3. A three phase, 345-kV, 60 Hz transposed line is composed of two ACSR, 1,113,0

Question

3. A three phase, 345-kV, 60 Hz transposed line is composed of two ACSR, 1,113,000 cmil, 45/7 Bluejay conductors per phase with flat horizontal spacing of 12 m. The conductors have a diameter of 3.195 cm and a GMR of 1.268 cm. The bundle spacing is 40 cm. The resistance of each conductor in the bundle is 0.0538 chms per km and the line conductance is negligible. The line is 150 km long. Using the nominal pi model and with the aid of a lineperf program option 5 developed by Saadat, determine the ABCD constant of the line.

Explanation / Answer

GMD = 3
q
(11)(11)(22) = 13:859 m
82 CONTENTS
GMRL =
q
(45)(1:268) = 7:5538 cm
GMRC =
q
(45)(3:195=2) = 8:47865 cm
L = 0:2
13:859
7:5538 £ 10¡2 = 1:0424 mH/Km
C =
0:0556
ln 13:859
8:47865£10¡2
= 0:010909 ¹F/Km
Z = (
0:0538
2
+ j2¼ £ 60 £ 1:0424 £ 10¡3)(150) = 4:035 + j58:947
Y = j(2¼60 £ 0:9109 £ 10¡6)(150) = j0:0006169
The ABCD constants of the nominal ¼ model are
A =
µ
1 + ZY
2
¶
=
µ
1 +
(4:035 + j38:947)(j0:0006169)
2
¶
= 0:98182 + j0:0012447
B = Z = 4:035 + j58:947
C = Y
µ
1 + ZY
4
¶
= j0:00061137
Using lineperf and option 5, result in
Type of parameters for input Select
Parameters per unit length
r (­), g (Siemens), L (mH), C (¹F) 1
Complex z and y per unit length
r + j*x (­), g + j*b (Siemens) 2
Nominal ¼ or Eq. ¼ model 3
A, B, C, D constants 4
Conductor configuration and dimension 5
To quit 0
Select number of menu ! 5
CONTENTS 83
When the line configuration and conductor specifications are entered, the following
results are obtained
GMD = 13.85913 m
GMRL = 0.07554 m GMRC = 0.08479 m
L = 1.04241 mH/Km C = 0.0109105 micro F/Km
Short line model
Z = 4.035 + j 58.947 ohms
Y = 0 + j 0.000616976 Siemens
ABCD =
•
0:98182 + j0:0012447 4:035 + j58:947
¡3:8399e ¡ 007 + j0:00061137 0:98182 + j0:0012447
¸

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