Lithuania and Poland Tests Emergency Support on Electricity Interconnection

On Dec. 4, Litgrid and PSE, the operators of the Lithuanian and Polish electricity transmission systems, carried out the emergency support test on the Polish-Lithuanian interconnection. The test was aimed at verification of Lithuanian system restoration and black-start capabilities using the interconnection together with newly installed autotransformers in Alytus substation.

The emergency support test simulated a situation where the largest Lithuanian power plants that are shut down and have the possibility to restart after a black start are supplied with electricity from Poland. Lithuanian consumers were supplied with electricity without disruption, so the test was not affecting the consumers.

"This is a historic test not only for energy independence but also for national security. The test shows that we have a tested synchronous connection, and our main electricity generation capacity is ready to work in the continental European system.", said Dainius Kreivys, minister of energy, Lithuania. "This means that in an emergency, we can ensure the uninterrupted operation of the country's electricity system with the help of Polish partners. This is the geopolitical turning point, preparing for the final connection of the Lithuanian electricity system to the networks of continental Europe in 2025.”

“We are glad to work together with our Lithuanian partners and to perform different simulations aimed at the strengthening of the cooperation between our systems. The performance of the test is one of the commitment stemmed from the bilateral cooperation of PSE and Litgrid, initiated in 2019, which has a goal of enabling restoration and black-start capabilities through the line that may be utilized in both directions, i.e. in case of restoration or blackout in one of the system, the support can be provider from the other one,” said Eryk Kłossowski, CEO of PSE.

“This was one of the most technically challenging tests in Lithuania's energy history. This time we had to coordinate not only with our domestic electricity producers, but also with the Polish system control center in Warsaw. This test highlighted the technological readiness of the equipment and demonstrated the level of professionalism of both companies’ energy specialists. We have managed this task in an exemplary manner, but we still have a lot of work to do to modernize and expand Lithuanian power grids and strengthen system management in preparation for autonomous frequency control and synchronous operation together with our partners in continental Europe,” said Rokas Masiulis, Litgrid's CEO.

The test of the emergency assistance was carried out according to a program agreed in advance between the Lithuanian and Polish transmission system operators. The test started from Saturday early morning and lasted about half a day.

During the emergency test, the substations of Alytus, Kruonis Hydro Pumped Storage Plant (HPSP) and Lietuvos elektrinė, two transmission lines Alytus-Kruonis HAE and Kruonis HAE-Lietuvos elektrinė were disconnected from the rest of the Lithuanian power system, Lithuania's largest power generators, the Kruonis HPSP and the Combined-cycle gas turbine (CCGT) at the Elektrėnai complex, as well as one of the new autotransformers installed at the expanded LitPol Link converter station, took part in the test. All these elements operated during the test synchronously with Polish system.

Voltage was then transferred in stages from Poland to the Lithuanian system via the 400 kV Alytus-Elk Bis overhead line. The electricity transferred from Poland was used to start up CCGT and Kruonis HPSP, and then was transferred from Lithuania to Poland. During the test, LitPol Link was not available for trading.

Almost half a hundred employees from Litgrid, PSE and Ignitis Gamyba helped to implement the test program. Following the test, Litgrid and PSE specialists are carrying out data calculations and analyzing the test results, and detailed reports will be produced by the operators in the next few months.

The emergency support test has been performed immediately after the completion of the LitPol Link extension and the installation of new autotransformers in Alytus substation. Several other crucial tests are planned before synchronisation with the CESA. A Lithuanian isolated operation test is planned for 2022, followed by a joint isolated operation test of the Baltic power systems.

Until now, Lithuania, Latvia and Estonia, together with Russia and Belarus, have been operating in an IPS/UPS system where the frequency of electricity is centrally regulated in Russia. Connection to the continental European grid and synchronous operation with Poland, Germany and other continental European countries will be ensured by 2025 at the latest.