The basic architecture of power distribution has changed little during the past century. Still, technologies have slowly evolved over time, and in the past decade the concept of a smart grid has emerged . Smart grids are the way of the future. Modern electricity grids are designed as centralized systems in which electricity is typically generated at large-scale power plants and then sent through long-distance transmission lines before being distributed to consumers. As a result, large power grids operate in a predictable manner: Power is generated at a central station and is sent through high-voltage transmission lines to a substation closer to consumers, where the voltage is lowered. The electricity then travels across lower-voltage lines to transformers, which convert it to an even lower voltage before it is delivered to households and businesses. This is a hierarchical, one-way transmission and communication system.