An Overview of Anti-Islanding Protection Schemes in PV-Based Microgrids

The increasing integration of distributed energy resources (DERs), particularly photovoltaic (PV) systems, is transforming modern power systems and introducing new challenges for protection, reliability, and stability. The transition toward smart grids with bidirectional power flows has significantly changed the operating conditions under which protection systems must perform. Among the key challenges associated with DER integration is unintentional islanding, in which a DER or a group of DERs continues to energize a portion of the distribution network after disconnection from the main utility grid. If not detected and cleared within the required time, islanding may pose risks to personnel safety, power quality, equipment, and system stability. This paper presents a comprehensive review and critical analysis of islanding detection methods for PV and inverter-based DER systems, including passive, active, hybrid, and communication-based techniques. The methods are evaluated with respect to detection speed, the non-detection zone (NDZ), false-trip behavior, power-quality impact, implementation complexity, cost, and adaptability to different inverter and grid conditions. Particular attention is given to multi-inverter systems, weak and converter-dominated grids, communication and cybersecurity, and standardization and benchmarking challenges. Based on the identified limitations and research gaps, future research directions are discussed, with emphasis on AI/ML-based detection, adaptive protection, grid-forming inverters, multi-inverter coordination, PV–battery systems, weak-grid and low-inertia networks, and experimental validation. The review highlights the need for adaptive, coordinated, and intelligent islanding protection frameworks capable of ensuring reliable detection in increasingly complex inverter-dominated power systems.