Nonlinear dynamics of back-to-back converters in small wind turbine systems: novel chaotic phenomena occurring during disturbances

This manuscript studies the behavior of a small wind turbine system constituted by a permanent magnet synchronous generator connected to the grid via a back-to-back converter. In particular, the nonlinear dynamics of a grid-side converter is analyzed in the presence of voltage sags. The study shows that new chaotic phenomena are generated when the size of the dc-link capacitor is reduced. The reported time waveforms and state-space attractors highlight that the system becomes chaotic during the voltage sag, being stable before and after the disturbance. Finally, the chaotic behavior is validated via the computation of the maximum Lyapunov exponent, confirming the novel phenomenon described herein.