Observer-Based Discontinuous Communication in the Secondary Control of AC Microgrids

TL;DR

This work tackles the high communication burden of networked AC microgrid secondary control by introducing an observer-based event-driven framework that estimates unshared states and transmits only at event instants. The core approach combines a full-state Luenberger observer with an event-triggered mechanism, guaranteeing a bounded estimation error and proving Zeno-freeness. The method is presented as universally applicable to any communication-based secondary controller and is validated in a three-DG, 311 V microgrid via MATLAB/Simulink, achieving substantial reductions in data exchange while preserving voltage regulation and reactive-power sharing. Key contributions include the observer design via $A S + S A^{T} - S C^{T} V^{-1} C S + W = 0$, the event-triggering rule, and the demonstration that only $v_{cd}$ needs to be exchanged under all-to-all averaging, with extensions to packet loss, delays, and measurement noise discussed for future work.

Abstract

This paper proposes an observer-based event-driven approach to decrease the overuse of communication networks. The suggested approach aims to estimate the required data for sharing between units in line with as much communication reduction as possible. In other words, the proposed approach effectively determines which state variables should be shared (observer concept) among the units during specific time intervals (event-triggered concept). This strategy significantly reduces the overall communication load. It is shown that the estimation error remains bounded and Zeno behavior, characterized by an endless number of transmissions occurring within a limited time frame, does not occur. The proposed methodology can be systematically applied to any communication-based secondary controller in alternating current (AC) microgrids. Simulation results demonstrate a high degree of precision in estimating the states under the proposed approach. Also, the secondary controller performance under the proposed method is evaluated in MATLAB/Simulink environment.

Figures (10)

• Figure 1: The general control diagram of AC microgrids for a DG.
• Figure 2: The frame of the suggested event-based strategy.
• Figure 3: Event-triggered observer-based secondary controller.
• Figure 4: Diagram of the considered AC microgrid.
• Figure 5: DGs' filter current and their estimations in $d$ frame.