22-08-2012, 02:49 PM
GOVERNMENT SERIES Smart Grid
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Introduction
The electric grid delivers electricity from points of generation to consumers, and the electricity
delivery network functions via two primary systems: the transmission system and the distribution
system. The transmission system delivers electricity from power plants to distribution substations,
while the distribution system delivers electricity from distribution substations to consumers. The grid
also encompasses myriads of local area networks that use distributed energy resources to serve local
loads and/or to meet specific application requirements for remote power, municipal or district power,
premium power, and critical loads protection.
The concept of a “smart grid” lacks a standard definition but centers on the use of advanced technology
to increase the reliability and efficiency of the electric grid, from generation to transmission to distribution.
However, the smart grid does not necessarily replace the existing infrastructure, most of which was
installed in the 1970s.
Electric Power Transmission: Background and
Policy Issues
Introduction and Organization
This report discusses electric power transmission and related policy issues. Transmission is a
prominent federal issue because of a perceived need to improve reliability and reduce costs,
transmission’s role in meeting national energy goals (such as increased use of renewable
electricity), and the potential efficiency advantages of “smart grid” modernization. Proposals
before the 111th Congress for changing federal transmission law and regulations to meet these and
other objectives include S. 539, the Clean Renewable Energy and Economic Development Act,
introduced on March 5, 2009; and the March 9, 2009, majority staff transmission siting draft of
the Senate Energy and Natural Resources Committee (the “Senate Energy Majority Draft”).1
Physical and Technical Features of the Power System
• Generating plants produce electricity, using either combustible fuels such as coal,
natural gas, and biomass; or non-combustible energy sources such as wind, solar
energy, and nuclear fuel.
• Transmission lines carry electricity from the power plant to demand centers. The
higher the voltage of a transmission line the more power it can carry. Current
policy discussions focus on the high voltage network (230 kilovolts (kV) rating
and greater) used to move large amounts of power long distances.2
• Near customers a step-down transformer reduces voltage so the power can use
distribution lines for final delivery.3