Scottish and Southern Electricity Networks (SSEN), operating as Scottish Hydro Electric Transmission under licence, is to proceed with plans to reinforce the existing North East and East Coast onshore transmission system following a positive 'proceed' signal in this year's Network Options Assessment (NOA) report published by the System Operator.
The NOA report takes information from each of the three Transmission Owners (TOs) about their transmission network reinforcement options. It combines this with future generation and demand scenarios and carries out a GB wide cost benefit study to allow the System Operator, National Grid, to make independent recommendations about what it considers the optimal sequence and timing of transmission investments.
In this year's NOA report, National Grid has recommended that work should proceed to incrementally reinforce and increase the capacity of the existing North East and East Coast transmission system. The reinforcements are planned to take place in three stages; this will initially see one of the overhead lines running south from Kintore upgraded to enhance its capacity at the existing operating voltage of 275kV by 2023. This line will then be upgraded along with the existing 275kV lines running between Blackhillock substation near Keith and Kintore to operate at 400kV in 2026. The final stage will see the proposed subsea High Voltage Direct Current (HVDC) link from Peterhead to Hawthorn Pit in the north east of England by 2028.
The reinforcements are deemed optimal in all four future energy scenarios modelled by National Grid, sending a very strong 'proceed' signal. The subsea HVDC link from Peterhead to Hawthorn Pit has received a positive 'proceed' signal in the NOA report for the third year running. Once complete, the reinforcements will provide additional network capacity, strengthening the power transfer capability of the transmission system and helping to alleviate existing and future grid constraints.
Commenting, David Gardner, Director of Transmission, said:
"This is welcome news for our customers and energy consumers across the north of Scotland, helping alleviate grid constraints across our network as well as enhancing wider system security."
"Work is now underway to progress plans for the proposed reinforcements. As a responsible developer, we are committed to working closely with the local community and other interested parties as we take forward these reinforcements."
The existing 275kV East Coast transmission line runs from Kintore in the north east of Scotland in SSEN's transmission region to Kincardine in SP Transmission's region. The existing 275kV transmission lines between Blackhillock and Peterhead via Rothienorman and between Rothienorman and Kintore are also due to be upgraded as part of the recommended reinforcements. While these lines currently operate at 275kV, the towers are already capable of 400kV operation. New substations will be required at Alyth, Kintore and Rothienorman.
The full NOA 2017/18 report can be viewed on National Grid's website.