Amie electrical engineering power system performance winter 2017 question paper

Amie electrical engineering winter 2017 question paper power system performance.

Iei winter 2017 power system performance question paper.

Ieindia winter 2017 power system performance question paper.

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Question paper

W17:2 FN 414 (1472)
Time Three hours
Micimum Micros: 200
ver questions, aking ANY TWO from Group A,
го Grap B and Arom Group с.
il parts of a question 4 h etc. should be
amanvered at one place.
enver should be and the point and be supple
mented with rear sketches unnecessary long answer may

Any missing or wrong distuu be assumed suitably
getting proper justification
Figures on the right-hand side margin indicate full marks

Group A
Discuss the need to express electrical quantities in
per unit system. Explain how are the importances in
DIL are converted in one systems of buses (MVA old system) to new system (MVA new, kV new).
Compute the pe values for a given power system
Generator Gl:20 MINA 6.6KV, Xel=0.t pi
Transformer. Tn;8 MVA, 66kV/132kV, XG
0.08 pu
Transmission line LLV=1324V, impedance is
Assume the MVA base is 50, compute the new pu

EL 42

impedance values for the above mentioned compo
(c) A three phase, 20 MVA, 10kV alternator has inter
nal reactance of 5% with negligible resistance. Find
the external reactance to be connected in series with
the alternator so that the steady state current on
short circuit does not exceed 8 times the full load
current value.
2. (a) Explain the need for symmetrical component trans
formation for three phase voltages and currents.
(6) Consider a L-L fault on phases and c through a
fault impedance Zf. Calculate the expression for
fault current
(e) A three phase, four wire system has three phase
currents (RYB) as Ir= 230°, ly = 502300°
and b= 30Z180°, find the positive, negative and
zero sequence current components along with the
current in the neutral wire.
3. (a) For a 4 bus system having line reactances (and
negligible line resistances) mentioned in the Table-1,
draw the power system network and compute
S. No.
Bus (from-to) Reactance
1-3 0.15j
14 0.1)
1-2 0.2j
2-3 0.1j
24 0.15j
(0) Formulate the load flow problem and discuss how
Ybus matrix Table-I
the voltage at the oth bus is iteratively calculated
using Gauss-Siedel Method.
v7:2N: EL. 414 (1472) (Continued)

(e) Explain the effect of acceleration factor on conver
gence of G-S method.
4. (a) Incremental fuel costs Rs/MWh for a plant com
prising two units is given as:
(df,lar..) -0.008P, +8 and
(af, dr. 0.0096P,+ 6.4.
Determine the saving in fuel cost in Rs/hr for the
economic distribution of load of 900 MW between
two units of plant when unit 1 delivers 400 MW and
unit 2 delivers 500 MW. Compare this with the equal
distribution of the same total load)
(6) For a plant with three generating units with outputs
Pg1, Pg2 and Pg3 and penalty factors L1, L2 and
L3 indicate how the load should be economically
distributed among these units. Derive a suitable
expression for the same.
(C) Explain briefly:
(1) Plot of input output curve for a generating unit
showing fuel input vs power output.
(ii) Penalty factor for ith plant and list the various
factors it depends on.
Group B
5. (a) Discuss the block diagram representation of
HVDC system and list the components used.
(b) Show how power flow through HVDC system can
sion for the same.
be effectively controlled. Derive a suitable express

w17:2 FN: EL 414 (1472)


(Turn Over)

to generators are rated 200 MW and 400 MW
une operating in parallel. The droop character
Neces of the governors are 4% and 3% respec
vey from no load to full load. Assuming that the
generator are operating at 50Hz at no load condi
is calculate how a load of 500 MW would be
shared between them. Calculate the system
tiequency for this loud
Determine the time of operation of a 5A, 3 sec
overcurrent relay having a current setting of 125%
supply circuit through a 400/5 Ct when the circuit
anda time setting multiplier of 0.8 connected to
curries a fault current of 4KA. Use the time vs PSM
characteristics of the relay from Table-ll below:
Tre 58 4.4 3.5 3 2.7 2.5 2.3
PSM 2 6 8 10 12 14 16

Daw and discuss the characteristics of reactance,

Discuss the distance protection scheme for trans
mission lines
1. Explain the Swing equation. Discuss a suitable
method for its solution
(2) Explain using suitable diagram equal area criteria
for power system stability.
(0) Asynchronous machine is connected to an infinite
bus through a double circuit line. A fault occurs at
the middle of one of the double circuit line. Draw
the power angle curves for the generator for pre
fint, during fault and post fault conditions and
comment on the system stability.

wn:2BN: EL (1472)


Write short notes on:

a pilot wire protection
b primary and backup protection.
c arcing faults.
9. We short notes on the following
1 Single line representation of powers system
2 Unsymmetrical faults
3 Back back HVDC systems
4 Automatic voltage regulator
5 Differential protection.
6 relay coordination
7 Calculation of circuit  breaker capacity
8 Transient stability
9 Three Zone protection
10  Different types of HVDC link.