In what situation might a system operator experience islanding?

Islanding occurs when a portion of the electrical grid becomes electrically isolated from the main power network while still being energized by local generation sources. This situation typically arises during fault conditions that disconnect a generation source from the utility grid.

When a fault occurs—such as a short circuit or other disturbances—the protective systems in place may isolate a section of the grid to prevent damage or instability. If there are local generators in that isolated section, they may continue to supply power even though they are no longer connected to the larger grid. This maintains voltage and frequency locally, leading to the phenomenon known as islanding, where the section operates independently from the rest of the grid.

Low demand periods and routine maintenance activities generally wouldn't create the necessary conditions for islanding, as these scenarios don't involve fault conditions that would lead to separation from the grid. Similarly, simply increasing interconnections typically helps to enhance stability and reduce the likelihood of islanding. Thus, the most accurate situation in which an operator would experience islanding is during a fault that separates a generation source from the rest of the grid.