1. Generation to be Dispatched(GTBD) Analysis For the purpose of discussion only PDCWG/QMWG Joint Meeting 11/02/2012

2. 2 Discussion Points 1.Zonal/Nodal Regulation Deployment statistics 2.Regulation Deployment and Recall 3.Short-Term Load Forecast and Projected Load Ramp Rate (PLRR) 4.Analysis of Regulation Deployment (June 2012 to Aug 2012) 5.Discuss different GTBD calculation options including the one proposed by NPRR 486 6.Statistical Analysis of different methods of calculating GTBD with August and September data 7.Summary 7/9/2016For the purpose of discussion only

3. 3 Zonal/Nodal Regulation Deployment Statistics For the purpose of discussion only7/9/2016 Regulation-Up Deployed (5 min sample data) Regulation-Down Deployed (5 min sample data) Regulation-Up Deployed (hourly average data) Regulation-Down Deployed (hourly average data) Zonal Operation (Jan to Nov. 2010) 357.250-314.464284.776-234.374 Nodal Operation (Dec 2010 to Sept 2012 169.378-138.174124.176-89.236

4. 4 Regulation Deployment – Example 1 For the purpose of discussion only7/9/2016

5. 5 Regulation Deployment – Example 2 For the purpose of discussion only7/9/2016

6. 6 Short Term Load Forecast and PLRR For the purpose of discussion only7/9/2016

7. 7 Analysis of Regulation Deployment For the purpose of discussion only7/9/2016 Regulation Analysis Total Regulation- Up Duration Total Regulation- Down Duration Average Regulation-Up Deployed (MW) Average Regulation-Down Deployed (MW) June -1252.44%47.56%177.51-146.56 June-12 Peak Hour (14 to 18)64.17%35.83%184.96-118.37 July-1253.23%46.77%150.89-120.47 July - 12 Peak Hour (14 to 18)69.19%30.81%160.68-115.58 August-1259.20%40.80%162.37-116.85 August-12 Peak Hour (14 to 18)75.99%24.01%174.47-97.60

8. 8 Analysis of Regulation Deployment……..continued For the purpose of discussion only7/9/2016 Regulation Analysis Total Regulation- Up Duration Total Regulation- Down Duration Average Regulation-Up Deployed (MW) Average Regulation-Down Deployed (MW) September -12 53.99%46.01%169.90-128.64 September-12 Peak Hour (14 to 18) 64.87%35.13%159.61-119.00 October -12 47.47%52.53%138.36-126.78 October - 12 Peak Hour (14 to 18)48.74%51.26%129.90-106.85

9. 9 Underlying inputs for GTBD Calculation 1.Current GTBD Calculation Total Gen + 1.1*5 *Projected Load Ramp Rate (PLRR) 2.GTBD1 (proposed per NPRR-486) Total UDBP + Total Regulation Deployed + 1.1*5*PLRR 3.GTBD2 (modification includes using regulation-bias factor and modified K3) Total Gen + 1.2*5*PLRR +0.1*Regulation Deployed 4.GTBD3 (increased K3) Total Gen+1.3*5*PLRR For the purpose of discussion only7/9/2016

10. 10 Statistical evaluation of GTBD calculation For the purpose of discussion only7/9/2016 Aug & Sept all hours Current GTBDGTBD1GTBD2GTBD3 Mean3.07247.3487.0022.819 Standard Deviation 109.225207.099115.512127.401 Zero mean probability 0.4890.4100.4760.491 Aug & Sept (14- 18 hours) Current GTBDGTBD1GTBD2GTBD3 Mean7.18593.72712.1462.514 Standard Deviation 108.767165.778109.389118.145 Zero mean probability 0.4740.2860.4560.492

11. 11 Statistical evaluation of GTBD calculation….(continued) For the purpose of discussion only7/9/2016 Aug & Sept (0-4 hours) Current GTBDGTBD1GTBD2GTBD3 Mean -7.197-27.471-18.651 -27.040 Standard Deviation 91.378178.91395.113 98.297 Zero mean probability 0.5310.5610.5780.608 Aug & Sept (5-8 hours) Current GTBDGTBD1GTBD2GTBD3 Mean7.26129.77326.54538.180 Standard Deviation 114.002201.453119.175126.917 Zero mean probability 0.4750.4410.4120.382

12. 12 Statistical evaluation of GTBD calculation….(continued) For the purpose of discussion only7/9/2016 Aug & Sept (09- 13 hours) Current GTBDGTBD1GTBD2GTBD3 Mean26.642115.95459.66877.240 Standard Deviation 112.424217.447110.020116.149 Zero mean probability 0.4060.2970.2940.253 Aug & Sept (19- 23 hours) Current GTBDGTBD1GTBD2GTBD3 Mean-17.73921.112-40.936-69.951 Standard Deviation 113.653230.697116.169123.142 Zero mean probability 0.5620.4640.6380.715

13. 13 Summary & Suggestions 1.Slide showing Regulation-Analysis reflects small bias toward usage of Regulation-Up Service for all durations 2.Regulation usage duration from 14:00 to 18:00 hours is greatly biased towards the usage of Regulation-Up service 3.Statistical Analysis of GTBD-Load (Error) reflects, the current GTBD error is very close to the probability of zero mean of the error (which is 0.5 for normal distribution) 4.Statistical Analysis shows that the GTBD calculation proposed through NPRR 486, increases Standard deviation of error, increase the mean of average error and reduces the probability of zero mean error away from 0.5 compared to all other options. 5.ERCOT Suggests that changes in the GTBD calculation be made as reflected in GTBD2 calculation. Regulation contribution to GTBD be tuned with the weighing factor. The Regulation contribution should be a rolling average value. 6.ERCOT believes that Step 5, “Regulation Recall based on pending base-point” functionality and some LFC tuning will help improve the regulation bias issue. 7/9/2016For the purpose of discussion only

14. 14 Questions?? 7/9/2016For the purpose of discussion only