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
% Difference
Annual Use
7,912 kWh
8,034 kWh
+ 1.5%
CP Demand (4pm on Mon, 8/30/04)
1.54 kW
1.50 kW
- 2.6%
12-CP Demand
1.44 kW
1.13 kW
- 21.5%
Class Pk Demand
1.93 kW (7pm on Mon, 12/20/04)
2.07 kW (7pm on Sun, 1/25/04)
- 7.2%
Load Factor
46.5%
44.5%
- 4.3%

8. Average Residential Load Shapes: MA/NH
MA= green, NH = blue

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/Combined Percent Differences
Residential
Small C&I
Medium C&I
January
-5.1% to 0.0%
-2.3% to 0.7%
-0.3% to 5.2%
April
-6.2% to 0.1%
-4.1% to 1.1%
-0.4% to 5.9%
August
-2.0% to 0.8%
-3.0% to 0.5%
-2.5% to 3.3%

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):
Estimate of class demand = % 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