Sweden's power transmission system operator Svenska Kraftnat said in a message to the Nord Pool power exchange last night that NordBalt was back in operation. It did not say what had caused the failure, however.
Lithuania's power transmission system operator Litgrid confirmed on Tuesday that the cable was back in service. It said earlier that the interconnection had gone offline because of a failure on the Swedish side.
The 700-megawatt interconnection went offline in the morning of June 7, prompting Lithuania, Latvia and Estonia to activate their emergency power reserves.
The Estlink 1 between Estonia and Finland as well as combined heat and power plants in Estonia and Latvia were down for maintenance last week, too.
These factors sent wholesale electricity prices in all three Baltic countries soaring by 52% last week, compared with a week earlier, to 45.23 euros per megawatt-hour (MWh).
The 450-kilometer-long NordBalt experienced frequent outages following its launch in February 2016. The interconnection underwent warranty repairs, which involved replacing underground cable joints in Lithuania and Sweden, in 2018 and scheduled maintenance last autumn.
According to Litgrid, NordBalt's availability reached a very high 99.95% last year.
The strategic project worth 550 mln euros was carried out by Litgrid and Svenska Kraft.