CONFIDENTIAL
EE/MAY 2021/EPO520
UNIVERSITI TEKNOLOGI MARA
TEST 1
COURSE
:
POWER SYSTEM 1
COURSE CODE
:
EPO520
DATE
:
MAY 2021
TIME
:
2 HOURS
INSTRUCTIONS TO CANDIDATES
1.
This question paper consists of TWO (2) questions. Answer ALL the questions. Show your work
CLEARLY on a paper with your handwriting. Start each answer on a new page.
2.
This is an individual test; you are not permitted to work with another student, copy any portion
of another student's work, or share your work with another student. Maintain your integrity.
You should convert and combine all of your answer papers into a single PDF file and submitted
ONLINE. File must be named as: YOUR FULL NAME (YOUR UiTM NO).
3.
FILL IN THE FOLLOWING PARTICULARS
NAME
: ___________________________________________________________________
UiTM ID : ___________________________________________________________________
GROUP : ___________________________________________________________________
LECTURER
: ___________________________________________________________________
PROGRAMME CODE
QUESTION
COGNITIVE
LEVEL
CO
PO
Q1a
C3
CO1
PO1
/5
Q1b
C4
CO2
PO2
/15
© Hak Cipta Universiti Teknologi MARA
MARKS
CONFIDENTIAL
CONFIDENTIAL
EE/MAY 2021/EPO520
Q2a
C3
CO1
PO1
/5
Q2b
C4
CO2
PO2
/15
TOTAL
/40
DO NOT TURN THIS PAGE UNTIL YOU ARE TOLD TO DO SO
This test paper consists of 4 printed pages
© Hak Cipta Universiti Teknologi MARA
CONFIDENTIAL
CONFIDENTIAL
EE/MAY 2021/EPO520
Q1a. A 132 kV line is fed through an 11/132 kV transformer from a constant 11 kV
supply as shown in Figure 1. At the load end of the line the voltage is reduced by
another transformer of nominal ratio 132/11 kV. The total impedance of the line and
transformers at 132 kV is (25+j66) Ω. Both transformers are equipped with tapchanging facilities which are arranged so that the product of the two off-nominal
settings is unity. If the load on the system is 100MW at 0.9 p.f. lagging, calculate the
settings of the tap-changers required to maintain the voltage of the load busbar at 10.5
kV.
(5 marks)
Figure 1
Q1b. A 100 MVA, 10.5 kV, 50 Hz synchronous generator has a synchronous
reactance of 15Ω per phase and negligible resistance. The generator is delivering
rated power of 0.95 p.f lagging at the rated terminal voltage to an infinite bus.
a) Compute the excitation voltage per phase, Eg and the power angle, δ.
(5 Mark)
b) If the excitation voltage is maintained at the value calculated in (a), the driving torque
is reduced accordingly until the generator is delivering 50 MW. Determine the new
armature current and the power factor.
(5 Marks)
c) If the generator is operating at the same excitation voltage of part (a), what is the
steady-state power the machine can deliver before losing synchronism?
(5 Marks)
Q2a. A 275 kV, 50 Hz, three-phase transmission line is 40 km long. The resistance
per phase is 0.15 Ω/km and the inductance per phase is 1.3263 mH/km. The line is
supplying a three-phase load of 200 MVA at 0.85 power factor lagging at 275 kV. Use
the short line model to find the voltage regulation and line efficiency.
(5 Marks)
© Hak Cipta Universiti Teknologi MARA
CONFIDENTIAL
CONFIDENTIAL
EE/MAY 2021/EPO520
Q2b. A 345 kV, 50 Hz, three-phase transmission line is delivering 500 MVA at 0.8
lagging power factor with the receiving-end voltage of 345 kV. The transmission line
is 300 km long. The inductance for each phase is 0.97 mH/km and the shunt
capacitance for each phase is 0.012 μF/km. By assuming a lossless transmission line,
a) Determine the phase constant (β), wavelength (λ), transmission
impedance (Zc) and surge impedance loading (SIL).
line surge
(5 Marks)
b) Determine the ABCD parameters of transmission line
(5 Marks)
c) Determine the sending-end quantities.
(5 Marks)
d) Determine the voltage regulation (%VR) and line efficiency (%η).
(5 Marks)
e) Determine the size of shunt capacitors in farads to be installed at the receivingend to keep the receiving-end voltage at 345 kV when the line is energized with 345
kV at the sending end.
(5 Marks)
© Hak Cipta Universiti Teknologi MARA
CONFIDENTIAL