NERC final exam SOS
A Balancing Authority has a Net Interchange Schedule of -250 MWs from 1200 to 1600 on
a summer day. The Net Interchange Actual for those same hours respectively were -230
MW, -275 MW, -250 MW and -270 MW. What was the Balancing Authority's Inadvertent
Interchange for the 4-hour period?
a. 25 MWs in
b. 25 MWs out
c. 6 MWs out
d. 6 MWs in - ANS a. 25 MWs in
Feedback: Inadvertent calculation is after the hour and the difference between Net
Interchange Actual and Net Interchange Scheduled.Inadvertent for hour 1: (-230 ) - (-250)
= +20Inadvertent for hour 2: (-275) - (-250) = -25Inadvertent for hour 3: (-250) - (-250) =
0Inadvertent for hour 4: (-270) - (-250) = -20Net for the period = - 25
\A Balancing Authority has a normal generation capacity of approximately 9400 MW and
its most severe single contingency is an 800 MW coal-fired steam unit. At 1430, with an
ACE value of 20 MW, a 600-MW generator trips off-line as the result of a generator
differential. This resulted in a large negative ACE for the Balancing Authority. What value
must the ACE return to and in what time frame to avoid a DCS violation?
a. Must return ACE to 0 MW in 15 minutes.
b. Must return ACE to 0 MW in 10 minutes.
c. This does not constitute a reportable disturbance.
d. Must return ACE to 20 MW in 15 minutes. - ANS c. This does not constitute a
reportable disturbance.
Feedback: The DCS criteria applies to a sudden loss of generation that exceeds 80% of
the Balancing Authorities most severe single contingency, or in this case 80% of 800
MWs which is 640 MWs. Since only 600 MWs were lost, the DCS criteria does not apply.
However, the BA should return ACE as quickly as possible.BAL-002
\A Balancing Authority has a normal generation capacity of approximately 9400 MW and
its most severe single contingency is an 800 MW coal-fired steam unit. At 1430, with an
ACE value of 20 MW, a 600-MW generator trips off-line as the result of a generator
differential. This resulted in a large negative ACE for the Balancing Authority. What value
must the ACE return to and in what time frame to avoid a DCS violation?
a. This does not constitute a reportable disturbance.
b. Must return ACE to 0 MW in 10 minutes.
c. Must return ACE to 20 MW in 15 minutes.
,d. Must return ACE to 0 MW in 15 minutes. - ANS a. This does not constitute a reportable
disturbance.
Feedback: The DCS criteria applies to a sudden loss of generation that exceeds 80% of
the Balancing Authorities most severe single contingency, or in this case 80% of 800
MWs which is 640 MWs. Since only 600 MWs were lost, the DCS criteria does not apply.
However, the BA should return ACE as quickly as possible.BAL-002
\A Balancing Authority is experiencing a high demand day with several generators
experiencing forced outages. The Balancing Authority is able to maintain sufficient
Contingency Reserves by initiating its Operating Plan involving Interruptible Load. What
level EEA, if any, should be requested of the Balancing Authority's Reliability Coordinator
?
a. EEA 3
b. No EEA is needed
c. EEA 1
d. EEA 2 - ANS d. EEA 2
Feedback: EOP-011, Attachment 1.2. EEA 2 — Load management procedures in effect.
Circumstances: * The Balancing Authority is no longer able to provide its expected
energy requirements and is an energy deficient Balancing Authority. * An energy
deficient Balancing Authority has implemented its Operating Plan(s) to mitigate
Emergencies. * An energy deficient Balancing Authority is still able to maintain minimum
Contingency Reserve requirements.Since there is no mention of firm load shed , this
would not be an EEA 3. A level 3 EEA is reserved for situations where load shed has
taken place or is imminent. Interruptible Load is not the same thing as firm load shed.
\A Balancing Authority that is operating asynchronously (separated from the
Interconnection) should switch its AGC to which mode __________.
a. flat tie-line control
b. tie line bias control
c. manual control
d. flat frequency control - ANS d. flat frequency control
Feedback: BAL-005 Automatic Generation Control
\A Balancing Authority with several units offline anticipates a capacity shortage during
the afternoon peak due to unseasonal temperature forecast. What should the BA
consider first?
a. Curtail interruptible customers
b. Postpone or cancel unit maintenance
c. Implement voltage reduction procedures
d. Drop load - ANS b. Postpone or cancel unit maintenance
, Feedback: All listed actions may be appropriate at some point if the capacity shortage
develops. However, the question asks what should be done first, and postponing outages
would be the correct answer.
\A conductor is rated for 180 MVA. The current transformer at one end is rated at 160
MVA, and the bus is rated at 200 MVA. What is the MVA limit for this transmission line?
a. 180 MVA
b. 160 MVA
c. 200 MVA
d. 100 MVA - ANS b. 160 MVA
Feedback:
(NERC TOP-001) Each Transmission Operator shall operate to the most limiting
parameter in instances where there is a difference in SOLs.
\A major transmission line has become overloaded and the transmission operator has
taken actions to unload the line. However, the overload persists, and the equipment is
now in imminent danger of damage. What is the next action to take?
a. Request a Transmission loading relief procedure
b. Request permission from the RC to open the line.
c. Disconnect the overloaded line and notify the RC and affected Transmission
Operators.
d. Separate from the Interconnection - ANS c. Disconnect the overloaded line and notify
the RC and affected Transmission Operators.
Feedback: When a transmission line exceeds its system operating limits, a system
operator will act to relieve the overloaded, if that action is not sufficient then additional
emergency actions may be necessary rather than risk an uncontrolled outage or
separation. If time permits the system operator will determine the effects prior to
disconnecting the line and notify the RC and affected TOPs.
\A radial transmission line feeding a load is overloaded. The Transmission Operator must
do which of the following to unload the line?
a. Shed load at the end of the line
b. Raise interchange schedule
c. Lower interchange schedule
d. Re-dispatch generation - ANS a. Shed load at the end of the line
Feedback: The word radial in this question is key. Shedding load is the only possible
action to reduce loading on the line.
\A Reliability Coordinator receives notification from a Balancing Authority within its
Reliability Coordinator area that the BA is experiencing a potential Energy Emergency.
The RC shall initiate the Energy Emergency Alert (EEA) process as detailed in
A Balancing Authority has a Net Interchange Schedule of -250 MWs from 1200 to 1600 on
a summer day. The Net Interchange Actual for those same hours respectively were -230
MW, -275 MW, -250 MW and -270 MW. What was the Balancing Authority's Inadvertent
Interchange for the 4-hour period?
a. 25 MWs in
b. 25 MWs out
c. 6 MWs out
d. 6 MWs in - ANS a. 25 MWs in
Feedback: Inadvertent calculation is after the hour and the difference between Net
Interchange Actual and Net Interchange Scheduled.Inadvertent for hour 1: (-230 ) - (-250)
= +20Inadvertent for hour 2: (-275) - (-250) = -25Inadvertent for hour 3: (-250) - (-250) =
0Inadvertent for hour 4: (-270) - (-250) = -20Net for the period = - 25
\A Balancing Authority has a normal generation capacity of approximately 9400 MW and
its most severe single contingency is an 800 MW coal-fired steam unit. At 1430, with an
ACE value of 20 MW, a 600-MW generator trips off-line as the result of a generator
differential. This resulted in a large negative ACE for the Balancing Authority. What value
must the ACE return to and in what time frame to avoid a DCS violation?
a. Must return ACE to 0 MW in 15 minutes.
b. Must return ACE to 0 MW in 10 minutes.
c. This does not constitute a reportable disturbance.
d. Must return ACE to 20 MW in 15 minutes. - ANS c. This does not constitute a
reportable disturbance.
Feedback: The DCS criteria applies to a sudden loss of generation that exceeds 80% of
the Balancing Authorities most severe single contingency, or in this case 80% of 800
MWs which is 640 MWs. Since only 600 MWs were lost, the DCS criteria does not apply.
However, the BA should return ACE as quickly as possible.BAL-002
\A Balancing Authority has a normal generation capacity of approximately 9400 MW and
its most severe single contingency is an 800 MW coal-fired steam unit. At 1430, with an
ACE value of 20 MW, a 600-MW generator trips off-line as the result of a generator
differential. This resulted in a large negative ACE for the Balancing Authority. What value
must the ACE return to and in what time frame to avoid a DCS violation?
a. This does not constitute a reportable disturbance.
b. Must return ACE to 0 MW in 10 minutes.
c. Must return ACE to 20 MW in 15 minutes.
,d. Must return ACE to 0 MW in 15 minutes. - ANS a. This does not constitute a reportable
disturbance.
Feedback: The DCS criteria applies to a sudden loss of generation that exceeds 80% of
the Balancing Authorities most severe single contingency, or in this case 80% of 800
MWs which is 640 MWs. Since only 600 MWs were lost, the DCS criteria does not apply.
However, the BA should return ACE as quickly as possible.BAL-002
\A Balancing Authority is experiencing a high demand day with several generators
experiencing forced outages. The Balancing Authority is able to maintain sufficient
Contingency Reserves by initiating its Operating Plan involving Interruptible Load. What
level EEA, if any, should be requested of the Balancing Authority's Reliability Coordinator
?
a. EEA 3
b. No EEA is needed
c. EEA 1
d. EEA 2 - ANS d. EEA 2
Feedback: EOP-011, Attachment 1.2. EEA 2 — Load management procedures in effect.
Circumstances: * The Balancing Authority is no longer able to provide its expected
energy requirements and is an energy deficient Balancing Authority. * An energy
deficient Balancing Authority has implemented its Operating Plan(s) to mitigate
Emergencies. * An energy deficient Balancing Authority is still able to maintain minimum
Contingency Reserve requirements.Since there is no mention of firm load shed , this
would not be an EEA 3. A level 3 EEA is reserved for situations where load shed has
taken place or is imminent. Interruptible Load is not the same thing as firm load shed.
\A Balancing Authority that is operating asynchronously (separated from the
Interconnection) should switch its AGC to which mode __________.
a. flat tie-line control
b. tie line bias control
c. manual control
d. flat frequency control - ANS d. flat frequency control
Feedback: BAL-005 Automatic Generation Control
\A Balancing Authority with several units offline anticipates a capacity shortage during
the afternoon peak due to unseasonal temperature forecast. What should the BA
consider first?
a. Curtail interruptible customers
b. Postpone or cancel unit maintenance
c. Implement voltage reduction procedures
d. Drop load - ANS b. Postpone or cancel unit maintenance
, Feedback: All listed actions may be appropriate at some point if the capacity shortage
develops. However, the question asks what should be done first, and postponing outages
would be the correct answer.
\A conductor is rated for 180 MVA. The current transformer at one end is rated at 160
MVA, and the bus is rated at 200 MVA. What is the MVA limit for this transmission line?
a. 180 MVA
b. 160 MVA
c. 200 MVA
d. 100 MVA - ANS b. 160 MVA
Feedback:
(NERC TOP-001) Each Transmission Operator shall operate to the most limiting
parameter in instances where there is a difference in SOLs.
\A major transmission line has become overloaded and the transmission operator has
taken actions to unload the line. However, the overload persists, and the equipment is
now in imminent danger of damage. What is the next action to take?
a. Request a Transmission loading relief procedure
b. Request permission from the RC to open the line.
c. Disconnect the overloaded line and notify the RC and affected Transmission
Operators.
d. Separate from the Interconnection - ANS c. Disconnect the overloaded line and notify
the RC and affected Transmission Operators.
Feedback: When a transmission line exceeds its system operating limits, a system
operator will act to relieve the overloaded, if that action is not sufficient then additional
emergency actions may be necessary rather than risk an uncontrolled outage or
separation. If time permits the system operator will determine the effects prior to
disconnecting the line and notify the RC and affected TOPs.
\A radial transmission line feeding a load is overloaded. The Transmission Operator must
do which of the following to unload the line?
a. Shed load at the end of the line
b. Raise interchange schedule
c. Lower interchange schedule
d. Re-dispatch generation - ANS a. Shed load at the end of the line
Feedback: The word radial in this question is key. Shedding load is the only possible
action to reduce loading on the line.
\A Reliability Coordinator receives notification from a Balancing Authority within its
Reliability Coordinator area that the BA is experiencing a potential Energy Emergency.
The RC shall initiate the Energy Emergency Alert (EEA) process as detailed in
