Power System Analysis
A transmission line is composed of ACSR conductors consiting of six
aluminum strands and one steel strand as seen in Figure 1. The diameter of ACSR
conductor is 6cm. Each aluminum strand
has a diameter of 2 cm.
a) Design a system where the
conductors of the transmission line
is spaced 120 cm in horizontal
plane and then find;
i. Inductance per conductor
ii. The loop inductance
iii. The loop reactance at 50 Hz.
Note: Neglect the effect of steel strand.
b) If a Bundling is going to be applied for the above line repeat the steps i., ii., iii.
given above for part a). if a bundle of two conductors and bundle of three
conductors is used and comment about the results.
c) For the line in part a) find;
a. Capacitance per conductor
b. Capacitve reactance reactance at 50 Hz.
c. If we have a bundling of two same conductors what will be the
Capacitance and Capacitve reactance at 50 Hz.
2) a) On the one line diagram given below (Figure 2) the three phase
generator has subtransient reactance of 15% the motors 1 and 2 are supplied over
55 km. Motors are rated 2.3 kV. Rated inputs to motors are 200MVA. For motor 1 X”
=20% and for motor 2 X”=15 %. Transformer T1 is 350MVA, 20 / 230 kV with
leakage reactance 15%. T2 is composed of three single phase transformers each
rated 127/13.2 kV, 100MVA with leakage reactance of 10%. Series reactance of
transmission line is 0.5 km. Generator ratings are base.
a) reactances of transformers
b) base impedance of transmission line
c) reactances of motors
d) draw the equivalent circuit diagram of the one line diagram
20 kV T1 T2
b) An interconnected generator Reactor system is shown in . Use the base
MVA 60 MVA. Find the fault current and fault MVA if V A 500kV 50 Hz 180 km long three phase overhead transmission line delivers 1600 MW at 475 kV and at 0.95 power factor leading to the receiving end at full load. Using nominal circuit calculate the;
a) ABCD parameters
b) Sending end voltage and current
c) Sending end power and power factor
d) Full load line losses and efficiency
e) Percent voltage regulation
f) What will be the value of characteristic impedance of the line?
g) Commment about the maximum Power that will be transferred.
z = R+ j 0.335 km , y = j 4.807 x 10-6 S/km
Note: Conductors are ACSR 1113- kcmil Finch. Assume 50 °C temperature for the conductor to find resistance of this line.
If the Conductors were ACSR 954000 cmil Cardinal, assuming 50 °C temperature do you expect any change comment on your resuls.