Practice Test Geeks(SOPD) System Operator/Power Dispatching Practice Test
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Grid Reliability Flashcards

7 cards from real SOPD practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Grid Reliability flashcards as text

  1. When a generator experiences a sudden loss of field excitation, what is the primary reliability concern?

    Answer: The unit will absorb reactive power from the system, potentially depressing voltage

    Loss of field excitation causes a generator to operate as an induction generator, absorbing reactive power (Mvars) from the system instead of supplying it, which can depress system voltage.

  2. What is 'load shedding' and when is it used as a reliability tool?

    Answer: Intentionally disconnecting customer load to prevent frequency collapse or cascading outages when generation is insufficient

    Load shedding is a controlled interruption of customer service used as a last resort to balance generation and load, preventing frequency collapse and wider system blackouts.

  3. In power system stability, what type of instability is characterized by growing oscillations in generator rotor angles?

    Answer: Small-signal (oscillatory) instability

    Small-signal instability involves undamped or negatively damped low-frequency oscillations in rotor angles that grow over time, often associated with weak inter-area power system connections.

  4. A transmission line is operating at its Surge Impedance Loading (SIL). What does this condition mean?

    Answer: The line neither consumes nor produces reactive power — it is in reactive power balance

    At SIL, a line's capacitive charging exactly offsets its inductive reactive power consumption, making it reactive-power neutral — a useful reference point for voltage stability analysis.

  5. Which entity has the highest authority during a grid emergency affecting multiple Balancing Authorities?

    Answer: The Reliability Coordinator (RC) for the affected area

    The Reliability Coordinator has the widest area view and highest level of authority during system emergencies, with the ability to direct TOPs and BAs to take specific actions.

  6. What is the purpose of NERC's Disturbance Control Standard (DCS) / BAL-002?

    Answer: To require Balancing Authorities to recover Area Control Error to within limits following a disturbance within a specified time

    BAL-002 requires Balancing Authorities to restore ACE to within defined limits within 15 minutes following a reportable disturbance, ensuring the area does not become a sustained burden on the interconnection.

  7. Which protection relay function is specifically designed to detect and isolate a generator operating out of synchronism with the power system?

    Answer: Out-of-step relay (78)

    The out-of-step relay (ANSI function 78) detects when a generator's rotor has slipped poles and is no longer in synchronism, tripping the unit to protect it and the system from damaging currents.