Comparison Between Transportation and Disjunctive DC Models in the Transmission Expansion Planning

This paper presents a comparative analysis of two models for direct current (DC) networks used in transmission expansion planning (TEP) problems. These models incorporate distinct sets of constraints and have different levels of detail: the transportation model incorporates only Kirchhoff’s First Law, while disjunctive model represents both Kirchhoff’s Laws. The choice of an appropriate modeling approach is a critical decision for planners, as it directly impacts the accuracy and feasibility of expansion plans. This study examines the impact of these different DC system representations, particularly in multi-terminal configurations with closed meshed topologies, on power flow calculations and system expansion investments. Although these models are well established for alternating current (AC) networks, their application to the DC portion of power systems is still under development regarding more complex grids. The results, obtained through modified IEEE test cases incorporating DC meshes along with a simplified example case, show superior results of the disjunctive DC formulation in comparison to the transportation model.