On 29 of May, Regional Group Continental Europe of the ENTSO-E, the European Network of Transmission System Operators, announced about the signing of the interconnection agreement and technical terms and conditions of interconnection by the power transmission operators of Poland, three Baltic States and supporting countries, upon implementation of which – Lithuania, Latvia and Estonia will become a part of the European power system.

These are the most important documents in the process of Baltic synchronisation with continental Europe.
‘In a very short time we managed to put the synchronisation project on the rails and the train that will connect the Baltic power systems with the reliable and modern European energy system is gaining speed now. Through joint efforts, determined and responsible work, we reached the irreversible stage of the project and from now on all our efforts must be focused on completion of specific technical works, the list of which is already final,  by 2025’, said Minister of Energy Žygimantas Vaičiūnas.
The Interconnection agreement defines the rights and duties of the parties to ensure compliance of the Lithuanian, Latvian and Estonian power transmission system operators (TSOs) with the established requirements and assumed obligations.
The Agreement will be implemented in accordance with the catalogues of connection conditions. It is a code of 409 technical and practical operational standards and indicators, upon implementation of which, Lithuania, Latvia and Estonia will connect and operate in the same frequency with continental European power system. At present, Lithuanian power system meets approximately 40 per cent (169) measures established in the connection catalogue. The situation in Latvia and Estonia is very similar.
‘We highly appreciate solidarity, professionalism and constructive cooperation of our partners in Europe, Poland, Latvia and Estonia in creation of the energy future of three Baltic States in Europe. We understand the signed document as our commitment to complete the agreed works in timely and cost-effective manner. We are already working in this direction; we have completed many works and are already considered by our partners from ENTSO-E as trustworthy and professional partners, worth this trust’, said Litgrid CEO Daivis Virbickas.
The catalogue of measures defines indicators and measures that are important for operation of the power transmission systems of each Baltic State. They are related to frequency management, activity planning and accountability and reliable operation of the transmission system. Lots of attention is focused on specialists’ training and preparation to work together under new conditions.
It was agreed on modernisation and strengthening of the domestic power transmission systems of all three Baltic States during the first stage of works, which will last until 2021. This stage has already received maximum financing from the European Union.
The goal of the second stage simultaneously implemented is to finalise the stage of strengthening capacity of the power transmission link between Lithuania and Polish LitPol Link, with the system operators proportionally dividing the inertia requirement to build synchronous compensators in the Baltic States and upon coordination with the ENTSO-E to conduct a joint test of the operation in ‘island’ regime.
The goal established in the final stage of works is to complete the Harmony sea link construction and implement the remaining measures stipulated in the catalogue of connection conditions by 2025.
To ensure energy security of their countries, Lithuania, Latvia and Estonia agreed on synchronisation of their power systems with Europe by 2025. Until now, these three countries are operating in a synchronous mode in so-called BRELL ring of the post-soviet power system.
More information on the agreement can be found on the ENTSO-E website.