Intelligent power grids are classified in terms of their size as supergrids, smart grids and microgrids. Microgrids are self-sufficient distribution networks with regional boundaries to which smaller power generators, energy storage systems and consumers are directly connected.
Microgrids are connected to the nationwide smart grids that provide national power generation and distribution. Supergrids are superordinate to these. These are high- voltage grids that span countries and continents.
Super grids connect national and international power plants, wind turbines and large photovoltaic systems. They transmit enormous amounts of electrical energy over high-voltage and extra-high-voltage grids using high-voltage direct current transmission. Smart grids are directly connected to super grids, into which they can feed energy or from which they can draw energy.