Unintentional islanding of distributed generators (DGs) endangers equipment and line workers, and the interconnection standard requires it to be detected within 2 s. This paper develops two passive detection indices based on sequence components measured at the point of common coupling (PCC). The first, RMPNSVC, is the ratio of the product of positive- and negative-sequence voltage to the product of positive- and negative-sequence current. The second, PAPSV, is the phase angle of the positive-sequence voltage evaluated every half cycle. Both were tested in MATLAB/Simulink on a distribution system with three photovoltaic (PV) DGs against zero, active and reactive power mismatch islanding, DG disconnection, line-to-ground, line-to-line and three-phase faults, and load, capacitor, inductor and motor switching. RMPNSVC separated the cases with a fixed threshold of 20 and detected islanding within 60 ms. PAPSV, with a threshold of 1.966°, detected islanding at zero mismatch in 0.10 s and in 7.82 ms at a 1.048 MW mismatch, and did not trip in any non-islanding case. No non-detection zone was found in the tested cases, and no signal is injected into the grid. The narrow threshold margin of PAPSV and the simulation-only validation are discussed.

Naveen Kumar, Prakash Narayan Tiwari, "Passive Islanding Detection for PV-Based Microgrids Using Sequence-Component Indices" International Journal of Scientific Research and Engineering Development, V9(5): Page(2190-2193) September - October 2026. ISSN: 2581-7175. www.ijsred.com. Published by Scientific and Academic Research Publishing.