Ch:-1
Current and Voltage Relations on a
Transmission Line:
1. From first principles, derive the A, B, C
and D constants of a long transmission line.
2. Derive the equation for active and reactive
powers flow in transmitted to load over a long line.
3.
Starting from the first principles, show
that surges behave as travelling waves. Find expressions for surge impedance and wave velocity.
4.
What is importance of receiving end
power circle diagram? Explain the steps
of constructing it.
5.
Derive expressions of voltage phasor and
current phasor at any point of a long transmission line as function of distance
x from receiving end in terms of distributed parameters of the
line, voltage phasor VR (voltage at receiving end) and current phasor IR
(current at receiving end). State difference between characteristic impedance
and surge impedance of the line.
6.
What
is an equivalent π and equivalent T circuit of a long transmission line?
7.
Derive the ABCD constants for medium
transmission line using Nominal Π representation. Also write the expressions
for voltage regulation and efficiency for the same line.
Ch:-2
System Modeling:
8.
What is importance of one line diagram
of a power system? How it is drawn?
9. Explain one-line diagram in brief. What is
P. U. system? Write advantages of per unit system.
10.
Explain the Equivalent Circuit model of
Synchronous machine. From the first principal, derive Vt = Ef – Ia (Ra+ jXs)
Where Xs = Xar + Xl. Also draw the equivalent circuit diagram.
11.
With the help of neat phasor diagram,
explain the operation of synchronous generator for different field excitation.
Ch:-3
Symmetrical Three-Phase Faults:
12. Draw the waveforms for fault current for a
3-phase fault on alternator
terminals. Explain the
sub-transient, transient and steady state reactance. What is their significance
in fault calculations?
13. Explain the importance of bus impedance
matrix in fault calculation.
14. How the circuit breaker is selected for
any particular location.
Ch:-4
Symmetrical Components:.
15.
Write a brief note on phase shift of
symmetrical components in Y-Δ transformer banks.
16. Write a note on zero sequence networks in
brief.
17.
Derive the expressions of positive,
negative and zero sequence voltage components in terms of given set of
unbalance voltage phasors Va, Vb and Vc. Also prove that the transformation
used is power invariant.
Ch:-5
Unsymmetrical Faults:
18. Using appropriate interconnection of
sequence networks, derive the equation for a line to line fault in a power system with a fault impedance of f Z
19. Justify the following statement:
“For a fault at alternator terminals, a
single line to ground fault is generally more severe than a 3-ph fault whereas
for faults on transmission lines, a 3-ph fault is more severe than other
faults.”
20. Explain how fault current can be calculated when L-G fault occur through a fault
impedance Zf.
21.
Draw
a general circuit which can be used to determine zero sequence network of a
two-winding transformer. Using this circuit, draw the zero sequence networks
for (i) delta-star transformer with star point grounded. (ii) delta-delta
transformer. (iii) star-star transformer with star point grounded.
22.
Derive
an expression for the fault current for a double-line
fault as an unloaded generator.
Ch:-6
Corona:
23.
Describe the phenomena of corona in brief.
What are the factors and conditions affecting corona loss?
24. Explain the advantage, disadvantage and
method of reducing phenomena of corona.
Ch:-7
Neutral Grounding:
25. What are the various methods of neutral
grounding? Explain all. (resonant grounding)
26. Explain neutral grounding using phasor
diagrams.. Give Advantage of neutral grounding.
Ch:-8
Transients in Power Systems:
27. Explain single and double frequency
transient.
28. Write a brief note on capacitance
switching.
29. Discuss the behavior of
a travelling wave when it reaches the end of (i) open circuited (ii)short
circuited transmission line. Draw diagrams to show voltage and current on the
line before and after the wave reaches at the end.
Combination
30.
Give reasons for following:
1.
The
analysis of unsymmetrical faults can be more easily done with the help of
symmetrical components than by a direct solution of the unbalanced circuit.
2. A travelling wave suffers reflection when it
reaches discontinuity.
3. The
disruptive critical voltage is less than visual critical voltage.
