CREZ Optimization Studies Scenario 2, Alternative 4: Low Impedance Backbone for Wind Connections Cathey Carter, PE RPG CREZ meeting 12/14/2007

2 Description This solution starts with a transmission backbone between one central point and the three load centers. The central point is not connected to the existing network. The endpoints are Zenith near Houston, Trinity between Dallas and Fort Worth, and West Gate outside Austin – San Antonio. Each endpoint must be well developed to the local load-delivery network. Additional substations can be installed any where on the lines to attach new generation.

3 Goals 1.Reduce impedance and phase angles between the three heaviest load areas. 2.Provide a strong “target” for new transmission lines from large new generation sources. Any big generator could build to the closest part of the backbone. 3.Reduce loading on existing major paths.

4 Other Possible Effects, Good and Bad 1.Improve dynamic stability? 2.Decrease loading on the biggest existing transmission paths. 3.Reduce nodal price differences among the load centers? 4.Possibly the maximum construction cost. 5.Likely public opposition along ROW, which is true for any new construction. 6.Will require upgrades of existing network for n-1 security.

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6 Current Status of Study = Incomplete Zenith Sub Connections: 50 mile 765kV line to Bryan rated 6625 MVA (2) 2100 MVA autos to 345kV system (2) 345kV lines to O’Brien, each rated 1450 MVA (2) 345kV lines to Singleton, each rated 1450 MVA (2) 345kV lines to TH Wharton, each rated 1499 MVA

7 Current Status of Study = Incomplete Bryan Sub Connections: 50 mile 765kV line to Milam rated 6625 MVA 50 mile 765kV line to Zenith rated 6625 MVA (1) 2100 MVA kV auto, new 345kV bus (1) 600 MVA kV auto, new 138kV bus 10 miles 138kV line to BRYN_SWTCH rated 469 MVA 10 mile 138kV line to BRYN_DSBY rated 469 MVA

8 Current Status of Study = Incomplete Milam Sub Connections: 50 mile 765kV line to Bryan rated 6625 MVA 70 mile 765kV line to Corsicana rated 6625 MVA 35 mile 765kV line to Mid rated 6625 MVA

9 Current Status of Study = Incomplete Corsicana Sub Connections: 70 mile 765kV line to Milam rated 6625 MVA 75 mile 765kV line to Trinity rated 6625 MVA (2) 2100 MVA autos to new 345kV bus at existing crossing of two transmission corridors (2) 345kV lines to Venus rated 1072 MVA (2) 345kV lines to Watermill rated 1631 MVA (2) 345kV lines to Big Brown rated 1072 MVA (2) 345kV lines to Limestone rated 1631 MVA

10 Current Status of Study = Incomplete Trinity Sub Connections: 75 mile 765kV line to Corsicana rated 6625 MVA (2) 2100 MVA autos to new 345kV bus (1) 345kV line to Benbrook rated 2988 MVA (2) 345kV lines to Everman rated 2988 MVA (2) 345kV lines to Liggett rated 2988 MVA (1) 345kV line to Hicks rated 2988 MVA (1) 345kV line to Saginaw rated 2988 MVA, plus (2) 800 MVA kV autos at Saginaw (1) 600 MVA kV auto to existing Trinity 138kV bus

11 Current Status of Study = Incomplete Mid Sub Connections: 35 mile 765kV line to Milam rated 6625 MVA 65 mile 765kV line to West Gate rated 6625 MVA (2) 2100 MVA kV autos (2) 345kV lines to Salado rated 1631 MVA (1) 345kV line to Zorn rated 1630 MVA (1) 345kV line to GILLE345 rated 1630 MVA (1) 686 MVA kV auto

12 Current Status of Study = Incomplete West Gate Sub Connections: 65 mile 765kV line to Mid rated 6625 MVA (2) 2100 MVA kV autos (1) 345kV line to Red Creek rated 3000 MVA (1) 345kV line to Willow rated 1959 MVA (1) 345kV line to Gillespie rated 1959 MVA, plus (2) 800 MVA kV autos, and a 345kV line to Kendall also rated 1959 MVA (1) 345kV line to Lampasas rated 1959, plus (2) 800 MVA kV autos

13 Current Status of Study = Incomplete Other New Lines in the Model: 32 mile 345kV Hicks-Willow 2 nd Willow – Jacksboro 345kV line on same towers 2 nd Oklaunion – Bowman 345kV line on separate ROW 2 nd 345kV Twin Buttes – Red Creek line, separate ROW 20 mile 345kV Bitter Creek – Bluff Creek line 130 mile 345kV Bluff Creek – Lampasas line 30 mile 345kV Goat – Red Creek line 130 mile 345kV Red Creek – West Gate line

14 Current Status of Study = Incomplete Other Changes to the Model, not Lines: 345kV ring bus at Paint Creek, not connected to anything else All 69kV and 138kV lines between Abilene and Stephenville converted to short radials Trinity 138kV buses connected. (2) kV autos at IRV Valley Ranch 138kV load and capbank moved from Hurst N to Hurst S 69kV Seymour – Bomarton disconnected 69kV Winters – Hatch disconnected 345kV connection to Big Spring, and 138kV Midland East – Big Spring rebuilt for 469 MVA

15 Comments Please direct comments to Warren Lasher or Cathey Carter. Warren: Cathey: