High Level Use Cases

The different intended use cases of the demand side response system will have some impact on its design. These use cases reflect the business models of the likely route to market for such a system in the UK.

OpenADR already accommodates all of the following use cases so it is largely a question of how the wider PowerShaper system will do so.

1. Behind the meter optimisation

In this scenario a half-hourly tariff schedule is produced daily by the customer’s electricity retailer and obtained by the aggregator. This doesn’t require any relationship with the retailer, only that this data is available in some way.

An example of such a tariff is the Agile tariff from UK supplier Octopus Energy. This provides a dynamic time of use tariff following the wholesale market spot price. Tariff schedules are published by Octopus daily and can be accessed by an API.

However it is obtained, the tariff data is then used to generate an OpenADR demand response event for each user and their assets which is sent to the HEMS for control. The HEMS then attempts to operate the assets in a cost-optimal manner. In the case of an EV, for example, this may result in deferring charging at peak times to cheaper times over night.

The relevant OpenADR ‘program’ (use case) is ‘Critical Peak Pricing’ or ‘Residential EV TOU’ depending on the technical characteristics of the loads (as described in the OpenADR 2.0 Demand Response Program Implementation Guide ).

2. Flexibility Market

In this use case, the aggregator receives requests for activation of flexibility assets under its control from other Market Actors (suppliers/DSO/SO). These requests may or may not be formatted according to the OpenADR specification (indeed they could be compliant with another standard, such as USEF, or a proprietary one). The aggregator estimates how best to utilise its portfolio of assets to maximise income generated and then activates assets accordingly by sending OpenADR events to the HEMS for direct control.

No flexibility markets of this kind currently operate in the UK although a USEF market with these characteristics will be trialled in the FUSION project. The relevant OpenADR ‘program’ (use case) is ‘Capacity Bidding Programs’ or ‘Fast DR Dispatch’ may be relevant depending on the operation of the flexibility market.

3. DSR Direct Load Control

In this use case there is a pre-existing agreement between the aggregator and the DSO for the provision of flexibility. This flexibility comes from a portfolio of domestic assets, which are activated (or deactivated) in response to a predetermined signal.

We envision this signal being transmitted over the internet. For example, in the recent expression of interest by Western Power Distribution, they describe a REST API which the DRMS must implement in order to exchange information with the DSO.

Ideally DSOs would implement an OpenADR interface but this is not required. On receipt of the signal from the DSO the system identifies the appropriate assets (for example, those located in a specific geographical area) and initiates a demand side response event. This is done according to the control flow described by OpenADR, including the ability of asset owners to override the event (subject to some penalty or non-compensation).

4. Conclusion

In each case, once the event is over a report is generated containing information such as the number of participants, the proportion of assets responding (to all control signals), the estimated flexibility delivered (in kW/kWh). This is combined with data obtained from the smart metering system, such as the difference between measured load and historical average load in order to provide an estimate of the demand side response effect for reporting and auditing.

It is envisaged that in the case where multiple use cases were being pursued one would take priority over another and determine which event is communicated. In the case of (1) and (2), this can be determined by whichever is cost optimal. Use case (3) would likely take priority irregardless due to likely contractual penalties from not participating in an event.

This use cases can accommodate more traditional active network management scenarios and flexible connections as well as supporting more recent local flexibility tenders from e.g. UKPN and ENW. By supporting both forms of direct control as well as more dynamic market-based approaches to procuring flexibility, OpenADR can help DNOs transition to future paradigms for DER control.

The ‘Capacity Bidding’, ‘Thermostat Program’, or ‘Fast DR Dispatch’ may be relevant OpenADR programs depending on how the DSO scheme operates.