The decision taken by the Baltic States to exit the BRELL electric ring (Belarus, Russia, Estonia, Latvia, Lithuania) and synchronize with the energy systems of Central Europe created a number of problems, the solution of which requires certain material costs. This is primarily due to the fact that the EU's energy policy sets as its main goal the closure of all energy sources powered by organic fuels and the spread of renewable energy sources (RES). An increase in the number of renewable energy sources is planned to eliminate the shortage of power generation in the Baltic energy systems when electric connections with BRELL are severed. The increase in the number of renewable energy sources with their unpredictable generation does not contribute to improving the reliability of power systems. The article discusses the implemented and planned infrastructure measures in the Baltic energy systems to expand the possibilities of generating and transferring power through transmission lines. To assess the sustainable operation of the Baltic energy systems with a significant amount of installed renewable energy capacity and synchronous operation with European energy systems, a calculation model based on the use of officially available data and their forecast for the future has been developed. Experimental calculations of the possible modes of the Baltic energy systems after synchronization with the energy systems of Central Europe allow us to draw appropriate conclusions regarding the possibilities of improving the reliability and stability of the Baltic energy systems.