Synchronous generator eccentricities modeling by improved MWFA and fault signature evaluation in no-load E.M.F.s and current spectra

In this paper an accurate modeling of air-gap length function in polar and interpolar regions of non- isotropic synchronous generators is presented, for use in the MWFA (modified winding function approach), to obtain accurate machine simulations with eccentricities. Air-gap in interpolar regions is usually poorly modeled in current literature. Inductances obtained by the improved MWFA have been compared with 3D-FEM model obtained ones. External no-load e.m.f. and current spectra have been evaluated for a medium-power alternator with non-aligned rotor, and with various static and dynamic eccentricity degrees. Fault signatures appear all over the spectra, with variable entities, whose comprehensive evaluation can be used for fault severity assessment.