Validation of Dynamic Transmission and Distribution Analysis in the Presence of Distribution Systems

This paper conducts a comparative study to investigate the accuracy of distribution lumped impedance model under fault conditions. A transmission-distribution (T&D) co-simulation algorithm is used to precisely provide asymmetrical analysis for three-phase faults in the asymmetrical distribution grid and their impact on the symmetrical transmission network. Next, the distribution system is replaced by its equivalent impedance and dynamic simulation is conducted under the faulty condition using a positive sequence dynamic simulator. Also, the North American Electric Reliability Corporation DER_A model (NERC-2018) is deployed at the transmission level to model the dynamics of the inverter-based resources. The study shows that the distribution impedance model can result in a different dynamic response than that of the T&D co-simulation, utilizing a meticulous distribution model, under distribution three-phase faults.