Extended Dissipative Scalable Control for AC Islanded Microgrids

In this study, an innovative extended dissipative scalable control approach is proposed for monitoring islanded microgrids (ImGs), which has the advantage of flexibility for adding and removing distributed generation units (DGUs). Firstly, an arbitrary topology is developed in order to circumvent the connected constraints of subsystems in previous results. Secondly, the impact of subsystem indexing on total subsystem communications is investigated during the execution of scalable control algorithms, and an optimizable cost function is created to determine the cost related to subsystem indexing. Then, by using Lyapunov stability theory, several sufficient conditions under the subsystem-level are established to ensure the studied system are globally exponentially stable with the desired extended dissipative performance, which can guarantee that when adding DGUs in ImGs, only directly connected controller gains needed to be designed, and when removing DGUs in ImGs, no controller gains needed to be redesigned, that is, plug-and-play performance is achieved. Finally, the considered ImGs containing three DGUs and a numerical example are presented to demonstrate the effectiveness of the proposed control approach.

I. Introduction

Island microgrids (ImGs) are self-contained microgrids made up of numerous distributed generation units (DGUs) that are meant to run securely and reliably without being connected to the main grid [1], [2], [3], [4], [5]. Among them, the plug-and-play function of DGUs, as one of the main vital issues, has attracted widespread attention due to the inherent discontinuity of renewable energy [6]. To address this issue well, the quasi-stationary line approximations method is frequently used, then electrical couplings among DGUs can be described by a graph Laplacian matrix [7]. Using the aforementioned linear approximation, stability analysis, current sharing and voltage balancing, voltage and frequency regulation for ImGs are explored, see [8], [9], [10], [11], and references therein.