The Texas Interconnection is an alternating current (AC) power grid - a wide area synchronous grid - that covers most of the state of Texas. The grid is managed by the Electric Reliability Council of Texas (ERCOT).
The Texas Interconnection is one of the three minor grids in the continental U.S. power transmission grid. The other two minor interconnections are the Quebec Interconnection and the Alaska Interconnection. The two major interconnections are the Eastern Interconnection and the Western Interconnection. The Texas Interconnection is maintained as a separate grid for political, rather than technical reasons.
All of the electric utilities in the Texas Interconnection are electrically tied together during normal system conditions and operate at a synchronized frequency operating at an average of 60 Hz.
Interconnections can be tied to each other via high-voltage direct current power transmission lines (DC ties), or with variable-frequency transformers (VFTs), which permit a controlled flow of energy while also functionally isolating the independent AC frequencies of each side. The Texas Interconnection is tied to the Eastern Interconnection with two DC ties, and has a DC tie and a VFT to non-NERC systems in Mexico. There is one AC tie switch in Dayton, Texas that has been used only one time in its history (after Hurricane Ike).
On October 13, 2009, the Tres Amigas SuperStation was announced to connect the Eastern, Western and Texas Interconnections via three 5 GW superconductor links. As of 2017 , the project was reduced in scope and only related infrastructure was constructed for nearby wind projects connecting to the Western Interconnection.