The energy transition involves the evolution of the electricity system towards widespread generation from renewable energy sources and simultaneous decarbonization. This results in a decrease in system inertia and resources for frequency regulation. Therefore, assessments are needed of the adequacy of flexibility resources aimed at frequency regulation.

The deliverable presents two activities. The first concerns the extension of the Innovative Services: Automatic Tuning (SeTA) procedure for calculating the minimum numbers of fast innovative grid frequency adjustments that may be needed in scenarios of very high renewable penetration, in order to enable analysis over 8,760 hours per year, instead of a single hour as in the previous version. This development, which also involved some methodological advances, provides useful indicators for planning new resources for fast primary frequency regulation and synthetic inertia. Application to a scenario in the Sardinian system at 2030 shows that, under particularly critical conditions and under conservative assumptions, rapid adjustments are essential in order to avoid load shedding in case of generation loss (under-frequency transients) or limit the reduction of power generated by renewable sources in case of load shedding (over-frequency transients).

The second activity concerns the definition of specifications for the refinement—in the Grid Flexibility (GRIDFLEX) procedure for assessing flexibility resource adequacy in the Italian grid—of the calculation of mutual relief between market zones for the purpose of more accurate assessments of the margins available for traditional primary, secondary and tertiary frequency adjustments, also taking into account the contribution of market zones not bordering the zone under consideration, but interconnected through intermediate zones. The specifications cover the possible implementation of an approximate heuristic approach, for which short computational times are expected, or a rigorous, but more computationally time-consuming approach based on linear optimization.

The next annual report will define specifications for extending the calculation of fast service quantities to multi-zone models. In addition, the calculation of mutual aid between zones for conventional regulation will be implemented.