1. November 12, 2010 Regional Planning Group Long-Term System Assessment Project Update Warren Lasher Manager, Long-Term Planning and Policy Jonathan Rose Planning Engineer

2. 2 Regional Planning GroupNovember 12, 2010 Purpose of the Long-Term Plan To Inform Near-Term Planning with Potential Solutions that Meet Long-Range System Needs Intent is not to select new circuits to recommend Rather, the intent is to provide a selection of alternatives through scenario analysis that can be considered when developing solutions for near-term congestion or reliability needs To meet the NERC TPL Requirements for development of 10-year transmission plan

3. 3 Regional Planning GroupNovember 12, 2010 Specific Focus The focus of this study is to look for: Long-Lead-Time Projects – projects that may require 5 or more years to bring on-line Large Projects – short-term analyses tend to focus on short-term solutions. A long-term perspective can indicate larger projects that both solve short-term issues but also meet long-term system needs more cost-effectively. This analysis will also provide implementation experience for some of the new tools and processes being developed for long-term planning.

4. 4 Regional Planning GroupNovember 12, 2010 Scope Study Years: 2020 – 2030 Load growth based on extrapolating current ERCOT Long-Term Load Forecast 2020 Peak Load: ~86,500 MW 2030 Peak Load: ~102,000 MW All generation currently on-line (and expected to maintain operation) plus all units with signed IAs as of 9/1/2010 Generation Expansion by Scenario Report will be submitted to PUCT by end of 2010

5. 5 Regional Planning GroupNovember 12, 2010 Methodology First Step: Simplify the ERCOT Transmission Network

6. 6 Motivation LTSA and DOE project are long-range studies. Due to uncertainties over a long time scale, different focus from near-term planning: –Scenario-based rather than typical year –Simplified model to highlight long-term concerns while de-emphasizing issues better dealt with as they arise in the near-term. November 12, 2010Regional Planning Group

7. 7 Example: A 2030 Load-Flow Case Starting from the latest ERCOT five-year planning case Increase loads from 70+GW to ~102 GW For initial testing purposes, add proxy generators to fulfill load at existing sites and other obvious transmission locations Resulting case has 1400 N-1 overloads. Why? Twenty years of transmission upgrades have not been modeled. November 12, 2010Regional Planning Group

8. 8 Example of 2030 Case Such a high number of overloads is prohibitively large to examine manually. Case simplification helps “filter” the overloads. Many overloads are on easily upgradable lines (generally short 69 kV). These aren’t the study’s focus, thus should be hidden from view. November 12, 2010Regional Planning Group

9. 9 Case Simplification Steps Process Code written by Dave Matthews (AEP) and Jonathan Rose (ERCOT) Remove 69-kV network. Remove 138-kV radial buses. Remove 138-kV inline buses. Raise rating of “short” rural lines. –Definition of “short” is subject to tuning. November 12, 2010Regional Planning Group

10. 10 Remove 69-kV Network Move all generators to nearest 138-kV bus. –POI bus is also moved, so bus number and name are preserved for recognition. “Move loads”: Measure flow at the 138 / 69 kV autos and represent these flows by loads at the 138-kV buses. Remove 69-kV network. November 12, 2010Regional Planning Group

11. 11 Remove Radials and Inlines Move load and switched shunts to neighboring bus. Three-winding transformers with a radial leg are converted to two-winding transformers. Radial load and switched shunt moved to high side. November 12, 2010Regional Planning Group

12. 12 After Simplification Bus count reduced 6000  2000 (approx) Line count reduced 6000  2000 (approx) Flows on 138-kV and 345-kV bulk transmission network mostly unchanged. Example simplified system will be posted on the Planning and Operations web-site November 12, 2010Regional Planning Group

13. 13 Regional Planning GroupNovember 12, 2010 Methodology Next Steps: Generation Expansion Analysis –Scenarios being evaluated: Business as Usual Coal Generation Expansion Gas Generation Expansion High Renewables Evaluate transmission projects that meet system needs

14. 14 Regional Planning GroupNovember 12, 2010 Summary Study focus is on identification of long-lead-time projects through scenario analysis that can be considered when developing solutions for near-term congestion or reliability needs Designed to meet the NERC TPL Requirements for development of 10-year transmission plan This analysis will provide implementation experience for some of the new tools and processes being developed for long-term planning.

15. 15 Regional Planning GroupNovember 12, 2010 Questions?