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  • Report
  • Nuclear Power

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

Results from the report are:

  • 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.

Publications and reports

Here you will find reports and fact sheets from the program.

    • Report

    Fast Frequency Support Impact On Nuclear Generation

    This project assessed how Fast Frequency Support (FFS) from an HVDC link interacts with nuclear-type synchronous generator dynamics.

    |2025:1145Danilo Obradovic', RISE
    2025-1145
    • Report

    Impact of over-frequency events on Nordic NPPs

    This report quantifies over-frequency events by using a simulation model of the Nordic synchronous system and simulating different faults related to the HVDC links, in combination with operating conditions of high and low inertia.

    |2025:1118Matilda Arvidsson, Andreas Benjaminsson Lucas Finati Thomée, Daniel Karlsson
    Bild till webben 2025-1118
    • Report

    Exchange Strategies for Power Electronics in Rectifiers and UPS System for NPP

    Replacing outdated power electronics in NPP auxiliary systems is crucial for maintaining operational reliability and safety.

    |2025:1107Frede Blaabjerg
    bild webben.png
    • Report

    Trends of frequency deviations

    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.

    |2025:1091VIKTORIJA DUDJAK, JONAS PERSSON, MARKUS BJÖRKLUND
    2025 1091 Rapportbild Webben