Hierarchical Self-Commissioning Control of Grid-Supporting Boost Converters with Nonlinear Loads

Collective voltage stability and efficient load-sharing are critical objectives of grid-supporting distributed generation units in DC islanded microgrids. This paper proposes a hierarchical self-commissioning control architecture which offers plug-and-play and fully scalable design features. First, passivity theory is used to provide an explicit inequality set of control gains for decentralised state-feedback controllers at the primary control level. This set is completely independent of global system parameters and microgrid topology and is shown to guarantee collective stability of the whole microgrid comprised of DC-DC boost converters, RL power lines and linear/nonlinear loads. Second, the proposed primary controller is cascaded with distributed consensus-based secondary controls in order to perform voltage balancing and equal load-sharing. Asymptotic stability of the secondary control level is proven using a unit-gain approximation of the primary level. Finally, the architecture is evaluated using a single bus-connected topology and plug-and-play operations.