EE 2351 POWER SYSTEM ANALYSIS ANNA UNIVERSITY QUESTION PAPER, IMPORTANT QUESTIONS, 2 MARKS AND 16 MARKS QUESTIONS FOR EEE DEPARTMENT

ANNA UNIVERSITY QUESTION PAPER POWER SYSTEM ANALYSIS IMPORTANT QUESTIONS, 2 MARKS AND 16 MARKS QUESTIONS FOR EEE DEPARTMENT

B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2011

Sixth Semester

Electrical and Electronics Engineering

EE 2351 — POWER SYSTEM ANALYSIS

(Regulation 2008)

Time : Three hours Maximum : 100 marks

Answer ALL questions

PART A — (10 × 2 = 20 marks)1. Draw a simple per-phase model for a cylindrical rotor synchronous machine.

2. What are the advantages of per unit system?

3. What is Jacobian matrix?

4. What is a slack bus?

5. Mention the objectives of short circuit analysis.

6. Write down the balanced and unbalanced faults occurring in a power system.

7. What is sequence network?

8. Write the symmetrical components of a three phase system?

9. Define critical clearing angle.

10. Write swing equation.

PART B — (5 × 16 = 80 marks)11. (a) (i) With the help of single line diagram, explain the basic components

of a power system. (8)

(ii) Write detailed notes about the per-phase model of a three phase

transformer. (8)

Or

(b) Draw the impedance diagram for the electric power system shown in

figure 11 (b) showing all impedance in per unit on a 100-MVA base.

Choose 20-kV as the voltage base for generator. The three-phase power

and line-line ratings are given below. (16)

G1 : 90 MVA 20 kV X = 9%

T1 : 80 MVA 20/200 kV X = 16%

T2 : 80 MVA 200/20kV X = 20%

G2 : 90 MVA 18 kV X = 9%

Line : 200 kV X = 120

Load : 200 kV, S = 48 MW + j64Mvar

Fig. 11. (b)

12. (a) With neat flow chart explain the computational procedure for load flow

solution using fast decoupled method when the system contains all types

of buses. (16)

Or

(b) Explain the step by step computational procedure for the Gauss-Seidel

method of load flow studies. (16)

13. (a) Explain symmetrical fault analysis using Z-bus matrix with neat flow

chart. (16)

Or

(b) A 11 kV, 100 MVA alternator having a sub-transient reactance of 0.25 pu

is supplying a 50 MVA motor having a sub-transient reactance of 0.2 pu

through a transmission line. The line reactance is 0.05 pu on a base of

100 MVA. The motor is drawing 40 MW at 0.8 p.f. leading with a

terminal voltage of 10.95 kV when a 3-phase fault occurs at the generator

terminals. Calculate the total current in generator and motor under fault

conditions. (16)

14. (a) What are the assumptions to be made in short circuit studies? Deduce

and thaw the sequence network for a line to line fault at the terminals of

an unloaded generator. (16)

Or

(b) Two 11 kV, 20 MVA, three phase, star connected generators operate in

parallel as shown in Figure 14. (b) ; the positive, negative and zero

sequence reactance’s of each being, respectively, j0.l8, j0.15, j0.10 pu. The

star point of one of the generators is isolated and that of the other is

earthed through a 2.0 ohms resistor. A single line to ground fault occurs

at the terminals of one of the generators.

Estimate

(i) the fault current,

(ii) current in grounding resistor, and

(iii) the voltage across grounding resistor. (16)

Fig. 14. (b)

15. (a) Describe the Runge-Kutta method of solution of swing equation for

multi-machine systems. (16)

Or

(b) Derive an expression for the critical clearing angle and clearing time. (16)

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