Analysis of mechanical power fluctuations in asynchronous WECs

In recent years, wind energy has become an important part of electrical power generation in some countries. Some problems such as small voltage variations and flicker can be caused by wind turbines and wind farms, when wind speed variations produce mechanical power fluctuations. The consequence is that speed changes in the turbine rotor are produced, which lead to variations in their currents and voltages. The purpose of this paper is to study the relationship between fluctuations of mechanical power, rotor speed and currents as a function of their frequencies, in order to establish the models that should be used to analyse slow voltage variations and flicker problems. Simulations are carried out using a dynamic model of the induction machine and assuming sinusoidal waveforms for the fluctuations of the mechanical power.