3/28/2008 RPG CREZ Meeting CREZ Transmission Optimization (CTO) Study And The Oscar Goes To… Warren Lasher Manager, System Assessment

2 RPG CREZ Meeting3/28/2008 Designated Zones and Scenario Wind Levels Capacity of New CREZ Wind by Scenario (MW) Wind Zone Scen. 1Scen. 2Scen. 3Scen. 4 Panhandle A 1,4223,1914,9606,660 Panhandle B 1,0672,3933,7200 McCamey 8291,8592,8903,190 Central 1,3583,0474,7355,615 Central West 4741,0631,6512,051 Total * 12,05318,45624,85924,419 * Assumes 6,903 MW of existing wind capacity

3 RPG CREZ Meeting3/28/2008 Study Approach Develop a number of significantly different core concepts and test their performance Variations on the concepts with best performance will be developed and tested The best performing plan will be selected for the scenario Scenario 2 Range of Potential Solutions Significantly-Different Plans, e.g.

4 RPG CREZ Meeting3/28/2008 High-level Concepts under study include: 1)Incremental 345-kV transmission system for wind in west Texas 2)Integrated 345-kV transmission system for wind in west Texas 3)Reduced number of right-of-ways using higher voltage circuits (500 kV or 765 kV) 4)Low impedance backbone or loop 5)HVDC circuit(s) to move power to load centers or between load centers, integrated with 345-kV upgrades Concepts

5 RPG CREZ Meeting3/28/2008 Recommended Plan Optimized for each Scenario Optimized for Scenario 1 Optimized for Scenario 2 Optimized for Scenario 3 Optimized for Scenario 4 12 GW18 GW25 GW24 GW

6 RPG CREZ Meeting3/28/2008 Staging and Expansion Will develop a preferred plan that is optimized for each of the four scenarios Will provide expansion path of what elements in each of these plans should be built first if that Scenario is selected (except for Scenario 1) –Use lower scenarios as basis Will develop an expansion path from the preferred plan for the lower scenarios, so as to allow for consideration of future expandability of those plans –Using next higher scenario as basis

7 RPG CREZ Meeting3/28/2008 Staging and Expandability Optimized for Scenario 1 Optimized for Scenario 2 Optimized for Scenario 3 Optimized for Scenario 4 12 GW18 GW25 GW24 GW

8 RPG CREZ Meeting3/28/2008 Where We Are Numerous plans have been developed, modified, improved, discarded, rethought, combined, pirated, and hybridized Many plans have been evaluated using SCUC-ED model for wind curtailment and evaluated using AC contingency analysis Final plans for scenarios 1 and 2 have been evaluated for dynamic stability The report is almost complete Maps are being ed…

9 RPG CREZ Meeting3/28/2008 What Have We Learned? DFW SA A primary consideration in the design of these plans has been the fact that the Dallas/Fort Worth area is the closest load center to much of the CREZ wind 5,600 MW2,600 MW10,300 MW HGA Wind Capacity for Scenario 2 (CREZ wind and existing wind)

10 RPG CREZ Meeting3/28/2008 What Have We Learned? A fundamental question in this study: –What transmission plan is best suited to collect wind generation from scattered locations across much of west Texas, move it hundreds of miles to east Texas, and then redistribute the power-flows to load centers, utilizing available transmission capacity but without causing significant congestion on the existing transmission system? Answer: It depends –On the distribution of wind resources –On the strength of the underlying system in West Texas –On the availability of strong connections to the existing system near load centers

11 RPG CREZ Meeting3/28/2008 A Word of Thanks The planning team at ERCOT Stakeholders who have participated in this process and the Wind Integration study

Questions?

13 RPG CREZ Meeting3/28/2008 Certainty Optimized for Scenario 1 Optimized for Scenario 2 Optimized for Scenario 3 Optimized for Scenario 4 12 GW18 GW25 GW24 GW Collection systems, transmission from west to east, and integration into eastern portion of grid are well defined Recommended projects fit into plan for expansion to next level All relevant studies have been completed Transmission owners have agreed to feasibility of connections into existing facilities Some minor changes may be necessary as result of routing analysis

14 RPG CREZ Meeting3/28/2008 Some Additional Study Optimized for Scenario 1 Optimized for Scenario 2 Optimized for Scenario 3 Optimized for Scenario 4 12 GW18 GW25 GW24 GW Collection systems and transmission from west to east are well defined A viable, near-optimal plan for integration into eastern portion of grid has been identified Further work and a few changes in endpoints may be necessary before finalizing integration into the eastern portion of the grid –Additional requirements to address feasibility of upgrades in east –Need to include consideration of other requirements in east

15 RPG CREZ Meeting3/28/2008 Flexibility Optimized for Scenario 1 Optimized for Scenario 2 Optimized for Scenario 3 Optimized for Scenario 4 12 GW18 GW25 GW24 GW Collection systems in the west are well defined A viable plan for transmission from west to east and integration into eastern portion of grid has been identified, based on powerflow and stability Additional work will be needed; number and positioning of west to east paths may change, as well as system upgrades in the eastern portion of the grid