Q51. In a power system, the main control objective of a FACTS device is:
A) Rapid control of voltage and power flow
B) Change of frequency
C) Generator speed control
D) None
Ans: A
Q52. The series FACTS controller mainly controls:
A) Line current and power flow
B) Bus voltage
C) Reactive compensation only
D) None
Ans: A
Q53. The shunt FACTS controller mainly controls:
A) Bus voltage and reactive power
B) Real power
C) Frequency
D) None
Ans: A
Q54. SSSC (Static Synchronous Series Compensator) injects:
A) Controllable series voltage
B) Controllable shunt current
C) Reactive current
D) None
Ans: A
Q55. The control variable in a STATCOM is:
A) Reactive current
B) Line resistance
C) Frequency
D) None
Ans: A
Q56. The main advantage of STATCOM over SVC:
A) Better voltage control at low voltages
B) Lower cost
C) Slower response
D) None
Ans: A
Q57. The reactive power capability of STATCOM is:
A) Constant current characteristic
B) Constant impedance
C) Constant voltage
D) None
Ans: A
Q58. A TCSC controls power flow by:
A) Changing line reactance
B) Adjusting voltage magnitude
C) Changing phase angle
D) None
Ans: A
Q59. In TCSC, when firing angle increases:
A) Effective reactance increases
B) Effective reactance decreases
C) Power increases
D) None
Ans: A
Q60. The TCSC operates in:
A) Capacitive or inductive mode
B) Resistive mode
C) Neutral mode
D) None
Ans: A
Q61. The damping of power oscillations by TCSC is achieved by:
A) Modulation of reactance
B) Firing angle control
C) Both
D) None
Ans: C
Q62. The control input of a STATCOM is typically:
A) DC link voltage reference
B) Phase angle
C) Line current
D) None
Ans: A
Q63. The energy storage element in STATCOM is:
A) DC capacitor
B) Inductor
C) Transformer
D) None
Ans: A
Q64. The STATCOM injects reactive current in:
A) Quadrature with bus voltage
B) In phase
C) Anti-phase
D) None
Ans: A
Q65. The UPFC’s main feature is:
A) Simultaneous control of P and Q
B) Only voltage
C) Only power angle
D) None
Ans: A
Q66. The UPFC consists of:
A) Two VSCs connected back-to-back via DC link
B) One converter
C) Thyristor bridge
D) None
Ans: A
Q67. The real power exchange between two converters in UPFC is via:
A) Common DC link
B) AC tie line
C) Transformer
D) None
Ans: A
Q68. The reactive power in UPFC can be independently controlled at:
A) Both ends of the line
B) One end
C) None
D) All buses
Ans: A
Q69. The control mode of UPFC can be:
A) Voltage control
B) Power flow control
C) Angle control
D) All
Ans: D
Q70. The damping controller for FACTS devices is designed similar to:
A) Power System Stabilizer (PSS)
B) Governor
C) AVR
D) None
Ans: A
Q71. Coordinated control of PSS and FACTS means:
A) Both contribute to system damping without conflict
B) Disable one
C) Independent operation only
D) None
Ans: A
Q72. The washout time constant in damping controller is typically:
A) 5–10 s
B) 0.1 s
C) 100 s
D) None
Ans: A
Q73. The lead-lag compensator in damping control provides:
A) Phase compensation
B) Gain reduction
C) Current limit
D) None
Ans: A
Q74. The input signal to FACTS damping controller is:
A) Speed deviation or power deviation
B) Frequency only
C) Voltage magnitude
D) None
Ans: A
Q75. FACTS damping controller output modulates:
A) Reference voltage or impedance
B) Current magnitude
C) Frequency
D) None
Ans: A
Q76. For inter-area oscillation damping, the best FACTS device is:
A) TCSC or SSSC
B) STATCOM
C) OLTC
D) None
Ans: A
Q77. Local mode oscillations usually occur at:
A) 0.8–2.0 Hz
B) 0.1–0.5 Hz
C) 10–20 Hz
D) None
Ans: A
Q78. Inter-area oscillations usually occur at:
A) 0.1–0.8 Hz
B) 2–5 Hz
C) 5–10 Hz
D) None
Ans: A
Q79. Damping of inter-area oscillations is improved by:
A) Wide-area control using PMU signals
B) Local AVR control
C) Manual adjustment
D) None
Ans: A
Q80. The communication delay in wide-area damping control affects:
A) System stability margin
B) Frequency
C) Line impedance
D) None
Ans: A
Q81. HVDC link assists in damping oscillations by:
A) Power modulation control
B) Frequency control
C) Excitation
D) None
Ans: A
Q82. The control loop in HVDC damping controller is similar to:
A) PSS
B) AVR
C) Governor
D) None
Ans: A
Q83. The damping torque coefficient should be:
A) Positive for stability
B) Negative
C) Zero
D) None
Ans: A
Q84. The synchronizing torque helps maintain:
A) Rotor angle equilibrium
B) Voltage level
C) Frequency
D) None
Ans: A
Q85. In transient stability studies, damping torque is often neglected because:
A) The time period is short
B) Damping is large
C) Rotor is rigid
D) None
Ans: A
Q86. The equal area criterion is used to determine:
A) Transient stability
B) Small-signal stability
C) Voltage stability
D) None
Ans: A
Q87. In equal area criterion, the accelerating area equals:
A) Decelerating area at stability limit
B) Zero
C) Damping torque
D) None
Ans: A
Q88. The mechanical input power is assumed:
A) Constant during fault
B) Variable
C) Zero
D) None
Ans: A
Q89. The electrical output power decreases during:
A) Fault
B) No-load
C) Load increase
D) None
Ans: A
Q90. The system remains stable if:
A) Rotor swings and returns to equilibrium
B) Rotor angle diverges
C) Speed increases continuously
D) None
Ans: A
Q91. Transient energy function method is used for:
A) Direct stability analysis
B) Load flow
C) Short-circuit
D) None
Ans: A
Q92. The energy margin gives:
A) Measure of system stability margin
B) Voltage level
C) Reactive margin
D) None
Ans: A
Q93. The transient energy margin reduces with:
A) Heavy loading
B) Light loading
C) Higher inertia
D) None
Ans: A
Q94. The inertia constant of small generators is:
A) 2–6 MJ/MVA
B) 10–20 MJ/MVA
C) 30–40 MJ/MVA
D) None
Ans: A
Q95. The inertia constant of large turbo-generators is:
A) 6–10 MJ/MVA
B) 1–3 MJ/MVA
C) 20–30 MJ/MVA
D) None
Ans: A
Q96. Higher inertia improves:
A) Stability margin
B) Damping only
C) Voltage
D) None
Ans: A
Q97. In small-signal model, damping ratio ξ =
A)
B)
C)
D) None
Ans: A
Q98. A low damping ratio causes:
A) Sustained oscillations
B) Fast decay
C) Stable operation
D) None
Ans: A
Q99. The system becomes unstable if:
A) Eigenvalues have positive real part
B) Negative real part
C) Zero
D) None
Ans: A
Q100. Improvement of damping ratio and synchronizing torque leads to:
A) Better dynamic stability
B) Reduced voltage
C) Reduced speed
D) None
Ans: A
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