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By agreement between the transmission system operators of the Baltic states – Elering, AST and Litgrid – a test of the isolation of the countries’ electricity system from the Russian power system and island operation will be held on 8 June 2019 or as an alternative, 29 June 2019.

“To achieve capability for stable longer-term functioning of the Baltic states’ electricity systems as a separate frequency areas by 2025 and to be prepared to synchronize with the continental Europe frequency area, the Baltic states will have to test various aspects of the independent functioning of the electricity system several more times,” said the chairman of the Elering management board, Taavi Veskimägi.

In the course of the isolation test to be held in June, the electricity systems of the Baltics will be disconnected from the Russian frequency area for 12 hours. During that time, the systems will remain connected by DC connections to the Nordics and Poland.

To isolate the Baltic electricity systems from the Russian grid, all nine power lines connecting the Baltics to Russia’s main territory and Belarus will be disconnected one by one. Unlike earlier similar tests, this time the power lines between Lithuania and Russia’s Kaliningrad oblast will be switched off and similarly to the Baltic states, the Kaliningrad power system will also function as a separate frequency area during the test. At the end of the test, the lines will be switched back on.

During the test, the focus will be on testing the efficient management of processes on the power grid’s frequency. A number of constituent tests will be held in the context of the isolation test. Among other things, the impact of a shutdown of a large generation unit on the frequency will be simulated.

During the test, the capacity of the direct current connections between the Baltics and Nordics will have to be limited to reduce the risk arising from a possible malfunction in the largest element of the power system. To increase the flexibility of the electricity system, more generation capacities than normal will be launched in the Baltics in order to conduct the test. Generation equipment must also maintain larger-than-normal reserve capacity to be prepared to efficiently and automatically increase or decrease generation in response to changes in the frequency in the electricity system.

The Estonian electricity system has been previously isolated from neighbouring systems as a test in November 2006 and April 2009. The most recent isolation test in which the three Baltic electricity systems and Kaliningrad were isolated from the Russian system, took place in April 2002.