PPL’s (NYSE:PPL) PPL Electric Utilities on June 26 filed with the Pennsylvania Public Utility Commission (PUC) a letter of notification to request approval to rebuild and construct 230-kV transmission lines needed to interconnect the proposed new Williams Grove 230-69-kV substation located in Upper Allen Township, Cumberland County, Pa.
To interconnect the new substation to the 230-kV system, PPL Electric proposes to rebuild about 3.9 miles of the existing single-circuit Cumberland-West Shore 230-kV Transmission Line as a double-circuit 230-kV transmission line, and to build about 0.3 miles of new 230-kV transmission lines that would be located entirely within the proposed substation property.
The project, which would be located in Upper Allen Township, is needed to avoid multiple reliability issues, and to reinforce the 230-kV and 69-kV systems serving Cumberland County, the company added.
The proposed project is one part of a large comprehensive plan to improve the reliability of service to about 130,000 customers served from the West Shore, Cumberland, and Juniata 230-69-kV regional substations in the greater Harrisburg area, the company said.
The comprehensive plan is designed to improve the reliability of the transmission and distribution systems serving the greater Harrisburg area by replacing facilities that have reached the end of their useful lives, and do not meet current design standards, with modern facilities that meet current design standards and have the technical ability to reduce the potential and duration of outages experienced by customers, the company said. The improved transmission and distribution systems would allow quicker load restoration after a system interruption, which would contribute to a higher level of reliability for the customers served from those lines, the company said.
Presently, customers in Cumberland County receive their bulk electric power supply from multiple 230-kV lines, which provide power to two regional transmission substations, the Cumberland 230-69-kV substation and the West Shore 230-69-kV substation.
The company also noted that the Cumberland substation is interconnected with the West Shore substation by the approximately 11.6-mile, single-circuit Cumberland-West Shore line.
The Cumberland substation is interconnected with the Brunner Island 230-69-kV Substation via the Brunner Island-West Shore #1 230-kV Transmission Line.
The Cumberland substation and the West Shore substation supply several 69-kV transmission lines, which in turn supply various 69-12-kV distribution substations in Cumberland County, the company added, noting that those 69-12-kV distribution substations supply power to the majority of commercial and residential homes in the area.
The Cumberland-West Shore #3 and Cumberland-West Shore #4 69-kV transmission lines extend about 20 miles and 23 miles, respectively, between the Cumberland and West Shore 230-69-kV substations. The company also said that the Cumberland-West Shore #3 and Cumberland-West Shore #4 69-kV transmission lines are networked lines that occupy common tower structures.
Further discussing the need for the project, the company noted that studies conducted for its transmission system, in conjunction with the PJM Interconnection Regional Transmission Expansion Plan (RTEP) process, revealed that the Cumberland-West Shore #3 and Cumberland-West Shore #4 69-kV transmission lines are at risk of excessive load drop by summer 2018 in violation of PPL Electric’s reliability practices.
The company said that its new Williams Grove substation would provide a new 230-kV backbone source that would be located more central to the load it would serve. With the new Williams Grove substation and 230-kV connecting lines, PPL Electric would be able to remediate the significant initial load drop violation; reduce the overhead transmission line exposure by shortening the distances of the Cumberland-West Shore #3 and #4 69-kV lines; and operate the Cumberland-West Shore #3 and #4 69-kV lines radially, rather than in network, to improve system reliability.
The company added that the site for the proposed Williams Grove substation is crossed by the existing 11.6-mile, single-circuit Cumberland-West Shore transmission line, which would be split and tied into the substation.
About 3.9 miles of the existing Cumberland-West Shore line between the Cumberland substation and the new Williams Grove substation would be renamed the Cumberland-Williams Grove 230-kV Transmission Line, the company said. To tie the existing single-circuit 230-kV line into the new Williams Grove substation, PPL Electric proposes to build about 0.12 miles of new 230-kV transmission line, the company said, adding that the 0.12-mile segment of new transmission line would be located entirely on the company owned site for the Williams Grove substation. No additional right of way (ROW) is required for the construction, operation, or maintenance of that new segment of 230-kV transmission line, the company said.
About 3.9 miles of the existing Cumberland-West Shore line between the West Shore substation and the proposed Williams Grove substation would be renamed the Williams Grove-West Shore 230-kV Transmission Line, the company said, adding that that existing single-circuit would be rebuilt for double-circuit operation. One side of the rebuilt double-circuit would accommodate the renamed Williams Grove-West Shore line, and the other side of the double circuit structures would accommodate the Brunner Island-Williams Grove 230-kV line, the company said, adding that no new ROW is required to rebuild the approximately 3.9 miles of the existing single-circuit Cumberland-West Shore line for double-circuit operation.
The new Williams Grove-West Shore and the Brunner Island-Williams Grove circuits would occupy common double-circuit structures between the Williams Grove substation and the West Shore substation, and would enter the Williams Grove substation on the same set of structures, the company said.
To interconnect that rebuilt double circuit line with the Williams Grove substation, the company proposes to build about 0.18 miles of new 230-kV transmission line. the 0.18-mile segment of new line would be located entirely on the PPL Electric-owned site for the Williams Grove substation, and no additional ROW is required for the construction, operation, or maintenance of that new segment of 230-kV line, the company added.
The new and rebuilt 230-kV transmission lines would consist of self-weathering steel monopoles equipped with steel arms and glass 230-kV insulator assemblies, three power conductors, and two optical ground wires, the company said, noting that the new structures are expected to range between 105 and 145 feet in height, with an average height of about 130 feet.
The project’s total estimated cost is about $15m for the construction of the proposed 230-kV transmission lines, the company said.
Among other things, the company said that subject to the PUC’s approval, construction is scheduled to begin in September to support an in-service date of September 2018.