📘 Power Systems – Question Bank (Page 6)
🔹 Section A: Conceptual Questions (Load Flow)
Q1. What is load flow analysis?Load flow analysis determines bus voltages, power flows and line currents under steady state conditions.
Q2. What are the types of buses?- Slack Bus
- PV Bus (Generator Bus)
- PQ Bus (Load Bus)
To balance system losses and provide reference angle.
Q4. Which method converges fastest?Newton–Raphson Method.
Q5. Which method is simplest computationally?Gauss–Seidel Method.
🔹 Section B: MCQs
Q6. Number of slack buses in power system is:A) 0
B) 1
C) 2
D) Depends on system
Answer: B) 1
Q7. In PV bus, which quantities are specified?A) P and Q
B) P and V
C) Q and V
D) V and angle
Answer: B) P and V
Q8. In PQ bus, which quantities are known?A) P and Q
B) V and angle
C) P and V
D) Q and angle
Answer: A) P and Q
Q9. Newton Raphson method is preferred because:A) Simple equations
B) Faster convergence
C) Low memory
D) No iterations
Answer: B) Faster convergence
🔹 Section C: Numerical Problems
Q10. A 2-bus system has slack bus voltage 1∠0 pu. Load at Bus 2 is 1 + j0.5 pu. If line impedance is j0.2 pu, estimate current.Assume V2 ≈ 1 pu Load current I = S* / V = (1 - j0.5) / 1 = 1 - j0.5 pu
Q11. Ybus of a 2-bus system is: Ybus = [ j5 -j5 ] [ -j5 j5 ]
Find self admittance of Bus 1.
Self admittance = j5
Q12. Why Jacobian matrix is used in NR method?
To linearize nonlinear power flow equations.
Q13. If voltage at PQ bus decreases, what happens to reactive power demand?
Reactive power demand increases.
Q14. Advantages of Fast Decoupled Load Flow:
- Less memory requirement
- Faster computation
- Good for large systems
🔹 Section D: Quick Revision Points
- Slack bus → V & angle known
- PV bus → P & V known
- PQ bus → P & Q known
- NR Method → Quadratic convergence
- GS Method → Linear convergence
Page 6 Completed – Load Flow Analysis
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