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Current work on demand control


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". The GridWise Alliance has also been established, a US-based group which promotes technologies to help intelligent demand management of electricty.

Econnect 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 stability.

RLTech, 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 appliances.

Martin Energy Limited promotes the concept of "flexitricity", 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:




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set up by a grant from the Esmée Fairbairn Foundation and supported by charitable donations.