  This paper proposes a nonlinear, adaptive controller to increase the
stability margin of a direct-current (DC) small-scale electrical network
containing a constant power load, whose value is unknown. Due to their negative
incremental impedance, constant power loads are known to reduce the effective
damping of a network, leading to voltage oscillations and even to network
collapse. To tackle this problem, we consider the incorporation of a controlled
DC-DC power converter between the feeder and the constant power load. The
design of the control law for the converter is based on the use of standard
Passivity-Based Control and Immersion and Invariance theories. The good
performance of the controller is evaluated with numerical simulations.
