IN Brief:
- Harmony Link has entered engineering design after completion of its territorial planning stage.
- Litgrid has increased LitPol Link export capability and is scanning more than 5,000km of high-voltage lines using LiDAR.
- Lithuanian wind and solar capacity reached 6GW as transmission demand and storage connections continued to increase.
Lithuania’s transmission system operator Litgrid has moved the Harmony Link interconnector into engineering design while expanding cross-border transfer capability and introducing LiDAR monitoring across more than 5,000km of high-voltage lines.
The work forms part of a wider reinforcement programme as domestic renewable generation rises and the Baltic electricity system settles into synchronous operation with continental Europe. Harmony Link, the planned second onshore interconnector between Lithuania and Poland, completed its territorial planning stage after the Lithuanian government approved its engineering infrastructure development plan in June.
Litgrid has also started procurement for controllable shunt reactors required for the future interconnection infrastructure. The equipment will help manage reactive power and voltage conditions as the network’s operating pattern changes with additional cross-border transfer capability.
Long high-voltage circuits can produce excess reactive power when they are lightly loaded, pushing network voltage upwards. Shunt reactors absorb part of that reactive power, while controllable units give system operators greater scope to respond as loading changes. They therefore affect how effectively an interconnector can be operated rather than simply adding another item of substation equipment.
Changes are already being made to the existing Poland connection. In April, Litgrid implemented measures that increased the transmission capacity available for electricity exports through LitPol Link. The Lithuanian government has also designated reinforcement of the country’s interconnections with Latvia as a project of national importance.
Cross-border capacity is becoming more significant as local generation increases. Installed wind and solar capacity in Lithuania reached 6GW at the beginning of April, and renewable generators covered the country’s weekly electricity demand in full for the first time later that month.
Storage is developing alongside that generation. A fifth commercial battery energy storage system connected to Lithuania’s transmission grid in June, adding another controllable resource to a system in which production increasingly depends on weather conditions.
The pattern follows recent Lithuanian growth in renewable and storage connections, placing greater emphasis on transmission capacity, balancing resources, and visibility of the physical grid. Generation capacity can expand quickly at individual sites, but the network has to accommodate the combined flows created across the country.
Litgrid is improving asset visibility through an aerial survey of the entire national high-voltage transmission system. LiDAR three-dimensional laser scanning and aerial photography will be used across more than 5,000km of lines, creating detailed information about conductors, towers, vegetation, terrain, and surrounding infrastructure.
That information can support maintenance and modernisation planning by identifying clearance problems, vegetation encroachment, structural changes, and access constraints before they become operational faults. Digital surveying also provides a consistent network-wide dataset that can be compared over time rather than relying solely on individual field inspections.
The approach is a practical form of grid digitalisation. The underlying assets remain conductors, towers, substations, transformers, and protection equipment, but better spatial data can change how maintenance is prioritised and how reinforcement schemes are designed.
Demand on the transmission system is rising at the same time. Litgrid transmitted 4.631TWh to meet national demand during the first six months of 2026, 3.78% more than in the same period last year. The operator remained within its reliability thresholds, recording an Average Interruption Time of 0.581 minutes and Energy Not Supplied of 15.559MWh.
Interconnector availability was also high. NordBalt, the subsea connection between Lithuania and Sweden, recorded 99.6% availability during the half year. LitPol Link has operated in alternating-current mode since the Baltic synchronisation, with market capacity assessed against frequency-stability requirements.
Those operating figures sit behind the more visible construction programme. Renewable generators need an outlet for surplus production, neighbouring markets need dependable transfer capacity, and system operators need enough controllable resources to keep voltage and frequency within limits as flows change.
Batteries can absorb some short-duration imbalances, but they do not remove structural transmission constraints. A congested corridor can continue restricting renewable output even when storage is available elsewhere, while insufficient cross-border capacity can limit the value of surplus generation during periods of high wind or solar production.
Harmony Link therefore adds more than another trading route. Combined with LitPol Link, NordBalt, strengthened Latvia connections, storage, and network controls, it forms part of the infrastructure needed to operate the Baltic system with a larger indigenous renewable fleet and stronger integration into continental European electricity markets.
Litgrid is also planning across energy vectors. Together with gas transmission operator Amber Grid, it has prepared Lithuania’s first joint electricity, gas, and hydrogen network-development scenario to inform longer-term infrastructure decisions as electrification and potential hydrogen demand alter energy flows.
Investment in the transmission system reached €61m during the first half of 2026. The next engineering milestone for Harmony Link will be the progression from design and equipment procurement into construction, while the immediate network challenge is to keep existing infrastructure reliable as generation and cross-border flows increase around it.
