Impact of Actual Wind Speed Distribution on the Fault Characteristic of DFIG Rotor Winding Asymmetry

Abstract

Studies show that in industrial wind turbines (WTs), the wind speed may significantly vary across the rotor disk area. This variation may originate from different parameters, including wind shear (WS) and tower shadow (TS), which affect the mechanical load and the generated electrical power. However, the influence of wind speed variation on the fault characteristics of WTs has rarely been investigated so far. As an improvement, this study made an attempt to investigate the impact of spatiotemporal distribution (STD) of wind speed on the fault characteristic of the doubly fed induction generator (DFIG). The primary contribution of this article lies in two aspects: 1) establishment of a new equivalent wind speed (EWS) model comprehensively considering the affecting parameters, including WS, TS, and turbulence, and 2) reanalysis of the rotor winding asymmetry (RWA) fault characteristics under EWS, and thus new characteristics of fault were obtained. Simulations and experiments were also carried out to evaluate the accuracy of the theoretical analysis. The obtained results reveal that in addition to the original characteristic frequency, which is correlated with RWA fault, other modulation frequencies are also correlated with wind speed distribution. It is concluded that the RWA fault characteristics of DFIG are different from those of the ordinary induction generator considering the STD of the wind speed. Importantly, the obtained results are expected to improve the fault diagnosis of DFIG.