Wiktionary
n. A very small grid, especially a small power supply grid containing distributed generation of electricity
Wikipedia
Microgrid is a localized grouping of electricity sources and loads that normally operates connected to and synchronous with the traditional centralized electrical grid (macrogrid), but can disconnect and function autonomously as physical and/or economic conditions dictate. By this way, it paves a way to effectively integrate various sources of distributed generation (DG), especially Renewable Energy Sources (RES). It also provides a good solution for supplying power in case of an emergency by having the ability to change between islanded mode and grid-connected mode. On the other hand, control and protection are big challenges in this type of network configuration, which is generally treated as a hierarchical control.
Usage examples of "microgrid".
Even with the high degree of magnification possible with the microgrid screen, we can't bring out the individual ridges, but the pattern is unmistakable.