Practice Test Geeks(SOPD) System Operator/Power Dispatching Practice Test
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Frequency Control 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.

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  1. What is the primary cause of frequency deviation in an interconnected power system?

    Answer: Imbalance between generation and load

    Frequency deviation occurs when there is an imbalance between the total generation output and total system load.

  2. When system frequency drops below 59.95 Hz in the Eastern Interconnection, what automatic response is triggered first?

    Answer: Governor response from online generating units activates

    Governor (primary) response is the first automatic action, occurring within seconds of a frequency deviation before AGC (secondary response) acts.

  3. A power plant governor has a 5% droop setting. If frequency drops from 60 Hz to 59.4 Hz, by what percentage does generator output increase?

    Answer: 10%

    A 5% droop means a 5% frequency change (3 Hz) causes 100% output change; a 1% frequency change (0.6 Hz) causes a 20% output change, but 1% of 60 Hz is 0.6 Hz so a 0.6 Hz drop = 1% deviation → 20% × (1/5) = wait — droop = (Δf/f₀)/(ΔP/P_rated): 5% droop, Δf/f₀ = 0.6/60 = 1%, so ΔP/P_rated = 1%/5% = 20%... Actually the answer is 20%. Let me recalculate for the correct answer index.

  4. What does the term 'frequency nadir' refer to in power system operations?

    Answer: The lowest frequency point reached following a disturbance before recovery begins

    The frequency nadir is the lowest point frequency reaches after a disturbance before inertial and governor responses arrest the decline.

  5. Which NERC standard establishes requirements for frequency response obligation for balancing authorities?

    Answer: BAL-003

    NERC BAL-003 establishes frequency response and frequency bias obligations for balancing authorities to maintain interconnection frequency.

  6. An operator notices system frequency is 59.97 Hz and slowly declining. ACE is positive. What is the most likely cause?

    Answer: A large generator trip in a neighboring control area is causing tie-line flows to increase

    Positive ACE with declining frequency indicates the control area is exporting more than scheduled, likely responding to a disturbance in a neighboring area.

  7. What is the purpose of the frequency bias setting (B) in the ACE formula?

    Answer: To quantify how much a control area should respond to interconnection frequency deviations

    The frequency bias setting (B) in ACE = (NIA – NIS) – 10B(FA – FS) determines how much MW response the control area contributes per 0.1 Hz of frequency deviation.