Secondary Defense Strategies of AC Microgrids Against Generally Unbounded Attacks

TL;DR

The paper tackles the problem of securing AC microgrids against generally unbounded attacks injected into the secondary control inputs. It introduces fully distributed adaptive defense strategies that add compensational signals with sparsely communicating neighbors, and provides Lyapunov-based proofs that the closed-loop system achieves uniformly ultimately bounded ($\mathrm{UUB}$) convergence for frequency regulation and voltage containment, while preserving active power sharing. The approach extends beyond existing bounded-attack models by requiring only bounds on the $\gamma$-th derivative of the attack signals and demonstrates provable resilience via Theorems 1–2, with ultimate bounds tunable through adaptation gains. Validation on a modified IEEE $34$-bus benchmark with four inverter-based DERs confirms robust performance under unbounded attacks, load steps, and communication link failures, highlighting practical applicability and scalability for real microgrids.

Abstract

This paper develops a fully distributed attack-resilient secondary defense strategies for AC microgrids, addressing more generally unbounded attacks on control input channels than those addressed in existing literature. The secondary control of local inverter includes consensus-based voltage and current regulators utilizing relative information from neighboring inverters. This distributed control approach relies on localized control and a sparse communication network, making it susceptible to malicious cyber-physical attacks that can impair consensus performance and potentially destabilize the overall microgrid. In contrast to existing solutions that are limited to addressing either bounded faults, noises or unbounded attacks with bounded first-order time derivatives, we aim to surpass these constraints and enhance the defense capabilities of counteracting cyber-physical attacks by enabling the AC microgrids adopting the proposed strategies to withstand a much wider range of unbounded cyber-attack signals. Fully distributed attack-resilient secondary defense strategies are developed for AC microgrids to counteract the detrimental effects of generally unbounded attacks on control input channels. Rigorous proofs using Lyapunov techniques demonstrate that the proposed defense strategies accomplish the uniformly ultimately bounded convergence on frequency regulation and achieve voltage containment and active power sharing simultaneously for multi-inverter-based AC microgrids in the face of generally unbounded attacks. The proposed defense strategies are validated on a modified IEEE 34-bus test feeder benchmark system incorporating four inverter-based DERs.

Figures (9)

• Figure 1: A networked multi-inverter system under actuator attacks.
• Figure 2: Communication layer among inverters, and the proposed attack-resilient secondary defense strategies for an inverter.
• Figure 3: Cyber-physical microgrid system: (a) Communication graph topology among four inverters and two leaders (references), (b) IEEE 34-bus system with four inverters.
• Figure 4: Performance of the conventional secondary control under unbounded attack signals: frequency performance, active power of inverters and voltage performance.
• Figure 5: Performance of the proposed fully distributed attack-resilient secondary defense strategies under unbounded attack signals: frequency performance, active power of inverters and voltage performance.