Virginia State Corporation Commission staff, in a May 21 report, told the commission that it does not oppose Appalachian Power Company’s (APCo) request that the commission issue a certificate of public convenience and necessity (CPCN) necessary for a proposed project that includes a new substation.
As noted by staff, APCo filed an application with the commission requesting a CPCN to build the new Wolf Glade substation; extend the existing Wolf Glade 138-kV transmission line; relocate the existing Cliffview 69-kV Tap; as well as retire the existing Cliffview substation and about 14 miles of the double-circuit, 88-kV – operated at 69 kV – transmission line between the Byllesby and Wythe substations; and make improvements to the Jubal Early and Huffman substations.
According to the company, the approximately two-mile proposed route for the Wolf Glade 138-kV Extension would require new right of way (ROW) easements, begins at a tap point at Structure 134-32 on the existing Jubal Early-Piper’s Gap 138-kV transmission line, about 0.3 mile west of Hebron Road, and runs south for about 0.8 mile through agricultural and pasture land. Staff added that the route then turns southwest for about 0.3 mile and turns south for about 0.4 mile, crossing Creekview Drive. The route then enters the proposed Wolf Glade 138-kV substation site.
Staff also said that according to the company, the project is needed to address projected thermal and voltage violations of the American Electric Power (AEP) transmission planning reliability criteria on several 69-kV facilities in the Galax Load Area – that is, the City of Galax, as well as parts of Carroll and Grayson counties – under certain N-1-1 contingencies, and projected 2021/22 winter peak loading conditions.
Staff said that the proposed project is estimated to cost about $38m (about $13m for transmission line work and $25m for substation work), with an expected in-service date of December 2021. The retirement of the Cliffview substation, of about 0.2 miles of the double-circuit, 69-kV tap, and of about 14 miles of the 88-kV double-circuit line between Byllesby and Wythe, to be done after the proposed project is completed, have an estimated conceptual cost of $10m, staff said.
Staff said that its analysis showed that the proposed project successfully resolves the identified AEP criteria violations and that based on that review, staff concludes that the company has reasonably demonstrated a need for the proposed project.
Further discussing the need for the project, staff noted that two N-1-1 contingency violations were identified in the area under projected winter 2021/22 peak load conditions. The worst of the two N-1-1 contingencies that cause thermal and voltage violations in the Galax Load Area under projected winter 2021/22 peak load conditions is the N-1-1 loss of the Jubal Early 138/69-kV transformer followed by the loss of the Byllesby-Wythe 69-kV circuit, staff said.
Under that scenario, thermal violations are projected to occur on the Cliffview-Lee Highway 69-kV line section and on the Wythe 138/69-kV transformer, as well as voltage magnitude and deviation violations on the 69-kV system at Cliffview, Galax, Fries, Byllesby, and Independence substations.
Staff added that according to the company, when the main source from the Jubal Early 138/69-kV transformer is lost, the Galax area must be served from the Wythe 138/69-kV transformer, which is not an adequate source for the area. The two 94-year-old 69-kV circuits serving the Galax area from the Wythe substation do not have adequate capacity to support the Galax area load under projected winter 2021/22 peak load conditions, hence the projected violations, staff said.
Staff noted that it was able to replicate the company’s power flow analyses using modeling data provided by the company and was able to verify the results presented in the application.
Discussing the project, staff noted that the company proposes to build the Wolf Glade substation at the end of Jack Guynn Drive on a 16.7-acre parcel owned by the company and located behind the Guardian Glass manufacturing facility. The proposed improvements at the Jubal Early substation would be entirely contained within the existing fence line of the substation and would include, among other things, installation of one 138/69-kV transformer, staff noted.
Of the line, staff said that according to APCo, each of the proposed three-phase 138-kV and 69-kV circuits would consist of non-specular three 795 thousand-circular-mil aluminum conductor steel reinforced (ACSR) “Drake” conductors with 26/7 stranding. The proposed double-circuit transmission lines would use one Alumoweld ground wire and/or one 0.646-inch diameter optical ground wire (OPGW) for lightning protection, staff said. APCo asserts that the proposed Wolf Glade 138-kV Extension would be a double-circuit transmission line – Huffman-Wolf Glade 138-kV circuit and Jubal Early-Wolf Glade 138-kV circuit – with a three-phase design. Each circuit would have a nominal phase-to-phase design voltage of 138-kV and would be operated at 138 kV with an overall maximum load transfer capability of 255 MVA and 303 MVA, staff added.
The company anticipates using double-circuit steel monopoles with davit arms for the proposed 138-kV and 69-kV transmission lines. Staff also said that a 138-kV two-pole dead-end structure may be used at the Wolf Glade Extension tap location and considered for use at heavy line angle locations. The company proposes to use about 14 dulled galvanized steel 138-kV double-circuit monopole structures with davit arms and one double-circuit two-pole dead-end 138-kV structure for the Wolf Glade 138-kV extension.
For the relocated Cliffview 69-kV Tap, the company proposes to use about six dulled galvanized steel 69-kV double-circuit monopole structures with davit arms, staff added.
Discussing environmental, scenic, and historic impacts, staff said that the company asserts that 13 sites were considered for the new Wolf Glade 138-kV substation and that ultimately, it determined that the site on Jack Guynn Drive was the best available site for the proposed substation. The proposed site was previously graded by the City of Galax for a future industrial site, which the company describes as flat, clear of trees, at the end of a well-maintained public road, as well as away from residences and Glendale Road. Staff added that the company purchase the property from the City of Galax for the construction of the substation.
Of the relocated Cliffview 69-kV Tap, staff said that a siting study identified 20 dwellings within 500 feet; seven dwellings and seven barns, outbuildings, sheds, garages, and silos within 250 feet of the centerline of the proposed ROW; and one designated place of worship within 1,000 feet of the proposed ROW centerline. The centerline of the proposed ROW crosses four parcels owned by four different landowners.
Of the Wolf Glade 138-kV Extension, staff said that a siting study identified two dwellings within 500 feet and one cemetery within 250 feet of the proposed ROW centerline, which crosses five parcels owned by five different landowners.
Among other things, staff said that the proposed project utilizes existing ROW and appears to minimize impact on existing residences, scenic assets, historic districts, and the environment.