Monday, 23 February 2026

📘 Power Systems – Question Bank (Page 9)

🔹 Section A: Conceptual Questions (Operation & Control)

Q1. What is power system control?

Maintaining system frequency and voltage within acceptable limits.

Q2. What are main control loops?

Q3. What is load frequency control?

LFC maintains system frequency by adjusting generator output.

Q4. Why frequency drops when load increases?

Mechanical input < Electrical output → Rotor slows down → Frequency drops.

Q5. What is droop characteristic?

Relationship between frequency deviation and power output change.

Q6. Nominal frequency in India is:
A) 60 Hz
B) 55 Hz
C) 50 Hz
D) 45 Hz

Answer: C) 50 Hz

Q7. Primary control in power system is provided by:
A) Governor
B) Exciter
C) Relay
D) Transformer

Answer: A) Governor

Q8. AVR controls:
A) Frequency
B) Voltage
C) Current
D) Power factor only

Answer: B) Voltage

Q9. If load increases suddenly, frequency:
A) Increases
B) Decreases
C) Remains constant
D) Doubles

Answer: B) Decreases

Q10. A 1000 MW system has frequency sensitivity 2% load change per 1% frequency change. If load increases by 1%, find frequency deviation.

Given 2% load ↔ 1% frequency 1% load ↔ 0.5% frequency For 50 Hz system: Frequency deviation = 0.5% of 50 = 0.25 Hz New frequency ≈ 49.75 Hz

Q11. If speed regulation is 5%, what does it indicate?

Full load frequency drop = 5% from no-load frequency.

Q12. Generator voltage rises. Which system corrects it?

Automatic Voltage Regulator (AVR).

Q13. Tie-line power depends on:

Angle difference between areas.

Page 9 Completed – Operation & Control (LFC + AVR)