American Electric Power – Energized Reconductor
Lower Rio Grande Valley
Since 1996 American Electric Power’s peak load in the Rio Grande Valley has grown by 80%. In the winter of 2010 during an unusual cold snap a record 2,378 MW was consumed. This load was 300MW greater than the existing transmission system capacity causing some load to be shed during this peak demand. Compounding this problem, forecasts of predicted load were estimated to be 3,000 MW by the end of 2020. This growth required sufficient transmission to connect generation to load.
In 2012 the Lower Rio Grande Valley was served by 2 single circuit 345kV transmission lines which had been installed in the 1970’s and as a result of their proximity to the gulf of Mexico subjected to 4 decades of hurricanes and corrosion by salt water. In spite of the predicted load projections and the peak demand seen in 2010 a new line was unable to be built until sometime after 2020.
With no other options to meet this demand AEP turned to Quanta Energized Services for assistance. QES dispatched a team to Texas to look at the existing line and develop a work method that would safely and cost effectively meet the utilities goal. By installing high temperature low sag conductor (ACCC) in place of the existing 795 ACSR conductor QES was able to effectively double the rated amapcity of the existing 240 mile system. Given the demands on this critical system a long term outage was impossible; utilizing proprietary tools and methods QES was able to complete this entire project while the line remained energized.
Every step of AEP’s South Texas Project was reviewed, assessed and planned by senior QES technical advisors. AEP considered the capabilities and competency of the QES team to be the determining factor when deciding whether to undertake such a complex and unique project. The project was subdivided into 5 segments and AEP and QES developed an aggressive project schedule to meet the predicted load demands and maximize productivity on the project.
Several of Quanta Services Operating Units were brought on board to provide the necessary man power and resources to complete this project. At the start of the project the line was inspected by specially trained crews to verify its capacity to handle the upcoming work and to identify any corroded or damaged structures.
This project had many unique challenges but each one was overcome using proven and tested procedures and tools including the use of a “D-phase” mounted to temporary structures, trailer mounted breakers to make and break parallel circuits and equipotential zone work methods during the stringing process. The LineMaster Robotic Arm provided the brawn to move conductors and open up limits of approach when required.
The final phase featured another industry first when a double circuit section of 345kV and 138kV was successfully reconductor and upgraded all without a required outage. The Lower Rio Grande valley project is the longest energized reconductor project ever completed and the longest installation of advanced conductor in the United States.
Scope: Reconductoring to increase transfer capacity of existing lines
Quanta Team: North Houston Pole Line, Quanta Energized Services, Quanta Technology, Dashiell, Canfer
Line Condition Assessment