Active damping of a DC network with a constant power load: an adaptive observer-based design

Abstract

This paper proposes a nonlinear, output feedback, adaptive controller to increase the stability margin of a direct-current (DC), small-scale, electrical network containing an unknown constant power load. 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 overcome this drawback, we consider the incorporation of a controlled DC-DC power converter in parallel with the constant power load. The design of the control law for the converter is particularly challenging due to the existence of unmeasured states and unknown parameters. We propose a standard input-output linearization stage, to which a suitably tailored adaptive observer is added. The good performance of the controller is evaluated with numerical simulations