Types of Microgrids

Sendai Microgrid, Tohoku Fukushi University, Japan (Customer microgrids or true microgrids example)
Mannheim-Wallstad, Germany (Utility or community micro grids or milligrids example)
Kyotango, Kyoto Prefecture, Japan (Virtual microgrids example)
Huatacondo, Tarapacá Region, Chile (Remote power systems example)

Two key types of microgrids can be distinguished, and two other related types of power systems apply very similar technology.

  1. Customer microgrids or true microgrids (µgrids) are self-governed, and usually downstream of a single point of common coupling (PCC). Many of the most well known demonstrations are of this type. They are particularly easy to imagine because they fit neatly into our current technology and regulatory structure. Just as a traditional customer has considerable leeway in the operation of the power system on its side of the meter, so the restrictions on the nature of a µgrid are relatively loose. For this reason, one would expect much of the early deployment of microgrid technology to be of this type.

  2. Utility or community microgrids or milligrids (mgrids) involve a segment of the regulated grid. There are also existing well known examples. While technically, they not be different from µgrids, they are fundamentally different from a regulatory and business model perspective, primarily because they incorporate traditional utility infrastructure. The corollary of this feature is that utility regulation comes much more significantly into play. In other words, any mgrid must comply with existing utility codes or accommodation must be made in the code.

  3. Virtual microgrids (vgrids) cover DER at multiple sites but are coordinated such that they can be presented to the grid as a single controlled entity. Very few demonstrations of vgrids exist, but they have been proposed in the literature. Note that to be consistent with the definition above, the system must be able to operate as a controlled island or coordinated multiple islands.

  4. Remote power systems (rgrids) are obviously not able to operate grid-connected, isolated power systems involve similar technology and are closely related. So close that from a research point of view, they are commonly described as microgrids.