Nonlinear approximation of wind turbine capacity factor under Rayleigh winds

Yuri Ditkovich, Gilad Zangwill, Alon Kuperman

Research output: Contribution to journalArticlepeer-review


Wind inconsistency prevents the wind turbine from operating at its rated power most of the time. The concept of capacity factor (CF) is usually employed to evaluate the expected (usually annual) energy yield of wind turbine. The linear approximation is no longer valid for the winds outside the mentioned range. In this note, a nonlinear approximation of CF is proposed, valid in the whole feasible speed range. The proposed function depends on the turbine rated power and rotor blade diameter only as well and is verified by comparing the approximated CF to the CF, calculated using spreadsheet approach. A method of simple CF prediction of wind turbines, operating under Rayleigh winds, was discussed in the paper. The approach is based on a nonlinear approximation of the CF versus average wind speed curve, which only necessitates information regarding turbine rated power and rotor diameter. The presented derivation was inspired by a previously proposed linear approximation, valid only in moderate wind speeds range.

Original languageEnglish
Pages (from-to)1818-1821
Number of pages4
JournalInternational Transactions on Electrical Energy Systems
Issue number12
StatePublished - 1 Dec 2014
Externally publishedYes

ASJC Scopus subject areas

  • Modeling and Simulation
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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