As the Russian and Finnish power systems are asynchronous, a direct AC connection was not possible and a HVDC-back-to-back station was needed.
[3] A fourth unit was added in 2001[2] and the control and protection equipment of the three original poles has subsequently been modernised.
[4] In contrast to most other HVDC plants, its converters did not originally allow bidirectional energy to transfer, but only from Russia to the power grid of Finland.
On 13 May 2022, RAO Nordic released a statement saying they were halting the import of power into Finland due to lack of payment.
[6] The substation consist of four independent, parallel symmetrical monopole (centre-grounded) back-to-back units, each rated 355 MVA and operating with a voltage of ± 85 kV.