Relationship between regulated and deregulated players

An issue already mentioned above is about who informs the DSO and the TSO of the AD actions for the purpose of the technical verification. Either the seller of the service (aggregator) or the buyer of the service might do so (in an aggregated way at distribution network level).

It seems reasonable that the aggregator informs the system operators. Indeed, the information for the technical validation must include locational data of the consumers involved and the aggregator is the player who knows how to link that locational data with the AD actions that it is planning to carry out (see Section 2.2.3).

Different types of relationships and information exchanges are needed between aggregators and DSOs/TSOs in order to manage the following issues:

- Purchase of AD products by DSO/TSO from aggregators

- Technical validation of AD actions.

- Management of energy payback effect: DSOs and TSOs will have to ensure the energy payback effect does not cause any problems in the distribution or transmission networks.

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- Consumer and aggregator response monitoring.

These relationships are particularly important because the DSO/TSO must ensure the operation of the network in a secure and efficient way. Furthermore they are part of the ADDRESS Technical and Commercial Architecture.

2.4.2.1 Commercial relationship

Pure commercial relationships deal with the purchase of AD products by the TSO or DSO from an aggregator. The commercial relationship between TSOs/DSOs and aggregators is defined by the characteristics of the products that the aggregator can offer to the TSO/DSO in order to fulfil some of its needs. Examples of such products/services have been given in Section 2.3.2. They are described in detail in Appendix D according to the template presented in Section 2.2.2.

2.4.2.2 Technical validation by System Operators

The actions performed by aggregators through the management of their consumers’ portfolio have an impact on the power flows and voltages on the lines and other network equipment. There might be some cases where network constraint violations will occur. In order to avoid these network constraint violations, DSOs and TSOs should assess the impact of prospective AD actions and take appropriate measures when these actions cause or could cause a problem.

This is a situation similar to the one that nowadays TSOs face in the transmission networks. Currently, TSOs verify at certain times that the power transactions agreed in the electricity markets (open markets, bilateral contracts, etc.) comply with the network constraints and otherwise facilitate the way to avoid such constraint violations. In this respect, AD could play a role similar to generation and large industrial consumption in the transmission network. But the verification of the impact of active demand in distributions network is a new issue then to be addressed.

Discussion on the need for technical validation of AD actions

According to the current regulation, at the initial steps of active demand deployment it will probably not be necessary to perform any technical verification because AD will not have an appreciable impact in the DSO’s and TSO’s networks. The network operators will ensure that their networks will be able to host any active resource connected to them, or they will put limits on those resources when and where they do not ensure secure operation.

However, as more active resources become connected to the network and in a future with high deployment of active demand solutions, it is reasonable to think that the limits set by TSOs/DSOs will have to be removed and the impact of AD on the grid will increase. In this case, verification of active demand actions will likely be needed.

Additionally, in the active grids of the future, load control together with generation set-point control will probably be part of integrated voltage control systems, along with conventional voltage control systems, and of other active grid management systems. So, both load reduction and load increase could be of some importance for the DSO and thus will need to be validated.

However it is clear that certain types of AD actions (e.g. involving volume lower than specified thresholds) might not need to be validated by both the DSO and the TSO.

It can be concluded that depending on country specific regulations, electricity sector characteristics, degree of AD penetration, amount of AD power being traded and the specific AD service

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characteristics, the technical validation processes could be simplified or removed. This topic will be further discussed and studied in WP3 of the ADDRESS project which deals with developments for the DSO and TSO and the grid operation.

In this document the most general case is considered, where technical validation processes are performed by DSOs and TSOs. Even if as discussed above it could happen that for certain AD actions and at the beginning of AD deployment these technical validation processes might not be needed. In any case, secure operation of networks is crucial and must be guaranteed, but at the same time it must be ensured that the technical validation does not raise any unnecessary barriers against AD development.

Technical validation of AD actions

This technical verification process will mainly consist in performing load flow calculations in the network taking into account the consumption increase or decrease communicated by the aggregator and associated to certain network identifiers, load areas or geographical areas. After executing the calculation processes the DSO/TSO will verify that all the network constraints are not violated, that is, power flows and voltage profiles in lines and nodes are in between admissible limits. If this is the case, the DSO/TSO will see how to remedy to the problem with solutions at its disposal. If it cannot find any such solution, the DSO/TSO will determine a curtailment factor for the AD products (e.g. limit on the MW amount) such that no constraint is violated with the curtailed product otherwise is not possible it will reject it completely.

For the purpose of the verification, each DSO has to know how much power would be injected in the nodes of its network by each AD action proposal.

The TSO has to know how much power would be injected at the boundary nodes with each distribution network by all the AD actions involving that network.

If no constraint is violated, the AD actions are accepted and acceptance signals are sent to the aggregators.

What happens in the case of technical invalidation by system operators?

As mentioned above, if the proposed AD action does not comply with network constraints, the DSO/TSO should determine how to remedy to the problem with the solutions at its disposal. If it cannot find any such solution, the DSO/TSO determines a curtailment factor for the AD product (e.g. limit on the MW amount) with the objective of curtailing the least possible amount.

Additionally, the DSO/TSO computes and publishes a sensitivity matrix expressing the constraints on the distribution/transmission networks as guidance to the interested parties:

- for possibly arranging additional flexibility exchanges (such as AD products), for instance in a second market round or,

- for preparing future offers and submitting them to the market.

Sensitivity matrices for network constraints will be public. With these DSO and TSO sensitivity matrices, all parties should be able to know how incremental flexibility exchanges could be arranged to comply with the network constraints. Therefore it is expected that the aggregators will be able to build their offers and AD products in a better way to reduce as much as possible the rate of rejection or volume of curtailment of its AD products.

For services provided to deregulated players, the TSO sends to each DSO the transmission curtailment factors for the AD products pertaining to a DSO’s distribution network and in turn the

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corresponding DSOs send to the aggregators curtailment factors taking into account both the constraints on the distribution and transmission networks.

For services provided to regulated players, the results of the technical verification (curtailment factors) will be sent to the aggregators by the buyer of the AD product (respectively the DSO or the TSO depending on the case) taking into account the results it has received from the “other” regulated player involved (respectively the TSO or the DSO depending on the case).