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Electric power networks are divided into transmission and distribution networks. Transmission lines move electric power between generating facilities and substations, usually in or near population centers. From substations, power is sent to users over a distribution network. A transmission line might move power a few miles or hundreds of miles.
An entity that generates power does not have to own power transmission lines: only a connection to the network or grid. The entity then pays the owner of the transmission line based on how much power is being moved and how congested the line is.
Some power generating entities join a group which has shared ownership of transmission lines. These groups may include investor-owned utilities, government agencies, or a combination of these.
Since prices to move power are based on congestion in transmission line networks, utilities try to charge customers more to use power during peak usage (demand) periods. This is accomplished by installing time-of-use meters to recover wheeling costs.