Original title: Quantifying the Unintentional Islanding Risk: A Comparative Study on Active Distribution Network
Harshit Nayak, Edoardo Daccò, Jose Luis Rueda Torres, Davide Falabretti · September 2026
As renewable energy connects to power grids through inverters, parts of a network risk forming an accidental "island." This happens when a local area disconnects from the main grid but keeps running on its own, which can cause safety and stability issues. Researchers modeled a medium-voltage network to see how different power sources affect this risk. They tested traditional synchronous generators and grid-following converters under two control modes. They found that if generators run at a fixed power output, the island fails quickly. Its frequency and voltage drift past safety limits within tens of seconds, shutting it down. But if generators actively regulate their voltage and frequency, they can keep the accidental island powered indefinitely without tripping standard protections, no matter the system's inertia.
Picture a spare room in a house with its own thermostat and heater. Usually the central furnace keeps it warm. If the room gets accidentally cut off from the ductwork, a heater set to a fixed level will let the temperature drift, and the cold monitor will eventually trip. But if the heater adjusts itself to hold a steady temperature, the room stays comfortable and the monitor never goes off. In this paper, the room is a segment of an electrical grid, and the heater is a generator that regulates its output.
If a section of the grid keeps running on its own after an outage, repair crews could assume it's dead and work on live lines. This study shows that simply having generators regulate frequency and voltage makes that danger last forever, so protection systems need to adapt.
The abstract doesn't state explicit limitations, but it focuses on a single MV network segment with one type of grid-following converter and synchronous generators. It does not cover grid-forming inverters, other control modes, or protection coordination beyond the thresholds mentioned.
Ask anything about this paper. Answers come from its abstract, and say so when the abstract doesn't cover your question.
Quantifying the Unintentional Islanding Risk: A Comparative Study on Active Distribution Network — Harshit Nayak, Edoardo Daccò, Jose Luis Rueda Torres et al.
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.