According to of Appendix 1, Article 5.2 of the Regulation (EC) No 714/2009 of the European Parliament and of the Council of 13 July 2009 transmission system operator (TSO) is obliged to publish scheme for the calculation of the inter-connection capacity for the different timeframes, based upon the electrical and physical realties of the network.
Transfer capacities of the interconnections between power systems are determined as follows:
- Total Transfer Capacity (TTC) between transmission networks of different neighbouring countries is determined for the 330 kV transmission network, taking into account criteria, essential for security of power supply;
- Transmission Reliability Margin (TRM) is the power flow deviations statistical analysis of the previous period for a given transmission network. It provides analysis of the power flow deviation, i.e.,the difference between planned and actual power flow of transfer capacities of the interconnection;
- Interconnection Net transfer capacity for the electricity market (NTC) is determined by subtracting Transmission Reliability Margin from Total Transfer Capacity ;
- Already allocated transfer capacity (AAC) is the total power capacity that has been actually assigned for the trade after the results of the electricity market trading session;
- Available transmission capacity for the electricity market (ATC) is a part of the transfer capacity for the electricity market (NTC) which has remained and available in each trading interval after each electricity trading session.
The Total transfer capacity of interconnection calculated in accordance with the methodology approved by the Baltic countriesand countries of the BRELL electric ring (Methodological instructions for stability in the power systems of electric ring of Belarus, Russia, Estonia, Lithuania and Latvia). Interconnection transfer capacity for the trade between the Baltic countries is calculated in accordance with the common rules accepted by Baltic TSO.
From 1st of January 2016 and beyond Cross-Zonal Capacity Calculation, Provision and Allocation within the Baltic States and with the 3rd Countries will be performed according to the Baltic TSOs’ – AS „Augstsprieguma tīkls”, AS Elering and AB Litgrid – commonly developed document “Terms, Conditions and Methodologies on Cross-Zonal Capacity Calculation, Provision and Allocation within the Baltic States and with the 3rd Countries” (further - Rules). Cross-zonal capacities calculated for the year 2016 (for Year, month and week periods) take into account the Rules.
BRELL documents that are mentioned in Rules and have no ristrictions on publication are given here:
Transfer capacity allocation principle that are applicable till 31.12.2015 are given here.