Neural Processing Letters
https://doi.org/10.1007/s11063-018-9922-5
Ordinal Multi-class Architecture for Predicting Wind Power
Ramp Events Based on Reservoir Computing
M. Dorado-Moreno
1
· P. A. Gutiérrez
1
· L. Cornejo-Bueno
2
· L. Prieto
3
·
S. Salcedo-Sanz
2
· C. Hervás-Martínez
1
© Springer Science+Business Media, LLC, part of Springer Nature 2018
Abstract
Wind power ramp events (WPREs) are strong increases or decreases of wind speed in a
short period of time. Predicting WPREs in wind farms is of vital importance given that they
can produce damages in the turbines, and, in any case, they suddenly affect the wind farm
production. In contrast to previous binary definitions of the prediction problem (ramp vs non-
ramp), a three-class prediction model is used in this paper, proposing a novel discretization
function, able to detect the nature of WPREs: negative ramp, non-ramp and positive ramp
events. Moreover, the natural order of these labels is exploited to obtain better results in the
prediction of these events. The independent variables used for prediction include, in this case,
past wind speed values and meteorological data obtained from physical models (reanalysis
data). Reanalysis will be also used for recovering missing data from the measuring stations in
the wind farm. The proposed prediction methodology is based on Reservoir Computing and
an over-sampling process for alleviating the high degree of unbalance in the dataset (non-ramp
events are much more frequent than ramps). Three elements are combined in the prediction
method: a recurrent neural network layer, a nonlinear kernel mapping and an ordinal logistic
regression,to exploit the information provided by the order of the classes). Preprocessing is
based on a variation of the standard synthetic minority over-sampling technique, which is
applied to the reservoir activations (since the direct application over the input variables would
damage its temporal structure). The performance of the method is analysed by comparing it
against other state-of-the-art classifiers, such as Support Vector Machines, nominal logistic
regression, an autoregressive ordinal neural network, or the use of leaky integrator neurons
instead of the standard sigmoidal units. From the results obtained, the benefits of the kernel
mapping and the ordinal model are clear, and, in general, the performance obtained with the
Reservoir Computing approach is shown to be very robust in the detection of ramps.
B M. Dorado-Moreno
manuel.dorado@uco.es
1
Department of Computer Science and Numerical Analysis, Universidad de Córdoba, Córdoba,
Spain
2
Department of Signal Processing and Communications, Universidad de Alcalá, Alcalá de Henares,
Spain
3
Department of Energy Resource, Iberdrola, Madrid, Spain
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