GSR038: Single Transformer Offshore AC Substations
What is being proposed
This modification is proposed to assess the restriction in Clause 7.7.1.1 that effectively requires two offshore ACAlternating Current (AC) transformers for grid entry point capacities of 90 MW or more.
Current status
03/03/2026 - Proposal raised on 24 February 2026 and will be presented at the SQSS Panel on 24 March 2026.
Details
Timeline
Analysis
NESO has raised a modification to assess whether offshore wind farms of 90MW or more should be required to have two AC transformers at their grid connection point. The current SQSS rule 7.7.1.1 effectively mandates dual transformers for these capacities. The proposal will go to SQSS Panel on 24 March 2026.
Why it matters
This targets a specific redundancy requirement that may be forcing offshore projects to over-engineer their electrical infrastructure. As such, relaxing the dual transformer rule would reduce capital costs for offshore wind but potentially increase reliability risks during transformer maintenance or failure.
Key facts
- •90MW capacity threshold for dual transformer requirement
- •Clause 7.7.1.1 of SQSS
- •SQSS Panel meeting 24 March 2026
- •High impact on offshore transmission owners and generators