Comment on wes-2022-14

Abstract

Hourly modeled wind turbine power output time series – modeled from outputs from the mesoscale numerical weather prediction system WRF – are used to examine the spatial smoothing of various wind farm portfolios located on a complex isolated island group with a surface area of 1400 km2. Power spectral densities (PSD), hourly step change functions, and duration curves are generated, and the 5th and 95th percentiles of the step change functions are calculated. The spatial smoothing is identified from smaller high frequency PSD values, less hourly fluctuations, and more flat duration curves per installed wind power capacity, compared to single wind turbine outputs. A discussion on the limitation of the spatial smoothing for the region is included, where a smoothing effect is clear for periods up to 1–2 days, although most evident at the higher frequencies. By maximizing the smoothing effect, optimal wind farm portfolios are presented with the intention to minimize the overall wind power fluctuations. The focus is mainly on the smoothing effect in highest resolvable frequencies. Optimizing wind farm capacities at fourteen pre-defined good wind farm site locations has a minimal improvement on the hourly fluctuations. However, choosing good combinations of the individual wind farm site locations decrease the 1–3 hourly fluctuations considerably; the optimized wind farm portfolios consist of distant wind farms, while poor portfolios consist of clustered wind farms. The 5th and 95th percentiles are 15 % less for an optimized portfolio with four wind farms compared to a poor combination of four wind farms.