June 19, 2009 RPG Meeting ERCOT System Development Update Jeff Billo

2 RPG MeetingJune 19, 2009 RPG Project Review Update Recommendation Letter in process for: –AEPSC Abilene to San Angelo Project (Tier 2) The following projects were reclassified as Tier 4: –LCRA TSC Cushman-Highway 123 Project –LCRA TSC GPI-FM482-Parkway Project ERCOT Independent Review nearly complete for: –Austin Energy Decker to Techridge 138 kV Circuit Relocation Project (Tier 2) ERCOT Independent Review in process for: –Centerpoint 2012 Northwest Houston Reliability Project (Tier 2) –AEPSC Corpus Christi Improvements (Tier 1)

3 RPG MeetingJune 19, 2009 RPG Project Review Update Other projects under review –Oncor Lamesa Area Upgrades (Tier 1) –Oncor Comanche Peak 3 and 4 Additions Project (Tier 1) –Sharyland ERCOT Southeast Loop (Tier 1)

4 RPG MeetingJune 19, 2009 LCRA TSC GPI-FM 482-Parkway Project LCRA TSC/ New Braunfels Utilities Project to connect a new load-serving 138-kV substation, FM 482 Initially classified as Tier 2 due to new ROW transmission line connecting two existing substations ERCOT reviewed the proposal to ensure that it did not cause any congestion and to address comments in regards to the conductor size and proper termination substation

5 RPG MeetingJune 19, 2009 LCRA TSC GPI-FM 482-Parkway Project ERCOT analysis: –Does the project cause additional congestion? The project was added to the 2007 Five-Year Transmission Plan 2012 UPLAN model and no significant congestion difference was found between the benchmark and upgraded cases –Is Parkway or Weiderstein the better termination substation for the line? Both alternatives were studied in the 2007 Five-Year Transmission Plan 2012 UPLAN model and no significant congestion difference was found between the alternate cases The option of terminating the line into Parkway was approximately $1 million more than Weiderstein With the line terminated into Parkway compared to the line terminating into Weiderstein the post-contingency* loading on the Schertz-Parkway 138-kV line was 16% lower [*contingency = Marion-Hill Country/ Skyline 345-kV double circuit] Due to past congestion on Cibolo-Schertz-Parkway ERCOT agreed with LCRA TSC’s proposal to terminate the line into the Parkway substation

6 RPG MeetingJune 19, 2009 LCRA TSC GPI-FM 482-Parkway Project ERCOT analysis: –Is 220 MVA large enough for the GPI-FM 482-Parkway line? The line was modeled without load at FM 482 in the following UPLAN models: –2007 Five-Year Transmission Plan final 2012 case –2009 Five-Year Transmission Plan preliminary 2014 case Security Constrained Economic Dispatch was run for all hours in the year for both cases The highest base case (n-0) loading on the line was found to be 114 MW. For this time, the highest contingency loading was found to be 167 MW (76%) for the contingency loss of Marion-Hill Country/ Skyline 345-kV double circuit Ran transfer analysis in MUST on the SSWG 2013 summer peak case updated in March For North to San Antonio transfer a significant number of other elements overloaded before GPI-FM 482-Parkway Did not see evidence for a larger capacity conductor

7 RPG MeetingJune 19, 2009 LCRA TSC GPI-FM 482-Parkway Project ERCOT analysis did not see any additional congestion caused by GPI- FM 482-Parkway and agreed with LCRA TSC’s recommendation to terminate the line at Parkway with a conductor rating of 220 MVA Since the project need was based on LCRA TSC and New Braunfels Utilities requirements for serving load and not based on NERC or ERCOT criteria violations, the project was reclassified as Tier 4 pursuant to the ERCOT Regional Planning Group Charter and Procedures Section 2.3.2

8 RPG MeetingJune 19, 2009 Questions?