Ofgem - Office of Gas and Electricity Market

03/03/2026 | Press release | Archived content

Frequency Risk and Control Report 2025: independent review

An independent expert review of the National Energy System Operator (NESO)'s 2025 Frequency Risk and Control Report (FRCR), evaluating the proposed reduction of minimum system inertia.

Main points

The FRCR outlines a sound general approach to risk management.

NESO's proposal to lower minimum inertia drew mixed industry feedback with unresolved concerns.

The FRCR depends on simulations, probability estimates, and cost appraisals, yet lacks detailed validation and uses a simplified frequency model that may overlook local issues impacting protection schemes and distributed generation.

While the evidence suggests reduced system inertia may not significantly increase risk, it is not sufficient to fully assure stakeholders.

The report recommends NESO to:

  • revise and republish the FRCR 2025 Report and related Methodology and Data documents to include simulation validation, clearer methods for estimating probabilities and system parameters, and explicit notes on conservative assumptions and their impacts
  • publish an update summarising the latest Low Frequency Demand Disconnection review findings, recommended changes, and their implementation status
  • provide evidence of Dynamic Containment's effectiveness and reliability across various system conditions
Ofgem - Office of Gas and Electricity Market published this content on March 03, 2026, and is solely responsible for the information contained herein. Distributed via Public Technologies (PUBT), unedited and unaltered, on July 01, 2026 at 07:19 UTC. If you believe the information included in the content is inaccurate or outdated and requires editing or removal, please contact us at [email protected]