LAUSR

Abstract Hierarchical control based on master–slave structures helps overcome the limitations of the droop control-based DC distribution system (DCDS), especially concerning high bus impedance and bus regulation, without compromising on the two key features of the latter, namely the communication independency and the expandability. As an in-depth research was necessary to validate the meritorious features of the master–slave based hierarchical control, we investigated the new method in the present study using small-signal modeling of the interface units (IU) of the three sub-systems, renewable energy sources (RIU), energy storage systems (SIU), and the grid (GIU). Furthermore, to eliminate the likelihood of an instability owing to the integration of the sub-systems, we applied Cho’s stability criterion, which compares the impedances of the output and the constant power load (CPL) for securing the stability of the DCDS. Subsequently, we validated the hierarchical control-based DCDS for the conditions such as steady-state, long-time operation, and master failure using a 1-kW hardware implementation that comprised the three interface units, a photovoltaic simulator, and a battery pack. The system parameters optimized using the experiments provide the possibility for designing large-scale DCDS systems based on the hierarchical method.