Advancements in Co-Simulation Techniques in Combined Transmission & Distribution Systems Analysis

Common practice in transmission and distribution (T&D) systems analysis has been to treat them independently by decoupling those at the point of common coupling (PCC). With the large amount of distributed energy resources (DER) being added in distribution networks, the interactions between T&D systems at PCC produce unacceptable errors. This study discusses an alternate approach for the combined T&D systems analysis using co-simulation technique. The proposed framework couples the analysis of the two systems by iteratively exchanging the power flow variables at the PCC. The approach is implemented for an IEEE 9-bus transmission test system coupled with the IEEE 13-bus distribution test system and the analysis is validated against an equivalent stand-alone combined T&D system model.