Download RELIABILITY EXAM WITH 100% CORRECT ANSWERS 2026 and more Exams Nursing in PDF only on Docsity!
RELIABILITY EXAM WITH 100%
CORRECT ANSWERS 2026
A Balancing Authority has a sudden loss of a large block of load in its area. This loss will be seen instantaneously in the change of which of the following values?
- Actual Net Interchange
- Scheduled Frequency
- Scheduled Net Interchange
- Area Control Error 1 & 4 3 & 4 1 & 3 4 only correct answer 1 & 4. Due to the loss of load in the area, the BA will have excess generation and the excess will be exported into the Interconnection through the tie lines. This will cause the NIa to increase. Scheduled Frequency and Interchange only change when changed by an operator. A Balancing Authority has twenty units on governor control. The units have different capacities that range from 200 MW to 1000 MW and droop settings from 2% to 5%. The biggest adjustments in megawatt output in response to a frequency disturbance will be provided by units that have _______________.
small capacity and small droop setting large capacity and small droop setting large capacity and large droop setting small capacity and large droop setting correct answer large capacity and small droop setting When a generator synchronizes to the Interconnection, it couples itself to hundreds of other machines rotating at the same electrical speed. All generators should have a droop feature added to their governor. This will allow the generators to respond to the frequency deviation in proportion to their size whenever there is a disturbance or load-resource mismatch. What controls a generator's response is the governor "droop setting." The smaller the droop the closer a generator gets to being an isochronous generator. A 4 % droop gives more generator response to frequency variations than a 5% droop. - NERC training document "Understand and Calculate Frequency Response", Section; Droop. Page 5 In your Interconnection, a generator tripped that was large enough to reduce the frequency from 60.00 Hz to 59.94 Hz. Your Balancing Authority's Frequency Bias is -200 MW/0.1 Hz. How many MW would your system initially contribute to frequency support? 200 MW 120 MW 100 MW 80 MW correct answer 120 MW.
in proportion to its MW rating allowing many generators on governor control to respond in parallel. EPRI Chapter 4: Frequency Control What is the most common cause of frequency fluctuations? System generation and load imbalance Market activity Power losses Load shed correct answer System generation and load imbalance Frequency of the Interconnection is determined by the total Interconnection load and total Interconnection generation. Any mismatch of load and generation will result in the Interconnection frequency deviating from the scheduled frequency. To conform to the CPS requirement, a Balancing Authority must have a _______. CPS1 greater than or equal to 200%. CPS1 greater than or equal to 100%. CPS1 greater than or equal to 90%. CPS1 less than or equal to 90%. correct answer CPS1 greater than or equal to 100%. To conform to the CPS requirement, a Balancing Authority must have a CPS1 greater than or equal to 100%. NERC Standard BAL-001, Measure M
Which of the following conditions describes a case where a Balancing Authority is hindering the Interconnection scheduled frequency? ACE is positive while frequency is 60.00 Hz ACE is positive while frequency is below 60.00 Hz ACE is negative while frequency is below 60.00 Hz ACE is negative while frequency is above 60.00 Hz correct answer ACE is negative while frequency is below 60.00 Hz Anytime the ACE of Balancing Authority is the same sign as the frequency error, the BA is considered as hindering the Interconnection and CPS1 scores will be affected negatively. 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. correct 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
Increase Generation correct 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. correct 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 correct 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 correct 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?
- Frequency of the Islands are matched
- Load is balanced for the two areas
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 correct 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. correct 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 correct 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
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. When a system is in an island, how much load needs to be shed to compensate for a 1 Hz deviation in frequency? 3 to 5 % 10 to 12 % 6 to 10 % 1 to 2 % correct answer 6 to 10 %. EOP-011 requires Balancing Authorities and Transmission Operators to develop Operating Plans, that include load shed. The NERC Electric System Restoration Reference Document states, "In an islanded area, generation and load should be adjusted in small increments to minimize the impact on frequency. As a rule, shed six to ten percent (6-10%) of load to restore the frequency approximately 1 Hz."
When a Balancing Authority has exhausted options and can no longer provide its customers' expected energy requirements, what can be used to obtain needed capacity and energy? Energy Emergency Alerts Demand Alert Imbalance Event Capacity Warning correct answer Energy Emergency Alerts. EOP-011 Emergency Operations, Energy Emergency Alert (EEA) process. If a circuit breaker does not have a synch-check, reclosing relay and has a large standing phase angle across it, how can the system operator know if it is safe to close the breaker avoiding shock torque to the neighboring generators? If the voltage is within +/- 10 % it is OK to close the breaker. Obtain help from the Regional operating committee engineers to advise you. Ask the generator operators to change reactive to a leading power factor and then check the frequency. Use the synchroscope in the substation control room as a guide to show you how to adjust the system to improve the phase angle. correct answer Use the synchroscope in the substation control room as a guide to show you how to adjust the system to improve the phase angle.
Isolate the load. Contact the Regional Reliability Organization. correct answer Isolate the load. EOP-005, System Restoration - Each Transmission Operator shall have a restoration plan approved by its Reliability Coordinator. The restoration plan shall allow for restoring the Transmission Operator's System following a Disturbance in which one or more areas of the Bulk Electric System (BES) shuts down... Prior to energizing an area that has been blacked out, the load must be isolated so that restoration can proceed in a controlled manner where load is restored in increments to stabilize frequency and voltage as the restoration proceeds. A Balancing Authority informs the Reliability Coordinator that the projected load in a Balancing Area for the next four 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. Which Energy Emergency Alert (EEA) level should the RC declare? EEA 3 EEA 1 EEA 2 No EEA should be declared until load shed is expected. correct answer EEA 1. EOP-011 Emergency Operations, Attachment 1, Energy Emergency Alerts - Level 1 is when the Balancing Authority is experiencing conditions where all available generation resources are committed to meet firm Load, firm transactions, and reserve
commitments, and is concerned about sustaining its required Contingency Reserves. Which type of emergency condition is due to not being able to meet the load requirements of an entities retail customers? Load Shed Capacity Emergency System Operating Limit Energy Emergency correct answer Energy Emergency. When synchronizing sections of the transmission system that have separated or islanded, frequency and voltage magnitude on each side of the breaker and the power angle across the breaker must be within proper limits. To bring these values within proper limits, the system operator should _____________________. Adjust the power angle on one side of the breaker to 90 degrees. Open additional lines until the voltage is matched. Adjust generator MW and MVAR output in one of the areas. Adjust the tap changer on the nearest transformer. correct answer Adjust generator MW and MVAR output in one of the areas. EPRI 2.5.7 Power flows from areas of more positive to less positive voltage angles, and reactive power flows from areas of higher voltage to areas of lower voltage. Therefore, to minimize flows across the breaker as it is being closed, these values must be within acceptable ranges on each side of the breaker before
A condition when a Load-Serving Entity has exhausted all other options and can no longer provide its customers' expected energy requirements is referred to as ____________? Energy deficiency Energy shortage Load shortage Energy Emergency correct answer Energy Emergency. A condition when a Load-Serving Entity has exhausted all other options and can no longer provide its customers' expected energy requirements. - NERC Glossary of Terms Used in Reliability Standards Early in the day, a BA with several units offline anticipates a capacity shortage during the afternoon. What should the BA consider first? Postpone or cancel unit maintenance where practical. Curtail demand side management customers immediately. Drop load immediately. Implement voltage reduction procedures immediately. correct answer Postpone or cancel unit maintenance where practical. A Balancing Authority anticipating an operating capacity or energy emergency shall perform actions in their Operating Plan which should include, bringing on all available generation, postponing equipment maintenance, scheduling interchange purchases in advance, and being prepared to reduce firm load.
Which of the following best describes the Load/Frequency Relationship? As frequency increases, load decreases. Load magnitude varies with system frequency. Only non-motor loads are affected by a change in system frequency. Load magnitude is independent of the system frequency. correct answer Load magnitude varies with system frequency. As a rule of thumb, a 1% drop in frequency will result in a 2% drop in load. - EPRI Power System Tutorial A Balancing Area's ACE is -40 MW at 1525 hours when the Balancing Authority loses 800 MW of generation. Initial governor action arrests frequency decay and shows the BA's ACE is now - 852 MW. At 1542 hours, the BA's ACE is -42 MW and the system frequency is 60.001 Hz. Assuming this event meets the Disturbance Control Standard (DCS) reporting criteria, what other actions is the BA required to take? The BA must over generate for the hour to minimize inadvertent The BA must notify the RC that Energy Emergency Alert is required to return ACE to ZERO. No further system operating action is required.
