Distributed Robust Finite-Time Secondary Control for Stand-Alone Microgrids With Time-Varying Communication Delays

Abstract

In this paper we consider the problem of restoring the voltage for stand-alone inverter-based Microgrids despite the effects of the time-delays arising with the information exchange among the electrical busses. To guarantee that all Distributed Generators (DGs) reach in a finite-time and maintain the voltage set-point, as imposed by a virtual DG acting as a leader, we suggest a novel robust networked-based control protocol that is also able to counteract both the time-varying communication delays and natural fluctuations caused by the primary controllers. The finite-time stability of the whole Microgrid is analytically proven by exploiting Lyapunov-Krasovskii theory and finite-time stability mathematical tools. In so doing, delaydependent stability conditions are derived as a set of Linear Matrix Inequalities (LMIs), whose solution allows the proper tuning of the control gains such that the control objective is achieved with required transient and steady-state performances. A thorough numerical analysis is carried out on the IEEE 14-bus test system. Simulation results corroborate the analytical derivation and reveal both the effectiveness and the robustness of the suggested controller in ensuring the voltage restoration in finite-time in spite of the effects of time-varying communication delays.

Distributed Dynamic Event-Triggered Control for Voltage Recovery in Islanded Microgrids by Using Artificial Delays

“…In the sequel, we first characterize the electrical interaction among DGs, provided by the power transmission lines in the physical layer connecting DGs and local loads, and, then, the communication interaction due to distributed SC, enabling connection among DGs in the cyber-space. The resulting double-layer MG structure can be modeled by exploiting the graph theory as follows [3].…”

“…Assumption 2 is common in power system analysis. Interested readers may refer to [3] and [33] and references therein for more details.…”

“…Remark 1: Note that, Assumption 3 ensures the boundedness property for the term w i (t) in ( 9) [3]. It means that…”

“…Since several requirements with different time scales have to be guaranteed, a three-layers hierarchical control architecture is commonly exploited for MG control [3]. The primary control (PC) layer is usually based on droop-control, which is a communication-free method.…”

“…Along this line, cooperative control of multiagent systems (MASs) represents one of the main approaches for SC design [4]. Several distributed control strategies are introduced for the voltage regulation problem in MGs, each of them facing a specific challenge, such as finite-time convergence [3], [5], bounded uncertainties/disturbances [6], and cyber-attacks [7], [8], [9]. For instance, false data injection (FDI) attacks are considered in [8], where a distributed observer is introduced to obtain an accurate estimation of the attack signals, while a resilient controller is exploited for attacks compensation.…”