1. Kirk Schneider American Electric Power Tulsa, Oklahoma AEIC Annual Load Research Conference Reno, Nevada September 10-13, 2006 System Load Calculation for AEP-Texas

2. What We Did Why We Did It How We Did It What We Found So What? Introduction

3. The American Electric Power System

4. ERCOT became single Control Area 7/31/01 Companies stopped checking tie lines. Installed IDRs on a Number of Tie-Lines Verified IDR Data for generation and tie-lines Rate filing for TCC and TNC later this year. Update loss studies. Update demand studies What We Did

5. What is System Load? Total power consumption on system Measure Power Received from Generators Measure Power Flow at Interconnect Points Can directly measure load, but not losses

6. “Top-Down” System Load Calculation Generation: 300 + 200 Interchange:-10 -20 +40 -------- Net Load: 510 MW

7. “Bottom-Up” Load Calculation Load: RES 190 COM + 100 IND + 60 WHL + 140 Losses: + 30 ------------------ Load: 520 MW UFE: - 10 MW

8. Power Consumption in North American Grid No Boundary Metering Power is consumed the instant it is generated Power Consumed = Power Generated Power Consumed = Power used + power “lost”

9. ERCOT Transmission System

10. ERCOT System Load Connected to grid with 3 DC ties System Load = generation + power imported over DC ties – power exported over DC ties SYSTEM LOAD = GENERATION – NET INTERCHANGE EPS Meters on Generation and DC Ties

11. AEP-Texas System Load Texas Central Co. (South Texas) Texas North Co. (West Texas) TCC ~ 30 Gens, 50 Interconnects TNC ~ 20 Gens, 40 Interconnects

12. Texas Central Transmission System

13. Texas North Transmission System

14. Demand Studies Σ Sales * Loss Factor = Estimated System Load Loss Studies Losses = System Load – Σ Sales Transmission Settlements Unbilled Sales Checks and Balances All Assume System Load is Correct Why AEP Needs System Load

15. About 12 complete – meter and CT / PTs About 24 meter only using existing CT / PTs Accuracy of Meters Leveraging Existing Metering In South Texas How did We Implement AEP-Texas Tie-Line Metering?

16. TCC Ties to South Texas EC

17. How Are We Collecting and Analyzing the Data? Collecting Data Using MV-90 System Data Validation Analyzing Data Using SAS Sent to CEAS System

18. PROBLEMS! Gaps in IDR Data Suspicious Looking Data Missing Meters Problems Getting Data from ERCOT

19. SCADA to the Rescue! PI Database Installed Oct 2004 Analog Measurements Accessible with ODBC or OLE SAS Table Containing SCADA Data

20. Data Validation Use SCADA Data to Validate IDR Data SCADA Strengths Complement IDR Data Use SCADA Data to Fill IDR Data Gaps Examples

21. Everything’s All Right – Generator 1

22. Everything’s All Right – Generator 2

23. Everything’s All Right – Tie 1

24. Everything’s All Right – Tie 2

25. Good Enough – SCADA at opposite end of line

26. Better than Nothing – SCADA at opposite end, load along line

27. Load Outside Boundary of Meters

28. Gap In IDR Data - Generator

29. Gap in IDR Data - Line

30. SCADA Goes “Flat-Line” for Short Period – Gen

31. SCADA Goes “Flat-Line” for Short Period – Line 1

32. SCADA Goes “Flat-Line” for Short Period – Line 2

33. SCADA Goes “Flat-Line” for Short Period – Line 3

34. SCADA Goes “Flat-Line” for Long Period – Line 1

35. SCADA Goes “Flat-Line” for Long Period – Line 2

36. SCADA Goes “Flat-Line” – Long Period - Gen

37. SCADA Resolution Problem – Small Line

38. SCADA Resolution Problem – Line

39. Time-Synch or Resolution??

40. No SCADA Available – Wholesale POD’s

41. General SCADA Failure – Example 1 Gen

42. General SCADA Failure – Example 2 Gen

43. General SCADA Failure – Example 3 Line

44. General SCADA Failure – Example 4

45. General SCADA Failure – Example 5 Line

46. Suspicious Generator Data

47. Impact on System Load Calc

48. Meter Configuration

49. Using Alternate SCADA Points

50. IDR Data vs. SCADA IDR Strengths True integrated values Distributed data collection Lower cost than SCADA SCADA Strengths Time synch extremely accurate Data available real-time Multiple backup measurements Together Provide Very Reliable, Accurate Data

51. Top Down vs. Bottom Up Summer

52. Top Down vs. Bottom Up Winter

53. Top Down System vs. Bottom Up At Meter

54. System Losses

55. Percent Losses

56. Summary of Results SCADA Bailed Us Out Strengths of IDR Data and SCADA Complementary Customer Load Aggregation Matches System Load Able to Perform Loss Study

57. So What? We Can Measure AEP-Texas System Load Two Measurements Better Than One Understand Your System Load Data Accurate System Load = $$$ Let’s Work Together Again!