System Frequency
Summary
NESO publishes historic GB system frequency at 1-second resolution, with the statutory obligation to hold frequency at 50 Hz within a 0.5 Hz limit either side. The dataset records actual frequency deviations rather than changing any rule or charge. Files are large enough that NESO advises downloading the CSV and opening it in Notepad++.
Why it matters
This is the raw measurement of system inertia decline: as synchronous generation displaces, frequency excursions widen and the cost of holding 50 Hz migrates into ancillary service procurement. The data is useful to anyone modelling frequency response economics or curtailment risk, but it sets no price and creates no obligation.
Key facts
- •1-second resolution frequency data for Great Britain
- •Statutory target 50 Hz, statutory limit +/- 0.5 Hz
- •Time values in GMT from January 2020 onwards
- •Files large enough to require Notepad++ for full loading
Areas affected
Memo
This page holds the historic system frequency data for Great Britain at a 1 second resolution. It is the role of the National Grid ESO to keep the system frequency at 50 Hz, with a statutory limit of 0.5 Hz above or below this value. Time values are all given in Greenwich Mean Time (GMT) starting January 2020.<br/> >NOTE: Due to the size and format of these files, to view the data, please download the CSV file and open it with Notepad++ for complete document loading.