AEP Ohio Transmission Co. Inc. (AEP Ohio Transco) on July 22 proposed to the Ohio Power Siting Board to rebuild the existing 6.8 mile Yager-Desert Road section of the Dennison-Desert Road 69 kV electric transmission line in Harrison and Tuscarawas counties, Ohio.
Due to increased customer load growth in the area stemming from the Utica shale gas play, the circuit was determined to violate thermal limits in the future under certain conditions. In addition, the existing line has been in service since 1926 and has deteriorated to a level that no longer would meet AEP’s Transmission Line Engineering Standards (TLES).
Rebuilding the line will mitigate the overloading risk and enhance reliability for area customers. It will also resolve issues associated with the deterioration of the line and bring the line to current design standards. The proposed project will also improve local service for customers, decrease power interruptions, improve resiliency of the system, and speed recovery of local service when outages do occur. In addition, the project will facilitate the interconnection of new industrial customers to the AEP Ohio transmission system and support future economic development in the area.
This project is part of a larger program of improvements to the existing transmission service in eastern Ohio where AEP Ohio Transco has identified a critical need to reinforce its transmission system to maintain and improve the quality and reliability of electric service in the area. This project, as well as the adjacent Yager-Desert Road 138kV line rebuild, and Yager 138-69kV substation, are part of a PJM baseline RTEP reliability upgrade.
In this July 22 application, AEP Ohio Transco seeks a Certificate of Environmental Compatibility and Public Need from the Ohio Power Siting Board (OPSB) to enable timely commencement of construction activities.
The existing Dennison-Desert Road line provides 69 kV transmission service to the area, and serves AEP Ohio distribution, Carroll Rural Co-op, and major industrial customers. The line serves as a pathway in the transmission grid between distant sources at New Philadelphia, Newcomerstown, Carrollton and beyond. The line was originally constructed in 1926 using a combination of single pole and H frame wood construction.
Due to high customer load growth in Tuscarawas, Carroll and Harrison counties, the existing circuit will not be able to reliably operate for base case or contingency conditions, without being at risk of thermal overload. This could result in customer load being interrupted at times due to these thermal conditions. The rebuilt line will continue to serve the vicinity with 69 kV transmission service, but will be built to 138 kV design standards to enable more efficient future voltage conversion to support future load growth in the area.
Although the 69kV overload risk identified by AEP Ohio Transco and PJM Planning is the most pressing reason to upgrade the line, the decision to upgrade to 138 kV design specifications is driven by several other factors. These include that this line is located in one of the more active regions of the Utica shale play and AEP Ohio Transco anticipates load growth connecting either directly to the line or being served through pathways for which the line would be required. Constructing the line to 138kV standards now would reduce the risk of multiple and potentially more costly line rebuild projects in the future.
Surrounding 138 kV facilities have already experienced significant shale gas-related load growth and are undergoing various upgrades to address the short-term requirements. AEP Ohio Transco anticipates the need to upgrade surrounding 138 kV facilities in the future, which could potentially require extensive construction outages to critical load areas. Strategic conversion of the Dennison-Desert Road line through Yager Station to 138 kV will help provide much needed support to the existing surrounding 138 kV system when future upgrades are made.
In recent months, AEP Ohio Transco said iy has adopted new, more robust planning criteria for its sub-transmission facilities. These criteria will be used in PJM’s next RTEP process where modeled facilities are tested under specified criteria and any violations are assigned baseline corrections. In a preliminary study performed after the project had been developed, AEP Ohio Transco identified a thermal violation on the Dennison-Desert Road 69 kV line pursuant to the new criteria. This is in addition to the previously identified thermal violations for the project. These criteria violations are expected to be identified in the forthcoming RTEP process, which may result in a need to upgrade the operation of the line to 138 kV on an accelerated schedule.
The proposed project will extend from Yager Station, which is currently under construction, to the existing Desert Road Station for a total length of approximately 6.8 miles. The project will be constructed as a double circuit steel pole line with alternating zero degree braced post insulators or strain insulators on dead ends. The majority of the line will be constructed with direct embed poles or, in some cases, on concrete foundations of six to eight feet wide and approximately 25 to 40 feet deep.