Management of the energy payback effect

As described in Section 2.2, at the end of the control action (carried out to provide demand flexibility) a energy payback effect may occur. Depending on the pieces of equipment used in the provision of

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demand flexibility, this effect may appear directly after the end of the action or later, for instance it may occur several hours later. Depending of its size and shape (amount of power and energy involved), the energy payback effect may have adverse consequences on the electricity system and the affected players. For instance, it may cause:

- load and power flow increases on the networks with a risk of overload and congestion. The affected players are the DSOs and even the TSOs in severe cases.

- Imbalances between generation and consumption with economic consequences (penalties,etc) and technical consequences (frequency drop or increase, possible impacts on system stability, use of the power reserves, start up of generating units, ...). The affected players are:

o from the economic point of view: the BRPs, retailers, … and TSOs, depending on the market structure and the regulatory framework,

o from the technical point of view: the TSOs, the producers, … and maybe even all the players in extreme (and hopefully almost improbable) cases of blackouts;

- depending on the case increase of energy consumption of the consumers and increase of their energy bills. The affected players are: the consumers (and the retailers).

- impacts on market prices (unexpected increase or decrease). The affected players are the participants on the affected markets.

It is thus important to limit or manage this effect and for instance avoid the possible power demand increase at consumers’ premises as soon as the action ends. To this purpose different possibilities may be considered. In particular control actions may be carried out at three levels:

- at the level of the Energy Box through the control of the appliances and possibly present embedded DG and storage at the consumers’ premises,

- at the level of the aggregators through signals sent to the consumers who have participated in the delivery of the AD products,

- at the level of the other electricity system players.

The Energy Box should have the knowledge of the pieces of equipment which participated in the AD flexibility provision and probably also of the status of the other appliances and DER in the house. Therefore specific strategies could be implemented in the Energy Box to limit the energy payback effect at the level of the house and to carry out control actions on the controllable equipment taking into account this information, the signals sent by the aggregators, and its own internal technical and economic optimisation criteria. Note that the action of the Energy Box to limit the payback is limited to the local level (level of the house or the building).

The aggregator will act at a more aggregated level, namely at the level of its portfolio of consumers. Indeed the action of the aggregator to mitigate the payback effect:

- will most probably concern the consumers who participated in the AD provision,

- may also concern other consumers in the portfolio depending on the knowledge that the aggregator has on these consumers, for instance on the location of the consumers on the networks and type of controllable equipment they have.

The aggregator will act through the price and volume signals it sends to the consumers. Different possibilities will have to be combined:

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decrease, send a signal to consumers to increase the consumption in a given time period before the planned delivery (load reduction);

- limitation of the payback effect directly after the end of the delivery by sending a signal to consumers to counteract the possible load increase or decrease to a certain extent and at least to meet the requirements that may be specified by the buyer of the AD product in the request (see the templates of Figure 6 and Table 8).

- Control of the payback effect on a longer term by sending signals to consumers to “smooth” or distribute the energy consumption recovery on a longer period of time in order to avoid significant load increase or decrease at unexpected times maybe hours after the products delivery.

All these actions require a good knowledge of the consumers both in terms of their consumption behaviour, of the characteristics of their equipment and of the strategies that may be implemented in the Energy Box (in particular if these strategies deal locally with the management of the energy payback effect).

The strategies to manage the payback effect both at the level of the Energy Box and of the aggregator will be studied in detail in WP2 which deals with the Energy Box and the aggregator (see Appendix B).

The others players have the possibility to specify requirements on the limitation of the energy payback effect in their AD product requests when they are the buyers of those products. This has already been discussed in the previous section (see the templates of Figure 6 and Table 8 in Section 2.2.2).

Clauses may also be specified in the contract negotiated between the buyer and the aggregator. At a higher level, minimum requirements may be defined by the regulation or the market rules. It will then be the responsibility of the aggregators and other players to comply with these rules.

The management of energy payback effect in the regulation, the market mechanism and the contractual structures will be studied in detail in WP5 (see Appendix B).

Regarding regulated players (DSOs and TSOs), another more specific measure will be studied (in other WPs). It can be envisaged that for the technical validation of the AD product delivery, the aggregator may provide the DSO information on the expected energy payback effect that may occur (after mitigation) due to the AD actions it will perform. The DSO and TSO can then verify if the payback causes any problem and inform consequently the aggregator. In their answer to the aggregator, the DSO and TSO may also specify the limits on the payback effect that may not be exceeded. The aggregator will then be in charge to minimize its payback to meet the requirements. In a similar way to the delivery of the AD service itself, the energy payback effect will probably have to be assessed and/or measured. In this case, the reference (base load or base demand) used for such an assessment should be clearly defined. As for the AD product itself, different possibilities may exist (see Section 3.2.3 below).