Simplified Short Circuit Current Simulation in LVDC Microgrids

For the increasing integration of dc-based sources and loads, low-voltage dc (LVDC) microgrids offer improved efficiency and reliability. However, protection remains a major challenge due to the distinct characteristics of dc fault currents, such as the absence of zero crossings of the current. To develop and evaluate new protection concepts, accurate simulation models are essential. While detailed switching models of the power converters provide high accuracy, they are computationally intensive. This paper investigates two simplified modeling approaches of the dual-active bridge (DAB) converter, an average model and a passive model approach, and compares their short circuit current (SCC) simulation results to traditional switching model results for various fault locations. The comparison focuses on both, simulation accuracy and execution time. The average model shows good agreement with the switching model in terms of peak current and overall current levels, although it deviates in dynamic behavior. The passive model exhibits larger inaccuracies. Both simplified models, however, enable substantial reductions in execution time, highlighting their potential for use in large-scale simulations and real-time applications.