EX-702-A Power Electronics Applications to Power System - Nov 2023 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 is the Flexible AC Transmission Systems (FACTS) controller? Explain different types of FACTS controllers.
   How to answer

   • Define FACTS controller and its need for AC transmission control
   • Classify into series, shunt, combined series-series and combined series-shunt types
   • List examples: SVC, STATCOM, TCSC, SSSC, UPFC, IPFC
   • State function of each type in power flow and voltage control
2. 7 Marks
   bExplain the working of UPFC (Unified Power Flow Controller) with necessary circuit diagram.
   How to answer

   • Show UPFC schematic with series and shunt VSC with common DC link
   • Explain shunt converter for voltage and reactive power control
   • Explain series converter for voltage injection and power flow control
   • Summarize independent P-Q control capability
3. 7 Marks
   aGive the comparison of active and passive filters.
   How to answer

   • Define active filter using power electronic converter
   • Define passive filter using L-C components
   • Compare on basis of size, cost, tuning, harmonics compensation
   • Conclude suitability for dynamic vs fixed compensation
4. 7 Marks
   bWhat should be the standards of power quality in power system?
   How to answer

   • Define power quality and need for standards
   • List parameters: voltage, frequency, harmonics, flicker, interruptions
   • Mention standards like IEEE-519, IEC-61000, limits for THD, sag/swell
   • State acceptable limits for utility and consumer
5. 7 Marks
   aExplain following terms: voltage sag and swell and series resonance.
   How to answer

   • Define voltage sag: short duration voltage drop, causes
   • Define voltage swell: short duration voltage rise, causes
   • Define series resonance: resonance in series L-C circuit
   • Mention effects on power system equipment
6. 7 Marks
   bWhat do you understand by power system reliability? Also state its enhancement by using FACTs controllers in multi machine system.
   How to answer

   • Define power system reliability indices
   • Explain need for reliability in multi-machine system
   • Explain role of FACTS in damping oscillations and voltage support
   • State enhancement in transient stability and loadability
7. 14 Marks
   What is a static VAR compensator? Explain its design, operation and characteristic.
   How to answer

   • Define SVC/Static VAR compensator and its purpose
   • Describe design: TCR, TSC, fixed capacitor combination
   • Explain operation in inductive and capacitive modes
   • Draw V-I characteristic and state voltage regulation
8. 7 Marks
   aDefine these terms: static phase shifter and super capacitors.
   How to answer

   • Define static phase shifter for phase angle control
   • Explain thyristor controlled phase shifting principle
   • Define supercapacitor and its energy storage principle
   • State applications in power system
9. 7 Marks
   bWhat is the fundamental principle of operation of controlling harmonics? Explain in detail.
   How to answer

   • State principle of harmonic detection and cancellation
   • Explain use of active filter injecting equal opposite harmonics
   • Describe control: p-q theory, synchronous reference frame
   • Explain filtering for THD reduction
10. 14 Marks
    What are the causes and adverse effects of harmonics on power system? Explain.
    How to answer

    • List harmonic sources: non-linear loads, converters, arc furnaces
    • Explain distortion of voltage and current waveforms
    • List adverse effects: heating, resonance, protection maloperation
    • Mention increased losses and equipment derating
11. 7 Marks
    aWhat do you understand by STATCON? Explain in detail about its working.
    How to answer

    • Define STATCON/STATCOM as shunt VSC based compensator
    • Describe structure: VSC, DC capacitor, coupling transformer
    • Explain working in capacitive and inductive modes
    • State advantages over SVC
12. 7 Marks
    bDescribe in detail about structure of power storage devices.
    How to answer

    • Classify storage devices: battery, SMES, flywheel, supercapacitor
    • Describe construction of each type
    • Explain energy conversion principle
    • Compare capacity and response time
13. 7 Marks
    aExplain the working of pump storage hydro electric power plant.
    How to answer

    • Define pumped storage plant with upper and lower reservoirs
    • Explain pumping mode during off-peak and generation during peak
    • Describe reversible pump-turbine and motor-generator set
    • State role in load balancing and grid stability
14. 7 Marks
    bHow does an energy storage device help to store and reuse energy? Explain the application of energy storage devices.
    How to answer

    • Explain charging and discharging of storage device
    • Describe energy conversion and reuse mechanism
    • List applications: peak shaving, UPS, renewable integration
    • State benefits for reliability and power quality