SOPD Load Forecasting & Energy Scheduling 4 — Questions and Answers
Question 1: Which forecasting approach uses historical load data from similar days to predict future load?
- Analog day method (Correct answer)
- Fourier transform method
- Linear programming extrapolation
- Kalman filter prediction
Correct answer: Analog day method
The analog day method identifies historical days with similar weather, calendar, and economic conditions and uses their actual load profiles to predict upcoming demand.
Question 2: Pumped storage hydro scheduling is typically optimized by:
- Running pumps during high-load periods and generating during low-load periods
- Pumping during off-peak low-cost periods and generating during peak high-value periods (Correct answer)
- Scheduling pumping and generation randomly to balance reservoir levels
- Using pumped storage exclusively for frequency regulation
Correct answer: Pumping during off-peak low-cost periods and generating during peak high-value periods
Pumped storage is optimized by pumping when energy is cheap (off-peak) and generating when energy is expensive (peak), capturing the price spread as economic value.
Question 3: A system operator's load forecast shows a duck curve pattern. This means:
- Load is expected to peak at midnight due to industrial demand
- Net load dips midday due to solar generation then ramps steeply in the evening (Correct answer)
- Demand response programs will reduce morning load by 30%
- Transmission constraints will limit imports during peak hours
Correct answer: Net load dips midday due to solar generation then ramps steeply in the evening
The duck curve describes net load (total load minus solar) that dips deeply midday as solar output peaks, then ramps steeply as solar drops and evening demand rises.
Question 4: Which resource is MOST appropriate to address a rapid 15-minute load ramp identified in a short-term forecast?
- Nuclear baseload units already at maximum output
- Fast-ramping combustion turbines or demand response resources (Correct answer)
- Large coal units with slow ramp rates
- Transmission line switching to reduce load
Correct answer: Fast-ramping combustion turbines or demand response resources
Fast-ramping resources such as gas combustion turbines or demand response can respond within minutes, making them ideal for covering rapid load changes.
Question 5: When calculating load responsibility for a capacity planning study, an operator includes:
- Only peak load from the current operating hour
- Coincident peak load plus a planning reserve margin (Correct answer)
- Average annual load multiplied by 8,760 hours
- Only load served directly by company-owned generation
Correct answer: Coincident peak load plus a planning reserve margin
Capacity planning uses coincident peak load plus a reserve margin (typically 15-20%) to ensure adequate resources are available under stressed conditions.
Question 6: A long-term load forecast that accounts for increased electric vehicle adoption would MOST LIKELY show:
- Decreased evening peak demand as drivers charge during the day
- Increased off-peak demand and potential new late-evening demand peaks (Correct answer)
- Flat load growth with no change in peak timing
- Reduced total energy consumption due to EV efficiency
Correct answer: Increased off-peak demand and potential new late-evening demand peaks
Mass EV adoption typically increases off-peak overnight charging load and may create new demand peaks in the evening when drivers return home and plug in.
Question 7: In a security-constrained economic dispatch (SCED), the 'security constraint' refers to:
- Cybersecurity requirements for SCADA systems
- Transmission line and equipment limits that cannot be violated even during economic optimization (Correct answer)
- Generator fuel supply contracts limiting output
- Reserve margin requirements set by NERC standards
Correct answer: Transmission line and equipment limits that cannot be violated even during economic optimization
Security constraints are transmission and equipment thermal and voltage limits that the economic dispatch solution must respect, ensuring the dispatch is both optimal and secure.
SOPD Load Forecasting & Energy Scheduling 4
Which forecasting approach uses historical load data from similar days to predict future load?