The dawn of virtual transmission – pv magazine International
Excerpt from pv magazine 08/2022
It is the small battery that could. In Vilnius, the capital of the Baltic state of Lithuania, a 1 MW/1 MWh lithium-ion battery has changed the perception of the role of battery energy storage systems in power grids. And with solar and wind penetration growing rapidly in many parts of the world, grid-scale batteries can play a critical role in making optimal use of transmission and distribution networks and enabling renewable energy to cross national borders.
The 1 MW battery in Vilnius is named Litgrid Innovation Platform, conceptualized in November 2019 and completed in December 2021. Of importance in Europe, it is owned and operated by a Transmission Grid Operator (TSO) , the public company Litgrid. And while small for a grid-scale battery, it was driven by larger geopolitical forces and is likely to have an outsized impact on energy storage in the Baltic region and beyond. .
As a hangover from the Cold War period, Lithuania became part of the Russian-Belarusian Synchronous Electricity Zone. The decision was taken in 2018 for the country, in cooperation with the European Union and together with its neighbors Finland, Latvia, Sweden and Poland, to join the Continental European Synchronous Space.
Making this integration a reality is no simple undertaking, and when Litgrid engineers came up with a list of requirements for European integration, it had over 300 items. One of them was the application of battery storage to support the country’s power grid.
“When two synchronous areas connect and operate synchronously, sometimes the synchronous interface may be lost, because it is an overhead line, and there may be a tree falling, lightning may strike, or a bird may strike, and at that moment the synchronous zone could split into two,” says Litgrid Strategy Department Director Liutauras Varanavicius. “At that time, the ‘Free Baltic States’ would operate in an isolated role , this mode is technically and economically a dramatic mode for us – it’s temporary, most likely it could last for hours but it could also take days or weeks. And the system must remain stable, reliable and also efficient and optimized under these circumstances.
The ability of battery energy storage systems to react quickly to grid events has made their application well suited to the needs of Lithuanian grid operators under the European integration project. If a disruption of the interconnection between countries in a synchronous area were to occur, a battery would be able to charge or discharge rapidly, maintaining the frequency on the grid momentarily isolated, ensuring a stable supply of electricity.
There were alternatives to the batteries considered by Litgrid engineers. These include the use of high voltage direct current (HVDC) transmission or the implementation of demand response, whereby electricity consumers are incentivized to reduce their consumption for a period of time. . Varanavicius notes that the latter mechanism is not yet in place in Lithuania, although the concept has been endorsed by regulators, aggregators and lacking market mechanisms. And while HVDC lines have been studied, it has been found that batteries would be more efficient because they allow electricity exchanges between states to continue unaffected.
“My engineers also explained that if we were to do this instead of batteries, we would need to proactively pull capacity from the traded market in advance,” says Varanavicius. “So it’s less efficient because you’d be limiting electricity trading, which is socio-economically beneficial where wholesale prices are lower.”
Litgrid tested 11 functions on the 1MW innovation platform project, with a decisive result: the proof of rapid response capability was verified. Grid operator engineers found that the battery could go from -1 MW to +1 MW in just 1.57 seconds. “That’s exactly why we were interested in batteries from the start.”
200MW stage 2
Given this successful proof of concept, four 50 MW grid-scale battery projects are being installed on the Lithuanian power grid by Energy Cells which, together with Litgrid, is part of the EPSO-G Group. The batteries are currently installed at four substations in Vilnius, Alytus, Utena and Šiauliai, with completion scheduled for the end of 2022.
The batteries making up the 200MW multi-site project are somewhat limited, as they will only provide a “fast and flexible emergency power reserve”. Under EU regulations, TSOs are not allowed to own battery assets that participate in energy markets through frequency regulation markets or energy arbitrage – which is applies in this case due to the ownership of Energy Cells.
Regulatory limitation of TSO-owned batteries in the EU appears likely to foster the emergence of a new business model, in which TSOs will contract with third parties who own grid-scale battery assets for the provision of synthetic inertia, frequency regulation or other services. Such an ownership structure would allow batteries to “stack” revenue from various sources, thereby improving their competitiveness.
“A battery can only belong to TSO [in the EU] if it is the only fully integrated network component,” says Lars Stephan, Head of Policy and Market Development at Fluence. “Then if it’s third-party ownership, you can accumulate more revenue. But on the other hand, I think they [TSOs] need to gain more experience on how they can trust a third party counterpart to deliver an essential service when needed, how to structure that. Stephan says the development of common communication interfaces between the parties will also need to be improved. “It’s still very early,” he said.
Although this decade only represents the dawn of batteries as transmission assets, Fluence sees considerable promise in the application. It currently follows a pipeline of “GW-scale” projects in EMEA in what it calls the “transmission segment”, with TSOs bidding on battery projects in support of transmission infrastructure, although the specific ownership structure of some potential projects is still unclear.
There are also a number of notable battery projects for the transmission segment in Europe. For example, in France, the 32 MW / 98 MWh RINGO project on the RTE network aims to strengthen transmission in congested parts of the network. And the German 1,300 MW “GridBooster” project, which was proposed in 2019, is currently seeing the first 450 MW of batteries approved on the TransnetBW and TenneT networks.
Further afield, countries with “long and lean” power grids and increasing penetration of renewables, such as Chile and Australia, are particularly well suited to batteries as transmission assets, with projects already In progress. Notably, in July, the Hornsdale power reserve of 150 MW / 193.5 MWh, supplied by Tesla and operated by Neoen, was approved by market regulators to provide 2,000 MW of equivalent inertia, or approximately 15% of the projected revenue shortfall in South Australia’s electricity state. network.
Long distance transmission
The use cases demonstrated in these projects illustrate how batteries can enable more efficient use of existing grid infrastructure in the event of increased renewable energy penetration, retirement of fossil fuel generators, or unique situations such as than those posed in the Baltic countries. However, it is in the support of long distance transmission lines that the concept of “virtual transmission” can have the most impact.
“The longer the virtual transmission line, the more likely the batteries are to be competitive,” says George Hilton, senior energy storage analyst at IHS Markit. “That’s because it would be more expensive to make upgrades to traditional infrastructure over that distance.”
Hilton cites the 3,800 kilometer Xlinks Morocco-UK power project, which would see an undersea HVDC interconnector between the countries as an example of batteries potentially boosting long-distance transmission. By adding batteries on either side of such a transmission link, “then you can transmit power over that distance without hitting the thermal limits of those cables, the voltage limits, and without affecting fault issues along those power lines,” says Hilton.
However, there are few real-world demonstrations of batteries performing such a role and Hilton envisions there to be challenges in operating them in this manner. “You have to manage the state of charge of those two batteries together and clearly you have limits to that because of the state of charge limits of the batteries on either side. Those are things that don’t have been tested in the real world. You can model it, but projects installed and operated that way have not been fully tested,” he says.
Given the exorbitant prices of such ambitious interconnect projects, the cost of batteries in such applications is less critical; however, the rising cost of batteries is likely to hold back some battery applications in the powertrain segment. With growing demand from the automotive sector and tight supply chains, prices have increased by around 30%. Litgrid’s Varanavicius dryly observes that the 200 MW second phase in Lithuania was purchased before the price increases occurred. He says the company’s 1MW innovation project will continue to prove itself after its initial demonstration phase.
“Like the public telescopes, which are made freely available to academics for their work, we have announced that companies, businesses and academics, not only in Lithuania but further afield, can use the 1 MW battery for future R&D studies,” says Varanavicius. The first cooperations of this nature were announced by Litgrid at the beginning of August. “This asset is not locked in, and it still offers growing battery skills in some companies.”
Litgrid Innovation Platform Gong
The 1MW/1MWh project in Vilnius won The smarter E award in the category of outstanding projects in 2022. The award jury noted that the installation of such battery projects would allow “greater energy independence and decarbonization for Lithuania and other regions”. Additionally, jurors noted that the project demonstrated “the pioneering idea of increasing grid capacity with batteries, which will gain even more popularity as the proportion of renewables increases.” Representatives from Litgrid and Fluence who, together with Siemens, executed the project, attended the award ceremony on May 10.
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