NERC RC Exam Questions and Correct
Answers
What is ACE?
✓ ~~~ (NIa - NIs) - 10β(fa - fs) - Ime
Calculated every 6 seconds
Uses Tie line Frequency Bias
What is Tie line deviation?
✓ ~~~ Largest offset to ACE
What is NIA?
✓ ~~~ Net Interchange Actual (sum of all tie-line values)
What is NIS?
✓ ~~~ Net Interchange Scheduled (sum of all interchange schedules)
What is the multiplier for frequency bias?
✓ ~~~ 10
What is β?
✓ ~~~ Frequency bias - represented as negative number in ACE calculation - reflects
area natural response to frequency changes (Inertia, Governor, Load) - atleast 1% of
annual peak load for areas with native load - 1% of peak generation output for area
with no load
,What is FA?
✓ ~~~ Frequency Actual
What is FS?
✓ ~~~ Frequency Schedule - normally 60.00 HZ except for time corrections - +/- .02
Hz
What is IME?
✓ ~~~ Meter error
fudge factor
used for inadvertent bilateral payback
Negligible
What should be done if unable to calculate ACE for 30 minutes?
✓ ~~~ Contact RC
How often should time error and frequency devices be checked/calibrated?
✓ ~~~ Annually
Negative Ace
✓ ~~~ The BA is Undergenerating
Positve ACE
, ✓ ~~~ The BA is Overgenerating
What happens during Internal Loss of Load?
✓ ~~~ Frequency and ACE increase.
What happens during External Loss of Load?
✓ ~~~ Frequency increases, no change in ACE.
What is the Frequency Bias Setting?
✓ ~~~ Monthly average >= 1% of estimated yearly peak demand per 0.1 Hz
When should the Balancing Authority recalculate its Frequency Bias Setting?
✓ ~~~ By January 1 of each year
What happens when there is internal generation loss?
✓ ~~~ Frequency and ACE drop, tie-line flows increase into the system
What happens when there is external generation loss?
✓ ~~~ Frequency drops, no change in ACE, net tie-line flows increase out of the
system
What happens when Frequency bias setting is lower than frequency response?
✓ ~~~ ACE will be positive causing the AGC to lower generation
, What is the percentage change in load required for a 1% change in frequency?
✓ ~~~ 1% - 2% change in load
What is the load reduction when Transmission Customer Voltage is reduced by 5%?
✓ ~~~ Load will reduce by 3%
What happens to ACE and AGC when the frequency bias setting is set to a less
negative value than the frequency response of a Balancing Authority and a
frequency increase is caused by a sudden loss of load in an external balancing
area?
✓ ~~~ ACE will be a negative value and AGC will increase generation
What happens to ACE and AGC when the frequency bias setting is less negative
than the frequency response of a Balancing Authority and a frequency decline is
caused by a sudden loss of generation in an external balancing area?
✓ ~~~ ACE will be a positive value and AGC will lower generation
What is the normal schedule frequency?
✓ ~~~ 60.00 Hz
What is the frequency correction for fast clock schedule?
✓ ~~~ 59.98 Hz
What is the frequency corrections for a slow clock schedule?
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