Improving windfarm operation practice through numerical modelling and Supervisory Control and Data Acquisition data analysis

Usually, wind energy assessment on a new windfarm is conducted with maximum effort prior to the installation of the turbines by using both numerical and experimental investigations. Yet, often the windfarm performances during operation are not as good as expected. This issue can be investigated with a deep analysis of the operational conditions of the windfarm. The large amount of data collected by the SCADA (Supervisory Control and Data Acquisition) systems installed on the turbines can be very helpful. In the present study, the performances of a windfarm were analysed through the elaboration of the SCADA data from a windfarm in southern Italy; in this site, Sorgenia Green installed nine aerogenerators with a rated power of 2 MW each, on a hilly area with gentle slopes. A systematic approach is proposed to isolate the downtime because of malfunctioning and a manifold investigation is applied to the operational phase: several methods (polar efficiency plot, multidimensional graphical analysis, sectorial power curve and misalignment index, respectively) are suggested and applied for unveiling the sectors where the production output is most affected by the wake interactions. Numerical windflow modelling is performed in the wind rose sectors where underproduction is highlighted by a SCADA data analysis: finally, a SCADA database is employed for testing the goodness of the simulations.