Power System Engineering-II SPPU Endsem Question Paper May 2023

Questions

1. Q1

   1. a)

      Give the detailed classification of buses used in load flow analysis.

      Also asked:Nov 2024

      [6]
   2. b)

      State the following statements are true or false with justification. i) The bus admittance matrix is a sparse matrix ii) In fast decoupled load flow, the resistance of the lines are neglected.

      [6]
   3. c)

      Impedances (in pu) between buses are given in the following Fig. Calculate the Ybus of the system.

      [6]
   OR

2. Q2

   1. a)

      Draw the per-unit impedance diagram of the system shown below. Take the base values as 10MVA, 33kV on the load. 2

      [6]
   2. b)

      Explain load flow analysis using the fast decoupled method.

      [6]
   3. c)

      What is per unit system? State the advantages and disadvantages.

      Also asked:May 2024

      [6]

3. Q3

   1. a)

      For the power system shown in the figure below, the specifications of the components are the following: G1 : 25kV, 100 MVA, X=9% G2: 25kV, 100 MVA, X=9% T1 : 25kV/220 KV, 90 MVA, X=9% T2: 220 kV/25kV, 90MVA, X=9% Line 1:X=150 ohms If the three-phase fault is taken place at bus 1, calculate fault current supplied by each generator. Take generator 1 rating as base values.

      [12]
   2. b)

      Draw the nature of fault current, if the symmetrical fault is taken place at the terminal of an unloaded alternator. Clearly mark the sub-transient, transient and steady state period.

      [6]
   OR

4. Q4

   1. a)

      Find the fault current, if three phase fault is taken place at (i) F1 and (ii)F2.

      [12]
   2. b)

      Write a short note on “Feeder reactor”. 3

      [6]

5. Q5

   1. a)

      This part has equations that don’t show as text. Open the PDF to read it.

      [6]
   2. b)

      Draw a zero-sequence diagram for the following transformer connection. i) Delta-star transformer (With isolated neutral) ii) Delta-star connected transformer with neutral grounded with impedance.

      Also asked:Nov 2025 ·May 2025 ·Nov 2023

      [6]
   3. c)

      This part has equations that don’t show as text. Open the PDF to read it.

      [6]
   OR

6. Q6

   1. a)

      Derive the equation for fault current in LLG fault.

      Also asked:Nov 2025 ·May 2025 ·Nov 2024 ·May 2024

      [9]
   2. b)

      A20-MVA, 6.6-kV, 3-Phase alternator is connected to a 3-Phase transmission line. The per unit positive, negative and zero-sequence impedances of the alternator are j0,1,j0.05 and j0.04 respectively. The neutral of the alternator is connected to the ground through an inductive reactor of j0.05 p.u. The per unit positive, negative and zero-sequence impedances of the transmission line are j0.2, j0.2 and j0.3, respectively. Per-unit values are based on the machine ratings. A solid ground fault occurs at one phase of the far end of the transmission line. Calculate the fault current.

      [9]

7. Q7

   1. a)

      Compare HVDC and EHVAC transmission systems.

      Also asked:Nov 2024 ·May 2024

      [6]
   2. b)

      Draw the complete single-line diagram of the HVDC system showing all components.

      Also asked:Nov 2024 ·May 2024 ·Nov 2023

      [5]
   3. c)

      Write a short note “Monopolar HVDC station”.

      [5]
   OR

8. Q8

   1. a)

      Explain “Constant Extinction Angle control in HVDC systems”

      Also asked:May 2025

      [6]
   2. b)

      Write the functions of the following components in HVDC system: i) AC side filters. ii) Converter transformer.

      [5]
   3. c)

      This part has equations that don’t show as text. Open the PDF to read it.

      [5]