Case study: Flicker emission and 3P power oscillations on fixed-speed wind turbines

This paper studies the influence that the power oscillations due to the tower shadow effect and the wind shear have on the flicker emission of fixed-speed wind turbines. For three-bladed wind turbines, the frequency of this characteristic fluctuation of power is 3 times the blade rotational frequency, and it is known as 3P oscillation. This work aims to analyse real measurement data from an experimental wind farm in Northern Spain in order to extract time-frequency features related to the 3P oscillation. In the same way, the algorithm that measures the generated flicker during continuous operation of wind turbines is applied to the recorded data. Using the instantaneous flicker sensation and the short-time flicker severity, the correlation between the 3P oscillation and the flicker characteristic of a wind turbine is presented. The results demonstrate that monitoring 3P power oscillation allows obtaining an estimation of the flicker emission on wind turbines.