By John Kemp
LONDON, April 5 Smart meters are the most
visible part of the power industry's attempt to upgrade the
electricity network to cope with rising consumption and the
integration of renewable sources of generation such as wind and
The U.S. federal government is spending hundreds of millions
of dollars to support the roll out of smart meters that will
enable more variable power pricing linked to time of use (TOU)
or peak demand to encourage ordinary households and small
businesses to limit their electricity use when demand is
greatest and help manage pressure on the grid.
Increasing the amount of "demand-side response" is crucial
to improving flexibility and ensuring the grid can cope with the
unpredictable output of intermittent power sources such as wind
and solar, as well as small-scale distributed generation by
households and businesses themselves selling power back into the
network at irregular times.
But the smart grid is about much more than just smart
meters. The Smart Grid Investment Grant (SGIG) programme
established by the American Recovery and Reinvestment Act (ARRA)
is also funding the deployment of 877 high-frequency phasor
monitoring units (PMUs) linked to satellite communications and
the global positioning system.
The aim is to improve the robustness and reliability of the
transmission grid and prevent a repeat of the cascading power
failures that rolled across the north-eastern United States and
parts of Canada in 2003.
In less than five minutes on the afternoon of Aug. 14, 2003,
a local problem in the Cleveland-Akron area of Ohio that had
been rumbling all afternoon spread like a tidal wave across the
network, shutting down 508 generating units at 265 power plants,
including emergency stoppages of 10 nuclear stations, as power
surged uncontrollably around the grid. It left 50 million people
without electricity, some for as long as four days.
The official report blamed tree growth for failure on five
transmission lines, coupled with a computer system failure and
poor communications and operating practices by grid managers for
starting a power failure that then spiralled as grid managers
lost control ("Final Report on the August 14 2003 Blackout"
But it was only the largest and most recent in a series of
massive outages, including another blackout in the north-east in
1965 which left 30 million people without power for 13 hours; an
outage affecting 9 million in New York City in 1977; and
disturbances on the West Coast in 1982 and twice in 1996 leaving
millions without power each time.
North America's power network, built by a patchwork of local
utilities, has always been less robust and more prone to
wide-area failures than the more centralised networks common in
the United Kingdom and Western Europe.
But the official report into the 2003 incident identified a
series of developments that have increased stress on the grid
and risked undermining reliability. Marketisation has led to the
proliferation of many more short-term power contracts, the entry
of a host of smaller generators, often with less experience of
The report also blamed the erosion of unused transmission
capacity, rising system throughput, moving (wheeling) power over
long distances, and the declining willingness of utilities to
make investments in transmission reliability that do not
increase revenues. (See page 104 for a list of the changing
industry conditions that have affected reliability).
The report ended with 46 recommendations for improving the
system's resilience against cascading failures, as well as
cyber-attacks by terrorists or foreign powers. The industry has
since made significant progress implementing some of them,
especially those linked to operating procedures.
But integration of a substantial share of renewables will
make the challenge harder. Grid controllers will have to deal
with an increased share of intermittent, unpredictable
generation; the need to move power across even longer greater
distances (from the windy Midwest to the power hungry north-east
for example); and back it up with gas-fired generation at short
notice; all the while preventing congestion.
The grid is only as strong as its weakest link and its
capacity to react to failures once they happen in an orderly
Intermittent and distributed generation will make grid
management far more complex. Monitoring power flows across the
network and detecting disturbances and failures quickly enough
to react will become even more essential to prevent cascading
BEAM ME UP, SCOTTY
The hoped-for solution to grid instability is something
called the North American SynchroPhasor Initiative (NASPI),
which sounds like something out of Star Trek but is in fact a
collaboration between the federal government and industry to
improve grid monitoring and control by using modern
More than 500 phasor monitoring units have so far been
installed across the transmission network to take precise
measurements of frequency, voltage and other aspects of power
quality on the grid up to 30 times per second (compared with
once every four seconds using conventional technology).
Units are synchronised using GPS to enable users to build up
a comprehensive real-time picture of how power is flowing across
the grid (www.naspi.org/Home.aspx and).
It is a scaled-up version of the monitoring system developed
by the University of Tennessee's Power Information Technology
Laboratory using inexpensive frequency monitors that plug into
ordinary wall sockets.
Tennessee's FNET project provides highly aggregated data to
the public via its website.
The systems being developed under NASPI provide a much finer
level of detail that will reveal congestion and disturbances on
individual transmission lines and particular zones so that grid
managers can act quickly to restore balance or isolate failures
Data on its own will not ensure greater stability. Better
grid operations and practices will be essential to make use of
it. But it is a vital first step and is essential if the system
is going to integrate more renewables - and maybe eventually
plug-in electric vehicles - without increasing chaos on the
system and more blackouts.