Southwest Power Pool has issued a report on its EHV Overlay Project, which provides innovative blueprints for the future of the transmission grid for SPP and its neighboring regions. This report, which was independently prepared by InfraSource Technology and PowerWorld Corporation, provides a strategic assessment of how to meet SPP’s future reliability and capacity needs through the use of a 500 and 765 kV transmission system overlaying the existing SPP footprint and integrating with the existing EHV systems of Entergy, MISO, and PJM. An EHV Overlay would:

• Enhance reliability by providing a stronger transmission system for the communities within SPP’s footprint.
• Provide greater access to transmission service customers seeking to deliver environmentally friendly, renewable energy from existing and potential wind farms in the South Central portion of the United States. 
• Position SPP to become part of an enhanced transmission system extending across the Eastern Interconnection, increasing access for U.S. electricity customers.

The InfraSource Technology and PowerWorld Corporation team considered the challenges of operating the electric system up to the year 2026 and identified an optimized package of projects designed to satisfy the needs of SPP and its member systems. The team used an innovative screening methodology to test many system configurations and performed detailed analysis on six leading alternatives. The top-performing alternative, which has a cost estimate of almost $5 billion, is a 765 kV loop in the central part of SPP’s footprint with connections extending to MISO/PJM, SERC, and ERCOT. The study identified strong performance of a 765 kV interconnection from SPP to MISO (near St. Louis) and continuing into PJM (near Chicago). The plan also includes an extensive 500-kV expansion in Arkansas, Missouri, and Texas, which would integrate into existing Entergy and SPP systems.

According to Jay Caspary, SPP engineering director, the EHV Overlay Project meets the Regional Participation planning principle of the Federal Energy Regulatory Commission’s Order 890, which requires transmission providers to coordinate with interconnected systems to share plans and identify enhancements. "The EHV Overlay Study provides a foundation for long range planning and detailed economic assessments that can help SPP work with our neighbors to create an interstate transmission superhighway."