Differential-Inspired Fault Protection for Microgrids

AC Microgrids are necessarily important for modern power systems, offering reliability, flexibility, and renewable energy integration. Yet, their dual operational modes—grid-connected and autonomous—present challenges for fault detection and protection. This paper proposes a significant harmonic content fault detection approach using high-pass filtering and transient signal analysis, integrated with differential relaying, to accurately detect and classify faults in microgrids. Unlike conventional traveling-wave-based methods relying on electromagnetic wave propagation, the proposed approach leverages high-frequency transient harmonics and a threshold-based process to isolate fault characteristics. A detailed IEEE 4-bus benchmark model in MATLAB/Simulink evaluates the methodology under diverse fault conditions, including grid-connected and islanded modes, inverter-based sources, and dynamic loads. Fault scenarios include short-circuit types such as line-to-line, line-to-ground, and three-phase faults. Results demonstrate the method's speed, accuracy, and low latency. Key contributions include a high-pass filter-based framework tailored for AC microgrids in both operational modes. This differential-inspired innovative protective approach enhances fault detection robustness, adaptability, and real-time implementation, particularly for systems with high DER penetration using Grid-Forming Inverters. By addressing critical challenges in decentralized and inverter-dominated systems, this work advances microgrid protection schemes' reliability and resilience, offering computationally efficient solutions for advanced microgrid operations.