A cyber-resilient multi-agent protection scheme for power distribution systems

Modern distribution networks face significant protection challenges, as conventional relays and existing multi-agent system-based relaying schemes struggle with reliable directional discrimination, high-impedance faults, busbar faults, and cyber vulnerabilities—particularly when voltage measurements are unavailable or costly. This paper proposes a fully distributed, cyber-resilient multi-agent protection scheme for power distribution systems using current-only directional overcurrent relays (DOCRs). Fault direction is determined solely by local current measurements, eliminating voltage transformers and enabling cost-effective and low-complexity implementation. Relay agents exchange only 4-digit binary messages with neighboring agents during fault suspicion, resulting in lightweight communication suitable for legacy infrastructure. The proposed scheme accurately detects both close-in line faults and busbar faults, reliably classifies fault types, and maintains robust performance across a wide range of fault resistances, including high-impedance scenarios. To ensure cyber resilience, each relay is equipped with an anomaly detection unit (ADU) that combines Principal Component Analysis Algorithm (PCAA) and Local Outlier Factor Algorithm (LOFA), enabling precise real-time detection and mitigation of false tripping cyberattacks. Under ideal measurement conditions (noise-free), the ADU achieves 100% classification accuracy, while requiring only 15% of the Multilayer Perceptron (MLP) model training time and 80% of the Isolation Forest Algorithm (IFA) model’s training time, with significantly faster real-time classification. Under degraded or noisy measurement conditions (35 dB SNR), the ADU maintains 98.5% accuracy, outperforming the MLP (96.8%) and IFA (95%) models. Extensive co-simulation integrating power system dynamics and multi-agent system logic validates fast, selective fault clearing across diverse fault types, resistances, topologies, and cyberattacks. The proposed scheme offers a practical, cost-effective, and inherently secure solution ready for real-world deployment in modern distribution networks and microgrids.