Historically, demand response has been designed as load shedding, a response to various problems encountered by power distribution networks: reduction of the peak consumption, reduction of congestions, avoidance of blackout. It consisted of interrupting some loads on command or on schedule at appropriate times.
Although still very present in the minds, this vision dates a little. Not that these actions of shedding have become useless, but energy systems need more interactions with consumers and vice versa.
Indeed, traditional demand response serves the needs of demand-capacity balance at the time step of several hours. There are balancing requirements at much shorter time steps, for example for frequency regulation.
The answer to these needs does not translate into a shedding of several quarters of an hour but rather into a modulation of consumption ie a variation of consumption around a nominal value.
Are there loads capable of meeting such needs?
Let us take the example of air conditioning? The compressors start when the temperature reaches 21 ° C, for example, and stops when it has dropped to 19 ° C. By varying the temperature between 19.5 ° C and 20.5 ° C, a margin of action of at least 0.5 ° C is offered upwards or downwards which can be mobilized at any time to contribute to the balance of an electrical network. And this without changing the comfort of the users.
This approach is global: it is necessary to measure the effect of more frequent start-ups of compressors, which can have consequences on their aging, to take into account the system of regulation of the air conditioning, not always favourable to this type of actions. However, this approach is not theoretical: it reveals an important potential for flexibility.
Such examples are numerous and allow a control of the demand at any moment, during peak periods as in periods of low consumption. If the load shedding is, according to the countries, rather rarely valued at its right level, the modulation offers much more important valorization opportunities, on the adjustment mechanisms, for example.
More than load sheddings, the modulation of consumption places the consumer as an integral part of energy systems. Moreover, it opens the door to a new positioning of the utilities as a global energy flow valuer: a real value to be brought to customers, all the more important as the supplier is global in its positioning.
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