Temporal structure of aggregate power fluctuations in large-eddy simulations of extended wind-farms

Stevens, R.J.A.M.; Meneveau, C.

doi:10.1063/1.4885114

Publication 28 · Wind-farm flow

Temporal structure of aggregate power fluctuations in large-eddy simulations of extended wind-farms

R.J.A.M. Stevens, C. Meneveau, J. Renew. Sustain. Energy 6, 043102 (2014).

Read the article Open-access version (arXiv manuscript)

Main finding

Spanwise turbine signals are nearly uncorrelated, while downstream signals are correlated with an advection-time delay. Streamwise and whole-farm aggregation suppresses intermediate frequencies more strongly than an independent 1/N expectation because delayed correlated signals partially cancel.

Power spectra for one turbine, a row, a column and a whole wind farm — **How to read the figure.** Power spectra for a single turbine, a spanwise row, a streamwise column and the whole farm (a), and the same rescaled by the number of turbines, so that independent signals would collapse onto one curve (b). The spanwise row collapses; the streamwise column and the whole farm fall below it at intermediate frequencies. Turbines in a column meet the same gust at an advection delay, and those delayed correlated signals partly cancel, so aggregation smooths more than independence would predict. Open the full-resolution figure. Figure 6. R.J.A.M. Stevens and C. Meneveau (2014). No separate licence is stated here; consult the original publication and credited source before reuse.

Why this matters

Supports layout-dependent temporal aggregation and a separation between mean power and fluctuation metrics.

Research context

Advective delay and downstream correlation explain much of the layout-dependent cancellation at intermediate frequencies. They do not explain the observed low-frequency minus-five-thirds power law.

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