What is referred to as an island grid in electrical systems?

An island grid refers to a generating plant that operates independently of the larger central grid. This situation can occur during a power outage or when the main grid's stability is compromised. In such cases, the generating plant can supply power to local loads without relying on the central grid. This setup is vital for maintaining electricity supply in specific areas, especially in regions prone to outages or where grid connection is unreliable.

While other options reflect various components of electrical systems, they do not encapsulate the concept of an island grid effectively. A type of transformer, a customer-side electrical system, and large-scale energy storage do not function as standalone power sources in isolation from the main grid, which is a defining characteristic of an island grid.