# Sathyabama University Question Papers BE

## Power system Analysis Fifth Sem

1. What is the need for system analysis in planning and operation of
power system?
2. What are the advantages of per unit system?
3. What is primitive matrix?
4. What is bus admittance matrix?
5. What is the reason for transients during short circuits?
6. Draw the equivalent sequence network for a line-line bolted fault
in a power system.
7. What is P-Q bus in power flow analysis?
8. What is the reason for transients during short circuits?
9. Write the swing equation and explain the term involved in it.
10. Give the expression for critical clearing time.

PART – B (5 x 12 = 60)
11. Draw the reactance diagram for the power system shown in
fig.11. Neglect resistance and use of 100MVA, 220Kv in 50W
line. The ratings of the generator, motor and transformer are
given below.
Generator : 40MVA, 25kV, X” = 20%
Synchronous motor : 50MVA, 11kV, X” = 30%
Y – Y Transformer : 40MVA, 33/220kV, X = 15%
Y – D Transformer : 30MVA, 11/220kV, (D/Y), X=15%
(or)
12. Draw the structure of an electrical power system and describe the
components of the system with typical values.
13. Find bus admittance matrix for the given network. Determine the
reduced admittance matrix by eliminating node 4. The values are
marked in p.u.
(or)

14. Find the bus impedance matrix for the reactance diagram is
shown in fig. all the impedances are marked in p.u.
15. A generator is connected through a transformer to a synchronous
motor. The subtransient reactance’s of generator and motor are
0.15 p.u and 0.35 p.u respectively. The leakage reactance of the
transformer is 0.1 p.u. All the reactances are calculated on a
common base. A three phase fault occurs at the terminals of the
motor when the terminal voltage of the generator is 0.9 p.u. The
output current of generator is 1 p.u. and 0.8 p.f leading. Find the
subtransient current in p.u. in the fault, generator and motor. Use
the terminal voltage of generator as reference vector.
(or)
16. Derive the expression for fault current in Line-to-line fault on an
unloaded generator in terms of symmetrical components.
17. Derive load flow algorithm using Gauss-Seidel method with flow
chart and discuss the advantages of the method.
(or)
18. Derive load flow algorithm using Newton-Raphson method with
flow chart and state the importance of the method.
19. Derive Swing equation used for stability studies in power system.
(or)
20. Explain the modified Euler method of analyzing multimachine
power system for stability, with neat flow chart.