Exam Regular/Back
TRIBHUVAN UNIVERSITY Level M.Sc. Full Marks 60
Pulchowk Campus Programme MSP, MSDG Pass Marks 30
Examination Control Division Year/Part I/ I Time 3 hr.
2079 Jeshtha
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Subject: Digital Simulation and Analysis of Power Systems
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Attempt all questions.
Figures in the margins indicate Full Marks.
Assume suitable data if necessary.
Answer in your own words as far as practicable.
1. List down and briefly explain the requirements to be met by a properly designed and operated power system.
[5]
2. Find the bus admittance matrix for the following network: [6]
Transformation ratios of the transformers are forT1: t:1 and for T2: 1:1.
Neglect the shunt admittances in the network.
3. Obtain the power flow solution by fast decoupled method for the given network up to three iterations.
Impedances are given in per unit on 100MVA base. Assume flat voltage start. [8]
4. How is LU decomposition carried out? Explain step-by-step. [5]
5. Compare among three loadflow methods: GSLF, NRLF and FDLF. List out the areas of their applications with
proper reasoning. (5)
6. For a 4 bus network with the following line data, obtain Zbus matrix by step by step Zbus building . (9)
Line 1-2 1-3 2-3 2-4 1-4 0-1 0-2
Series reactance, pu j0.1 j0.08 j0.125 J0.12 j0.075 j0.0825 j0.1
7. For a DL fault at bus 5 of the system shown below with Zf=j0.05pu, determine the fault currents flowing through
the faulted point. Further, determine the branch currents and bus voltages during the fault. (9)
For generators G1 and G2,
X1 = X2=0.2 pu, X0=0.05pu
For transmission line L1, L2
and L3, X1 = X2=0.1 pu,
X0=0.3pu
For transformers T1 and T2, X1 = X2=X0=Xl= 0.05pu
Bus impedance matrices for positive, negative and zero sequence networks for the above system are given
below.
Negative sequence bus admittance matrix is same as the positive sequence matrix.
8. What is the significance of power system security assessment? Explain the major components of power system
security assessment. [2+4]
9. Why are the numerical integration techniques required while solving transient stability problems? Discuss briefly
about the application of modified Euler’s method for solving power system stability studies. [2+5]
