IN Brief:
- More frequent day-ahead restrictions will apply to North Sea Link, Viking Link, NEMO Link, and ElecLink.
- Limits will be based on two-day-ahead and day-ahead forecasts where intraday action may be insufficient.
- Capacity can be restored intraday when network conditions and system forecasts improve.
National Energy System Operator is increasing its use of day-ahead transfer restrictions on four electricity interconnectors linking Great Britain with continental and Nordic power markets.
Beginning with the operational day starting at 23:00 on 23 July 2026, the revised approach applies to North Sea Link, Viking Link, NEMO Link, and ElecLink. Restrictions may be introduced where forecast interconnector schedules create system-security problems that cannot be resolved reliably through later intraday action.
North Sea Link connects Great Britain with Norway, Viking Link with Denmark, NEMO Link with Belgium, and ElecLink with France. Collectively, the four assets provide several gigawatts of controllable cross-border capacity between markets with different generation mixes, weather patterns, demand profiles, and wholesale prices.
Using two-day-ahead and day-ahead forecasts, NESO will assess expected generation, demand, network outages, transmission constraints, and interconnector nominations before deciding whether transfer capability must be reduced. Where updated conditions improve, some or all of the restricted capacity can be released during the intraday period.
That process allows operational limits to be revised as weather, demand, plant availability, and market positions become clearer. Available restriction capacity will be allocated equitably according to the capability declared by the affected interconnectors at the two-day-ahead stage.
Similar intraday limit mechanisms are intended for IFA, IFA2, and BritNed at a later stage, extending the framework across a larger proportion of Britain’s cross-border electricity links.
Commercial schedules remain bounded by network conditions
Interconnector flows usually follow price differences between connected markets, with electricity moving toward the more expensive region. That commercial direction does not always correspond with the transmission capacity available behind the converter stations on either side of the link.
An import can increase loading on circuits carrying electricity away from a landing point, while an export can require additional domestic generation to move toward the connection. Depending on demand, outages, generation location, and network topology, the same nominal transfer may relieve one constraint and worsen another.
Day-ahead markets establish the principal commercial position, but physical conditions continue to change before real-time operation. Wind forecasts move, generators become unavailable, demand differs from expectation, and circuits can trip or return from maintenance, requiring schedules to be reassessed as the operating hour approaches.
Intraday trading and balancing actions absorb part of that uncertainty, although sufficient time or volume may not remain to resolve every network issue. Introducing restrictions earlier gives market participants clearer limits before final schedules form, while potentially withholding capacity that later proves usable.
The ability to release capacity intraday is intended to reduce unnecessary curtailment of cross-border trade. Its effectiveness will depend on dependable data exchange, recalculation of secure limits, and consistent capability declarations between NESO, interconnector operators, and market participants.
Britain’s growing interconnector fleet is operating alongside increasing offshore wind output and persistent internal transmission constraints. Large volumes of generation are concentrated in northern and coastal regions, while demand remains centred further south, creating periods when imported or exported flows interact with already congested domestic routes.
New infrastructure will reduce some of those constraints over time, with the proposed Western Link 2 HVDC route between Scotland and Wales intended to add another 2GW of controlled north–south transfer capability. Its delivery, however, remains several years behind the immediate operational requirement.
Interconnectors continue to provide valuable flexibility during low renewable output, plant outages, and periods of surplus generation. Their contribution depends on simultaneous conditions in both connected markets and on the ability of domestic networks to carry power between converter terminals, generation, and demand.
A restriction does not necessarily indicate a fault or reduced technical availability within the interconnector itself. The cable and converter stations may remain fully capable while the wider transmission network cannot accommodate the commercial schedule without excessive redispatch or unacceptable exposure following a credible fault.
Economic effects will depend on the frequency, scale, direction, and duration of the restrictions, as well as the amount of capacity subsequently restored intraday. Persistent limits could affect congestion income, price convergence, balancing costs, and trading strategies, whereas occasional targeted action may avoid more expensive real-time intervention.
Relevant restriction information will be published through NESO’s data services, allowing the operating record to show how day-ahead limits interact with forecast accuracy and intraday release. That record will also indicate whether earlier intervention produces more predictable constraint management without unnecessarily reducing cross-border capacity.
Every imported or exported megawatt must pass through a physical network with finite thermal, voltage, stability, and contingency limits. The revised process places those limits earlier within the commercial timetable while preserving the ability to restore capacity when updated system conditions permit.
