Question

1- A 69-kV, three-phase short transmission
line is 16 km long. The line has a per
phase series impedance of 0.125 +
j0.4375 ohm per km. Determine the sending
end voltage, voltage regulation, the
sending end power, and the transmission
efficiency when the line delivers
a. 70 MVA, 0.8 lagging power factor at 64 kV
b. 120 MW, unity power factor at 64 kV

2-three-phase, completely transposed 345-kV, 200 km line has two 795,000-
cmil 26/2 ACSR conductor per bundle and
the following line constants of
z
= 0.032+j0.35 ohm/km and y=j4.2x10-6 S/km.
Full load at the receiving end is 700 MW
at 0.9 pf leading and at 95% of rated
voltage. Determine the following:
a. ABCD parameters of the nominal
π
b. Sending end voltage
Vs, current
IS, and real
power
Ps
c. Percent voltage regulation
d. Transmission-line efficiency at full load.

Answer 1