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Trends of frequency deviations

| 2025:1091 | Viktorija Dudjak, Jonas Persson, Markus Björklund
In this report grid frequency statistics of the last two decades have been examined together with analysis of inertia values of the Nordic Power System. Interviews have been held with the Nordic Nuclear Production Plant owners and the Swedish and Finnish TSOs. Conclusions are made whether it exist correlations with system quantities like frequency quality, inertia, wind power production, wear and tear of nuclear plants, and system services.
2025 1091 Rapportbild Webben
  • Nordic Nuclear Production Plant owners do not believe that there is a wear and tear of their plants related to the quality of the grid frequency.
  • The quality of the grid frequency has been improved during the last four years which is a result of larger volumes of system services such as Automatic Frequency Restoration Reserve, a-FRR.
  • During months of high wind power production the grid frequency shows better quality compared to months with less wind power production.
  • The system service Fast Frequency Reserve, FFR is an effective tool to counteract the lack of inertia.
  • It can be beneficial to develop frequency products like FFR also for over-frequencies in periods of low inertia.
  • Statistically it is shown in the report that the frequency is more often outside the interval +/-0.1 Hz around the hour shift, i.e., around the full hour. This is a conse­quence of how energy is traded.
  • During twenty-one years, the frequency has been higher than 50.1 Hz at 7:00 in the morning (Finnish Time) at 300 days. This shows that the frequency quality is worse during large load changes in the morning around the full hours.