National Grid has announced a significant expansion of Dynamic Line Rating (DLR) technology across its electricity transmission network in England and Wales. Under a new five-year contract, Dynamic Line Ratings will be deployed across an additional 585km of key north-to-south transmission routes, potentially saving consumers up to £50 million.
Meeting the growing demand for electricity requires both new infrastructure and smarter use of what already exists. DLR is an innovative yet proven technology that continuously monitors overhead line conditions to calculate a real-time capacity rating based on actual conductor behaviour and local weather, rather than the fixed conservative assumptions that have historically governed line ratings.
The result is a safe, reliable optimisation of available capacity on existing infrastructure, with the sensors and data analytics platforms allowing for a safe increase of the power carrying capacity of a circuit by an average of 8%. This reduces the need for constraint payments, where a generator is paid to stop generating to avoid overloading the electricity network.
Installations will take place across three network boundaries (in the North East on 345km of overhead line, in the Humber area and East Anglia covering an additional 240km) with further planned over the 5 year period. This additional rollout means that 39 circuits, covering over 900km of National Grid’s transmission network, primarily key north to south power flow routes, will now have the technology installed.
DLR is one of a number of innovative technologies National Grid is deploying to manage and upgrade its network. Initiatives include deploying advanced power flow controllers, which intelligently and instantly route power through circuits which have available capacity, artificial intelligence which allows data centres to adjust their energy use in real time and drones to capture images and data to inform maintenance and investment programmes. Across the RIIO-T2 regulatory period (2021 to 2026), NGET’s DLR installations have saved £21 million in constraint costs and formed part of the deployment of grid enhancing technologies and upgrade of existing lines which has added over 16GW of new transfer capacity to the network.
Alice Delahunty, President of National Grid Electricity Transmission said, “By embracing innovation and using cutting-edge technology such as Dynamic Line Rating we are unlocking greater capacity on our existing network and enabling more renewable energy to flow to homes and businesses.
“Integrating grid-enhancing technologies such as these will deliver significant savings for consumers by reducing constraint costs and is an important part of our work to upgrade the grid to deliver a resilient, future-ready energy system.”
This work is being completed in partnership with three companies, LineVision, Ampacimon, and Heimdall, through a five-year contract. This establishes a trusted base of suppliers to develop and deploy DLR systems, accelerating the speed and scale of the rollout of the technology. The majority of installations are expected to be complete by 2028 and will be delivered through a variety of different solutions, including using drones to mount sensors to live power lines, avoiding the need to wait for planned outages of key transmission routes.
What is Dynamic Line Rating?
Electricity transmission power lines have historically been operated using a ‘static’ line rating calculated using conservative and static values for assumed weather conditions. Attaching sensors to continually monitor lines provides continuous data in order to calculate a ‘dynamic line rating’ (DLR). This rating can then be used by network operators to maximise the amount of power that can safely be transmitted through that transmission line. The dynamic line rating is determined by a power line’s physical and electrical properties; this includes size, resistance and maximum safe operating temperature, as well as the.
From pilot to rollout: National Grid’s use of DLR
This expansion of DLR across National Grid’s network follows 8 years of testing and expansion with US-based DLR provider, LineVision. Following the successful implementation of DLR technology on National Grid’s networks in New York and Massachusetts, National Grid ran a two-year trial on a 275kV transmission circuit between Penwortham and Kirkby in Cumbria between 2022 and 2024.
In 2025 the technology was expanded to cover nine further circuits, five between Penwortham (Preston) and Daines (Manchester) and four circuits from Norton (Middlesborough) to Thornton (York) – together increasing the capacity of over 275 kilometres of OHL conductor.
