Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Winter 5th Sem Old 150902 Power System Analysis And Simulation Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?V (Old) EXAMINATION ? WINTER 2019
Subject Code: 150902 Date: 06/12/2019
Subject Name: Power System Analysis And Simulation
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1 (a) Derive equivalent- ? circuit of a long transmission line. 07
(b) A three phase, 60 Hz transmission line, 130 Km long delivering 270 MVA at 325
kV & a 0.8 p.f. lagging. The resistance & inductance of the lines per phase per km
are 0.036 ? & 0.8 mH respectively, While capacitance is 0.0112 ?F / km / phase.
Using Nominal-T method.
Calculate:
(1) Sending end Voltage (2) Sending end Current (3) Voltage regulation and
(4) Line efficiency.
07
Q.2 (a) Write a brief note on selection of circuit breakers. 07
(b) Explain in brief transients in RL series circuits 07
OR
(b) Draw the reactance diagram & mark all reactance in per unit. Choose 12.2 kV as a
base for generator & 50 MVA.
07
Q.3 (a) Derive the necessary equations to convert: (i) phase quantities into symmetrical
components (ii) symmetrical components in to phase quantities.
07
(b) Figure shows a system having four synchronous generators each rated 11.2 kV, 60
MVA and each having a subtransient reactance of 16%. Find (a) fault level for a
fault on one of the feeders (near the bus with XR = 0). (b) The reactance of the
current limiting reactor XR to limit the fault level to 860 MVA for a fault on one of
the feeders near the bus.
07
OR
Q.3 (a) Prove that zero impedance of fully transposed transmission lines is always higher
than positive and negative sequence impedances.
07
(b) The System shown in Fig. is delivering 50 MVA at 11 kV, 0.8 lagging power factor
into a bus which may be regarded as infinite.
07
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Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?V (Old) EXAMINATION ? WINTER 2019
Subject Code: 150902 Date: 06/12/2019
Subject Name: Power System Analysis And Simulation
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1 (a) Derive equivalent- ? circuit of a long transmission line. 07
(b) A three phase, 60 Hz transmission line, 130 Km long delivering 270 MVA at 325
kV & a 0.8 p.f. lagging. The resistance & inductance of the lines per phase per km
are 0.036 ? & 0.8 mH respectively, While capacitance is 0.0112 ?F / km / phase.
Using Nominal-T method.
Calculate:
(1) Sending end Voltage (2) Sending end Current (3) Voltage regulation and
(4) Line efficiency.
07
Q.2 (a) Write a brief note on selection of circuit breakers. 07
(b) Explain in brief transients in RL series circuits 07
OR
(b) Draw the reactance diagram & mark all reactance in per unit. Choose 12.2 kV as a
base for generator & 50 MVA.
07
Q.3 (a) Derive the necessary equations to convert: (i) phase quantities into symmetrical
components (ii) symmetrical components in to phase quantities.
07
(b) Figure shows a system having four synchronous generators each rated 11.2 kV, 60
MVA and each having a subtransient reactance of 16%. Find (a) fault level for a
fault on one of the feeders (near the bus with XR = 0). (b) The reactance of the
current limiting reactor XR to limit the fault level to 860 MVA for a fault on one of
the feeders near the bus.
07
OR
Q.3 (a) Prove that zero impedance of fully transposed transmission lines is always higher
than positive and negative sequence impedances.
07
(b) The System shown in Fig. is delivering 50 MVA at 11 kV, 0.8 lagging power factor
into a bus which may be regarded as infinite.
07
2
Generator: 60 MVA, 12 kV, X? d=35%
Transformer (each): 80 MVA, 12/66 kV, X=8%
Line: X=12 ?
Calculate the symmetrical current that the circuit breaker A and B will be called
upon to interrupt in the event of a three phase fault occurring at F near the circuit
breaker B.
Q.4 (a) Explain line to ground fault on an unloaded generator using symmetrical
components.
07
(b) A 25 MVA, 11 kV generator has X1 = 0.2 p.u., X2 = 0.3 p.u. and X0 = 0.1 p.u..
The neutral of the generator is solidly grounded. Determine the sub-transient
current in the generator and the line-to-line voltages for sub-transient condition
when a Y-B fault occurs at the generator terminals. Assume pre-fault currents and
fault-resistance to be zero.
07
OR
Q.4 (a) Derive an expression for fault current for double line-to-ground fault by
symmetrical components method.
07
(b) A three phase, 37.5 MVA, 33 kV alternator having X1 = 0.18 pu, X2 = 0.12 pu and
X0 = 0.10 pu, based on its ratings, is connected to a 33 kV overhead line having X1
= 6.3 ohms, X2 = 6.3 ohms and X0 = 12.6 ohms per phase. A single line to ground
fault occurs at the remote end of the line. The alternator neutral is solidly grounded.
Calculate fault current.
07
Q.5 (a) Explain the need of neutral grounding of system. Describe any one method of
neutral grounding.
07
(b) A grid line operating at 132 kV consists of 2 cm diameter conductors spaced 4
meters apart. Determine the disruptive critical voltage and visual corona voltage
for the following data: Temperature 44?C, barometric Pressure 73.7 cm of
mercury, conductor surface factor 0.84, fine weather 0.8 and rough weather 0.66.
07
OR
Q.5 (a) Briefly discuss the factors affecting Corona. 07
(b) Explain the phenomena of arcing grounds. How does neutral grounding eliminate
the arcing ground?
07
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This post was last modified on 20 February 2020