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Comparing Load Profiles: Art or Science?

Comparing Load Profiles: Art or Science?. Roberta Laccetti National Grid 2005 AEIC Load Research Conference July 11, 2005. Question:. Do class load shapes vary by… State? Utility? Supplier? Transmission Congestion Zone? Year?. Answer:. Yes. No. It depends on why you’re asking.

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Comparing Load Profiles: Art or Science?

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  1. Comparing Load Profiles:Art or Science? Roberta Laccetti National Grid 2005 AEIC Load Research Conference July 11, 2005

  2. Question: • Do class load shapes vary by… • State? • Utility? • Supplier? • Transmission Congestion Zone? • Year?

  3. Answer: • Yes. • No. • It depends on why you’re asking.

  4. Real Questions: • Can we use MA samples to represent NH rate classes in COS filings? • Can we ignore one company’s samples after merger? • Do residential customer load shapes vary between utilities in MA? • Do we need to update our load shapes every year?

  5. Approaches to Comparing Load Shapes • Traditional Load Research Statistics • Visual Comparisons of Graphs • Normalized or Unitized • All, Average, or Specific Days • Accounting for Errors in Estimated Loads • Some Statistical Summaries

  6. Question #1: Can we use MA samples to represent NH rate classes? • Number of customers served in NH is less than 40,000. • Cost of Load Research relative to revenues is high. • MA is geographically close and good transfer methods can be used. • But… • Regulators are unique • Rate class definitions differ • Appliance saturation varies

  7. Average Residential Load Shapes: MA/NH

  8. Average Residential Load Shapes: MA/NH

  9. Average Residential Load Shapes: MA/NH

  10. Average Residential Load Shapes: MA/NH Peak Day with Error Bounds

  11. Average Residential Load Shapes: MA/NH Some Summary Statistics • Mean Bias Error: • -0.02 • Root Mean Squared Error: • .11 • Coefficient of Variation of the Root Mean Squared Error: • .13

  12. Question #1: Can we use MA samples to represent NH rate classes? • Answer #1: No. • Ordered by the commission.

  13. Question #2: Can we ignore one company’s samples after merger? • EUA/NEES merger resulted in rate consolidation. • Continuous and comprehensive samples existed in each company, doubling sample sizes. • Metering differences required two reading systems. • But… • Regulators may want to evaluate impacts of consolidated rates on customers, by company. • Using one company’s samples to represent entire territory may produce biased results.

  14. Medium C&I Load Shapes: NEES vs. EUA Unitized Average Day - August 2001

  15. Unitized Average Day Load Shapes: NEES/CombinedPercent Differences

  16. Question #2: Can we ignore one company’s samples after merger? • Answer #2: No. • NEES-only samples would produce biased estimates of merged company classes. • Keep collecting data from both samples until new samples are implemented. • Convince Meter Services group that the quicker they install new samples, the sooner they can stop using old collection system.

  17. Question #3: Do residential customer load shapes vary between utilities in MA? • Regulatory debate about Default Service pricing for customers with no competitive supply options. • We recommend a single price for utility-provided service in each load zone. • One Distribution Co. claimed differences in load profiles preclude a state-wide approach.

  18. Comparison of Average Residential Load Shape:MA Utilities – Normalized 2002

  19. Question #3: Do residential customer load shapes vary between utilities in MA? • Answer #3: No. • Supports company recommendations on auction and pricing.

  20. Question #4: Do we need to update our load shapes every year? • Cost-cutting in Operations area has been severe. • No regulatory requirement in NY. • Wide range of practices in other companies. • But… • Load shapes are used for commodity pricing • Load shapes support estimation of competitive supplier load and ICAP.

  21. Comparison of 2003/2002 Load Shapes:Impacts on Pricing • Transfer methods considered: • Calendar Mapping • Day-Type Mapping • Weather Normalization

  22. Comparison of 2003/2002 Load Shapes:Results • Load estimation for pricing and settlement: • Calendar mapping: • Load-weighted annual price = 1% below actual • Weather model with 5 day-types and 4 seasons: • Load-weighted annual price = .01% below actual • Peak hour estimate (ICAP): • Calendar mapping: • Estimate of class demand = 1.9-29.7% below actual • Prior year’s peak day (at peak hour): • Estimate of class demand = 6.1% below to 20.4% above actual

  23. Question #4: Do we need to update our load shapes every year? • Answer #4: Maybe. • National Grid NE practices. • Risk of criticism by market players. • Timing of next rate case.

  24. Summary • There are many different ways to compare class average load shapes. • Conclusions about similarities and differences should be based on how the shape will be used. • The answer may be, “It depends…”

  25. Extra Credit Question:What is causing spikes in Residential Class precision levels?

  26. Clue

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