Benefits of Sharing and Exchange for the Procurement of aFRR by Transmission System Operators Using a Chance-Constrained Approach

To ensure a continuous balance between generation and consumption, Transmission System Operators (TSOs) procure different reserves in advance and activate them in real-time when necessary. Procurement processes are still unharmonized in Europe. However, European legislation calls for their evolution and the implementation of reserve Sharing and Exchange between TSOs. We propose to extend a chance-constraint sharing method from the literature into a Joint sharing and exchange algorithm by introducing reserves price curves. We also add new constraints to reflect the need for locally procured capacity in some operational context. The methodology is applied to five countries of Western Europe, focusing on automatic Frequency Restoration Reserve (aFRR), highlighting 1) the respective benefits of Sharing, Exchange and Joint sharing and exchange, 2) the sensitivity to cross-border capacity allocation, and 3) the impacts of additional local procurement criteria.