# Sathyabama University Previous Year Exam Papers Power system Analysis

PART – A (10 x 2 = 20)

Answer ALL the Questions

1. What is the need for system analysis in planning and operation of

power system?

2. How are the base value chosen in per unit representation of a

power system?

3. Draw the p equivalent circuit of a transformer with off nominal

tap ratio.

4. Define bus incidence matrix.

5. Mention two objectives of short circuit analysis.

6. Draw the zero sequence n/w of a star connected generator with

zero sequence impedance Zgo, when the neutral is grounded

through an impedance Zno.

7. What are the three classes of busses of a power system used in

power flow analysis? What are the quantities to be specified and

to be completed for each class during power flow solution?

8. Compare Gauss-Seidal method and Newton Raphson method

with respect to number of iterations taken for convergence and

memory requirement.

9. Define critical clearing time.

10. Write the power angle equation of a synchronous machine

connected to an infinite bus and also the expression for maximum

power transferable to the bus.

PART – B (5 x 12 = 60)

Answer All the Questions

11. Explain single line and reactance diagram of a power system.

Also explain the per unit system of analysis power system

problems and its advantages.

(or)

12. Explain in detail about the per phase analysis of symmetrical

three phase system.

13. Explain bus admittance and bus impedance matrix formation.

Discuss the p-equivalent circuit of transformer with off-nominal

tap-ratio.

(or)

14. Explain the modeling of generator, load and transmission line for

short circuit, power flow and stability.

15. Derive the formula for fault current, fault bus voltages and

current through the lines for a 3 phase symmetrical fault at a bus

in a power system using Z bus. State the assumptions made in

the derivation.

(or)

16. Explain the various objectives in short circuit analysis. Derive the

components of Z bus in sequence frame fault matrices.

17. (a) Discuss the procedure for representing a tap charging

transformer in the formation of system matrix (YBUS) for

load flow studies.

(b) Explain the procedure for calculating line flows and line

flows and line losses.

(or)

18. For the network shown in fig. obtain the complex bus bar voltage

at bus 2 at the end of first iteration. Use Gauss-Siedal method.

Line impedance shown in fig are in per unit.

Given: Bus 1 in black bus with V1 = 1.00°

= Ð °

= Ð °

=

+ = − +

V o

Assume V o and

V

P jQ j and

o 1

: 1.02

| | 1.02

5.96 1.46

2

3

3

2 2

o

19. (a) Derive the swing equation of a synchronous machine

connected to an infinite bus.

(b) Deduce the condition of equal area criterion for transient

stability analysis.

(or)

20. Explain the step wise procedure of determining the swing curve

of a synchronos machine connected to infinite bus through a

double circuit transmission line using modified Euler’s method.