Demand-Side Management

In a national grid network `Demand-Side' refers to the user's local system, as it is their demand for power that the grid aims to satisfy. Typically the grid suppliers anticipate the required energy output, by predictions based on previous years and expectations of particular peaks (such as the end of the nation’s favourite soap). Demand-Side Management, therefore, is the idea that the power generation and supply can be managed at the user level.

The need for demand-side management is increasing, because of the rising aggregate capacity of renewable generators such as wind turbines and photovoltaic panels that are embedded in electricity distribution networks. These are seen by networks as a negative load whose presence depends on the weather. This intermittent negative load will increase the variability of demand and hence drive up distribution costs unless active management of demand can mitigate the effect.

An established, but limited, technique for demand side management in the UK is the radio teleswitch system. This controls the switching times of electrically heated thermal storage radiators, using a digital signal carried within the BBC Radio 4 broadcast on 198 kHz. The radiators are switched on for a 7 hour period overnight when other demand is low; the radio control allows the switching times to be varied to assist balancing of supply and demand.

There is now potential to develop this system so that a much wider range of appliances, such as refrigeration equipment, heat pumps, tumble driers, etc. can be included. Particular benefit would be obtained if small and micro Combined Heat and Power (CHP) units could be managed so that their electrical output is available at times of peak demand. However, direct control of such a diverse population of appliances is clearly impractical; instead the broadcast signal should influence the operation of each appliance but allow user needs to take precedence.