From Knowledge Problem:
More, including a fist full of links, including this Fort Worth Star-Telegram story "Oncor will build $1.3 billion worth of wind transmission lines" which identifies the companies as:
On Thursday, Texas utility regulators selected nine companies to build portions of the nearly $5 billion-worth of transmission to better connect existing and anticipated generating resources in the western part of the state to the large consumer load centers in the east, central and southeast parts of the state. (Most of those existing and anticipated generators are wind powered, but so far as I know nothing in the rules would prevent a company from building a coal plant in west texas and getting access to the grid.)
This map posted on the PUCT website shows the approximate assignment of lines to companies. Note that one project in the McCamey area was assigned to STEC, but is not shown on the map. Click on the image for a larger view.
...Others companies landing major parts of the project are: Cross Texas Transmission; Electric Transmission Texas, a joint venture between Mid-American Energy Holdings and American Electric Power; Lone Star Transmission; the Lower Colorado River Authority; Hunt Oil-owned Sharyland Utilities; and Wind Energy Transmission Texas, part of Spain-based Isolux Corsan. Two other companies received smaller shares....