtained in practice.
B
Power line
Load
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U
limit
1000 1200 1400 1600 1800
P[MW]
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( )
d
× ×
U U sin
=
A B
( )
× -
X 1 K
Line C
is defined as equation
c
D
U U
U
A
B
P
B
U
B
Q
B
d
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Section 8
Impedance protection
GUID-C9163D4E-CC2B-4645-B2AC-2C8A3FE3D337 v3
B
(Equation 360)
375