ČEPS completes reconstruction of Kočín substation in Czechia

At the end of November this year, one of the largest projects in the Czech Republic’s transmission system, “Kočín substation – expansion and reconstruction, connection of power lines,” was completed and received final approval. Construction took place between 2017 and 2023 and included the complete reconstruction of the switchyards and parts of the connected power lines. The total cost of this investment project is almost CZK 4 billion, 30% of which is expected to be covered by EU grants.

The Kočín transformer station (TR) comprises 420 kV and 123 kV switchyards. Two unit lines from the Temelín power plant feed into the 420 kV switchyard, transmitting their output to other stations in the transmission system: the nearest one, Dasný, which is connected to the Slavětice transformer station, as well as Přeštice, Řeporyje and Chodov.

“This investment project will enable the development of the transmission system in line with further plans for the Temelín power plant. It has increased the reliability of evacuating the output of the existing nuclear units, and, by modifying the transmission system’s supply of the plant’s own consumption, it has enhanced nuclear safety,” says Karel Slončík, a member of ČEPS’s Board of Directors responsible for the Management, Operation and Maintenance of the Transmission System division.

The 420 kV switchyard was expanded from 18 bays to 24, and its short-circuit withstand capacity was increased to 63 kA, the highest value in the transmission system. The switchyard is ready for new unit lines from the Temelín power plant, a new double-circuit line to the Mírovka substation near Havlíčkův Brod, the duplication of the existing line to Přeštice, and a line to Slavětice.

The number of bays in the 123 kV switchyard increased from 17 to 21. The expansion will make it possible to connect two 110 kV lines in the future to provide backup power for the Temelín power plant’s own consumption, duplicate distribution lines and provide capacity for future development. The transformer capacity at the Kočín station supplying the 123 kV switchyard was also increased to 2x350 MVA.

Other significant structures built as part of the project include a cable connection between the 420 kV and 123 kV switchyards to enhance nuclear safety, noise barriers around the transformers, oily-water treatment plants, physical security systems and new LED lighting, which significantly reduces light pollution.