GSR034 Security and Quality of Supply Standard (SQSS) proposed changes
- Publication type:
- Code modification
- Publication date:
- Topic:
- National Energy System Operator (NESO), Energy codes
- Subtopic:
- Security and quality of supply standard (SQSS)
Outcome of proposed changes to Security and Quality of Supply Standard (SQSS), GSR034 'Review of Loss of Power Infeed Risk for Offshore DC Converters'.
Details of outcome
We have approved the proposed changes to the National Electricity Transmission System Security and Quality of Supply Standards (SQSS), GSR034. We consider that the enduring benefits of this modification proposal outweigh the short-term increase in frequency response costs and therefore consider it to better facilitate the Applicable SQSS Objective.
Start date
13 March 2026.
Code modification description
GSR034 was raised by NESO on 22 October 2025. The proposal seeks to review whether the existing SQSS limit on the maximum loss of power infeed from a single offshore DC converter, currently set at the normal infeed loss limit of 1320MW, remains appropriate under modern offshore transmission design. The Proposer identified that this limit restricts the use of larger HVDC converter capacities, which in turn forces offshore wind farms to split their connections across multiple circuits, increasing infrastructure requirements and costs.
The Proposal seeks to replace the normal infeed loss limit with the infrequent infeed loss risk for offshore DC converters by modifying SQSS clauses 7.7.2 and 7.12.2. Under this revised approach, single converter capacities above 1320MW (e.g., up to 1800 MW) could be accommodated, enabling more efficient offshore connection designs.