Enhancing Grid Development through Integration of ISO/RTO Planning Functions

Independent System Operators (ISOs) and Regional Transmission Organizations (RTOs) are responsible for coordinating strategic planning for large-scale power systems. Transmission planning has always been central to grid development, but it is even more so today due to the proliferation of renewable energy resources. These changes require well-organized coordination of intraregional and interregional planning functions and advanced computational tools to determine transformations needed for efficiently meeting electricity demands. This paper summarizes the planning processes employed by ISO/RTOs in North America and France. It also proposes a framework that integrates the main planning functions, including a software system called the Expansion Planning Modeling System (EPMS) to facilitate long-term planning. The adoption of the proposed approach will empower ISO/RTOs with efficient decision-making capabilities to develop flexible portfolios for the long-term horizon, considering costs and reliability in the face of high uncertainty.