Elering launches Estonia's first synchronous condenser

On Friday, Elering, the Estonian system operator, launched the synchronous compensator, which is needed to disconnect the electricity grid from the Russian network and connect it to the continental European grid. It is the first of three synchronous condensers (SynCons) that will be built in Estonia.

"On Thursday, May 11, Siemens Energy delivered Estonia's first synchronous condenser to Elering and today we activated it for the first time. From now on we are useing it in accordance with the needs of the Estonian and Baltic electricity systems," Arno Raadom, project manager for Elering's SynCons, said.

He explained that this is the first synchronous compensator to be built in both Estonia and the Baltic States with a total of three in each Baltic State.

"Once the Baltic States are synchronized with the electricity system of continental Europe, these stations will play a crucial role in ensuring the stability of the electricity system," Raadom explained. Estonia, Latvia and Lithuania have agreed with the European Commission to coordinate their infrastructure with continental Europe by the end of 2025.

The second synchronous compensator to be constructed in Estonia will be located in Kiisa, Raadom said. "The structure is finished and the main equipment has been delivered. The construction of the Viru synchronous compensator has also begun.

Viru SynCon will be constructed near Narva at the Estonian Power Plant.

According to Elering, the synchronous compensators will be put into service as soon as they are ready. They will continue to provide inertia to the system, as well as assist with short-circuit prevention and voltage regulation. The devices are covered by a three-year warranty.

Raadom said that such a device had never existed in Estonia, because we have historically been a part of the Russian power grid, which means that the frequency of the entire system is managed centrally from Russia. "By the end of 2025, we will be fully equipped to synchronize with the continental European electricity grid," he said.

Each country or region must be capable of balancing its own power system in order to participate in the continental European electricity grid. The entire European system operates as a single system, with diverse regions aiding one another as needed.

The synchronous compensator provides inertia to the electrical system. The inertia helps to slow down the rate of frequency change. SynCon provides a few moments of extra time so that if, for example, a power station in the system suddenly stops working and the frequency starts to drop, the inertia provided by SynCon slows the frequency drop, which in turn provides time to start or add back-up power. Thus, the SynCON is the first and fastest "firewall" for maintaining frequency in advance of the start-up of standby power plants at different speeds.

"SynCon is like a spinning top; once the movement starts, it continues to spin for a long time due to inertia," Raadom said.

The operation of the synchronous compensator, or inertia, is also critical in a system with a significant proportion of renewable energy sources, because solar parks, for example, do not produce inertia. Wind and solar farms are unable to control frequency. Inertia is produced by 'old school' rotating apparatus such as thermal power plants and nuclear power plants with their massive and ponderous revolving generators. As the number of these power plants decreases, special equipment to generate or enhance inertia will be necessary.

Three-quarters of the construction cost of the three synchronous compensators to be built in Estonia will be covered by grants from the Connecting Europe Facility (CEF), totaling about €60 million.

The rotor of the synchronous compensator rotates at 50 revolutions per second (rpm), which corresponds to the 50 hertz (Hz) frequency of the alternating current used in Europe.

People involved with the construction of Püssi SynCon, including representatives of the major contractor Siemens Energy from Germany and representatives of subcontractors, as well as energy ministers from the three Baltic states, attended the opening.

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Editor: Mait Ots, Kristina Kersa