ABSTRACT
When electricity was first made available in the late nineteenth century, it was through central stations serving a group of nearby customers. Generation and distribution were localized, and long-distance transmission was not yet necessary. As demand for electricity service increased, distribution networks expanded in capacity and geography. Systems once isolated from one another were becoming interconnected. Out of this emerged the basic operating structure of the grid still in place today:
Large geographically dispersed power plants generate electricity 1 at low voltage levels.
The voltage is then stepped up via transformers in transmission substations. Electric utility interconnection overview. (Courtesy of the Advisory Board of the Utility Executive Course, University of Idaho, Moscow, ID.) https://s3-euw1-ap-pe-df-pch-content-public-u.s3.eu-west-1.amazonaws.com/9781351228480/9cbbb7f0-8e29-4dee-9662-f3a3119395a5/content/fig1_1.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/>
The electricity at high voltage levels is transmitted over long distances on interconnected transmission lines to distribution substations, where transformers step down the voltage 2 to low levels.
The electricity at low voltage levels is then distributed over relatively short distances via a network of lines using smaller transformers, which step the voltage down further to levels safe and appropriate for customers—homes and businesses.
