Capricious Cables: Understanding the Key Concepts in Transmission Expansion Planning and Its Models

The extra-high-voltage transmission network is the bulk transport network of the electric power system. To understand how the future power system may react to planning decisions today, wide-area transmission models are increasingly used to aid decision makers and stakeholders. The goal of this work is to illuminate these models for a broader audience that may include policy makers or relativenewcomers to the field of transmission planning. This paper explains the basic transmission expansion planning model formulation. It highlights six of the major simplifications made in transmission expansion planning models and the resulting need to contextualize model results using knowledge from other models and knowledge not captured in the modeling process.