Effect of static/dynamic air‐gap eccentricity on stator and rotor vibration characteristics in doubly‐fed induction generator.

This article has conducted a comprehensive study on the stator and rotor vibration characteristics of the doubly‐fed induction generator (DFIG) in the case of radial air gap eccentricity (RAGE). Differently from other previous studies, this paper not only investigates the vibration characteristics of stator and rotor in radial static air gap eccentricity (RSAGE) and radial dynamic air‐gap eccentricity (RDAGE) fault but also takes the radial hybrid air gap eccentricity (RHAGE) into account. Through theoretical derivation, the detailed expressions of stator magnetic pull per unit area (MPPUA) and rotor unbalanced magnetic pull (UMP) are obtained. The finite element analysis (FEA) and experiment based on a two pairs of poles DFIG, and the results are consistent with theoretical calculations. It is shown that RAGE will enlarge the magnitude of stator MPPUA/vibration and rotor UMP/vibration. Specifically, RSAGE will not change the frequency components of stator MPPUA/vibration but will bring new frequency components to rotor UMP/vibration. However, both stator MPPUA/vibration and rotor UMP/vibration will generate new frequency components during RDAGE fault. In addition, the effect of RHAGE is the superposition of RSAGE and RDAGE. The research conclusions obtained in this paper can be used as a supplementary criterion for diagnosing the eccentricity of DFIG. [ABSTRACT FROM AUTHOR]