GATE Electrical Engineering - Complete Master Library

 

📘 Power Systems – Question Bank (Page 10)

🔹 Section A: Conceptual Questions (HVDC)

Q1. What is HVDC transmission?

High Voltage Direct Current transmission used for long-distance bulk power transfer.

Q2. Advantages of HVDC?

• No reactive power loss
• Lower line losses for long distance
• No skin effect
• Better control of power flow

Q3. Main components of HVDC system?

• Rectifier
• Inverter
• Converter Transformer
• Smoothing Reactor
• DC Transmission Line

Q4. When is HVDC preferred?

For long distance (>600 km) and submarine cables.

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🔹 Section B: FACTS Devices

Q5. What are FACTS devices?

Flexible AC Transmission System devices used to control power flow and improve stability.

Q6. Examples of FACTS devices:

• SVC (Static VAR Compensator)
• STATCOM
• TCSC (Thyristor Controlled Series Capacitor)
• UPFC (Unified Power Flow Controller)

Q7. Which FACTS device controls both voltage and power flow?

UPFC

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🔹 Section C: MCQs

Q8. HVDC is economical for:
A) Short distance
B) Medium distance
C) Long distance
D) Distribution system

Answer: C) Long distance

Q9. STATCOM is used for:
A) Frequency control
B) Reactive power control
C) Fault protection
D) Economic dispatch

Answer: B) Reactive power control

Q10. TCSC is connected in:
A) Shunt
B) Series
C) Parallel
D) Ground

Answer: B) Series

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🔹 Section D: Numerical Problems

Q11. A ±500 kV HVDC line carries 2000 A. Find transmitted power.

P = V × I = 500,000 × 2000 = 1000 MW

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Q12. Compare AC and DC losses if AC line has 10% reactive loss and DC has none.

HVDC has lower total losses for long transmission.

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Q13. If SVC injects 50 MVAR, what does it control?

Controls voltage profile.

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🔹 Section E: Quick Revision Points

• HVDC → Best for long distance & underwater cables
• FACTS → Improve stability & power transfer capability
• STATCOM faster than SVC
• UPFC → Most powerful FACTS device

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Page 10 Completed – HVDC & FACTS (Modern Power Systems)