SOPD Emergency Procedures 4 — Questions and Answers
Question 1: What is the primary purpose of Under-Frequency Load Shedding (UFLS) relay schemes?
- To automatically shed load in steps to arrest frequency decline and prevent total system collapse (Correct answer)
- To protect individual generators from operating below rated speed
- To signal the reliability coordinator when frequency falls below 59.95 Hz
- To transfer load from heavily loaded feeders to lightly loaded ones
Correct answer: To automatically shed load in steps to arrest frequency decline and prevent total system collapse
UFLS schemes automatically trip distribution feeders in pre-programmed steps to remove enough load so that remaining generation can stabilize system frequency.
Question 2: During a cyber security incident affecting the energy management system (EMS), what is the operator's FIRST action?
- Switch to manual operations using backup procedures while notifying the security team (Correct answer)
- Shut down all SCADA communications immediately to isolate the attack
- Reboot the EMS servers to clear any malware
- Wait for the IT department to assess the situation before changing operations
Correct answer: Switch to manual operations using backup procedures while notifying the security team
Switching to manual operations ensures continued grid control while the cybersecurity incident is investigated, as shutting down SCADA could leave operators blind.
Question 3: What does 'N-1 contingency' mean in the context of emergency planning?
- The system must remain stable and within limits after the loss of any single element (Correct answer)
- The system has one backup generator for every operating generator
- Emergency procedures must be rehearsed at least once per year
- One operator must always be on duty during high-risk periods
Correct answer: The system must remain stable and within limits after the loss of any single element
The N-1 criterion requires that the bulk power system remain operable and within reliability limits following the sudden loss of any single element.
Question 4: A neighboring balancing authority declares a 'Conservative Operations' alert. What does this require of your balancing area?
- Take conservative actions to reduce risk of cascading failures, even if not yet experiencing an emergency (Correct answer)
- Immediately begin load shedding in anticipation of generation loss
- Disconnect all scheduled interchange with the affected balancing authority
- Increase frequency response reserves to 200% of normal levels
Correct answer: Take conservative actions to reduce risk of cascading failures, even if not yet experiencing an emergency
NERC's Conservative Operations requirement directs operators to proactively reduce operational risk during deteriorating conditions, before an actual emergency occurs.
Question 5: If automatic generation control (AGC) fails during high-load conditions, what must operators do to maintain frequency control?
- Manually adjust generator outputs to maintain area control error (ACE) within acceptable limits (Correct answer)
- Switch all generators to isochronous control mode automatically
- Immediately notify customers to voluntarily reduce load
- Transfer balancing authority responsibilities to the reliability coordinator
Correct answer: Manually adjust generator outputs to maintain area control error (ACE) within acceptable limits
When AGC fails, operators must manually monitor ACE and direct generation adjustments to maintain frequency and meet interconnection obligations.
Question 6: Which of the following best describes a 'brownout' as distinguished from a 'blackout' in emergency power operations?
- A brownout is an intentional or unintentional voltage reduction while supply is maintained; a blackout is a complete loss of power (Correct answer)
- A brownout affects only residential customers while a blackout affects industrial customers
- A brownout is caused by equipment failure; a blackout is caused by operator error
- A brownout lasts less than one hour; a blackout lasts more than one hour
Correct answer: A brownout is an intentional or unintentional voltage reduction while supply is maintained; a blackout is a complete loss of power
A brownout involves reduced voltage across the system while power remains connected, whereas a blackout is a complete interruption of electrical supply.
Question 7: What is the purpose of 'system restoration drills' required by NERC EOP standards?
- To ensure operators are trained and practiced in executing restoration plans before an actual blackout occurs (Correct answer)
- To test protective relay settings under simulated fault conditions
- To satisfy FERC annual reporting requirements for transmission operators
- To verify that backup communication systems are operational
Correct answer: To ensure operators are trained and practiced in executing restoration plans before an actual blackout occurs
NERC EOP-005 requires restoration drills to verify that operators can correctly and efficiently execute blackout restoration procedures when an actual event occurs.
SOPD Emergency Procedures 4
What is the primary purpose of Under-Frequency Load Shedding (UFLS) relay schemes?