Work being done to synchronize the Baltic States' electricity grids with those of the rest of the European Union means that the number of electricity connections between Estonia and Latvia will be cut from three to two, through to year-end 2025.
Implicit in the synchronization with "continental" Europe is the need to de-couple from the Russian and Belarusian electricity networks, a project that was already underway before the start of the invasion of Ukraine in February but which has been given added impetus by it.
Elo Ellermaa, spokesperson for grid distributor Elering said: "Reconstructing power lines means that through to the end of 2025, one out of three direct connections will be permanently off-line, and capacity will be lower by that proportion. Other factors will affect the transmission capacity, also."
"These include the maintenance of other lines, or faults in Estonia, Latvia or even in the Russian Federation, because we are still connected to the Russian network. The ambient temperature also plays its part - for example, during summer heatwaves, transmission power must be cut down to avoid power cables overheating," Ellermaa continued.
The plan for Estonia, Latvia and Lithuania to de-couple from the Russian grid and synchronize to the European one are still both scheduled to take place at year-end 2025, and to that end Elering is to install three synchronous condensers within the next couple of years, to maintain inertia.
The first of these condensers is due to be ready in the first quarter of 2023.
Of the three cross-border electricity links between Estonia and its southern neighbor, line L301, which runs from Tartu to Valmiera, Latvia, has been off-line for a year already, ahead of the synchronization work.
At the same time, messages to the NordPool exchange relating to this have caused some confusion, ERR reports; a notification that maintenance work to L301 starting November 26 and due to end today, Thursday, is superfluous in that the line has been out-of-service for a year already.
A new urgent market message (UMM) will supersede the latest one noted above, through to the end of the synchronization work due to finish 2025, Ellermaa said.
In sort, daily UMM updates in relation to the L301 Estonia-Latvia electricity link does not equate to any actual new work taking place.
Elsewhere, temporary or unexpected work takes place in the normal run of things, such as interruptions today and Friday scheduled for another of the cross-border links, from Kilingi-Nõmme, Pärnu County, to Riga, which will deal with the more run-of-the mill issue of trees falling on power lines.
Transmission capacities between the two countries are calculated anew every day and reflected on the NordPool exchange. Elering and its Latvian counterpart conduct this work in accordance with set proportion.
While L301 work is set to finish ext spring, the third connection, L353 ((Viru-Tsirguliina), will undergo work, meaning that the two-out-of-three proportion of functioning cross-border links remains intact and the capacity stays around a third lower than in normal times.
The installation of condensers should aim to mitigate faults during the switchover period in 2025 or before that date, or even an intentional de-coupling from the Russian side.
EstLink-1 to be operational by the end of the week
Meanwhile in the opposite direction, the Estlink-1 undersea cable which links Estonia with Finland is still on-track to be up and running again on Sunday, after going off-line last Tuesday.
The 350MW cable was switched off following a technical fault at the Harku sub-station in Estonia.
A NordPool UMM states that Estlink-1 will be on-line again from midnight on Sunday, December 4, Ellermaa said.
Estlink-1 and Estlink-2 are co-owned by Elering and its Finnish equivalent, Fingrid, while plans are in place for an Estlink-3 connection also.
While the reduced capacity the current Estlink-1 outage resulted in led to fears of diverging electricity prices between the two countries, with Estonia's being the higher price, in reality this has not materialized as of the time of writing
For instance today, Thursday, the NordPool daily average stands at €393 per MWh both in Finland and Estonia. A week ago, while the price was considerably lower at €262 per MWh, this level held true for both countries.
Editor: Andrew Whyte, Marko Tooming