Lithuania plans to connect and synchronize with continental Europe in 2025, with that connection additional requirements and services will be added to the transmission system services. For frequency control, Ignitis gamyba currently owned hydropower units do not have uniform power-curve characteristics.
Using a grid-scale storage solution, the storage system would allow providing a high-quality frequency containment reserve (FCR) services, compensating for the asymmetries in hydro-unit operations. As for today, the service in the Baltics is mainly provided by the Russian power plants, operating in the post-soviet BRELL energy ring. Virtual coupling of hydro units and battery storage unit can make sure that needed requirements can be fulfilled. For that reason, there is a plan to test virtual coupling of Kaunas hydropower with Litgrid owned 1MW / 1MWh battery storage system.
1MW energy storage system was already installed and tested by Litgrid in one of their switchyards in Vilnius. The plan to test synergy between the hydropower plant in Kaunas and the storage system in Vilnius to meet the requirements for the response to frequency change was established in 2022 Q1. Testing of coupling Kaunas hydropower unit with Litgrid 1MW / 1MWh battery storage system was done in 2022 June.
Test results showed that a battery energy system with correct parameters can compensate for asymmetries in the power curve of a hydropower unit and therefore coupling such two physically distant units can provide frequency containment reserve services. The further optimum size of the battery storage system should be evaluated and a control concept should be prepared and agreed together with the TSO.