Tertiary load voltage control in an interconnected DC microgrid with energy hub

This paper presents a hierarchical control of an interconnected DC microgrid system. In an interconnected DC micrgrid, power injections and absorptions at different buses can cause significant voltage deviations at load terminals. Even though droop control at the primary level aids in sharing of load among the converters, it introduces load dependent voltage drop in the system. To overcome this, voltage restoration can be provided at the voltage controlled buses. However, secondary voltage control at different buses cannot ensure voltage quality at critical load buses. This paper proposes a tertiary load voltage control utilizing the coordination among different voltage controlled buses to set their references such that the load voltage deviation is minimized. Based on the present state of the network, the tertiary level runs an optimization algorithm and reroutes the power distribution in the network. This redistribution of power in turn mitigates the load voltage deviations. The proposed control topology is verified using simulation results for a four-bus interconnected DC microgrid system.