A Connectively Stable and Robust DAPI Control Scheme for Islanded Networks of Microgrids

TL;DR

The paper tackles robust secondary-level frequency and voltage control for islanded networks of microgrids (NMGs) under renewable variability and cyber-physical disturbances. It introduces a connective-stability based robust DAPI controller augmented with the invariant-ellipsoid disturbance rejection, and frames the design as an LMI problem to compute connective-strength bounds and decentralized gains. The approach yields improved robustness and resilience against cyberattacks and topology perturbations in a 3 MG, 5 DER MATLAB/Simulink testbed, at the cost of somewhat slower power sharing. Practically, the work provides a distributed, topology-robust framework for islanded NMGs that can maintain near-nominal frequency and voltage under adverse conditions, guiding future hierarchical control refinements and energy-reserve quantification across control layers.

Abstract

The transition towards clean energy and the introduction of Distributed Energy Resources (DERs) are giving rise to the emergence of Microgrids (MGs) and Networks of MGs (NMGs). MGs and NMGs can operate autonomously in islanded mode. However, they face challenges in terms of secondary level frequency and voltage regulation, due to the variable nature of Renewable Energy Sources (RES) and loads. Distributed-Averaging Proportional-Integral (DAPI) control has been proposed in the literature for distributed frequency and voltage control of droop-controlled DERs, but it is not robust to operational or structural perturbations. To address this, we propose a robust DAPI frequency and voltage control scheme that ensures robustness using the concept of connective stability, along with the invariant ellipsoid technique for disturbance rejection. Simulation of an NMG model in MATLAB\textsuperscript{\textregistered}/Simulink\textsuperscript{\textregistered} consisting of 3 MGs and 5 DERs validates the effectiveness of the proposed method, and demonstrates that it can successfully mitigate the effects of major disturbances such as cyberattacks.

Figures (11)

• Figure 1: The DER block diagram with primary level (droop) and secondary level (DAPI) control.
• Figure 2: The proposed control scheme.
• Figure 3: The NMG model consisting of 3 MGs and 5 DERs.
• Figure 4: From top to bottom: DER active power, frequency, reactive power and voltage using the base DAPI scheme from 0 to 10 seconds (DAPI activation).
• Figure 5: From top to bottom: DER active power, frequency, reactive power and voltage using the proposed scheme from 0 to 10 seconds (DAPI activation).