Wind Energ. Sci., 6, 131–147, 2021 https://doi.org/10.5194/wes-6-131-2021 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. Characterisation of intra-hourly wind power ramps at the wind farm scale and associated processes Mathieu Pichault1, Claire Vincent2, Grant Skidmore1, and Jason Monty1 1Department of Mechanical Engineering, The University of Melbourne, Melbourne, Victoria 3010, Australia 2School of Earth Sciences, The University of Melbourne, Melbourne, Victoria 3010, Australia Correspondence: Mathieu Pichault (
[email protected]) Received: 12 May 2020 – Discussion started: 5 June 2020 Revised: 15 September 2020 – Accepted: 8 December 2020 – Published: 19 January 2021 Abstract. One of the main factors contributing to wind power forecast inaccuracies is the occurrence of large changes in wind power output over a short amount of time, also called “ramp events”. In this paper, we assess the behaviour and causality of 1183 ramp events at a large wind farm site located in Victoria (southeast Australia). We address the relative importance of primary engineering and meteorological processes inducing ramps through an automatic ramp categorisation scheme. Ramp features such as ramp amplitude, shape, diurnal cycle and seasonality are further discussed, and several case studies are presented. It is shown that ramps at the study site are mostly associated with frontal activity (46 %) and that wind power fluctuations tend to plateau before and after the ramps. The research further demonstrates the wide range of temporal scales and behaviours inherent to intra-hourly wind power ramps at the wind farm scale. 1 Introduction hourly) ramp forecasts (Zhang et al., 2017; Cui et al., 2015; Gallego et al., 2015a).