Active Damping of a DC Network with a Constant Power Load: An Adaptive Observer-based Design

Abstract

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.

An Adaptive Observer-Based Controller Design for Active Damping of a DC Network With a Constant Power Load

“…To introduce and support our methodology, we enlist the following remarks [10]. R1: Observe from P2 that if the capacitance C 1 is not big enough, then, in order to maintain the system's stability, the power extraction from the CPL must be strictly smaller than the upper bound for existence of equilibria given in (2).…”

“…From [10], we enumerate the properties of this network. P1: The system (1) has two real equilibria if and only if…”

“…The parameterization that we propose in ( 7) implies a more involved algebraic expression for the damper's power losses; nonetheless, with an appropriate selection ofū, these losses can be made considerable inferior with respect to the approach adopted in [10]. The effectiveness of this choice is illustrated in the experimental results that are reported in Section VI.…”

“…The stabilization problem addressed in this article, as well as the proposed controller topology, have previously been studied in [10], where a full state-feedback adaptive passivity-based control has been proposed. As discussed in Section IV-A, besides the impractical requirement of full state measurement, the approach adopted in that paper suffers from significant energy efficiency drawbacks, which renders the proposed controller design practically unfeasible.…”

“…Caveat Emptor: A preliminary version of this work has been reported in the conference paper [9]. In contrast to [9], in the present work, we include the proofs of all propositions and add more detailed simulations and experimental results.…”