Sathyabama University 2010 B.E Electrical and Electronics Engineering Power system analysis - Question Paper

PART – A (10 x two = 20)(twenty marks)

ans All the ques.

1. Define per unit value of volume.

2. Write the formula to compute the base current/phase of a 3 phase system.

3. What is the need for load flow study?

4. What is the significance of more number of zeroes in the bus admittance matrix?

5. List the unsymmetrical faults.

6. Write the complex power formula in term of symmetrical equivalent.

7. Define slack bus.

8. What is meant by load flow study?

9. Describe equal area criterion.

10. Write the state variable form of swing formula to solve it using replaced Euler method.


PART – B (5 x 12 = 60)(sixty marks)


ans All the ques.

11. A 3 phase Delta-star transformer with rating 100 KVA, 11 Kv/400 V has its primary and secondary leakage reactance as 12 ohm/phase and 0.05 ohm/phase respectively. compute the per unit reactance of transformer with respect to H.V and L. V. and provide commands.
(or)
12. Write short notes on :
(1) Steady state and transient state
(2) Need for power system analysis
(3) Short circuit and stability analysis

13. Derive the algorithm for symmetrical short circuit analysis using bus impedance matrix. State assumption if any.
(or)
14. Figure indicates a four bus system. The shunt admittances at the buses are negligible . The line impedance are provided below:
Line 1-2 2-3 3-4 1-4
R pu 0.025 0.02 0.05 0.04
X pu 0.10 0.08 0.20 0.16




(i) presume dotted line is not. Formulate Y bus.
(ii) Which elements Y bus found above are affected when line 1-3 added?
(iii) If line 1-3 has 0.1 + j0.4 pu as impedance, obtain Y bus when it is added.

15. (a) Distinguish ranging from symmetrical and unsymmetrical faults
(b) List the steps in symmetrical fault computations.
(or)
16. A three phase, 6.9 kV, 10 MVA alternator has X" = X2=15% and X0=5%. The neutral is grounded through a reactor of 0.381 ohm. obtain the sub transient current in the faulted phase, when a single line to ground fault takes place.Also draw its sequence network inter connection diagram.

17. Explain Gauss-Seidal method of Load flow study with the help of neat flow chart.
(or)
18. Compare the performance of Gauss-Seidal method and Newton Raphson method for load flow solution using nodal admittance approach for the formulation of load flow equations with suitable examples.

19. Explain the use of equal area criterion to study the transient stability analysis of a fault occurs at the middle of 1 of the lines in parallel circuit feeding an infinite bus and is subsequently cleared by opening of faulted line. Also find the critical clearing angle in this case.
(or)
20. Explain the algorithmic steps to find the solution of swing formula by Runge-Kutta method.

Earning:   Approval pending.