Spatiotemporal correlations in the power output of wind farms: On the impact of atmospheric stability

Nicolas Tobin, Adam Lavely, Sven Schmitz, Leonardo P. Chamorro

Research output: Contribution to journalArticle

Abstract

The dependence of temporal correlations in the power output of wind-turbine pairs on atmospheric stability is explored using theoretical arguments and wind-farm large-eddy simulations. For this purpose, a range of five distinct stability regimes, ranging from weakly stable to moderately convective, were investigated with the same aligned wind-farm layout used among simulations. The coherence spectrum between turbine pairs in each simulation was compared to theoretical predictions. We found with high statistical significance (p < 0.01) that higher levels of atmospheric instability lead to higher coherence between turbines, with wake motions reducing correlations up to 40%. This is attributed to higher dominance of atmospheric motions over wakes in strongly unstable flows. Good agreement resulted with the use of an empirical model for wake-added turbulence to predict the variation of turbine power coherence with ambient turbulence intensity (R2 = 0.82), though other empirical relations may be applicable. It was shown that improperly accounting for turbine-turbine correlations can substantially impact power variance estimates on the order of a factor of 4.

Original languageEnglish (US)
Article number1486
JournalEnergies
Volume12
Issue number8
DOIs
StatePublished - Apr 19 2019

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Keywords

  • Atmospheric stability
  • Coherence
  • Turbulence
  • Wind farm

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Energy (miscellaneous)
  • Control and Optimization
  • Electrical and Electronic Engineering

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