  In this paper we present new (stochastic) passivity properties for Direct
Current (DC) power networks, where the unknown and unpredictable load demand is
modelled by a stochastic process. More precisely, the considered power network
consists of distributed generation units supplying ZIP loads, i.e., nonlinear
loads comprised of impedance (Z), current (I) and power (P) components.
Differently from the majority of the results in the literature, where each of
these components is assumed to be constant, we consider time-varying loads
whose dynamics are described by a class of stochastic differential equations.
Finally, we prove that an existing distributed control scheme achieving current
sharing and (average) voltage regulation ensures the asymptotic stochastic
stability of the controlled network.
