FirstEnergy‘s (NYSE:FE) Potomac Edison on Feb. 27 requested a waiver from the Maryland Public Service Commission of the certificate of public convenience and necessity (CPCN) requirements so as to permit the company to run a short loop line from the existing Doubs-Monocacy 230-kV Transmission Line to a new 34.5-kV sub-transmission substation to be built later this year in order to support improved distribution system reliability.
The company added that it is proposing to build a 115-foot, 230-kV loop line between the Doubs-Monocacy Line and a proposed new substation to be named West Jefferson. The Doubs-Monocacy Line begins at the Doubs substation, located near Point of Rocks, Frederick County, Md., and then traverses about 25 miles north and east to the Monocacy substation, located in Frederick, Frederick County. The company added that the Doubs-Monocacy Line is one of two lines carried on double-circuit, steel lattice towers, with the other being the Frostown Junction 230-kV transmission line.
The new loop would be located off Burgee Drive, just south of US Route 340.
The company also said that the project requires installation of two new in-line steel pole structures – #135A and #135B – to be located between existing lattice towers #135 and #136. Structure #135A would be the loop structure and structure #135B would be a strain structure to maintain clearances between the adjacent Frostown Junction 230-kV line and the loop structure.
Potomac Edison added that the tops of both new structures would be about 115 feet above ground. The heights above ground of the existing adjacent lattice towers #135 and #136 are 134 feet and 133 feet, respectively. The company added that the average structure height of the entire Doubs-Monocacy line is 130 feet.
The new loop line would extend northeast from structure #135A for about 115 feet across land owned by Potomac Edison. The company added that the new single-circuit loop would consist of six 1272 kcmil, 45/7 ACSR conductors and two 7#6 alumoweld shield wires. The project is designed to include a 29-foot minimum conductor to ground clearance with a thermal rating of 212°F.
Potomac Edison also said that construction of the 230-kV loop is expected to cost about $1m, and the entire West Jefferson reliability upgrade project – including the loop line – is anticipated to cost around $10m.
The company said that it plans to begin construction on the project in January 2020, and that when completed, the operation of the West Jefferson substation is expected to enhance service reliability for the 4,300 customers served from the existing Brunswick and Jefferson substations. Brunswick, Jefferson, and Petersville substations are all currently served from the 23-mile Lime Kiln-Millville 34.5-kV line. Serving all three substations radially from either the Lime Kiln substation or the Millville substation under heavier loading conditions could result in voltage and thermal loading violations, the company added.
Furthermore, not being able to radially serve the Brunswick substation or the Jefferson substation during source outages has resulted in reliability issues, the company said, noting that in the last five years, Potomac Edison has experienced 12 source outages for the Brunswick and Jefferson substations. Building the West Jefferson substation as an additional source for the circuit would mitigate voltage collapse and thermal overloads when the line is operated radially from either end, and would also mitigate source outages to the Brunswick and Jefferson substations, the company said.
PUA Section 7-207(b)(4)(i) states that “for construction relating to an existing overhead transmission line designed to carry a voltage in excess of 69,000 volts, the commission shall waive the requirement to obtain a certificate of public convenience and necessity if the commission finds that the construction does not,” for instance, require the person to obtain new real property or additional rights of way (ROWs) through eminent domain, the company noted.
Potomac Edison said that the loop line project relates to the existing Doubs-Monocacy Line. All work on the loop line and substation would be performed on property already owned by the company, so no question of eminent domain authority would arise, the company said, adding that there also would be no increase in the voltage or the size of any conductor. In addition, the two new structures would be lower than the existing structures on the Doubs-Monocacy Line, the company said.