01-06-2012, 01:40 PM
STRENGTHENING THE GRID
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Introduction
The continuing growth in demand for electric power, coupled with deregulation
and restructuring of electricity markets in recent years, has placed increased
demands on the electricity transmission and distribution grid in many areas of
the United States. Whereas formerly regulated utilities kept substantial reserve
margins for both generation and transmission within well-defined service areas,
the current environment, with its increasing amount of power produced and sold
in competitive markets, is characterized by increased power transfers and lower
reserve margins, leading to increased difficulty in maintaining reliability.
The Evolution of the U.S. Electricity
Transmission Grid: Transmission Constraints
This chapter summarizes transmission constraints resulting from the increased
utilization of the U.S. electricity transmission grid and from the recent increased
marketing of power. The increase in the marketing of power, in particular,
requires power transfers of a size and number well beyond those envisioned by
the designers of the current grid. HTS power technologies have properties that
could be used to address these transmission constraints. In particular, HTS cables
offer a number of benefits:
Potential Impact of HTS Cables on Grid
Reliability and Available Transfer
Capacity
This chapter describes the results of computer-generated simulations of power
flows in two specific locations of the U.S. electrical transmission grid, with and
without the presence of HTS cables. The objective of these simulations was to
quantify the impact of HTS cable use in real-world applications. We chose these
two cases to investigate because they represent two very different types of
applications, both of which address an identified U.S. transmission constraint.
The first case represents a heavily loaded urban network, the downtown Chicago
area, in which space constraints may preclude conventional transmission growth
options. The additional power-carrying capability of HTS cables may provide a
means to serve load growth by replacing, and hence upgrading, conventional
underground cables at 138 kV using existing underground conduits. The use of
the existing conduits would preclude the need for the excavation and
construction associated with adding conventional cables to increase powertransfer
capacity.