Question

1- 30-kV, three-phase transmission line has a per phase series impedance of z = 0.05+j0.45 ohm per Km and a per phase shunt admittance of y = j3.4x10-6
siemens per km. The line is 80 km long.
Using the nominal π
model, determine
a The transmission line ABCD constants.
b Find the sending end voltage and current,
voltage regulation, the sending end power
and the transmission efficiency when the line
delivers
1. 200 MVA, 0.8 lagging power factor at 220 kV
2. 306 MW, unity power factor at 220 kV.

2-A 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