Q1. The transient stability of a power system can be improved by:
A) Increasing system voltage
B) Increasing system inertia
C) Using fast excitation systems
D) All of the above
Ans: D
Q2. The swing equation neglects:
A) Damping torque
B) Synchronizing torque
C) Inertia constant
D) Electrical torque
Ans: A
Q3. Equal area criterion is applicable to:
A) One-machine infinite bus system
B) Multi-machine systems
C) Any nonlinear system
D) DC systems only
Ans: A
Q4. The main purpose of automatic voltage regulators (AVR) is to:
A) Control reactive power
B) Control frequency
C) Maintain power factor
D) Control speed
Ans: A
Q5. Reactive power compensation primarily affects:
A) Voltage profile
B) Frequency
C) Real power
D) Load angle
Ans: A
Q6. The inertia constant (H) of a machine represents:
A) Stored kinetic energy per MVA
B) Reactive energy per MVA
C) Rotational losses
D) None
Ans: A
Q7. The synchronizing power coefficient determines:
A) System stability
B) Frequency regulation
C) Rotor speed
D) None
Ans: A
Q8. A high inertia constant improves:
A) Transient stability
B) Voltage stability
C) Reactive power control
D) None
Ans: A
Q9. Damping torque acts to:
A) Reduce oscillations
B) Increase oscillations
C) Reduce frequency
D) Increase speed
Ans: A
Q10. The steady-state stability limit is proportional to:
A)
B)
C)
D) None
Ans: A
Q11. Power system stability is improved by:
A) Fast excitation
B) Series compensation
C) High voltage
D) All
Ans: D
Q12. Voltage instability is mainly due to:
A) Reactive power deficiency
B) Real power deficiency
C) Over-excitation
D) None
Ans: A
Q13. The per-unit inertia constant of a machine depends on:
A) Rating
B) Speed
C) Both
D) None
Ans: C
Q14. For small-signal stability, the system is linearized around:
A) Operating point
B) Origin
C) Maximum load
D) Minimum voltage
Ans: A
Q15. FACTS devices mainly control:
A) Voltage, impedance, phase angle
B) Frequency
C) Rotor speed
D) None
Ans: A
Q16. The SVC (Static VAR Compensator) operates by:
A) Controlling reactive power
B) Controlling real power
C) Frequency control
D) None
Ans: A
Q17. STATCOM differs from SVC in that:
A) It uses voltage source converter
B) It uses thyristor banks
C) It cannot absorb VARs
D) None
Ans: A
Q18. In a power system, reactive power flow causes:
A) Voltage drop
B) Frequency variation
C) Phase lag
D) None
Ans: A
Q19. A shunt capacitor bank provides:
A) Leading VARs
B) Lagging VARs
C) Both
D) None
Ans: A
Q20. Series compensation improves:
A) Transient stability
B) Voltage profile
C) Power transfer capability
D) All
Ans: D
Q21. The equal area criterion is used for:
A) Transient stability
B) Steady-state stability
C) Voltage stability
D) All
Ans: A
Q22. The damping coefficient affects:
A) Speed of oscillation decay
B) Synchronizing torque
C) Frequency
D) None
Ans: A
Q23. Reactive power compensation improves:
A) Power factor
B) Voltage regulation
C) Stability
D) All
Ans: D
Q24. The primary control of voltage is achieved by:
A) Excitation system
B) Governor
C) AVR
D) Both A & C
Ans: D
Q25. The rotor angle stability concerns:
A) Synchronism of generators
B) Voltage balance
C) Frequency match
D) None
Ans: A
Q26. The maximum power transfer occurs when δ =
A) 90°
B) 45°
C) 180°
D) 0°
Ans: A
Q27. In small-signal stability, the oscillation frequency is proportional to:
A) √(Synchronizing torque / Inertia)
B) (Synchronizing torque × Inertia)
C) 1/Inertia
D) None
Ans: A
Q28. The voltage stability margin reduces when:
A) Reactive power demand increases
B) Real power decreases
C) Excitation increases
D) None
Ans: A
Q29. FACTS controllers can be:
A) Series
B) Shunt
C) Combined
D) All
Ans: D
Q30. The purpose of reactive power compensation in transmission line is to:
A) Maintain flat voltage profile
B) Reduce current
C) Improve power transfer
D) All
Ans: D
Q31. The voltage stability limit is reached when:
A) dP/dV = 0
B) dQ/dV = 0
C) dP/dδ = 0
D) dV/dQ = 0
Ans: B
Q32. Reactive power generation in synchronous machines is controlled by:
A) Field current
B) Speed
C) Load torque
D) None
Ans: A
Q33. The main cause of long-term voltage instability is:
A) Slow reactive power support
B) Sudden load increase
C) High frequency
D) High real power
Ans: A
Q34. Static VAR compensators use:
A) Thyristor-controlled reactors (TCR)
B) Thyristor-switched capacitors (TSC)
C) Both
D) None
Ans: C
Q35. The voltage regulation of a line is defined as:
A) % change in voltage from no-load to full-load
B) % loss in power
C) % change in frequency
D) None
Ans: A
Q36. A lagging load requires:
A) Lagging VARs
B) Leading VARs
C) Unity VARs
D) None
Ans: B
Q37. The shunt compensation in transmission line is mainly for:
A) Voltage control
B) Power flow control
C) Frequency control
D) Loss reduction
Ans: A
Q38. Series compensation improves:
A) Power transfer capability
B) Voltage stability
C) Angular stability
D) All
Ans: D
Q39. A STATCOM can supply reactive power:
A) Independently of line voltage
B) Proportional to line voltage
C) Inversely proportional
D) None
Ans: A
Q40. In a power system, reactive power balance is required for:
A) Maintaining bus voltages
B) Maintaining frequency
C) Speed regulation
D) None
Ans: A
Q41. The equal area criterion neglects:
A) Damping
B) Resistance
C) Both
D) None
Ans: C
Q42. The transient stability limit can be increased by:
A) Fast acting exciter
B) Series capacitor
C) HVDC link
D) All
Ans: D
Q43. The load angle δ represents:
A) Phase difference between generator EMF and bus voltage
B) Rotor speed
C) Excitation voltage
D) None
Ans: A
Q44. Fast voltage regulation improves:
A) Transient stability
B) Frequency control
C) Power loss
D) None
Ans: A
Q45. For a given line reactance, maximum power transfer is proportional to:
A)
B)
C)
D)
Ans: A
Q46. In a two-machine system, loss of synchronism means:
A) One machine speeds up while the other slows down
B) Both run at same speed
C) Frequency increases
D) None
Ans: A
Q47. The transient stability limit is higher for:
A) Shorter lines
B) Longer lines
C) High resistance
D) Low reactance
Ans: D
Q48. The governor system controls:
A) Frequency
B) Voltage
C) Power factor
D) None
Ans: A
Q49. Reactive power compensation at load bus helps in:
A) Reducing line current
B) Improving voltage
C) Improving efficiency
D) All
Ans: D
Q50. Voltage instability can be prevented by:
A) Increasing reactive power support
B) Reducing real power
C) Load shedding
D) All
Ans: D
Q51. SSSC (Static Synchronous Series Compensator) controls:
A) Line reactance
B) Shunt voltage
C) Real power
D) Frequency
Ans: A
Q52. UPFC (Unified Power Flow Controller) can control:
A) Voltage
B) Impedance
C) Phase angle
D) All
Ans: D
Q53. The damping torque component of excitation system is improved by:
A) Power system stabilizer
B) AVR gain
C) Speed governor
D) None
Ans: A
Q54. A voltage-controlled bus in load flow is called:
A) PV bus
B) PQ bus
C) Slack bus
D) None
Ans: A
Q55. Reactive power flow between buses depends mainly on:
A) Voltage magnitude difference
B) Phase angle difference
C) Resistance
D) None
Ans: A
Q56. The rotor angle δ increases due to:
A) Acceleration of rotor
B) Deceleration of rotor
C) Reactive power absorption
D) None
Ans: A
Q57. Voltage stability is mainly influenced by:
A) Load characteristics
B) Line impedance
C) Generator excitation
D) All
Ans: D
Q58. Reactive power demand increases with:
A) Inductive load
B) Capacitive load
C) Unity PF load
D) None
Ans: A
Q59. When δ > 90°, the machine:
A) Becomes unstable
B) Stable
C) Overexcited
D) None
Ans: A
Q60. FACTS controllers are used to:
A) Control power flow
B) Improve stability
C) Enhance voltage profile
D) All
Ans: D
Q61. The steady-state stability limit increases with:
A) Increase in excitation
B) Decrease in X
C) Both
D) None
Ans: C
Q62. The equal area criterion uses:
A) Swing curve
B) Power-angle curve
C) PV curve
D) None
Ans: B
Q63. The damping coefficient of system is negative when:
A) Oscillations grow
B) Oscillations decay
C) System is marginally stable
D) None
Ans: A
Q64. In voltage control, reactive power is injected when:
A) Voltage is low
B) Voltage is high
C) Frequency changes
D) None
Ans: A
Q65. Reactive power generation by a synchronous condenser depends on:
A) Excitation
B) Speed
C) Frequency
D) None
Ans: A
Q66. In long lines, reactive power predominates because:
A) High line capacitance
B) Low resistance
C) High inductance
D) All
Ans: D
Q67. Fast-acting AVRs improve:
A) Transient stability
B) Steady-state stability
C) Both
D) None
Ans: C
Q68. Power factor correction reduces:
A) Reactive current
B) Voltage drop
C) Line loss
D) All
Ans: D
Q69. The P-V curve is used for studying:
A) Voltage stability
B) Transient stability
C) Steady-state stability
D) All
Ans: A
Q70. The reactive power balance equation is derived from:
A) Load flow equations
B) Swing equation
C) AVR equations
D) None
Ans: A
Q71. A generator operating at unity power factor delivers:
A) Only real power
B) Only reactive power
C) Both
D) None
Ans: A
Q72. The reactive power support required at receiving end increases with:
A) Line length
B) Load
C) Both
D) None
Ans: C
Q73. The critical clearing angle is determined using:
A) Equal area criterion
B) Load flow
C) Short-circuit analysis
D) None
Ans: A
Q74. FACTS devices use:
A) Power electronics
B) Transformers
C) Induction coils
D) None
Ans: A
Q75. The frequency of power oscillations depends on:
A) Inertia and synchronizing torque
B) Damping
C) Excitation
D) None
Ans: A
Q76. The reactive power requirement of an inductive load is:
A) Positive
B) Negative
C) Zero
D) None
Ans: A
Q77. Voltage stability analysis is done using:
A) Load flow programs
B) Transient stability tools
C) Frequency response
D) None
Ans: A
Q78. A voltage dip indicates:
A) Reactive power shortage
B) Real power shortage
C) Frequency drop
D) None
Ans: A
Q79. For transient stability improvement, which is most effective?
A) Series capacitor
B) Shunt capacitor
C) Reactor
D) Load shedding
Ans: A
Q80. A low short-circuit ratio (SCR) indicates:
A) Weak grid
B) Strong grid
C) Stable system
D) None
Ans: A
Q81. Reactive power can be supplied by:
A) Synchronous condensers
B) Capacitor banks
C) FACTS devices
D) All
Ans: D
Q82. The voltage drop across an inductive line is due to:
A) Reactive power flow
B) Resistive power flow
C) Corona loss
D) None
Ans: A
Q83. In a long transmission line, Ferranti effect occurs due to:
A) Shunt capacitance
B) Series inductance
C) Corona
D) None
Ans: A
Q84. The steady-state power transfer is maximum at δ =
A) 90°
B) 45°
C) 30°
D) 180°
Ans: A
Q85. FACTS controllers are mainly classified based on:
A) Connection type
B) Converter type
C) Function
D) All
Ans: D
Q86. Voltage collapse in heavily loaded system is due to:
A) Lack of reactive power support
B) Frequency instability
C) Real power excess
D) None
Ans: A
Q87. A synchronous condenser improves:
A) Voltage stability
B) Power factor
C) Reactive support
D) All
Ans: D
Q88. Reactive power flow direction indicates:
A) Lagging/leading condition
B) Load type
C) Source condition
D) All
Ans: D
Q89. Power system stabilizer (PSS) adds:
A) Damping torque
B) Synchronizing torque
C) Both
D) None
Ans: A
Q90. The purpose of excitation control is to:
A) Maintain voltage
B) Provide damping
C) Control reactive power
D) All
Ans: D
Q91. The reactive power of transmission line increases with:
A) Square of voltage
B) Square of current
C) Both
D) None
Ans: A
Q92. Series capacitor in line compensates:
A) Line reactance
B) Resistance
C) Capacitance
D) None
Ans: A
Q93. The short-term voltage stability time frame is:
A) 0–10 sec
B) 10–60 sec
C) Minutes
D) Hours
Ans: A
Q94. Reactive power deficiency leads to:
A) Low voltage
B) High voltage
C) High current
D) Both A & C
Ans: D
Q95. Shunt reactor is used to:
A) Absorb reactive power
B) Generate reactive power
C) Control frequency
D) None
Ans: A
Q96. Reactive power flows from:
A) Leading to lagging bus
B) Lagging to leading bus
C) High voltage to low voltage
D) None
Ans: A
Q97. The frequency stability relates to:
A) Balance between generation and load
B) Reactive power balance
C) Voltage control
D) None
Ans: A
Q98. Voltage control in distribution systems is mainly done by:
A) OLTC transformers
B) Capacitor banks
C) Voltage regulators
D) All
Ans: D
Q99. In load flow analysis, reactive power limits are applied to:
A) Generator buses
B) Slack bus
C) Load buses
D) None
Ans: A
Q100. Reactive power compensation improves:
A) Transmission efficiency
B) Voltage profile
C) Stability margin
D) All
Ans: D
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