Competitive Renewable Energy-Zone (CREZ) projects comprise the majority of planned improvements in several ERCOT territories, the independent system operator said in its annual transmission report, released Jan. 16. The improvements would ease congestion in those territories.
The Electric Reliability Council of Texas said in the “Report on Existing and Potential Electric System Constraints and Needs” that about $8.7bn in transmission improvements are planned for the five-year period from 2012 to 2016.
“The projects that are being considered through the years 2012-2016 are expected to add over 5,047 miles of new circuits, upgrade or improve over 1,653 circuit miles of transmission lines, adding over 359 MVar of capacitor support, 900 MVar of reactor support and add 17,336 MVA of autotransformer capacity,” ERCOT said in the report.
Planned improvements in the Far West, North, North Central and West Weather Zones will primarily be CREZ-related. The CREZ program in total is expected to cost $6.87bn, according to a November 2011 quarterly update.
In the Far West zone, which contains the cities of Midland and Odessa, the Bakersﬁeld to Big Hill 345-kV line, the Sand Bluff to Long Draw to Scurry County South 345-kV lines and other new 345-kV lines will serve the CREZ zones and move generation, primarily wind, from west Texas to the population centers such as Dallas/Fort Worth, Austin and San Antonio, ERCOT said.
The Midland East to Stanton East upgrade will mitigate wind generation related congestion, ERCOT said. The 138-kV upgrade is scheduled for completion in May 2014.
ERCOT attributed most of the projected congestion in the Far West zone to growth in wind generation in west Texas, but noted that a majority of these constraints, such as on the Fort Stockton Switching Station to Barrilla Junction 69-kV line, will be relieved by the CREZ transmission upgrades.
In the North zone, the Krum West to Riley (Oklaunion) to Edith Clarke 345-kV lines, Cottonwood to Dermott and Edith Clarke 345-kV lines and other new 345-kV lines comprise the majority of planned improvements. These lines, too, are designated to serve CREZ zones and move primarily wind generation from west Texas to population centers.
ERCOT attributed most of the projected congestion in the North zone to “the addition of generation to that part of the transmission network that was originally designed to serve a relatively small load.” Congestion on the Spur to Girard Tap 69-kV line, for example, is attributable to the substantial increase in wind generation plants.
The Spur 138/69-kV autotransformer will remain congested until the CREZ upgrades are completed, while congestion on the Seymour to Bomarton 69-kV line will be reduced “signiﬁcantly,” though not completely eliminated, ERCOT said.
In the North Central zone, which contains the cities of Dallas and Fort Worth, ERCOT listed as CREZ projects the West Shackelford (Central C) to Sam Switch/Navarro 345-kV lines and substations, the Willow Creek to Clear Crossing to Dermott Switch 345-kV lines, the Brown to Newton to Killeen Switch 345-kV line, and several other 345-kV and 138-kV lines.
Unlike the Far West and North zones, the North Central zone’s congestion is a byproduct of large demand in the area.
In the West zone, CREZ projects Big Hill to Kendall 345-kV, Scurry County to West Shackelford 345-kV, Dermott to Willow Creek 345-kV and several other 345-kV transmission lines comprise the majority of upgrades.
“This new construction will serve the purpose to move power, mainly wind, from west Texas to other zones such as North Central, South Central and South,” ERCOT said, adding that the Ballinger to Winters 69-kV line upgrade will improve reliability in the area.
“While moderate load growth has contributed to some congestion, a majority of the constraints projected in the West Weather zone is mainly caused by the large increase in wind generation in the area,” ERCOT said. “Some of the congestion will be mitigated with the implementation of the CREZ transmission upgrades.”
ERCOT added that new CREZ facilities, when they enter service in the 2012-2013 period, will likely relieve congestion constraints on the West to North Transient Stability Limit in 2012.
Though many of the projects in the South Central zone are to meet growing demand in the san Antonio and Austin metropolitan centers, the area will see increased reliability from the Kendall to Miller to Paleface 138-kV upgrade and the Kendall autotransformer replacement, which will improve wind generation movement from the West zone, ERCOT said.
In the Southern zone, the most substantial planned improvement is the Lobo to Rio Bravo to North Edinburg new 345-kV line, ERCOT said.
In the East zone, system improvements will facilitate greater power imports into the Dallas/Fort Worth area. Congestion in the East zone arises from new coal-ﬁred plants and will occur on the 345-kV system between Central Texas and the Houston area.
In the Coast zone, system improvements will bring power into the Houston area. Congestion in this zone is expected to continue in the near future.
ERCOT has a total of 38,329 MW of wind interconnection requests, of which 19,666 MW are from wind power.