Impact of hourly wind power variations on the system operation in the Nordic countries

Hannele Holttinen

Research output: Contribution to journalArticleScientificpeer-review

174 Citations (Scopus)


The variations of wind power production will increase the flexibility needed in the system when significant amounts of load are covered by wind power. When studying the incremental effects that varying wind power production imposes on the power system, it is important to study the system as a whole: only the net imbalances have to be balanced by the system. Large geographical spreading of wind power will reduce variability, increase predictability and decrease the occasions with near zero or peak output. The goal of this work was to estimate the increase in hourly load‐following reserve requirements based on real wind power production and synchronous hourly load data in the four Nordic countries. The result is an increasing effect on reserve requirements with increasing wind power penetration. At a 10% penetration level (wind power production of gross demand) this is estimated as 1·5%–4% of installed wind capacity, taking into account that load variations are more predictable than wind power variations.
Original languageEnglish
Pages (from-to)197 - 218
Number of pages22
JournalWind Energy
Issue number2
Publication statusPublished - 2005
MoE publication typeA1 Journal article-refereed


  • wind power impacts
  • power system impacts
  • wind power
  • reserve needs
  • wind power fluctuations


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