Transient and dynamic stability studies – MCQs – EE

1. Transient stability refers to:
(A) Long-term voltage regulation
(B) Step response analysis
(C) Generator economic dispatch
(D) The ability of a power system to maintain synchronism immediately after a disturbance

2. Dynamic stability deals with:
(A) Step response only
(B) Load flow convergence
(C) System response to small disturbances over time
(D) Transformer ratings

3. Critical clearing time (CCT) is:
(A) Transformer tap delay
(B) Generator inertia
(C) Maximum time a fault can remain before losing synchronism
(D) Minimum load current

4. Swing equation in stability studies models:
(A) Voltage drop across the network
(B) Load flow only
(C) Generator rotor angle dynamics
(D) Reactive power variation

5. A fault on a transmission line can cause:
(A) Step response analysis
(B) Constant system frequency
(C) Transient instability
(D) Only load shedding

6. Power angle curve helps to:
(A) Plot voltage profiles
(B) Solve short-circuit currents
(C) Determine maximum power transfer
(D) Control reactive power only

7. In dynamic stability, small-signal analysis is used for:
(A) RMS voltage measurement
(B) Minor disturbances
(C) Three-phase faults
(D) Load flow only

8. Transient stability is mainly analyzed for:
(A) Step response only
(B) Generator start-up only
(C) Large disturbances such as faults or line trips
(D) Voltage sag only

9. In transient stability simulation, the system is modeled using:
(A) Only algebraic equations
(B) Only reactive power flows
(C) Differential equations of generator dynamics
(D) Only voltage magnitudes

10. Swing equation includes:
(A) Only load currents
(B) Generator inertia and accelerating power
(C) Only voltage
(D) Only reactive power

11. Critical clearing angle is related to:
(A) Line impedance
(B) Rotor angle when a fault is cleared
(C) Step response time
(D) Load voltage

12. Equal area criterion is applied for:
(A) Transformer rating calculation
(B) Transient stability of a single-machine infinite bus system
(C) Only load flow
(D) Dynamic stability of small signals only

13. In power system simulation, numerical integration methods include:
(A) Only Simpson’s rule
(B) Euler and Runge-Kutta
(C) Gauss-Seidel only
(D) Bisection only

14. Rotor angle deviation is a key indicator of:
(A) Step response magnitude
(B) Voltage regulation
(C) System stability
(D) Load current

15. Transient instability occurs when:
(A) Voltage remains constant
(B) Load demand decreases
(C) Generators lose synchronism
(D) Frequency is fixed

16. Dynamic stability requires consideration of:
(A) Only step response
(B) Excitation system and governor dynamics
(C) Only line impedance
(D) Only load currents

17. PSCAD or ETAP can be used to:
(A) Plot bar charts
(B) Simulate transient stability
(C) Only solve load flow
(D) Compute RMS voltage only

18. Damping torque contributes to:
(A) Voltage drop
(B) Transient instability
(C) Short-circuit current
(D) Dynamic stability

19. Small-disturbance stability is important for:
(A) Step response only
(B) Long-term oscillations after minor load changes
(C) Only RMS analysis
(D) Three-phase fault only

20. In transient stability studies, generator models often include:
(A) Only load impedances
(B) Rotor inertia, excitation, and governor systems
(C) Only voltage regulators
(D) Only transformer ratings

21. Critical clearing time is measured in:
(A) Watts
(B) Voltages
(C) Ohms
(D) Seconds

22. Transient stability analysis helps in:
(A) Measuring transformer taps
(B) Determining if the system remains synchronized after a fault
(C) Calculating load currents only
(D) Plotting histograms

23. Modal analysis is used in dynamic stability to:
(A) Step response only
(B) Voltage sag analysis
(C) Identify oscillatory modes of the system
(D) Solve short-circuit currents

24. Power system stabilizers (PSS) are used to:
(A) Only regulate voltage
(B) Plot step response
(C) Improve dynamic stability
(D) Measure load current

25. Transient energy function method is applied to:
(A) Only short-circuit analysis
(B) Step response analysis
(C) Load flow only
(D) Assess system stability after a large disturbance

26. Swing curve represents:
(A) Frequency versus power
(B) Voltage versus current
(C) Load versus generation
(D) Rotor angle versus time

27. Multi-machine stability studies are more complex because:
(A) Step response is fixed
(B) Only single-machine data is used
(C) Interaction among multiple machines must be considered
(D) Load flow is irrelevant

28. Transient voltage dips are usually caused by:
(A) Transformer tap settings
(B) Faults or switching operations
(C) Load flow only
(D) Frequency measurement

29. Dynamic stability can be affected by:
(A) Excitation system parameters
(B) Only transmission line lengths
(C) Only generator rating
(D) Only bus voltages

30. The main purpose of transient and dynamic stability studies is to:
(A) Only compute RMS voltages
(B) Measure load currents
(C) Only plot signals
(D) Ensure safe and continuous operation of power systems