On Resistive Networks of Constant-Power Devices

This brief examines the behavior of DC circuits comprised of resistively interconnected constant-power devices (CPDs), as may arise in dc microgrids containing microsources and constant-power loads. We derive a sufficient condition for all operating points of the circuit to lie in a desirable set, where the average nodal voltage level is high, and nodal voltages are tightly clustered near one another. Our condition has the elegant physical interpretation that the ratio of resistive losses to total injected power should be small compared with a measure of network heterogeneity, as quantified by a ratio of conductance matrix eigenvalues. Perhaps surprisingly, the interplay between the circuit topology, branch conductances, and CPDs implicitly defines a nominal voltage level for the circuit, despite the explicit absence of voltage-regulated nodes.