Plug-and-Play Robust Voltage Control of DC Microgrids

Abstract

Abstract-The purpose of this paper is to explore the applicability of linear time-invariant (LTI) dynamical systems with polytopic uncertainty for modeling and control of islanded DC microgrids under plug-and-play (PnP) functionality of distributed generations (DGs). We develop a robust decentralized voltage control framework to ensure robust stability and reliable operation for islanded DC microgrids. The problem of voltage control of islanded DC microrgids with PnP operation of DGs is formulated as a convex optimization problem with structural constraints on some decision variables. The proposed control scheme offers several advantages including decentralized voltage control with no communication link, transient stability/performance, plug-and-play capability, scalability of design, applicability to microgrids with general topology, and robustness to microgrid uncertainties. The effectiveness of the proposed control approach is evaluated through simulation studies carried out in MATLAB/SimPowerSystems Toolbox.

Distributed Averaging Control for Voltage Regulation and Current Sharing in DC Microgrids

“…The aforementioned careful coordination is foremost needed to ensure that voltages at the loads are around desired values and to ensure that providing power to the network is shared fairly among the various sources [7]- [11]. A popular approach to obtain this fair sharing, is to design controllers that aim for (proportional) current sharing, wherein the total current that has to be generated is (proportionally) allocated to the various sources.…”

Robust Passivity-Based Control of Boost Converters in DC Microgrids⋆

“…However, only constant impedance loads are considered, the network dynamics are neglected and in [15] the load resistance is assumed to be known. In [16] and [17], Plug-and-Play voltage controllers are proposed. More precisely, the controller designed in [16] is robust with respect to load uncertainties.…”

A Port-Hamiltonian Approach to Plug-and-Play Voltage and Frequency Control in Islanded Inverter-Based AC Microgrids

“…> 0, and P Li > 0. For voltages below 0.7V 0 , the corresponding Z load forms a special case of the subsequent analysis withĪ Li = 0 and P Li = 0 in (7). Consequently, it is not considered explicitly.…”

“…At present, the voltage stabilization is structured hierarchically with the basic control task being performed by local VSC controllers at primary level [3] [4][5] [6]. A further challenge of integrating a high share of DGUs is their varying availability due to the intermittent nature of most renewable energy sources, which can in worst case lead to plug-in and -out operations [7].…”

“…Although the resulting overall control simultaneously achieves offsetfree voltage stabilization and current sharing (see [9] and references therein), it comes at the cost of some form of communication and limited plug-and-play capability, and thus is outside the scope of this paper. An alternative approach to decentralized, primary voltage control is proposed in [1] and for example extended in [7] and [8]. It is based on quasi-stationary approximations of line dynamics which are only valid in low-voltage networks.…”