A Scalable Port-Hamiltonian Approach to Plug-and-Play Voltage Stabilization in DC Microgrids

Exponential Stability and Local ISS for DC Networks

“…This objective can be equivalently addressed by regulating the charge to the set-point q = CV . Note that in this letter we focus only on voltage regulation, which is vital to guarantee the safety of the network and a proper functioning of the connected loads [2]- [12]. The achievement of also current (or power) sharing (see for example [17] and the references therein) is beyond the scope of this letter and left as a future research work.…”

“…However, these works do not include P-loads and, some of them, neglect the network or consider it purely resistive. In order to address the voltage destabilizing effect of the negative incremental impedance introduced by P-loads, several controllers have been proposed in the literature, including energy-based approaches [9]- [12]. More specifically, in [9], the authors provide a suitable port-Hamiltonian (pH) framework [13] to model electrical circuits including constant ZIP-loads and investigate their shifted passivity properties.…”

“…In [11], the authors establish new passivity properties leading to the design of a voltage controller that is robust with respect to constant ZIP-loads. In [12], a systematic and constructive design based on the pH framework is proposed. We note that all these works provide stability guarantees only in presence of constant load components, while loads are in practice time-varying.…”

“…The main contributions of this letter can be summarized as follows: C.1 Differently from [10], we present a unified framework for control design and analysis whilst maintaining a simple control structure. C.2 Differently from [12], where the control law comprises a model-based disturbance compensation that, if omitted, compromises the performance (see [12,Remarks 3 and 4]), we consider unknown load components. C.3 Differently from [3]- [12] and other relevant works on the topic, we prove LISS of the closed-loop system with respect to unknown time-varying disturbances acting on any of the state dynamics.…”

“…C.2 Differently from [12], where the control law comprises a model-based disturbance compensation that, if omitted, compromises the performance (see [12,Remarks 3 and 4]), we consider unknown load components. C.3 Differently from [3]- [12] and other relevant works on the topic, we prove LISS of the closed-loop system with respect to unknown time-varying disturbances acting on any of the state dynamics. This could represent, for example, a time-varying component of a supplied ZIP-load.…”