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Settlement Accuracy Analysis

This presentation discusses the use of advanced meters to improve load profiling accuracy by increasing meter reading frequency, facilitating larger load research samples, and enabling dynamic profiling. Analysis conducted by ERCOT reveals insights on meter reading frequency impact on profiling error. Results show improved accuracy with higher frequency readings. Various examples and reports demonstrate the benefits of increased meter reading frequency on load profiling error reduction.

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Settlement Accuracy Analysis

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  1. Settlement Accuracy Analysis Prepared by ERCOT Load Profiling

  2. Introduction and Methodology

  3. Settlement Accuracy Analysis • Advanced metering can be used to enable 15-minute interval settlement for all ESIIDs. • Alternatively, advanced metering can be used to: • Enable 15-minute interval settlement for some ESIIDs, and • Improve the accuracy of load profiling and settlement for all other ESIIDs • The intent of this presentation is to address the use of advanced meters to improve load profiling by: • Increasing the frequency of meter readings • Creating the feasibility for larger more frequently updated load research samples • Facilitating the introduction of new load profiles • Enabling dynamic (true/lagged) profiling

  4. Meter Reading Frequency • Currently monthly meter reads are used in settlement and are profiled using adjusted static models • Load profile models are structured in 3 stages • Stage 1: Monthly kWh - Daily kWh • Stage 2: Daily kWh - Hourly kWh • Stage 3: Hourly kWh – 15-minute interval kWh • Increasing the meter reading frequency can eliminate one or more stages from the profile model and the estimation error associated with the stages • Universal TOU meter reading (independent of pricing) could leverage the “chunking” functionality already existing in ERCOT systems to further reduce profiling error • TOU meter readings would individualize the profile shape to capture systematic difference in usage patterns across customers

  5. Meter Reading Frequency • ERCOT utilized the interval data from the Load Research Sample customers to investigate the profiling error impact associated with the levels of meter reading frequency. • ERCOT’s round 1 load research sample was approximately one-half the size anticipated to be needed • The models developed from the load research data are not as accurate as would be estimated from larger samples

  6. Meter Reading Frequency • ERCOT utilized the interval data from the Load Research Sample customers to investigate the impact of several levels of meter reading frequency on profiling error. • Analysis window: July 2005 - June 2006 • The meter reading frequency levels analyzed are listed below: Time PeriodApprox. # of Reads per month Monthly (calendar month) 1 TOU Monthly 8 Daily 28 TOU Daily 120 Hourly 720

  7. Meter Reading Frequency • Interval data for each of the sample customers was summed over the appropriate time periods to determine non-IDR meter readings for the various reading frequency levels • The non-IDR meter readings were then profiled following the currently established process • The actual interval values and the profiled versions of those intervals were then extrapolated to the profile class level using standard load research statistical methodology • The difference between the actual and profiled class level estimates is a measure of the amount of profiling error (at the class level) associated with the various meter reading frequency levels

  8. Meter Reading Frequency • For this analysis, profile specific TOU schedules were created to isolate periods with significant variation in load shape and high volume of consumption

  9. Example of Actual vs Profiled – Monthly ReadsBUSMEDLF – COAST - July 14, 2005

  10. Example of Actual vs Profiled – Monthly TOU ReadsBUSMEDLF – COAST - July 14, 2005

  11. Example ofActual vs Profiled – Daily Reads BUSMEDLF – COAST - July 14, 2005

  12. Example of Actual vs Profiled – Daily TOU ReadsBUSMEDLF – COAST - July 14, 2005

  13. Example ofActual vs Profiled – Hourly Reads BUSMEDLF – COAST - July 14, 2005

  14. Summary Reports - kWh

  15. Annual Average Interval kWh Difference Profile – Actual • Profiling spreads kWh from meter readings across intervals but does not change the total kWh use. • Consequently, the average difference between actual and profiled kWh is zero; differences shown above are attributable to rounding.

  16. Annual Average Interval Percent Difference Profile – Actual • Increased meter reading frequency results in improved annual average percent differences. • Across all profile types Busnodem improves the most – 1.38 % improvement from monthly to hourly reads • Residential profile types improve by 1.12% from monthly to hourly reads • All percent differences are positive – overestimation of low load intervals underestimation of high load intervals

  17. Meter Reading Frequency • All percent differences are positive – overestimation of low load intervals underestimation of high load intervals • An inherent limitation of adjusted static models because the estimation of model coefficients is driven by the preponderance of medium load intervals • The load profiling process allocates kWh from meter readings across all intervals in the period; overestimated intervals must be offset by underestimated intervals The following slides illustrate the over/under estimation for selected profile models

  18. Average Day Across the Study Period RESHIWR - COAST underestimating overestimating

  19. Average Day Across the Study Period RESHIWR - NCENT underestimating overestimating

  20. Average Day Across the Study PeriodBUSMEDLF - COAST underestimating overestimating

  21. Average Day Across the Study Period BUSMEDLF - NCENT underestimating overestimating

  22. Distribution of Interval Percent Differences BUSMEDLF Increasing meter reading frequency results in tighter distribution of differences Percent Difference (Profile – Actual)

  23. Distribution of Interval Percent Differences RESHIWR Increasing meter reading frequency results in tighter distribution of differences Percent Difference (Profile – Actual)

  24. Summary Reports - Dollars

  25. Annual Average Absolute Interval Percent Difference Profile – Actual • Increased meter reading frequency results in improved annual average absolute interval percent differences. • Buslolf, Busnodem, Reshiwr, and Reslowr all improve by about 5 % going from monthly to hourly reads • Bushilf and Busmedlf improve by 1.6% and 2.8% respectively

  26. Annual Total Dollar Difference Profile – Actual Annual Dollars = ∑i kWhi * MCPEi • Annual total dollar differences are relatively small even with monthly reads • The differences range from $0.39 for Busnodem up to $21 for Bushilf per month • Residential profiles account for ~ 60% of annual dollars and have a difference of about $1.70 per month • Increased meter reading frequency results in lower annual total dollar differences. • In general dollar differences are negative • Overestimation of low load intervals and underestimation of high load intervals • Positive correlation between load and MCPE

  27. Average Day Across the Study PeriodRESHIWR - COAST

  28. Average Day Across the Study PeriodRESHIWR - NCENT

  29. Average Day Across the Study PeriodBUSMEDLF - COAST

  30. Average Day Across the Study Period BUSMEDLF - NCENT

  31. Selected Weekly Profiles BUSMEDLF_NCENTRESHIWR_NCENT

  32. Summer Week – August 15-21, 2005 BUSMEDLF - NCENT

  33. Summer Weekday – Thursday, August 18, 2005 BUSMEDLF - NCENT

  34. Summer Weekend – August 20-21, 2005 BUSMEDLF - NCENT

  35. Fall Week – October 17-23, 2005 BUSMEDLF - NCENT

  36. Fall Weekday – Friday, October 21, 2005 BUSMEDLF - NCENT

  37. Fall Weekend – October 22-23, 2005 BUSMEDLF - NCENT

  38. Winter Week – February 13-19, 2006 BUSMEDLF - NCENT

  39. Winter Weekday – Friday, February 17, 2006 BUSMEDLF - NCENT

  40. Winter Weekend – February 18-19, 2006 BUSMEDLF - NCENT

  41. Spring Week – March 27 - April 2, 2006 BUSMEDLF - NCENT

  42. Spring Weekday – Tuesday, March 28, 2006 BUSMEDLF - NCENT

  43. Spring Weekend – April 1-2, 2006 BUSMEDLF - NCENT

  44. Summer Week – August 15-21, 2005 RESHIWR - NCENT

  45. Summer Weekday – Monday, August 15, 2005 RESHIWR - NCENT

  46. Summer Weekend – August 20-21, 2005 RESHIWR - NCENT

  47. Fall Week – October 17-23, 2005 RESHIWR - NCENT

  48. Fall Weekdays – Thursday-Friday, October 20-21, 2005 RESHIWR - NCENT

  49. Fall Weekend – October 22-23, 2005 RESHIWR - NCENT

  50. Winter Week – February 13-19, 2006 RESHIWR - NCENT

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