Validation of Phasor-Domain Transmission and Distribution Co-simulation Against Electromagnetic Transient Simulation⁎

The rapid deployment of renewable energy resources has led to the widespread use of power electronics in modern power systems. As these systems transition from being dominated by large synchronous machines to increasingly incorporating inverter-based resources (IBRs), traditional transmission simulation tools that do not model the dynamics of distribution networks with a large amount of Distributed Energy Resources (DERs) are becoming inadequate. Addressing this challenge, this paper introduces a scalable phasor-domain transmission and distribution (T&D) co-simulation framework that accurately captures system dynamic behaviors under various configurations of grid-forming and grid-following inverters based on open-source software. The main focus is on the validation of this co-simulation framework against the PSCAD Electromagnetic Transient (EMT) analysis tool for a three-phase line-to-ground fault scenario. The validation results clearly demonstrate the framework’s high fidelity and a computational time speed-up of 60 to 100 times, marking a pioneering validation effort between phasor-domain and EMT simulation in T&D co-simulation research.