Pacific Northwest National Laboratory in
the US is promoting "Grid Friendly Appliances" which are
similar to dynamic demand appliances being promoted here in the
UK. The appliances utilise the AC frequency as an idicator of power
imbalance and switch off for a pre-programmed period at times of
power system stress. The system comes under their wider label of
GridWise Alliance has also
been established, a US-based group which promotes technologies to
help intelligent demand management of electricty.
Ltd, a UK-based company which specialises in the integration
of renewable electricity, has developed an "intelligent load controller"
for use on small power grids that have very high penetrations of
intermittent renewable generation. Frequency control is a challenging
task on such "micro-grids". The Econnect devices monitor system
frequency and use fuzzy logic to decide when to switch resistive
loads (such as space and water heating) in order to maintain frequency
is developing a suite of demand-side technologies aimed at helping
to manage electricity grids. These include for example a proprietory
dynamic demand device called the "ResponsiveLoad Controller"
which uses the AC frequency to affect the probability of switching,
and the "Time-Shifting Controller", both for use with
Martin Energy Limited promotes the concept
a networked system that can coordinate the switching of many diverse
loads (or standby generators) belonging to many different "energy
partners" in order to create one large "flexible"
and controllable "load".
In the UK, the National
Grid Company (NGC) has introduced a special tariff which
rewards large-scale consumers who agree to provide a limited form
of frequency response. Called Frequency Response by Demand Management
(FCDM), the scheme involves the placing of certain large loads behind
frequency-sensitive relays which isolate the load when the frequency
falls below a pre-set level, often 49.7 Hz.
Oak Ridge National Laboratory in the United
States is carrying out research for the US Department of Energy
on the use of controllable loads to increase system security. The
proposal is for a pager-controlled switch, attached to consumers
such as air conditioners, which can be used to provide a load-reduction
response within ten minutes.
There are many other projects being undertaken
in this relatively new and exciting area. If you know of others
which deserve a mention here, or can suggest updates, please let
us know by emailing us at: