EX-702-A Power Electronics Applications to Power System - Dec 2024 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aWhat are the objectives of Flexible AC Transmission System (FACTS)? And how the reactive power is controlled in FACTS devices?
   How to answer

   • Define FACTS and its main objectives - power flow control, voltage stability, transient stability, damping oscillations
   • List types of FACTS controllers - series, shunt, combined
   • Explain reactive power control via firing angle, voltage injection, susceptance variation
2. 7 Marks
   bDiscuss the equivalent circuit diagram and working principle of TCSC. What are the merits and demerits of TCSC?
   How to answer

   • Show equivalent circuit of TCSC - fixed capacitor in parallel with TCR
   • Explain working modes - bypass, blocking, capacitive and inductive vernier
   • List merits - increased transfer capability, damping, fast control
   • List demerits - harmonics, resonance risk, cost, complexity
3. 7 Marks
   aDiscuss in detail the basic operating principle of a Unified Power Flow Controller (UPFC).
   How to answer

   • Describe UPFC structure - shunt STATCOM plus series SSSC with common DC link
   • Explain shunt converter control - voltage regulation and DC link
   • Explain series converter control - independent P and Q flow control via injected voltage
4. 7 Marks
   bWhat would be the impact of "Poor Power Quality" on system efficiency, reliability and operation? Why power quality is important?
   How to answer

   • Define poor power quality - sags, harmonics, flicker, transients
   • Explain impact on efficiency - losses, heating, derating
   • Explain impact on reliability and operation - maloperation, outages, equipment damage
   • Justify importance of power quality
5. 7 Marks
   aWhat is the difference between series and shunt compensation? Explain the working of Static Var Compensator (SVC).
   How to answer

   • Differentiate series vs shunt compensation - location, function, voltage vs current control
   • Describe SVC configuration - TCR, TSC, fixed capacitor
   • Explain working - firing angle control of susceptance for voltage regulation
6. 7 Marks
   bWhat do you mean by "Rotor Angle Stability"? How is it enhanced by facts controllers?
   How to answer

   • Define rotor angle stability - ability to remain in synchronism after disturbance
   • Classify small-signal and transient stability
   • Explain FACTS enhancement - power flow control, damping torque, voltage support
7. 14 Marks
   Describe the following :

   1. i)IEEE standards
   2. ii)Harmonic propagation
   3. iii)Control of the converters [Control of the converters Constant Current (CC) and Constant Extinction Angle (CEA)]
   How to answer

   • Summarize IEEE standards relevant to power quality and harmonics
   • Explain harmonic propagation mechanism in network
   • Describe converter control - Constant Current and Constant Extinction Angle principles
8. 7 Marks
   aDistinguish between voltage sag and under voltage. Briefly discuss the techniques used for sag or dip mitigation.
   How to answer

   • Define voltage sag vs undervoltage - magnitude, duration per IEEE
   • Differentiate characteristics and causes
   • List mitigation techniques - DVR, UPS, STATCOM, fast transfer switches
9. 7 Marks
   bExplain the HVDC converters and their characteristics.
   How to answer

   • Describe HVDC converter types - line commutated and voltage source converters
   • Explain rectifier and inverter operation
   • List characteristics - control, harmonics, reactive power requirement
10. 7 Marks
    aExplain the factors to be considered when designing active filters. Also, explain their limitations.
    How to answer

    • List design factors - rating, bandwidth, control strategy, harmonic order, losses
    • Explain shunt vs series vs hybrid active filter considerations
    • Discuss limitations - high cost, complex control, rating limits
11. 7 Marks
    bExplain the dynamic static synchronous series controllers and their application.
    How to answer

    • Define SSSC / dynamic static synchronous series controller concept
    • Explain operation - series voltage injection via VSC
    • List applications - power flow control, oscillation damping, SSR mitigation
12. 7 Marks
    aWhat is the use of filters? Explain the different types of filters used in the transmission and distribution line.
    How to answer

    • Define use of filters - harmonic elimination, power quality improvement
    • Classify passive, active and hybrid filters
    • Explain transmission and distribution applications with examples
13. 7 Marks
    bExplain the design and operation of DSTATCOM for power quality improvement in distribution systems.
    How to answer

    • Describe DSTATCOM structure - shunt VSC with DC capacitor
    • Explain design and control for reactive compensation and harmonic mitigation
    • Explain operation for voltage regulation and power quality improvement
14. 7 Marks
    aWrite a short note on the following terms.

    1. i)Compressed air energy storage system
    2. ii)Super conducting magnet energy storage
    How to answer

    • Describe compressed air energy storage - compression, storage, expansion cycle
    • Describe superconducting magnetic energy storage - coil, cryogenics, power conversion
    • Compare principle, efficiency and applications
15. 7 Marks
    bHow does an energy storage device support the storage and reuse of energy? Discuss the application of energy storage devices.
    How to answer

    • Explain energy storage principle - charging, storing, discharging
    • Describe support to grid - peak shaving, frequency regulation, backup
    • List applications - renewable integration, UPS, FACTS support