Baltic Storage Platform reached a noteworthy milestone at Kiisa in the course of the construction of the largest battery park in Continental Europe – for the first time in Estonia, a unique underground cable line operating at 330 kV voltage was installed, connecting the battery park with the connection point of the Estonian transmission network.
Two battery parks with a total capacity of 200 MW and a total storage capacity of 400 MWh will be constructed in Harju County through the joint venture Baltic Storage Platform, founded by the Estonian energy company Evecon, the French solar energy producer Corsica Sole and the French investment fund Mirova. Kiisa battery park is scheduled to be completed by the end of 2025 and Aruküla battery park in 2026. The battery parks will play a key role in the synchronisation of the Baltic countries with the European power grid.
“The construction of Kiisa battery park, with its cornerstone laid in the beginning of October, has advanced according to schedule. Construction on the substation building is steadily progressing, the foundations of the equipment have been laid and the foundations of the two 330 kV power transformers have been cast,” said Risto Virveste, Project Manager of Evecon. “However, the most significant detail is that recently, Connecto Eesti installed the first 330 kV alternating current underground cable line in Estonia. Cables with an operating voltage like that have never been installed before in Estonia. Usually, 330 kV overhead transmission lines are used for such solutions.”
The cable was manufactured in the Finnish Prysmian plant – a first for Estonia. It extends to 500 metres in length and has a notable diameter of 12.5 cm, said Risto Virveste. The cable was installed between the substation of the battery park and Elering’s 330 kV substation, which is where the connection point of the battery park with the Estonian transmission network is located.
“This cable is special due to its relatively high price. But in the current case, it was a reasonable solution, as there would have been crossings with several other 330 kV overhead transmission lines between Elering’s Kiisa substation and the battery park, which would in turn render the construction work difficult and expensive, as very high towers would need to be constructed, or the 330 kV overhead transmission lines of Elering would need to be reconstructed,” Virveste explained. The special nature of the cable and the voltage class are characterised by the fact that end insulators with a total length of 5 metres need to be installed at the ends of the cable.
“The installation work of the cable proceeded as planned and thanks to excellent preparation, we completed the installation of the cable in just three days. This is a great example of the level of professionalism and technical capacity of our team. Projects like these show how innovation and professional work combined help the Estonian energy system advance with great strides. The installation of the end joints in the spring will be the next stage,” said Valmar Raigo, Project Manager of Connecto Eesti.
