Individual electricity consumers (e.g., households or SMEs) can often time-shift their electricity consumption or switch electricity consumption profiles for some of their local devices (e.g., heat-pumps, electric vehicles, and dish-washers):
A so-called Flex-offer offers a standardized and unified way of describing flexibility from a wide range of such flexible devices (resources). Irrespective of the device type, electrical energy amounts and associated flexibilities can be explicitly captured using a flex-offer. For example, energy amounts and associated flexibilities in time and energy amount for charging the battery of a single electric vehicle between 10pm and 8am can be represented by a single flex-offer, shown below in its basic form:
In the above figure, there is a baseline profile (thin red lines) which represents the device operation starting at 3 am when no flexibility is activated. With respect to this baseline, it is possible to advance or delay the device operation within the allowed time flexibility interval. Further, it is possible to increase or decrease electricity consumption within the allowed energy amount flexibility ranges (orange intervals) at every 15min time interval within the full device operation duration of 2 hours.
Similarly, flex-offers with negative energy amounts can be generated for flexible resources producing instead of consuming electricity.
Thousands (or millions) of such flex-offers, both for consumption and production loads, can be efficiently aggregated into macro flex-offers representing much larger energy amounts suitable for energy market trading. Then, aggregated flex-offers can be scheduled (optimized) and finally disaggregated back again with no or little loss of flexibility:
Flex-offer life cycle
Each individual flex-offer undergoes the following life-cycle:
- First, a flex-offer is created for a specific flexible resource, e.g., based on (1) the model of the flexible resource, (2) user settings, (3) current state, and (4) external data.
- Second, a flex-offer is aggregated together with other (similar) flex-offers, forming an aggregated flex-offer with larger energy amounts and flexibility.
- Third, the aggregated flex-offer is scheduled by including it into an optimization. During scheduling, all aggregated flex-offer flexibilities are fixed, i.e., the operation start time and individual energy amounts are instantiated such that actor-specific (an aggregator or a balance responsible party) objectives and constraints are met.
- Fourth, the energy profile of the aggregated flex-offer is disaggregated, i.e., an energy profile is assigned to the original flex-offer (as well as other non-aggregated flex-offers) such that all constraints are respected and energy balance is ensured.
- Five, the execution of the assigned flex-offer energy profile is tracked, ensuring that the assigned flex-offer schedule is met.
- Lastly, the flex-offer execution is settled, i.e., the issuer of the flex-offer (e.g., a household) is rewarded based on its offered flexibility and flex-offer execution performance.
Flex-offer ICT infrastructure
A large-scale “Big energy data” ICT infrastructure is used to manage flex-offers: collect, aggregate, schedule (optimize), disaggregate, execute, and settle flex-offers.
It interconnects the actors of the Harmonized Electricity Market Role Model, such as electricity prosumers, aggregators, traders (balance responsible parties), and system operators.