The traditional electric power generation and delivery model builds large, centrally located power plants (essentially hubs) and surrounds these with major electrical load centers.
The electric power grid brings power to its users from the plant. There are two infrastructures. The first are high voltage transmission systems that carry electricity from the power plants and then transmit the electricity for hundreds of miles. The second are the lower voltage distribution systems that draw electricity from the transmission lines to then distribute the drawn electricity to individual customers.
While high voltage is used for transmission lines in an effort to minimize electrical losses, it is not practical for use in distribution lines. The interface between high and low voltage is the electrical substation that uses transformers that decrease the transmission voltages to the lower voltages that are used in the distribution systems. Transformers are also placed along the distribution lines to further decrease the voltage to 120V or 240V, which is the voltage that is practical for household use. Substations use electrical switchgear and circuit breakers to protect both the transformers and the transmission system from any electrical failures on the distribution lines. Circuit breakers are also placed along the distribution lines in an effort to locally isolate any electrical problems (e.g., such as short circuits that can be caused by downed power lines). Outside of distributed generation pilot projects there have been no major changes in the electrical grid in recent years. It is the Smart Grid idea that is drawing attention to the electrical infrastructure and the necessity for change. [1]
