The flow-based coupling method
Flow-based coupling within the CWE region went live on 21 May 2015.
Prior to that, these four bidding zones were coupled on a Net Transfer Capacities (NTC) basis, meaning that limitations on exchanges were set bilaterally for each border (one constraint per border and per direction, implicitly taking into account the state of the network).
Constraints now explicitly take into account the physical network infrastructure in the five countries. Cross-border exchanges are thus optimised to reflect the actual physical capacities of networks as accurately as possible. This requires very close coordination between transmission system operators in CWE countries.
In sum, it is no longer possible to consider borders separately, and indicators previously used for the France-Belgium and France-Germany borders have been replaced by France-CWE region indicators