RELIABILITY TEST BANK EXAM
QUESTIONS WITH CORRECT
ANSWERS
Interconnection frequency is 59.80 Hz. Your ACE is a large negative value and your
AGC is pulsing your units down. What should you do?
Place AGC in constant frequency control.
Leave AGC in operation but investigate.
Place AGC in flat tie line control.
Suspend AGC and investigate. - Answer-Suspend AGC and investigate.
In this scenario, the AGC clearly is not operating correctly (pulsing units down when
ACE is negative) and given that the frequency has dramatically declined to 59.80 Hz
that has an adverse impact to the reliability of the Interconnection. Therefore,
suspending AGC and going to manual control to adjust generation is the
recommended course of action.
You experience a full system shutdown. You are in the process of restoring load and
you are concerned about re-collapsing the system. Which is the best approach in the
restoration process that will help ensure your system will be restored successfully?
If the system has stabilized at below 60 HZ, shed 15% - 20% of the load to raise the
frequency to 61 HZ.
Avoid energizing loads in excess of 5% of the online generation capacity of the
system.
Operating reserves should be maintained to cover the largest generator currently in
service.
Maintain frequency between 59.5 HZ and 60.5 HZ. - Answer-Avoid energizing loads
in excess of 5% of the online generation capacity of the system.
Increasing load too rapidly could result in a re-shutdown of the system. The thumb
rule for load restoration is blocks of load not to exceed 5% of the online generation
capacity of the system.
After a major disturbance, Interconnection frequency is remaining around 59.92Hz,
your Balancing Authority's ACE is 0 and you have 200 MW of extra generation. What
should the Balancing Authority system operator do?
Offer assistance to entities needing it
Shed Load
Change the AGC mode to Flat Frequency
Increase Generation - Answer-Offer assistance to entities needing it.
After a disturbance where frequency declines significantly, the entire Interconnection
will react (automatically) with governors increasing generation and load decreasing
slightly. Load and Generation will rebalance at a lower frequency until generation is
,increased to return the Interconnection frequency to 60.00 Hz. The best answer is to
offer assistance to the deficient Balancing Authority by offering the 200 MW of
reserves in a bilateral interchange transaction to help restore generation and load
balance in the Interconnection.
Why are high transmission system voltages a problem during system restoration?
Because of the excessive MVAR supply from generators.
Because of the excessive MVAR supply from energizing transmission lines.
Because of shunt reactors that were left in service after the system collapse.
Because of insufficient MVAR supply from generators that tripped off. - Answer-
Because of the excessive MVAR supply from energizing transmission lines.
EPRI 2009 Power System Dynamics Tutorial Chapter 11
During a system restoration, what is the system operators priority?
Interconnection frequency
Restoration of interchange
Restoration of off-site startup power to generating facilities
Restoration of customer load - Answer-Restoration of off-site startup power to
generating facilities.
EPRI - Power System Restoration 11-62 It is critical to ensure the off-site power to
generating facilities to avoid damage to the generator.
A report shall be submitted to NERC following the shedding of at least how much
firm load?
200 MW
100 MW
300 MW
50 MW - Answer-100 MW.
EOP-004 states, Firm load shedding of 100 MW or more to maintain the continuity of
the bulk electric system."
Firm load shedding of 100 MW or more to maintain the continuity of the bulk electric
system also requires a report to DOE. NERC will accept the same report.
Which of the below items does an RC verify prior to approving the synchronization of
two islands?
1. Frequency of the Islands are matched
2. Load is balanced for the two areas
3. Load and generation is balanced for the two areas
4. Synchronizing equipment exists at the tie point.
1,3 and 4
1, 2, and 3
1,2 and 4
2,3 and 4 - Answer-1,3 and 4.
,EOP-006, System Restoration Coordination: R8: The Reliability Coordinator shall
coordinate or authorize re-synchronizing islanded areas that bridge boundaries
between Transmission Operators or Reliability Coordinators. If the re-
synchronization cannot be completed as expected the Reliability Coordinator shall
utilize its restoration plan strategies to facilitate re-synchronization.
An 800 MW generator trips in a Balancing Authority external to your Balancing
Authority Area. Which of the following indications would you expect to see in your
area?
Frequency would drop, and ACE would remain relatively unchanged.
ACE would drop to approximately -800 MW.
Net Actual Interchange would decrease significantly.
Frequency would drop, and ACE would increase significantly. - Answer-Frequency
would drop, and ACE would remain relatively unchanged.
Since the disturbance is external to the BA, ACE should change very little. The Net
Actual Interchange would increase as the natural frequency response of the BA
allows it to provide assistance to the Interconnection in arresting the frequency drop.
The Frequency Bias portion of the ACE equation assists by canceling out the
increase in ACE caused by the Net Actual Interchange increasing, assuming the
Bias is set correctly.
NERC requires a report to be submitted following the shedding of at least how much
firm load?
200 MW
50 MW
100 MW
300 MW - Answer-100 MW.
EOP-004, Disturbance Reporting.
You are a Reliability Coordinator experiencing a flow gate that has become
overloaded because a parallel 345 kV line has relayed out causing an SOL violation.
What would you do to relieve this violation?
Implement the appropriate transmission loading relief procedures
Order the line be placed back in service within 30 minutes.
Notify the affected Reliability Coordinator and ask them to resolve this issue
Issue a warning to the Transmission Operators that lost the 345 kV line. - Answer-
Implement the appropriate transmission loading relief procedures.
Megawatts flow on the path of lowest impedance. When the 345 kV line relayed out,
the path of lowest impedance is the flow gate that has now become in violation of an
SOL and/or IROL. The Reliability Coordinator has the authority to relieve any
transmission facility that is an actual or potential reliability concern. One of the
options available is to use is transmission loading relief procedures which curtails
interchange that contribute to the line overload.
, Which indicators alert operator to potential emergency conditions?
Sudden increase in call volume
Sudden changes in system frequency and voltage
Sudden increase in system load
Sudden changes in Interchange transactions - Answer-Sudden changes in system
frequency and voltage.
Voltage reduction for load relief should be made on the __________.
Transmission System
Distribution system
Tie-lines with other Balancing Authority Areas
Entire Interconnection simultaneously - Answer-Distribution system.
Normally, voltage reduction for load relief should be made on the distribution system.
Voltage reduction on the sub transmission or transmission system may be effective
in reducing load; however, voltage reduction should not be made on the transmission
system unless the system has been isolated from the Interconnection. This is
because implementing a voltage reduction on a single system that is still
interconnected to its neighbors will have a negative impact on the voltage of
neighboring systems as MVAr move from the neighboring systems to the system
attempting to reduce its voltage. - NERC Standard TOP-001
The Interconnections is not experience any disturbances or overloads. A Balancing
Authority notifies the Reliability Coordinator that the projected load in a Balancing
Area for the next three hours (over the morning peak) is trending above the available
generation that had been committed for the day. Operating Reserves will be required
to be converted into energy to cover the shortfall. What is the most likely cause of
the shortfall?
The largest capacity generator in the Balancing Area tripped off line.
The Load Forecast for the day was greatly underestimated.
There was a curtailment of the largest import on the Interchange Schedule.
A generator operator failed to notify the Balancing Authority that one of their
generators was de-rated by 30% of its capacity. - Answer-The Load Forecast for the
day was greatly underestimated.
Operating reserves are that capability above firm system demand required to provide
for regulation, load forecasting error, equipment forced and scheduled outages and
local area protection. It consists of spinning and non-spinning reserve.
If an hourly load forecast greatly underestimate the load, a shortfall of available
generation to cover load and reserves is likely due to not committing enough
generation for the day. The instantaneous loss of generation, cutting Interchange
Scheduled purchases and de-rating generators are covered within the reserve
requirement. If reserves are needed to cover load, then the BA is not meeting load
and reserves requirements.
QUESTIONS WITH CORRECT
ANSWERS
Interconnection frequency is 59.80 Hz. Your ACE is a large negative value and your
AGC is pulsing your units down. What should you do?
Place AGC in constant frequency control.
Leave AGC in operation but investigate.
Place AGC in flat tie line control.
Suspend AGC and investigate. - Answer-Suspend AGC and investigate.
In this scenario, the AGC clearly is not operating correctly (pulsing units down when
ACE is negative) and given that the frequency has dramatically declined to 59.80 Hz
that has an adverse impact to the reliability of the Interconnection. Therefore,
suspending AGC and going to manual control to adjust generation is the
recommended course of action.
You experience a full system shutdown. You are in the process of restoring load and
you are concerned about re-collapsing the system. Which is the best approach in the
restoration process that will help ensure your system will be restored successfully?
If the system has stabilized at below 60 HZ, shed 15% - 20% of the load to raise the
frequency to 61 HZ.
Avoid energizing loads in excess of 5% of the online generation capacity of the
system.
Operating reserves should be maintained to cover the largest generator currently in
service.
Maintain frequency between 59.5 HZ and 60.5 HZ. - Answer-Avoid energizing loads
in excess of 5% of the online generation capacity of the system.
Increasing load too rapidly could result in a re-shutdown of the system. The thumb
rule for load restoration is blocks of load not to exceed 5% of the online generation
capacity of the system.
After a major disturbance, Interconnection frequency is remaining around 59.92Hz,
your Balancing Authority's ACE is 0 and you have 200 MW of extra generation. What
should the Balancing Authority system operator do?
Offer assistance to entities needing it
Shed Load
Change the AGC mode to Flat Frequency
Increase Generation - Answer-Offer assistance to entities needing it.
After a disturbance where frequency declines significantly, the entire Interconnection
will react (automatically) with governors increasing generation and load decreasing
slightly. Load and Generation will rebalance at a lower frequency until generation is
,increased to return the Interconnection frequency to 60.00 Hz. The best answer is to
offer assistance to the deficient Balancing Authority by offering the 200 MW of
reserves in a bilateral interchange transaction to help restore generation and load
balance in the Interconnection.
Why are high transmission system voltages a problem during system restoration?
Because of the excessive MVAR supply from generators.
Because of the excessive MVAR supply from energizing transmission lines.
Because of shunt reactors that were left in service after the system collapse.
Because of insufficient MVAR supply from generators that tripped off. - Answer-
Because of the excessive MVAR supply from energizing transmission lines.
EPRI 2009 Power System Dynamics Tutorial Chapter 11
During a system restoration, what is the system operators priority?
Interconnection frequency
Restoration of interchange
Restoration of off-site startup power to generating facilities
Restoration of customer load - Answer-Restoration of off-site startup power to
generating facilities.
EPRI - Power System Restoration 11-62 It is critical to ensure the off-site power to
generating facilities to avoid damage to the generator.
A report shall be submitted to NERC following the shedding of at least how much
firm load?
200 MW
100 MW
300 MW
50 MW - Answer-100 MW.
EOP-004 states, Firm load shedding of 100 MW or more to maintain the continuity of
the bulk electric system."
Firm load shedding of 100 MW or more to maintain the continuity of the bulk electric
system also requires a report to DOE. NERC will accept the same report.
Which of the below items does an RC verify prior to approving the synchronization of
two islands?
1. Frequency of the Islands are matched
2. Load is balanced for the two areas
3. Load and generation is balanced for the two areas
4. Synchronizing equipment exists at the tie point.
1,3 and 4
1, 2, and 3
1,2 and 4
2,3 and 4 - Answer-1,3 and 4.
,EOP-006, System Restoration Coordination: R8: The Reliability Coordinator shall
coordinate or authorize re-synchronizing islanded areas that bridge boundaries
between Transmission Operators or Reliability Coordinators. If the re-
synchronization cannot be completed as expected the Reliability Coordinator shall
utilize its restoration plan strategies to facilitate re-synchronization.
An 800 MW generator trips in a Balancing Authority external to your Balancing
Authority Area. Which of the following indications would you expect to see in your
area?
Frequency would drop, and ACE would remain relatively unchanged.
ACE would drop to approximately -800 MW.
Net Actual Interchange would decrease significantly.
Frequency would drop, and ACE would increase significantly. - Answer-Frequency
would drop, and ACE would remain relatively unchanged.
Since the disturbance is external to the BA, ACE should change very little. The Net
Actual Interchange would increase as the natural frequency response of the BA
allows it to provide assistance to the Interconnection in arresting the frequency drop.
The Frequency Bias portion of the ACE equation assists by canceling out the
increase in ACE caused by the Net Actual Interchange increasing, assuming the
Bias is set correctly.
NERC requires a report to be submitted following the shedding of at least how much
firm load?
200 MW
50 MW
100 MW
300 MW - Answer-100 MW.
EOP-004, Disturbance Reporting.
You are a Reliability Coordinator experiencing a flow gate that has become
overloaded because a parallel 345 kV line has relayed out causing an SOL violation.
What would you do to relieve this violation?
Implement the appropriate transmission loading relief procedures
Order the line be placed back in service within 30 minutes.
Notify the affected Reliability Coordinator and ask them to resolve this issue
Issue a warning to the Transmission Operators that lost the 345 kV line. - Answer-
Implement the appropriate transmission loading relief procedures.
Megawatts flow on the path of lowest impedance. When the 345 kV line relayed out,
the path of lowest impedance is the flow gate that has now become in violation of an
SOL and/or IROL. The Reliability Coordinator has the authority to relieve any
transmission facility that is an actual or potential reliability concern. One of the
options available is to use is transmission loading relief procedures which curtails
interchange that contribute to the line overload.
, Which indicators alert operator to potential emergency conditions?
Sudden increase in call volume
Sudden changes in system frequency and voltage
Sudden increase in system load
Sudden changes in Interchange transactions - Answer-Sudden changes in system
frequency and voltage.
Voltage reduction for load relief should be made on the __________.
Transmission System
Distribution system
Tie-lines with other Balancing Authority Areas
Entire Interconnection simultaneously - Answer-Distribution system.
Normally, voltage reduction for load relief should be made on the distribution system.
Voltage reduction on the sub transmission or transmission system may be effective
in reducing load; however, voltage reduction should not be made on the transmission
system unless the system has been isolated from the Interconnection. This is
because implementing a voltage reduction on a single system that is still
interconnected to its neighbors will have a negative impact on the voltage of
neighboring systems as MVAr move from the neighboring systems to the system
attempting to reduce its voltage. - NERC Standard TOP-001
The Interconnections is not experience any disturbances or overloads. A Balancing
Authority notifies the Reliability Coordinator that the projected load in a Balancing
Area for the next three hours (over the morning peak) is trending above the available
generation that had been committed for the day. Operating Reserves will be required
to be converted into energy to cover the shortfall. What is the most likely cause of
the shortfall?
The largest capacity generator in the Balancing Area tripped off line.
The Load Forecast for the day was greatly underestimated.
There was a curtailment of the largest import on the Interchange Schedule.
A generator operator failed to notify the Balancing Authority that one of their
generators was de-rated by 30% of its capacity. - Answer-The Load Forecast for the
day was greatly underestimated.
Operating reserves are that capability above firm system demand required to provide
for regulation, load forecasting error, equipment forced and scheduled outages and
local area protection. It consists of spinning and non-spinning reserve.
If an hourly load forecast greatly underestimate the load, a shortfall of available
generation to cover load and reserves is likely due to not committing enough
generation for the day. The instantaneous loss of generation, cutting Interchange
Scheduled purchases and de-rating generators are covered within the reserve
requirement. If reserves are needed to cover load, then the BA is not meeting load
and reserves requirements.
