Building scale DC microgrids

The structure of both electricity supply and demand is evolving rapidly. Dispersed building-scale generation is becoming an increasingly familiar generation source and electronics based loads are ubiquitous. Given this landscape, the historic advantages of AC electricity delivery, while still strong in the high voltage realm of meshed grids and medium voltage distribution, is seeming less attractive for emerging small-scale semiautonomous systems, generally known as microgrids (or μgrids). The dominance of small-scale photovoltaics or variable frequency sources in small systems, together with the likely emergence of fuel cells and required batteries suggest a DC bus. Similarly, building loads increasingly involve DC somewhere in their electricity supply path. Given these circumstances, DC μgrids potentially eliminate conversion losses with their associated heat management problems and costs, as well as providing high quality service to loads. This paper discusses these trends and other factors that are pushing our power system towards a more decentralized paradigm, and one more reliant on DC systems.