AEP Texas Inc., on Oct. 12 filed with the Public Utility Commission of Texas an application to amend its certificate of convenience and necessity (CCN) to build about 1.7 miles of new single-circuit, 138-kV transmission line in Knox County, Texas.
The Tardis to Benjamin Tap 138-kV Transmission Line Project would extend between the proposed AEP Texas Tardis switching station, to be built east of the City of Benjamin on U.S. Highway 82, to an interconnection point located on the existing Benjamin Tap 69-kV transmission line. The company added that that interconnection point is referred to as the “cut-in location.”
From the cut-in location to the existing AEP Texas Benjamin substation, the western portion of the existing Benjamin Tap 69-kV line would be rebuilt and upgraded to a 138-kV line. The company also said that the AEP Texas Benjamin substation would be expanded for 138-kV operation. In addition, the existing AEP Texas Paducah Clare Street to East Munday 138-kV line would be extended into the proposed Tardis switching station, which is adjacent to the Paducah Clare Street to East Munday line.
Together, all of those projects would provide a 138-kV source to the Benjamin substation, the company added. The construction of the Tardis switching station, the expansion of the existing Benjamin substation, the rebuilding and upgrading of the existing Benjamin Tap 69-kV line, and the extension of the existing Paducah Clare Street to East Munday line into the proposed Tardis switching station would all be accomplished as routine activities that do not require a certificate amendment, and are not included in the CCN filing, the company said.
Discussing the need for the proposed project, the company noted that the area north of the City of Aspermont is currently served by Brazos Electric Power Cooperative 69-kV transmission lines with AEP Texas 138-kV sources in the Aspermont and East Munday substations. In addition to the communities in that area, the load is primarily related to oil field pumping and is forecast to increase in the next several years.
The company added that studies have shown that adequate voltage cannot be maintained during an outage of a 138/69-kV autotransformer in either Aspermont or East Munday, or the respective Brazos Electric 69-kV transmission line when another system component in the area is out of service (N-1-1). The electrical system is intended to be operated N-1 secure, making maintenance in the area problematic, the company said, adding that a maintenance outage of any of those system components would result in the need for load shedding so that N-1 security can be maintained.
The company noted that the project and the routine activities associated with the CCN filing are part of an overall network improvement program recommended by ERCOT that also includes the Brazos Electric Gyp to AEP Texas Benjamin 138-kV line that was approved in commission Docket No. 47691.
The company noted that 100% of the right of way (ROW) has been acquired from the two landowners crossed by the proposed route. The area traversed by the proposed route is located in the central portion of Knox County – in the North Central Plains region – and is characterized by questas or parallel low north-south ridges. The company added that the study area is rural and the predominant land use is rangeland. The majority of the study area has been impacted by land improvements associated with agriculture, roadways, oil and gas activities, as well as various utility corridors. Overall, the company added, the study area viewscape consists of open rangeland/pastureland.
Considering the short distance between the proposed Tardis switching station and the Benjamin Tap line, the proximity of the Tardis switching station to the existing AEP Texas Paducah Clare Street to East Munday line, and the agreement of the two affected landowners to negotiate an easement, only one route was considered for the project, the company said. The proposed route is parallel and adjacent to the existing AEP Texas Paducah Clare Street to East Munday line for 93.5% of its length, deviating only where it enters the Tardis switching station, the company noted.
Discussing the estimated costs for the proposed route and the Tardis switching station, the company said that the estimated total cost for the transmission facilities is about $3.3m, and about $6.3m for the substation facilities.
According to the estimated schedule, engineering and design began in March and would be completed in February 2019; material and equipment procurement would begin in December and be completed in May 2019; and construction of facilities would begin in March 2019 and be completed in September 2019, which is also when the facilities would be energized.