The European regulatory environment for electricity market integration envisages strong cooperation and sharing of balancing services between Transmission System Operators (TSOs) on dedicated trading platforms in a competitive market regime. The implementation of such platforms requires a process of standardization of FCR, FRR-A, FRR-M and RR ancillary services. Given the diversity of characteristics of the services procured by TSOs in the Continental European system, it is first necessary to harmonize them.

In particular, regarding FRR-A, two activation schemes coexist, pro-rata and merit-order. The latter is considered to be the scheme that is best suited in market integration and is the one envisaged by Regulation (EU) 2017/2195 on electricity balancing; however, this approach could lead to critical issues for the control and stability of operation of the electricity system.

This report provides a summary of the investigation of the main critical issues of the two FRR-A activation schemes carried out by ELIA (Belgian TSO) and TENNET (Dutch TSO). The report aims at a preliminary assessment of the integration of the two control areas for the exchange of FRR-A, a service currently operated by the two TSOs under pro rata (ELIA) and merit order (TENNET) procedures. Subsequently, the pro rata scheme of FRR-A activation by the national transmission system operator Terna is also briefly described.

The analysis of the ELIA and TENNET study has highlighted at least three options for possible integration of the FRR-A service, including making use of a Full Activation Time (FAT) harmonization process.