To free the Baltic grid, old technology is new again

The Baltic countries – Lithuania, Latvia and Estonia – recently accelerated a plan to cut the electrical chains that keep them tied to Russia. A technical lynchpin to their planned escape from the Moscow-controlled synchronous AC zone is a constellation of synchronous capacitors: free-spinning and fuel-free electrical generators whose sole purpose is to stabilize and protect the power grid.

The Baltic states, all of which are members of the EU and NATO, began to free themselves from Russia’s electrical embrace nearly a decade ago with the construction of high-voltage direct current (HVDC) links to Finland, Sweden and Poland. These alternative sources of electrical support ended the Baltics’ dependence on imported electricity from Russia and Belarus.

Now stabilization equipment is preparing the grid to physically separate from the giant grid to the east and instead synchronize with the continental European grid to the south. In 2019, funding from the EU initiated the necessary grid-enhancing upgrades, and synchronization with Europe was planned for the end of 2025.

“Being on the Russian electricity grid is a risk for Estonian consumers.”

Cost increases have delayed a crucial second link with Poland, and thus Europe, to 2028, but the full-scale invasion of Ukraine and Russia’s air strikes on the Ukrainian network increased pressure on the Baltics to break away sooner. In August, the Baltic states agreed on a plan to switch networks by February 2025 at the latest.

As Estonian Prime Minister Kaja Kallas explained: “Russia’s aggression in Ukraine and its use of energy as a weapon prove that it is a dangerous and unpredictable country, and therefore it is a risk for Estonian consumers to be on the Russian electricity grid.” She said the prime ministers agreed to “leave the Russian network as soon as the technical capability is in place.”

This is where synchronous capacitors come into play. Synchronous capacitors (also called synchronous compensators) are essentially generators that, in normal operation, are spun by an AC mains current and synchronized to its frequency (rather than powered by their own fuel). When power plants and/or transmission lines shut down unexpectedly, the momentum of their rotating mass provides an immediate supply of energy that cushions the blow, thereby protecting equipment and preventing outages.

The first of three synchronous capacitors for Estonia, installed early this year south of the capital Tallinn, provides grid support that will be crucial when the Baltic states disconnect from Russia.European Commission

“It’s like an airbag for the power grid,” says Ana Joswig, Portfolio Lifecycle Manager for synchronous capacitors for market leader Siemens Energy, supplier of the nine synchronous capacitors planned to be operational in the Baltics by the end of next year.

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Joswig says the spinners provide three crucial grid-stabilizing services:

  • Frequency regulation: When the mains power drops or surges, the device immediately releases or absorbs energy to minimize fluctuations in the AC frequency;
  • Short Circuit Current: When the grid experiences a short circuit, the crash voltage releases a triple or more of current from rotating machinery, signaling circuit breakers on the grid to activate and rapidly isolate the fault; and
  • Voltage support: Producing current and voltage that are out of phase generates so-called reactive current that pushes the voltage of the local grid up or down to stabilize the system voltage and/or increase the flow of real current.

Synchronous converters were first deployed in the early 20th century, but hey were rarely used because grid stabilization could be provided by power plants with large rotating generators. But plants with steam and turbine-driven generators are increasingly being replaced by solar panels, wind turbines and batteries that supply their energy via electronic converters. Hence a worldwide comeback for a technology that was invented over a century ago.

In recent decades, the AC network has experienced several events where synchronization breaks down.

Joswig says there has been an additional growth spurt as the energy transition accelerated over the past several years: “Before, some grid operators told me there is no market for the synchronous capacitor. Now they can’t get enough.”

Synchronization with Europe increases the need for network services in the Baltics. Europe has very large power plants, the failure of which can cause greater disruption than the Baltics have traditionally faced. And, Joswig notes, in recent decades the AC grid is experiencing several events where synchronization breaks down, leaving some regions electrically isolated – a scenario that will be extra relevant for the Baltics, while operating with only one AC connection to it continental Europe.

When Spectrum profiled the re-emergence of synchronous condensers in 2015, there was a notable trend towards the conversion of steam generators as coal-fired and nuclear power plants shut down. Today’s notable technological trend, says Joswig, is the addition of flywheels weighing hundreds of tons to increase momentum. All nine of Baltic’s synchronous condensers will have power-amplifying flywheels, she explains, equipping each installation with up to 2,200 megajoules of energy. This roughly corresponds to the kinetic energy of a 3,000-tonne train traveling at 100 kilometers per hour.

As shown, the Harmony Link HVDC cable will give the Baltics another transmission link to Europe. But it will not be completed until 2028, three years later than planned.Elering

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In addition to synchronous capacitors and international connections, the Baltics are further strengthening their electrical systems by upgrading control systems and adding and rebuilding transmission lines. A circuit between Estonia and Latvia, to be ready by the end of 2024, concluded the agreement to speed up synchronization with Europe.

Justinas Juozaitis, who heads the World Politics Research Group at Lithuania’s Military Academy, says Russian action forced the acceleration. First, he says, Russia prepared more quickly for Baltic separation.

Russia and Belarus built new lines to strengthen their own networks. And Russia built four gas-fired power plants and an LNG import terminal in Kaliningrad, a Russian exclave on the Baltic Sea sandwiched between Poland and Lithuania. “By 2021, they had built the infrastructure and proved that Kaliningrad can function independently,” says Juozaitis. That, he says, enabled Russia to disrupt the Baltic power without the risk of blacking out its own territory.

In mid-2022, the Baltics forged a protocol for “emergency synchronization” by which they can switch to Europe’s grid in a matter of hours if needed. The emergency plan calls for the activation of transformers at the Polish-Lithuanian border, the conversion of the country’s HVDC connection to an AC connection and the provision of additional frequency regulation via facilities in Sweden and Finland.

Juozaitis says the fact that European grid operators sped up and completed Ukraine’s synchronization within a month of Russia’s invasion gives confidence that the Baltics can pull an emergency switch. And he says recent events underscore the importance of being ready: mechanical damage caused by a natural gas pipeline from Finland to Estonia and by telecommunications cables connecting Estonia to Sweden. They seem to have been hit around the same time in early October.

Finnish authorities investigating the pipeline damage say their main suspect is a Chinese-flagged container ship, the New Polar Bear; Estonian authorities have said they are tracking the Sevmorput, a nuclear-powered Russian cargo ship that was also near the pipeline and cables when they sustained damage.

“The Russian Federation has the motive and the chronology is very, very strange,” notes Juozaitis. Russia and China have denied sabotaging the equipment.

Juozaitis says NATO has already stepped up naval patrols and other surveillance in the Baltic Sea to protect infrastructure. But he says that the Baltics must also practice deterrence. As he puts it: “They have to signal that if the Russians continue to tamper with submerged infrastructure, there will be consequences.”

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