A cumulative sum-based protection method for inverter-interfaced microgrids

This paper presents a MCUSUM-based protection scheme for enhancing fault detection in high-IBR microgrids, specifically considering both grid-following and grid-forming inverters in the modeling, analysis, and testing phases. While previous works have focused on overcurrent, impedance-based and differential protection schemes, they often struggle with low short-circuit currents and variable power factors during faults, limiting their effectiveness in high-IBR environments. The proposed approach enables rapid direction change detection and coordinated relay operation through control flag exchanges. Real-time experiments using the Typhoon platform validate the method's effectiveness across low voltage ride-through (LVRT) grid codes from different countries. Results demonstrate reliable fault detection in both grid-connected and islanded modes, effectively managing various fault types and resistance levels under acceptable noise levels. The proposed method not only addresses the limitations of existing protection strategies but also showcases adaptability in diverse operational scenarios, making it a practical solution for enhancing the reliability of microgrid systems with high IBR penetration.