The Eastern Interconnection Planning Collaborative on Sept. 10 issued a report identifying the baseline Interregional Transfer Capabilities (ITCs) across the Eastern Interconnection under extreme weather conditions.
The EIPC study was designed to identify the baseline ITCs for the existing bulk power system and transfer constraints between regions.
The study also focused on assessing the transfer capability between regions under extreme weather conditions where the interregional transfer capability has the most potential to provide value to all regions within the interconnection.
In this study, the EIPC took a unique and innovative approach through utilizing credible stress scenario tests that rely on actual meteorological data and trends, it said.
“The lessons learned from this work are now available for transmission planners across the region to use in analyzing specific interregional transfer capability improvements,” said Jordan Bakke, director of strategic insights and assessments at the Midcontinent ISO and chair of the EIPC Executive Committee.
The EIPC, made up of 18 planning authorities from the eastern and central United States, provides a forum for interconnection-wide coordination of system planning activities of its member regions in the Eastern Interconnection. Since its inception, EIPC has performed periodic ITC studies.
The planning authorities include the following public power entities:
- Santee Cooper
- Tennessee Valley Authority
- MEAG Power
The current study is the result of a number of recent EIPC ITC initiatives, starting with EIPC testimony outlining considerations and a path forward presented at FERC’s ITC Workshop in December 2022, the issuance of a 2023 EIPC white paper, which identified important technical considerations in determining an appropriate level of ITC that ensures the continued reliability of the transmission grid, and the February 24, 2025, submission of formal comments by EIPC to FERC on the NERC Interregional Transfer Capability Study (ITCS) and recommendations as to an appropriate path forward for consideration by FERC.
The study is independent of the NERC ITCS and does not incorporate the same ITCS inputs or results. It also does not recommend “prudent additions," it said.
The EIPC ITC study was intended to perform an interconnection-wide assessment and identification of constraints.
Consistent with state and federal law, consideration of specific transmission projects remains the responsibility of individual EIPC planning authorities.
The study established the baseline ITC for the existing system under system summer and winter peak load levels. It identified transfer “bottlenecks” between regions using cases adjusted to reflect the five most stressful extreme weather conditions, both heat and cold, for the Eastern Interconnection derived from the meteorological study.
The incorporation of the meteorological study makes the identification of transfer capability unique by incorporating the worst weather conditions since 1980 to better understand ability of individual regions within the Eastern Interconnection to support each other in times of extreme stress.
The report presents a summary of the most frequently limiting constraints under all of the five extreme weather events for use by regional planning coordinators in their future studies.
"Critical work in this area relies on the expertise of transmission planners working with their respective states and stakeholders who have the full knowledge of their respective systems, general trends under which interregional transfers would be most helpful, and where the best value investments to enhance those capabilities exist," EIPC said.
The EIPC continues to serve as a coordinator for such activities. While recognizing the need to respect regional differences, EIPC has, through its comments presented to FERC in February 2025, proposed a process to develop consistent metrics to help guide decisions on possible enhancements to interregional transfer capability.
These metrics should include consideration of the need, as well as the cost/benefit and feasibility of a given project to meet the identified need, it said.
"EIPC and its members stand ready to provide technical assistance to federal and state policymakers to support such an effort in the Eastern Interconnection and share its member’s expertise with other jurisdictions across the nation," it said.
EIPC said it will continue providing a role in coordinating Eastern Interconnection-wide transfer studies that can identify the constraints that limit transfers between regions.
